UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

Filed by the Registrant  ☒                            Filed by a Party other than the Registrant  ☐

Check the appropriate box:

USG CORPORATION

(Name of Registrant as Specified in Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

USG Corporation

550 West Adams Street

Chicago, Illinois 60661

Founded in 1902

August 23, 2018

Dear Fellow Stockholder:

It is a pleasure to invite you to attend a special meeting of the stockholders of USG Corporation (“USG,” “we,” “our” or the “Company”). The special meeting will be held at 9:00 a.m., Chicago time, on September 26, 2018, at USG Corporate Headquarters, 550 West Adams Street, Chicago, Illinois 60661-3676. The attached notice of special meeting of stockholders and proxy statement discuss the items scheduled for a vote by stockholders at the meeting.

On June 10, 2018, we entered into an Agreement and Plan of Merger (as it may be amended from time to time, the “merger agreement”) with Gebr. Knauf KG, a limited partnership (Kommanditgesellschaft) organized under the laws of Germany (“Knauf”), and World Cup Acquisition Corporation, a Delaware corporation and an indirect, wholly-owned subsidiary of Knauf (“Merger Sub”), pursuant to which, subject to the satisfaction of customary closing conditions, Merger Sub will be merged with and into the Company (the “merger”), with the Company continuing as the surviving corporation in the merger and an indirect, wholly-owned subsidiary of Knauf.

At the special meeting, our stockholders will be asked to consider and vote on a proposal to adopt the merger agreement. In addition, our stockholders will be asked to consider and vote on a proposal to approve, on a non-binding, advisory basis, the compensation payments that will or may be paid or become payable to the Company’s named executive officers and that are based on or otherwise relate to the merger and the agreements and understandings pursuant to which such compensation will or may be paid or become payable (the “transaction-related named executive officer compensation”). Finally, our stockholders will be asked to consider and vote on a proposal to approve the adjournment of the special meeting, if necessary or appropriate, including to solicit additional proxies if there are insufficient votes at the time of the special meeting to approve the proposal to adopt the merger agreement or in the absence of a quorum (the “adjournment proposal”).

If the merger agreement is adopted and the merger is completed, at the effective time of the merger, each share of our common stock, par value $0.10 per share (“common stock”) issued and outstanding immediately prior to the effective time of the merger (other than shares of our common stock owned by Knauf and its subsidiaries, the Company and its subsidiaries or excluded holders, as defined in the accompanying proxy statement) automatically will be converted into the right to receive the closing consideration of $43.50 in cash, without interest and subject to tax withholding as applicable (the “closing consideration”). In addition to the closing consideration, as contemplated in the merger agreement, the Company declared a conditional special cash dividend of $0.50 per share of our common stock (the “conditional special dividend”) payable to holders of our common stock as of the record date of the special meeting (subject to due bill trading as further described in the accompanying proxy statement). The conditional special dividend is conditioned on the merger agreement being adopted by our stockholders at the special meeting and, if the merger agreement is so adopted, will be paid following certification of the results of the special meeting. The payment of the conditional special dividend is not conditioned on completion of the merger. For discussion of the impact of the merger, including the closing

consideration and the conditional special dividend, on each outstanding Company stock option, time-vesting restricted stock unit, market share unit, performance share and deferred stock unit, see the section entitled “The Merger Agreement—Treatment of Company Equity Awards” in the accompanying proxy statement. The total consideration, consisting of the closing consideration and the conditional special dividend, of $44.00 per share of our common stock represents a premium of approximately 31% to our unaffected closing price of $33.51 and a 36% premium to the $32.36 average closing price for the preceding 12-month period, both as of March 23, 2018, the business day immediately prior to the public announcement of Knauf’s proposal to acquire the Company.

Concurrently with the execution of the merger agreement, Berkshire Hathaway Inc., on behalf of itself and certain of its direct and indirect subsidiaries that own shares of our common stock (collectively, “Berkshire”), entered into a voting agreement, dated June 10, 2018, with Knauf and Merger Sub, in which Berkshire agreed, among other things and subject to the terms thereof, to vote (or cause to be voted) all shares of our common stock then beneficially owned by Berkshire, directly or indirectly, “FOR” adoption of the merger agreement, approval of the merger and the consummation of all of the transactions contemplated thereby and against any competing acquisition proposals relating to the Company. As provided in its Schedule 13D filed on June 11, 2018, Berkshire owns 43,387,980 shares of our common stock, which represents approximately 31.1% of the shares of our common stock issued and outstanding based on 139,462,508 shares of our common stock outstanding as of June 7, 2018 as represented in the merger agreement. Pursuant to the merger agreement, Knauf has agreed to vote, or cause any of its applicable subsidiaries to vote, in person or by proxy, all shares of our common stock held by Knauf, directly or indirectly, as of the record date of the special meeting “FOR” adoption of the merger agreement, “FOR” approval, on a non-binding, advisory basis, of the transaction-related named executive officer compensation, and, as requested by the Company, any other action in furtherance thereof to be voted on by the holders of our common stock at the special meeting. As provided in its Schedule 13D filed on June 11, 2018, Knauf owns 14,757,258 shares of our common stock, which represents approximately 10.6% of the shares of our common stock issued and outstanding based on 139,462,508 shares of our common stock outstanding as of June 7, 2018 as represented in the merger agreement.

The USG board of directors unanimously recommends our stockholders vote “FOR” adoption of the merger agreement, “FOR” approval, on a non-binding, advisory basis, of the transaction-related named executive officer compensation, and “FOR” the adjournment proposal.

The accompanying proxy statement describes the merger agreement, the merger, the conditional special dividend and related matters, and attaches a copy of the merger agreement. We urge stockholders to read the entire proxy statement carefully, as it sets forth details of the merger agreement and other important information related to the merger and the conditional special dividend.

Your vote is very important. Whether or not you expect to attend the special meeting, we encourage you to vote your shares of our common stock as promptly as possible to make certain that you are represented at the special meeting. You may vote over the Internet, as well as by telephone or by mailing a proxy card or voting instruction card. If you are a “street name” holder (a holder whose shares of our common stock are held through a broker, bank or other nominee), for your shares of our common stock to be represented at the special meeting, you must instruct your broker, bank or other nominee as to how to vote your shares of our common stock by following the directions provided to you by your broker, bank or other nominee. The merger cannot be completed unless holders of at least 80 percent of the outstanding shares of our common stock entitled to vote at the special meeting vote “FOR” adoption of the merger agreement. Therefore, your failure to vote, abstention or failure to instruct your broker, bank or other nominee to vote, will have the same effect as a vote “AGAINST” adoption of the merger agreement. Failures to vote, abstentions and failures to instruct your broker, bank or other nominee to vote, will have no effect on the other proposals to be considered at the special meeting.

If you have any questions or need assistance voting your shares of our common stock, please contact D.F. King & Co., Inc., our proxy solicitor, by calling toll-free at (866) 745-0273 or collect at (212) 269-5550.

On behalf of the entire USG board of directors, we want to thank you for your continued support.

Neither the U.S. Securities and Exchange Commission nor any state securities regulatory agency has approved or disapproved the merger, passed upon the merits or fairness of the merger, the merger agreement or the other transactions contemplated thereby or passed upon the adequacy or accuracy of the disclosure in this document. Any representation to the contrary is a criminal offense.

This proxy statement is dated August 23, 2018 and is first being mailed to stockholders on or about August 23, 2018.

USG CORPORATION

550 West Adams Street

Chicago, Illinois 60661

Notice of Special Meeting of Stockholders

To Be Held on September 26, 2018

WHEN

September 26, 2018 at 9:00 a.m.,

Chicago Time

WHERE

USG Corporate Headquarters

550 West Adams Street

Chicago, Illinois 60661-3676

WHO CAN VOTE

Only stockholders of record at the close of business on August 21, 2018 will be entitled to vote at the special meeting, or any adjournment or postponement thereof (the “special meeting”).

At the special meeting, stockholders will be asked to consider and vote on the following proposals:

We will transact no other business at the special meeting except such business as may properly be brought before the special meeting. Please refer to the accompanying proxy statement for further information with respect to the business to be transacted at the special meeting. The accompanying proxy statement forms a part of this notice and is incorporated herein by reference.

RECOMMENDATION

After due consideration and discussion, the USG board of directors (the “Board”) unanimously (i) determined that the merger agreement, the merger and the other transactions contemplated by the merger agreement are fair to, advisable and in the best interests of the Company and its stockholders, (ii) approved and declared advisable the merger agreement and the completion by the Company of the transactions contemplated thereby, including the execution, performance and delivery of the merger agreement, (iii) subject to the merger agreement, resolved to recommend the adoption of the merger agreement and the transactions contemplated thereby by the Company’s stockholders, and (iv) directed that the merger agreement be submitted to the Company’s stockholders for adoption. The Board unanimously recommends you vote (1) “FOR” adoption of the merger agreement, (2) “FOR” approval, on a non-binding, advisory basis, of the transaction-related named executive officer compensation, and (3) “FOR” the adjournment proposal. If you sign, date and return your proxy card without indicating how you wish to vote on a proposal, your proxy will be voted “FOR” each of the foregoing proposals in accordance with the recommendation of the Board.

VOTING

The adoption of the merger agreement requires the affirmative vote of holders of at least 80 percent of the outstanding shares of our common stock, par value $0.10 per share (“common stock”), entitled to vote at the special meeting and is a condition to the completion of the merger. The approval, on a non-binding, advisory basis, of the transaction-related named executive officer compensation and the approval of the adjournment proposal each requires the affirmative vote of a majority of the shares of our common stock present in person or represented by proxy and entitled to vote on such proposal and which are actually so voted at the special meeting, but neither is a condition to the completion of the merger.

YOUR VOTE IS IMPORTANT, REGARDLESS OF THE NUMBER OF SHARES OF OUR COMMON STOCK YOU OWN. The merger cannot be completed unless the merger agreement is adopted by the affirmative vote of the holders of at least 80 percent of the outstanding shares of our common stock entitled to vote at the special meeting. EVEN IF YOU PLAN ON ATTENDING THE SPECIAL MEETING IN PERSON, WE REQUEST THAT YOU AUTHORIZE YOUR PROXY TO VOTE YOUR SHARES OF OUR COMMON STOCK BY EITHER MARKING, SIGNING, DATING AND PROMPTLY RETURNING THE PROXY CARD OR SUBMITTING YOUR PROXY OR VOTING INSTRUCTIONS BY TELEPHONE OR INTERNET, AS OUTLINED BELOW. If you attend the special meeting and desire to vote in person, you may do so even though you have previously sent in your proxy. The failure to vote, either in person or by proxy, abstention, or to provide voting instructions to your broker, will have the same effect as a vote “AGAINST” adoption of the merger agreement. Failure to vote, abstentions and broker non-votes will have no effect on the other proposals to be considered at the special meeting.

You can vote in person at the special meeting. For further information regarding attending the special meeting, see the section entitled “Special Meeting” in the accompanying proxy statement. Even if you plan to attend the meeting, please vote as soon as possible using one of the following methods:

Brokers may not vote your shares of our common stock on any of the matters being presented at the special meeting in the absence of specific voting instructions from you. Please contact your broker directly if you have questions about how to provide such instructions.

Under Delaware law, stockholders who do not vote “FOR” adoption of the merger agreement will have the right to seek appraisal of the fair value of their shares of our common stock as determined by the Delaware Court of Chancery if the merger is completed, but only if they submit a written demand for an appraisal before the vote on the proposal to adopt the merger agreement and comply with the other Delaware law procedures explained in the accompanying proxy statement. See the section entitled “Appraisal Rights” in the accompanying proxy statement.

You may revoke your proxy at any time before the vote at the special meeting by following the procedures outlined in the accompanying proxy statement.

Before voting your shares of our common stock, we urge you to, and you should, read the entire accompanying proxy statement carefully, including its annexes and the documents incorporated by reference in the proxy statement. If you have any questions concerning the merger, merger agreement, transaction-related named executive officer compensation, adjournment proposal, special meeting, conditional special dividend and related due bill trading or accompanying proxy statement, or if you would like additional copies of the accompanying proxy statement (at no charge) or need help submitting a proxy to have your shares of our common stock voted, please contact our proxy solicitor:

D.F. King & Co., Inc.

48 Wall Street

New York, NY 10005

Bankers and Brokers Call: (212) 269-5550

All Others Call: (866) 745-0273

Email: usg@dfking.com

MEETING ADMISSIONS:

An admission ticket (or other proof of stock ownership) and a form of photo identification will be required for admission to the special meeting. In addition, if you are not a stockholder of record but hold shares of our common stock through a broker, bank or other nominee (i.e., in street name), you will be required to provide proof of beneficial ownership as of the record date. See the section entitled “The Special Meeting” in the accompanying proxy statement.

DATE OF MAILING:

The proxy statement and the accompanying proxy card were first made available to our stockholders on or about August 23, 2018.

TABLE OF CONTENTS

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QUESTIONS AND ANSWERS ABOUT THE SPECIAL MEETING AND THE MERGER

The following questions and answers address briefly some questions you may have regarding the special meeting and the proposals to be voted on at the special meeting. These questions and answers may not address all of the questions that may be important to you as a stockholder of the Company. Please refer to the more detailed information contained elsewhere in this proxy statement, the annexes to this proxy statement and the documents referred to or incorporated by reference in this proxy statement, which you should read carefully and in their entirety. You may obtain the information incorporated by reference into this proxy statement without charge by following the instructions in the section entitled “Where You Can Find Additional Information.”

You are receiving this proxy statement as a stockholder of the Company in connection with the solicitation of proxies by the Board in favor of the proposal to adopt the merger agreement and to approve the other related matters to be voted on at the special meeting described below under “—What matters will be voted on at the special meeting?” The merger cannot be completed unless the merger agreement is adopted by holders of at least 80 percent of the outstanding shares of our common stock entitled to vote at the special meeting.

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For safety and security reasons, we will not allow anyone to bring large bags, briefcases or packages into the meeting room, or to record or photograph the meeting.

If you sign and submit your proxy card or voting instruction form but fail to provide voting instructions or abstain on any of the proposals listed on the proxy card, your shares of our common stock will be counted for the purpose of determining whether a quorum is established at the special meeting.

If your shares of our common stock are held in street name by your broker, bank or other nominee and you do not instruct that nominee how to vote your shares of our common stock, your broker, bank or other nominee will not vote on your behalf with respect to any of the proposals, and your shares of our common stock will not be counted for purposes of determining whether a quorum is established.

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Whether you hold shares of our common stock directly as a stockholder of record or as a street name stockholder (subject to specific instructions from your nominee as detailed below), you may direct how your shares of our common stock are voted by proxy without attending the special meeting. There are three ways to vote by proxy:

If your shares of our common stock are held by a broker, bank or other nominee on your behalf in street name, that nominee will send you instructions as to how to provide voting instructions for your shares of our common stock. Many brokerage firms and banks have a process for their customers to provide voting instructions by telephone or via the Internet, in addition to providing voting instructions by a voting instruction form. If you are a street name stockholder and you wish to vote your shares of our common stock in person at the special meeting, you must obtain a proxy from your broker, bank or other nominee giving you the right to vote your shares of our common stock at the meeting.

Unless you hold your shares of our common stock through the Investment Plan (as discussed below), you may vote via the Internet or by phone until 11:59 p.m. Eastern time, on September 25, 2018, or our Company’s agent must receive your paper proxy card on or before September 25, 2018.

For further information about how you may vote if you hold your shares of our common stock through the Investment Plan, see the information described below under “—If I hold shares through the USG Corporation Investment Plan, how do I vote?”

If you sign and submit your proxy card or voting instruction form without giving specific instructions on how to vote your shares of our common stock, in accordance with the recommendation of the Board, either our Chief Executive Officer or our Corporate Secretary will vote your shares of our common stock in the following manner:

For a discussion of the factors the Board considered in determining to recommend “FOR” adoption of the merger agreement, please see the section entitled “Proposal 1: The Merger—Recommendations of the Board

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and Reasons for the Merger.” In addition, in considering the recommendation of the Board with respect to the merger agreement, you should be aware that some of our directors and executive officers have interests that may be different from, or in addition to, the interests of our stockholders generally. For a discussion of these interests, please see the section entitled “Proposal 1: The Merger—Interests of Our Directors and Executive Officers in the Merger.”

The Investment Plan also provides that unallocated shares of our common stock and shares of our common stock for which no instructions are received by the Trustee will be voted by the Trustee in the same proportion as those shares of our common stock for which instructions are received, unless otherwise required by law. Thus, Investment Plan participants will be exercising power and control as a named fiduciary of the Investment Plan not only over the shares of our common stock allocated to their own accounts, but also over a portion of the undirected shares of our common stock. By submitting voting instructions over the Internet, by telephone or by signing and returning the proxy card accompanying this proxy statement, an Investment Plan participant will be directing the Trustee to vote the shares of our common stock allocated to his or her account under the Investment Plan, in person or by proxy, as instructed, at the special meeting. Investment Plan participants may revoke previously submitted voting instructions by phone, Internet or filing with Broadridge Financial Solutions, 51 Mercedes Way, Edgewood, New York 11717, the Investment Plan proxy tabulator, either a written notice of revocation or a properly completed and signed proxy card bearing a later date.

If you hold your shares of our common stock through the Investment Plan and you are also a stockholder of record, your proxy card will allow you to designate the manner in which you want both the shares of our common stock registered in your name and the shares of our common stock in the Investment Plan voted at the special meeting. If you hold your shares of our common stock through the Investment Plan, but you do not hold any shares of our common stock as a stockholder of record, you will be able to designate the manner in which you want those shares of our common stock voted at the special meeting by voting as described above.

If you own any of your shares of our common stock through the Investment Plan, you may vote via the Internet or by phone until 11:59 p.m., Eastern time, on September 23, 2018, or our Company’s agent must receive your paper proxy card on or before September 23, 2018.

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As they represent shares of our common stock issued and outstanding but will not be affirmatively voted to adopt the merger agreement, broker non-votes and abstentions will effectively count as votes “AGAINST” adoption of the merger agreement. As they are not votes actually cast on a given proposal, broker non-votes and abstentions will not affect the outcome of the vote to approve, on a non-binding, advisory basis, the transaction-related named executive officer compensation or the vote to approve the adjournment proposal.

For a discussion of the factors that the Board considered in determining to recommend “FOR” adoption of the merger agreement, please see the section entitled “Proposal 1: The Merger—Recommendations of the Board and Reasons for the Merger.” In addition, in considering the recommendation of the Board with respect to the merger agreement, you should be aware that some of our directors and executive officers have interests that may be different from, or in addition to, the interests of Company stockholders generally. For a discussion of these interests, please see the section entitled “Proposal 1: The Merger—Interests of Our Directors and Executive Officers in the Merger.”

Concurrently with the execution of the merger agreement, Knauf and Merger Sub entered into the voting agreement with Berkshire with respect to the subject shares. Under the voting agreement, Berkshire agreed, among other things and on the terms set forth therein, to vote (or cause to be voted) the subject shares then beneficially owned by Berkshire, directly or indirectly, “FOR” adoption of the merger agreement, approval of the merger and the consummation of all of the transactions contemplated thereby and against any competing acquisition proposals relating to the Company. As provided in its Schedule 13D filed on June 11, 2018, Berkshire owns 43,387,980 shares of our common stock, which represents approximately 31.1% of the shares of our common stock issued and outstanding based on 139,462,508 shares of our common stock outstanding as of June 7, 2018 as represented in the merger agreement.

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The voting agreement will terminate upon the earlier to occur of (i) the effective time of the merger, (ii) the date on which the merger agreement is terminated in accordance with its terms, (iii) five business days after delivery of written notice of termination by Berkshire to Knauf if after the date of the voting agreement any acquisition proposal relating to the Company has been publicly announced or otherwise becomes publicly known, (iv) the date of any material modification, amendment or waiver of or to the merger agreement as in effect as of the date of the voting agreement, which Berkshire believes has an adverse effect on the consideration payable to stockholders of the Company upon completion of the merger, (v) September 1, 2019 and (vi) the mutual written agreement of Knauf and Berkshire to terminate the voting agreement.

Due to the contingent nature of the conditional special dividend, the NYSE rules require our common stock to trade with “due bills,” representing an assignment of the right to receive the conditional special dividend, beginning on August 20, 2018 (one business day prior to the record date) through the date the conditional special dividend is paid (the “conditional special dividend payment date”) or the date it is determined that the conditional special dividend will not be paid because stockholder approval of the adoption of the merger agreement was not obtained (such period of time, the “due bill period”). Our common stock will not trade ex-dividend until the first business day after the conditional special dividend payment date (the “ex-dividend date”). This means that purchasers of our common stock during the due bill period that hold such shares of common stock on the conditional special dividend payment date are entitled to receive the conditional special dividend in the event stockholder approval of the adoption of the merger agreement is obtained. Stockholders that sell our common stock during the due bill period are not entitled to receive the conditional special dividend in the event stockholder approval of the adoption of the merger agreement is obtained. Investors who enter into trades to purchase our common stock on or after the ex-dividend date will not receive the conditional special dividend. The conditional special dividend is conditioned on the merger agreement being adopted by our stockholders at the special meeting and, if the merger agreement is so adopted, will be paid following certification of the results of the special meeting.

Due bills obligate sellers who were stockholders of record on the record date to deliver the conditional special dividend, if paid, to the subsequent buyer. Accordingly, holders of our common stock on the record date must hold our common stock through the conditional special dividend payment date to be entitled to receive the conditional special dividend. The due bill obligations are settled customarily between the brokers representing the buyers and sellers of our common stock. The Company has no obligations for either the amount of the due bill or the processing of the due bill. Buyers and sellers of our common stock during the due bill period should consult their broker before trading in our common stock to be sure they understand the effect of the NYSE’s due-bill procedures.

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Any Company DSU Awards held in notional accounts by non-employee directors will be converted into a right to receive a cash payment equal to the product of (i) the number of shares of our common stock deemed to be held in the notional account immediately before the effective time of the merger, multiplied by (ii) the closing consideration, at the earliest time permitted under the applicable award agreement and Section 409A of the Code following termination of the director’s service with the Company.

The Company will grant a Dividend Make-Whole Amount to each holder of Incentive Equity Awards that are not entitled to receive the conditional special dividend as a dividend equivalent, in the form of a cash payment in an amount equal to the product of (i) the conditional special dividend, multiplied by (ii) the number of shares of common stock that either (a) are or become vested and paid out on such Incentive Equity Awards in connection with the completion of the merger and did not otherwise participate in the conditional special dividend, or (b) subject to the applicability of due bill trading, are or become vested and become payable following the record date, but prior to completion of the merger, in each case as determined by the Company.

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In addition, Knauf, for purposes of any of its employee benefit plans in which Continuing USG Employees are eligible to participate following the completion of the merger, will recognize for purposes of eligibility, vesting and level of benefits each Continuing USG Employee’s years of service with the Company and its subsidiaries before the effective time of the merger, to the same extent as such employee was entitled, before the effective time of the merger, to credit for such service under any comparable Company benefit plan, unless (i) its application would result in a duplication of benefits, (ii) similarly situated employees of Knauf do not receive credit for such service, (iii) such Company benefit plans did not recognize such period of service or did not provide credit for prior service, or (iv) such Knauf benefit plan is a frozen or grandfathered plan. With respect to medical, dental or vision insurance benefits, for the plan year in which the Continuing USG Employees are first eligible to participate (i) any preexisting conditions or limitations and eligibility waiting periods will be waived with respect to the Continuing USG Employees and their eligible dependents to the extent such limitation would have been waived or satisfied under the Company benefit plan in which such Continuing USG Employee participated immediately prior to the merger, and (ii) the amount of eligible expenses incurred by each Continuing USG Employee and his or her eligible dependents that were credited to deductible and maximum out-of-pocket co-insurance requirements under the Company benefit plans immediately prior to the merger will be credited for purposes of satisfying the deductible and maximum out-of-pocket co-insurance requirements under the corresponding Knauf benefit plans.

Knauf’s obligations to provide such compensation and benefits to Continuing USG Employees who are covered by a collective bargaining agreement or based outside of the United States will be modified or adjusted as necessary to comply with the terms of such collective bargaining agreement or the laws of such countries in which such Continuing USG Employees are based.

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Notwithstanding the fact that, if the merger agreement is not adopted by our stockholders, or if the merger is not completed for any other reason, we will remain a public company, the UBBP joint venture partner may still exercise its call option right that was triggered as a result of entering into the merger agreement.

However, regardless of whether the merger is completed, if the merger agreement is nevertheless adopted by our stockholders at the special meeting, (i) promptly following certification of the results of the special meeting, the Company will pay the conditional special dividend to all holders of record of common stock as of the record date for the special meeting (subject to due bill trading as further described in this proxy statement), and (ii) each holder of any Company RSU Awards and any Company DSU Awards, outstanding as of the record date of the special meeting, that provide for dividend equivalents, will receive a dividend equivalent on account of such conditional special dividend in accordance with the terms of such award. However, if the merger is not completed, even if stockholder approval of the adoption of the merger agreement is obtained, no holder of any outstanding stock options, Company MSU Awards or Company Performance Share Awards will receive any payment on account of such conditional special dividend.

In the event that either we or Knauf terminates the merger agreement, then, in certain specified circumstances, we may be required to pay Knauf a termination fee in an amount equal to $215 million. See the section entitled “The Merger Agreement—Company Termination Fee” for more information.

The record date for stockholders entitled to vote at the special meeting is earlier than the expected completion of the merger. If you transfer your shares of our common stock after the record date but before the special meeting date, you will, unless special arrangements have been made, have the right to vote at the special meeting; however, if you transfer your shares of our common stock during the due bill period, as to those shares, you will not receive either the conditional special dividend in the event stockholder approval of the adoption of the merger agreement is obtained or the closing consideration.

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If you would like to change your householding election, request that a single copy of this or future proxy materials be sent to your address, or request a separate copy of this or future proxy materials, you should submit this request by writing Broadridge Financial Solutions, Inc., Householding Department, 51 Mercedes Way, Edgewood, New York, 11717, or calling 1-866-540-7095. We will promptly deliver the proxy materials to you upon receipt of your request. Beneficial owners sharing an address who are receiving multiple copies of the proxy materials and wish to receive a single copy of these materials in the future should contact their broker, bank or other nominee to make this request.

If you are a registered stockholder or hold shares of our common stock in the Investment Plan, we sent you and each registered Investment Plan holder at your address separate sets of proxy materials.

We have retained D.F. King & Co., Inc. (“D.F. King”) as proxy solicitation agent and information agent for the Company. We will pay the fees of D.F. King, which we expect to be approximately $250,000, plus reimbursement of out-of-pocket expenses and will indemnify D.F. King and all of its directors, officers, employees and agents against certain claims, expenses, losses, damages and/or liabilities.

We have retained Alliance Advisors, LLC to provide consulting services related to the special meeting for a fee of approximately $50,000 plus out-of-pocket expenses.

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D.F. King & Co., Inc.

48 Wall Street

New York, NY 10005

Bankers and Brokers Call: (212) 269-5550

All Others Call: (866) 745-0273

Email: usg@dfking.com

or

USG Corporation

Attn: Corporate Secretary

550 W. Adams Street

Chicago, IL 60661-3676

(312) 436-4000

If your broker, bank or other nominee holds your shares of our common stock, you should also call your broker, bank or other nominee for additional information.

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CAUTIONARY STATEMENT CONCERNING FORWARD-LOOKING STATEMENTS

These materials contain forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 related to management’s expectations about future conditions, including but not limited to, statements regarding the proposed transaction with Knauf, including expected timing, completion and effects of the proposed transaction. In some cases, forward-looking statements include, without limitation, any statement that may project, indicate or imply future results, events, performance or achievements, and may contain the words “expect,” “intend,” “plan,” “anticipate,” “estimate,” “believe,” “may,” “will be,” “will continue,” “will likely result” and similar expressions. Actual business, market or other conditions may differ materially from management’s expectations and, accordingly, may affect our sales and profitability, liquidity and future value. Any forward-looking statements represent our views only as of today and should not be relied upon as representing our views as of any subsequent date, and we undertake no obligation to update any forward-looking statement. Among the risks, contingencies and uncertainties that could cause actual results to differ from those described in the forward-looking statements or could result in the failure of the proposed transaction to be completed are the following: the failure to obtain stockholder approval of the adoption of the merger agreement; the failure to obtain necessary regulatory or other governmental approvals for the proposed transaction, or if obtained, the possibility of being subjected to conditions that could result in a material delay in, or the abandonment of, the proposed transaction or otherwise have an adverse effect on the Company; continued availability of financing or alternatives for the financing provided in the debt commitment letter; the failure to satisfy required closing conditions; the potential impact on the UBBP joint venture in the event the proposed transaction is not completed, including the risk that, in connection with the execution of the merger agreement, Boral Limited has the right to exercise its option to acquire the Company’s ownership of the UBBP joint venture; the risk that the proposed transaction may not be completed in the expected timeframe, or at all; the effect of restrictions placed on the Company and its subsidiaries’ ability to operate their businesses under the merger agreement, including the Company’s ability to pursue alternatives to the proposed transaction; the risk of disruption resulting from the proposed transaction, including the diversion of the Company’s resources and management’s attention from ongoing business operations; the effect of the announcement of the proposed transaction on the Company’s ability to retain and hire key employees; the effect of the announcement of the proposed transaction on the Company’s business relationships, results of operations, financial condition, the market price of the Company’s common stock and businesses generally; the risk of negative reactions from investors, employees, suppliers and customers; the outcome of any legal proceedings that may be instituted against the Company related to the proposed transaction; the amount of the costs, fees, expenses and charges related to the proposed transaction; and the occurrence of any event giving rise to the right of a party to terminate the merger agreement. Information describing other risks and uncertainties affecting the Company that could cause actual results to differ materially from those in forward-looking statements may be found in our filings with the SEC, including, but not limited to, the “Risk Factors” in our Annual Report on Form 10-K for the year ended December 31, 2017 and our Quarterly Report on Form 10-Q for the three months ended June 30, 2018.

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THE COMPANIES

USG Corporation

We are an industry-leading manufacturer of building products and innovative solutions. Headquartered in Chicago, we serve construction markets around the world through our Gypsum, Performance Materials, Ceilings, and USG Boral divisions. Our wall, ceiling, flooring, sheathing and roofing products provide the solutions that enable customers to build the outstanding spaces where people live, work and play. Our UBBP joint venture is a leading plasterboard and ceilings producer across Asia, Australasia and the Middle East.

The Company’s principal executive offices are located at 550 West Adams Street, Chicago, Illinois 60661-3676 and its telephone number is (312) 436-4000.

A detailed description of the Company’s business is contained in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2017, which is incorporated by reference into this proxy statement. See the section entitled “Where You Can Find Additional Information.”

Gebr. Knauf KG

Knauf is the ultimate parent company of the Knauf Group, which is headquartered in Iphofen, Germany. Knauf is a leading manufacturer of building materials operating more than 220 factories worldwide. In 2017, Knauf generated global revenues in excess of $8 billion and employed more than 27,000 people.

Knauf’s principal executive offices are located at Am Bahnhof 7, 97346 Iphofen, Federal Republic of Germany, and its telephone number is (49) 9329-31-1091.

World Cup Acquisition Corporation

Merger Sub is a Delaware corporation and an indirect, wholly-owned subsidiary of Knauf that will function as the merger subsidiary in the merger. Merger Sub has not carried on any activities on or prior to the date of this proxy statement except for activities incidental to its formation and activities in connection with Knauf’s acquisition of the Company. Upon completion of the merger, Merger Sub will merge with and into the Company and will cease to exist.

Merger Sub’s principal executive offices are located at Am Bahnhof 7, 97346 Iphofen, Federal Republic of Germany, and its telephone number is (49) 9329-31-1091.

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THE SPECIAL MEETING

We are furnishing this proxy statement to you as part of the solicitation of proxies by the Board for use at the special meeting. This proxy statement provides you with the information you need to know to be able to vote or instruct your vote to be cast at the special meeting.

Date, Time and Place of the Special Meeting

The special meeting will be held at 9:00 a.m., Chicago time, on September 26, 2018 at USG Corporate Headquarters, 550 West Adams Street, Chicago, Illinois 60661-3676.

For information regarding attending the special meeting, please see the section entitled “—Attendance; Voting; Proxies; Revocation—Attendance.”

Purposes of the Special Meeting

At the special meeting, you will be asked to consider and vote on the following proposals:

Our stockholders must adopt the merger agreement for the merger to occur. If our stockholders fail to adopt the merger agreement, the merger will not occur. A copy of the merger agreement is attached to this proxy statement as Annex A, and the material provisions of the merger agreement are described in the section entitled “The Merger Agreement.”

The non-binding, advisory vote on the transaction-related named executive officer compensation is a vote required by the rules of the SEC and is separate and apart from the vote to adopt the merger agreement. Accordingly, a stockholder may vote to approve, on a non-binding, advisory basis, the transaction-related named executive officer compensation and vote not to adopt the merger agreement and vice versa. Because the vote on the transaction-related named executive officer compensation is advisory in nature only, it will not be binding on either the Company or Knauf. Accordingly, if stockholder approval of the adoption of the merger agreement is obtained and the merger is completed, the transaction-related named executive officer compensation will be paid to our named executive officers in accordance with the terms of their compensation agreements and arrangements even if stockholders fail to approve this proposal.

The vote on the adjournment proposal is a vote separate and apart from the vote on the proposal to adopt the merger agreement. Accordingly, you may vote to approve the proposal to adopt the merger agreement and vote not to approve the adjournment proposal and vice versa. The Company does not anticipate calling a vote on the adjournment proposal if the merger agreement is first adopted by the requisite number of shares of our common stock at the special meeting.

We do not expect a vote to be taken on any other matters at the special meeting. If any other matters are properly presented at the special meeting for consideration, however, the holders of the proxies will have discretion to vote on these matters in accordance with their best judgment.

Record Date and Quorum

All record holders of our common stock at the close of business on the record date of August 21, 2018 are entitled to vote their shares of our common stock at the special meeting. On the record date, there were

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139,748,196 shares of our common stock issued and outstanding and entitled to vote. Each share of our common stock outstanding at the close of business on the record date is entitled to one vote on each of the proposals presented at the special meeting. The shares of our common stock are our only securities entitled to vote at the special meeting.

The presence at the special meeting, in person or represented by proxy, of the holders of a majority of the shares of our common stock issued and outstanding and entitled to vote at the special meeting will establish a quorum. If a quorum is not established at the special meeting, the special meeting may be adjourned or postponed from time to time (subject to the terms of the merger agreement) until a quorum is established.

If you sign and submit your proxy card or voting instruction form but fail to provide voting instructions or abstain on any of the proposals listed on the proxy card, your shares of our common stock will be included in the calculation of the number of shares of our common stock considered to be present at the special meeting for the purpose of determining whether a quorum is established.

If your shares of our common stock are held by you as the holder of record and you do not return your proxy card or otherwise vote your shares of our common stock by telephone or internet, your shares of our common stock will not be considered present at the special meeting for the purpose of determining whether a quorum is established.

If your shares of our common stock are held in street name and you do not instruct the nominee how to vote your shares of our common stock, your shares of our common stock will not be considered present at the special meeting for the purpose of determining whether a quorum is established.

Required Vote

Each share of our common stock outstanding at the close of business on the record date is entitled to one vote on each of the proposals to be considered at the special meeting.

Adoption of the merger agreement requires the affirmative vote of holders of at least 80 percent of the outstanding shares of our common stock entitled to vote at the special meeting. A failure to vote your shares of our common stock or an abstention from voting will have the same effect as a vote “AGAINST” the proposal to adopt the merger agreement. Approval, on a non-binding, advisory basis, of the transaction-related named executive officer compensation and approval of the adjournment proposal each require the affirmative vote of a majority of the shares of our common stock present in person or represented by proxy and entitled to vote on each such proposal and which are actually so voted at the special meeting. An abstention with respect to either proposal, or a failure to vote your shares of our common stock will have no effect on these proposals (assuming, in the case of a failure to vote, that a quorum is established).

Voting by the Company’s Directors and Executive Officers

At the close of business on the record date, our directors and executive officers were entitled to vote approximately 424,467 shares of our common stock, or approximately 0.3 percent of the shares of our common stock issued and outstanding on that date. We currently expect that our directors and executive officers will vote their shares of our common stock “FOR” adoption of the merger agreement and the other proposals to be considered at the special meeting, although they have no obligation to do so.

Voting by Knauf and Berkshire

Pursuant to the merger agreement, Knauf has agreed to vote, or cause any of its applicable subsidiaries to vote, in person or by proxy, all shares of our common stock held of record by Knauf, directly or indirectly, “FOR” adoption of the merger agreement and approval of the transaction-related named executive officer compensation, and any other action in furtherance thereof. As provided in its Schedule 13D filed on June 11,

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2018, Knauf owns 14,757,258 shares of our common stock, which represents approximately 10.6% of our common stock issued and outstanding based on 139,462,508 shares of our common stock outstanding as of June 7, 2018 as represented in the merger agreement.

Concurrently with the execution of the merger agreement, Knauf and Merger Sub entered into the voting agreement with Berkshire with respect to the subject shares. Under the voting agreement, Berkshire agreed, among other things and subject to the terms thereof, to vote (or cause to be voted) the subject shares then beneficially owned by Berkshire, directly or indirectly, “FOR” adoption of the merger agreement, approval of the merger and the consummation of all of the transactions contemplated thereby and against any competing acquisition proposals relating to the Company. As provided in its Schedule 13D filed on June 11, 2018, Berkshire owns 43,387,980 shares of our common stock, which represents approximately 31.1% of our common stock issued and outstanding based on 139,462,508 shares of our common stock outstanding as of June 7, 2018 as represented in the merger agreement.

As such, pursuant to the merger agreement and the voting agreement, respectively, Knauf and Berkshire will vote their shares of our common stock “FOR” adoption of the merger agreement and the other proposals to be considered at the special meeting. See the sections entitled “The Merger Agreement” and “The Voting Agreement.”

Attendance; Voting; Proxies; Revocation

Attendance

If you plan to attend the meeting, you must hold at least one share of common stock as of the record date. A form of photo identification will be required for admission to the special meeting as well as one of the following proofs of stock ownership:

Voting in Person

Stockholders of record will be able to vote in person at the special meeting. If you are a street name stockholder and you wish to vote your shares of our common stock in person at the special meeting, you must obtain a proxy from your broker, bank or other nominee giving you the right to vote your shares of our common stock at the special meeting. Attending the special meeting in person does not itself constitute a vote on any proposal.

Providing Voting Instructions by Proxy

To ensure that your shares of our common stock are voted at the special meeting, we recommend that you provide voting instructions promptly by proxy, even if you plan to attend the special meeting in person.

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Stockholders of Record and Street Name Stockholders

We have both stockholders of record, or registered stockholders, and street name stockholders. If your shares of our common stock are registered in your name with Computershare Trust Company N.A., our transfer agent, you are a stockholder of record or registered stockholder. You are a stockholder of record, for example, if you hold a certificate for your shares of our common stock. If your shares of our common stock are held in the name of a broker, bank or other nominee, you are a street name stockholder.

Whether you hold shares of our common stock directly as a stockholder of record or as a street name stockholder (subject to specific instructions from your nominee as detailed below), you may direct how your shares of our common stock are voted by proxy without attending the special meeting. There are three ways to vote by proxy:

Participants in the USG Corporation Investment Plan (401(k) Plan)

The Trustee of the Investment Plan held 265,481 shares of our common stock on the record date. Only the Trustee, as of the record date, can vote the shares of our common stock held by the Investment Plan. However, the Investment Plan provides that Investment Plan participants are entitled to instruct the Trustee how the shares of our common stock allocated to their accounts under the Investment Plan are to be voted.

The Investment Plan also provides that unallocated shares of our common stock and shares of our common stock for which no instructions are received by the Trustee will be voted by the Trustee in the same proportion as those shares of our common stock for which instructions are received, unless otherwise required by law. Thus, Investment Plan participants will be exercising power and control as a named fiduciary of the Investment Plan not only over the shares of our common stock allocated to their own accounts, but also over a portion of the undirected shares of our common stock. By submitting voting instructions over the Internet, by telephone or by signing and returning the proxy voting form accompanying this proxy statement, an Investment Plan participant will be directing the Trustee to vote the shares of our common stock allocated to his or her account under the Investment Plan, in person or by proxy, as instructed, at the special meeting. Investment Plan participants may revoke previously submitted voting instructions by phone, Internet or filing with Broadridge Financial Solutions, 51 Mercedes Way, Edgewood, New York 11717, the Investment Plan proxy tabulator, either a written notice of revocation or a properly completed and signed proxy card bearing a later date.

If you hold shares of our common stock through the Investment Plan and you are also a stockholder of record, your proxy card will allow you to designate the manner in which you want both the shares of our common stock registered in your name and the shares of our common stock in the Investment Plan voted at the

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special meeting. If you hold shares of our common stock through the Investment Plan, but you do not own any shares of our common stock as a stockholder of record, you will be able to designate the manner in which you want those shares of our common stock voted at the special meeting by voting as described above.

Shares of Our Common Stock Held in Street Name

If your shares of our common stock are held by a broker, bank or other nominee on your behalf in street name, your broker, bank or other nominee will send you instructions as to how to provide voting instructions for your shares of our common stock. Many brokerage firms and banks have a process for their customers to provide voting instructions by telephone or via the Internet, in addition to providing voting instructions by a voting instruction form.

In accordance with the rules of the NYSE, brokers, banks and other nominees that hold shares of our common stock in street name for their customers do not have discretionary authority to vote the shares of our common stock with respect to adoption of the merger agreement or the other proposals presented in this proxy statement. Accordingly, if brokers, banks, trust companies or other nominees do not receive specific voting instructions from the beneficial owner of such shares of our common stock, they may not vote such shares of our common stock with respect to these proposals. Therefore, unless you attend the special meeting in person with a properly executed legal proxy from your broker, bank or other nominee, your failure to provide instructions to your broker, bank or other nominee will result in your shares of our common stock not being present at the meeting and not being voted on any of the proposals.

Revocation of Proxies

Any person giving a proxy pursuant to this solicitation has the power to revoke and change it at any time before it is voted. If you are a stockholder of record, you may revoke your proxy at any time before the vote is taken at the special meeting by (i) giving written notice to our Corporate Secretary which must be received by us on or before September 25, 2018, (ii) voting in person at the special meeting, (iii) granting a subsequent proxy over the Internet or by telephone (you may not change your vote over the Internet or by telephone after 11:59 p.m., Eastern time, on September 25, 2018) or (iv) if you received your proxy materials by mail, submitting another signed proxy card with a date later than your previously delivered proxy. Simply attending the meeting will not, by itself, revoke your proxy; only your latest dated, valid proxy received not later than September 25, 2018 will be counted.

Please note that if you want to revoke your proxy by mailing a new proxy card to the Company or by sending a written notice of revocation to the Company, you should ensure that you send your new proxy card or written notice of revocation in sufficient time for it to be received by the Company before the special meeting.

If you hold your shares of our common stock in street name through a broker, bank or other nominee, you will need to follow the instructions provided to you by your broker, bank or other nominee in order to revoke your proxy or submit new voting instructions. If you hold your shares of our common stock in street name, you may also revoke a prior proxy by voting in person at the special meeting if you obtain a proxy executed in your favor from your broker, bank or other nominee in order to be able to vote in person at the special meeting. Investment Plan participants may revoke previously submitted voting instructions by phone, Internet or filing with Broadridge Financial Solutions, 51 Mercedes Way, Edgewood, New York 11717, the Investment Plan proxy tabulator, either a written notice of revocation or a properly completed and signed proxy card bearing a later date.

Abstentions

An abstention occurs when a stockholder attends a meeting, either in person or represented by proxy, but abstains from voting. Abstentions will be included in the calculation of the number of shares of our common stock present or represented at the special meeting for purposes of determining whether a quorum has been established.

Abstaining from voting will have the same effect as a vote “AGAINST” adoption of the merger agreement. The requisite number of shares of our common stock to approve the other proposals presented in this proxy

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statement is based on the total number of votes actually cast with respect to those proposals. If you abstain from voting, it will have no effect on the proposal to approve, on a non-binding, advisory basis, the transaction-related named executive officer compensation or the adjournment proposal.

Solicitation of Proxies

The Board is soliciting your proxy, and the Company will bear the cost of this solicitation of proxies. This includes the charges and expenses of brokerage firms and others for forwarding the proxy solicitation materials to beneficial owners of the common stock.

The Company has retained D.F. King, a proxy solicitation firm, to assist the Board in the solicitation of proxies for the special meeting, and we expect to pay D.F. King approximately $250,000, plus reimbursement of out-of-pocket expenses. Proxies may be solicited by mail, personal interview, e-mail, telephone or via the Internet by D.F. King or, without additional compensation, by certain of the Company’s directors, officers and employees.

We have retained Alliance Advisors, LLC to provide consulting services related to the special meeting for a fee of approximately $50,000 plus out-of-pocket expenses.

Other Information

You should not return your stock certificates or send documents representing your shares of our common stock with the proxy card. If the merger is completed, the paying agent for the merger will send you a letter of transmittal and related materials and instructions for exchanging your shares of our common stock for the closing consideration.

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PROPOSAL 1: THE MERGER

The description of the merger in this section and elsewhere in this proxy statement is qualified in its entirety by reference to the complete text of the merger agreement, a copy of which is attached as Annex A and is incorporated by reference into this proxy statement. This summary does not purport to be complete and may not contain all of the information about the merger that is important to you. You are encouraged to read the merger agreement carefully and in its entirety.

Certain Effects of the Merger

Pursuant to the terms of the merger agreement, if the merger agreement is adopted by the Company’s stockholders and the other conditions to the completion of the merger are satisfied or waived, Merger Sub will be merged with and into the Company, with the Company surviving the merger as an indirect, wholly-owned subsidiary of Knauf.

The total consideration to be received by our stockholders in connection with the merger, consists of both the closing consideration and the conditional special dividend. Upon the terms and subject to the conditions of the merger agreement, at the effective time of the merger, each share of our common stock issued and outstanding immediately prior to the effective time of the merger (other than shares of our common stock owned by Knauf and its subsidiaries, the Company and its subsidiaries or excluded holders) automatically will be converted into the right to receive the closing consideration. In addition to the closing consideration, as contemplated in the merger agreement, the Company declared the conditional special dividend payable to holders of our common stock as of the record date of the special meeting (subject to due bill trading as further described in this proxy statement). Payment of the conditional special dividend is conditioned on obtaining stockholder approval of the adoption of the merger agreement and, if the merger agreement is so adopted, will be paid following certification of the results of the special meeting. The payment of the conditional special dividend is not conditioned on completion of the merger and, if stockholder approval of the adoption of the merger agreement is obtained, will be paid regardless of whether the merger is completed.

With respect to Incentive Equity Awards, because, by their terms, they are not entitled to receive dividend equivalents in respect of the conditional special dividend, the Company will grant Dividend Make-Whole Amount payments in an amount equal to the product of (i) the conditional special dividend, multiplied by (ii) the number of shares of common stock that either (a) are or become vested and paid out on such Incentive Equity Awards in connection with the completion of the merger and did not otherwise participate in the conditional special dividend, or (b) subject to the applicability of due bill trading, are or become vested and become payable following the record date, but prior to the closing date of the merger, in each case as determined by the Company. The Dividend Make-Whole Amount will be earned upon the effective time of the merger subject to the holder of the underlying Incentive Equity Awards remaining continuously employed by the Company and its subsidiaries until immediately prior to the effective time of the merger, and will be paid promptly thereafter, but in no event later than 15 days following the effective time of the merger. However, if any holder of outstanding Incentive Equity Awards terminates employment with, or providing services to, the Company or any of its subsidiaries prior to the effective time of the merger, and any such Incentive Equity Awards remain outstanding following such termination in accordance with their terms, then such holder will still be eligible to receive a Dividend Make-Whole Amount with respect to such outstanding Incentive Equity Awards. For discussion of the impact of the merger, including the closing consideration and the conditional special dividend, on each outstanding Company stock option, Company RSU Award, Company MSU Award, Company Performance Share Award and Company DSU Award in the merger, see the section entitled “The Merger Agreement—Treatment of Company Equity Awards.”

Our common stock is currently registered under the Exchange Act and is listed on the NYSE and the CHX under the symbol “USG.” As a result of the merger, the Company will cease to be a publicly-traded company and will be indirectly, wholly-owned by Knauf. Following the completion of the merger, all shares of our common stock will be delisted from the NYSE and the CHX and deregistered under the Exchange Act, and the Company

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will no longer be required to file periodic reports with the SEC with respect to its common stock in accordance with applicable law, rules and regulations.

Background of the Merger

The Company’s senior management and the Board regularly review the Company’s performance, strategy, competitive position, opportunities and prospects in light of the current business and economic environments, as well as developments in the housing and construction industry and the opportunities and challenges facing participants in that industry. These reviews have included consideration by the Company’s senior management and the Board, and discussions with industry participants from time to time, of potential strategic alternatives, including acquisitions, joint ventures and business combinations or other strategic transactions, as well as remaining an independent publicly-traded company.

Knauf initially invested in the Company in October 2000 and has been a stockholder of the Company since that time. As provided in its Schedule 13D filed on June 11, 2018, Knauf owns 14,757,258 shares of our common stock, which represents approximately 10.6% of our common stock issued and outstanding based on 139,462,508 shares of Company common stock outstanding as of June 7, 2018 as represented in the merger agreement.

From time to time, representatives of Knauf have met with the Company’s senior management to discuss Knauf’s investment in the Company and opportunities for various transactions between the two companies. In 2001, Knauf and the Company formed a joint venture (the “Knauf joint venture”) to manufacture and distribute Aquapanel^® brand concrete panels throughout Europe (excluding Turkey) and the countries of the former Soviet Union. In 2008, at the time the Company was exploring an equity offering, Knauf approached the Company about acquiring an additional equity interest in the Company with a path to acquiring a controlling interest in the Company and possibly eventually acquiring full ownership of the Company. Knauf ultimately declined to participate in the equity offering. In 2012, Knauf acquired the Company’s ceilings and surfaces business in Europe for approximately $80 million in cash. Knauf acquired the Company’s 50% interest in the Knauf joint venture in December 2015 for a total purchase price of approximately EUR48 million in cash. Knauf also explored from time to time the possibility of closer commercial cooperation between Knauf and the Company, although these discussions did not lead to additional commercial transactions or agreements.

At a meeting on January 25, 2017 between Alexander Knauf and Manfred Grundke, the general partners of Knauf, acting as representatives of Knauf, and Jennifer F. Scanlon, the Company’s President and Chief Executive Officer, and Matthew F. Hilzinger, the Company’s Executive Vice President and Chief Financial Officer, acting as representatives of the Company, Mr. Knauf and Mr. Grundke indicated that Knauf was interested in looking for ways to partner with the Company, including with respect to Knauf’s North American fiberglass insulation business.

On February 8, 2017, the Board held a previously scheduled in-person meeting during which Ms. Scanlon updated the Board on the January 25, 2017 meeting with Mr. Knauf and Mr. Grundke and noted that Knauf may be considering entering the U.S. wallboard market following their acquisition of a wallboard plant in Mexico.

On February 9, 2017, the Company confirmed to Knauf that the Board had been informed of Knauf’s interest in continuing to look to ways to partner, but that the Company would not be in a position to respond until it had completed its pending strategic business review process that was expected to be completed mid-year 2017.

On September 19, 2017, Ms. Scanlon and Mr. Hilzinger met with Mr. Knauf and Mr. Grundke during a visit to the United States. At the meeting, the Company informed Knauf that, based on the results of its strategic business review, the Company did not see strategic value in combining with an insulation business in North America. Mr. Knauf expressed disappointment that the Company did not see any synergy value in partnering with an insulation business, but did not make any alternative proposals.

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On November 29, 2017, at the request of Knauf, Mr. Knauf, Mr. Grundke and Jörg Schanow, Knauf’s general counsel, met in Chicago, Illinois with Ms. Scanlon, Mr. Hilzinger and Michelle M. Warner, Senior Vice President, General Counsel and Corporate Secretary of the Company. In requesting the meeting, Mr. Knauf stated that the purpose was to discuss an important stockholder issue. During the meeting, Knauf’s representatives stated Knauf’s intention to make a proposal to acquire the Company in an all-cash transaction. At the conclusion of this meeting, Knauf delivered an indicative and non-binding proposal, dated November 28, 2017, to the Company providing for the acquisition of all of the outstanding shares of the Company not currently owned by Knauf at a cash purchase price of $40.10 per share.

On December 15, 2017, the Board held an in-person meeting, with members of the Company’s senior management team and representatives of Jones Day, the Company’s legal counsel, and Goldman Sachs and J.P. Morgan, the Company’s financial advisors, to evaluate the unsolicited non-binding proposal from Knauf. The Board received a presentation from representatives of Jones Day regarding, among other things, the Board’s fiduciary duties in the context of considering an unsolicited proposal, the Company’s corporate governance profile and defenses available in the event of a hostile tender offer by Knauf or others, and types of processes that could be conducted if the Board determined to commence a process regarding a potential sale of the Company in order to seek to obtain a value-maximizing proposal. Representatives of Goldman Sachs and J.P. Morgan provided an overview of certain timing and strategy considerations and an overview of the financial aspects of the unsolicited proposal from Knauf. Representatives of Goldman Sachs also confirmed that Goldman Sachs’ Investment Banking Division had not provided Knauf financial advisory or underwriting services in the past 2 years and that Goldman Sachs had concluded that, in its opinion, nothing would limit its ability to fulfill its responsibilities as financial advisor to the Company in connection with the Knauf situation. Representatives of J.P. Morgan also confirmed that J.P. Morgan’s Investment Banking Division had not provided Knauf financial advisory or underwriting services in the past 2 years and that J.P. Morgan had concluded that, in its opinion, nothing would limit its ability to fulfill its responsibilities as financial advisor to the Company in connection with the Knauf situation. The Company’s senior management presented the Board with an overview of the Company’s history with Knauf, and a discussion followed regarding the relationship of the Company with Knauf and the history of Knauf’s investment in the Company. An overview of the Knauf business, its financial position and its pending acquisition of the ceilings business of Armstrong World Industries, Inc. in Europe and Asia was also discussed. Representatives of Goldman Sachs and J.P. Morgan then discussed preliminary financial analyses. The Company’s senior management noted that the Company was experiencing positive momentum in the fourth quarter and expressed confidence in the Company’s long-range plan. Representatives of Goldman Sachs and J.P. Morgan also reviewed other potential buyers and the possibility of their interest and ability to execute a transaction.

During the meeting, the Board also discussed with the Company’s senior management and the Company’s advisors what factors Knauf might have considered in setting its offered per share price. The participants in the meeting also discussed factors that would likely impact transaction certainty and certain risks relating to our UBBP joint venture and the joint venture partner’s call option rights under the UBBP shareholders agreement (as defined below). The participants in the meeting also discussed considerations relating to Berkshire Hathaway’s direct or indirect ownership of approximately 30% of our common stock and the fact that Berkshire Hathaway practically was unable to exit at the market price given its large position. Representatives from Jones Day also explained to the Board that its fiduciary duties ran to all stockholders. Following careful consideration of the information presented to the Board, the Board unanimously determined that Knauf’s unsolicited proposal was inadequate and insufficient to warrant further discussion. No decision was reached as to what per share price would result in a willingness to engage with Knauf. In addition, the Board requested that the Company’s senior management reach out to Berkshire Hathaway for the limited purpose of eliciting information about Berkshire Hathaway’s interactions with Knauf and that the Board be updated on the outcome of that conversation prior to any formal response to Knauf. The Board also directed the Company’s senior management to engage a public relations firm to prepare for any necessary public communications in connection with the unsolicited proposal.

On December 19, 2017, Ms. Scanlon and Ms. Warner had a call with Warren Buffett, the Chairman of the Board of Berkshire Hathaway, during which Mr. Buffett acknowledged that the conversation would be subject to

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confidentiality obligations and stated that Berkshire Hathaway had communicated with representatives from Knauf’s financial advisors, Morgan Stanley, as recently as that morning. Mr. Buffett also stated that while he was supportive of an all cash offer, he felt that Knauf would and should increase its price beyond $40.10 per share. Mr. Buffett also noted that he had communicated to Knauf that he would not support a transaction that treated Berkshire Hathaway differently from other stockholders. Ms. Scanlon informed Mr. Buffett that the Board had taken Knauf’s proposal seriously and had engaged financial advisors and legal counsel. She also informed Mr. Buffett that the Board had determined that the per share price proposed by Knauf did not adequately reflect the Company’s intrinsic value. Mr. Buffett encouraged the Company’s senior management to engage in good faith negotiations with Knauf to increase the per share price of Knauf’s proposal. Ms. Scanlon stated that the Board would consider any bona fide offer that reflected the Company’s intrinsic value. Subsequent to the discussion with Mr. Buffett, Ms. Scanlon provided an update to the Board on December 19, 2017 and confirmed the content of the response to be sent to Knauf the following morning.

On December 20, 2017, the Company provided a written response to Knauf indicating that the Board, in consultation with its financial and legal advisors, had considered Knauf’s proposal and had determined that the per share purchase price was wholly inadequate given the Company’s intrinsic value and therefore it was not in the best interest of the Company’s stockholders.

Following receipt of the Company’s response, on December 22, 2017, Mr. Knauf and Mr. Grundke spoke by phone with Ms. Scanlon and Mr. Hilzinger. During this call, the Company confirmed that the offered price of $40.10 per share was insufficient to warrant substantive discussions or granting Knauf access to the Company’s non-public information, particularly in light of the fact that Knauf competes with the Company. Ms. Scanlon explained certain factors the Board considered in determining the Company’s intrinsic value, as well as how the Board viewed U.S. tax reform. Ms. Scanlon noted that Knauf could learn more about the Company’s strategy by attending the Investor Day scheduled for March 8, 2018. She also noted that Knauf would need to offer a higher value before the Company’s senior management would be authorized to share non-public information and that the Board would consider all bona fide proposals that reflected the Company’s intrinsic value.

On February 1, 2018, the Company issued a press release disclosing its fourth quarter and full year 2017 results, provided its outlook on market conditions and other factors for 2018, described its new reporting segment structure and announced an increase in its share repurchase program.

On February 8, 2018, Mr. Knauf contacted Steven F. Leer, the Company’s non-executive Chairman of the Board, noting that, as a major stockholder of the Company, Knauf was interested in establishing a relationship with the Chairman of the Board and suggesting a meeting in late February. Due to scheduling conflicts, the parties were not able to meet until March 12, 2018.

As previously announced on November 16, 2017, the Company held an inaugural “Investor Day” presentation on March 8, 2018, during which the Company, among other matters, disclosed certain financial projections through the end of the Company’s 2020 fiscal year. Representatives from Knauf and Morgan Stanley attended the presentation.

On March 12, 2018, Mr. Leer and Ms. Scanlon met with Mr. Knauf and Mr. Grundke in New York. Mr. Knauf and Mr. Grundke reiterated Knauf’s determination to pursue a transaction and indicated that a revised proposal would be forthcoming, and that, although Knauf preferred to keep discussions regarding their proposal friendly, Knauf would consider approaching the Company’s stockholders directly through a public acquisition proposal. Mr. Leer and Ms. Scanlon assured Mr. Knauf and Mr. Grundke that the Board would consider a revised proposal in good faith and consistent with the Board’s fiduciary duties to all stockholders.

On March 15, 2018, Knauf delivered a revised indicative and non-binding proposal to the Company providing for the acquisition of all of the outstanding shares of the Company not currently owned by Knauf at a cash purchase price of $42.00 per share.

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On March 23, 2018, the Board held a previously scheduled in-person meeting, with members of the Company’s senior management and representatives of Jones Day, Goldman Sachs and J.P. Morgan, to discuss the revised proposal submitted by Knauf. Jones Day reviewed with the Board the fiduciary duties of directors in the context of the revised proposal. Representatives of Goldman Sachs reviewed with the Board the key terms in the revised proposal from Knauf. Goldman Sachs also reviewed changes to certain financial analyses since December 2017, noting that since then there had been an increase in the Company’s 52-week high stock price, as well as an increase in the median and highest analyst target stock prices. The discussion then turned to a review by Goldman Sachs and J.P. Morgan of their preliminary financial analyses and certain inputs that had changed since December 2017 based on market changes and other factors, including the passage of U.S. tax reform. The discussion then turned to a review of other potentially interested parties and the potential for alternative proposals if the Board determined to engage in discussions with Knauf regarding a potential transaction. The Board, members of the Company’s senior management and the advisors also discussed certain possible transaction complexities that could arise relating to the Company’s UBBP joint venture, the fact that Berkshire Hathaway was positioned differently than the Company’s other stockholders and would need to take a substantial discount to market to exit its position in the Company’s stock in the absence of a sale of the Company, the supermajority vote required by the Company’s stockholders to approve a merger with Knauf and possible actions by Knauf or other stockholders to attempt to acquire the Company for less than its intrinsic value.

The Board then discussed with the Company’s senior management and representatives of Jones Day, Goldman Sachs and J.P. Morgan the possible responses to Knauf’s revised proposal and methods to give Knauf additional direction that could cause Knauf to meaningfully improve its proposal to better reflect the Company’s intrinsic value, including the strategy of rejecting Knauf’s offer so that Knauf would further increase its proposal. The discussion then turned to challenges facing the Company that were highlighted in the fourth quarter 2017 earnings call and again at its Investor Day held on March 8, 2018. Following discussion in executive session and careful evaluation of the matters discussed during the Board meeting, the Board unanimously determined that Knauf’s revised proposal of $42.00 per share was wholly inadequate. The Board authorized Ms. Scanlon to send a written response to Knauf rejecting the current $42.00 proposal, while also providing additional information regarding the elements of the Company’s business plan that the Board believed supported a higher intrinsic value for the Company. The Board also authorized Ms. Scanlon to speak with Knauf’s senior management team and authorized a meeting among the Company’s financial advisors with Knauf’s financial advisors if a meeting would be useful to assist Knauf in meaningfully improving its proposal. The Board discussed a potential range of values but did not make a determination regarding what share price would warrant substantive discussions or granting Knauf access to the Company’s non-public information.

Before a formal written response had been finalized, Mr. Knauf called Ms. Scanlon on the evening of March 25, 2018 to inform her that Berkshire Hathaway was planning to file an amendment to its Schedule 13D prior to the market open on March 26, 2018 to disclose that Berkshire Hathaway on March 23, 2018 had offered Knauf an option to purchase all of the shares of the Company held by Berkshire Hathaway and its affiliates. Mr. Knauf noted that Knauf would also be filing an amendment to its Schedule 13D prior to market open to disclose the option arrangement proposed by Berkshire Hathaway as well as Knauf’s proposals to purchase all of the outstanding shares of the Company. Later that evening Berkshire Hathaway’s outside counsel provided a draft of Berkshire Hathaway’s Schedule 13D amendment to Jones Day.

Early on the morning of March 26, 2018, Knauf and Berkshire Hathaway and its affiliates filed amended Schedule 13Ds disclosing that, on March 23, 2018, at the request of Berkshire Hathaway, Mr. Knauf and Mr. Grundke, together with representatives of Morgan Stanley, held a telephonic discussion with Mr. Buffett and Todd Combs, Investment Officer of Berkshire Hathaway. During the call, Berkshire Hathaway proposed to grant Knauf an option to purchase all of the shares of our common stock held by Berkshire Hathaway and its affiliates. The option would be exercisable only in connection with the consummation of the purchase by Knauf of all of the outstanding shares of our common stock at a price of not less than $42.00 per share within six months. The option exercise price payable to Berkshire Hathaway would be the same price paid to the Company’s other stockholders by Knauf, less an option purchase price of $2.00 per share to be paid by

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Knauf to Berkshire Hathaway upon the grant of the option. Knauf’s amended Schedule 13D disclosed that no agreement, written or otherwise, was entered into between Knauf and Berkshire Hathaway relating to this proposal. Knauf’s amended Schedule 13D also disclosed the initial proposal that Knauf delivered to the Company on November 29, 2017 and the revised proposal that Knauf delivered to the Company on March 15, 2018.

Also on March 26, 2018, the Company delivered a letter to Knauf indicating that the Board had, together with the Company’s legal and financial advisors, thoroughly analyzed Knauf’s most recent proposal and unanimously determined that $42.00 per share was wholly inadequate, as it substantially undervalued the Company and was not in the best interests of all of the Company’s stockholders. That same day, the Company issued a press release disclosing that it had received an unsolicited, non-binding proposal from Knauf to acquire the Company and that the Board had unanimously rejected Knauf’s proposal. The press release further disclosed that the Board carefully evaluated the proposal and determined that it substantially undervalued the Company and was not in the best interests of all of the Company’s stockholders.

On March 29, 2018, Ms. Scanlon spoke telephonically with Mr. Knauf. Ms. Scanlon suggested that Knauf’s financial advisors meet with the Company’s financial advisors to discuss the Company’s views regarding valuation to assist Knauf in evaluating an increase to its current offer price. During the discussion, Mr. Knauf reiterated that Knauf might be willing to increase its offer price if the Company provided additional information and that Knauf would be willing to enter into a confidentiality agreement with the Company. Mr. Knauf proposed another in-person meeting with Mr. Leer and Ms. Scanlon and possibly one financial advisor from each party for the Company to present its strategic plan. Ms. Scanlon again reiterated that the Board would engage around any bona fide proposal that reflects the Company’s intrinsic value, and offered to have a meeting between the respective financial advisors to discuss the Company’s views on value. Mr. Knauf and Ms. Scanlon ultimately agreed to a meeting between the parties’ respective financial advisors. Later that same day Ms. Scanlon updated the Board on her conversation with Mr. Knauf. The Board requested that legal counsel attend any meeting of financial advisors given the competitive concerns and also confirmed that the purpose of the meeting was not to negotiate value, but to provide insights on how the parties were thinking about intrinsic value.

On that same day, the Company filed its annual report for fiscal year 2017 and its definitive proxy materials in connection with its 2018 annual meeting of stockholders.

Also on March 29, 2018, representatives of Company A contacted Ms. Scanlon to express interest in exploring a possible strategic transaction with the Company and suggested a meeting with representatives of the Company.

On April 4, 2018, Knauf delivered an information demand (dated April 3, 2018) to the Company pursuant to Section 220 of the DGCL requesting a list of the Company’s stockholders as of the record date for the 2018 annual meeting of stockholders and certain other information relating to stockholder voting at the 2018 annual meeting of stockholders for the purpose of communicating with the Company’s stockholders with respect to matters relating to their mutual interests as stockholders, including the solicitation of proxies for the election of directors in connection with the annual meeting.

On April 5, 2018, representatives of Goldman Sachs, J.P. Morgan and Jones Day met with representatives of Morgan Stanley and Baker McKenzie, Knauf’s legal advisor, in New York to discuss Knauf’s revised proposal and the Board’s response. During this meeting, the Company’s advisors described generally the valuation methodologies used by the Board to evaluate Knauf’s proposals. Knauf’s advisors indicated that in order to revisit value, Knauf would need to receive additional information that supports value beyond $42.00 per share. The Company’s advisors again reiterated that Knauf’s proposed price was not within a range to support the additional costs and distraction to the Company of engaging in a diligence process with Knauf or the risks to the Company of sharing material non-public information with a strategic competitor, and it did not appear that Knauf would be willing to propose a price per share that would be reflective of the Board’s view of the intrinsic value of the Company. At this same meeting, the Company’s advisors asked Knauf’s advisors what Knauf’s intention was

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in its delivery of the information demand letter. Knauf’s legal counsel indicated that the information demand was simply intended to preserve Knauf’s options. Knauf’s advisors suggested that the Board consider providing at least limited additional information relating to certain specific business and financial topics discussed during the meeting to potentially facilitate further discussions between the parties regarding valuation. Knauf’s advisors again confirmed Knauf’s willingness to enter into a confidentiality agreement with respect to the requested information.

Also on April 5, 2018, Ms. Scanlon spoke with Mr. Buffett to provide him with a confidential update on the engagement with Knauf to date. Ms. Scanlon stated that the Board’s view was that the interactions between the Company and Knauf constituted a negotiation, but that the Board simply had a different view as to the price at which the Company should share confidential information with Knauf. Mr. Buffett encouraged continued engagement and thought that the stockholders of the Company should decide whether the Company should be sold. He stated that he thought the stockholders would approve a transaction and indicated that he thought Knauf might have some room to improve its proposal if it wanted to get a transaction done. Mr. Buffett confirmed that his outside legal advisors were engaging with Knauf on the option offer that Berkshire Hathaway had previously made to Knauf, but that he was willing to extend the same option to another bidder if one emerged. Mr. Buffett reconfirmed that Berkshire Hathaway was not looking for a special deal for itself and also confirmed that the option did not extend to Berkshire Hathaway’s voting rights outside of a sale to Knauf.

On April 8, 2018, Ms. Scanlon met with the Chief Executive Officer of Company A to further explore Company A’s interest in a possible strategic transaction with the Company. During that meeting, Ms. Scanlon agreed to send representatives of the Company to meet with representatives of Company A during the week of April 23, 2018 to further explore possible benefits of a strategic transaction based on non-confidential information regarding the Company.

On April 9, 2018, Ms. Scanlon updated the Board on the meeting of the financial advisors on April 5, 2018, as well as on her conversations with Berkshire Hathaway and with Company A. The directors attending the call, which were a majority of the Board, confirmed their support for sharing non-confidential information with Company A to help it determine if there was a basis for further engagement.

On April 10, 2018, the Company delivered a letter to Knauf, which responded to Knauf’s information demand indicating that the information demand did not comply with the requirements of Delaware law.

Also on April 10, 2018, Knauf issued a press release announcing its intention to solicit proxies from the Company’s stockholders in connection with the 2018 annual meeting of stockholders and filed its preliminary proxy materials in connection with its campaign to solicit votes against the Company’s four director nominees (the “vote against campaign”). Knauf indicated in its materials that a vote “against” the Company’s directors would serve as a message to the Board to engage immediately in discussions with Knauf regarding its outstanding offer of $42.00 per share. Knauf did not propose alternative Board nominees.

On April 11, 2018, Knauf delivered a letter to the Board regarding its information demand along with supplemental information to satisfy the information requirements under Delaware law, and the Company responded on April 16, 2018, in accordance with Delaware law, that it would provide the requested information.

On April 12, 2018, Berkshire Hathaway filed an amended Schedule 13D, which disclosed that in response to an inquiry from a Bloomberg News reporter, a spokesperson for Berkshire Hathaway had indicated that Berkshire Hathaway intended to vote against the Company’s four director nominees.

On that same day, the Company provided a letter to its stockholders urging them to vote for the election of the Company’s four director nominees at the Company’s 2018 annual meeting of stockholders. The letter to stockholders indicated that although the Board had not made a decision to sell the Company, it remained open to

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evaluating any proposal to acquire the Company, as it had done with Knauf’s proposals, and that if Knauf, or any other viable bidder, made a proposal that reflected the Company’s intrinsic value, the Board would seek to negotiate an appropriate confidentiality arrangement to allow it to share information with the potential counterparty. The letter further explained that the Board had declined to share confidential information with Knauf because, in addition to being a competitor, Knauf’s acquisition proposal was not at a value that the Board believed at the time would adequately compensate all the Company’s stockholders.

Also on April 12, 2018, in response to a request from a stockholder of the Company, representatives of Goldman Sachs and J.P. Morgan had a call with representatives of Company B to discuss Company B’s potential interest in making a proposal for the Company. On the call, the Company B representatives expressed that they did not see a basis for making a competitive proposal.

On April 16, 2018, the Board and representatives of Jones Day, Goldman Sachs and J.P. Morgan held an update call to discuss the vote against campaign, the Company’s response and Berkshire Hathaway’s voting intent. Representatives of Jones Day reviewed the Board’s legal obligations and also provided an update on the possible outcome of a vote against the director nominees. Ms. Scanlon noted that the Company was likely to miss first quarter 2018 consensus earnings, but expected to be on plan for the year. She also provided a brief update on the upcoming conversations with Company A. The directors attending the call, which were a majority of the Board, discussed their views on the input from stockholders and possible next steps with respect to exploring strategic alternatives.

On April 20, 2018, Knauf filed its definitive proxy materials in connection with its vote against campaign. On the same day, the Company filed its amended proxy materials relating to the vote against campaign.

On April 23, 2018, members of the Company’s senior management met in-person with management from Company A to discuss Company A’s potential interest in making a proposal for the Company. Management from Company A indicated that they would assess over the next week whether there was a business case for a potential transaction.

On April 25, 2018, the Company issued a press release announcing its first quarter 2018 results. On the same day, the Company filed its quarterly report on Form 10-Q. The following day, Knauf issued a press release related to the Company’s first quarter 2018 earnings and reaffirming its proposal to acquire the Company for $42.00 per share. The Company also filed a letter to its stockholders, which among other things, outlined its disagreements with Knauf’s public statements and reiterated the Board’s view that Knauf’s proposal did not represent the intrinsic value of the Company.

Also on April 25, 2018, the Board convened a telephonic meeting, along with members of the Company’s senior management and representatives of Jones Day, Goldman Sachs and J.P. Morgan, to discuss the vote against campaign and input the Company had received from several of the Company’s significant stockholders who had expressed the view that the Company should engage in further discussion with Knauf to explore a possible transaction. The discussion then turned to the possibility of receiving a competing offer from Company A. The parties then discussed possible actions by Knauf leading up to and following the 2018 annual meeting of stockholders, depending on the outcome of the vote against campaign. The Board, together with senior management and representatives of Jones Day, Goldman Sachs and J.P. Morgan, discussed the pros and cons of engaging with Knauf or waiting until the Company received further information regarding Company A’s interest. Following the discussion, the Board determined to discuss further actions at a later date.

During the month of April, Ms. Scanlon also had discussions with the respective Chief Executive Officers of Company C and Company D, each of whom indicated that they were potentially interested in a strategic transaction with the Company, but were not in a position to do so at that time. Accordingly, neither Company C nor Company D expressed interest in conducting due diligence to pursue a transaction.

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On April 30, 2018, the Board convened a telephonic meeting with members of the Company’s senior management and representatives of Jones Day, Goldman Sachs and J.P. Morgan present. At the meeting, Ms. Scanlon informed the Board that Company A had communicated that it was unable to pursue a transaction with the Company at that time and that no other third party had emerged with a proposal to acquire the Company following the March 26th public filing by Knauf of its proposal to acquire the Company for $42.00 per share in cash. Ms. Scanlon also noted that both Institutional Shareholder Services and Glass Lewis, leading proxy advisory firms, had publicly announced their support for the vote against campaign and thus the Company was facing the likelihood of a majority vote against its four director nominees. Ms. Scanlon also informed the Board that Knauf’s general counsel, Mr. Schanow, had contacted the Company’s general counsel, Ms. Warner, to request a meeting and that Ms. Warner and Mr. Schanow were scheduled to meet later that day.

During the April 30th Board meeting, Ms. Scanlon also explained that, in light of feedback from a significant number of the Company’s stockholders that had urged the Company to engage with Knauf to try to find more value, the Company’s senior management had continued to evaluate its options with the Company’s advisors and recommended that the Company agree to sign a confidentiality agreement and share confidential information with Knauf to determine whether Knauf would improve its proposal. Discussions then turned to the terms of a confidentiality agreement, including with respect to a standstill provision. The Board then discussed with the Company’s senior management and the Company’s advisors the ways in which allowing Knauf to conduct due diligence might highlight the Company’s value. After considering the information presented by the Company’s senior management team and representatives of Jones Day, Goldman Sachs and J.P. Morgan, the Board determined to pursue the Company’s senior management’s proposed strategy of engagement with Knauf on the basis of confidential information, subject to any new information resulting from the meeting scheduled between Mr. Schanow and Ms. Warner. The Board also authorized Ms. Scanlon to begin negotiations on value within a range of $48.00 and $51.00 per share and discussed the pros and cons of issuing a public statement regarding the Board’s view of intrinsic value, but decided not to issue such a statement.

Later that day, Ms. Warner and Mr. Schanow met in-person. Mr. Schanow stated Knauf’s desire to have assurances regarding the final price that the Board would accept before making a further offer and reiterated Knauf’s willingness to sign a confidentiality agreement with the Company and receive additional information to support an increased offer. Mr. Schanow also stated Knauf’s view that the Company would want resolution prior to the annual meeting of stockholders scheduled for May 9, 2018, to avoid a vote against the Company’s four director nominees. He indicated that Knauf was prepared to move quickly, would provide a shortened due diligence request list and that Mr. Knauf and Mr. Grundke could be in Chicago as early as May 2, 2018. Ms. Warner stated that she was not authorized to negotiate price, but that she would report on the conversation with Mr. Schanow.

On May 1, 2018, Ms. Scanlon spoke with Mr. Knauf to discuss next steps with respect to a possible transaction and due diligence process, and the Company’s financial advisors held a telephonic meeting with Knauf’s financial advisors to discuss the process for due diligence and related matters. On the same day, the Company issued a press release announcing the Board’s authorization for senior management to begin negotiations with Knauf regarding a potential transaction, and the Company and Knauf began negotiating the terms of the confidentiality agreement. Ms. Scanlon also called Mr. Buffett later that same day to discuss the public announcement of the commencement of negotiations with Knauf.

On May 2, 2018, Ms. Scanlon and Mr. Hilzinger held an in-person meeting with Mr. Knauf and Mr. Grundke to discuss next steps and the terms of the confidentiality agreement, and agreed to meet again in person the following day to discuss a schedule for Knauf’s due diligence review of the Company’s non-public information and a timeline for a possible transaction. During the meeting, Mr. Knauf indicated that Knauf intended to spend several weeks conducting due diligence on the Company’s business before providing a revised proposal. The parties also discussed deal certainty issues and transaction process matters.

On May 3, 2018, Ms. Scanlon, Mr. Hilzinger, Ms. Warner and other members of the Company’s senior management met in-person with Mr. Knauf, Mr. Grundke and Mr. Schanow to further discuss process and timing

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for negotiating terms of a transaction agreement and Knauf’s due diligence review. On the same day, Knauf and the Company continued to negotiate terms of the confidentiality agreement. Jones Day and Baker McKenzie also discussed the terms of the confidentiality agreement, in particular the length and scope of the proposed standstill.

Later in the day on May 3, 2018, the Board held a telephonic meeting with members of the Company’s senior management and representatives of Jones Day, Goldman Sachs and J.P. Morgan to discuss the current status of negotiations with Knauf, including the discussions related to the terms of the confidentiality agreement. After considering the information presented by the Company’s senior management and representatives of Jones Day, Goldman Sachs and J.P. Morgan, the Board authorized the Company’s senior management to continue to negotiate the terms of the confidentiality agreement and continue discussions with Knauf, including a written counterproposal.

On May 4, 2018, the Company and Knauf entered into the confidentiality agreement to facilitate further discussions regarding a possible transaction.

On May 8, 2018, members of the Company’s senior management and representatives of Jones Day, Goldman Sachs and J.P. Morgan met with members of Knauf’s management and representatives from Baker McKenzie and Morgan Stanley to provide a management presentation and to continue discussions regarding due diligence matters and transaction terms. As authorized by the Board, following the due diligence meeting on May 8, 2018, Ms. Scanlon, Mr. Hilzinger and Ms. Warner met with Mr. Knauf, Mr. Grundke and Mr. Schanow to communicate a counterproposal of $50.00 per share. Ms. Scanlon stated that the Company would be willing to engage in further discussions and provide access to due diligence information to enable Knauf and the Company to reach a mutually agreeable transaction. This counterproposal was also provided in a written letter to Knauf.

On May 9, 2018, the Company held its annual meeting of stockholders. At the annual meeting, approximately 75% of shares voted were cast against each of the Company’s director nominees.

Between May 8, 2018 and May 11, 2018, representatives of the Company’s senior management and the Company’s financial advisors continued discussions regarding Knauf’s due diligence review, transaction terms and valuation. During this period, Mr. Leer participated in calls with the Company’s senior management and the Company’s legal and financial advisors to discuss the ongoing process and the best approach to maximizing value from Knauf.

On May 11, 2018, Baker McKenzie delivered a proposed draft merger agreement and draft voting agreement to Jones Day.

On May 18, 2018, Jones Day communicated by telephone with Baker McKenzie to discuss the draft merger agreement and key issues, including with respect to deal certainty, transaction structure and termination fees.

Also on May 18, 2018, members of the Company’s senior management, as well as representatives from Jones Day, Goldman Sachs and J.P. Morgan provided an update to the Board on the status of due diligence, negotiation of the merger agreement and next steps. Ms. Scanlon also provided an update on the second fiscal quarter of 2018.

On May 22, 2018, Ms. Warner, Mr. Schanow, and representatives from Jones Day and Baker McKenzie held in-person meetings in Chicago to negotiate terms of the merger agreement. The following day, Ms. Scanlon and Mr. Leer met in-person with Mr. Knauf and Mr. Grundke to discuss a revised price proposal from Knauf. During this meeting, Mr. Knauf rejected the Company’s $50.00 per share counterproposal and indicated that, although he continued to believe that $42.00 per share was full and fair value for the Company, Knauf was willing to increase its proposed price per share to $43.50. Mr. Knauf also delivered the revised proposal in writing. The revised proposal indicated Knauf’s view that the Company’s business plan did not adequately reflect the challenges presented by the highly cyclical and commoditized building products industry, execution risk with

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respect to the Company’s growth initiatives, customer consolidation, potential cost inflation, growth assumptions relating to the Company’s ceilings business, risks to the Company’s paper sourcing strategy and the need for significant future capital investment.

Ms. Scanlon and Mr. Leer indicated that, based on the synergies that the Company believed Knauf would realize in connection with the transaction and the Company’s projections, they believed Knauf should be willing to increase its proposal in the range of $47.00 per share and that a transaction at that level may be one that the Board would be willing to support, but that Ms. Scanlon and Mr. Leer would present Knauf’s offer of $43.50 to the Board. The parties did not make further progress on the price discussions, but agreed to talk again on the afternoon of May 24, 2018 and to continue work on the draft merger agreement.

On May 24, 2018, the Board held a telephonic meeting with members of the Company’s senior management team and representatives of Jones Day, Goldman Sachs and J.P. Morgan to discuss the revised price proposed by Knauf, key open issues in the merger agreement, and strategic options. Jones Day presented a review of the Board’s fiduciary duties to the Company’s stockholders in connection with the sale of control of the Company. Jones Day also reviewed the key issues that remained open in the merger agreement, including with respect to matters relating to deal certainty, treatment of equity awards and Knauf’s insistence on a termination fee in the event that stockholder approval of the adoption of the merger agreement is not obtained. The participants discussed market practice and precedent transactions in this context. Representatives of Goldman Sachs and J.P. Morgan discussed financial analyses of the Company as well as considerations for the Company continuing as a standalone company. Goldman Sachs and J.P. Morgan also presented information regarding potential alternative bidders if the Company were to solicit proposals to acquire the Company, recognizing that the discussions with Knauf were already in the public domain and no third party, other than Company A, expressed any interest in making a proposal or even conducting due diligence.

In executive session during the May 24, 2018 meeting, the Board discussed the current tone of negotiations and the potential for movement on price by Knauf, as well as concerns regarding certain operations of the Company’s UBBP joint venture and potential risks to the Company’s long range plan given some headwinds in certain markets. The Board asked members of the Company’s senior management to quantify the potential impact of these risks to value, as well as any potential upside to the long range plan. The Board further discussed possible strategies for bridging the gap on price, the risks of Knauf walking away from negotiations and engaging in a hostile acquisition of the Company at $42.00 per share or lower or pursuing an alternative transaction with another U.S. wallboard competitor. After careful consideration of the information presented, the Board authorized the Company’s senior management to continue negotiations with Knauf and granted Ms. Scanlon and Mr. Leer the authority to negotiate a transaction at a value equal to or greater than $44.00. The Board also authorized the Company’s senior management and the Company’s financial advisors to contact other possible buyers, including Company A, to determine whether there was interest by other parties in making a proposal for an alternative transaction.

On May 24, 2018 representatives of Goldman Sachs, J.P. Morgan and Morgan Stanley spoke to discuss the Company’s counterproposal, with Morgan Stanley stating that $43.50 per share was close to the maximum price Knauf was willing to pay and that Knauf was unwilling to split the difference between $43.50 and $47.00 per share.

On May 25, 2018, at the direction of the Board, Ms. Scanlon and Mr. Leer met in-person again with Mr. Knauf and Mr. Grundke. Mr. Knauf continued to reiterate a price of $43.50 per share and Mr. Leer offered a counterproposal of $45.25 per share. The parties also discussed a possible conditional special dividend to be paid by the Company to its stockholders if stockholder approval of the adoption of the merger agreement was obtained in an effort to bridge the value gap between the parties’ respective price proposals. Mr. Knauf informed Ms. Scanlon and Mr. Leer that he was only authorized to offer $43.50 per share. Mr. Knauf indicated that he would need to take the Company’s proposal back to the Knauf family shareholders for discussion. Following the discussions with Mr. Knauf and Mr. Grundke, Ms. Scanlon and Mr. Leer provided an update to the Board and the

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Company’s financial and legal advisors, indicating that they were scheduled to speak again with Knauf on May 29, 2018 and that they were still expecting a markup of the merger agreement from Knauf that day. Representatives of J.P. Morgan and Goldman Sachs confirmed that they were reaching out to other potential bidders.

Between May 25, 2018 and May 29, 2018, representatives of Goldman Sachs and J.P. Morgan contacted Company A and four other potential bidders as directed by the Board. Mr. Leer also spoke with the President of one of the other potential bidders. Company A reaffirmed that it was not in a position at that time to engage in an acquisition of the Company, and each of the other potential bidders indicated that they were unable or unwilling to submit a competing bid for the Company.

On May 29, 2018, Mr. Leer and Ms. Scanlon spoke with Mr. Knauf and Mr. Grundke regarding the status of the open merger agreement terms and offer price. Mr. Knauf reaffirmed Knauf’s $43.50 per share proposal and that there were a number of open points in the merger agreement potentially impacting value that needed to be resolved in a manner satisfactory to Knauf. Mr. Knauf also noted the weakening of the Euro against the Dollar, increasing the cost of the transaction to Knauf. Mr. Knauf expressed significant concern about whether an agreement could be reached between the parties. Mr. Leer stated that the Board was still at $45.25, but he felt that they would consider $45.00. Mr. Knauf indicated that he did not see a bridge between $45.25 and $43.50, but that he would encourage the advisors to continue to work on the merger agreement and resolve the open issues that could impact value.

On May 31, 2018, Ms. Warner, Mr. Schanow, and representatives from Jones Day and Baker McKenzie held in-person meetings in Chicago to continue to negotiate terms of the merger agreement, including with respect to deal certainty matters. The parties spoke again, on June 4, 2018, to continue negotiations on remaining open issues in the merger agreement.

On June 5, 2018, Mr. Knauf delivered by email a revised written proposal, together with a markup of the merger agreement. In the email, Mr. Knauf communicated that this constituted Knauf’s “best and final offer.” The revised proposal indicated that the previous proposal of $43.50 per share had stretched the limit of Knauf’s authorization after several discussions with the Knauf family shareholders. The letter then indicated that, following further discussions with the family shareholders and in a final attempt to reach an agreement on the transaction, Knauf was willing to agree to a total consideration proposal of $44.00 per share, consisting of $43.50 per share in cash at closing of the merger plus $0.50 per share in a conditional special dividend that the Company would be permitted to pay upon obtaining stockholder approval of adoption of the merger agreement. The revised proposal also conceded many of the open merger agreement terms in favor of the Company’s position.

On June 6, the Board held a telephonic meeting with members of the Company’s senior management team and representatives of Jones Day, Goldman Sachs and J.P. Morgan. The Board discussed the material open items with respect to the transaction terms, including Knauf’s proposals with respect to the break-up fee amount, the payment to Knauf of a fee in the event of failure to obtain stockholder approval of the adoption of the merger agreement, and the parties’ obligations in respect of regulatory filings and approvals. At this meeting, senior management presented to the Board the risks and opportunities to the long range plan. As part of this discussion, senior management noted that the risks that could negatively impact value included housing starts stagnating and that Knauf could enter the U.S. market through the acquisition of a competitor with management noting that Knauf’s perseverance in the current instance lead them to believe this scenario had a high likelihood. Senior management further noted a potential reduction in the anticipated financial benefits derived from strategic initiatives, and reduced EBITDA from the UBBP joint venture. Senior management also noted that the opportunities that could positively impact the Company’s value included the benefits from pricing analytics, supply chain optimization and wallboard price increases. The Board discussed the likelihood of the identified risks and opportunities, and the resulting impact on the Company’s value. Based on the foregoing considerations, the Board determined that it was willing to accept Knauf’s total consideration proposal of $44.00 per share (consisting of $43.50 per share in cash at closing of the merger plus $0.50 per share in a conditional special

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dividend). After discussing with the Company’s senior management and its advisors, the Board also determined that it was willing to accept Knauf’s proposal on the break-up fee amount, but rejected Knauf’s proposals relating to the fee in the event of a failure to obtain stockholder approval of the adoption of the merger agreement and the treatment of regulatory filings and approvals. Between June 6, 2018 and June 10, 2018, representatives of the Company and Knauf and the parties’ respective legal counsel continued to negotiate final transaction terms, including with respect to deal certainty and regulatory process.

On June 7, 2018, Ms. Scanlon and Ms. Warner spoke with Mr. Buffett on a confidential basis to inform him that Knauf was proposing that Berkshire Hathaway sign a voting agreement supporting a transaction with the Company and that Knauf’s counsel would be in touch with Berkshire Hathaway’s counsel. Ms. Scanlon provided an update on the key terms. Mr. Buffett indicated that Berkshire Hathaway would be willing to sign a voting agreement once the Company indicated it was satisfied with the terms. Ms. Scanlon spoke further with Mr. Buffett and Mr. Combs on June 8 and June 9, 2018. Representatives from Baker McKenzie negotiated the terms of the voting agreement with Berkshire Hathaway’s counsel during this period.

On June 10, 2018, the Board held an in-person special board meeting, with members of the Company’s senior management and representatives of Jones Day, Goldman Sachs and J.P. Morgan present, to consider the approval of the merger agreement negotiated with Knauf. During the meeting, representatives of Jones Day provided an overview of the Board’s fiduciary duties to the Company’s stockholders, including the Board’s duties in connection with the sale of control of the Company. Representatives from Goldman Sachs and J.P. Morgan discussed their financial analyses of the total consideration proposal of $44.00 per share (including the closing consideration of $43.50 per share in cash and the conditional special dividend of $0.50 per share) and each of Goldman Sachs and J.P. Morgan rendered their respective oral opinions to the Board, subsequently confirmed in writing, that as of June 10, 2018 and subject to the various limitations, assumptions, factors and matters set forth in the written opinion, the total consideration to be paid to the Company’s stockholders was fair, from a financial point of view, to such stockholders. Representatives of Goldman Sachs and J.P. Morgan indicated that their discussions with representatives of Company A and other possible bidders had all resulted in the companies confirming their inability to pursue or their lack of interest in pursuing a transaction with the Company. Representatives of Jones Day then led the Board in a discussion of the current terms and conditions of the merger agreement. After due consideration and discussion, the Board unanimously (i) determined that the merger agreement, the merger and the other transactions contemplated by the merger agreement are fair to, advisable and in the best interests of the Company and its stockholders, (ii) approved and declared advisable the merger agreement and the completion by the Company of the transactions contemplated thereby, including the execution, performance and delivery of the merger agreement, (iii) subject to the merger agreement, resolved to recommend the adoption of the merger agreement and the transactions contemplated thereby by the Company’s stockholders, and (iv) directed that the merger agreement be submitted to the Company’s stockholders for adoption.

Following the Board’s approval of the merger agreement and the merger, on the evening of June 10, 2018, the Company, Knauf and Merger Sub executed the merger agreement and Berkshire Hathaway, Knauf and Merger Sub signed the voting agreement. On the morning of June 11, 2018, the Company and Knauf issued a joint press release announcing entry into the merger agreement.

Recommendations of the Board and Reasons for the Merger

After due consideration and discussion, the Board unanimously (i) determined that the merger agreement, the merger and the other transactions contemplated by the merger agreement are fair to, advisable and in the best interests of the Company and its stockholders, (ii) approved and declared advisable the merger agreement and the completion by the Company of the transactions contemplated thereby, including the execution, performance and delivery of the merger agreement, (iii) subject to the terms of the merger agreement, resolved to recommend the adoption of the merger agreement and the transactions contemplated thereby by the Company’s stockholders, and (iv) directed that the merger agreement be submitted to the Company’s stockholders for adoption. The Board unanimously recommends you vote “FOR” adoption of the merger agreement.

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In making its determination, the Board considered a variety of factors and consulted with the Company’s senior management and outside legal and financial advisors. The discussion in this section is not intended to be an exhaustive list of the information and factors considered by the Board, although it does include material factors considered by the Board. In view of the wide variety of factors considered in connection with the merger, the Board did not consider it practicable to, nor did it attempt to, quantify or otherwise assign relative weights to the specific material factors it considered in reaching its decision. In addition, individual members of the Board may have given different weight to different factors. The Board considered this information and these factors based on the totality of the information and factors presented in deciding to recommend the adoption of the merger agreement.

The Board considered the following positive factors relating to the merger agreement and the merger (in no particular order of weight or relative importance, but each of which the Board believes supported its decision):

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The Board considered the following potentially negative factors relating to the merger agreement and the merger (in no particular order of weight or relative importance):

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This summary is not meant to be an exhaustive description of the information and factors considered by the Board, but is intended to address the most material information and factors considered by the Board. In view of the variety of factors considered by the Board, it is not possible to quantify or to give relative weights to the various factors. After taking into consideration all of the factors set forth above, as well as other factors not specifically described above, the Board unanimously determined that the merger agreement, the merger and the other transactions contemplated by the merger agreement are fair to, advisable and in the best interests of the Company and its stockholders, approved and declared advisable the merger agreement and the completion by the Company of the transactions contemplated thereby, including the execution, performance and delivery of the merger agreement, and directed that the merger agreement be submitted to the Company’s stockholders for adoption. The Board unanimously recommends that you vote “FOR” adoption of the merger agreement.

Certain USG Unaudited Prospective Financial Information

In September 2017, as part of its ordinary course strategy review with the Board, the Company’s management prepared a set of non-public, unaudited financial forecasts with respect to the Company’s business, as a standalone company, for fiscal years 2018 through 2022, to inform management’s formalization of the Company’s long range plan. In connection with the ordinary course strategy review with the Board, the Company’s management updated these forecasts in January 2018 to reflect items such as the completion of the Company’s acquisition of Ceilings Plus in November 2017 and a change to the Company’s Performance Materials division (the updated forecasts, the “Company Projections”). The Board and, as described under the section entitled “Proposal 1: The Merger—Opinions of the Company’s Financial Advisors,” the Company’s financial advisors reviewed the Company Projections in connection with their respective consideration and evaluation of the merger. The Company Projections were also provided to Knauf during the course of its due diligence review of the Company.

The Company does not as a matter of course make public projections as to future performance due to, among other reasons, the inherent difficulty of accurately predicting financial performance for future periods and the uncertainty of underlying assumptions and estimates. We are including in this proxy statement a summary of the Company Projections, without giving effect to the merger, to give Company stockholders access to certain non-public information provided to the Board, the Company’s financial advisors and Knauf for purposes of considering and evaluating the merger. This unaudited prospective financial information differs from the information presented at the Company’s Investor Day, which the Company believes was more conservative than the Company Projections. The inclusion of the summary of the Company Projections should not be regarded as an indication that the Company, Knauf, Merger Sub or any of their respective boards of directors or representatives or any other recipient of this information considered, or now considers, it to be an assurance of the achievement of future results or an accurate prediction of future results, and the summary of the Company Projections should not be relied on as such.

The Company Projections are based on a variety of estimates and assumptions of our senior management regarding our business, industry performance, cyclicality of the industry, general business, economic, market and financial conditions and other matters, all of which are difficult to predict and many of which are beyond our control. In particular, the Company Projections were prepared on the assumption that the Company remained a standalone company and were based on numerous other assumptions that may now be outdated. Multiple factors,

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including those described in the section entitled “Cautionary Statement Concerning Forward-Looking Statements,” could cause the Company Projections or the underlying assumptions to be inaccurate. As a result, there can be no assurance that the Company Projections will be realized or that actual results will not be significantly higher or lower than projected. Because the Company Projections cover multiple years, such information by its nature becomes less reliable with each successive year. The Company Projections do not take into account any circumstances or events occurring after the date on which they were prepared. Economic and business environments can and do change quickly, which adds an additional significant level of uncertainty as to whether the results portrayed in the Company Projections will be achieved. The inclusion of a summary of the Company Projections in this proxy statement does not constitute an admission or representation by the Company or any other person that the information is material. The summary of the Company Projections is not provided to influence Company stockholders’ decisions regarding whether to vote for adoption of the merger agreement or any other proposal.

The Company Projections were not prepared with a view toward public disclosure or toward compliance with U.S. generally accepted accounting principles (“U.S. GAAP”), published guidelines of the SEC or the guidelines established by the American Institute of Certified Public Accountants for preparation and presentation of prospective financial information. Neither Deloitte & Touche LLP (“Deloitte”), the Company’s independent registered public accounting firm, nor any other accounting firm, has examined, compiled or performed any procedures with respect to the Company Projections, and accordingly, Deloitte does not express an opinion or any other form of assurance with respect thereto. The Deloitte report incorporated by reference in this proxy statement relates to the Company’s historical financial information. It does not extend to the prospective financial information contained herein and should not be read to do so.

The Company Projections include “non-GAAP financial measures,” which should not be viewed as a substitute for, or superior to, U.S. GAAP financial measures and may be different from non-GAAP financial measures used by other companies. Furthermore, there are limitations inherent in non-GAAP financial measures because they exclude items, including charges and credits, that are required to be included in a U.S. GAAP presentation.

The following is a summary of the Company Projections:

Summary of the Company Projections

(dollars in millions)

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The Company Projections do not take into account the possible financial and other effects on the Company of the merger and do not attempt to predict or suggest future results of the combined company. The Company Projections do not give effect to the merger, including the impact of negotiating or executing the merger agreement, the expenses that may be incurred in connection with completing the merger, whether any synergies are achieved by the combined company as a result of the merger, the effect on the Company of any business or strategic decision or action that has been or will be taken as a result of the merger agreement having been executed, or the effect of any business or strategic decisions or actions that would likely have been taken if the merger agreement had not been executed, but that were instead altered, accelerated, postponed or not taken in anticipation of the merger. Further, the Company Projections do not take into account the effect on the Company of any possible failure of the merger to occur.

For the foregoing reasons as well as the uncertainties inherent in any forecasting information, readers of this proxy statement are cautioned not to place unwarranted reliance on the Company Projections set forth above. No one has made or makes any representation to any stockholder regarding the information included in the Company Projections. The Company urges all Company stockholders to review its most recent SEC filings for a description of its reported financial results. See the section entitled “Where You Can Find Additional Information.”

In addition, the Company Projections have not been updated or revised to reflect information or results after the date the Company Projections were prepared or as of the date of this proxy statement, or to reflect financial results or targets issued by the Company after the date the Company Projections were prepared, and except as required by applicable securities laws, the Company does not intend to update or otherwise revise the Company Projections or the specific portions presented to reflect circumstances existing after the date when made or to reflect the occurrence of future events, even in the event that any or all of the assumptions are shown to be in error. The Company Projections have also not been updated or revised to reflect illustrative risks and opportunities that have been considered, including risks such as a reduced macroeconomic environment in the United States, Asia, and Australia, new market entrants, or reduced benefits from strategic initiatives and opportunities such as pricing analytics, wallboard price improvements and reduced supply chain costs.

Opinions of the Company’s Financial Advisors

We retained Goldman Sachs and J.P. Morgan as financial advisors to the Board in connection with the merger. In connection with this engagement, the Board requested that Goldman Sachs and J.P. Morgan deliver the respective opinions described below.

Opinion of Goldman Sachs & Co. LLC

Pursuant to an engagement letter dated March 16, 2018, the Company retained Goldman Sachs as its financial advisor in connection with the transaction.

Goldman Sachs rendered its opinion to the Board that, as of June 10, 2018 and based upon and subject to the factors and assumptions set forth therein, the total consideration to be paid to the holders (other than Knauf and its affiliates) of shares of common stock pursuant to the merger agreement was fair from a financial point of view to such holders.

The full text of the written opinion of Goldman Sachs, dated June 10, 2018, which sets forth assumptions made, procedures followed, matters considered and limitations on the review undertaken in connection with the opinion, is attached as Annex B. Goldman Sachs provided advisory services and its opinion for the information and assistance of the Board in connection with its consideration of the transaction. The Goldman Sachs opinion is not a recommendation as to how any holder of common stock should vote with respect to the transaction, or any other matter.

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In connection with rendering the opinion described above and performing its related financial analyses, Goldman Sachs reviewed, among other things:

Goldman Sachs also held discussions with members of the senior management of the Company regarding their assessment of the past and current business operations, financial condition and future prospects of the Company; reviewed the reported price and trading activity for the common stock; compared certain financial and stock market information for the Company with similar information for certain other companies the securities of which are publicly traded; reviewed the financial terms of certain recent business combinations in the building products industry and in other industries; and performed such other studies and analyses, and considered such other factors, as it deemed appropriate.

For purposes of rendering this opinion, Goldman Sachs, with the Company’s consent, relied upon and assumed the accuracy and completeness of all of the financial, legal, regulatory, tax, accounting and other information provided to, discussed with or reviewed by, it, without assuming any responsibility for independent verification thereof. In that regard, Goldman Sachs assumed with the Company’s consent that the Forecasts were reasonably prepared on a basis reflecting the best currently available estimates and judgments of the management of the Company. Goldman Sachs did not make an independent evaluation or appraisal of the assets and liabilities (including any contingent, derivative or other off-balance-sheet assets and liabilities) of the Company and it was not furnished with any such evaluation or appraisal. Goldman Sachs assumed that all governmental, regulatory or other consents and approvals necessary for the consummation of the transaction will be obtained without any adverse effect on the expected benefits of the transaction in any way meaningful to its analysis. Goldman Sachs has also assumed that following the receipt of the stockholder approval and prior to the effective time of the transaction, the Company will declare and pay the conditional special dividend to all the holders of shares of common stock as contemplated by the merger agreement and that the transaction will be consummated on the terms set forth in the merger agreement, without the waiver or modification of any term or condition the effect of which would be in any way meaningful to its analysis.

Goldman Sachs’ opinion does not address the underlying business decision of the Company to engage in the transaction or the relative merits of the transaction as compared to any strategic alternatives that may be available to the Company; nor does it address any legal, regulatory, tax or accounting matters. Goldman Sachs’ opinion addresses only the fairness from a financial point of view, as of the date of the opinion, of the total consideration to be paid to the holders (other than Knauf and its affiliates) of shares of common stock pursuant to the merger agreement. Goldman Sachs’ opinion does not express any view on, and does not address, any other term or aspect of the merger agreement or the transaction or any term or aspect of any other agreement or instrument contemplated by the merger agreement or entered into or amended in connection with the transaction, including, any allocation of the total consideration, the fairness of the transaction to, or any consideration received in connection therewith by, the holders of any other class of securities, creditors, or other constituencies of the Company; nor as to the fairness of the amount or nature of any compensation to be paid or payable to any of the

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officers, directors or employees of the Company or class of such persons in connection with the transaction, whether relative to the total consideration to be paid to the holders (other than Knauf and its affiliates) of shares of common stock pursuant to the merger agreement or otherwise. Goldman Sachs does not express any opinion as to the impact of the transaction on the solvency or viability of the Company or Knauf or the ability of the Company or Knauf to pay their respective obligations when they come due. Goldman Sachs’ opinion was necessarily based on economic, monetary market and other conditions, as in effect on, and the information made available to it as of the date of the opinion and Goldman Sachs assumed no responsibility for updating, revising or reaffirming its opinion based on circumstances, developments or events occurring after the date of its opinion. Goldman Sachs’ advisory services and its opinion were provided for the information and assistance of the Board in connection with its consideration of the transaction and its opinion does not constitute a recommendation as to how any holder of shares of common stock should vote with respect to such transaction or any other matter. Goldman Sachs’ opinion was approved by a fairness committee of Goldman Sachs.

The following is a summary of the material financial analyses delivered by Goldman Sachs to the Board in connection with rendering the opinion of Goldman Sachs described above. The following summary, however, does not purport to be a complete description of the financial analyses performed by Goldman Sachs, nor does the order of analyses described represent relative importance or weight given to those analyses by Goldman Sachs. Some of the summaries of the financial analyses include information presented in tabular format. The tables must be read together with the full text of each summary and are alone not a complete description of Goldman Sachs’ financial analyses. Except as otherwise noted, the following quantitative information, to the extent that it is based on market data, is based on market data as it existed on or before June 8, 2018, the last trading day before the public announcement of the transaction, and is not necessarily indicative of current market conditions.

Historical Stock Trading Analysis. Goldman Sachs reviewed the historical trading prices and volumes for the shares of common stock for the 52-week period ended March 23, 2018, the last trading day prior to Knauf’s and Berkshire Hathaway’s Schedule 13Ds related to Berkshire Hathaway’s proposal to grant Knauf an option to purchase all of the shares of the Company’s common stock (the “last undisturbed trading day”). In addition, Goldman Sachs analyzed the total consideration to be paid to holders of common stock pursuant to the merger agreement in relation to (i) the closing prices of common stock on June 8, 2018, the last trading day prior to public announcement of the transaction, and March 23, 2018, the last undisturbed trading day, (ii) the high closing price of common stock for the 52-week period ended on the last undisturbed trading day, (iii) the volume weighted average prices (the “VWAP”) of common stock during the one-month and three-month periods ended on the last undisturbed trading day and (iv) the median analyst price target as of the last undisturbed trading day.

This analysis indicated that the total consideration to be paid to the Company stockholders pursuant to the merger agreement represented:

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Selected Companies Analysis. Goldman Sachs reviewed and compared certain financial information for the Company to corresponding financial information, ratios and public market multiples for the following publicly-traded corporations in the building products industry (collectively referred to in this analysis as the “selected companies”):

Although none of the selected companies is directly comparable to the Company, the companies included were chosen because they are publicly-traded companies with operations that for purposes of analysis may be considered similar to certain operations of the Company.

Goldman Sachs calculated enterprise value as a multiple of estimated EBITDA (defined as earnings before interest, taxes, depreciation and amortization) calendarized to year end 2018 and 2019 for the selected companies based on information contained in the selected companies’ public filings and obtained from Bloomberg and Institutional Brokers’ Estimate System (“IBES”) estimates. The multiples of the selected companies were calculated using closing prices on June 8, 2018 and were calculated using IBES estimates. The following table presents the results of this analysis:

Illustrative Discounted Cash Flow Analysis. Using the Forecasts, Goldman Sachs performed an illustrative discounted cash flow analysis to derive a range of illustrative present values per share of common stock. In connection with this analysis, Goldman Sachs performed separate illustrative discounted cash flow analyses of: (i) the Company, excluding the Company’s ownership stake in the UBBP joint venture and excluding the value of USG’s net operating losses (“NOLs”) and other tax attributes (“USG NA”), (ii) the Company’s ownership interest in the UBBP joint venture and (iii) the estimated benefits of the Company’s NOLs and other tax attributes discounted to present value.

Using discount rates ranging from 9.5% to 10.5%, reflecting estimates of the weighted average cost of capital for the Company, Goldman Sachs discounted to present value as of March 31, 2018 (i) estimates of unlevered free cash flow for USG NA for April 1, 2018 through December 31, 2022 as reflected in the Forecasts and (ii) a range of illustrative terminal values for USG NA, which were calculated by applying perpetuity growth rates ranging from 2.0% to 3.0%, to a terminal year estimate of the unlevered free cash flow to be generated by USG NA as provided by the Company management. Goldman Sachs derived such discount rates by application of the Capital Asset Pricing Model, which requires certain company-specific inputs, including the Company’s target capital structure weightings, the cost of long-term debt, after-tax yield on permanent excess cash, if any, future applicable marginal cash tax rate and a beta for the Company, as well as certain financial metrics for the United States financial markets generally. The range of perpetuity growth rates was estimated by Goldman Sachs utilizing its professional judgment and experience, taking into account the Forecasts and market expectations regarding long-term real growth of gross domestic product and inflation. Goldman Sachs derived a range of illustrative enterprise values for USG NA by adding the range of present values derived above. Goldman Sachs

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then subtracted from the range of illustrative enterprise values it derived for USG NA the amount of the Company’s net debt and after-tax underfunded pension and postretirement liabilities as of March 31, 2018 as provided by the Company management to derive a range of illustrative equity values for USG NA.

Using discount rates ranging from 10.0% to 11.0%, reflecting estimates of the weighted average cost of capital for the UBBP joint venture, Goldman Sachs discounted to present value as of March 31, 2018 (i) estimates of unlevered free cash flow for the UBBP joint venture for April 1, 2018 through December 31, 2022 as provided by the Company management and (ii) a range of illustrative terminal values for the UBBP joint venture, which were calculated by applying perpetuity growth rates ranging from 3.0% to 4.0%, to a terminal year estimate of the unlevered free cash flow to be generated by the UBBP joint venture, as provided by the Company management. Goldman Sachs derived such discount rates by application of the methodologies described above and applying a country risk premium. The range of perpetuity growth rates was estimated by Goldman Sachs utilizing its professional judgment and experience, taking into account the Forecasts and market expectations regarding long-term real growth of gross domestic product and inflation. Goldman Sachs derived a range of illustrative enterprise values for the UBBP joint venture by adding the range of present values derived above. Goldman Sachs then subtracted from the range of illustrative enterprise values it derived for the UBBP joint venture the amount of the UBBP joint venture’s net debt as of March 31, 2018 as provided by the Company management to derive a range of illustrative equity values for the UBBP joint venture. Goldman Sachs then multiplied the range of illustrative equity values for the UBBP joint venture by 0.50 to derive a range of illustrative equity values for the Company’s ownership stake in the UBBP joint venture.

In addition, using discount rates ranging from 9.5% to 10.5%, reflecting estimates of the weighted average cost of capital for the Company, Goldman Sachs discounted to present value as of March 31, 2018 the estimated benefits of the Company’s NOLs and other tax attributes for April 1, 2018 through December 31, 2032 as provided by the Company management. Goldman Sachs noted that the range of illustrative aggregate enterprise values for USG NA, the Company’s ownership stake in the UBBP joint venture and the Company’s NOLs and other tax attributes implied a range of terminal enterprise value/EBITDA multiples of 7.5x to 9.9x. Goldman Sachs added the range of illustrative equity values for USG NA, for the Company’s ownership stake in the UBBP joint venture and for the Company’s NOLs and other tax attributes to derive a range of illustrative aggregate equity values for the Company. Goldman Sachs then divided the range of illustrative equity values it derived by the number of fully diluted outstanding shares of the Company, as provided by the Company management, to derive a range of illustrative present values per share ranging from $41 to $53, in each case rounded to the nearest dollar.

Selected Transactions Analysis. Goldman Sachs analyzed certain information relating to the following selected all-cash transactions in the building products industry. For each of the selected transactions, Goldman Sachs calculated and compared the estimated transaction enterprise value as a multiple of the target company’s EBITDA as reported or calculated using publicly available financial information for the relevant twelve-month period (“EV/LTM EBITDA multiples”) of the applicable transaction.

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While none of the companies that participated in the selected transactions are directly comparable to the Company, the companies that participated in the selected transactions are companies with operations that, for the purposes of analysis, may be considered similar to certain of the Company’s results, market size and product profile. The following table presents the results of this analysis:

Goldman Sachs applied an illustrative range of EV/LTM EBITDA multiples of 9.0x to 11.5x to estimated EBITDA of the Company for the twelve-month period ended March 31, 2018 as provided by the Company management to derive a range of illustrative implied values of $33 to $44 per share of common stock, in each case rounded to the nearest dollar.

Premia Analysis. Goldman Sachs reviewed and analyzed, using publicly available information, the acquisition premia for all-cash acquisition transactions announced from January 2013 through June 8, 2018 involving a U.S. public company target where the disclosed enterprise value for the transaction was between $4 billion and $10 billion. This analysis excluded transactions in the financial institutions and real estate sectors, transactions where the target was a master limited partnership and withdrawn transactions. For the entire period, using publicly available information, Goldman Sachs calculated the premium of the per share price paid in each of the transactions relative to the target’s undisturbed closing stock price. This analysis indicated a range of illustrative premia of 25% to 44%. Goldman Sachs then applied the reference range of illustrative premia to the closing price per share of common stock of $33.51 on the last undisturbed trading day and calculated a range of implied equity values per share of common stock of $42 to $48, in each case rounded to the nearest dollar.

The preparation of a fairness opinion is a complex process and is not necessarily susceptible to partial analysis or summary description. Selecting portions of the analyses or of the summary set forth above, without considering the analyses as a whole, could create an incomplete view of the processes underlying Goldman Sachs’ opinion. In arriving at its fairness determination, Goldman Sachs considered the results of all of its analyses and did not attribute any particular weight to any factor or analysis considered by it. Rather, Goldman Sachs made its determination as to fairness on the basis of its experience and professional judgment after considering the results of all of its analyses. No company or transaction used in the above analyses as a comparison is directly comparable to the Company or the contemplated transaction.

Goldman Sachs prepared these analyses for purposes of Goldman Sachs’ providing its opinion to the Board as to the fairness from a financial point of view of the total consideration to be paid to the holders (other than Knauf and its affiliates) of shares of common stock pursuant to the merger agreement. These analyses do not purport to be appraisals nor do they necessarily reflect the prices at which businesses or securities actually may be sold. Analyses based upon forecasts of future results are not necessarily indicative of actual future results, which may be significantly more or less favorable than suggested by these analyses. Because these analyses are inherently subject to uncertainty, being based upon numerous factors or events beyond the control of the parties or their respective advisors, none of the Company, Knauf, Goldman Sachs or any other person assumes responsibility if future results are materially different from those forecast.

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The total consideration was determined through arm’s-length negotiations between the Company and Knauf and was approved by the Board. Goldman Sachs provided advice to the Company during these negotiations. Goldman Sachs did not, however, recommend any specific amount of consideration to the Company or the Board or that any specific amount of consideration constituted the only appropriate consideration for the transaction.

As described above, Goldman Sachs’ opinion to the Board was one of many factors taken into consideration by the Board in making its determination to approve the merger agreement. The foregoing summary does not purport to be a complete description of the analyses performed by Goldman Sachs in connection with the fairness opinion and is qualified in its entirety by reference to the written opinion of Goldman Sachs attached as Annex B.

Goldman Sachs and its affiliates are engaged in advisory, underwriting and financing, principal investing, sales and trading, research, investment management and other financial and non-financial activities and services for various persons and entities. Goldman Sachs and its affiliates and employees, and funds or other entities in which they invest or with which they co-invest, may at any time purchase, sell, hold or vote long or short positions and investments in securities, derivatives, loans, commodities, currencies, credit default swaps and other financial instruments of the Company, Knauf, any of their respective affiliates and third parties, including Berkshire Hathaway, a significant shareholder of the Company, or any currency or commodity that may be involved in the transaction contemplated by the merger agreement for the accounts of Goldman Sachs and its affiliates and employees and their customers. Goldman Sachs acted as financial advisor to the Company in connection with, and participated in certain of the negotiations leading to, the transaction contemplated by the merger agreement. Goldman Sachs has provided certain financial advisory and/or underwriting services to the Company and/or its affiliates from time to time for which the Investment Banking Division of Goldman Sachs has received, and may receive, compensation, including having acted as financial advisor to the Company in connection with the sale of L&W Supply Corporation, a former subsidiary of the Company, in October 2016 and joint bookrunner with respect to 4.875% senior notes due 2027 (aggregate principal amount of $500,000,000) for the Company in May 2017. During the two year period ended June 10, 2018, Goldman Sachs has recognized compensation for financial advisory and/or underwriting services provided by its Investment Banking Division to the Company and/or its affiliates of approximately $2.7 million. During the two year period ended June 10, 2018, the Investment Banking Division of Goldman Sachs has not been engaged by Knauf or its affiliates to provide financial advisory or underwriting services for which Goldman Sachs has received compensation. Goldman Sachs has provided certain financial advisory and/or underwriting services to Berkshire Hathaway and/or its affiliates and portfolio companies from time to time for which the Investment Banking Division of Goldman Sachs has received, and may receive, compensation, including having acted as joint bookrunner with respect to 1.150% senior notes due 2018 (aggregate principal amount $500,000,000), floating rate senior notes due 2018 (aggregate principal amount $250,000,000), 1.300% guaranteed senior notes due 2019 (aggregate principal amount $1,000,000,000) and floating rate guaranteed senior notes due 2019 (aggregate principal amount $250,000,000) for Berkshire Hathaway in August 2016; joint bookrunner with respect to floating rate guaranteed senior notes due 2019 and 2020 (aggregate principal amount $1,300,000,000), 0.250% senior notes due 2021 and 0.625% senior notes due 2023 (aggregate principal amount EUR1,100,000,000) for Berkshire Hathaway in January 2017; joint bookrunner with respect to 3.250% senior unsecured debentures due 2027 and 4.125% senior unsecured debentures due 2047 (aggregate principal amount $1,250,000,000) for Burlington Northern Santa Fe Corporation, a portfolio company of Berkshire Hathaway, in March 2017; joint bookrunner with respect to floating rate guaranteed senior notes due 2022, 2021 and 2019 (aggregate principal amount $1,500,000,000) for the Kraft Heinz Food Company, a portfolio company of Berkshire Hathaway, in August 2017; joint bookrunner with respect to 4.050% senior unsecured debentures due 2048 (aggregate principal amount $750,000,000) for Burlington Northern Santa Fe Corporation in February 2018; dealer with respect to a guaranteed commercial paper program for NetJets Inc., a portfolio company of Berkshire Hathaway, until March 2018; and joint bookrunner with respect to 3.375% senior notes due 2021, 4.000% senior notes due 2023, and 4.625% senior notes due 2029 (aggregate principal amount $3,000,000,000) for the Kraft Heinz Food Company in June 2018. During the two year period ended June 10, 2018, Goldman Sachs has recognized compensation for financial advisory and/or underwriting services provided by its Investment Banking Division to Berkshire Hathaway and/or its affiliates and portfolio companies of approximately $5.8 million. Goldman Sachs may also in the future

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provide financial advisory and/or underwriting services to the Company, Knauf, Berkshire Hathaway and their respective affiliates and/or portfolio companies for which Goldman Sachs’ Investment Banking Division may receive compensation. Goldman Sachs and its affiliates also may have co-invested with Berkshire Hathaway and its affiliates from time to time and may do so in the future.

The Board selected Goldman Sachs as its financial advisor because it is an internationally recognized investment banking firm that has substantial experience in transactions similar to the transaction. Pursuant to a letter agreement dated March 16, 2018, the Company engaged Goldman Sachs to act as its financial advisor in connection with the transaction. The engagement letter between the Company and Goldman Sachs provides for a transaction fee that is estimated, based on the information available as of the date of announcement, to be approximately $31 million, of which $125,000 has been paid as of August 23, 2018, and the principal portion of which is contingent upon consummation of the transaction. In addition, the Company has agreed to reimburse Goldman Sachs for certain of its expenses, including attorneys’ fees and disbursements, and to indemnify Goldman Sachs and related persons against various liabilities, including certain liabilities under the federal securities laws.

Opinion of J.P. Morgan Securities LLC

Pursuant to an engagement letter dated February 14, 2018, the Company retained J.P. Morgan as its financial advisor in connection with the transaction.

At the meeting of the Board on June 10, 2018, J.P. Morgan rendered its oral opinion to the Board that, as of such date and based upon and subject to the factors and assumptions set forth in its opinion, the total consideration to be paid to the holders of shares of common stock in the transaction was fair, from a financial point of view, to such holders. J.P. Morgan has confirmed its June 10, 2018 oral opinion by delivering its written opinion to the Board, dated the date of such opinion, that, as of such date, the total consideration to be paid to the holders of shares of common stock in the transaction was fair, from a financial point of view, to such holders.

The full text of the written opinion of J.P. Morgan dated June 10, 2018, which sets forth the assumptions made, matters considered and limits on the review undertaken, is attached as Annex C to this proxy statement and is incorporated herein by reference. The summary of the opinion of J.P. Morgan set forth in this proxy statement is qualified in its entirety by reference to the full text of such opinion. The Company’s stockholders are urged to read the opinion in its entirety. J.P. Morgan’s written opinion was addressed to the Board (in its capacity as such) in connection with and for the purposes of its evaluation of the transaction, was directed only to the total consideration to be paid in the transaction and did not address any other aspect of the transaction. J.P. Morgan expressed no opinion as to the fairness of the consideration to the holders of any class of securities, creditors or other constituencies of the Company or as to the underlying decision by the Company to engage in the transaction. The issuance of J.P. Morgan’s opinion was approved by a fairness committee of J.P. Morgan. The opinion does not constitute a recommendation to any stockholder of the Company as to how such stockholder should vote with respect to the transaction or any other matter.

In arriving at its opinion, J.P. Morgan, among other things:

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In addition, J.P. Morgan held discussions with certain members of the management of the Company with respect to certain aspects of the transaction, and the past and current business operations of the Company, the financial condition and future prospects and operations of the Company, and certain other matters J.P. Morgan believed necessary or appropriate to its inquiry.

In giving its opinion, J.P. Morgan relied upon and assumed the accuracy and completeness of all information that was publicly available or was furnished to or discussed with J.P. Morgan by the Company or otherwise reviewed by or for J.P. Morgan. J.P. Morgan did not independently verify any such information or its accuracy or completeness and, pursuant to J.P. Morgan’s engagement letter with the Company, J.P. Morgan did not assume any obligation to undertake any such independent verification. J.P. Morgan did not conduct or was not provided with any valuation or appraisal of any assets or liabilities, nor did J.P. Morgan evaluate the solvency of the Company or Knauf under any applicable laws relating to bankruptcy, insolvency or similar matters. In relying on financial analyses and forecasts provided to J.P. Morgan or derived therefrom, J.P. Morgan assumed that they were reasonably prepared based on assumptions reflecting the best currently available estimates and judgments by management as to the expected future results of operations and financial condition of the Company to which such analyses or forecasts relate. J.P. Morgan expressed no view as to such analyses or forecasts or the assumptions on which they were based. J.P. Morgan also assumed that immediately following the receipt of the stockholder approval and prior to the effective time of the transaction, the Company will declare and pay the conditional special dividend to all the holders of shares of common stock as contemplated by the merger agreement and that the transaction and the other transactions contemplated by the merger agreement will be consummated as described in the merger agreement, and that the definitive merger agreement would not differ in any material respect from the draft thereof provided to J.P. Morgan. J.P. Morgan also assumed that the representations and warranties made by the Company, Knauf and Merger Sub in the merger agreement and the related agreements were and will be true and correct in all respects material to its analysis. J.P. Morgan is not a legal, regulatory or tax expert and relied on the assessments made by advisors to the Company with respect to such issues. J.P. Morgan further assumed that all material governmental, regulatory or other consents and approvals necessary for the consummation of the transaction will be obtained without any adverse effect on the Company or on the contemplated benefits of the transaction.

J.P. Morgan’s opinion was necessarily based on economic, market and other conditions as in effect on, and the information made available to J.P. Morgan as of, the date of such opinion. J.P. Morgan’s opinion noted that subsequent developments may affect J.P. Morgan’s opinion, and that J.P. Morgan does not have any obligation to update, revise, or reaffirm such opinion. J.P. Morgan’s opinion is limited to the fairness, from a financial point of view, of the total consideration to be paid to the holders of shares of common stock in the transaction, and J.P. Morgan has expressed no opinion as to the fairness of any consideration to the holders of any other class of securities, creditors or other constituencies of the Company or the underlying decision by the Company to engage in the transaction. Furthermore, J.P. Morgan expressed no opinion with respect to the amount or nature of any compensation to any officers, directors, or employees of any party to the transaction, or any class of such persons relative to consideration to be paid to the holders of shares of common stock in the transaction or with respect to the fairness of any such compensation.

The terms of the merger agreement were determined through arm’s length negotiations between the Company and Knauf, and the decision to enter into the merger agreement was solely that of the Board. J.P. Morgan’s opinion and financial analyses were only one of the many factors considered by the Board in its

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evaluation of the transaction and should not be viewed as determinative of the views of the Board or management of the Company with respect to the transaction or the consideration to be paid in the transaction.

In accordance with customary investment banking practice, J.P. Morgan employed generally accepted valuation methodology in rendering its opinion to the Board on June 10, 2018 and contained in the presentation delivered to the Board on such date in connection with the rendering of such opinion and this summary does not purport to be a complete description of the analyses or data presented by J.P. Morgan. Some of the summaries of the financial analyses include information presented in tabular format. The tables are not intended to stand alone, and in order to more fully understand the financial analyses used by J.P. Morgan, the tables must be read together with the full text of each summary. Considering the data set forth below without considering the full narrative description of the financial analyses, including the methodologies and assumptions underlying the analyses, could create a misleading or incomplete view of J.P. Morgan’s analyses.

Public Trading Multiples.

Using publicly available information, J.P. Morgan compared selected financial data of the Company with similar data for selected publicly-traded companies engaged in businesses which J.P. Morgan judged to be analogous to the Company. The companies selected by J.P. Morgan were:

None of the selected companies reviewed is identical to the Company. Certain of these companies may have characteristics that are materially different from those of the Company. However, the companies were selected, among other reasons, because they are publicly-traded companies with operations and businesses that, for purposes of J.P. Morgan’s analysis, may be considered similar to those of the Company. The analyses necessarily involve complex considerations and judgments concerning differences in financial and operational characteristics of the companies involved and other factors that could affect the companies differently than they would affect the Company.

Using publicly available information from Bloomberg and IBES, J.P. Morgan calculated for each selected company, the ratio of such company’s firm value (calculated as the market value of the Company’s common stock on a fully diluted basis, plus any debt and minority interest, less cash and cash equivalents) to the equity research analyst estimate for such company’s EBITDA (defined as earnings before interest, taxes, depreciation and amortization) calendarized to year end 2018 (the “2018E EV/EBITDA”) and the ratio of such company’s firm value to the equity research analyst estimate for the company’s estimated EBITDA calendarized to year end 2019 (the “2019E EV/EBITDA”). The following table represents the results of this analysis:

Based on the results of this analysis and other factors which J.P. Morgan considered appropriate based on its experience and judgment, J.P. Morgan selected multiple reference ranges for the Company of 9.0x to 10.5x and 8.0x to 9.5x for 2018E EV/EBITDA and 2019E EV/EBITDA, respectively.

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After applying this range to the Company’s estimated EBITDA for the fiscal years ended December 31, 2018 and December 31, 2019 based on the Company Projections (as defined in the section entitled “—Certain USG Unaudited Prospective Financial Information”), the analysis indicated the following implied per share equity value ranges for the common stock:

The ranges of implied per share equity value were compared to (i) the closing price of the common stock on the last undisturbed trading day and (ii) the total consideration.

Discounted Cash Flow Analysis.

J.P. Morgan conducted a discounted cash flow analysis for the purpose of determining an implied equity value per share of the common stock. A discounted cash flow analysis is a method of evaluating an asset using estimates of the future cash flows generated by the asset and taking into consideration the time value of money with respect to those cash flows by calculating their “present value.” “Present value” refers to the current value of the cash flows generated by the asset, and is obtained by discounting those cash flows back to the present using a discount rate that takes into account macro-economic assumptions and estimates of risk, the opportunity cost of capital and other appropriate factors. “Terminal value” refers to the present value of all future cash flows generated by the asset for periods beyond the projections period.

J.P. Morgan calculated the unlevered free cash flows that USG NA is expected to generate for April 1, 2018 through December 31, 2022, using the Company Projections. J.P. Morgan also calculated a range of terminal values of the Company at the end of the five-year period ending 2022 by applying a terminal value growth rate ranging from 2.0% to 3.0% to the unlevered free cash flow of USG NA during the terminal period of the projections and then the unlevered free cash flows and the range of terminal values were then discounted to present values as of March 31, 2018 using a range of discount rates from 9.25% to 10.25%, which range was chosen by J.P. Morgan based upon an analysis of the weighted average cost of capital of the Company. J.P. Morgan derived a range of illustrative enterprise values for USG NA by adding the range of present values derived above. J.P. Morgan then subtracted from the range of illustrative enterprise values it derived for USG NA the amount of the Company’s net debt as of March 31, 2018 as provided by the Company management to derive a range of illustrative equity values for USG NA.

Using the Company Projections, J.P. Morgan separately calculated the unlevered free cash flows that the UBBP joint venture is expected to generate for April 1, 2018 through December 31, 2022. J.P. Morgan also calculated a range of terminal values of the UBBP joint venture at the end of the five-year period ending 2022 by applying a terminal value growth rate ranging from 3.0% to 4.0% to the unlevered free cash flow of the UBBP joint venture during the terminal period of the projections, and the unlevered free cash flows and the range of terminal values were then discounted to present values as of March 31, 2018 using a range of discount rates from 9.75% to 10.75%, which range was chosen by J.P. Morgan based upon an analysis of the weighted average cost of capital of the UBBP joint venture. J.P. Morgan derived range of illustrative enterprise values for the UBBP joint venture by adding the range of present values derived above. J.P. Morgan then subtracted from the range of illustrative enterprise values it derived for the UBBP joint venture the amount of the UBBP joint venture’s net debt as of March 31, 2018 as provided by the Company management to derive a range of illustrative equity values for the UBBP joint venture. J.P. Morgan then multiplied the range of illustrative equity values for the UBBP joint venture by 0.50 to derive a range of illustrative equity values for the Company’s ownership stake in the UBBP joint venture.

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Finally, using the Company Projections, J.P. Morgan discounted to present value as of March 31, 2018 the estimated benefits of the Company’s NOLs and other tax attributes, for April 1, 2018 through December 31, 2032, using a range of discount rates from 9.25% to 10.25%, which range was chosen by J.P. Morgan based upon an analysis of the weighted average cost of capital for the Company. J.P. Morgan then added the range of illustrative equity values for USG NA, the Company’s ownership stake in the UBBP joint venture and the Company’s NOLs and other tax credits to derive a range of illustrative aggregate equity values for the Company.

Based on the foregoing, this analysis indicated an implied per share equity value range for shares of common stock of $42.09 to $55.25 each of which was compared to (i) the closing price of the common stock on the last undisturbed trading day and (ii) the total consideration.

Selected Transactions Analysis.

Using publicly available information, J.P. Morgan reviewed selected transactions involving acquired business in the building products industry that, for purposes of J.P. Morgan’s analysis and based on its experience and judgment, were considered similar to the Company’s business and calculated, for each selected transaction, the ratio of the target company’s transaction value to the target company’s EBITDA as reported or calculated using publicly available financial information for the relevant twelve-month period of the applicable transaction (“TV/LTM EBITDA”).

None of the selected transactions reviewed was identical to the transaction. Certain of these transactions may have characteristics that are materially different from those of the transaction. However, the transactions selected were chosen because the participants in, and certain other aspects of, the transactions, for purposes of J.P. Morgan’s analysis, may be considered similar to the participants in and aspects of the transaction. The analyses necessarily involve complex considerations and judgments concerning differences in financial and operational characteristics of the companies involved and other factors that could affect the transactions differently than they would affect the transaction.

Based on the results of this analysis, J.P. Morgan selected a multiple reference range of 9.0x to 11.5x for TV/LTM EBITDA and applied it to the Company’s EBITDA for the twelve-month period ended March 31, 2018 as provided by the Company management. The analysis indicated an implied per share equity value range for shares of common stock of $33.00 to $43.75, in each case rounded to the nearest $0.25, which was compared to (i) the closing price of the common stock on the last undisturbed trading day and (ii) the total consideration.

Other Information.

Historical Trading Range. J.P. Morgan reviewed the 52-week trading range of the common stock for the period ending on the last undisturbed trading day, which was $25.78 to $40.82 per share, and compared that to (i) the closing price of the common stock on the last undisturbed trading day and (ii) the total consideration.

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Analysts Price Targets. J.P. Morgan reviewed the price targets of public equity research analysts for the Company, which provided a reference of $29.00 to $44.00 per share, with a median price target of $37.50 per share, as of March 23, 2018, and compared that to (i) the closing price of the common stock on the last undisturbed trading day and (ii) the total consideration.

J.P. Morgan noted that the historical stock trading range analyses and analyst price targets noted above were presented merely for reference purposes only and were not relied upon for valuation purposes.

Miscellaneous

The foregoing summary of certain material financial analyses does not purport to be a complete description of the analyses or data presented by J.P. Morgan. The preparation of a fairness opinion is a complex process and is not necessarily susceptible to partial analysis or summary description. J.P. Morgan believes that the foregoing summary and its analyses must be considered as a whole and that selecting portions of the foregoing summary and these analyses, without considering all of its analyses as a whole, could create an incomplete view of the processes underlying the analyses and its opinion. As a result, the ranges of valuations resulting from any particular analysis or combination of analyses described above were merely utilized to create points of reference for analytical purposes and should not be taken to be the view of J.P. Morgan with respect to the actual value of the Company. The order of analyses described does not represent the relative importance or weight given to those analyses by J.P. Morgan. In arriving at its opinion, J.P. Morgan did not attribute any particular weight to any analyses or factors considered by it and did not form an opinion as to whether any individual analysis or factor (positive or negative), considered in isolation, supported or failed to support its opinion. Rather, J.P. Morgan considered the totality of the factors and analyses performed in determining its opinion.

Analyses based upon forecasts of future results are inherently uncertain, as they are subject to numerous factors or events beyond the control of the parties and their advisors. Accordingly, forecasts and analyses used or made by J.P. Morgan are not necessarily indicative of actual future results, which may be significantly more or less favorable than suggested by those analyses. Moreover, J.P. Morgan’s analyses are not and do not purport to be appraisals or otherwise reflective of the prices at which businesses actually could be acquired or sold. None of the selected companies reviewed as described in the above summary is identical to the Company, and none of the selected transactions reviewed was identical to the transaction. However, the companies selected were chosen because they are publicly-traded companies with operations and businesses that, for purposes of J.P. Morgan’s analysis, may be considered similar to those of the Company. The transactions selected were similarly chosen because their participants, size and other factors, for purposes of J.P. Morgan’s analysis, may be considered similar to the transaction. The analyses necessarily involve complex considerations and judgments concerning differences in financial and operational characteristics of the companies involved and other factors that could affect the companies compared to the Company and the transactions compared to the transaction.

As a part of its investment banking business, J.P. Morgan and its affiliates are continually engaged in the valuation of businesses and their securities in connection with mergers and acquisitions, investments for passive and control purposes, negotiated underwritings, secondary distributions of listed and unlisted securities, private placements, and valuations for corporate and other purposes. J.P. Morgan was selected to advise the Company with respect to the transaction on the basis of, among other things, such experience and its qualifications and reputation in connection with such matters and its familiarity with the Company and the industries in which it operates.

J.P. Morgan received a fee from the Company of $3 million in connection with the delivery of its opinion. The Company has agreed to pay J.P. Morgan a transaction fee that is estimated, based on the information available as of the date of announcement, to be approximately $31 million, against which the opinion fee will be credited, upon the consummation of the transaction. In addition, the Company has agreed to reimburse J.P. Morgan for its expenses incurred in connection with its services, including the fees and disbursements of counsel, and will indemnify J.P. Morgan against certain liabilities arising out of J.P. Morgan’s engagement. During the

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two years preceding the date of J.P. Morgan’s opinion, J.P. Morgan and its affiliates have had commercial or investment banking relationships with the Company and Berkshire Hathaway, for which J.P. Morgan and such affiliates have received customary compensation. Such services during such period have included acting as joint lead arranger and joint bookrunner on the Company’s credit facility which closed in May 2017, joint lead bookrunner on the Company’s offering of debt securities which closed in May 2017 and financial advisor to the Company in connection with a sale transaction which closed in October 2016 and as joint lead bookrunner on Berkshire Hathaway’s offerings of debt securities which closed in January 2017 and August 2016. In addition, J.P. Morgan’s commercial banking affiliate is an agent bank and a lender under outstanding credit facilities of the Company, for which it receives customary compensation or other financial benefits. During the two year period preceding delivery of its opinion ending on June 10, 2018, the aggregate fees received by J.P. Morgan from the Company were approximately $10 million and from Berkshire Hathaway were approximately $30 million. Stephen Burke, a member of the Board of Directors of JP Morgan Chase & Co., is also a member of the Board of Directors of Berkshire Hathaway, and Todd Combs, Investment Officer of Berkshire Hathaway, is also a member of the Board of Directors of JP Morgan Chase & Co. In addition, J.P. Morgan and its affiliates hold, on a proprietary basis, less than 1% of the outstanding common stock of each of the Company and Berkshire Hathaway. In the ordinary course of their businesses, J.P. Morgan and its affiliates may actively trade the debt and equity securities or financial instruments (including derivatives, bank loans or other obligations) of the Company or Berkshire Hathaway for their own accounts or for the accounts of customers and, accordingly, they may at any time hold long or short positions in such securities or financial instruments.

Financing

The merger is not conditioned upon the receipt of financing by Knauf.

In connection with the execution of the merger agreement, on June 8, 2018, Knauf and Merger Sub entered into the debt commitment letter, pursuant to which Knauf will obtain debt financing for the merger that will be used, together with other available capital resources of Knauf and its subsidiaries, to fund (i) the payment of the closing consideration, (ii) the payment of all unpaid transaction fees to be paid in connection with completion of the merger and any amounts required to be paid by Knauf pursuant to the terms of the merger agreement, (iii) the repayment of certain existing indebtedness of the Company and its affiliates and (iv) the payment of any fees associated with the foregoing. The debt commitment letter provides, among other things, that UniCredit Bank AG and Commerzbank Aktiengesellschaft will arrange, manage the syndication of and underwrite a EUR 2,250,000,000 term credit facility, a EUR 500,000,000 (or the equivalent in U.S. dollars) revolving credit facility, a $800,000,000 term credit facility and a $858,500,000 backstop credit facility. The merger agreement requires that Knauf deliver to the Company a copy of the executed debt commitment letter, including all exhibits, schedules or amendments (if any) thereto.

Knauf has represented in the merger agreement that it will have sufficient funds available to it, through the aggregate proceeds from the foregoing credit facilities, together with the other available capital resources of Knauf and its subsidiaries, necessary to complete the merger and the other transactions contemplated by the merger agreement. The Company has agreed to use its reasonable best efforts to provide cooperation as may be reasonably requested by Knauf to assist Knauf in arranging, obtaining and syndicating debt financing at or prior to the effective time of the merger.

See the section entitled “The Merger Agreement—Financing and Financing Assistance.”

Interests of Our Directors and Executive Officers in the Merger

In considering the recommendation of the Board that you vote “FOR” adoption of the merger agreement, you should be aware that our directors and executive officers have potential interests in the proposed merger that may be different from or in addition to your interests generally. The Board was aware of these interests and considered them, among other matters, in approving the merger agreement, and in making its recommendation that you vote “FOR” adoption of the merger agreement. See the section entitled “Proposal 1: The Merger—Background of the Merger” and the section entitled “Proposal 1: The Merger—Recommendations of the Board

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and Reasons for the Merger.” These interests are described in more detail below, and certain of them are quantified in the narrative and the table below.

Directors and Executive Officers

Our directors and executive officers (serving in such roles in 2017 and/or 2018) are:

Like all other holders of shares of our common stock, our directors and executive officers will be entitled to receive closing consideration for each of their shares of our common stock, if any, and each of their outstanding Company equity awards will receive the treatment described below upon the completion of the merger.

Treatment of Company Equity Awards

Stock Options. At the effective time of the merger, each award of Company stock options in respect of our common stock that is outstanding immediately prior to the effective time of the merger will be converted into the right to receive a cash payment as promptly as practicable, but in no event later than 15 calendar days after the effective time of the merger, equal to the product of (i) the number of shares of our common stock subject to such Company stock option as of the effective time of the merger, multiplied by (ii) the excess, if any, of the closing consideration over the exercise price for such option.

Restricted Stock Unit Awards. At the effective time of the merger, each Company RSU Award in respect of our common stock that is outstanding immediately prior to the effective time of the merger, will become fully vested and will be converted into the right to receive as promptly as practicable, but in no event later than 15 calendar days after the effective time of the merger, a cash payment equal to the product of (i) the number of

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shares of our common stock subject to such Company RSU Award as of the effective time of the merger, multiplied by (ii) the closing consideration; provided that to the extent any such Company RSU Award constitutes nonqualified deferred compensation subject to Section 409A of the Code, such cash payment will be paid in accordance with the applicable award’s terms and at the earliest time permitted under the terms of such award that will not result in the application of a tax or penalty under Section 409A of the Code. If stockholder approval of the adoption of the merger agreement is obtained, each holder of any Company RSU Awards, outstanding as of the record date of the special meeting, will receive a dividend equivalent in an amount equal to the product of (i) the conditional special dividend, and (ii) the number of shares underlying such Company RSU Award in accordance with the terms of such award. The dividend equivalent will be converted into additional Company RSU Awards that will vest and be paid out along with the other outstanding Company RSU Awards as promptly as practicable, but in no event later than 15 calendar days after the effective time of the merger.

Market Share Unit Awards and Performance Share Awards. At the effective time of the merger, each Company MSU Award and each Company Performance Share Award in respect of our common stock that is outstanding immediately prior to the effective time of the merger will become fully vested and will be converted into the right to receive as promptly as practicable, but in no event later than 15 calendar days after the effective time of the merger, a cash payment equal to the product of (i) (a) in the case of a Company MSU Award, the number of shares of our common stock earned under such Company MSU Award, determined as of the effective time of the merger by substituting the closing consideration for the market value per share, or (b) in the case of a Company Performance Share Award, the number of shares of our common stock earned under such Company Performance Share Award, determined by substituting the closing consideration for the ending stock price in determining the achievement of the performance goal measured as of the effective time of the merger, multiplied by (ii) the closing consideration; provided that to the extent any such Company MSU Award or Company Performance Share Award constitutes nonqualified deferred compensation subject to Section 409A of the Code, such cash payment will be paid in accordance with the applicable award’s terms and at the earliest time permitted under the terms of such award that will not result in the application of a tax or penalty under Section 409A of the Code. Any shares of our common stock subject to a Company MSU Award or a Company Performance Share Award not earned on the effective date of the merger will be forfeited.

Deferred Stock Unit Awards. Pursuant to the merger agreement, it is expected that all of the Company’s non-employee directors will be replaced as of the effective time of the merger. Accordingly, at the effective time of the merger, each Company DSU Award held in notional accounts by non-employee directors who will experience a “separation from service” under Section 409A of the Code in connection with the completion of the merger, will be converted into a right to receive a cash payment equal to the product of (i) the number of shares of our common stock deemed to be held in the notional account immediately before the effective time of the merger, multiplied by (ii) the closing consideration; provided that (a) to the extent that any such non-employee director is a “specified employee” under Section 409A of the Code or (b) such non-employee director does not have a “separation from service” in connection with the completion of the merger, such cash payment will be paid in accordance with the applicable Company DSU Award’s terms and at the earliest time permitted under the terms of such award that will not result in the application of a tax or penalty under Section 409A of the Code. If stockholder approval of the adoption of the merger agreement is obtained, each holder of any Company DSU Awards, outstanding as of the record date of the special meeting, will receive a dividend equivalent in an amount equal to the product of (i) the conditional special dividend, multiplied by (ii) the number of shares underlying such Company DSU Award in accordance with the terms of such award.

Dividend Make-Whole Amounts. The Company will grant a Dividend Make-Whole Amount to each holder of Incentive Equity Awards that were outstanding as of June 10, 2018, which are not entitled to dividend equivalent payments, in the form of a cash payment in an amount equal to the product of (i) the conditional special dividend, multiplied by (ii) the number of shares of common stock that either (a) are or become vested and paid out on such Incentive Equity Awards in connection with the completion of the merger and did not otherwise participate in the conditional special dividend, or (b) subject to the applicability of due bill trading, are or become vested and become payable following the record date, but prior to the closing date of the merger, in each case as determined by the Company. The Dividend Make-Whole Amount will be earned upon the effective

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time of the merger subject to the holder of the underlying Incentive Equity Award remaining continuously employed by the Company and its subsidiaries until immediately prior to the effective time of the merger, and will be paid promptly thereafter, but in no event later than 15 days following the effective time of the merger. However, if any holder of outstanding Incentive Equity Awards terminates employment with the Company or any of its subsidiaries prior to the effective time of the merger, and any such Incentive Equity Awards remain outstanding following such termination in accordance with their terms, then such holder will still be eligible to receive a Dividend Make-Whole Amount with respect to such outstanding Incentive Equity Awards.

For an estimate of the amounts that would become payable to each of USG’s named executive officers in settlement of his or her outstanding equity awards, see the section entitled “—Quantification of Potential Payments to Our Named Executive Officers in Connection with the Merger.” If the effective time of the merger were August 1, 2018, based on the number of equity awards outstanding as of such date, the closing consideration of $43.50 per share of our common stock, and the conditional special dividend of $0.50, we estimate the amount that would become payable to each of the nine individuals who were executive officers of the Company in either 2017 or 2018 other than its named executive officers in payment for their outstanding shares of our common stock held directly and indirectly and in settlement of their outstanding equity awards (including any related dividend equivalents, such as the conditional special dividend, with respect to Company RSU Awards, the Dividend Make-Whole Amounts with respect to Company stock options, Company MSU Awards and Company Performance Share Awards, and less, for Company stock options, the exercise price) as follows:

If the effective time of the merger were August 1, 2018, based on the number of equity awards outstanding as of such date, the closing consideration of $43.50 per share of our common stock, and the conditional special dividend of $0.50, we estimate the amount that would become payable to each of the Company’s eight non-employee directors in payment for their outstanding shares of our common stock held directly and indirectly and in settlement of their outstanding equity awards (including any related dividend equivalents, such as the conditional special dividend, with respect to Company DSU Awards) as follows:

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The amount payable in respect of the Company’s executive officers does not reflect certain compensation actions that may occur before the effective time of the merger, including the grant of any additional equity awards as permitted by the merger agreement.

Change in Control Severance Agreements

The Company is party to change in control severance agreements with each of Brian Cook, Dominic Dannessa, Matthew Hilzinger, Joseph Holmes, Christopher Macey, Mary Martin, John Reale, Gregory Salah, Jennifer Scanlon and Michelle Warner, which provide severance benefits upon a qualifying termination of employment. If the employment of such person is terminated by the Company without cause or by the executive officer for good reason within two years following, or terminated by the Company without cause within 120 days (or 90 days, in the case of Mary Martin) prior to, a change in control of the Company (such as the merger) in accordance with the terms of their change in control severance agreements, each such person would be entitled to the following payments and benefits:

In addition, in the event of a termination without cause within 120 days (or 90 days, in the case of Mary Martin) prior to a change in control, any equity awards forfeited as a result of the executive officer’s termination will be cashed out following such change in control.

The agreements with Brian Cook, Dominic Dannessa, Mary Martin and Jennifer Scanlon also provide that if the applicable executive officer’s severance benefits constitute in aggregate a parachute payment, the aggregate amount will be cutback by the smallest amount necessary to eliminate the parachute amount, unless the cutback would reduce the value of the aggregate severance benefits by 10% or more, in which case, it will be grossed up (in the case of Mary Martin such gross up payment will not include any amount in respect of taxes imposed on health insurance benefits). The change in control severance agreements with each of Matthew Hilzinger, Joseph Holmes, Christopher Macey, John Reale, Gregory Salah, and Michelle Warner provide that if any payments thereunder are subject to an excise tax under Section 4999 of the Code, such payments will be reduced to the extent that the reduction would result in a greater after-tax benefit to the executive officer.

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As a condition to receiving the severance benefits under the change in control severance agreements, the applicable executive officer must execute a release of claims. The change in control severance agreements also include one-year post-employment non-competition restrictive covenants and two-year (three years in the case of Brian Cook) post-employment non-solicitation restrictive covenants.

For an estimate of the amounts that would become payable to each of the Company’s named executive officers under his or her change in control severance agreement if a severance-qualifying termination of employment were to occur immediately following consummation of the merger, see the section entitled “—Quantification of Potential Payments to Our Named Executive Officers in Connection with the Merger.” If the effective time of the merger were August 1, 2018, we estimate that the aggregate value of the pro-rated annual bonus payment, severance payment, cash payment for an additional six months of health and welfare benefits coverage, pension-related payment, tax reimbursements and ancillary outplacement benefits that would become payable to each of Dominic Dannessa, Joseph Holmes, Christopher Macey, Mary Martin and John Reale under their change in control severance agreements, if each incurred a severance-qualifying termination of employment on that date, would be as follows:

Pro-rated Annual Bonus for USG’s 2018 Fiscal Year

Pursuant to the merger agreement, if the merger is completed prior to the end of the Company’s 2018 fiscal year, the Company may pay annual bonus awards to eligible employees (including the executive officers), who continue to be employed on the closing date of the merger, in an amount determined based on actual performance as determined in good faith by the Compensation and Organization Committee of the Board and pro-rated based on the portion of the year elapsed as of the closing date. If the effective time of the merger occurs on or after the last day of the Company’s fiscal year 2018, the Company may pay full annual bonus awards for fiscal year 2018 to eligible employees (including the executive officers), who continue to be employed on the last day of the Company’s 2018 fiscal year, the amount of which will be determined based on the actual level of achievement of the applicable performance goals as determined in good faith by the Compensation and Organization Committee of the Board.

Dividend Make-Whole Amounts

The Company will grant a Dividend Make-Whole Amount to each holder of Incentive Equity Awards that were outstanding as of June 10, 2018, which are not entitled to dividend equivalent payments, in the form of a cash payment in an amount equal to the product of (i) the conditional special dividend, multiplied by (ii) the number of shares of our common stock that either (a) are or become vested and paid out on such Incentive Equity Awards in connection with the completion of the merger and did not otherwise participate in the conditional special dividend, or (b) subject to the applicability of due bill trading, are or become vested and become payable following the record date, but prior to the closing date of the merger, in each case as determined by the Company. The Dividend Make-Whole Amount will be earned upon the effective time of the merger subject to the holder of the underlying Incentive Equity Award remaining continuously employed by the Company and its subsidiaries until immediately prior to the effective time of the merger, and will be paid promptly thereafter, but in no event

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later than 15 days following the effective time of the merger. However, if any holder of outstanding Incentive Equity Awards terminates employment with the Company or any of its subsidiaries prior to the effective time of the merger, and any such Incentive Equity Awards remain outstanding following such termination in accordance with their terms, then such holder will still be eligible to receive a Dividend Make-Whole Amount with respect to such outstanding Incentive Equity Awards.

For an estimate of the amounts that are expected to become payable to each of the Company’s named executive officers under his or her Dividend Make-Whole Amount upon the completion of the merger, see the section entitled “—Quantification of Potential Payments to Our Named Executive Officers in Connection with the Merger.” If the effective time of the merger were August 1, 2018, we estimate that the amount that would become payable to each of Kenneth Banas, Dominic Dannessa, Joseph Holmes, Christopher Macey, Mary Martin, Jeanette Press, John Reale, Chris Rosenthal and Srinivas Veeramasuneni under their Dividend Make-Whole Amounts, which are included in the tabular disclosure of the amounts that would become payable to such executive officers in settlement of their shares and outstanding equity awards, would be as follows:

New Management Arrangements

As of the date of this proxy statement, there are no employment, equity contribution or other agreements between any of the Company’s executive officers or directors, on the one hand, and the Company or Knauf, on the other hand, in each case that have been requested or initiated by Knauf. The merger is not conditioned upon any executive officer or director of the Company entering into any such agreement.

Indemnification; Directors’ and Officers’ Insurance

Pursuant to the merger agreement, from and after the effective time of the merger, Knauf will indemnify certain persons, including the Company’s directors and officers. In addition, for a period of six years from the effective time of the merger, Knauf will maintain an insurance and indemnification policy for the benefit of certain persons, including the Company’s directors and officers. For additional information, see the section entitled “The Merger Agreement—Indemnification and Insurance.”

Quantification of Potential Payments to Our Named Executive Officers in Connection with the Merger

The information set forth in the table below is intended to comply with Item 402(t) of Regulation S-K, which requires disclosure of information about certain compensation for each of the Company’s named executive officers that is based on or otherwise relates to the merger. For additional details regarding the terms of the payments described below, see the discussion under the caption “—Interests of Our Directors and Executive Officers in the Merger.” For information regarding shares of our common stock held by the named executive officers that would be entitled to receive the total consideration payable in connection with the merger, see the tabular disclosure under the caption “Security Ownership of Certain Beneficial Owners and Management.”

The amounts indicated below are estimates based on multiple assumptions that may or may not actually occur or be accurate on the relevant date, including assumptions described below, and do not reflect certain

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compensation actions that may occur before the effective time of the merger, including the grant of any additional equity awards as permitted by the merger agreement. For purposes of calculating such amounts, we have assumed:

in each case, payable in a lump sum on the 61^st day following the termination of employment of such named executive officer by the Company without cause or by the named executive officer for good reason within two years following, or by the Company without cause within 120 days prior to, a change in control of the Company (such as the merger); and

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The components of such cash amount payable pursuant to the change in control severance agreements are “double-trigger” (i.e., they are contingent upon a qualifying termination of employment), and the 2018 annual bonus award component of such cash amount is single-trigger and will become payable upon the completion of the merger. As a condition to receiving the severance benefits under the change in control severance agreements, the named executive officers must execute a release of claims. The change in control severance agreements also include one-year post-employment non-competition restrictive covenants and two-year (three years in the case of Brian Cook) post-employment non-solicitation restrictive covenants. The estimated amount of each component of the cash payment is set forth in the table below.

The amounts above and in the table below assume the closing consideration as the price per share of our common stock. Set forth below are the values of each type of outstanding Equity Award (including any related dividend equivalents) held by the named executive officers that would become vested and paid out upon the completion of the merger. These amounts do not include any Dividend Make-Whole Amount payments, which are reflected in the “Other” column in the table above.

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Material U.S. Federal Income Tax Consequences of the Merger and the Conditional Special Dividend

The following is a discussion of the material U.S. federal income tax consequences of the merger and the conditional special dividend to holders of our common stock who receive the conditional special dividend and whose shares of our common stock are exchanged for the closing consideration pursuant to the merger. This discussion is based on the provisions of the Code, applicable U.S. Treasury Regulations, judicial opinions and administrative rulings and published positions of the Internal Revenue Service (the “IRS”), each as in effect as of the date hereof. These authorities are subject to change or differing interpretations, possibly on a retroactive basis, and any such change or interpretation could affect the accuracy of the statements and conclusions set forth in this discussion. This discussion does not address any tax consequences arising under the unearned income Medicare contribution tax pursuant to the Health Care and Education Reconciliation Act of 2010, nor does it address any tax considerations under state, local or foreign laws or U.S. federal laws other than those pertaining to the U.S. federal income tax. This discussion is not binding on the IRS or the courts and, therefore, could be subject to challenge, which could be sustained. No ruling will be sought from the IRS with respect to the merger or the conditional special dividend.

This discussion applies only to beneficial owners of shares of our common stock who hold such shares as a capital asset within the meaning of Section 1221 of the Code (generally, property held for investment). Further, this discussion does not purport to consider all aspects of U.S. federal income taxation that may be relevant to a holder in light of its particular circumstances, or that may apply to holders subject to special treatment under U.S. federal income tax laws (including, for example, insurance companies, dealers or brokers in securities or foreign currencies, traders in securities who elect to apply the mark-to-market method of accounting, holders subject to the alternative minimum tax, U.S. holders (as defined below) that have a functional currency other than the U.S. dollar, tax-exempt organizations, tax-qualified retirement plans, banks and other financial institutions, mutual funds, certain former citizens or former long-term residents of the United States, partnerships or other entities or arrangements treated as partnerships for U.S. federal income tax purposes or other flow-through entities (and investors therein), S corporations, real estate investment trusts, regulated investment companies, controlled foreign corporations, passive foreign investment companies, U.S. holders who hold shares of our common stock

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as part of a hedge, straddle, constructive sale, conversion or other integrated transaction, and U.S. holders who acquired their shares of our common stock through the exercise of employee stock options or other compensation arrangements). This discussion also does not address the U.S. federal income tax consequences to holders of shares of our common stock who exercise appraisal rights in connection with the merger under the DGCL.

If a partnership (including for this purpose any entity or arrangement treated as a partnership for U.S. federal income tax purposes) holds shares of our common stock, the tax treatment of a partner in such partnership will generally depend on the status of the partners and the activities of the partnership. If you are, for U.S. federal income tax purposes, a partner in a partnership holding shares of our common stock, you should consult your tax advisor.

Stockholders are urged to consult their own tax advisors to determine the particular tax consequences to them of the merger and the conditional special dividend, including the applicability and effect of the alternative minimum tax, the unearned income Medicare contribution tax and any other U.S. federal, or state, local, foreign or other tax laws.

Certain U.S. Federal Income Tax Consequences to U.S. Holders

This section applies to you if you are a U.S. holder. For purposes of this discussion, the term “U.S. holder” means a beneficial owner of our common stock that is for U.S. federal income tax purposes:

The conditional special dividend will be characterized as a dividend for U.S. federal income tax purposes to the extent paid out of the Company’s current or accumulated earnings and profits, as determined for U.S. federal income tax purposes. Such dividends are taxed at ordinary income tax rates; provided, however, that for a non-corporate U.S. holder, the amount of the conditional special dividend that is treated as a dividend for U.S. federal income tax purposes generally will be eligible under current law for a reduced rate of taxation if certain holding period and other requirements are satisfied. To the extent that the conditional special dividend qualifies for such reduced rate of taxation and constitutes an “extraordinary dividend” (generally, where the amount of the dividend exceeds 10% of a holder’s tax basis in its stock, the conditional special dividend will likely be an “extraordinary dividend”), any loss on the sale or exchange of such stock by a non-corporate U.S. holder, to the extent of such extraordinary dividend, will be treated as long-term capital loss. For a corporate U.S. holder, the amount of the conditional special dividend that is treated as a dividend for U.S. federal income tax purposes will be eligible for the dividends-received deduction if such holder meets certain holding period and other applicable requirements. In addition, if (i) a corporate U.S. holder is allowed a dividends-received deduction with respect to the conditional special dividend, (ii) such corporate U.S. holder held its common stock for two years or less, and (iii) such conditional special dividend constitutes an extraordinary dividend, then such corporate U.S. holder’s tax basis in its common stock will be reduced (but not below zero) by the nontaxed portion of the conditional special dividend and, if the nontaxed portion of such dividend exceeds such tax basis, such excess will be treated as gain from the sale or exchange of such holder’s common stock.

Based on the Company’s estimate of its current and accumulated earnings and profits, it currently expects that only a portion of the amount of the conditional special dividend will be paid out of earnings and profits and

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thus treated as a dividend for U.S. federal income tax purposes; however, the Company will not make a final determination of the portion of the conditional special dividend that is treated as paid out of current and accumulated earnings and profits until after the close of the taxable year in which the conditional special dividend is paid. To the extent that the conditional special dividend exceeds the Company’s current and accumulated earnings and profits, the excess will first reduce the U.S. holder’s basis in our common stock, but not below zero, and then will be treated as gain from the sale of the U.S. holder’s common stock.

Assuming that the conditional special dividend is paid in 2018, the process of determining current and accumulated earnings and profits requires a final determination of the 2018 fiscal year results and a review of certain other factors. The determination will be based in part on factors that are outside of the control of the Company and which cannot be ascertained at this time. The Company will be required to complete IRS Form 8937 for certain distributions that affect stockholder basis, including the payment of the conditional special dividend, and post it on its website within 45 days of the dividend payment date. The Company expects that this form will provide certain preliminary information on the expected changes in the tax basis of the shares and the portion of the conditional special dividend anticipated to be paid out of earnings and profits. The final determination of the tax treatment of annual distributions (dividends versus return of capital) is reported to U.S. stockholders on IRS Form 1099-DIV. This form will be mailed to U.S. stockholders in early 2019, assuming the conditional special dividend is paid in 2018. The Company’s determination of current and accumulated earnings and profits is not binding on the IRS, and it is possible that the IRS will take a different view.

The receipt of the closing consideration by U.S. holders in exchange for shares of common stock pursuant to the merger will be a taxable transaction for U.S. federal income tax purposes. In general, for U.S. federal income tax purposes, a U.S. holder who receives the closing consideration in exchange for shares of common stock pursuant to the merger will recognize capital gain or loss in an amount equal to the difference, if any, between (i) the amount of cash received and (ii) the U.S. holder’s adjusted tax basis in such shares. A U.S. holder’s adjusted tax basis in the shares of common stock generally will equal the holder’s purchase price for such shares, as adjusted to take into account stock dividends, stock splits, distributions not treated as a dividend or similar transactions.

Any such gain or loss will be long-term capital gain or loss if a U.S. holder’s holding period in the shares of common stock surrendered in the merger is greater than one year as of the date of the merger. Long-term capital gains of certain non-corporate U.S. holders, including individuals, are generally subject to U.S. federal income tax at preferential rates. The deductibility of capital losses is subject to limitations. If a U.S. holder acquired different blocks of common stock at different times and different prices, such U.S. holder must determine its adjusted tax basis, gain or loss and holding period separately with respect to each block of common stock.

Certain U.S. Federal Income Tax Consequences to Non-U.S. Holders

This section applies to you if you are a non-U.S. holder. You are a “non-U.S. holder” if you are neither a U.S. holder nor a partnership. Also, you are not a non-U.S. holder if you are a nonresident alien individual present in the United States for 183 days or more in the taxable year of the special dividend or merger, in which case you should consult your tax advisor regarding the U.S. federal income tax consequences of the conditional special dividend or merger.

The amount of the conditional special dividend that is treated as a dividend for U.S. federal income tax purposes generally will be subject to withholding tax at a 30% rate or a reduced rate specified by an applicable income tax treaty (except as described in the immediately succeeding paragraph). While the Company expects that only a portion of the conditional special dividend will be treated as a dividend for U.S. federal income tax purposes, the Company will not make a final determination of the amount treated as a dividend until after the close of the taxable year in which the conditional special dividend is paid. Accordingly, the Company expects that, if withholding is required, it or another applicable withholding agent will withhold based on the entire amount of the conditional special dividend. In such event, a non-U.S. holder may seek a refund from the IRS

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with respect to withholdings on amounts in excess of the portion treated as a dividend for U.S. federal income tax purposes. Non-U.S. holders should consult their tax advisors on how to obtain a refund of any excess withholding. To obtain a reduced rate of withholding, a non-U.S. holder will be required to provide a properly executed applicable IRS Form W-8 certifying such non-U.S. holder’s entitlement to benefits under a treaty. A non-U.S. holder will generally not be subject to tax on any gain recognized with respect to its common stock either on account of the conditional special dividend or pursuant to the merger (except as described in the immediately succeeding paragraph).

If the conditional special dividend or any gain realized by a non-U.S. holder pursuant to the merger is effectively connected with such non-U.S. holder’s conduct of a U.S. trade or business, and, if required by an applicable income tax treaty, is attributable to a permanent establishment or fixed base maintained by such non-U.S. holder in the United States, the conditional special dividend and any gain realized by a non-U.S. holder pursuant to the merger generally will be subject to U.S. federal income tax on a net income basis in the same manner as if such holder were a U.S. holder. In this case, with respect to the conditional special dividend, a non-U.S. holder will be exempt from the withholding tax discussed above, although such holder will be required to provide a properly executed IRS Form W-8ECI in order to claim an exemption from withholding. A non-U.S. holder should consult its tax advisor with respect to other U.S. federal income tax consequences of the conditional special dividend and the merger, including the possible imposition of a branch profits tax at a rate of 30% (or lower treaty rate) if such U.S. holder is a corporation.

FATCA

Provisions of the Code commonly referred to as “FATCA” require withholding of 30% on payments of dividends on our common stock (including the conditional special dividend), as well as payments of gross proceeds of dispositions of our common stock (including the closing consideration) occurring after December 31, 2018, to “foreign financial institutions” (which is broadly defined for this purpose and in general includes investment vehicles) and certain other non-U.S. entities unless various U.S. information reporting and due diligence requirements (generally relating to ownership by U.S. persons of interests in or accounts with those entities) have been satisfied, or an exemption applies. An intergovernmental agreement between the United States and an applicable foreign country may modify these requirements. If FATCA withholding is imposed, a beneficial owner that is not a foreign financial institution generally may obtain a refund of any amounts withheld by filing a U.S. federal income tax return (which may entail significant administrative burden). You should consult your tax advisor regarding the effects of FATCA on your receipt of the conditional special dividend and the closing consideration.

Information Reporting and Backup Withholding

Payments of the conditional special dividend and payments made in exchange for shares of common stock pursuant to the merger may be subject, under certain circumstances, to information reporting and backup withholding (currently at a rate of 24%). To avoid backup withholding, a U.S. holder that does not otherwise establish an exemption should complete and return to the applicable withholding agent a properly completed and executed IRS Form W-9, certifying that such U.S. holder is a U.S. person, that the taxpayer identification number provided is correct, and that such U.S. holder is not subject to backup withholding. Non-U.S. holders are generally exempt from backup withholding and should establish their exemption by certifying as to their non-U.S. status on an appropriate IRS Form W-8.

Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules may be refunded or credited against a holder’s U.S. federal income tax liability, if any, provided that such holder furnishes the required information to the IRS in a timely manner.

Regulatory Approvals

Under the HSR Act and related rules, certain transactions, including the merger, may not be completed until notifications have been submitted to the Antitrust Division and the FTC and the applicable statutory waiting

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period has expired or been terminated. The Company and Knauf received notice that their request for early termination of the HSR waiting period was granted on July 11, 2018. HSR clearance for the merger is effective as of receipt of that notice. Completion of the merger is further subject to notification or receipt of certain other regulatory approvals, including notification, clearance and/or approval in certain foreign jurisdictions, including Australia, China, Mexico, New Zealand, Singapore and Vietnam. The parties have filed or are in the process of preparing required notifications in each of the other applicable filing jurisdictions.

At any time, non-U.S. regulatory bodies and U.S. state attorneys general could take action under the antitrust laws as they deem necessary or desirable in the public interest, including seeking to enjoin the completion of the merger or permitting completion subject to regulatory conditions. Private parties may also seek to take legal action under the antitrust laws under some circumstances. There can be no assurance that a challenge to the merger on antitrust grounds will not be made or, if such a challenge is made, that it would not be successful.

Pursuant to the merger agreement, Knauf is required to take all actions necessary to obtain antitrust approvals, including (i) proposing, negotiating, committing to and effecting, by consent decree, hold separate order, or otherwise, the sale, divestiture or disposition of such businesses, product lines or assets of Knauf and its respective subsidiaries and affiliates and (ii) otherwise taking or committing to take actions that, after the effective time of the merger, would limit Knauf’s or its subsidiaries’ or affiliates’ freedom of action with respect to, or its or their ability to retain, one or more of the businesses, product lines or assets of Knauf and its respective subsidiaries or affiliates.

Regulatory authorities may impose conditions on the completion of the merger. While Knauf is required in accordance with the merger agreement to take all actions necessary to procure approvals from regulatory authorities, there can be no assurance that the merger will be completed in the expected timeframe if regulatory authorities impose such conditions.

Litigation Relating to the Merger

On August 13, 2018, a purported stockholder of the Company filed a putative class action against the Company, its directors, Knauf, C&G Verwaltungs GmbH (an indirect subsidiary of Knauf), Merger Sub, and Berkshire captioned Anderson v. USG Corporation, et. al., Case No. 2018-0602, in the Court of Chancery of the State of Delaware. Also on August 13, 2018, a second purported stockholder of the Company filed a putative class action against the Company, its directors, Knauf, C&G Verwaltungs GmbH, Merger Sub, and Berkshire captioned Fitzgerald v. USG Corporation, et. al., Case No. 2018-0603, in the Court of Chancery of the State of Delaware. In each action, the complaint alleges violations of Section 203 of the DGCL in connection with the merger, breach of fiduciary duty, and aiding and abetting breach of fiduciary duty. The complaints seek class action certification and a variety of relief including, among other things, an injunction preventing the stockholder vote regarding adoption of the merger agreement or completion of the merger, or, in the event the merger is completed, rescission of the merger or an award of rescissory damages, plus attorneys’ fees and costs.

The complaints allege, among other things, that the merger triggers the voting requirements of Section 203 of the DGCL which, if applicable, would require the affirmative vote of 66 ²⁄₃% of the outstanding shares of our common stock not owned by Knauf, Berkshire, and their affiliates to complete the merger. The complaints allege that Section 203 is triggered because, prior to the Board’s approval of the merger, Knauf and Berkshire purportedly had an “agreement, arrangement and/or understanding” with respect to the merger. In addition, the complaint alleges that the merger constitutes “a hostile takeover attempt governed by Section 203” of the DGCL. The Company believes the allegations in the complaints are without merit. The Company further notes that if the voting requirements of Section 203 of the DGCL applied to the merger, the voting requirements of Section 203 of the DGCL would mean that an affirmative vote of the holders of 80.56% of our outstanding shares of our common stock would be required, rather than the affirmative vote of the holders of 80% of our outstanding shares of our common stock required under our certificate of incorporation of the Company.

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The Company believes the claims in each complaint are without merit. At this time, however, it is not possible to predict the outcome of these matters or their effects on the Company or the merger.

Additional lawsuits arising out of or relating to the merger may be filed in the future.

Delisting and Deregistration of Company Common Stock

If the merger is completed, all shares of our common stock will be delisted from the NYSE and the CHX and deregistered under the Exchange Act.

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THE MERGER AGREEMENT

The following is a summary of the material provisions of the merger agreement, a copy of which is attached to this proxy statement as Annex A and which is incorporated by reference into this proxy statement. This summary does not purport to be complete and may not contain all of the information about the merger agreement that is important to you. We encourage you to read carefully the merger agreement in its entirety, as the rights and obligations of the parties thereto are governed by the express terms of the merger agreement and not by this summary or any other information contained in this proxy statement.

Explanatory Note Regarding the Merger Agreement

The following summary of the merger agreement, and the copy of the merger agreement attached as Annex A to this proxy statement, are intended to provide information regarding the terms of the merger agreement and are not intended to provide any factual information about the Company or to modify or supplement any factual disclosures about the Company in its public reports filed with the SEC. In particular, the merger agreement and the related summary are not intended to be, and should not be relied upon as, disclosures regarding any facts and circumstances relating to the Company. The merger agreement contains representations and warranties by and covenants of the Company, Knauf and Merger Sub, and they were made only for purposes of that agreement and as of specified dates. The representations, warranties and covenants in the merger agreement were made solely for the benefit of the parties to the merger agreement, may be subject to limitations, qualifications and other particulars agreed upon by the contracting parties, including being qualified by confidential disclosures made for the purposes of allocating contractual risk between the parties to the merger agreement instead of establishing these matters as facts or being made for other purposes, and may be subject to contractual standards of materiality or material adverse effect (as defined below) applicable to the contracting parties that generally differ from those applicable to investors. In addition, information concerning the subject matter of the representations, warranties and covenants may change after the date of the merger agreement, which subsequent information may or may not be fully reflected in the Company’s public disclosures. The representations, warranties and covenants in the merger agreement and any descriptions thereof should be read in conjunction with the disclosures elsewhere in this proxy statement and in the Company’s periodic and current reports, proxy statements and other documents filed with the SEC. See the section entitled “Where You Can Find Additional Information.”

Structure of the Merger; Certificate of Incorporation; Bylaws; Directors and Officers

At the effective time of the merger, Merger Sub will merge with and into the Company, and the separate corporate existence of Merger Sub will cease. The Company will be the surviving corporation in the merger and will continue its corporate existence as a Delaware corporation and an indirect, wholly-owned subsidiary of Knauf. The certificate of incorporation of the Company that is in effect immediately before the effective time of the merger will be amended and restated to read in its entirety as set forth in Exhibit B to the merger agreement, and as so amended will become the certificate of incorporation of the surviving corporation. The bylaws of the Company that are in effect immediately before the effective time of the merger will be amended and restated to read in their entirety as set forth in Exhibit C to the merger agreement, and as so amended will become the bylaws of the surviving corporation.

The individuals holding positions as directors of Merger Sub at the effective time of the merger will become the initial directors of the surviving corporation. The individuals holding positions as officers of the Company at the effective time of the merger will become the initial officers of the surviving corporation.

When the Merger Becomes Effective

The closing of the merger (the “closing”) will take place at the offices of Baker & McKenzie, LLP, 300 East Randolph Street, Chicago, Illinois 60601, at 10:00 a.m., Chicago time, on the second business day following the day on which the last of the conditions set forth in the merger agreement to be satisfied or waived (other than

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those conditions that by their nature are to be satisfied at the closing, but subject to the satisfaction or waiver of those conditions) are satisfied or waived in accordance with the merger agreement, unless otherwise mutually agreed in writing between the Company and Knauf (the date on which the closing actually occurs is referred to herein as the “closing date”). For purposes of the merger agreement, “business day” refers to any day, except Saturday or Sunday, on which commercial banks are not required or authorized to close in Frankfurt, Germany, Chicago, Illinois, Dover, Delaware or New York, New York.

On the closing date, the Company and Knauf will file a certificate of merger with the Secretary of State of the State of Delaware. The merger will become effective at the time when the certificate of merger has been duly filed with the Secretary of State of the State of Delaware, or at such later time as may be agreed by the parties in writing and specified in the certificate of merger.

As of the date of this proxy statement, we expect to complete the merger in early 2019. However, completion of the merger is subject to the satisfaction or waiver of the conditions to the completion of the merger, which are described below and include stockholder approval of the adoption of the merger agreement and various regulatory clearances and approvals, and it is possible that the merger will not be completed until a later time, or at all. There may be a substantial amount of time between the special meeting and the completion of the merger. After obtaining stockholder approval of the adoption of the merger agreement, the Board will not have the right to terminate the merger agreement in order to accept any alternative acquisition proposal. We expect to complete the merger promptly following the receipt of all required approvals.

Effect of the Merger on the Common Stock

At the effective time of the merger, each share of the Company’s common stock issued and outstanding immediately prior to the effective time of the merger (other than shares of common stock owned by Knauf and its subsidiaries, the Company and its subsidiaries or excluded holders) will be converted into and represent the right to receive the closing consideration. The closing consideration will be $43.50 per share in cash, without interest and subject to tax withholding as applicable.

At the effective time of the merger, each share of the Company’s common stock owned by the Company or its subsidiaries will be cancelled and will cease to exist and no consideration will be paid or delivered in exchange therefor.

At the effective time of the merger, each share of the Company’s common stock owned by Knauf or any of its subsidiaries and each share of Merger Sub owned by Knauf or any of its subsidiaries immediately prior to the effective time of the merger will continue as one fully paid and non-assessable share of common stock, par value $0.10 per share, of the surviving corporation.

Treatment of Company Equity Awards

Stock Options. At the effective time of the merger, each award of Company stock options in respect of the Company’s common stock that is outstanding immediately prior to the effective time of the merger will be converted into the right to receive a cash payment as promptly as practicable, but in no event later than 15 calendar days after the effective time of the merger, equal to the product of (i) the number of shares of the Company’s common stock subject to such Company stock option as of the effective time of the merger, multiplied by (ii) the excess, if any, of the closing consideration over the exercise price for such Company stock option.

Restricted Stock Unit Awards. At the effective time of the merger, each Company RSU Award in respect of the Company’s common stock that is outstanding immediately prior to the effective time of the merger, will become fully vested and will be converted into the right to receive as promptly as practicable, but in no event later than 15 calendar days after the effective time of the merger, a cash payment equal to the product of (i) the

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number of shares of the Company’s common stock subject to such Company RSU Award as of the effective time of the merger, multiplied by (ii) the closing consideration; provided that to the extent any such Company RSU Award constitutes nonqualified deferred compensation subject to Section 409A of the Code, such cash payment will be paid in accordance with the applicable award’s terms and at the earliest time permitted under the terms of such award that will not result in the application of a tax or penalty under Section 409A of the Code. If stockholder approval of the adoption of the merger agreement is obtained, each holder of any Company RSU Awards, outstanding as of the record date of the special meeting, will receive a dividend equivalent in an amount equal to the product of (i) the conditional special dividend, and (ii) the number of shares underlying such Company RSU Award in accordance with the terms of such award.

Market Share Unit Awards and Performance Share Awards. At the effective time of the merger, each Company MSU Award and each Company Performance Share Award in respect of the Company’s common stock that is outstanding immediately prior to the effective time of the merger will become fully vested and will be converted into the right to receive as promptly as practicable, but in no event later than 15 calendar days after the effective time of the merger, a cash payment equal to the product of (i) (a) in the case of a Company MSU Award, the number of shares of the Company’s common stock earned under such Company MSU Award, determined as of the effective time of the merger by substituting the closing consideration for the market value per share, or (b) in the case of a Company Performance Share Award, the number of shares of the Company’s common stock earned under such Company Performance Share Award, determined by substituting the closing consideration for the ending stock price in determining the achievement of the performance goal measured as of the effective time of the merger, multiplied by (ii) the closing consideration; provided that to the extent any such Company MSU Award or Company Performance Share Award constitutes nonqualified deferred compensation subject to Section 409A of the Code, such cash payment will be paid in accordance with the applicable award’s terms and at the earliest time permitted under the terms of such award that will not result in the application of a tax or penalty under Section 409A of the Code. Any shares of the Company’s common stock subject to a Company MSU Award or a Company Performance Share Award not earned on the effective date of the merger will be forfeited.

Deferred Stock Unit Awards. Pursuant to the merger agreement, it is expected that all of the Company’s non-employee directors will be replaced as of the effective time of the merger. Accordingly, at the effective time of the merger, each Company DSU Award held in notional accounts by non-employee directors who will experience a “separation from service” under Section 409A of the Code in connection with the completion of the merger, will be converted into a right to receive a cash payment equal to the product of (i) the number of shares of the Company’s common stock deemed to be held in the notional account immediately before the effective time of the merger, multiplied by (ii) the closing consideration; provided that (a) to the extent that any such non-employee director is a “specified employee” under Section 409A of the Code or (b) such non-employee director does not have a “separation from service” in connection with the completion of the merger, such cash payment will be paid in accordance with the applicable Company DSU Award’s terms and at the earliest time permitted under the terms of such award that will not result in the application of a tax or penalty under Section 409A of the Code. If stockholder approval of the adoption of the merger agreement is obtained, each holder of any Company DSU Awards, outstanding as of the record date of the special meeting, will receive a dividend equivalent in an amount equal to the product of (i) the conditional special dividend, and (ii) the number of shares underlying such Company DSU Award in accordance with the terms of such award.

Dividend Make-Whole Amounts. The Company will grant a Dividend Make-Whole Amount to each holder of Incentive Equity Awards that were outstanding as of June 10, 2018, which are not entitled to dividend equivalents, in the form of a cash payment in an amount equal to the product of (i) the conditional special dividend, multiplied by (ii) the number of shares of common stock that either (a) are or become vested and paid out on such Incentive Equity Awards in connection with the completion of the merger and did not otherwise participate in the conditional special dividend, or (b) subject to the applicability of due bill trading, are or become vested and become payable following the record date, but prior to the closing date of the merger, in each case as determined by the Company. The Dividend Make-Whole Amount will be earned upon the effective time of the

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merger subject to the holder of the underlying Incentive Equity Award remaining continuously employed by the Company and its subsidiaries until immediately prior to the effective time of the merger, and will be paid promptly thereafter, but in no event later than 15 days following the effective time of the merger. However, if any holder of outstanding Incentive Equity Awards terminates employment with the Company or any of its subsidiaries prior to the effective time of the merger, and any such Incentive Equity Awards remain outstanding following such termination in accordance with their terms, then such holder will still be eligible to receive a Dividend Make-Whole Amount with respect to such outstanding Incentive Equity Awards.

Payment for Common Stock in the Merger

At the effective time of the merger, Knauf will deposit, or cause to be deposited, in trust with a paying agent in a separate account for the benefit of the holders of the Company’s common stock, cash in U.S. dollars sufficient to pay the closing consideration in exchange for all of the shares of the Company’s common stock issued and outstanding immediately prior to the effective time of the merger (other than shares of common stock owned by Knauf and its subsidiaries, the Company and its subsidiaries or excluded holders). As soon as reasonably practicable after the effective time of the merger and in any event no later than the second business day following the closing date, the surviving corporation will cause the paying agent to mail to each holder of record of shares of the Company’s common stock converted into the right to receive a portion of the closing consideration (i) a letter of transmittal and (ii) instructions for use in effecting the surrender of the certificates or book-entry shares in exchange for payment of the closing consideration. Upon surrender of certificates or book-entry shares to the paying agent together with such letter of transmittal, duly completed and validly executed in accordance with the instructions, and such other documents as may be customarily required by the paying agent, the holder of such certificates or book-entry shares will be entitled to receive an amount in cash equal to the product of (i) the number of shares represented by such holder’s properly surrendered certificates or book-entry shares multiplied by (ii) the closing consideration.

Conditional Special Dividend

In addition to the closing consideration, as contemplated in the merger agreement, the Company declared the conditional special dividend of $0.50 per share payable to holders of the Company’s common stock as of the record date of the special meeting. Payment of the conditional special dividend is conditioned on obtaining stockholder approval of the adoption of the merger agreement and would be payable following certification of the results of the special meeting. The payment of the conditional special dividend is not conditioned on completion of the merger and, if stockholder approval of the adoption of the merger agreement is obtained, will be paid regardless of whether the merger is completed. If stockholder approval of the adoption of the merger agreement is obtained, each holder of any Company RSU Awards or Company DSU Awards outstanding as of the record date of the special meeting, that provide for dividend equivalents, will receive a dividend equivalent in an amount equal to the product of (i) the conditional special dividend, and (ii) the number of shares underlying such Company RSU Award or Company DSU Award in accordance with the terms of such award.

Due to the contingent nature of the conditional special dividend, the NYSE rules require the Company’s common stock to trade with “due bills,” representing an assignment of the right to receive the conditional special dividend, beginning on August 20, 2018 (one business day prior to the record date) through the due bill period. The Company’s common stock will not trade ex-dividend until the first business day after the conditional special dividend payment date (the “ex-dividend date”). This means that purchasers of the Company’s common stock during the due bill period that hold the Company’s common stock on the conditional special dividend payment date are entitled to receive the conditional special dividend in the event stockholder approval of the adoption of the merger agreement is obtained. Stockholders that sell the Company’s common stock during the due bill period are not entitled to receive the conditional special dividend in the event stockholder approval of the adoption of the merger agreement is obtained. Investors who enter into trades to purchase the Company’s common stock on or after the ex-dividend date will not receive the conditional special dividend. The conditional special dividend is

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conditioned on the merger agreement being adopted by our stockholders at the special meeting and, if the merger agreement is so adopted, will be paid following certification of the results of the special meeting.

Due bills obligate sellers who were stockholders of record on the record date to deliver the conditional special dividend, if paid, to the subsequent buyer. Accordingly, holders of the Company’s common stock on the record date must hold the Company’s common stock through the conditional special dividend payment date to be entitled to receive the conditional special dividend. The due bill obligations are settled customarily between the brokers representing the buyers and sellers of the Company’s common stock. The Company has no obligations for either the amount of the due bill or the processing of the due bill. Buyers and sellers of the Company’s common stock during the due bill period should consult their broker before trading in the Company’s common stock to be sure they understand the effect of the NYSE’s due-bill procedures.

The Company will grant a Dividend Make-Whole Amount to each holder of Incentive Equity Awards that were outstanding as of June 10, 2018 in the form of a cash payment in an amount equal to the product of (i) the conditional special dividend, multiplied by (ii) the number of shares of common stock that either (a) are or become vested and paid out on such Incentive Equity Awards in connection with the completion of the merger and did not otherwise participate in the conditional special dividend, or (b) subject to the applicability of due bill trading, are or become vested and become payable following the record date, but prior to the closing date of the merger, in each case as determined by the Company. The Dividend Make-Whole Amount will be earned upon the effective time of the merger subject to the holder of the underlying Incentive Equity Award remaining continuously employed by the Company and its subsidiaries until immediately prior to the effective time of the merger, and will be paid promptly thereafter, but in no event later than 15 days following the effective time of the merger. However, if any holder of outstanding Incentive Equity Awards terminates employment with the Company or any of its subsidiaries prior to the effective time of the merger, and any such Incentive Equity Awards remain outstanding following such termination in accordance with their terms, then such holder will still be eligible to receive a Dividend Make-Whole Amount with respect to such outstanding Incentive Equity Awards.

Representations and Warranties

The merger agreement contains representations and warranties of the Company, subject to certain exceptions in the merger agreement, in the Company disclosure letter delivered in connection with the merger agreement and in the Company’s public filings, as to, among other things:

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The merger agreement also contains representations and warranties of Knauf and Merger Sub, subject to certain exceptions in the merger agreement and Knauf’s disclosure letter delivered in connection with the merger agreement, as to, among other things:

Some of the representations and warranties in the merger agreement are qualified by materiality qualifications or a “material adverse effect” qualification, as discussed below.

For purposes of the merger agreement, a “material adverse effect” means, with respect to the Company, a change, circumstance, condition, event, effect, development or state of facts (each, a “change”) that, individually or in the aggregate, is or would reasonably be expected to be materially adverse to the business, assets, financial condition, operations or results of operations of the Company, and its subsidiaries, taken as a whole. However, none of the following will be deemed, either alone or in combination, to constitute, and none of the following will be taken into account in determining whether there has been, a material adverse effect:

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However, in the case of the first, second, third, ninth, tenth and eleventh bullet points above, any such change may be taken into account to the extent that it has a disproportionate adverse effect on the Company and its subsidiaries, taken as a whole, as compared to other participants in the industries in which the Company and its subsidiaries operate (but, in which case, only the incremental disproportionate impact may be taken into account), and, in the case of the ninth bullet point above, any such change may be taken into account to the extent that it relates primarily only to, or has an effect primarily relating to, the Company and its subsidiaries.

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Conduct of Business Pending the Merger

The merger agreement provides that, from and after the date of the merger agreement until the effective time of the merger, except as required by applicable law, as set forth in the Company’s disclosure letter to the merger agreement, as otherwise expressly provided for in the merger agreement or as Knauf may otherwise consent in writing, the Company will, and will cause its subsidiaries to, conduct its business in all material respects in the ordinary course of business consistent with past practices, and will use its reasonable best efforts to preserve intact its business organization and goodwill and preserve its relationships with governmental authorities, customers, suppliers, business associates, distributors, strategic and joint venture partners and others having business dealings with it, and keep available the services of its employees, and will not and will cause its subsidiaries not to:

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Access

Upon reasonable notice, the Company will, and will cause each of its subsidiaries to, afford Knauf and its representatives reasonable access during normal business hours to the respective properties, books, records (including tax records), contracts, commitments and personnel for the purposes of completing the merger; provided, however, that, prior to the effective time of the merger, Knauf and its affiliates and representatives will not conduct any environmental site assessment or conduct any testing or any sampling of soil, sediment, surface water, ground water or building material at, on or within any property of the Company and its subsidiaries. Further, the Company will not be required to permit any inspection, or to disclose any information, that in the Company’s reasonable judgment would (i) violate applicable law, (ii) waive any protection of an attorney-client privilege or other legal privilege (subject to reasonable cooperation between the parties with respect to entering into appropriate joint defense, community of interest or similar agreement or arrangement with respect to the preservation of such privileges), or (iii) result in the disclosure of any trade secrets of third parties or violate any of its obligations with respect to confidentiality.

Acquisition Proposals

Pursuant to the merger agreement, the Company will, and will cause its subsidiaries and the representatives of the Company and its subsidiaries to, immediately cease and terminate any existing activities, discussions or negotiations with any person or its representatives with respect to any acquisition proposal (as defined below), or any inquiry, proposal or offer that would reasonably be expected to lead to any acquisition proposal, and will discontinue access of such persons and their representatives to any electronic data room or similar information-sharing platform and will request the prompt return or destruction of any confidential information previously furnished or made available to such persons in connection therewith.

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Except as expressly permitted by the merger agreement, from and after June 10, 2018, the Company will not, and will cause each of its subsidiaries to not and will not authorize or knowingly permit any of its representatives to, directly or indirectly:

Pursuant to the merger agreement, an “acquisition proposal” means an inquiry, proposal or offer from, or indication of interest in making a proposal or offer by, any person, whether or not subject to conditions, relating to any transaction or series of transactions involving any direct or indirect:

Notwithstanding certain provisions of the merger agreement described above, at any time prior to, but not after, obtaining stockholder approval of the adoption of the merger agreement, the Company may, in response to

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an unsolicited bona fide written acquisition proposal made after the date of the merger agreement that did not result from a breach of the above conditions, furnish information and data to the person making such acquisition proposal and its representatives pursuant to and in accordance with an acceptable confidentiality agreement and participate and engage in discussions or negotiations with the person regarding such acquisition proposal if and only if, in each case, the Board has determined in good faith, after consultation with its outside legal counsel and financial advisors of nationally recognized reputation, that such acquisition proposal constitutes or could reasonably be expected to lead to a superior proposal (as defined below). All information provided by the Company or its subsidiaries to any person entering into an acceptable confidentiality agreement that has not been previously provided to Knauf must be provided by the Company to Knauf prior to or substantially concurrently with the time it is provided to such person.

Pursuant to the merger agreement, a “superior proposal” means a bona fide written acquisition proposal that has not been withdrawn and that did not result from a breach of the provisions of merger agreement that (i) if completed, would result in any third person (or in the case of a direct merger between such third person and the Company, the stockholders of such third person) acquiring, directly or indirectly, more than 80 percent of the voting power of the outstanding shares of our common stock or all or substantially all of the assets of the Company, (ii) is reasonably capable of being completed, taking into account all financial, legal, regulatory and other aspects of such acquisition proposal, including all conditions contained therein, the nature of the consideration offered, and the identity of the person making such acquisition proposal, and (iii) the Board determines in good faith, after consultation with outside legal counsel and financial advisors of nationally recognized reputation (taking into account the items identified in the foregoing clause (ii) and any changes to the merger agreement proposed by Knauf in response to an acquisition proposal), is more favorable from a financial point of view to the Company’s stockholders than the merger.

Except as described below, the Board will not (i) fail to include its recommendation in the proxy statement, (ii) change, withhold, withdraw or qualify or modify in a manner adverse to Knauf, or propose publicly change, withhold, withdraw or qualify or modify in a manner adverse to Knauf, its recommendation, (iii) approve, adopt, declare advisable, endorse or recommend, or publicly propose to approve, adopt, declare advisable, endorse or recommend, any acquisition proposal, (iv) with respect to any publicly announced bona fide acquisition proposal, fail to confirm publicly through a press release or similar means its recommendation on the earlier of (A) the fifth business day after the date when requested to do so in writing by Knauf and (B) the second business day prior to the special meeting, (v) if a tender or exchange offer for shares of the Company’s common stock is commenced, fail to recommend against acceptance of such tender or exchange offer by the stockholders or the Company on the earlier of (x) the tenth business day after the commencement of such tender or exchange offer pursuant to Rule 14d-2 under the Exchange Act and (y) the second business day prior to the special meeting, or (vi) resolve or propose to take any action described in clause (i) through (v) above (we refer to any of the foregoing actions, as a “change in recommendation”).

Notwithstanding other provisions in the merger agreement, at any time prior to, but not after, obtaining stockholder approval of the adoption of the merger agreement, if a material positive change with respect to the Company and its subsidiaries (an “intervening event”) has occurred and is continuing or the Company has received an acquisition proposal after the date of the merger agreement that has not been withdrawn or otherwise modified and that did not result from a breach of the provisions of the merger agreement that the Board has determined in good faith, after consultation with its outside legal counsel and financial advisors of nationally recognized reputation, constitutes a superior proposal, then (i) the Board may effect a change in recommendation and (ii) the Board may authorize the Company to take any action pursuant to the termination provisions, if and only if the Board has determined in good faith, after consultation with its outside legal counsel and financial advisors of nationally recognized reputation, that the failure to do so would be inconsistent with its fiduciary duties to the Company’s stockholders under Delaware Law.

The Board may not effect a change in recommendation unless (i) the Board has provided at least five business days advance written notice to Knauf that it is prepared to effect a change in recommendation which

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will include a description of the intervening event or the most current version of the superior proposal, including the identity of the person making the superior proposal, as applicable, (ii) during the applicable five business day period, if requested by Knauf, the Company and its representatives have engaged in good faith negotiations with Knauf and considered any binding proposal by Knauf, and (iii) Knauf does not make, within five business days after receipt of such notice, a binding proposal that the Board determines in good faith obviates the need for a change in recommendation or termination of the merger agreement, as applicable.

Notwithstanding any change in recommendation, the Board will continue with its obligations under the merger agreement and will submit the merger agreement to the stockholders of the Company for the purpose of obtaining stockholder approval of the adoption of the merger agreement unless the merger agreement has been terminated prior to the date of the special meeting.

The Special Meeting

As promptly as practicable after the SEC confirms that it has no further comments on this proxy statement (or lapse of the applicable waiting period during which the SEC is permitted to comment on this proxy statement), the Company will (i) set a record date for the special meeting and (ii) call, give notice of, convene and hold the special meeting. The Company will use reasonable best efforts (consistent with the efforts customarily used in transactions of the type contemplated by the merger agreement) to solicit and obtain stockholder approval of the adoption of the merger agreement.

The special meeting will be held regardless of any change in recommendation by the Board, unless the merger agreement is terminated in accordance with provisions of the merger agreement. Unless the merger agreement is terminated in accordance with such provisions, the Company will not postpone or adjourn the special meeting except to the extent (i) Knauf has consented to such postponement or adjournment in writing or (ii) the Company, acting in good faith after consulting with outside legal counsel, determines that (A) such postponement or adjournment is necessary to ensure that any required supplement or amendment to the proxy statement is provided to the Company’s stockholders within a reasonable amount of time in advance of the special meeting, (B) it will not receive proxies sufficient to obtain stockholder approval of the adoption of the merger agreement, whether or not a quorum is present, or it will not have a sufficient number of shares of common stock represented in person or by proxy to constitute a quorum necessary to conduct the business of the special meeting, or (C) such postponement or adjournment is required to comply with applicable law; provided that in the case of a postponement or adjournment in accordance with clause (ii) above, the date of the special meeting will not be postponed or adjourned by more than an aggregate of 15 calendar days without Knauf’s prior written approval.

Financing and Financing Assistance

The merger is not conditioned upon the receipt of financing by Knauf. However, Knauf has agreed that it will use its reasonable best efforts to take all actions and to do all things reasonably necessary to arrange and complete the debt financing (the “debt financing”) on the terms in the debt commitment letter, including using its reasonable best efforts to (i) maintain in effect the debt commitment letter, (ii) satisfy or cause to be satisfied on a timely basis (or, if determined advisable by Knauf, obtain the waiver of) all terms and conditions applicable to Knauf set forth in the debt commitment letter that are within its control, and (iii) negotiate and enter into definitive agreements with respect to the debt financing on the terms and conditions substantially comparable to those contemplated by the debt commitment letter.

The Company will, and will cause its subsidiaries and representatives to, at the expense of Knauf, use its and their reasonable best efforts to provide such cooperation as reasonably requested by Knauf, to assist Knauf in arranging, obtaining or syndicating the debt financing, any alternative financing (which will be on terms that will enable Knauf to complete the merger and that are not less favorable in the aggregate to the Company and its subsidiaries than those contained in the debt commitment letter) or any debt or equity financing undertaken in

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any form in replacement of all or any portion of such debt financing or alternative financing or otherwise for the purposes of financing the closing consideration and the other required payments under the merger agreement.

Employee Matters

The merger agreement provides that Knauf will provide or cause to be provided to each Continuing USG Employee compensation and benefits during the period from the effective time of the merger until December 31 of the calendar year following the calendar year in which the effective time of the merger occurs, on the following terms:

Following the effective time of the merger, Knauf or the surviving corporation will honor all of our employee benefit plans and compensation arrangements and agreements, in accordance with their terms. In addition, Knauf, for purposes of any of its employee benefit plans in which Continuing USG Employees are eligible to participate following the completion of the merger, will recognize for purposes of eligibility, vesting and level of benefits each Continuing USG Employee’s years of service with the Company and its subsidiaries before the effective time of the merger, to the same extent as such employee was entitled, before the effective time of the merger, to credit for such service under any comparable Company benefit plan, unless (i) its application would result in a duplication of benefits, (ii) similarly situated employees of Knauf do not receive credit for such service, (iii) such Company benefit plans did not recognize such period of service or did not provide credit for prior service, or (iv) such Knauf benefit plan is frozen or a grandfathered plan. With respect to medical, dental or vision insurance benefits, for the plan year in which such Continuing USG Employee is first eligible to participate (i) any preexisting conditions or limitations and eligibility waiting periods will be waived with respect to the Continuing USG Employees and their eligible dependents to the extent such limitation would have been waived or satisfied under the Company benefit plan in which such Continuing USG Employee participated immediately prior to the merger, and (ii) the amount of eligible expenses incurred by each Continuing USG Employee and his or her eligible dependents that were credited to deductible and maximum out-of-pocket co-insurance requirements under the Company benefit plans immediately prior to the merger will be credited for purposes of satisfying the deductible and maximum out-of-pocket co-insurance requirements under the corresponding Knauf benefit plans.

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Knauf’s obligations to provide such compensation and benefits to Continuing USG Employees who are covered by a collective bargaining agreement or based outside of the United States will be modified or adjusted as necessary to comply with the terms of such collective bargaining agreement or the laws of such countries in which such Continuing USG Employees are based.

Efforts to Complete the Merger

The Company and Knauf have agreed to cooperate with each other and use their respective reasonable best efforts to take, or cause to be taken, all actions, and to do, or cause to be done, all things necessary, proper or advisable under any applicable law to complete and make effective in the most expeditious manner possible the merger, including (i) determining all necessary filings, notices, petitions, clearances, statements, registrations, submissions of information, applications and other documents to complete the merger, (ii) preparing and filing as promptly as practicable all documentation to effect such filings, notices, petitions, statements, registrations, submissions of information, applications and other documents, (iii) the satisfaction of the conditions to completing the merger, (iv) taking actions necessary to obtain (and to cooperate with each other in obtaining) any consent, authorization, order or approval of, or any exemption by, any governmental authority (which actions will include furnishing all information required under the HSR Act, and other applicable competition laws and foreign investment laws and in connection with (x) obtaining such approvals, authorizations, clearances, consents or exemptions under the HSR Act and such other applicable competition laws and foreign investment laws for the jurisdictions set forth in the merger agreement or (y) filings with any governmental authority) required to be obtained or made by Knauf, Merger Sub, the Company or any of their respective subsidiaries or affiliates in connection with the transactions contemplated by the merger agreement, and (v) the execution and delivery of any additional instruments necessary to completing the transactions contemplated by the merger agreement and to fully carry out the purposes of the merger. Prior to the closing, the Company will use, and will cause its subsidiaries to use, reasonable best efforts to cooperate with Knauf to obtain consents and waivers required from parties to the Company contracts that have not been obtained, except that (A) none of the Company or its subsidiaries will be required to make any payments, incur any liability or obligation, or offer or grant any accommodation (financial or otherwise) to any such third party in connection with obtaining any such consent or waiver and (B) in no event will the failure to obtain any such consent or waiver in and of itself be a condition to any of the obligations of Knauf or the Merger Sub to effect the closing.

Knauf will, and will cause its subsidiaries and affiliates to, take all actions necessary to procure, as promptly as reasonably possible, and in any event no later than January 1, 2019 (the “end date”), any and all approvals, authorizations, clearances, consents or exemptions under the HSR Act and such other applicable competition laws and foreign investment laws (collectively, “antitrust approvals”) that would, if not procured, otherwise have the effect of materially delaying or preventing the completion of the merger, including (i) proposing, negotiating, committing to and effecting, by consent decree, hold separate order, or otherwise, the sale, divestiture or disposition of such businesses, product lines or assets of Knauf and its subsidiaries and affiliates and (ii) otherwise taking or committing to take actions that, after the closing date, would limit Knauf’s or its subsidiaries’ or affiliates’ freedom of action with respect to, or its or their ability to retain, one or more of the businesses, product lines or assets of Knauf and its subsidiaries or affiliates, in each case as may be required in order to avoid the entry of, or to effect the dissolution of, any preliminary or permanent injunction, in any proceeding under the HSR Act or any other applicable competition law or foreign investment law, which would otherwise have the effect of preventing the closing, and in that regard, Knauf will agree to divest, sell, dispose of, hold separate, or otherwise take or commit to take any action that limits its freedom of action with respect to, or Knauf’s or its subsidiaries’ or affiliates’ ability to retain, any of the businesses, product lines or assets of Knauf or any of its subsidiaries or affiliates.

Indemnification and Insurance