Filed Pursuant to Rule 424(b)(3)
Registration No. 333-225761

MERGER PROPOSED—YOUR VOTE IS VERY IMPORTANT

August 3, 2018

Dear Stockholder:

On May 20, 2018, MB Financial, Inc., or MB Financial, entered into an Agreement and Plan of Merger, or the merger agreement, with Fifth Third Bancorp, or Fifth Third, and Fifth Third Financial Corporation, or Intermediary, a wholly-owned subsidiary of Fifth Third. The merger agreement provides for the combination of MB Financial and Fifth Third, either through the merger of MB Financial with and into Intermediary, with Intermediary as the surviving corporation, which we refer to as the direct merger, or through the merger of a newly formed subsidiary of Fifth Third with and into MB Financial, with MB Financial as the surviving corporation, which we refer to as the alternative merger. Only if the direct merger is not approved by the MB Financial preferred stockholders will the alternative merger occur instead of the direct merger, if the applicable common stockholder approvals for the alternative merger and charter amendment described below are obtained. We collectively refer to the direct merger and the alternative merger as the merger.

In the merger, each outstanding share of MB Financial common stock will be converted into the right to receive 1.45 shares of Fifth Third common stock and $5.54 in cash, which we refer to as the merger consideration. Additionally, if the direct merger is approved by the holders of MB Financial’s 6.00% Non-Cumulative Perpetual Preferred Stock, Series C, or MB Financial preferred stock, each share of MB Financial preferred stock will be converted into the right to receive one share of a newly created series of preferred stock of Fifth Third having substantially the same terms as the MB Financial preferred stock, except that the new series of Fifth Third preferred stock will have no voting rights (including upon an arrearage in the payment of dividends) except as required by Ohio law and will have certain other differences consistent with Fifth Third’s currently outstanding series of preferred stock and its articles of incorporation. If the direct merger is not approved by the holders of MB Financial preferred stock, then the alternative merger will occur instead of the direct merger, in which case the holders of MB Financial common stock will receive the same merger consideration as described above, but the MB Financial preferred stock will not be converted into a share of new Fifth Third preferred stock and will instead remain outstanding and unchanged (except as modified by the proposed charter amendment referred to below) as preferred stock of MB Financial, which will be a subsidiary of Fifth Third.

Based on the closing price of Fifth Third common stock on the NASDAQ Global Select Market, or NASDAQ, on May 18, 2018, the last trading day before public announcement of the merger agreement, the value of the per share merger consideration payable to holders of MB Financial common stock would be $54.20. Based on the closing price of Fifth Third common stock on the NASDAQ on August 1, 2018, the last practicable trading date before the date of this proxy statement/prospectus, the value of the per share merger consideration payable to holders of MB Financial common stock would be $48.72. Based on the number of shares of MB Financial common stock outstanding and the number of shares of MB Financial common stock issuable pursuant to outstanding MB Financial stock options, restricted stock awards, restricted stock units and performance awards, in each case as of August 1, 2018, the total number of shares of Fifth Third common stock expected to be issued in connection with the merger is approximately 127,245,626. In addition, based on the number of issued and outstanding shares of Fifth Third common stock and MB Financial common stock on August 1, 2018, and based on the exchange ratio of 1.45, holders of MB Financial common stock immediately prior to the closing of the merger will hold, in the aggregate, approximately 16% of the issued and outstanding shares of Fifth Third common stock immediately following the closing of the merger (without giving effect to any shares of Fifth Third common stock held by MB Financial stockholders prior to the merger). Based on the number of shares of MB Financial preferred stock and the number of depositary shares, each representing a 1/40^th interest in a share of MB Financial preferred stock, outstanding as of August 1, 2018, the total number of shares of new Fifth Third preferred stock expected to be issued in connection with the merger is 200,000 and the total number of depositary shares expected to be issued in respect of the new Fifth Third preferred stock is 8,000,000. The depositary shares issued in respect of the new Fifth Third preferred stock are expected to be listed on the NASDAQ Global Select Market. As indicated above, if the alternative merger occurs instead of the direct merger, the MB Financial preferred stock will remain outstanding and no new Fifth Third preferred stock will be issued.

MB Financial will hold a special meeting of its stockholders at which the holders of MB Financial preferred stock will be asked to approve the direct merger, and the holders of MB Financial common stock will be asked to approve the merger (whether effected as the direct merger or, in the event the MB Financial preferred stockholders fail to approve the direct merger, as the alternative merger) and an amendment to MB Financial’s charter and articles supplementary for the MB Financial preferred stock, which we refer to as the charter amendment, that would give the holders of MB Financial preferred stock the right to vote with the holders of MB Financial common stock as a single class on all matters submitted to a vote of such common stockholders, effective immediately prior to the consummation of the alternative merger, and

related matters. The special meeting will be held on September 18, 2018, at 8:30 a.m., local time, at MB Financial Center, 6111 North River Road, Rosemont, Illinois 60018.

The direct merger cannot be completed unless the MB Financial common stockholders and MB Financial preferred stockholders approve the direct merger. The alternative merger cannot be completed unless MB Financial common stockholders approve the alternative merger and, if the MB Financial preferred stockholders fail to approve the direct merger, the charter amendment. Only if the direct merger is not approved by the MB Financial preferred stockholders will the alternative merger occur instead of the direct merger, if the applicable common stockholder approvals for the alternative merger are obtained. Therefore, it is essential that MB Financial common stockholders approve both the merger (which will constitute approval of both the direct merger and the alternative merger) and the charter amendment to ensure the merger can be completed in the event the MB Financial preferred stockholders fail to approve the direct merger.

Computershare Inc. and Computershare Trust Company N.A., which we refer to collectively as the depositary, holds of record all of the outstanding shares of MB Financial preferred stock on behalf of the holders of depositary shares, each representing a 1/40^th interest in a share of MB Financial preferred stock. The depositary is required to vote the MB Financial preferred stock in accordance with the instructions of the holders of the depositary shares. Where we refer to holders of MB Financial preferred stock, this includes holders of depositary shares representing interests in MB Financial preferred stock unless the context indicates otherwise.

YOUR VOTE IS VERY IMPORTANT, REGARDLESS OF THE NUMBER OF SHARES OR DEPOSITARY SHARES YOU OWN. To ensure your representation at the special meeting, please complete and return the enclosed proxy card or submit your proxy by following the instructions contained in this proxy statement/prospectus and on your proxy card. Please vote promptly whether or not you expect to attend the special meeting. If you hold your shares or depositary shares in “street name,” you should instruct your broker, bank or other nominee how to vote in accordance with the voting instruction form you receive from your broker, bank or other nominee.

The MB Financial Board of Directors has unanimously approved the merger agreement and the transactions contemplated thereby and recommends that holders of MB Financial preferred stock vote “FOR” the direct merger and that holders of MB Financial common stock vote “FOR” the merger, “FOR” the charter amendment and “FOR” a proposal to approve, on a non-binding advisory basis, the compensation to be paid to MB Financial’s named executive officers that is based on or otherwise relates to the merger, discussed in the accompanying proxy statement/prospectus under the section entitled “The Merger—Interests of MB Financial Directors and Executive Officers in the Merger” beginning on page 70.

This proxy statement/prospectus provides you with detailed information about the proposed transaction. It also contains or references information about Fifth Third and MB Financial and certain related matters. You are encouraged to read this proxy statement/prospectus carefully. In particular, you should read the “Risk Factors” section beginning on page 27 for a discussion of the risks you should consider in evaluating the proposed transaction and how it may affect you.

If you have any questions regarding the accompanying proxy statement/prospectus, you may contact D.F. King, MB Financial’s proxy solicitor, by calling toll-free at (800) 431-9645.

Sincerely,

Mitchell Feiger

President and Chief Executive Officer

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of the merger, the charter amendment, the issuance of Fifth Third common shares or the new Fifth Third preferred stock in connection with the merger or the other transactions described in this proxy statement/prospectus, or passed upon the adequacy or accuracy of the disclosure in this proxy statement/prospectus. Any representation to the contrary is a criminal offense.

The securities to be issued in connection with the merger are not savings accounts, deposits or other obligations of any bank or savings association and are not insured by the Federal Deposit Insurance Corporation or any other governmental agency.

This proxy statement/prospectus is dated August 3, 2018, and is first being mailed to stockholders of MB Financial on or about August 3, 2018.

WHERE YOU CAN FIND MORE INFORMATION

Both Fifth Third and MB Financial file annual, quarterly and special reports, proxy statements and other business and financial information with the Securities and Exchange Commission (the “SEC”). You may read and copy any materials that either Fifth Third or MB Financial files with the SEC at the SEC’s Public Reference Room at 100 F Street, N.E., Room 1580, Washington, D.C. 20549, at prescribed rates. Please call the SEC at (800) SEC-0330 ((800) 732-0330) for further information on the public reference room. In addition, Fifth Third and MB Financial file reports and other business and financial information with the SEC electronically, and the SEC maintains a website located at www.sec.gov containing this information. You will also be able to obtain these documents, free of charge, from Fifth Third at ir.53.com under “SEC Filings,” or from MB Financial by accessing MB Financial’s website at investor.mbfinancial.com under the “Financial Information” tab and under the heading “SEC Filings.”

Fifth Third has filed a registration statement on Form S-4 of which this proxy statement/prospectus forms a part. As permitted by SEC rules, this proxy statement/prospectus does not contain all of the information included in the registration statement or in the exhibits or schedules to the registration statement. You may obtain a free copy of the registration statement, including any amendments, schedules and exhibits at the addresses set forth below. Statements contained in this proxy statement/prospectus as to the contents of any contract or other documents referred to in this proxy statement/prospectus are not necessarily complete. In each case, you should refer to the copy of the applicable contract or other document filed as an exhibit to the registration statement. This proxy statement/prospectus incorporates by reference documents that Fifth Third and MB Financial have previously filed with the SEC. These documents contain important information about the companies and their financial condition. See “Incorporation of Certain Documents by Reference” beginning on page 133. These documents are available without charge to you upon written or oral request to the applicable company’s principal executive offices. The respective addresses and telephone numbers of such principal executive offices are listed below. 

To obtain timely delivery of these documents, you must request the information no later than September 11, 2018 in order to receive them before the special meeting of stockholders.

Fifth Third common shares are traded on the Nasdaq Global Select Market under the symbol “FITB,” MB Financial common stock is traded on the Nasdaq Global Select Market under the symbol “MBFI” and the depositary shares, each representing a 1/40^th interest in a share of MB Financial preferred stock, are traded on the Nasdaq Global Select Market under the symbol “MBFIO.”

NOTICE OF SPECIAL MEETING OF STOCKHOLDERS TO BE HELD ON SEPTEMBER 18, 2018

NOTICE IS HEREBY GIVEN that a special meeting of stockholders of MB Financial, Inc. (which we refer to as “MB Financial”) will be held on September 18, 2018, at 8:30 a.m. local time, at MB Financial Center, 6111 North River Road, Rosemont, Illinois 60018, for the following purposes:

The affirmative vote of the holders of at least two-thirds of the outstanding shares of MB Financial preferred stock, voting as a separate class from the MB Financial common stock, is required to approve the preferred stockholder merger proposal.

The affirmative vote of the holders of a majority of the outstanding shares of MB Financial common stock entitled to vote thereon, voting as a separate class from the MB Financial preferred stock, is required to approve each of the common stockholder merger proposal and the charter amendment proposal. The affirmative vote of a majority of the votes cast by the holders of MB Financial common stock is required to approve, on a non-binding, advisory basis, the merger-related compensation proposal and the common stockholder adjournment proposal. The affirmative vote of a majority of the votes cast by the holders of MB Financial preferred stock is required to approve the preferred stockholder adjournment proposal.

MB Financial will transact no other business at the special meeting except for business properly brought before the special meeting or any adjournment or postponement thereof.

The merger cannot be completed unless MB Financial common stockholders approve the common stockholder merger proposal and, if the MB Financial preferred stockholders fail to approve the preferred stockholder merger proposal, the charter amendment proposal. Therefore, it is essential that MB Financial common stockholders approve both the common stockholder merger proposal and the charter amendment proposal to ensure the merger can be completed in the event the MB Financial preferred stockholders fail to approve the preferred stockholder merger proposal. The MB Financial preferred stockholders are not entitled to vote on the charter amendment proposal or the merger-related compensation proposal. The voting by MB Financial common stockholders on the merger-related compensation proposal is advisory only and will have no effect on the separate votes cast on the common stockholder merger proposal or the charter amendment proposal. Approval of the charter amendment proposal is necessary to obtain required tax opinions in the event the alternative merger will occur instead of the direct merger. The proxy statement/prospectus accompanying this notice explains the merger agreement and the transactions contemplated thereby, as well as the proposals to be considered at the special meeting. Please review the proxy statement/prospectus carefully.

The MB Financial Board of Directors has set August 1, 2018 as the record date for the special meeting. Only holders of record of MB Financial common stock and MB Financial preferred stock at the close of business on August 1, 2018 will be entitled to notice of and to vote at the special meeting and any adjournments or postponements thereof.

Computershare Inc. and Computershare Trust Company N.A., which we refer to collectively as the depositary, holds of record all of the outstanding shares of MB Financial preferred stock on behalf of the holders of depositary shares, each representing a 1/40^th interest in a share of MB Financial preferred stock. The depositary is required to vote the MB Financial preferred stock in accordance with the instructions of the holders of the depositary shares. Where we refer to “holders of MB Financial preferred stock” or “MB Financial preferred stockholders,” this includes holders of the depositary shares representing interests in the MB Financial preferred stock unless the context indicates otherwise.

YOUR VOTE IS VERY IMPORTANT, REGARDLESS OF THE NUMBER OF SHARES OR DEPOSITARY SHARES YOU OWN. Whether or not you plan to attend the special meeting, please complete, sign, date and mail the enclosed proxy card in the postage-paid envelope provided as soon as possible. You may also submit a proxy by telephone or via the Internet by following the instructions printed on your proxy card. If you hold your shares or depositary shares through a broker, bank or other nominee, you should direct the voting of your shares or depositary shares in accordance with the voting instruction form received from your broker, bank or other nominee.

The MB Financial Board of Directors has unanimously approved the merger agreement and the transactions contemplated thereby and recommends that holders of MB Financial common stock vote “FOR” the common stockholder merger proposal, “FOR” the charter amendment proposal, “FOR” the merger-related compensation proposal and “FOR” the common stockholder adjournment proposal (if necessary or appropriate), and recommends that holders of MB Financial preferred stock vote “FOR” the preferred stockholder merger proposal and “FOR” the preferred stockholder adjournment proposal (if necessary or appropriate).

If you have any questions or need assistance with voting, please contact our proxy solicitor, D.F. King, toll-free at (800) 431-9645.

Record holders of MB Financial common stock may vote in person at the special meeting by filling out a ballot or may use a proxy authorizing the designated proxies to vote on his, her or its behalf. The depositary will vote the shares of MB Financial preferred stock in accordance with the instructions it receives from holders of depositary shares representing interests in the MB Financial preferred stock.

If you hold shares of MB Financial common stock through a broker, bank or other nominee and wish to vote your shares in person at the special meeting, then you must obtain a legal proxy from the holder of record authorizing you to do so by contacting your broker, bank or other nominee. MB Financial reserves the right to limit admission to the special meeting to stockholders of record and persons holding shares of common stock or depositary shares through a broker, bank or other nominee who provide appropriate documentation of beneficial ownership, such as a recent brokerage account statement.

By Order of the Board of Directors

Mitchell Feiger

President and Chief Executive Officer

Chicago, Illinois

August 3, 2018

TABLE OF CONTENTS

QUESTIONS AND ANSWERS ABOUT THE MERGER AND THE SPECIAL MEETING

The following are answers to certain questions that you may have regarding the merger and the special meeting. We urge you to read carefully the remainder of this proxy statement/prospectus because the information in this section may not provide all the information that might be important to you in determining how to vote. Additional important information is also contained in the appendices to, and the documents incorporated by reference in, this proxy statement/prospectus.

MB Financial will hold a special meeting of its stockholders to obtain the required stockholder approvals, and you are being provided with this proxy statement/prospectus in connection with that meeting. A copy of the merger agreement is attached to this proxy statement/prospectus as Appendix A. We urge you to read carefully this proxy statement/prospectus and the merger agreement in their entirety.

This document constitutes both a proxy statement of MB Financial and a prospectus of Fifth Third. It is a proxy statement because the Board of Directors of MB Financial is soliciting proxies using this document from MB Financial stockholders. It is a prospectus because Fifth Third is offering (i) in connection with the merger, shares of its common stock in partial exchange for the outstanding shares of MB Financial common stock and (ii) in connection with the direct merger, its newly-created series of preferred stock designated 6.00% Non-Cumulative Perpetual Preferred Stock, Series K (which we refer to as the “new Fifth Third preferred stock”), and depositary shares in respect thereof, in exchange for the outstanding shares of MB Financial’s 6.00% Non-Cumulative Perpetual Preferred Stock, Series C (which we refer to as the “MB Financial preferred stock”), and depositary shares in respect thereof. The new Fifth Third preferred stock will have substantially the same terms as the MB Financial preferred stock, except that the new Fifth Third preferred stock will have no voting rights (including upon an arrearage in the payment of dividends) except as required by Ohio law and will have certain other differences consistent with Fifth Third’s currently outstanding series of preferred stock and its articles of incorporation.

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Although the merger consideration is fixed, the value of the stock portion of the merger consideration will fluctuate between the date of this proxy statement/prospectus and the completion of the merger based upon the market value of Fifth Third common stock. Any fluctuation in the market price of Fifth Third common stock after the date of this proxy statement/prospectus will change the value of the shares of Fifth Third common stock that MB Financial common stockholders will receive in the merger.

If the merger is completed as the alternative merger, which will be the case if the direct merger is not approved by the holders of MB Financial preferred stock and the alternative merger and charter amendment are approved by the holders of MB Financial common stock, the MB Financial preferred stock will not be converted into a share of new Fifth Third preferred stock and will instead remain outstanding and unchanged (except as modified by the proposed charter amendment referred to below) as preferred stock of MB Financial, which will be a subsidiary of Fifth Third. Approval of the common stockholder merger proposal described below under “What are MB Financial stockholders being asked to vote on?” constitutes approval of both the direct merger and the alternative merger by the holders of MB Financial common stock.

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Computershare Inc. and Computershare Trust Company N.A. (which we refer to collectively as the “depositary”), holds of record all of the outstanding shares of MB Financial preferred stock on behalf of the holders of depositary shares, each representing a 1/40^th interest in a share of MB Financial preferred stock. The depositary is required to vote the MB Financial preferred stock in accordance with the instructions of the holders of the depositary shares. Where we refer to “holders of MB Financial preferred stock” or “MB Financial preferred stockholders,” this includes holders of the depositary shares representing interests in MB Financial preferred stock unless the context indicates otherwise.

Holders of MB Financial common stock are being asked to vote on the following proposals:

The merger cannot be completed unless MB Financial common stockholders approve the common stockholder merger proposal and, if the MB Financial preferred stockholders fail to approve the preferred stockholder merger proposal, the charter amendment proposal. Therefore, it is essential that MB Financial common stockholders approve both the common stockholder merger proposal and the charter amendment proposal to ensure the merger can be completed in the event the MB Financial preferred stockholders fail to approve the preferred stockholder merger proposal.

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Upon completion of the alternative merger, MB Financial will be a subsidiary of Fifth Third, who will control MB Financial. MB Financial preferred stockholders will vote with Fifth Third as a single class on all matters submitted to a vote of Fifth Third, as the sole common stockholder of MB Financial following completion of the alternative merger. Thus, the voting rights that would be conferred upon the MB Financial preferred stockholders by the charter amendment would continue to apply with respect to MB Financial, and not Fifth Third, following completion of the alternative merger.

Common Stockholder Merger Proposal: The affirmative vote of the holders of a majority of the outstanding shares of MB Financial common stock as of the record date and entitled to vote thereon is required to approve the common stockholder merger proposal.

Charter Amendment Proposal: The affirmative vote of the holders of a majority of the outstanding shares of MB Financial common stock as of the record date and entitled to vote thereon is required to approve the charter amendment proposal.

Merger-Related Compensation Proposal: The affirmative vote of a majority of the votes cast by the holders of MB Financial common stock on the merger-related compensation proposal is required to approve the merger-related compensation proposal. The merger-related compensation proposal is an advisory vote, and therefore is not binding on MB Financial or on Fifth Third or the Boards of Directors or the compensation committees of MB Financial or Fifth Third. Since compensation and benefits to be paid or provided in connection with the merger are based on contractual arrangements with the named executive officers, the outcome of this advisory vote will not affect the obligation to make these payments. MB Financial is seeking this non-binding advisory stockholder approval pursuant to the Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010 and Rule 14a-21(c) under the Securities Exchange Act of 1934, as amended (which we refer to as the “Exchange Act”), which requires MB Financial to provide its common stockholders with the opportunity to vote to approve, on a non-binding, advisory basis, the compensation that may be paid or become payable to MB Financial’s named executive officers in connection with the

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merger. The merger-related compensation proposal gives MB Financial common stockholders the opportunity to express their views on the merger-related compensation of MB Financial’s named executive officers. MB Financial’s common stockholders are not required to approve the merger-related compensation proposal in order for the merger to occur. If MB Financial’s common stockholders fail to approve the merger-related compensation proposal, but approve the common stockholder merger proposal and, in the event the MB Financial preferred stockholders fail to approve the preferred stockholder merger proposal, the charter amendment proposal, the merger may nonetheless occur.

Preferred Stockholder Adjournment Proposal: The affirmative vote of a majority of the votes cast by the holders of MB Financial preferred stock on the preferred stockholder adjournment proposal is required to approve the preferred stockholder adjournment proposal.

Common Stockholder Adjournment Proposal: The affirmative vote of a majority of the votes cast by the holders of MB Financial common stock on the common stockholder adjournment proposal is required to approve the common stockholder adjournment proposal.

If you are a holder of record of MB Financial common stock as of the record date, you may also cast your vote in person at the special meeting. While holders of depositary shares representing MB Financial preferred stock may attend the special meeting, they may not vote such depositary shares in person at the special meeting; such depositary shares may only be voted by providing voting instructions to the depositary, and the depositary will vote the shares of MB Financial preferred stock represented thereby in accordance with such instructions.

If your shares or depositary shares are held in “street name” through a broker, bank or other nominee, your broker, bank or other nominee will send you separate instructions describing the procedure for voting your shares or depositary shares. Please refer to the voting instruction form for the applicable deadline for voting your shares or depositary shares. Holders of MB Financial common stock in “street name” who wish to vote in person at the special meeting will need to obtain a proxy form from their broker, bank or other nominee.

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Unless so revoked, the shares and depositary shares represented by such proxies and voting instructions will be voted at the special meeting and all adjournments or postponements of the special meeting.

The obligation of Fifth Third and MB Financial to complete the merger is conditioned upon the receipt of legal opinions from their respective counsel to the effect that the merger will qualify as a reorganization within the meaning of Section 368(a) of the Internal Revenue Code.

If the merger qualifies as a reorganization for United States federal income tax purposes, (1) U.S. holders of MB Financial common stock who receive a combination of Fifth Third common shares and cash, other than cash instead of a fractional Fifth Third common share, in exchange for their MB Financial common stock, will recognize gain (but not loss) in an amount equal to the lesser of (x) the amount by which the sum of the fair market value of the Fifth Third common shares and cash (other than cash received instead of a fractional Fifth Third common share) received by such holder in exchange for its shares of MB Financial common stock exceeds the holder’s adjusted basis in its shares of MB Financial common stock, and (y) the amount of cash (other than cash received instead of fractional Fifth Third common shares) received by such holder in exchange for its shares of MB Financial common stock; and (2) U.S. holders of MB Financial preferred stock who either receive solely new Fifth Third preferred stock in the merger or who will not convert their shares into Fifth Third preferred stock pursuant to the alternative merger and will remain holders of MB Financial preferred stock (including the receipt of voting rights prior to the alternative merger) will not recognize any gain or loss. Generally, any gain recognized upon the exchange will be capital gain, and any such capital gain will be long-term capital gain if the holding period for such shares of MB Financial common stock is more than one year. Depending on certain facts specific to you, gain could instead be characterized as ordinary dividend income.

For a more detailed discussion of the material United States federal income tax consequences of the transaction, see “Material United States Federal Income Tax Consequences of the Merger” beginning on page 99.

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The consequences of such merger to any particular stockholder will depend on that stockholder’s particular facts and circumstances. Accordingly, you are urged to consult your tax advisor to determine your tax consequences from the merger.

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CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

This proxy statement/prospectus contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 including, but not limited to, Fifth Third’s and MB Financial’s expectations or predictions of future financial or business performance or conditions. Forward-looking statements are typically identified by words such as “believe,” “expect,” “anticipate,” “intend,” “target,” “estimate,” “continue,” “positions,” “plan,” “predict,” “project,” “forecast,” “guidance,” “goal,” “objective,” “prospects,” “possible” or “potential,” by future conditional verbs such as “assume,” “will,” “would,” “should,” “could” or “may”, or by variations of such words or by similar expressions. These forward-looking statements are subject to numerous assumptions, risks and uncertainties, which change over time. Forward-looking statements speak only as of the date they are made and we assume no duty to update forward-looking statements. Actual results may differ materially from current projections.

In addition to factors previously disclosed in Fifth Third’s and MB Financial’s reports filed with the SEC and those identified elsewhere in this filing (including the “Risk Factors” beginning on page 27), the following factors among others, could cause actual results to differ materially from forward-looking statements or historical performance:

For any forward-looking statements made in this proxy statement/prospectus or in any documents incorporated by reference into this proxy statement/prospectus, Fifth Third and MB Financial claim the protection of the safe

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harbor for forward-looking statements contained in the Private Securities Litigation Reform Act of 1995. You are cautioned not to place undue reliance on these statements, which speak only as of the date of this proxy statement/prospectus or the date of the applicable document incorporated by reference in this proxy statement/prospectus. Except to the extent required by applicable law, Fifth Third and MB Financial do not undertake to update forward-looking statements to reflect facts, circumstances, assumptions or events that occur after the dates on which the forward-looking statements are made. All written and oral forward-looking statements concerning the merger or other matters addressed in this proxy statement/prospectus and attributable to Fifth Third, MB Financial or any person acting on their behalf are expressly qualified in their entirety by the cautionary statements contained or referred to in this proxy statement/prospectus.

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RISK FACTORS

In addition to the other information contained in or incorporated by reference into this proxy statement/prospectus, including the matters addressed under the caption “Forward-Looking Statements,” you should carefully consider the following risk factors in deciding how to vote on the proposals presented in this proxy statement/prospectus. See “Where You Can Find More Information” in the forepart of this proxy statement/prospectus and “Incorporation of Certain Documents by Reference” beginning on page 133.

Risks Related to the Merger

Because the Market Price of Fifth Third Common Shares Will Fluctuate, MB Financial Common Stockholders Cannot Be Sure of the Value of the Merger Consideration They Will Receive.

Upon completion of the merger, each share of MB Financial common stock will be converted into the per share merger consideration consisting of Fifth Third common shares and cash pursuant to the terms of the merger agreement. The stock portion of the merger consideration that MB Financial stockholders will receive is a fixed number of Fifth Third common shares; it is not a number of shares with a particular fixed market value. See “The Merger—Terms of the Merger” beginning on page 46. The market value of Fifth Third common shares and MB Financial common stock at the effective time of the merger may vary significantly from their respective values on the date the merger agreement was executed or at other dates, including the date on which MB Financial stockholders vote on the approvals needed for the merger. Because the exchange ratio relating to the stock portion of the merger consideration is fixed at 1.45 and will not be adjusted to reflect any changes in the market value of Fifth Third common shares or MB Financial common stock, the market value of the Fifth Third common shares issued in connection with the merger and the MB Financial common stock converted in connection with the merger may be higher or lower than the values of those shares on earlier dates, and may be higher or lower than the value used to determine the exchange ratio. Accordingly, at the time of the special meeting, MB Financial common stockholders will not know or be able to calculate the market value of the Fifth Third common shares they would receive upon the completion of the merger. Stock price changes may result from a variety of factors, including changes in the business, operations or prospects of Fifth Third or MB Financial, regulatory considerations, and general business, market, industry or economic conditions. Many of these factors are outside of the control of Fifth Third and MB Financial.

MB Financial Common Stockholders Will Have a Reduced Ownership and Voting Interest After the Merger and Will Exercise Less Influence Over Management.

MB Financial common stockholders currently have the right to vote in the election of the MB Financial Board of Directors and on other matters requiring stockholder approval under Maryland law and MB Financial’s charter and bylaws. Upon the completion of the merger, each MB Financial common stockholder will become a stockholder of Fifth Third with a percentage ownership of Fifth Third that is smaller than such stockholder’s percentage ownership of MB Financial. Additionally, only two out of the expected fourteen members of the Fifth Third Board of Directors at the effective time of the merger will be appointed by MB Financial upon the completion of the merger. Based on the number of issued and outstanding Fifth Third common shares and shares of MB Financial common stock on August 1, 2018, and based on the exchange ratio of 1.45, the common stockholders of MB Financial, as a group, will receive shares in the merger constituting approximately 16% of Fifth Third common shares expected to be outstanding immediately after the merger (without giving effect to any Fifth Third common shares held by MB Financial common stockholders prior to the merger). Because of this, current MB Financial common stockholders, as a group, will have less influence on the Board of Directors, management and policies of Fifth Third (as the combined company following the merger) than they now have on the Board of Directors, management and policies of MB Financial.

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The Market Price of Fifth Third Common Shares After the Merger May be Affected by Factors Different from Those Currently Affecting the Prices of Fifth Third Common Shares and MB Financial Common Stock.

Upon completion of the merger, holders of MB Financial common stock will become holders of Fifth Third common shares. Fifth Third’s businesses differ from those of MB Financial, and accordingly the results of operations of Fifth Third will be affected by some factors that are different from those currently affecting the results of operations of MB Financial. For example, Fifth Third operates in certain states of the United States, including Florida, Georgia, Kentucky, Michigan, North Carolina, Ohio, Tennessee and West Virginia, where MB Financial does not have significant operations. Accordingly, the results of operations of Fifth Third will be affected by business and other developments in those areas of the country to a larger extent than those of MB Financial. See “Where You Can Find More Information” in the forepart of this proxy statement/prospectus and “Incorporation of Certain Documents by Reference” beginning on page 133.

Fifth Third May Fail to Realize the Anticipated Benefits of the Merger.

Fifth Third and MB Financial have operated and, until the completion of the merger, will continue to operate, independently. The success of the merger, including anticipated benefits and cost savings, will depend on, among other things, Fifth Third’s ability to combine the businesses of Fifth Third and MB Financial in a manner that permits growth opportunities, including, among other things, enhanced revenues and revenue synergies, an expanded market reach and operating efficiencies, and does not materially disrupt the existing customer relationships of Fifth Third or MB Financial or result in decreased revenues due to any loss of customers. If Fifth Third is not able to successfully achieve these objectives, the anticipated benefits of the merger may not be realized fully or at all or may take longer to realize than expected. Failure to achieve these anticipated benefits could result in increased costs, decreases in the amount of expected revenues and diversion of management’s time and energy and could have an adverse effect on the combined company’s business, financial condition, operating results and prospects.

Certain employees may not be employed by Fifth Third after the merger. In addition, employees that Fifth Third wishes to retain may elect to terminate their employment as a result of the merger, which could delay or disrupt the integration process. It is possible that the integration process could result in the disruption of Fifth Third’s or MB Financial’s ongoing businesses or cause inconsistencies in standards, controls, procedures and policies that adversely affect the ability of Fifth Third or MB Financial to maintain relationships with customers and employees or to achieve the anticipated benefits of the merger.

Among the factors considered by the Boards of Directors of Fifth Third and MB Financial in connection with their respective approvals of the merger agreement were the benefits that could result from the merger. There can be no assurance that these benefits will be realized within the time periods contemplated or at all.

Regulatory Approvals May Not Be Received, May Take Longer than Expected or May Impose Conditions that Are Not Presently Anticipated or Cannot Be Met.

Before the transactions contemplated in the merger agreement can be completed, various approvals must be obtained from the bank regulatory and other governmental authorities. In deciding whether to grant these approvals, the relevant governmental entities will consider a variety of factors, including the regulatory standing of each of the parties and the effect of the merger on competition. An adverse development in either party’s regulatory standing or other factors could result in an inability to obtain one or more of the required regulatory approvals or delay receipt of required approvals. The Federal Reserve Board has stated that if supervisory issues arise during processing of an application for approval of a merger transaction, a banking organization will be expected to withdraw its application pending resolution of such supervisory concerns. Accordingly, if there is an adverse development in either party’s regulatory standing, Fifth Third may be required to withdraw its application for approval of the proposed merger and, if possible, resubmit it after the applicable supervisory concerns have been resolved.

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The terms of the approvals that are granted may impose conditions, limitations, obligations or costs, or place restrictions on the conduct of the combined company’s business or require changes to the terms of the transactions contemplated by the merger agreement. There can be no assurance that regulators will not impose any such conditions, limitations, obligations or restrictions and that such conditions, limitations, obligations or restrictions will not have the effect of delaying the completion of any of the transactions contemplated by the merger agreement, imposing additional material costs on or materially limiting the revenues of the combined company following the merger or otherwise reduce the anticipated benefits of the merger if the merger were consummated successfully within the expected timeframe. Nor can there be any assurance that any such conditions, terms, obligations or restrictions will not result in the delay or abandonment of the merger. Additionally, the completion of the merger is conditioned on the absence of certain orders, injunctions or decrees by any court or regulatory agency of competent jurisdiction that would prohibit or make illegal the completion of any of the transactions contemplated by the merger agreement.

Fifth Third and MB Financial believe that the proposed transactions should not raise significant regulatory concerns and that Fifth Third will be able to obtain all requisite regulatory approvals in a timely manner. However, the processing time for obtaining regulatory approvals for mergers of banking institutions, particularly for larger institutions, has increased since the financial crisis. In addition, despite the parties’ commitments to use their reasonable best efforts to comply with conditions imposed by regulatory entities, under the terms of the merger agreement, Fifth Third and MB Financial will not be required to take actions that would reasonably be expected to have a material adverse effect on Fifth Third and its subsidiaries, taken as a whole, after giving effect to the merger (measured on a scale relative to MB Financial and its subsidiaries, taken as a whole).

The Merger Agreement May Be Terminated in Accordance with Its Terms and the Merger May Not Be Completed.

The merger agreement is subject to a number of conditions which must be fulfilled in order to complete the merger. Those conditions include: approval of the merger and charter amendment by the MB Financial common stockholders, receipt of requisite regulatory approvals, absence of orders prohibiting completion of any of the proposed transactions, effectiveness of the registration statement of which this proxy statement/prospectus is a part, approval of the Fifth Third common shares to be issued in connection with the merger for listing on the NASDAQ, the accuracy of the representations and warranties by both parties (subject to the materiality standards set forth in the merger agreement) and the performance by both parties of their covenants and agreements, and the receipt by both parties of legal opinions from their respective tax counsels. These conditions to the closing of the merger may not be fulfilled in a timely manner or at all, and, accordingly, the merger may not be completed. In addition, the parties can mutually decide to terminate the merger agreement at any time, before or after stockholder approval, or Fifth Third or MB Financial may elect to terminate the merger agreement in certain other circumstances.

Termination of the Merger Agreement Could Negatively Impact MB Financial.

If the merger is not completed for any reason, including as a result of MB Financial stockholders declining to approve the MB Financial stockholder matters, the ongoing business of MB Financial may be adversely impacted and, without realizing any of the anticipated benefits of completing the merger, MB Financial would be subject to a number of risks, including the following:

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If the merger agreement is terminated and MB Financial’s Board of Directors seeks another merger or business combination, MB Financial stockholders cannot be certain that MB Financial will be able to find a party willing to offer equivalent or more attractive consideration than the consideration Fifth Third has agreed to provide in the merger, or that such other merger or business combination will be completed. If the merger agreement is terminated under certain circumstances, MB Financial may be required to pay a termination fee of $151.2 million to Fifth Third. See “The Merger Agreement—Termination; Termination Fee” on page 96.

MB Financial Will Be Subject to Business Uncertainties and Contractual Restrictions While the Merger Is Pending.

Uncertainty about the effect of the merger on employees and customers may have an adverse effect on MB Financial and consequently on Fifth Third. These uncertainties may impair MB Financial’s ability to attract, retain and motivate key personnel until the merger is completed, and could cause customers and others that deal with MB Financial to seek to change existing business relationships with MB Financial. Retention of certain employees may be challenging during the pendency of the merger, as certain employees may experience uncertainty about their future roles. If key employees depart because of issues relating to the uncertainty or difficulty of integration or a desire not to remain with the business, Fifth Third’s business following the merger could be negatively impacted. In addition, the merger agreement restricts MB Financial from making certain acquisitions and taking other specified actions without the consent of Fifth Third until the merger occurs. These restrictions may prevent MB Financial from pursuing attractive business opportunities that may arise prior to the completion of the merger. See “The Merger Agreement—Covenants and Agreements—Conduct of Business Prior to the Completion of the Merger” beginning on page 86.

MB Financial Directors and Officers May Have Interests in the Merger Different From the Interests of MB Financial Stockholders.

The interests of some of the directors and executive officers of MB Financial may be different from those of MB Financial stockholders, and directors and officers of MB Financial may be participants in arrangements that are different from, or are in addition to, those of MB Financial stockholders. See “The Merger—Interests of MB Financial Directors and Executive Officers in the Merger” beginning on page 70.

The Merger Agreement Contains Provisions that May Discourage Other Companies from Trying to Acquire MB Financial for Greater Merger Consideration.

The merger agreement contains provisions that may discourage a third party from submitting a business combination proposal to MB Financial that might result in greater value to MB Financial’s stockholders than the merger or may result in a potential competing acquirer proposing to pay a lower per share price to acquire MB Financial than it might otherwise have proposed to pay absent such provisions. These provisions include a general prohibition on MB Financial from soliciting, or, subject to certain exceptions relating to the exercise of fiduciary duties by MB Financial’s Board of Directors, entering into discussions with any third party regarding

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any acquisition proposal or offers for competing transactions. MB Financial also has an unqualified obligation to submit the proposal to approve the merger to a vote by its stockholders, even if MB Financial receives an alternative acquisition proposal that its Board of Directors believes is superior to the merger, unless the merger agreement has been terminated in accordance with its terms. In addition, MB Financial may be required to pay Fifth Third a termination fee of $151.2 million upon termination of the merger agreement in certain circumstances involving acquisition proposals for competing transactions. See “The Merger Agreement—Termination; Termination Fee” beginning on page 96.

The Opinion of MB Financial’s Financial Advisor Delivered to the MB Financial Board of Directors Prior to the Signing of the Merger Agreement Will Not Reflect Changes in Circumstances Following the Date of the Opinion.

The opinion from MB Financial’s financial advisor was delivered on and dated May 20, 2018. Changes in the operations and prospects of MB Financial or Fifth Third, general market and economic conditions and other factors that may be beyond the control of MB Financial or Fifth Third may significantly alter the value of MB Financial or the prices of the Fifth Third common shares or shares of MB Financial common stock by the time the merger is completed. The opinion does not speak as of the time the merger will be completed or as of any date other than the date of such opinion. See “The Merger—Opinion of MB Financial’s Financial Advisor” beginning on page 59.

Fifth Third and MB Financial Will Incur Transaction and Integration Costs in Connection with the Merger.

Each of Fifth Third and MB Financial has incurred and expects that it will incur significant, non-recurring costs in connection with consummating the merger. In addition, Fifth Third will incur integration costs following the completion of the merger as Fifth Third integrates the businesses of the two companies, including facilities and systems consolidation costs and employment-related costs. There can be no assurances that the expected benefits and efficiencies related to the integration of the businesses will be realized to offset these transaction and integration costs over time. See the risk factor entitled “—Fifth Third May Fail to Realize the Anticipated Benefits of the Merger” above. Fifth Third and MB Financial may also incur additional costs to maintain employee morale and to retain key employees. Fifth Third and MB Financial will also incur significant legal, financial advisor, accounting, banking and consulting fees, fees relating to regulatory filings and notices, SEC filing fees, printing and mailing fees and other costs associated with the merger. Some of these costs are payable regardless of whether the merger is completed.

MB Financial Stockholders Will Become Stockholders of an Ohio Corporation and Will Have Their Rights As Stockholders Governed by Fifth Third’s Organizational Documents and Ohio Law.

Upon completion of the merger, holders of shares of MB Financial common stock, MB Financial stock options, MB Financial restricted stock awards, MB Financial restricted stock unit awards, MB Financial performance share unit awards and MB Financial preferred stock will become holders of Fifth Third common shares, Fifth Third stock options, Fifth Third restricted stock awards or Fifth Third restricted stock unit awards and, solely in the case of the direct merger, new Fifth Third preferred stock, which will be governed by Fifth Third’s organizational documents and the Ohio General Corporation Law. As a result, there will be differences between the rights currently enjoyed by MB Financial stockholders and the rights they expect to have as stockholders of the combined company. See “Comparison of Stockholders’ Rights” beginning on page 104.

Potential Litigation Against MB Financial and Fifth Third Could Result in an Injunction Preventing the Completion of the Merger or a Judgment Resulting in the Payment of Damages.

Stockholders of MB Financial may file lawsuits against Fifth Third, MB Financial and/or the directors and officers of either company in connection with the merger. These lawsuits could prevent or delay the completion of the merger and result in significant costs to MB Financial and/or Fifth Third, including any costs associated

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with the indemnification of directors and officers. The defense or settlement of any lawsuit or claim that remains unresolved at the time the merger is completed may adversely affect Fifth Third’s business, financial condition, results of operations and cash flows.

Additional Risks Relating to the New Fifth Third Preferred Stock or MB Financial Preferred Stock

Fifth Third’s Creditworthiness May Affect the Market Value of the New Fifth Third Preferred Stock.

The value of the new Fifth Third preferred stock if the direct merger is completed will be affected, among other things, by Fifth Third’s general creditworthiness. For a discussion and analysis of known material trends and events, and risks or uncertainties that are reasonably expected to have a material effect on Fifth Third’s business, financial condition or results of operations, you should review the Fifth Third documents incorporated by reference into this proxy statement/prospectus. See “Incorporation of Certain Documents by Reference” beginning on page 133.

Changes in Credit Ratings May Affect the Market Value of the New Fifth Third Preferred Stock.

If the direct merger is completed, real or anticipated changes in credit ratings on Fifth Third or the new Fifth Third preferred stock may affect the market value of the new Fifth Third preferred stock. In addition, real or anticipated changes in credit ratings can affect the cost at which Fifth Third can transact or obtain funding, and thereby affect Fifth Third’s liquidity, business, financial condition or results of operations.

In the Event of Fifth Third’s Insolvency, the New Fifth Third Preferred Stock Will Rank Junior to Other Securities.

In the event of Fifth Third’s insolvency, any new Fifth Third preferred stock issued in the direct merger and outstanding will rank equally with certain of Fifth Third’s other outstanding series of preferred stock. If Fifth Third becomes insolvent or is wound up, its assets must be used to pay its deposit liabilities and other debt, including subordinated debt, before payments may be made on Fifth Third’s preferred stock, including the new Fifth Third preferred stock. See “Description of Fifth Third Capital Stock” beginning on page 118.

Yields on Similar Securities Will Likely Affect the Market Value of the New Fifth Third Preferred Stock.

Prevailing yields on securities similar to the new Fifth Third preferred stock will likely affect the market value of the new Fifth Third preferred stock. Assuming all other factors remain unchanged, the market value of the new Fifth Third preferred stock will likely decline as prevailing yields for similar securities rise, and will likely increase as prevailing yields for similar securities decline.

An active trading market for the new Fifth Third preferred stock (or related depositary shares) does not exist and may not develop and the market price and liquidity of the depositary shares may be adversely affected.

The new Fifth Third preferred stock (or related depositary shares), if issuable, are new issues of securities with no established trading market. Fifth Third will use its reasonable best efforts to cause the new Fifth Third preferred stock (or related depositary shares) to be approved for listing on the NASDAQ. However, Fifth Third cannot be certain that the new Fifth Third preferred stock (or related depositary shares) will qualify for listing. If they do not qualify for listing, or if an active trading market does not develop, holders of new Fifth Third preferred stock may have difficulty selling any of the new Fifth Third preferred stock (or related depositary shares). Fifth Third cannot predict the extent to which investor interest in the new Fifth Third preferred stock (or related depositary shares) will lead to the development of an active trading market on the NASDAQ or how liquid that market might become. If an active, liquid market does not develop for the new Fifth Third preferred stock (or related depositary shares), the market price and liquidity of the depositary shares may be adversely affected.

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If the alternative merger is effected, the price for MB Financial preferred stock that remains outstanding may be depressed.

If the alternative merger is effected, then the MB Financial preferred stock will remain outstanding after consummation of the alternative merger. However, Fifth Third currently expects to delist the MB Financial preferred stock from the NASDAQ and terminate MB Financial’s registration and reporting obligations with the SEC so that at or promptly following the closing of the alternative merger, the MB Financial preferred stock will no longer trade on the NASDAQ or any other securities exchange. Additionally, MB Financial will no longer file reports or other public disclosure with the SEC. As a result, these actions may have a significant and adverse effect on the liquidity of, and the price of, the MB Financial preferred stock and may result in the MB Financial preferred stock being less liquid for an indefinite period of time.

If the alternative merger is effected, the outstanding shares of MB Financial preferred stock will vote with Fifth Third, as the sole holder of MB Financial common stock, on all matters submitted to a vote of the common stockholders of MB Financial.

Upon completion of the alternative merger, MB Financial will be a subsidiary of Fifth Third, who will control MB Financial. MB Financial preferred stockholders will vote with Fifth Third as a single class on all matters submitted to a vote of Fifth Third, as the sole common stockholder of MB Financial following completion of the alternative merger. Thus, the voting rights that would be conferred upon the MB Financial preferred stockholders by the charter amendment would continue to apply with respect to MB Financial, and not Fifth Third, following completion of the alternative merger.

Risks Relating to the Tax Consequences of the Merger

If the merger does not constitute a reorganization under Section 368(a) of the Internal Revenue Code, then MB Financial stockholders may be responsible for payment of U.S. income taxes related to the consideration they receive in the merger.

The United States Internal Revenue Service (“IRS”) may determine that the merger does not qualify as a tax-free reorganization under Section 368(a) of the Internal Revenue Code of 1986, as amended (the “Code”). In that case, each MB Financial stockholder would recognize a gain or loss equal to the difference between the sum of any cash consideration and the fair market value of the Fifth Third common shares or Fifth Third preferred stock, as applicable, received by the stockholder in the merger, and such stockholder’s adjusted tax basis in the shares of MB Financial common stock or MB Financial preferred stock exchanged therefor.

The alternative merger’s qualification as a tax-free reorganization is dependent on the market price of Fifth Third common shares and if the market price of Fifth Third common shares declines significantly the merger agreement may be terminated or the alternative merger may not constitute a tax-free reorganization.

The merger agreement is subject to a number of conditions which must be fulfilled in order to complete the merger. One of those conditions includes the receipt by both parties of legal opinions from their respective tax counsels that the alternative merger constitutes a tax-free reorganization. The qualification of the alternative merger as a tax-free reorganization under Section 368(a)(2)(E) of the Internal Revenue Code depends on the application of numerous technical requirements, including whether MB Financial stockholders will receive a sufficient amount of Fifth Third common shares to satisfy the “control” test applicable to the alternative merger. For purposes of Section 368(a)(2)(E) of the Internal Revenue Code, “control” is defined by Section 368(c) as ownership of stock possessing at least 80 percent of the total combined voting power of all classes of stock entitled to vote and at least 80 percent of the total number of shares of all other classes of stock of the corporation. Satisfaction of the control test will depend on the value, as of the closing of the alternative merger, of the Fifth Third common shares received by holders of MB Financial common stock in exchange for MB Financial common stock relative to the value of the consideration other than Fifth Third common shares received by holders of MB Financial common stock in exchange for shares of MB Financial common stock in connection with the alternative merger.

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Due to uncertainty surrounding the market price of Fifth Third common shares immediately prior to the closing, if the market price of Fifth Third common shares declines, neither Fifth Third nor MB Financial can assure you that they will be able to obtain legal opinions from their respective tax counsels that the alternative merger constitutes a tax-free reorganization under Section 368(a)(2)(E). Therefore, the legal opinion condition to the closing of the alternative merger may not be fulfilled in a timely manner or at all, and, accordingly, the alternative merger may not be completed.

Further, even if Fifth Third and MB Financial later determine to take the position that the alternative merger qualifies as a tax-free reorganization, neither Fifth Third nor MB Financial can assure you that the IRS will accept the treatment of the alternative merger as a reorganization. If the IRS were to challenge such treatment and successfully contend that the alternative merger failed to qualify as a reorganization, the alternative merger would be a fully taxable transaction to MB Financial stockholders.

Additional Risks Relating to Fifth Third and MB Financial After the Merger

Fifth Third’s and MB Financial’s businesses are, and will continue to be, subject to the risks described in (i) Part I, Item 1A in Fifth Third’s Annual Report on Form 10-K for the fiscal year ended December 31, 2017 and (ii) Part I, Item 1A in MB Financial’s Annual Report on Form 10-K for the fiscal year ended December 31, 2017, in each case, as such risks may be updated or supplemented in each company’s subsequent Quarterly Reports on Form 10-Q or Current Reports on Form 8-K filed with the SEC and incorporated by reference in this proxy statement/prospectus. See “Incorporation of Certain Documents by Reference” beginning on page 133.

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MB FINANCIAL SPECIAL MEETING OF STOCKHOLDERS

Date, Time and Place of the Special Meeting

The special meeting of MB Financial stockholders will be held on September 18, 2018, at 8:30 a.m. local time, at MB Financial Center, 6111 North River Road, Rosemont, Illinois 60018. On or about August 3, 2018, this proxy statement/prospectus was mailed to holders of MB Financial common stock and MB Financial preferred stock entitled to vote at the special meeting.

Purpose of the Special Meeting

The special meeting is being held for the following purposes:

Recommendation of the MB Financial Board of Directors

The MB Financial Board of Directors recommends that holders of MB Financial common stock vote “FOR” the common stockholder merger proposal, “FOR” the charter amendment proposal, “FOR” the merger-related compensation proposal and “FOR” the common stockholder adjournment proposal (if necessary or appropriate), and recommends that holders of MB Financial preferred stock vote “FOR” the preferred stockholder merger proposal and “FOR” the preferred stockholder adjournment proposal (if necessary or appropriate). See “The Merger—Recommendation of the MB Financial Board of Directors and Reasons for the Merger” beginning on page 54.

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Record Date and Quorum

The MB Financial Board of Directors has fixed the close of business on August 1, 2018 as the record date for determining the holders of MB Financial common stock and the holders of MB Financial preferred stock entitled to receive notice of and to vote at the special meeting.

As of the record date, there were 84,420,704 shares of MB Financial common stock outstanding and entitled to vote at the MB Financial special meeting held by 1,366 holders of record. Each share of MB Financial common stock entitles the holder thereof as of the record date to one vote at the special meeting on each proposal to be considered at the special meeting by the common stockholders, provided, however, that pursuant to Section F of Article 5 of MB Financial’s charter, no person who beneficially owns more than 14.9% of the shares of MB Financial common stock outstanding as of the record date may vote shares in excess of this limit.

As of the record date, there were 200,000 shares of MB Financial preferred stock outstanding, all of which were held by Computershare Inc. and Computershare Trust Company N.A. (which we refer to collectively as the “depositary”), on behalf of the holders of depositary shares each representing a 1/40^th interest in a share of MB Financial preferred stock. Under the terms of the deposit agreement among MB Financial, the depositary and the holders from time to time of the depositary receipts evidencing the depositary shares, the depositary is required to vote the MB Financial preferred stock in accordance with the instructions of the holders of the depositary shares. Where we refer to “holders of MB Financial preferred stock” or “MB Financial preferred stockholders,” this includes holders of the depositary shares unless the context indicates otherwise.

The holders of a majority of the outstanding shares of MB Financial common stock, present in person or represented by proxy, will constitute a quorum for purposes of the matters being voted upon by the common stockholders. The holders of a majority of the outstanding shares of MB Financial preferred stock, present in person or represented by proxy, will constitute a quorum for purposes of the matters being voted upon by the preferred stockholders.

As of the record date, the directors and executive officers of MB Financial and their affiliates beneficially owned and were entitled to vote 1,866,405 shares of MB Financial common stock, representing approximately 2.2% of the shares of MB Financial common stock outstanding on that date. MB Financial currently expects that its directors and executive officers will vote their shares of MB Financial common stock in favor of the common stockholder merger proposal, the charter amendment proposal, the merger-related compensation proposal and the common stockholder adjournment proposal (if necessary or appropriate), although none of them has entered into any agreements obligating them to do so. As of the record date, none of the directors and executive officers of MB Financial and their affiliates beneficially owned any depositary shares representing interests in MB Financial preferred stock. As of the record date, excluding shares held in a fiduciary or agency capacity, neither Fifth Third nor any of its directors and executive officers and their affiliates beneficially owned any shares of MB Financial common stock or depositary shares representing interests in MB Financial preferred stock.

Required Vote

Preferred Stockholder Merger Proposal

The affirmative vote of the holders of at least two-thirds of the outstanding shares of MB Financial preferred stock as of the record date is required to approve the preferred stockholder merger proposal.

Common Stockholder Merger Proposal

The affirmative vote of the holders of a majority of the outstanding shares of MB Financial common stock as of the record date and entitled to vote thereon is required to approve the common stockholder merger proposal.

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Charter Amendment Proposal

The affirmative vote of the holders of a majority of the outstanding shares of MB Financial common stock as of the record date and entitled to vote thereon is required to approve the charter amendment proposal.

Merger-Related Compensation Proposal

The affirmative vote of a majority of the votes cast by the holders of MB Financial common stock on the merger-related compensation proposal is required to approve the merger-related compensation proposal.

Common Stockholder Adjournment Proposal

The affirmative vote of a majority of the votes cast by the holders of MB Financial common stock on the common stockholder adjournment proposal is required to approve the common stockholder adjournment proposal.

Preferred Stockholder Adjournment Proposal

The affirmative vote of a majority of the votes cast by the holders of MB Financial preferred stock is required to approve the preferred stockholder adjournment proposal.

Treatment of Abstentions; Failure to Vote

For purposes of the special meeting, an abstention occurs when an MB Financial stockholder attends the MB Financial special meeting, either in person or by proxy, but abstains from voting.

Proxies and Voting Instructions; Incomplete Proxies and Voting Instructions

If you are a holder of record of shares of MB Financial common stock, you may authorize the persons named in the enclosed proxy card to vote your shares of MB Financial common stock at the special meeting in the manner you direct. You may also use one of the following voting methods:

MB Financial requests that you vote by telephone, over the Internet or by completing and signing the accompanying proxy card and returning it as soon as possible in the enclosed postage-paid envelope.

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When a properly executed proxy card is returned by a holder of record of MB Financial common stock prior to the special meeting, the shares of MB Financial common stock represented by the proxy card will be voted at the special meeting in accordance with the instructions contained on the proxy card. If any properly executed proxy card is returned by a holder of record of MB Financial common stock without indication as to how to vote, the shares of MB Financial common stock represented by the proxy card will be voted as recommended by the MB Financial Board of Directors.

If you hold shares of MB Financial common stock or depositary shares representing interests in MB Financial preferred stock in “street name” through a broker, bank or other nominee, you should check the voting instruction form provided to you by that firm to determine whether you may vote by telephone or the Internet. Please refer to the voting instruction form for the applicable deadline for voting your shares or depositary shares.

YOUR VOTE IS VERY IMPORTANT, REGARDLESS OF THE NUMBER OF SHARES OR DEPOSITARY SHARES YOU OWN. PLEASE VOTE, USING ONE OF THE AVAILABLE METHODS, AS SOON AS POSSIBLE.

Shares Held in Street Name

If you hold shares of MB Financial common stock, or depositary shares representing interests in MB Financial preferred stock, in “street name” through a broker, bank or other holder of record, you must provide the record holder of your shares or depositary shares with instructions on how to vote your shares or depositary shares. Please follow the voting instructions provided by the broker or bank. You may not vote shares held in street name by returning a proxy card directly to MB Financial or by voting in person at the special meeting unless you provide a “legal proxy,” which you must obtain from your broker, bank or other nominee. Further, brokers, banks or other nominees who hold shares of MB Financial stock on behalf of their customers may not give a proxy to MB Financial to vote those shares with respect to any of the proposals without specific instructions from their customers, as brokers, banks and other nominees do not have discretionary voting power on these matters. Therefore, if you hold shares of MB Financial common stock, or depositary shares representing interests in MB Financial preferred stock, in street name and do not instruct your broker, bank or other nominee on how to vote your shares or depositary shares, your broker, bank or other nominee will not vote your shares or depositary shares on any proposal on which you are entitled to vote. In the case of the preferred stockholder merger proposal, the common stockholder merger proposal or the charter amendment proposal, this will have the same effect as a vote cast “AGAINST” the proposal. In the case of the merger-related compensation proposal, the common stockholder adjournment proposal or the preferred stockholder adjournment proposal, this will have no effect on the proposal.

Shares Held Through MB Financial 401(k) Profit Sharing Plan

If you hold shares of MB Financial common stock through the MB Financial 401(k) profit sharing plan, you are entitled to instruct the plan trustee on how to vote the shares allocated to your plan account. Plan shares for which voting instructions are not received, or are not timely received, by the plan trustee will be voted in the same proportion as the shares for which timely voting instructions are received by the plan trustee. Refer to the voting instructions form for your plan shares for additional information, including the deadline for submitting your voting instructions.

Revocability of Proxies/Voting Instructions and Changes to a Vote

If you are a holder of record of MB Financial common stock and have submitted your proxy and would like to revoke your proxy, you may do so before your shares are voted at the special meeting by: (i) filing a notice with the Corporate Secretary of MB Financial revoking your proxy, (ii) filing a new, subsequently dated proxy card (whether by proxy card online or by telephone) or (iii) by attending the special meeting and voting your shares in person. Your presence at the special meeting alone will not revoke your proxy. If you have instructed a broker,

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bank or other nominee to vote your shares or depositary shares, you must follow the directions you receive from your broker, bank or other nominee in order to change or revoke your vote.

Unless so revoked, the shares and depositary shares represented by such proxies and voting instructions will be voted at the special meeting and all adjournments or postponements of the special meeting.

Solicitation of Proxies and Voting Instructions

The cost of solicitation of proxies and voting instructions for the special meeting will be borne by MB Financial. MB Financial will reimburse brokerage firms and other custodians, nominees and fiduciaries for reasonable expenses incurred by them in sending materials to the beneficial owners of common stock and depositary shares. MB Financial has retained D.F. King to assist in the solicitation of proxies and voting instructions for a fee of approximately $10,000 plus related fees for any additional services and reasonable out-of-pocket expenses. In addition to solicitations by mail, MB Financial’s directors, officers and regular employees may solicit proxies and voting instructions personally or by telephone without additional compensation.

Attending the Special Meeting

All holders of MB Financial common stock and depositary shares representing interests in MB Financial preferred stock as of the record date, or their duly appointed proxies, may attend the special meeting.

If your shares of MB Financial common stock or depositary shares representing interests in MB Financial preferred stock are held in “street name” in a stock brokerage account or by a bank or nominee and you wish to attend the special meeting, please bring evidence of your beneficial ownership of your shares or depositary shares (e.g., a copy of a recent brokerage statement showing the shares or depositary shares) and valid photo identification with you to the special meeting. If you intend to vote shares of MB Financial common stock in person at the special meeting and you own your shares in street name, you also are required to bring to the special meeting a legal proxy from your broker, bank or other intermediary. While holders of depositary shares representing interests in MB Financial preferred stock may attend the special meeting, they may not vote such depositary shares in person at the special meeting; such depositary shares may only be voted by providing voting instructions to the depositary, and the depositary will vote the shares of MB Financial preferred stock represented thereby in accordance with such instructions.

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MB FINANCIAL PROPOSALS

Preferred Stockholder Merger Proposal, Common Stockholder Merger Proposal and Charter Amendment Proposal

General. As discussed elsewhere in this proxy statement/prospectus, the holders of MB Financial preferred stock will consider and vote on a proposal, which we have defined as the preferred stockholder merger proposal, to approve the direct merger, which we have defined as the merger of MB Financial with and into Intermediary, a wholly-owned subsidiary of Fifth Third, with Intermediary surviving the direct merger. The holders of MB Financial common stock will separately vote on a proposal, which we have defined as the common stockholder merger proposal, to approve the merger, whether effected as the direct merger or as the alternative merger. We have defined the alternative merger as the merger of a newly-formed subsidiary of Fifth Third with and into MB Financial, with MB Financial surviving that merger. Only if the direct merger is not approved by the MB Financial preferred stockholders will the alternative merger occur instead of the direct merger, if the applicable common stockholder approvals for the alternative merger and the charter amendment described below are obtained. The holders of MB Financial common stock will separately vote on a proposal, which we have defined as the charter amendment proposal, to approve the charter amendment, which we have defined as an amendment to the charter of MB Financial and the articles supplementary to the charter of MB Financial relating to the MB Financial preferred stock that would give the holders of MB Financial preferred stock the right to vote with the holders of MB Financial common stock as a single class on all matters submitted to a vote of such common stockholders, to become effective immediately prior to completion of the alternative merger in the event the holders of MB Financial preferred stock do not approve the preferred stockholder merger proposal.

For the preferred stockholder merger proposal, holders of MB Financial preferred stock may vote “FOR,” “AGAINST” or “ABSTAIN,” and for each of the common stockholder merger proposal and the charter amendment proposal, holders of MB Financial common stock may vote FOR,” “AGAINST” or “ABSTAIN.” An abstention or failure to vote on these proposals will have the same effect as a vote cast “AGAINST” such proposals. If you hold depositary shares representing interests in MB Financial preferred stock or shares of MB Financial through a broker, bank or other nominee and you do not instruct your broker, bank or other nominee on how to vote your depositary shares or shares on the these proposals, as applicable, your broker, bank or other nominee will not vote your depositary shares or shares on the applicable proposal, which will have the same effect as a vote cast “AGAINST” such proposal.

The MB Financial Board of Directors recommends that holders of MB Financial preferred stock vote “FOR” the preferred stockholder merger proposal and that holders of MB Financial common stock vote “FOR” the common stockholder merger proposal and “FOR” the charter amendment proposal.

The merger cannot be completed unless MB Financial common stockholders approve the common stockholder merger proposal and, if the MB Financial preferred stockholders fail to approve the preferred stockholder merger proposal, the charter amendment proposal. Therefore, it is essential that MB Financial common stockholders approve both the common stockholder merger proposal and the charter amendment proposal to ensure the merger can be completed in the event the MB Financial preferred stockholders fail to approve the preferred stockholder merger proposal.

Charter Amendment. As indicated above, the charter amendment would amend the charter of MB Financial (specifically, Section C of Article 5 of the charter) and the articles supplementary to the charter of MB Financial relating to the MB Financial preferred stock (specifically, Sections 6(a) and 6(d) of Annex A to the articles supplementary) to give the holders of MB Financial preferred stock the right to vote with the holders of MB Financial common stock as a single class on all matters submitted to a vote of such common stockholders, with the holders of MB Financial preferred stock being entitled to 24 votes for each share of MB Financial preferred stock. If approved by the MB Financial common stockholders, the charter amendment will not become effective until immediately prior to completion of the alternative merger, following the filing of articles of amendment

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with the Department of Assessments and Taxation of the State of Maryland. As noted above, the alternative merger will occur instead of the direct merger if and only if the MB Financial preferred stockholders fail to approve the preferred stockholder merger proposal.

Upon completion of the alternative merger, MB Financial will be a subsidiary of Fifth Third, who will control MB Financial. MB Financial preferred stockholders will vote with Fifth Third as a single class on all matters submitted to a vote of Fifth Third, as the sole common stockholder of MB Financial following completion of the alternative merger. Thus, the voting rights that would be conferred upon the MB Financial preferred stockholders by the charter amendment would continue to apply with respect to MB Financial, and not Fifth Third, following completion of the alternative merger. Approval of the charter amendment proposal is necessary to obtain required tax opinions in the event the alternative merger will occur instead of the direct merger. See “Material United States Federal Income Tax Consequences of the Merger” beginning on page 99.

The text of the proposed charter amendment is set forth in Appendix C to this proxy statement/prospectus. The above description of the charter amendment is qualified in its entirety by reference to the text of the proposed charter amendment.

Merger-Related Compensation Proposal

Pursuant to the Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010 and Rule 14a-21(c) under the Exchange Act, MB Financial is seeking non-binding, advisory approval from the holders of MB Financial common stock of the compensation of MB Financial’s named executive officers that is based on or otherwise relates to the merger as disclosed in “The Merger—Merger-Related Compensation for MB Financial’s Named Executive Officers” beginning on page 75. The proposal gives holders of MB Financial common stock the opportunity to express their views on the merger-related compensation of MB Financial’s named executive officers. Accordingly, MB Financial is requesting holders of MB Financial common stock to adopt the following resolution, on a non-binding, advisory basis:

“RESOLVED, that the compensation that may be paid or become payable to MB Financial’s named executive officers, in connection with the merger, and the agreements or understandings pursuant to which such compensation may be paid or become payable, in each case as disclosed pursuant to Item 402(t) of Regulation S-K in “The Merger—Merger-Related Compensation for MB Financial’s Named Executive Officers,” are hereby APPROVED.”

The vote on this proposal is a vote separate and apart from the votes of the common stockholders to approve the common stockholder merger proposal and the charter amendment proposal. Accordingly, a holder of MB Financial common stock may vote not to approve this proposal on merger-related compensation and benefits to be paid or provided to named executive officers of MB Financial and vote to approve the common stockholder merger proposal and the charter amendment proposal and vice versa. The vote is advisory in nature and, therefore, is not binding on MB Financial or on Fifth Third or the Boards of Directors or the compensation committees of MB Financial or Fifth Third, regardless of whether the other proposals are approved. Approval of the non-binding, advisory proposal with respect to the compensation that may be received by MB Financial’s named executive officers in connection with the merger is not a condition to completion of the merger, and failure to approve this advisory matter will have no effect on the votes of the common stockholders to approve the common stockholder merger proposal or the charter amendment proposal. The merger-related compensation to be paid to named executive officers in connection with the merger is based on contractual arrangements with the named executive officers and, accordingly, the outcome of this advisory vote will not affect the obligation to make these payments.

For the merger-related compensation proposal, holders of MB Financial common stock may vote “FOR,” “AGAINST” or “ABSTAIN.” Holders of MB Financial preferred stock are not entitled to vote on this proposal. If you hold shares of MB Financial common stock and your shares are not present at the special meeting, it will

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have no effect on the merger-related compensation proposal (assuming a quorum is present). If you abstain, your abstention will have no effect on the merger-related compensation proposal, although it will be counted toward establishing a quorum. If you hold shares of MB Financial common stock through a broker, bank or other nominee and you do not instruct your broker, bank or other nominee on how to vote your shares on the merger-related compensation proposal, your broker, bank or other nominee will not vote your shares on the merger-related compensation proposal, which will have no effect on the vote count for such proposal.

The MB Financial Board of Directors recommends that holders of MB Financial common stock vote “FOR” the merger-related compensation proposal.

Preferred Stockholder Adjournment Proposal and Common Stockholder Adjournment Proposal

The special meeting may be adjourned to another time or place, if necessary or appropriate, to permit further solicitation of proxies from the holders of MB Financial preferred stock in favor of the preferred stockholder merger proposal or from the holders of MB Financial common stock in favor of the common stockholder merger proposal and/or the charter amendment proposal.

If, at the special meeting, the number of shares of MB Financial preferred stock present in person or represented by proxy and voting in favor of the preferred stockholder merger proposal is insufficient to approve the preferred stockholder merger proposal, MB Financial may move to adjourn the special meeting in order to enable the MB Financial Board of Directors to solicit additional proxies for the approval of the preferred stockholder merger proposal. Likewise, if the number of shares of MB Financial common stock present in person or represented by proxy and voting in favor of the common stockholder merger proposal and/or the charter amendment proposal is insufficient to approve the common stockholder merger proposal and/or the charter amendment proposal, MB Financial may move to adjourn the special meeting in order to enable the MB Financial Board of Directors to solicit additional proxies for the approval of the common stockholder merger proposal and/or the charter amendment proposal.

In the preferred stockholder adjournment proposal, MB Financial is asking its preferred stockholders to authorize the holder of any proxy solicited by the MB Financial Board of Directors to vote in favor of granting discretionary authority to the proxy holders, and each of them individually, to adjourn the special meeting to another time and/or place for the purpose of soliciting additional proxies from the holders of MB Financial preferred stock for approval of the preferred stockholder merger proposal. In the common stockholder adjournment proposal, MB Financial is asking its common stockholders to authorize the holder of any proxy solicited by the MB Financial Board of Directors to vote in favor of granting discretionary authority to the proxy holders, and each of them individually, to adjourn the special meeting to another time and/or place for the purpose of soliciting additional proxies from the holders of MB Financial common stock for approval of the common stockholder merger proposal and/or the charter amendment proposal. If the preferred stockholder adjournment proposal is approved and/or the common stockholder adjournment proposal is approved, MB Financial could adjourn the special meeting and any adjourned session of the special meeting and use the additional time to solicit additional proxies from the preferred stockholders and/or the common stockholders, as the case may be, including the solicitation of proxies from stockholders who have previously voted. MB Financial does not intend to call a vote on adjournment of the special meeting to solicit additional proxies if the common stockholder merger proposal is approved at the special meeting and either the preferred stockholder merger proposal is approved at the special meeting or the charter amendment proposal is approved at the special meeting. Pursuant to the merger agreement, MB Financial is required to adjourn or postpone the special meeting to solicit additional proxies if it has not received proxies representing a sufficient number of votes for the stockholder approvals needed to complete the merger.

For the preferred stockholder adjournment proposal and the common stockholder adjournment proposal, holders of MB Financial preferred stock and MB Financial common stock may vote “FOR,” “AGAINST” or “ABSTAIN.” Shares not present in person or by proxy at the special meeting will have no effect on the preferred

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stockholder adjournment proposal or the common stockholder adjournment (assuming a quorum is present). An abstention will have no effect on the preferred stockholder adjournment proposal or the common stockholder adjournment proposal, although it will be counted toward establishing a quorum. If you hold depositary shares or shares through a broker, bank or other nominee and you do not instruct your broker, bank or other nominee on how to vote your depositary shares or shares on the preferred stockholder adjournment proposal or the common stockholder adjournment proposal, your broker, bank or other nominee will not vote your depositary shares or shares on the applicable adjournment proposal, which will have no effect on the vote count for such proposal.

The MB Financial Board of Directors unanimously recommends that MB Financial preferred stockholders vote “FOR” the preferred stockholder adjournment proposal (if necessary or appropriate) and that MB Financial common stockholders vote “FOR” the common stockholder adjournment proposal (if necessary or appropriate).

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INFORMATION ABOUT THE COMPANIES

Fifth Third

38 Fountain Square Plaza

Cincinnati, Ohio 45263

Phone: (800) 972-3030

Fifth Third Bancorp is an Ohio business corporation that is registered as a bank holding company under the Bank Holding Company Act of 1956, as amended, and has elected to be treated as a financial holding company under the Gramm-Leach-Bliley Act of 1999 and regulations of the Board of Governors of the Federal Reserve System. Fifth Third was organized in 1975. As of March 31, 2018 Fifth Third had consolidated total assets of $142 billion and total deposits of $105.5 billion. Fifth Third and its subsidiaries had 18,125 full-time equivalent employees as of December 31, 2017.

Fifth Third is the parent holding company for Fifth Third Bank, its principal subsidiary, through which most of its banking services are provided. Through Fifth Third Bank and certain other subsidiaries, Fifth Third provides a wide range of services, including checking, savings and money market accounts, wealth management solutions, payments and commerce solutions, insurance services and credit products such as commercial loans and leases, mortgage loans, credit cards, installment loans, and auto loans to individual, corporate, and institutional clients. Fifth Third serves individuals and businesses through its commercial banking, branch banking, consumer lending, and wealth & asset management businesses. These products and services are provided through 1,153 full-service banking centers and 2,469 Fifth Third-branded ATMs located throughout ten states: Florida, Georgia, Illinois, Indiana, Kentucky, Michigan, North Carolina, Ohio, Tennessee and West Virginia.

Fifth Third Financial Corporation

38 Fountain Square Plaza

Cincinnati, Ohio 45263

Phone: (800) 972-3030

Intermediary is an Ohio corporation and a wholly-owned subsidiary of Fifth Third. Intermediary was incorporated in 2001 and serves as the intermediary holding company for all of Fifth Third’s subsidiaries, including Fifth Third Bank, its principal subsidiary.

MB Financial, Inc.

800 West Madison Street

Chicago, Illinois 60607

Phone: (888) 422-6562

MB Financial is a Maryland corporation and a financial holding company and a bank holding company under the Bank Holding Company Act of 1956, as amended. Its primary market is the Chicago metropolitan area, in which it operates 86 banking offices through its bank subsidiary, MB Financial Bank. Through MB Financial Bank, MB Financial offers a broad range of financial services, primarily to small and middle market businesses and individuals in the markets that it serves. As of March 31, 2018, on a consolidated basis, MB Financial had total assets of $20.2 billion, total deposits of $15.0 billion, stockholders’ equity of $2.9 billion, and client assets under management or advisement of $8.2 billion in its wealth management group (including $3.1 billion in its trust department and $5.1 billion in its bank-owned investment management firm, MSA Holdings, LLC, the parent company of its registered investment advisors, MainStreet Investment Advisors, LLC and Cedar Hill Associates LLC).

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MB Financial’s business segments currently consist of banking, leasing and mortgage banking. Lines of business within the banking segment include commercial banking, loans to leasing companies, retail banking, cards and bank sponsorships, and wealth management. The leasing segment provides a full spectrum of lease and equipment finance solutions and related services to a wide variety of businesses on a national basis. In April 2018, MB Financial reported that it planned to discontinue its national residential mortgage origination business. MB Financial plans to stop operating its mortgage business as a defined segment prior to the fourth quarter of 2018. MB Financial also plans to continue originating residential mortgage loans in the greater Chicago area and to retain its mortgage servicing asset as well as its mortgage servicing operation in Wilmington, Ohio. In addition, MB Financial plans to continue holding residential mortgage loans on its balance sheet.

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THE MERGER

The following is a discussion of the merger and the material terms of the merger agreement between Fifth Third and MB Financial. You are urged to read carefully the merger agreement in its entirety, a copy of which is attached as Appendix A to this proxy statement/prospectus and incorporated by reference herein. 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 the merger agreement carefully and in its entirety. This section is not intended to provide you with any factual information about Fifth Third or MB Financial. Such information can be found elsewhere in this proxy statement/prospectus and in the public filings Fifth Third and MB Financial make with the SEC. See “Where You Can Find More Information” in the forepart of this proxy statement/prospectus.

Terms of the Merger

Transaction Structure

Fifth Third’s, Intermediary’s and MB Financial’s Boards of Directors have approved the merger agreement and the merger. If the direct merger is approved by MB Financial’s common stockholders and preferred stockholders, then the merger agreement provides for the acquisition of MB Financial through the merger of MB Financial with and into Intermediary, with Intermediary continuing as the surviving corporation.

The merger agreement also provides that if the holders of MB Financial preferred stock do not approve the direct merger, but the holders of MB Financial common stock approve the alternative merger and charter amendment, then the acquisition of MB Financial will instead be effected by the merger of a newly-formed subsidiary of Fifth Third with and into MB Financial, with MB Financial surviving the alternative merger. Only if the direct merger is not approved by the MB Financial preferred stockholders will the alternative merger occur instead of the direct merger, if the applicable common stockholder approvals for the alternative merger and charter amendment are obtained.

Pursuant to the merger agreement, Fifth Third may at any time change the method of effecting the combination of Fifth Third and MB Financial. However, no such change may (i) alter or change the amount or kind of the merger consideration or the number of shares of Fifth Third common stock to be received by MB Financial’s common stockholders, (ii) adversely affect the tax treatment of Fifth Third shareholders or MB Financial stockholders, (iii) adversely affect the tax treatment of MB Financial or (iv) materially impede or delay the consummation of the merger.

Merger Consideration

Each share of MB Financial common stock issued and outstanding immediately prior to the effective time of the merger (other than shares owned by MB Financial or Fifth Third), will be converted into the right to receive 1.45 Fifth Third common shares and $5.54 in cash. In the direct merger, each share of MB Financial preferred stock issued and outstanding immediately prior to the effective time of the direct merger will automatically be converted into a share of new Fifth Third preferred stock. The new Fifth Third preferred stock will have substantially similar terms as the MB Financial preferred stock, except that the new Fifth Third preferred stock will have no voting rights (including upon an arrearage in the payment of dividends) except as required by Ohio law and will have certain other differences consistent with Fifth Third’s currently outstanding series of preferred stock and its articles of incorporation.

In the alternative merger, the holders of MB Financial common stock will receive the same merger consideration on the same terms as in the direct merger, but the MB Financial preferred stock will not be converted into a share of the new Fifth Third preferred stock and will instead remain outstanding and unchanged (except as noted in the next sentence) as preferred stock of MB Financial, which will be a subsidiary of Fifth Third. Pursuant to the

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charter amendment, effective immediately prior to consummation of the alternative merger, the holders of MB Financial preferred stock will have the right to vote with the holders of MB Financial common stock as a single class on all matters submitted to a vote of such common stockholders. Upon completion of the alternative merger, MB Financial will be a subsidiary of Fifth Third, who will control MB Financial as the sole holder of MB Financial common stock. MB Financial preferred stockholders will vote with Fifth Third as a single class on all matters submitted to a vote of Fifth Third, as the sole common stockholder of MB Financial following completion of the alternative merger. Thus, the voting rights that would be conferred upon the MB Financial preferred stockholders by the charter amendment would continue to apply with respect to MB Financial, and not Fifth Third, following completion of the alternative merger.

Conversion of Shares; Exchange and Payment Procedures

At or prior to the closing, Fifth Third will deposit or cause to be deposited with an exchange agent designated by Fifth Third and reasonably acceptable to MB Financial, for the benefit of the holders of shares of MB Financial common stock and MB Financial preferred stock, sufficient cash and Fifth Third common shares and, if issuable, new Fifth Third preferred stock to be exchanged in accordance with the merger agreement, including the merger consideration and payment of cash in lieu of fractional shares.

The conversion of MB Financial common stock into the right to receive the merger consideration and the conversion of the MB Financial preferred stock into the new Fifth Third preferred stock, if issuable, will occur automatically at the effective time of the merger. As promptly as practicable after the effective time of the merger, the exchange agent will exchange certificates representing shares of MB Financial common stock and, if applicable, MB Financial preferred stock for the merger consideration or new Fifth Third preferred stock to be received in the merger pursuant to the terms of the merger agreement.

Letters of Transmittal

As promptly as practicable after the effective time of the merger, but in any event within ten days thereafter, the exchange agent will send a letter of transmittal to only those persons who were MB Financial stockholders immediately prior to the effective time of the merger. This mailing will contain instructions on how to surrender shares of MB Financial common stock and, if applicable, MB Financial preferred stock in exchange for the merger consideration or new Fifth Third preferred stock the holder is entitled to receive under the merger agreement. From and after the effective time, MB Financial common stockholders who properly surrender their certificates or book entry shares to the exchange agent, together with a properly completed and duly executed letter of transmittal, and such other documents as may be required pursuant to such instructions, will receive for each share of MB Financial common stock 1.45 Fifth Third common shares, $5.54 in cash plus any cash payable in lieu of any fractional shares of Fifth Third common shares, and any dividends or distributions such holder has the right to receive pursuant to the merger agreement. No interest will be paid or accrue on any merger consideration or cash in lieu of fractional shares. From and after the effective time of the direct merger, MB Financial preferred stockholders who properly surrender their certificates or book entry shares to the exchange agent, together with a properly completed and duly executed letter of transmittal, and such other documents as may be required pursuant to such instructions, will receive for each share of MB Financial preferred stock a share of the new Fifth Third preferred stock and any dividends or distributions such holder has the right to receive pursuant to the merger agreement.

In the alternative merger, the MB Financial preferred stock will not be converted into a share of the new Fifth Third preferred stock and will instead remain outstanding as preferred stock of MB Financial, which will be a subsidiary of Fifth Third.

Dividends and Distributions

Until MB Financial common or preferred stock, if applicable, certificates or book entry shares are surrendered for exchange, any dividends or other distributions with a record date after the effective time of the merger with

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respect to Fifth Third common shares or new Fifth Third preferred stock into which shares of MB Financial common stock or preferred stock may have been converted will accrue but will not be paid. Fifth Third will pay to former MB Financial stockholders any unpaid dividends or other distributions, without interest, only after they have duly surrendered their MB Financial stock certificates or book entry shares. After the effective time of the merger, there will be no transfers on the stock transfer books of MB Financial of any shares of MB Financial common stock or MB Financial preferred stock. If certificates representing shares of MB Financial common stock or preferred stock, if applicable, or book entry shares are presented for transfer after the effective time of the merger, they will be cancelled and exchanged for the merger consideration or new Fifth Third preferred stock, if issuable, into which the shares of MB Financial common stock or MB Financial preferred stock represented by that certificate or book entry share have been converted.

Dissenting Shares

Under the Maryland General Corporation Law, the holders of MB Financial common stock and preferred stock will not have any appraisal rights with respect to the merger.

Lost, Stolen or Destroyed Stock Certificates

If a certificate for MB Financial common stock or preferred stock has been lost, stolen or destroyed, the exchange agent will issue the merger consideration or new Fifth Third preferred stock, if issuable, properly payable under the merger agreement upon receipt of appropriate evidence as to that loss, theft or destruction, appropriate evidence as to the ownership of that certificate by the claimant, and appropriate and customary indemnification.

Background of the Merger

As part of their efforts to enhance long-term value for their respective companies’ stockholders and other constituencies, the Boards of Directors of MB Financial and Fifth Third have periodically evaluated the strategic direction and business objectives of their respective companies. This process has entailed consideration of, among other things, strategic growth opportunities, the regulatory environment for financial institutions, economic and financial market conditions, competition, as well as consolidation and other developments in the financial services industry.

It was in this context that Mitchell Feiger, President and Chief Executive Officer of MB Financial, met with Gregory Carmichael, President and Chief Executive Officer of Fifth Third, and Timothy Spence, Executive Vice President of Payments, Strategy and Digital Solutions of Fifth Third, on May 6, 2016 at Mr. Spence’s suggestion. At this introductory meeting, the executives discussed the history, cultures and business models of their respective companies. While the possibility of a strategic business combination was not discussed, the executives agreed to meet again in the future to learn more about each other’s company. At the MB Financial Board of Directors meeting on May 25, 2016, Mr. Feiger briefed the board on his meeting with Messrs. Carmichael and Spence.

On September 12, 2017, Messrs. Feiger and Spence met again in Mr. Feiger’s office. Similar to the meeting in 2016, they discussed their respective companies and their strategies, with a specific emphasis on the Chicago banking environment and on some of MB Financial’s specialty business lines, but a specific business combination transaction was not discussed. They agreed to continue the dialogue to learn more about each other’s company. At the MB Financial Board of Directors meeting on September 27, 2017, Mr. Feiger briefed the MB Financial Board of Directors on his meeting with Mr. Spence.

On October 25 through October 27, 2017, the MB Financial Board of Directors had its annual board strategic planning retreat. On October 25, 2017, a representative from Sandler O’Neill attended a portion of the retreat to discuss with the board a wide range of topics including the current U.S. economic outlook, the bank operating

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environment and M&A outlook, potential acquirors of MB Financial, potential merger of equals candidates and potential acquisition targets for MB Financial. The board’s takeaway from the discussion was that the best opportunities for MB Financial in the near term would be to continue its organic growth and profit improvement strategies as well as opportunistically acquire smaller banking institutions with high quality deposit bases in the Chicago market or in the payments, cards or specialty finance businesses.

On November 22, 2017, Messrs. Carmichael, Spence and Feiger, together with Tayfun Tuzun, Executive Vice President and Chief Financial Officer of Fifth Third, met for dinner. Similar to prior meetings, the executives discussed their respective companies. In addition, the Fifth Third executives discussed the potential strategic benefits of a combination between MB Financial and Fifth Third. Mr. Carmichael expressed to Mr. Feiger Fifth Third’s desire to proceed with discussions for a potential strategic combination and suggested that Mr. Feiger travel to Fifth Third’s corporate headquarters in Cincinnati, Ohio to meet the Fifth Third executive management team and learn more about Fifth Third. At the MB Financial Board of Directors meeting on December 13, 2017, Mr. Feiger briefed the board on the dinner meeting, including Fifth Third’s expression of interest in discussing a potential business combination transaction, and received approval for him and Mark Hoppe, President and Chief Executive Officer of MB Financial Bank, to visit Fifth Third.

On December 19, 2017, the Fifth Third board held a regularly scheduled meeting and the discussion included potential acquisition partners, including MB Financial, and the strategic benefits and financial considerations of potential acquisitions.

On February 20, 2018, Messrs. Feiger and Hoppe visited Fifth Third headquarters and met with several members of the Fifth Third senior management team. The executives reviewed in detail many of the strategic benefits of a combination including the unique opportunity to create a leading Chicago bank, the benefits of combining their respective businesses and the complementary nature of many of their respective business segments. In addition, the executives noted that the two organizations have a similar customer focus and complementary cultures. Furthermore, considering the overlap of the branch networks and certain back office functions, the executives believed that the potential expense synergies in a merger would be significant. While Fifth Third did not discuss a specific purchase price, its executives did provide their thoughts on an initial framework for a potential combination. Mr. Feiger and Mr. Hoppe reported on this meeting to MB Financial’s Board of Directors on February 28, 2018 and provided board members with the Fifth Third discussion materials that were reviewed. After a discussion regarding the potential strategic benefits of a potential combination with Fifth Third, the board authorized Mr. Feiger to continue discussions with Fifth Third.

On February 27, 2018, the Fifth Third board met and the board continued its prior discussion of potential acquisition partners, including MB Financial, with a review of the strategic benefits of potential acquisitions and the opportunity to create shareholder value for Fifth Third’s shareholders.

On March 1, 2018, MB Financial and Fifth Third entered into a mutual non-disclosure agreement and Mr. Feiger and Mr. Spence spoke telephonically to update each other on their recent board meetings. Both executives noted that their respective boards recognized the strategic benefits of a potential combination and approved continuing discussions and bringing in selected executives from each side. At such time, Mr. Feiger advised Mr. Spence that if Fifth Third decided to propose a transaction that would attract interest from the MB Financial Board of Directors, then MB Financial would also assess the interest of other parties in a possible acquisition.

On March 5, 2018, Mr. Feiger and Jill York, Executive Vice President of Specialty Banking and M&A of MB Financial, spoke by telephone with Mr. Spence, James Leonard, Treasurer of Fifth Third, and Saema Somalya, Deputy General Counsel of Fifth Third. The discussion primarily covered a proposed timeline to permit Fifth Third to form an initial view on transaction economics and the items that each side would provide for preliminary due diligence and preliminary reverse due diligence. In addition, the executives scheduled a dinner meeting in Rosemont, Illinois and strategy session for management to share more detailed information about their respective businesses.

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On March 10, 2018, MB Financial and Fifth Third provided each other with access to a secure data site for the commencement of due diligence by Fifth Third and reverse due diligence by MB Financial.

On March 14, 2018, Mr. Feiger had a previously scheduled meeting with the senior management team of another potential interested party, which we refer to as “Party A.” At the meeting, the Chief Executive Officer of Party A indicated that Party A would be interested in acquiring MB Financial if it ever were to consider a sale.

On March 14, 2018, members of the senior management of MB Financial, Fifth Third and their respective banking subsidiaries had a dinner meeting in Rosemont, Illinois. The following day the discussions continued in person and covered a wide range of topics including a review of each company’s retail, wealth management, mortgage, commercial banking and leasing business lines, as well as critical risk functions, risk appetite, financial performance, culture and core values. The MB Financial senior management team came away from the discussion with a view that the culture and core values of the companies were compatible and there was strategic merit to continuing discussions.

On March 16, 2018, Mr. Spence had a follow up discussion with Ms. York to provide additional information on Fifth Third’s payments business. Mr. Spence and Ms. York also exchanged feedback from the March 14 and 15, 2018 meetings. Key takeaways were that the two companies managed risk in a similar way, that in addition to significant cost synergies, there were significant revenue enhancement opportunities and that the dialogue in the meetings was collaborative.

On March 23, 2018, Mr. Feiger and Ms. York had a follow up telephone call with Messrs. Carmichael, Spence, Tuzun and Leonard to discuss Fifth Third’s feedback from the management meetings and their initial view on transaction economics based on the preliminary due diligence information. Mr. Carmichael shared that they were very positive on the opportunity and that a combined company would have a much more attractive presence in Chicago. While there was significant information left to review, Fifth Third provided its initial views on a pricing framework for a transaction, which included an illustrative 15% premium to MB Financial’s common stock trading price. Mr. Feiger and Ms. York asked questions regarding some of the assumptions included in the Fifth Third analysis and provided some suggestions for additional financial analysis which might help Fifth Third increase its pricing. Over the following week, Ms. York and Mr. Leonard continued to share information in order to refine the assumptions used by both sides in their financial analysis of a potential transaction.

On March 28, 2018, Mr. Feiger, Ms. York, Mr. Tuzun and Mr. Leonard had a telephone call to discuss their respective financial models with the objective of gaining an understanding of each side’s assumptions. Specific assumptions such as cost savings, transaction-related costs, estimated core deposit intangible and other purchase accounting estimates were reviewed. In addition, Mr. Spence, Mr. Carmichael and Mr. Feiger continued to discuss the purchase price premium framework and assumptions.

On March 29, 2018, Mr. Feiger had a telephone call with Mr. Carmichael, who reiterated Fifth Third’s desire to consummate a transaction with MB Financial given the strategic benefits and indicated that Fifth Third could pay a 25% market premium and would add one MB Financial director to its board of directors. Later that evening, the MB Financial Board of Directors held a conference call meeting to discuss the status of the discussions with Fifth Third. Mr. Feiger and Ms. York provided an update regarding the recent discussions, a summary of potential transaction economics and a comparison to MB Financial’s standalone internal projections under various interest rate scenarios. The potential transaction analyses were prepared using a premium of 25% to MB Financial’s current common stock price. The MB Financial Board of Directors engaged in a robust discussion and concluded that senior management should continue discussions with Fifth Third and requested that MB Financial’s financial advisor, Sandler O’Neill, assist with MB Financial’s evaluation of a potential transaction with Fifth Third and MB Financial’s other strategic alternatives.

On March 30, 2018, Mr. Feiger, Ms. York and Randall Conte, Chief Operating Officer and Chief Financial Officer of MB Financial, shared with representatives of Sandler O’Neill relevant financial information gathered up to that point in time, including key transaction assumptions.

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On April 12, 2018, Mr. Feiger met with members of senior management of Party A. After discussing the banking business generally, and segments of MB Financial’s banking business specifically, Party A representatives indicated an interest in commencing a dialogue regarding a possible acquisition of MB Financial. Mr. Feiger indicated that he would discuss Party A’s possible interest in a transaction with the MB Financial Board of Directors and provide the board’s response to Party A.

On April 14, 2018, Ms. York had a telephone conversation with Mr. Leonard and representatives from Fifth Third’s financial advisor. The purpose of the call was to discuss certain financial assumptions relating to MB Financial’s future performance.

On April 19, 2018, Mr. Feiger spoke by telephone with the head of corporate strategy of Party A, who indicated that while Party A would like to move forward with acquisition discussions, Party A would prefer to wait until the summer which would be better timing for Party A.

On April 20, 2018, Messrs. Feiger and Spence had a phone call to discuss transaction terms. Mr. Spence indicated that Fifth Third would be willing to offer a 25% market premium, which equated to an implied price of $53.03 per MB Financial common share based on the prior day’s closing price of Fifth Third common stock. The consideration would be all stock or, at MB Financial’s election, up to 10% in cash. Fifth Third also re-affirmed its offer to add one MB Financial director to its board of directors.

On April 21, 2018, the MB Financial Board of Directors convened a telephonic meeting. All board members were in attendance as well as representatives of Sandler O’Neill and a representative of the law firm of Silver, Freedman, Taff & Tiernan LLP, which we refer to as “Silver Freedman.” At the meeting, representatives of Sandler O’Neill reviewed with the MB Financial Board of Directors the financial aspects of Fifth Third’s 25% premium to market pricing proposal, in an all-stock transaction, based on various financial metrics, as well as the potential capacity to pay of Fifth Third and certain other institutions, including Party A, based on publicly available information. Sandler O’Neill observed that the proposed pricing in Fifth Third’s offer was at the higher end of pricing ranges for recent transactions. Sandler O’Neill also concluded that the proposed pricing reflected serious interest on the part of Fifth Third to complete a transaction with MB Financial. After discussion, including an update on the possible interest of Party A, the MB Financial Board of Directors instructed senior management to continue discussions with Fifth Third and to contact Party A to determine whether Party A would be interested in pursuing a potential transaction at this time. The MB Financial Board of Directors also instructed Sandler O’Neill to contact two other parties, including Party B (selected in consultation with Sandler O’Neill based on their size and expected ability to pay a transaction premium as well as their potential level of interest in pursuing a transaction with MB Financial), on a no names basis, to assess their interest in a possible transaction in the Midwest. After the board meeting, Mr. Feiger contacted the head of corporate strategy of Party A to determine whether Party A would be interested in pursuing a transaction with MB Financial, on an immediate and accelerated timetable. Party A’s representative confirmed Party A’s interest in a possible transaction, the parties entered into a mutual non-disclosure agreement and Party A was granted access to a secure data site to commence its due diligence.

From April 22, 2018 through May 17, 2018, Fifth Third continued its due diligence and Party A performed its due diligence on MB Financial, which included access to information on secure data sites, in person meetings and telephonic communications with MB Financial management. During this period MB Financial performed reverse due diligence on both Fifth Third and Party A.

On April 23, 2018, Sandler O’Neill contacted two other parties, including Party B, on a no names basis, to assess their interest in a possible commercial bank transaction in the Midwest. The contacted parties, including Party B initially, indicated that they would not be interested at the present time in pursuing a transaction due to timing issues among other factors.

On April 24, 2018, the members of the MB Financial Board of Directors received additional and updated information from Sandler O’ Neill for discussion relating to Fifth Third’s oral offer, which included, among other

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information, MB Financial’s standalone common stock implied value under various scenarios; a comparison of Fifth Third’s oral offer to recent transaction precedents and MB Financial’s standalone common stock implied value, potential market reaction based upon the earn back period of tangible book value dilution, and other potential benefits and risks associated with a transaction with Fifth Third; and the potential capacity to pay of Party A and Party B as well as the other parties considered by Sandler O’Neill in its assessment of possible interest by other suitors.

On April 25, 2017, the MB Financial Board of Directors held its regularly scheduled board meeting, which was also attended in person by representatives of Sandler O’Neill and a representative of Silver Freedman. The representatives of Sandler O’Neill discussed financial matters relating to MB Financial under various standalone scenarios and a possible transaction with Fifth Third. The directors and representatives of Sandler O’Neill also discussed a possible transaction with Party A, including, among other things, Party A’s apparent capacity to pay. Sandler O’Neill informed the board that Party A was expected to provide an oral indication of pricing and consideration mix by April 29, 2018. The representative of Silver Freedman reviewed with the directors the applicable legal standards in connection with the board’s review of potential strategic alternatives, including a potential merger. After further discussion, it was the consensus of the board that the oral offer provided by Fifth Third was sufficient to merit continuing the strategic discussions with Fifth Third, Party A and other possible suitors. At the conclusion of the meeting, the board instructed Silver Freedman to draft a form of definitive agreement for submission to interested parties.

During the evening of April 25, 2018, Mr. Feiger had dinner with Messrs. Carmichael, Tuzun and Spence and two independent directors of MB Financial. At the dinner meeting, the Fifth Third representatives shared their ideas for the combined company and reasons why Fifth Third would be a good partner for MB Financial. Before the meeting concluded, Mr. Feiger advised the Fifth Third representatives that he expected other interested parties to join the sale process.

On April 27, 2018, Party B contacted Sandler O’Neill to express its interest in a possible acquisition of a Midwestern commercial bank if the potential target was MB Financial. A draft mutual non-disclosure agreement was provided by MB Financial to Party B on the same day.

On April 28, 2018, Party A submitted its initial oral indication of pricing and consideration mix to MB Financial. The proposal provided for pricing of $54.00 per MB Financial common share with a cash component of $0.5 billion to $2.0 billion and the remaining consideration in Party A’s common stock. The exchange ratio for the stock portion of the consideration would be calculated prior to deal signing.

On April 29, 2018, the MB Financial Board of Directors held a telephonic meeting to discuss and evaluate Party A’s proposal. Sandler O’Neill presented updated materials to include an analysis of Party A’s indication of pricing and consideration mix. After a review of the Sandler O’Neill materials and a discussion of other potential benefits and risks of a transaction with Party A, the board authorized management to continue the pursuit of a possible transaction with both Fifth Third and Party A.

On April 30, 2018, Sandler O’Neill had discussions with the financial advisors to Fifth Third and Party A relating to the first draft of a definitive agreement. Each of Fifth Third and Party A indicated a preference for its outside counsel to prepare the initial draft, which in the case of Fifth Third had already been started by its counsel.

On May 1, 2018, Party B and MB Financial signed a mutual non-disclosure agreement and Party B was granted access to a secure data site to commence its due diligence on MB Financial.

From May 1, 2018 through May 13, 2018, Party B conducted due diligence on a secure data site and through communications with Sandler O’Neill and MB Financial management.

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On May 4, 2018, representatives of Silver Freedman had telephone conferences with outside counsel to each of Fifth Third and Party A relating to expectations with respect to the substance of the definitive agreement being drafted by each counsel and the timing for receipt of the initial draft.

On May 9, 2018, outside counsel to Party A provided an initial draft of a definitive agreement to Silver Freedman. From that point through May 16, 2018, Silver Freedman and outside counsel to Party A exchanged additional drafts of the definitive agreement and participated in discussions and negotiations relating thereto.

On the evening of May 10, 2018, the Fifth Third board met and discussed with management and Fifth Third’s advisors the potential transaction with MB Financial, including the potential strategic benefits and financial considerations. After full discussion, the board authorized management to proceed with further negotiations.

Thereafter on May 10, 2018, Simpson Thacher & Bartlett LLP, which we refer to as “Simpson Thacher,” counsel to Fifth Third, provided an initial draft of a definitive agreement to Silver Freedman. From that point through May 20, 2018, Silver Freedman and Simpson Thacher exchanged multiple revised drafts of the definitive agreement and participated in discussions and negotiations with respect to each draft.

On May 12, 2018, Sandler O’Neill spoke by phone with a representative of Party A and relayed to Party A MB Financial’s offer of the opportunity to speak with or present to the MB Financial Board of Directors. The representative of Party A notified Sandler O’Neill that they would consider MB Financial’s offer and would notify Sandler O’Neill if Party A decided to accept that invitation.

On May 14, 2018, Party B advised Sandler O’Neill that it would not be providing an indication of interest to acquire MB Financial due in large part to the expectation, based in part on its discussions with Sandler O’Neill, that transaction pricing would need to be well above precedent medians.

On the evening of May 14, 2018 and the morning of May 15, 2018, the Fifth Third board met and discussed with management and its advisors the status of the negotiations as well as the results of the ongoing due diligence review of MB Financial. At the conclusion of these meetings, the Fifth Third board authorized management to submit an updated proposal to MB Financial and enter into further negotiations with respect to a business combination transaction.

On May 15, 2018, Messrs. Carmichael, Tuzun and Spence made an in person presentation to members of the MB Financial Board of Directors relating to the strategic benefits of a combination between the parties and answered questions of the directors relating to Fifth Third and its business. At that meeting, Fifth Third provided pricing of a fixed exchange ratio of 1.427 shares of Fifth Third common stock plus $5.40 in cash for each MB Financial common share, representing an implied value of $53.95 per share based on Fifth Third’s closing price on May 14, 2018.

On May 15, 2018, in response to a request from Sandler O’Neill, on behalf of MB Financial, for updated pricing, Party A provided updated pricing and consideration mix of $54.00 per MB Financial common share with the cash component of the aggregate consideration being equal to $1.2 billion and the remainder of the aggregate consideration to be in Party A common stock based on an exchange ratio to be calculated and fixed prior to deal signing.

On May 16, 2018, the MB Financial Board of Directors held a meeting, which was also attended in person by representatives of Sandler O’Neill and representatives of Silver Freedman. Sandler O’Neill provided updated information and analysis relating to the competing offers of Fifth Third and Party A. After review and discussion of the updated information and analysis, it was the consensus of the board that the proposals of both Fifth Third and Party A presented MB Financial common stockholders with significant value when compared to MB Financial’s standalone valuation with its current strategy. The directors then discussed their views with respect to each proposal. A representative of Silver Freedman then reviewed with the directors their fiduciary duties under

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Maryland law with respect to their evaluation of the competing proposals. After a full discussion relating to both proposals, which included extensive dialogue by the board members with representatives of Sandler O’Neill, it was the consensus of the board that the Fifth Third proposal was the superior proposal based on the strength and potential upside of its common stock (and the greater percentage of its offer comprised of common stock, compared to Party A), as well as Fifth Third’s complementary business model and operating fit with MB Financial and greater opportunity for significant cost savings and synergies. The board then instructed Sandler O’Neill to solicit best and final offers from both parties, and to also request two seats on Fifth Third’s Board of Directors, reflecting the pro forma equity ownership of the MB Financial’s stockholders in the combined company. The meeting then adjourned with the understanding that it would be reconvened the same evening. At the reconvened meeting, representatives of Sandler O’Neill informed the board that Fifth Third was willing to improve its pricing to a fixed exchange ratio of 1.450 shares of Fifth Third common stock plus $5.54 in cash for each MB Financial common share, representing an implied value of $55.35 per share based on Fifth Third’s closing price on May 16, 2018 and Fifth Third was willing to add two members of the MB Financial board to its board. Further, representatives of Sandler O’Neill informed the board that Party A had increased its offer to $56.00 per MB Financial common share. The increased offer by Party A represented an implied value of $0.65 per share greater than the implied value per share of the Fifth Third offer at such time. After extensive discussion, the board authorized management and its advisors to proceed with Fifth Third given the higher expected long-term value to MB Financial’s stockholders from the Fifth Third proposal, based on the factors discussed above, when compared to the proposal from Party A. The MB Financial Board of Directors authorized management and its advisors to finalize an acceptable definitive agreement with Fifth Third, subject to MB Financial completing its reverse due diligence on Fifth Third.

On May 18, 2018, through an email to Sandler O’Neill, Party A formally withdrew its interest to acquire MB Financial. Later that day, MB Financial entered into an exclusivity agreement with Fifth Third through May 22, 2018.

Early on May 20, 2018, the MB Financial Board of Directors held a telephonic meeting to consider and vote on the final terms of the proposed transaction with Fifth Third. A representative of Silver Freedman reviewed the execution version of the definitive merger agreement with the board including the minor changes that had been made from the draft previously provided to the directors. Representatives of Sandler O’Neill then orally delivered an opinion to the MB Financial Board of Directors to the effect that as of May 20, 2018, the merger consideration was fair to holders of MB Financial common stock from a financial point of view. The board then unanimously approved the merger agreement, the merger and the other transactions contemplated by the merger agreement, and authorized management to execute and deliver the merger agreement.

Also on May 20, 2018, the Fifth Third board met with management and its advisors to consider and vote on the final terms of the proposed transaction with MB Financial. After discussion, the board voted to approve the merger agreement, the merger and the other transactions contemplated by the merger agreement, and authorized management to execute and deliver the merger agreement. That evening the merger agreement was executed by the parties.

On May 21, 2018, the transaction was announced in a joint press release before the opening of stock markets in New York.

Recommendation of the MB Financial Board of Directors and Reasons for the Merger

In reaching its decision to approve the merger agreement, the merger and the other transactions contemplated by the merger agreement, and to recommend that MB Financial preferred stockholders approve the preferred stockholder merger proposal and that MB Financial common stockholders approve the common stockholder merger proposal and the charter amendment proposal, the MB Financial Board of Directors evaluated the merger agreement, the merger and the other transactions contemplated by the merger agreement in consultation with MB

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Financial management, as well as MB Financial’s financial and legal advisors, and considered a number of factors, including the following:

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The foregoing discussion of the information and factors considered by the MB Financial Board of Directors is not intended to be exhaustive, but includes the material factors considered by the MB Financial Board of Directors. In reaching its decision to approve the merger agreement, the merger and the other transactions contemplated by the merger agreement, the MB Financial Board of Directors did not quantify or assign any relative weights to the factors considered, and individual directors may have given different weights to different factors. The MB Financial Board of Directors considered all these factors as a whole, including discussions with MB Financial’s management and MB Financial’s financial and legal advisors, and overall considered the factors to be favorable to, and to support, its determination.

The foregoing discussion of the information and factors considered by the MB Financial Board of Directors is forward-looking in nature. This information should be read in light of the factors described under the section entitled “Cautionary Statement Regarding Forward-Looking Statements.”

For the reasons set forth above, the MB Financial Board of Directors determined that the merger agreement and the transactions contemplated by the merger agreement are advisable and in the best interests of MB Financial and its stockholders, and approved the merger agreement and the transactions contemplated thereby. The MB Financial Board of Directors recommends that holders of MB Financial common stock vote “FOR” the common stockholder merger proposal, “FOR” the charter amendment proposal, “FOR” the merger-related compensation proposal and “FOR” the common stockholder adjournment proposal (if necessary or appropriate), and recommends that holders of MB Financial preferred stock vote “FOR” the preferred stockholder merger proposal and “FOR” the preferred stockholder adjournment proposal (if necessary or appropriate).

Certain MB Financial Prospective Financial Information

MB Financial has made limited public disclosure of forecasts or projections of its expected financial performance because of, among other things, the inherent difficulty of accurately predicting financial performance for future periods and the inherent uncertainty of the underlying assumptions. However, MB Financial management provided Sandler O’Neill with certain nonpublic unaudited prospective financial information prepared by MB Financial management that was utilized by Sandler O’Neill for purposes of financial analyses performed in connection with its fairness opinion, as described under “—Opinion of MB Financial’s Financial Advisor” beginning on page 59. A summary of certain significant elements of this information is set forth below and is included in this proxy statement/prospectus solely because such information was made available to Sandler O’Neill in connection with its fairness opinion. The information included below does not comprise all of the prospective financial information provided by MB Financial to Sandler O’Neill.

The prospective financial information for MB Financial reflects numerous estimates and assumptions with respect to industry performance, general business, economic, regulatory, market and financial conditions and other future events, as well as matters specific to MB Financial’s business, all of which are inherently uncertain and difficult to predict and many of which are beyond MB Financial’s control. The prospective financial information is subjective in many respects and thus is susceptible to multiple interpretations and periodic revisions based on actual experience and business developments. The prospective financial information may also be affected by MB Financial’s ability to achieve strategic goals, objectives and targets over the applicable periods. As such, the prospective financial information constitutes forward-looking information and is subject to risks and uncertainties, including the risks and uncertainties described under “Risk Factors,” beginning on page 27, “Cautionary Statement Regarding Forward-Looking Statements,” beginning on page 25, and in MB

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Financial’s Annual Report on Form 10-K for the year ended December 31, 2017 and the other reports filed by MB Financial with the SEC that are incorporated by reference into this proxy statement/prospectus, as described under “Incorporation of Certain Documents by Reference,” beginning on page 133.

The prospective financial information for MB Financial was generally not prepared with a view toward public disclosure or complying with GAAP, the published guidelines of the SEC regarding forward-looking statements or the guidelines established by the American Institute of Certified Public Accountants for preparation and presentation of prospective financial information. Neither MB Financial’s independent registered public accounting firm, nor any other independent accountants, have compiled, examined or performed any procedures with respect to the prospective financial information included below, nor have they expressed any opinion or any other form of assurance on such information or its achievability, and they assume no responsibility for, and disclaim any association with, the prospective financial information. Furthermore, the prospective financial information does not take into account any circumstances or events occurring after the date it was prepared.

You are strongly cautioned not to place undue reliance on the prospective financial information set forth below. The inclusion of the prospective financial information in this proxy statement/prospectus should not be regarded as an indication that any of MB Financial, Fifth Third or their respective affiliates, advisors or representatives considered or consider the prospective financial information to be necessarily predictive of actual future events, and the prospective financial information should not be relied upon as such. None of MB Financial, Fifth Third or their respective affiliates, advisors or representatives can give any assurance that actual results will not differ from the prospective financial information, and none of them undertakes any obligation to update or otherwise revise or reconcile the prospective financial information to reflect circumstances existing after the date such information was prepared or to reflect the occurrence of future events even in the event that any or all of the assumptions underlying the prospective financial information are shown to be in error or to reflect changes in general economic or industry conditions. None of MB Financial, Fifth Third or their respective affiliates, advisors or representatives makes any representation to any stockholder regarding the projections.

In light of the foregoing, and considering that the special meeting will be held several months after the prospective financial information was prepared, as well as the uncertainties inherent in any forecasted information, MB Financial’s stockholders are cautioned not to place unwarranted reliance on such information, and Fifth Third and MB Financial urge all stockholders to review MB Financial’s most recent SEC filings for a description of MB Financial’s reported financial results. See “Where You Can Find More Information” in the forepart of this proxy statement/prospectus and “Incorporation of Certain Documents by Reference,” beginning on page 133.

The prospective financial information summarized in this section is not being included in this proxy statement/prospectus in order to induce any MB Financial stockholder to vote in favor of any of the proposals to be voted on at the special meeting.

The following table presents summary selected unaudited prospective financial information of MB Financial prepared by MB Financial’s management. This information excludes the results of MB Financial’s national residential mortgage origination business, which MB Financial is in the process of exiting, along with the related exit costs.