On April 1, 2008, O’Reilly Automotive, Inc., a Missouri corporation (“O’Reilly”), OC Acquisition Company, a Delaware corporation and an indirect wholly-owned subsidiary of O’Reilly (“Merger Sub”) and CSK Auto Corporation, a Delaware corporation (“CSK”), entered into an Agreement and Plan of Merger (the “Merger Agreement”).

The Merger Agreement provides that, on and subject to the terms of the Merger Agreement, Merger Sub will commence an exchange offer (the “Offer”), within ten business days of receiving the required information from CSK, to purchase all of the outstanding shares (the “Shares”) of CSK common stock, $0.01 par value, for (a) a fraction of a share of O’Reilly common stock based on exchange ratio (subject to the collar as described below) equal to $11.00 divided by the average trading price of O’Reilly common stock for the five consecutive trading days ending on and including the second trading day prior to the consummation of the Offer plus (b) $1.00 in cash (subject to reduction for costs associated with obtaining credit agreement waivers or amendments, if any, incurred by CSK over $3 million); provided, however, that if the average trading price of O’Reilly common stock is greater than $29.95, then the exchange ratio shall equal 0.3673, and if the average trading price is less than $25.67, then the exchange ratio shall equal 0.4285 (the sum of (a) and (b) being the “Offer Price”).

Following consummation of the Offer, Merger Sub will merge with and into CSK with CSK surviving as a wholly-owned subsidiary of O’Reilly (the “Merger”). In the Merger, each outstanding Share that is not tendered and accepted pursuant to the Offer (other than the Shares held in the treasury of CSK, owned by O’Reilly, Merger Sub, or any subsidiary of O’Reilly or CSK immediately prior to the effective time of the Merger, and other than the Shares as to which appraisal rights have been perfected in accordance with applicable law) will be cancelled and converted into the right to receive the Offer Price, on the terms and conditions set forth in the Merger Agreement. At the effective time of the Merger, (i) each outstanding option to acquire CSK common stock will be converted into the right to receive a number of shares of O’Reilly common stock equal to the number of shares subject to such stock option multiplied by an exchange ratio based upon the Offer Price and (ii) each other unvested equity-based award will be converted into an equity-based award relating to a number of shares of O’Reilly common stock equal to the number of shares subject to such equity-based award multiplied by an exchange ratio based upon the Offer Price.

Consummation of the Offer is subject to various conditions, including, but not limited to (i) at least a majority of shares of CSK common stock then outstanding on a fully diluted basis being tendered into the Offer, (ii) the expiration or termination of the applicable Hart-Scott-Rodino waiting period, (iii) the registration statement for O’Reilly’s common stock issuable in connection with the Offer and Merger being declared effective and the listing of such shares on Nasdaq, (iv) receipt of opinions of counsel regarding tax-free reorganization and (v) the absence of any Material Adverse Effect (as defined in the Merger Agreement) with respect to CSK’s business. The Offer is not subject to a financing condition.

The Offer will expire at midnight, New York time, on the 20th business day following and including the commencement date, unless extended in accordance with the terms of the Offer and the Merger Agreement and the applicable rules and regulations of the Securities and Exchange Commission (the “SEC”).

The consummation of the Merger is subject to various additional conditions, including, if required under Delaware law, approval of the Merger Agreement by CSK stockholders. The parties have agreed that if after the purchase of Shares pursuant to the Offer and any subsequent offering period, and after giving effect to any shares of CSK common stock purchased pursuant to the option described in the next paragraph, Merger Sub owns at least 90% of the outstanding Shares, then once the other conditions of the Merger are satisfied or waived, Merger Sub will merge into CSK in a “short-form” merger pursuant to the applicable provisions of Delaware law which will not require a vote of CSK’s stockholders.

In the Merger Agreement, CSK has granted to O’Reilly and Merger Sub an option (the “Top Up Option”) to purchase, at a price per share equal to the Offer Price, a number of newly issued shares of CSK common stock equal to the lowest number of shares that, when added to the number of Shares owned, directly or indirectly, by O’Reilly or Merger Sub at the time of exercise of the Top Up Option, constitutes one share more than 90% of the fully diluted shares of CSK common stock (after giving effect to the issuance of all shares subject to the Top Up Option). O’Reilly or Merger Sub may exercise the Top Up Option, in whole or in part, provided that upon exercise of the Top Up Option, O’Reilly will directly or indirectly own one share more than 90% of the outstanding Shares (after giving effect to the issuance of shares of CSK common stock pursuant to the exercise of the Top Up Option), at any time on or after the consummation of the Offer and prior to (i) the effective time of the Merger and (ii) the termination of the Merger Agreement in accordance with its terms.

In addition, pursuant to the terms of the Merger Agreement, effective upon the purchase of Shares pursuant to the Offer, O’Reilly will be entitled to designate a number of directors, rounded up to the next whole number, on CSK’s Board of Directors and Board committees equal to the product of (i) the total number of directors on CSK’s Board of Directors or Board committee, as applicable, and (ii) the percentage that the number of Shares beneficially owned by O’Reilly and/or Merger Sub bears to the number of Shares then outstanding.