VOTING AGREEMENT

Exhibit 2.3

VOTING AGREEMENT

THIS VOTING AGREEMENT (this “Agreement”) is dated as of January 30, 2014, by and between the undersigned holder (“Shareholder”) of Common Stock, $0.01 par value per share, of Summit Bancorp, Inc., an Arkansas corporation with its principal office in Arkadelphia, Arkansas (“Company”), and Bank of the Ozarks, Inc., an Arkansas corporation (“Buyer”) with its principal office in Little Rock, Arkansas. All capitalized terms used but not defined herein shall have the meanings assigned to them in the Merger Agreement (defined below).

WHEREAS, concurrently with the execution of this Agreement, Buyer, Buyer’s wholly owned subsidiary, Bank of the Ozarks, an Arkansas state banking corporation (“Buyer Bank”), Company and Company’s wholly owned subsidiary, Summit Bank, an Arkansas state banking corporation (“Company Bank”), are entering into an Agreement and Plan of Merger (as such agreement may be subsequently amended or modified, the “Merger Agreement”), pursuant to which (i) Company will merge with and into Buyer, with Buyer as the surviving entity and (ii) Company Bank will merge with and into Buyer Bank, with Buyer Bank as the surviving entity (collectively, the “Merger”), and in connection with the Merger, each outstanding share of Company Common Stock will be converted into the right to receive the Merger Consideration;

WHEREAS, Shareholder beneficially owns and has sole voting power with respect to the number of shares of Company Common Stock as indicated on the signature page of this Agreement under the heading “Total Number of Shares of Company Common Stock Subject to this Agreement” (such shares, together with any additional shares of Company Common Stock subsequently acquired by Shareholder during the term of this Agreement, including through the exercise of any stock option or other equity award, warrant or similar instrument, being referred to collectively as the “Shares”); and

WHEREAS, it is a material inducement to the willingness of Buyer to enter into the Merger Agreement that Shareholder execute and deliver this Agreement.

NOW, THEREFORE, in consideration of, and as a material inducement to, Buyer entering into the Merger Agreement and proceeding with the transactions contemplated thereby, and in consideration of the expenses incurred and to be incurred by Buyer in connection therewith, Shareholder and Buyer agree as follows:

Section 1. Agreement to Vote Shares. Shareholder agrees that, while this Agreement is in effect, at any meeting of shareholders of Company, however called, or at any adjournment thereof, or in any other circumstances in which Shareholder is entitled to vote, consent or give any other approval, except as otherwise agreed to in writing in advance by Buyer, Shareholder shall:

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Shareholder further agrees not to vote or execute any written consent to rescind or amend in any manner any prior vote or written consent, as a shareholder of Company, to approve or adopt the Merger Agreement unless this Agreement shall have been terminated in accordance with its terms.

Section 2. No Transfers. While this Agreement is in effect, Shareholder agrees not to, directly or indirectly, sell, transfer, pledge, assign or otherwise dispose of, or enter into any contract option, commitment or other arrangement or understanding with respect to the sale, transfer, pledge, assignment or other disposition of, any of the Shares, except the following transfers shall be permitted: (a) transfers by will or operation of law, in which case this Agreement shall bind the transferee, (b) transfers pursuant to any pledge agreement, subject to the pledgee agreeing in writing, prior to such transfer, to be bound by the terms of this Agreement, (c) transfers in connection with estate and tax planning purposes, including transfers to relatives, trusts and charitable organizations, subject to each transferee agreeing in writing, prior to such transfer, to be bound by the terms of this Agreement, and (d) such transfers as Buyer may otherwise permit in its sole discretion. Any transfer or other disposition in violation of the terms of this Section 2 shall be null and void.

Section 3. Representations and Warranties of Shareholder. Shareholder represents and warrants to and agrees with Buyer as follows:

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Section 4. No Solicitation. From and after the date hereof until the termination of this Agreement pursuant to Section 6 hereof, Shareholder, in his, her or its capacity as a shareholder of Company, shall not, nor shall such Shareholder authorize any partner, officer, director, advisor or representative of, such Shareholder or any of his, her or its affiliates to (and, to the extent applicable to Shareholder, such Shareholder shall use commercially reasonable efforts to prohibit any of his, her or its representatives or affiliates to), (a) initiate, solicit, induce or knowingly encourage, or knowingly take any action to facilitate the making of, any inquiry, offer or proposal which constitutes, or could reasonably be expected to lead to, an Acquisition Proposal, (b) participate in any discussions or negotiations regarding any Acquisition Proposal, or furnish, or otherwise afford access, to any person (other than Buyer) any information or data with respect to Company or otherwise relating to an Acquisition Proposal, (c) enter into any agreement, agreement in principle, letter of intent, memorandum of understanding or similar arrangement with respect to an Acquisition Proposal, (d) solicit proxies with respect to an Acquisition Proposal (other than the Merger Agreement) or otherwise encourage or assist any party in taking or planning any action that would compete with, restrain or otherwise serve to interfere with or inhibit the timely consummation of the Merger in accordance with the terms of the Merger Agreement, or (e) initiate a shareholders’ vote or action by consent of Company’s shareholders with respect to an Acquisition Proposal.

Section 5. Irrevocable Proxy. Subject to the last sentence of this Section 5, by execution of this Agreement, Shareholder does hereby appoint Buyer with full power of substitution and resubstitution, as Shareholder’s true and lawful attorney and irrevocable proxy, to the full extent of Shareholder’s rights with respect to the Shares, to vote, if Shareholder is unable to perform his, her or its obligations under this Agreement, each of such Shares that Shareholder shall be entitled to so vote with respect to the matters set forth in Section 1 hereof at any meeting of the shareholders of Company, and at any adjournment or postponement thereof, and in connection with any action of the shareholders of Company taken by written consent. Shareholder intends this proxy to be irrevocable and coupled with an interest hereafter until the termination of this Agreement pursuant to the terms of Section 7 hereof, and hereby revokes any proxy previously granted by Shareholder with respect to the Shares. This irrevocable proxy shall automatically terminate upon the termination of this Agreement.

Section 6. Specific Performance; Remedies; Attorneys’ Fees. Shareholder acknowledges that it is a condition to the willingness of Buyer to enter into the Merger Agreement that Shareholder execute and deliver this Agreement and that it will be impossible to measure in money the damage to Buyer if Shareholder fails to comply with the obligations imposed by this Agreement and that, in the event of any such failure, Buyer will not have an adequate remedy at law or in equity. Accordingly, Shareholder agrees that injunctive relief or other equitable remedy is the appropriate remedy for any such failure and will not oppose the granting of such relief on the basis that Buyer has an adequate remedy at law. Shareholder further agrees that Shareholder will not seek, and agrees to waive any requirement for, the securing or posting of a bond in connection with Buyer’s seeking or obtaining such equitable relief. In addition, after discussing the matter with Shareholder, Buyer shall have the right to inform any third party that Buyer reasonably believes to be, or to be contemplating, participating with Shareholder or receiving from Shareholder assistance in violation of this Agreement, of the terms of this Agreement and of the rights of Buyer hereunder, and that participation by any such persons with Shareholder in activities in violation of Shareholder’s agreement with Buyer set forth in this Agreement may give rise to claims by Buyer against such third party.

Section 7. Term of Agreement; Termination. The term of this Agreement shall commence on the date hereof. This Agreement may be terminated at any time prior to consummation of the transactions contemplated by the Merger Agreement by the written agreement of the parties hereto, and shall be automatically terminated upon termination of the Merger Agreement. Upon such termination, no party shall have any further obligations or liabilities hereunder; provided, however, that such termination shall not relieve any party from liability for any breach of this Agreement prior to such termination.

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Section 8. Entire Agreement; Amendments. This Agreement supersedes all prior agreements, written or oral, among the parties hereto with respect to the subject matter hereof and contains the entire agreement among the parties with respect to the subject matter hereof. This Agreement may not be amended, supplemented or modified, and no provisions hereof may be modified or waived, except by an instrument in writing signed by each party hereto. No waiver of any provisions hereof by either party shall be deemed a waiver of any other provision hereof by any such party, nor shall any such waiver be deemed a continuing waiver of any provision hereof by such party.

Section 9. Severability. In the event that any one or more provisions of this Agreement shall for any reason be held invalid, illegal or unenforceable in any respect, by any court of competent jurisdiction, such invalidity, illegality or unenforceability shall not affect any other provisions of this Agreement and the parties shall use their reasonable best efforts to substitute a valid, legal and enforceable provision which, insofar as practical, implements the purposes and intents of this Agreement.

Section 10. Capacity as Shareholder. This Agreement shall apply to Shareholder solely in his or her capacity as a shareholder of Company and it shall not apply in any manner to Shareholder in his or her capacity as a director, officer or employee of Company. Nothing contained in this Agreement shall be deemed to apply to, or limit in any manner, the obligations of Shareholder to comply with his or her fiduciary duties as a director or officer of Company, if applicable.

Section 11. Governing Law. This Agreement shall be governed by, and interpreted in accordance with, the internal, substantive laws of the State of Arkansas, without regard for the law or principles of conflict of laws.

Section 12. WAIVER OF JURY TRIAL. EACH OF THE PARTIES HERETO HEREBY IRREVOCABLY WAIVES TO THE FULLEST EXTENT PERMITTED BY APPLICABLE LAW ALL RIGHT TO TRIAL BY JURY IN ANY ACTION, PROCEEDING OR COUNTERCLAIM (WHETHER BASED ON CONTRACT, TORT OR OTHERWISE) DIRECTLY OR INDIRECTLY ARISING OUT OF OR RELATING TO THIS AGREEMENT OR THE TRANSACTIONS CONTEMPLATED HEREBY OR THE ACTIONS OF THE PARTIES IN THE NEGOTIATION, ADMINISTRATION, PERFORMANCE AND ENFORCEMENT OF THIS AGREEMENT. EACH OF THE PARTIES HERETO (A) CERTIFIES THAT NO REPRESENTATIVE OF ANY OTHER PARTY HAS REPRESENTED, EXPRESSLY OR OTHERWISE, THAT SUCH OTHER PARTY WOULD NOT, IN THE EVENT OF LITIGATION, SEEK TO ENFORCE THE FOREGOING WAIVER AND (B) ACKNOWLEDGES THAT IT AND THE OTHER PARTIES HAVE BEEN INDUCED TO ENTER INTO THIS AGREEMENT OR ANY OF THE TRANSACTIONS CONTEMPLATED HEREBY BY, AMONG OTHER THINGS, THE MUTUAL WAIVERS AND CERTIFICATIONS IN THIS SECTION 12 .

Section 13. Waiver of Appraisal Rights; Further Assurances. Provided that the Merger is consummated in compliance with the terms of the Merger Agreement, that the consideration offered pursuant to the Merger is not less than that specified in the Merger Agreement executed on or about the date hereof, and that this Agreement has not been terminated in accordance with its terms, to the extent permitted by applicable law, Shareholder hereby waives any rights of appraisal or rights to dissent from the Merger or demand fair value for his or her Shares in connection with the Merger, in each case, that Shareholder may have under applicable law. From time to time prior to the termination of this Agreement, at Buyer’s request and without further consideration, Shareholder shall execute and deliver such additional documents and take all such further action as may be reasonably necessary or desirable to effect the actions and consummate the transactions contemplated by this Agreement. Shareholder further

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agrees not to commence or participate in, and to take all actions necessary to opt out of any class in any class action with respect to, any claim, derivative or otherwise, against Buyer, Buyer Bank, Company, Company Bank or any of their respective successors relating to the negotiation, execution or delivery of this Agreement or the Merger Agreement or the consummation of the Merger.

Section 14. Disclosure. Shareholder hereby authorizes Company and Buyer to publish and disclose in any announcement or disclosure required by the Securities and Exchange Commission and in the Proxy Statement-Prospectus such Shareholder’s identity and ownership of the Shares and the nature of Shareholder’s obligations under this Agreement.

Section 15. Counterparts. This Agreement may be executed in two or more counterparts, each of which shall be deemed an original and all of which together shall constitute one instrument.

[Signature Page Follows.]

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IN WITNESS WHEREOF, the parties hereto have executed and delivered this Agreement as of the date first written above.

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