Prosperity Bancshares Inc美股招股说明书(2025-09-30版)

MERGER PROPOSED—YOUR VOTE IS VERY IMPORTANT Dear Shareholders of American Bank Holding Corporation: On November3, 2025 a special meeting of the shareholders of American Bank Holding Corporation (“ABHC”) will be held in person to vote on aproposal to merge with Prosperity Bancshares, Inc. (“Prosperity”), aTexas corporation and the parent company of Prosperity Bank. On July17, 2025,Prosperity and ABHC entered into an Agreement and Plan of Merger (as amended from time to time, the “merger agreement”) that (i)provides for themerger of ABHC with and into Prosperity, with Prosperity as the surviving corporation (the “merger”) and (ii)contemplates that immediately followingthe merger, American Bank, National Association, a wholly owned subsidiary of ABHC, will merge with and into Prosperity Bank, with Prosperity Bankas the surviving entity. If the merger is completed, all shares of ABHC common stock issued and outstanding immediately prior to the effective time of the merger will beconverted into the right to receive, without interest, an aggregate of 4,439,981 shares of Prosperity common stock (the “aggregate stock consideration”)as such number of shares of Prosperity common stock may be reduced pursuant to the terms of the merger agreement. The aggregate stock considerationwill be reduced if the equity capital of ABHC, as calculated under the merger agreement, on the closing date is less than $173,000,000. Because of thepossibility of an adjustment to the aggregate stock consideration, the number of shares each ABHC shareholder receives in the merger may change. For illustration purposes only, if the merger occurs and assuming (i)there are 995,467shares of ABHC common stock issued and outstanding atthe closing of the merger (including 21,918shares of ABHC common stock issued and outstanding pursuant to ABHC restricted stock awards), (ii)ABHC’s equity capital on the closing date, as calculated under the merger agreement, is equal to or greater than $173,000,000, and (iii)the price pershare of Prosperity common stock received in the merger is equal to $65.97, which was the closing price per share of Prosperity common stock onSeptember 29, 2025, then holders of ABHC common stock (including shares of ABHC common stock issued and outstanding pursuant to ABHCrestricted stock awards) will receive 4,439,981 shares of Prosperity common stock with a value of $294.24 (prior to adjustments for fractional shares)for each share of ABHC common stock they own. If the merger is completed, existing Prosperity shareholders would own approximately 95.5% of Prosperity’s common stock immediatelyfollowing completion of the merger and former ABHC shareholders would own approximately 4.5%. Prosperity’s common stock is listed on the NewYork Stock Exchange under the symbol “PB,” and the closing price of Prosperity common stock on September 29, 2025 was $65.97 per share. ABHC will hold a special meeting of its shareholders in connection with the merger. At the ABHC special meeting, ABHC shareholders will beasked to consider and vote on (i)a proposal to approve the merger agreement and the transactions contemplated thereby, including the merger (the“ABHC merger proposal”) and (ii)a proposal to adjourn or postpone the ABHC special meeting, if necessary or appropriate, to solicit additional proxiesif there are insufficient votes at the time of such adjournment or postponement to approve the ABHC merger proposal (the “ABHC adjournmentproposal”). Prosperity and ABHC cannot complete the merger unless the holders of ABHC common stock approve the ABHC merger proposal. ABHC’sboard of directors (the “ABHC board of directors”) is providing this proxy statement/prospectus to solicit ABHC shareholders’ proxy to vote inconnection with the ABHC merger proposal and the ABHC adjournment proposal. This document is also a prospectus that is being delivered to holdersof ABHC common stock because, in connection with the merger, Prosperity is offering shares of Prosperity common stock to holders of ABHC commonstock. Table of Contents The ABHC special meeting will be held in person on November3, 2025, at 10:00 a.m., Central Time, at the Omni Corpus Christi Hotel (AransasRoom), 900 North Shoreline Boulevard, Corpus Christi, Texas 78401. ABHC shareholders, your vote is very important. To ensure your representation at the ABHC special meeting, please complete, sign, date and return the enclosed proxy. Sending in yourproxy will not prevent you from voting your shares in person at the ABHC special meeting, since you may revoke your proxy at any time beforeit is voted. The ABHC board of directors unanimously approved the merger agreement and the transactions contemplated thereby, including themerger, and recommends that ABHC shareholders vote “FOR” the ABHC merger proposal and “FOR” the ABHC adjournment proposal. This document contains a more complete description of the ABHC special meeting, the merger, the documents related to the merger and otherrelated