Prosperity Bancshares Inc美股招股说明书(2025-12-18版)

MERGER PROPOSED—YOUR VOTE IS VERY IMPORTANT Dear Shareholders of Southwest Bancshares, Inc.: On Thursday, January 22, 2026, a special meeting of the shareholders of Southwest Bancshares, Inc. (“SWBI”) will be held in person to vote on aproposal to merge with Prosperity Bancshares, Inc. (“Prosperity”), a Texas corporation and the parent company of Prosperity Bank. On September30,2025, Prosperity and SWBI entered into an Agreement and Plan of Merger (as amended from time to time, the “merger agreement”) that provides for themerger of SWBI with and into Prosperity, with Prosperity as the surviving corporation (the “merger”). Immediately following the completion of themerger, Texas Partners Bank, a Texas banking association and a wholly owned bank subsidiary of SWBI, will merge with and into Prosperity Bank, aTexas banking association and a wholly owned bank subsidiary of Prosperity, with Prosperity Bank as the surviving bank (the “bank merger”). If the merger is completed, all shares of SWBI 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 4,062,520 shares of Prosperity common stockplusthe number of shares ofProsperity common stock (rounded down to the nearest whole share) equal to the product of 0.6469 (the “exchange ratio”)multiplied bythe aggregatenumber of shares of SWBI common stock issued and outstanding as of immediately prior to the effective time as a result of any exercise of any SWBIoption or SWBI warrant after the date of the merger agreement (the “aggregate stock consideration”), as such number of shares of Prosperity commonstock may be reduced pursuant to the terms of the merger agreement. The aggregate stock consideration will be reduced if the equity capital of SWBI, ascalculated under the merger agreement, is less than (i) $188,000,000plus(ii)the aggregate exercise price paid to SWBI in respect of all exercises ofSWBI options or SWBI warrants between the date of the merger agreement and the closing of the merger (the “minimum equity capital”). Because ofthe possibility of a downward adjustment to the aggregate stock consideration, the number of shares each SWBI shareholder receives in the merger maychange. For illustrative purposes only, if the merger occurs and assuming (i)there are 6,278,720 shares of SWBI common stock issued and outstanding atthe closing of the merger (including 150,186 shares of SWBI common stock issued and outstanding pursuant to SWBI restricted stock awards andassuming there has not been any exercise of SWBI options or SWBI warrants after the date of the merger agreement), (ii) the SWBI equity capital on theclosing date, as calculated pursuant to the terms of the merger agreement, is equal to or greater than the minimum equity capital and (iii)the price pershare of Prosperity common stock received in the merger is equal to $72.83, which was the closing price per share of Prosperity common stock onDecember 12, 2025, then holders of SWBI common stock will receive 4,062,520 shares of Prosperity common stock with a value of $47.12 (beforeadjusting for fractional shares) for each share of SWBI common stock. If the merger is completed, assuming no downward adjustment to the aggregate stock consideration, based on the number of shares of Prosperityand SWBI common stock outstanding as of the close of business on the record date, and based on the number of shares of Prosperity common stockexpected to be issued in the merger, existing Prosperity shareholders would own approximately 95.8% of Prosperity’s common stock immediatelyfollowing completion of the merger and former SWBI shareholders would own approximately 4.2%. Giving effect to the closing of Prosperity’s previously announced acquisition of American Bank Holding Corporation (“ABHC”), assuming nodownward adjustment to the aggregate merger consideration payable to the shareholders of ABHC in connection with such acquisition, based on thenumber of shares of Prosperity and Table of Contents SWBI common stock outstanding as of the close of business on the record date, and based on the number of shares of Prosperity common stockexpected to be issued in the merger, the former holders of SWBI common stock, as a group, are estimated to own approximately 4.0% of the fullydiluted shares of Prosperity immediately after the merger. Prosperity’s common stock is listed on the New York Stock Exchange under the symbol “PB,” and the closing price of Prosperity common stockon December 12, 2025, was $72.83 per share. SWBI will hold a special meeting of its shareholders in connection with the merger. At the SWBI special meeting, SWBI 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“SWBI merger proposal”) and (ii)a proposal to adjourn or postpone the SWBI special meeting, if necessary or appropriate, to