Fourth Quarter Highlights

3 Important Information Additional Information about the First Bancshares Merger and Where to Find It In connection with the proposed merger of First Bancshares into Prosperity, Prosperity has filed with the SEC a registration statement on Form S-4 to register the shares of Prosperity common stock to be issued to the shareholders of First Bancshares. The registration statement includes a preliminary proxy statement/prospectus. The definitive proxy statement/prospectus will be sent to the shareholders of First Bancshares seeking their approval of the proposed transaction. WE URGE INVESTORS AND SECURITY HOLDERS TO READ THE REGISTRATION STATEMENT ON FORM S-4, THE PROXY STATEMENT/PROSPECTUS INCLUDED WITHIN THE REGISTRATION STATEMENT ON FORM S-4 AND ANY OTHER RELEVANT DOCUMENTS TO BE FILED WITH THE SECURITIES AND EXCHANGE COMMISSION IN CONNECTION WITH THE PROPOSED TRANSACTION BECAUSE THEY CONTAIN IMPORTANT INFORMATION ABOUT PROSPERITY, FIRST BANCSHARES AND THE PROPOSED TRANSACTION. Investors and security holders may obtain free copies of these documents through the website maintained by the SEC at http://www.sec.gov. You will also be able to obtain these documents, when they are filed, free of charge, from Prosperity at http://www.prosperitybankusa.com. Copies of the proxy statement/prospectus can also be obtained, when it becomes available, free of charge, by directing a request by telephone or mail to Prosperity Bancshares, Inc., Prosperity Bank Plaza, 4295 San Felipe, Houston, Texas 77027 Attn: Investor Relations, (281) 269-7199 or to First Bancshares of Texas, Inc., 310 West Wall Street, Suite 1200, Midland, Texas 79701, Attention: Ken Burgess, (844) 322-8392. Additional Information about the Lone Star Merger and Where to Find It In connection with the proposed merger of Lone Star into Prosperity, Prosperity has filed with the SEC a registration statement on Form S-4 to register the shares of Prosperity common stock to be issued to the shareholders of Lone Star. The registration statement includes a proxy statement/prospectus. The definitive proxy statement/prospectus will be sent to the shareholders of Lone Star seeking their approval of the proposed transaction. WE URGE INVESTORS AND SECURITY HOLDERS TO READ THE REGISTRATION STATEMENT ON FORM S-4, THE PROXY STATEMENT/PROSPECTUS INCLUDED WITHIN THE REGISTRATION STATEMENT ON FORM S-4 AND ANY OTHER RELEVANT DOCUMENTS TO BE FILED WITH THE SECURITIES AND EXCHANGE COMMISSION IN CONNECTION WITH THE PROPOSED TRANSACTION BECAUSE THEY CONTAIN IMPORTANT INFORMATION ABOUT PROSPERITY, LONE STAR AND THE PROPOSED TRANSACTION. Investors and security holders may obtain free copies of these documents through the website maintained by the SEC at http://www.sec.gov. You will also be able to obtain these documents, when they are filed, free of charge, from Prosperity at http://www.prosperitybankusa.com. Copies of the proxy statement/prospectus can also be obtained, when it becomes available, free of charge, by directing a request by telephone or mail to Prosperity Bancshares, Inc., Prosperity Bank Plaza, 4295 San Felipe, Houston, Texas 77027 Attn: Investor Relations, (281) 269-7199 or to Lone Star State Bancshares, Inc., 6220 Milwaukee Avenue, Lubbock, Texas 79424, Attention: Alan Lackey, (806) 771-7717. Participants in the Solicitation Prosperity, First Bancshares and their respective directors and executive officers may be deemed to be participants in the solicitation of proxies from the shareholders of First Bancshares in connection with the proposed transaction. Certain information regarding the interests of these participants and a description of their direct and indirect interests, by security holdings or otherwise, is included in the registration statement and proxy statement/prospectus regarding the proposed transaction and other relevant materials to be filed with the SEC when they become available. Prosperity, Lone Star and their respective directors and executive officers may be deemed to be participants in the solicitation of proxies from the shareholders of Lone Star in connection with the proposed transaction. Certain information regarding the interests of these participants and a description of their direct and indirect interests, by security holdings or otherwise, is included in the registration statement and proxy statement/prospectus regarding the proposed transaction and other relevant materials to be filed with the SEC when they become available. Additional information about Prosperity and its directors and executive officers may be found in the definitive proxy statement of Prosperity relating to its 2022 Annual Meeting of Shareholders filed with the SEC on March 14, 2022, and other documents filed by Prosperity with the SEC. These documents can be obtained free of charge from the sources described above. No Offer or Solicitation This communication is for informational purposes only and is not intended to and does not constitute an offer to subscribe for, buy or sell, or the solicitation of an offer to subscribe for, buy or sell, or an invitation to subscribe for, buy or sell any securities or a solicitation of any vote or approval in any jurisdiction, nor shall there be any sale, issuance or transfer of securities in any jurisdiction in which such offer, invitation, sale or solicitation would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. No offer of securities shall be made except by means of a prospectus meeting the requirements of Section 10 of the Securities Act of 1933, as amended, and otherwise in accordance with applicable law. PB LISTED NYSE

View entire presentation