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, AMERICAN STATE FINANCIAL CORPORATION AND THE PROPOSED TRANSACTION.In connection with the proposed merger of East Texas Financial Services, Inc. into Prosperity Bancshares, and the proposed merger of The Bank Arlington into Prosperity Bank, Prosperity Bancshares has filed with the Securities and Exchange Commission registration statements on Form S-4 to register the shares of Prosperity's common stock to be issued to the stockholders of East Texas Financial Services and the shareholders of The Bank Arlington. Each registration statement includes a proxy statement/prospectus which was sent to the stockholders of East Texas Financial Services and the shareholders of The Bank Arlington, as applicable, 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 FILED WITH THE SECURITIES AND EXCHANGE COMMISSION IN CONNECTION WITH THE PROPOSED TRANSACTIONS BECAUSE THEY CONTAIN IMPORTANT INFORMATION ABOUT PROSPERITY, EAST TEXAS FINANCIAL SERVICES, THE BANK ARLINGTON AND THE PROPOSED TRANSACTIONS. Investors and security holders may obtain free copies of these documents through the website maintained by the Securities and Exchange Commission at http://www.sec.gov. Documents filed with the SEC by Prosperity will be 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. Prosperity's telephone number is (281) 269-7199. "Safe Harbor" Statement under the Private Securities Litigation Reform Act of 1995: This release contains forward-looking statements within the meaning of the securities laws that are based on current expectations, assumptions, estimates and projections about Prosperity and its subsidiaries. These forward-looking statements are not guarantees of future performance and are subject to risks and uncertainties, many of which are outside of Prosperity's control, that may cause actual results to differ materially from those expressed or implied by the forward-looking statements. These risks and uncertainties include but are not limited to whether Prosperity can: successfully identify acquisition targets and integrate the businesses of acquired companies and banks; continue to sustain its current internal growth rate or total growth rate; provide products and services that appeal to its customers; continue to have access to debt and equity capital markets; and achieve its sales objectives. Other risks include, but are not limited to: the possibility that credit quality could deteriorate; actions of competitors; changes in laws and regulations (including changes in governmental interpretations of regulations and changes in accounting standards); a deterioration or downgrade in the credit quality and credit agency ratings of the securities in Prosperity's securities portfolio; customer and consumer demand, including customer and consumer response to marketing; effectiveness of spending, investments or programs; fluctuations in the cost and availability of supply chain resources; economic conditions, including currency rate fluctuations and interest rate fluctuations; weather; and the stock price volatility associated with "small-cap" companies. These and various other factors are discussed in Prosperity's Annual Report on Form 10-K for the year ended December 31, 2010 and other reports and statements Prosperity has filed with the SEC. Copies of the SEC filings for Prosperity Bancshares ® may be downloaded from the Internet at no charge from www.prosperitybanktx.com . SOURCE Prosperity Bancshares, Inc.