PROSPERITY BANCSHARES INC

c. Insider Trading Arrangements and Policies.

On July 30, 2024, Ned Holmes, a member of Bancshares’ Board of Directors, adopted a Rule 10b5-1 trading plan (“Rule 10b5-1 Plan”) intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) under the Exchange Act. The Rule 10b5-1 Plan covers shares of Bancshares common stock owned by (i) by Mr. Holmes directly, (ii) a profit sharing plan for Mr. Holmes, and (iii) a trust for the benefit of Mr. Holmes’ daughter, for which he is the trustee. Among other things, the Rule 10b5-1 Plan provides for the sale of up to 52,000 shares of Bancshares common stock held directly by Mr. Holmes, up to 52,000 shares of Bancshares common stock held by the profit sharing plan and up to 10,400 shares of Bancshares common stock held by the trust. In each case, trades under the Rule 10b5-1 Plan will be made during the period beginning on the later of (i) November 13, 2024, and (ii) the third trading day following disclosure of the Company’s financial results on Form 10-Q for the quarter ended September 30, 2024, and ending on November 30, 2026, subject to earlier termination in accordance with the terms of the Rule 10b5-1 Plan and applicable laws, rules and regulations.

During the three months ended September 30, 2024, no other director or officer adoptedor terminatedany “Rule 10b5-1 trading arrangement” or “non-Rule 10b5-1 trading arrangement” (as each term is defined in Item 408(a) of Regulation S-K) with respect to Bancshares common stock.