Stellar Bancorp (STEL) investor relations material

Executive summary

• A proposed merger transaction between Prosperity Bancshares, Inc. and Stellar Bancorp, Inc. is underway, with the issuance of Prosperity common stock to Stellar shareholders as part of the agreement.

• The registration statement for the transaction was declared effective on April 21, 2026, and the proxy statement/prospectus was mailed to shareholders starting April 23, 2026.

• Forward-looking statements address anticipated benefits, synergies, and future opportunities, but highlight significant risks and uncertainties that could affect outcomes.

Voting matters and shareholder proposals

• Shareholders are being solicited to vote on the proposed merger transaction, with proxy materials distributed for this purpose.

• Approval by Stellar shareholders is a key condition for the transaction to proceed.

Board of directors and corporate governance

• Information about directors and executive officers, including their stock ownership, is disclosed in referenced SEC filings and the proxy statement.

• Certain directors, executive officers, and employees of both companies may be deemed participants in the proxy solicitation.