Asset Transaction, Corporate Action, Changes in Control, Amendments to Bylaws, Management Change/Compensation (Form 8-K)

On July 1, 2026, Stellar Bancorp, Inc., a Texas corporation ("Stellar"), merged (the "Merger") with and into Prosperity Bancshares, Inc., a Texas corporation ("Prosperity"), with Prosperity continuing as the surviving corporation (the "Surviving Corporation") in the Merger pursuant to the Agreement and Plan of Merger, dated as of January 27, 2026 (the "Merger Agreement"), by and between Prosperity and Stellar.

Immediately following the Merger, Stellar Bank, a Texas banking association and wholly owned subsidiary of Stellar, merged with and into Prosperity Bank, a Texas banking association and wholly owned subsidiary of Prosperity (the "Bank Merger" and together with the Merger, the "Transactions"), with Prosperity Bank continuing as the surviving bank in the Bank Merger.

Pursuant to the Merger Agreement, at the effective time of the Merger (the "Effective Time"), each share of common stock, par value $0.01 per share, of Stellar ("Stellar Common Stock") outstanding immediately prior to the Effective Time, other than certain shares held by Prosperity or Stellar, was converted into the right to receive (i) 0.3803 shares of common stock (the "Exchange Ratio"), par value $1.00 per share, of Prosperity ("Prosperity Common Stock"), (ii) an amount in cash equal to $11.36 (the "Per Share Cash Consideration") ((i) and (ii) together, the "Per Share Merger Consideration") and (iii) cash in lieu of fractional shares.

Pursuant to the Merger Agreement, at the Effective Time:

The foregoing description of the Transactions and the Merger Agreement does not purport to be complete and is qualified in its entirety by reference to the full text of the Merger Agreement, a copy of which is filed as Exhibit 2.1 and incorporated herein by reference.

On June 30, 2026, Stellar notified the New York Stock Exchange (the "NYSE") of the consummation of the Merger and requested that the NYSE (i) suspend trading of Stellar Common Stock prior to the opening of trading on July 1, 2026, (ii) withdraw Stellar Common Stock from listing on the NYSE prior to the opening of trading on July 1, 2026, and (iii) file with the Securities and Exchange Commission (the "SEC") notifications of delisting of Stellar Common Stock on Form 25 and deregistration under Section 12(b) of the Securities Exchange Act of 1934, as amended (the "Exchange Act"). As a result, Stellar Common Stock will no longer be listed on the NYSE.

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Additionally, Prosperity, as successor to Stellar, intends to file with the SEC a certification on Form 15 requesting the deregistration of Stellar Common Stock under Section 12(g) of the Exchange Act and the suspension of Stellar's reporting obligations under Sections 13 and 15(d) of the Exchange Act as promptly as practicable.

The information set forth under Item 2.01 of this Current Report on Form 8-K is incorporated by reference into this Item 3.01.

As of the Effective Time, each holder of a certificate or book-entry share representing any shares of Stellar Common Stock ceased to have any rights with respect thereto, except the right to receive the consideration as described above and subject to the terms and conditions set forth in the Merger Agreement.

The information set forth under Items 2.01, 3.01, 5.01 and 5.03 of this Current Report on Form 8-K is incorporated by reference into this Item 3.03.

The information set forth under Items 2.01, 3.01, 3.03 and 5.02 of this Current Report on Form 8-K is incorporated by reference into this Item 5.01.

As of the Effective Time, and pursuant to the terms of the Merger Agreement, Stellar's directors and executive officers ceased serving as directors and executive officers of Stellar. In addition, as of the Effective Time and in accordance with the Merger Agreement, Robert R. Franklin, Jr. and Joseph B. Swinbank, each of whom was a member of the board of directors of Stellar immediately prior to the consummation of the Merger, were appointed to the board of directors of Prosperity.

At the Effective Time, the Second Amended and Restated Certificate of Formation and Amended and Restated Bylaws of Stellar ceased to be in effect by operation of law. As a result of the Merger, Prosperity's Amended and Restated Articles of Incorporation, as amended, and Amended and Restated Bylaws, copies of which are included as Exhibits 3.1, 3.2 and 3.3 hereto, respectively, and incorporated by reference herein, continued in effect as the governing documents of the Surviving Corporation.

The information set forth under Item 2.01 of this Current Report on Form 8-K is incorporated by reference into this Item 5.03.