Changes in Control of the Registrant. 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

Notice of Delisting or Failure to Satisfy a Continued Listing Rule or Standard; Transfer of Listing. 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 Commissi…

Completion of Acquisition or Disposition of Assets. 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 Merge…

All directors and executive officers of Stellar ceased their roles due to a merger.

Material Modification to Rights of Security Holders. 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…

Other Events. Declaration of Dividend On May 20, 2026, the Stellar Bancorp, Inc. issued a press release announcing that on May 20, 2026, its Board of Directors declared a quarterly cash dividend in the amount of $0.15 per share of common stock p ayable on June 26, 2026, to the shareholders of record at the close of business on June 15, 2026. A copy of the press release is attached hereto as Exhibit 99.1 and is incorporated herein by reference, including the cautionary language regarding forwa…

Other Events. As announced on January 28, 2026, Stellar Bancorp, Inc., a Texas corporation (“Stellar” or the “Company”), entered into an Agreement and Plan of Merger, dated January 27, 2026 (the “Merger Agreement”), with Prosperity Bancshares, Inc., a Texas corporation (“Prosperity”), pursuant to which Stellar will merge with and into Prosperity (the “Merger”), with Prosperity as the surviving corporation in the Merger. Immediately following the Merger, Stellar’s wholly owned banking subsidia…

Results of Operations and Financial Condition. On April 28, 2026 Stellar Bancorp, Inc. (the “Company”) issued a press release announcing its financial results for the first quarter of 2026. A copy of the press release is furnished as Exhibit 99.1 hereto, respectively, and incorporated herein by reference. In accordance with General Instruction B.2 to Form 8-K, the information furnished in this Item 2.02, Exhibit 99.1 of this Current Report on Form 8-K shall not be deemed “filed” for purposes…

Other Events. Declaration of Dividend On February 25, 2026, the Stellar Bancorp, Inc. issued a press release announcing that on February 25, 2026, its Board of Directors declared a quarterly cash dividend in the amount of $0.15 per share of common stock p ayable on March 31, 2026, to the shareholders of record at the close of business on March 16, 2026. A copy of the press release is attached hereto as Exhibit 99.1 and is incorporated herein by reference, including the cautionary language reg…

Entry into a Material Definitive Agreement. Merger Agreement On January 27, 2026, Stellar Bancorp, Inc., a Texas corporation (“Stellar”), entered into an Agreement and Plan of Merger (the “Merger Agreement”) with Prosperity Bancshares, Inc., a Texas corporation (“Prosperity”). The Merger Agreement provides that, upon the terms and subject to the conditions set forth therein, Stellar will merge with and into Prosperity (the “Merger”), with Prosperity continuing as the surviving corporation in…

Regulation FD Disclosure. On January 28, 2026, Stellar Bancorp, Inc., a Texas corporation (“Stellar”), and Prosperity Bancshares, Inc., a Texas corporation (“Prosperity”), issued a joint press release announcing the execution of an Agreement and Plan of Merger (the “Merger Agreement”), dated as of January 27, 2026, by and between Prosperity and Stellar, pursuant to which, upon the terms and subject to the conditions set forth therein, Stellar will merge with and into Prosperity (the “Merger”)…

and Exhibit 99.1 of this Current Report on Form 8-K shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that section, and such information shall not be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, except as shall be expressly set forth by specific reference in such filing.

Other Events. Declaration of Dividend On November 20, 2025, the Company issued a press release announcing that on November 20, 2025, its Board of Directors declared a quarterly cash dividend in the amount of $0.15 per share of common stock p ayable on December 31, 2025, to the shareholders of record at the close of business on December 31, 2025. This is an increase of $0.01 per share from the previous quarterly dividend of $0.14 per common share. A copy of the press release is attached hereto…

Results of Operations and Financial Condition. On October 24, 2025 Stellar Bancorp, Inc. (the “Company”) issued a press release announcing its financial results for the third quarter of 2025. A copy of the press release, as well as a copy of the accompanying earnings presentation, are furnished as Exhibit 99.1 and Exhibit 99.2 hereto, respectively, and incorporated herein by reference. In accordance with General Instruction B.2 to Form 8-K, the information furnished in this Item 2.02, Exhibit…

Other Events. Declaration of Dividend On August 28, 2025, the Company issued a press release announcing that on August 27, 2025, its Board of Directors declared a quarterly cash dividend in the amount of $0.14 per share of common stock p ayable on September 30, 2025, to the shareholders of record at the close of business on September 15, 2025. A copy of the press release is attached hereto as Exhibit 99.1 and is incorporated herein by reference, including the cautionary language regarding for…

Results of Operations and Financial Condition. On July 25, 2025 Stellar Bancorp, Inc. (the “Company”) issued a press release announcing its financial results for the second quarter of 2025. A copy of the press release, as well as a copy of the accompanying earnings presentation, are furnished as Exhibit 99.1 and Exhibit 99.2 hereto, respectively, and incorporated herein by reference. In accordance with General Instruction B.2 to Form 8-K, the information furnished in this Item 2.02, Exhibit 9…

Director — William E. Wilson, Jr.: A director resigned from the board without any stated disagreement, representing a standard board turnover event rather than a loss of senior executive management.

Other Events. Declaration of Dividend On May 22, 2025, the Company issued a press release announcing that on May 21, 2025, its Board of Directors declared a quarterly cash dividend in the amount of $0.14 per share of common stock p ayable on June 30, 2025, to the shareholders of record at the close of business on June 16, 2025. A copy of the press release is attached hereto as Exhibit 99.1 and is incorporated herein by reference, including the cautionary language regarding forward-looking sta…

The filing discloses the adoption of a new Executive Severance Plan, which is a compensatory arrangement rather than an actual change in management personnel.

Results of Operations and Financial Condition. On April 25, 2025 Stellar Bancorp, Inc. (the “Company”) issued a press release announcing its financial results for the first quarter of 2025. A copy of the press release, as well as a copy of the accompanying earnings presentation, are furnished as Exhibit 99.1 and Exhibit 99.2 hereto, respectively, and incorporated herein by reference. In accordance with General Instruction B.2 to Form 8-K, the information furnished in this Item 2.02, Exhibit 9…

Other Events. Share Repurchase Program On April 23, 2025, Stellar Bancorp, Inc. (the “Company”) issued a press release announcing that the Company’s Board of Directors authorized a new share repurchase program under which the Company may repurchase up to $65 million of the Company’s common stock through May 31, 2026. Membership in Federal Reserve System The press release issued by the Company on April 23, 2025 also announced that Stellar Bank, the wholly-owned subsidiary of the Company, compl…

Results of Operations and Financial Condition. The Company’s Annual Report on Form 10-K filed on March 3, 2025 (the “Annual Report”) contains updated information with respect to the Company’s results of operations for the year ended December 31, 2024. The Annual Report updates the information included in Exhibit 99.1 - Q4 2024 Earnings Release – and Exhibit 99.2 – Q4 2024 Earnings Presentation - furnished as exhibits to the Original Form 8-K. Prior to the issuance of the audited financial sta…

Other Events. Declaration of Dividend The Company issued a press release announcing that on February 26, 2025, its Board of Directors declared a quarterly cash dividend in the amount of $0.14 per share of common stock p ayable on March 31, 2025, to the shareholders of record at the close of business on March 17, 2025. A copy of the press release is attached hereto as Exhibit 99.1 and is incorporated herein by reference, including the cautionary language regarding forward-looking statements.

Results of Operations and Financial Condition. On January 30, 2025 Stellar Bancorp, Inc. (the “Company”) issued a press release announcing its financial results for the fourth quarter of 2024. A copy of the press release, as well as a copy of the accompanying earnings presentation, are furnished as Exhibit 99.1 and Exhibit 99.2 hereto, respectively, and incorporated herein by reference. In accordance with General Instruction B.2 to Form 8-K, the information furnished in this Item 2.02, Exhibi…

Director — Michael A. Havard: The director is retiring from the board at the end of his term without any disagreement, which is a routine and orderly succession event.