RESULTS OF OPERATIONS AND FINANCIAL CONDITION. On July 24, 2026, Southside Bancshares, Inc. issued a press release announcing its financial results for the second quarter ended June 30, 2026. A copy of the press release is attached as Exhibit 99.1 hereto and is hereby incorporated herein by reference. The information in this Current Report on Form 8-K, including the attached exhibit, is being furnished as provided in General Instruction B.2 to Form 8-K, to the Securities and Exchange Commissi…

RESULTS OF OPERATIONS AND FINANCIAL CONDITION. On April 30, 2026, Southside Bancshares, Inc. issued a press release announcing its financial results for the first quarter ended March 31, 2026. A copy of the press release is attached as Exhibit 99.1 hereto and is hereby incorporated herein by reference. The information in this Current Report on Form 8-K, including the attached exhibit, is being furnished as provided in General Instruction B.2 to Form 8-K, to the Securities and Exchange Commiss…

Director — Michael J. Bosworth: Mr. Bosworth is retiring from the Board due to a mandatory age requirement.

RESULTS OF OPERATIONS AND FINANCIAL CONDITION. On January 29, 2026, Southside Bancshares, Inc. issued a press release announcing its financial results for the fourth quarter and year ended December 31, 2025. A copy of the press release is attached as Exhibit 99.1 hereto and is hereby incorporated herein by reference. The information in this Current Report on Form 8-K, including the attached exhibit, is being furnished as provided in General Instruction B.2 to Form 8-K, to the Securities and E…

RESULTS OF OPERATIONS AND FINANCIAL CONDITION. On October 24, 2025, Southside Bancshares, Inc. issued a press release announcing its financial results for the third quarter ended September 30, 2025. A copy of the press release is attached as Exhibit 99.1 hereto and is hereby incorporated herein by reference. The information in this Current Report on Form 8-K, including the attached exhibit, is being furnished as provided in General Instruction B.2 to Form 8-K, to the Securities and Exchange C…

Other Events. On October 16, 2025, the Board of the Company increased it's authorization under the Company's current Stock Repurchase Plan (the “Plan”) by 1.0 million shares, for a total authorization to repurchase up to 2.0 million shares of the Company's common stock from time to time. Under the Plan, previously approved on July 20, 2023, the Company has purchased approximately 868,000 shares at an average price per share of $28.43, resulting in approximately 1.1 million shares remaining. R…

Director — Keith M. Donahoe, Jeb W. Jones, Raymond C. McKinney, CPA: The board size was increased and new directors were appointed.

CEO — Lee R. Gibson: The CEO is retiring with a pre-announced internal successor (the current President), representing an orderly succession rather than a sudden loss of leadership.

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant. The information set forth above under

Entry Into a Material Definitive Agreement. On August 14, 2025, Southside Bancshares, Inc. (the “Company”) completed its previously-announced public offering (the “Offering”) of $150,000,000 aggregate principal amount of its 7.00% Fixed-to-Floating Rate Subordinated Notes due 2035 (the “Notes”). The Notes were offered and sold pursuant to the Company’s registration statement on Form S-3ASR (Registration No. 333-271518) filed with the U.S. Securities and Exchange Commission (the “Commission”)…

Entry into a Material Definitive Agreement. On August 7, 2025, Southside Bancshares, Inc. (the “Company”) entered into an Underwriting Agreement (the “Underwriting Agreement”) among the Company, Southside Bank, a wholly-owned subsidiary of the Company, and Keefe, Bruyette & Woods, Inc., as representative to the several underwriters named therein (the “Underwriters”). Pursuant to the Underwriting Agreement, the Company agreed to issue and sell to the Underwriters $150,000,000 aggregate princip…

COO — Brian K. McCabe: The COO is retiring with a named internal successor (Mitchell Craddock) already identified to take over the role, indicating an orderly succession rather than a sudden loss of leadership.

RESULTS OF OPERATIONS AND FINANCIAL CONDITION. On July 25, 2025, Southside Bancshares, Inc. issued a press release announcing its financial results for the second quarter ended June 30, 2025. A copy of the press release is attached as Exhibit 99.1 hereto and is hereby incorporated herein by reference. The information in this Current Report on Form 8-K, including the attached exhibit, is being furnished as provided in General Instruction B.2 to Form 8-K, to the Securities and Exchange Commissi…

The filing discloses the approval of a new equity incentive plan, which is a compensatory arrangement rather than a change in management personnel.

RESULTS OF OPERATIONS AND FINANCIAL CONDITION. On April 29, 2025, Southside Bancshares, Inc. issued a press release announcing its financial results for the first quarter ended March 31, 2025. A copy of the press release is attached as Exhibit 99.1 hereto and is hereby incorporated herein by reference. The information in this Current Report on Form 8-K, including the attached exhibit, is being furnished as provided in General Instruction B.2 to Form 8-K, to the Securities and Exchange Commiss…

Director — Tony K. Morgan, John F. Sammons, Jr., Donald W. Thedford: The filing discloses the mandatory retirement of three long-serving directors due to age policy, which is a routine governance event rather than a sudden executive departure.

RESULTS OF OPERATIONS AND FINANCIAL CONDITION. On January 29, 2025, Southside Bancshares, Inc. issued a press release announcing its financial results for the fourth quarter and year ended December 31, 2024. A copy of the press release is attached as Exhibit 99.1 hereto and is hereby incorporated herein by reference. The information in this Current Report on Form 8-K, including the attached exhibit, is being furnished as provided in General Instruction B.2 to Form 8-K, to the Securities and E…

Director — George H. (Trey) Henderson, III: A director chose not to stand for re-election at the next annual meeting, which is a routine board turnover event with no indication of conflict or sudden loss.

Notice of Delisting or Failure to Satisfy a Continued Listing Rule or Standard; Transfer of Listing On November 4, 2024, Southside Bancshares, Inc. (the “ Company ”), acting pursuant to authorization from its Board of Directors, provided written notice to the Nasdaq Stock Market LLC (“ Nasdaq ”) of its determination to voluntarily withdraw the principal listing of the Company’s voting common stock, $1.25 par value per share (the “ Common Stock ”), from Nasdaq and transfer the listing to the N…

RESULTS OF OPERATIONS AND FINANCIAL CONDITION. On October 24, 2024, Southside Bancshares, Inc. issued a press release announcing its financial results for the third quarter ended September 30, 2024. A copy of the press release is attached as Exhibit 99.1 hereto and is hereby incorporated herein by reference. The information in this Current Report on Form 8-K, including the attached exhibit, is being furnished as provided in General Instruction B.2 to Form 8-K, to the Securities and Exchange C…

Chief Accounting Officer — April Pinkley: The filing discloses the internal promotion of three long-tenured employees to senior officer roles (CAO, CTO, CRO), which is a standard succession and talent development event rather than a departure.

RESULTS OF OPERATIONS AND FINANCIAL CONDITION. On July 25, 2024, Southside Bancshares, Inc. issued a press release announcing its financial results for the second quarter ended June 30, 2024. A copy of the press release is attached as Exhibit 99.1 hereto and is hereby incorporated herein by reference. The information in this Current Report on Form 8-K, including the attached exhibit, is being furnished as provided in General Instruction B.2 to Form 8-K, to the Securities and Exchange Commissi…

President — Keith Donahoe: The filing announces the internal promotion of Keith Donahoe from Regional President to President of the Company, which is a succession event rather than a departure.

RESULTS OF OPERATIONS AND FINANCIAL CONDITION. On April 25, 2024, Southside Bancshares, Inc. issued a press release announcing its financial results for the first quarter ended March 31, 2024. A copy of the press release is attached as Exhibit 99.1 hereto and is hereby incorporated herein by reference. The information in this Current Report on Form 8-K, including the attached exhibit, is being furnished as provided in General Instruction B.2 to Form 8-K, to the Securities and Exchange Commiss…

Chief Lending Officer — Tim Alexander: The Chief Lending Officer is retiring with a named successor (Curtis Burchard) already identified to take over the role, indicating an orderly succession rather than a sudden loss of leadership.