Results of Operations and Financial Condition. On October 21, 2026, Great Southern Bancorp, Inc. issued a press release reporting preliminary financial results for the three months ended September 30, 2026 . A copy of the press release, including unaudited financial information released as a part thereof, is attached as Exhibit 99.1 to this Current Report on Form 8-K and incorporated herein by reference.

Other Events. On September 16, 2026, Great Southern Bancorp, Inc., the holding company for Great Southern Bank, declared a $0.43 per common share dividend for the third quarter of the calendar year ending December 31, 2026. A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.

Results of Operations and Financial Condition. On July 15, 2026, Great Southern Bancorp, Inc. issued a press release reporting preliminary financial results for the quarter ended June 30, 2026. A copy of the press release, including unaudited financial information released as a part thereof, is attached as Exhibit 99.1 to this Current Report on Form 8-K and incorporated herein by reference.

Other Events. On June 17, 2026, Great Southern Bancorp, Inc., the holding company for Great Southern Bank, declared a $0.43 per common share dividend for the second quarter of the calendar year ending December 31, 2026. A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.

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Results of Operations and Financial Condition. On April 15, 2026, Great Southern Bancorp, Inc. issued a press release reporting preliminary financial results for the quarter ended March 31, 2026. A copy of the press release, including unaudited financial information released as a part thereof, is attached as Exhibit 99.1 to this Current Report on Form 8-K and incorporated herein by reference.

Other Events. On March 18, 2026, Great Southern Bancorp, Inc., the holding company for Great Southern Bank, declared a $0.43 per common share dividend for the first quarter of the calendar year ending December 31, 2026. A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.

Results of Operations and Financial Condition. On January 21, 2026, Great Southern Bancorp, Inc. issued a press release reporting preliminary financial results for the three months ended December 31, 2025. A copy of the press release, including unaudited financial information released as a part thereof, is attached as Exhibit 99.1 to this Current Report on Form 8-K and incorporated herein by reference.

Other Events. On December 17, 2025, Great Southern Bancorp, Inc., the holding company for Great Southern Bank, declared a $0.43 per common share dividend for the fourth quarter of the calendar year ending December 31, 2025. A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.

Results of Operations and Financial Condition. On October 15, 2025, Great Southern Bancorp, Inc. issued a press release reporting preliminary financial results for the three months ended September 30, 2025. A copy of the press release, including unaudited financial information released as a part thereof, is attached as Exhibit 99.1 to this Current Report on Form 8-K and incorporated herein by reference.

Other Events. On September 17, 2025, Great Southern Bancorp, Inc., the holding company for Great Southern Bank, declared a $0.43 per common share dividend for the third quarter of the calendar year ending December 31, 2025. A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.

Results of Operations and Financial Condition. On July 16, 2025, Great Southern Bancorp, Inc. issued a press release reporting preliminary financial results for the three months ended June 30, 2025. A copy of the press release, including unaudited financial information released as a part thereof, is attached as Exhibit 99.1 to this Current Report on Form 8-K and incorporated herein by reference.

Other Events. On June 18, 2025, Great Southern Bancorp, Inc., the holding company for Great Southern Bank, issued a press release announcing a quarterly dividend of $0.40 per common share for the second quarter of the calendar year ending December 31, 2025, payable on July 15, 2025, to stockholders of record on June 30, 2025. A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.

Results of Operations and Financial Condition. On April 16, 2025, Great Southern Bancorp, Inc. issued a press release reporting preliminary financial results for the quarter ended March 31, 2025. A copy of the press release, including unaudited financial information released as a part thereof, is attached as Exhibit 99.1 to this Current Report on Form 8-K and incorporated herein by reference.

Other Events. On March 19, 2025, Great Southern Bancorp, Inc., the holding company for Great Southern Bank, issued a press release announcing a quarterly dividend of $0.40 per common share for the first quarter of the calendar year ending December 31, 2025, payable on April 14, 2025, to stockholders of record on March 31, 2025. A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.

Results of Operations and Financial Condition. On January 21, 2025, Great Southern Bancorp, Inc. issued a press release reporting preliminary financial results for the fourth quarter ended December 31, 2024. A copy of the press release, including unaudited financial information released as a part thereof, is attached as Exhibit 99.1 to this Current Report on Form 8-K and incorporated herein by reference.

Other Events. On December 18, 2024, Great Southern Bancorp, Inc., the holding company for Great Southern Bank, issued a press release announcing a quarterly dividend of $0.40 per common share for the fourth quarter of the calendar year ending December 31, 2024, payable on January 14, 2025, to stockholders of record on December 30, 2024. A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.

Results of Operations and Financial Condition. On October 16, 2024, Great Southern Bancorp, Inc. issued a press release reporting preliminary financial results for the quarter ended September 30, 2024. A copy of the press release, including unaudited financial information released as a part thereof, is attached as Exhibit 99.1 to this Current Report on Form 8-K and incorporated herein by reference.

Other Events. On September 18, 2024, Great Southern Bancorp, Inc., the holding company for Great Southern Bank, issued a press release announcing a quarterly dividend of $0.40 per common share for the third quarter of the calendar year ending December 31, 2024, payable on October 15, 2024, to stockholders of record on September 30, 2024. A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.

Results of Operations and Financial Condition. On July 16, 2024, Great Southern Bancorp, Inc. issued a press release reporting preliminary financial results for the quarter ended June 30, 2024. A copy of the press release, including unaudited financial information released as a part thereof, is attached as Exhibit 99.1 to this Current Report on Form 8-K and incorporated herein by reference.

Other Events. On June 20, 2024, Great Southern Bancorp, Inc., the holding company for Great Southern Bank, issued a press release announcing a quarterly dividend of $0.40 per common share for the second quarter of the calendar year ending December 31, 2024, payable on July 16, 2024, to stockholders of record on July 1, 2024. A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.

Results of Operations and Financial Condition. On April 17, 2024, Great Southern Bancorp, Inc. issued a press release reporting preliminary financial results for the quarter ended March 31, 2024. A copy of the press release, including unaudited financial information released as a part thereof, is attached as Exhibit 99.1 to this Current Report on Form 8-K and incorporated herein by reference.

Other Events. On March 20, 2024, Great Southern Bancorp, Inc., the holding company for Great Southern Bank, issued a press release announcing a quarterly dividend of $0.40 per common share for the first quarter of the calendar year ending December 31, 2024, payable on April 16, 2024, to stockholders of record on April 2, 2024. A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.

Results of Operations and Financial Condition. On January 22, 2024, Great Southern Bancorp, Inc. issued a press release reporting preliminary financial results for the quarter and year ended December 31, 2023. A copy of the press release, including unaudited financial information released as a part thereof, is attached as Exhibit 99.1 to this Current Report on Form 8-K and incorporated herein by reference.

Director — Amelia 'Amy' Counts: Ms. Counts was appointed as a director of the Company and the Bank, effective January 1, 2024.