Executive Change

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934   May 15, 2026 Date of Report (Date of earliest event reported) TRUSTMARK CORP ORATION (Exact name of registrant as specified in its charter)   Mississippi   000-03683   64-0471500 (State or other jurisdiction of incorporation)   (Commission File Number)   (IRS Employer Identification No.)   248 East Capitol Street , Jackson , Mississippi   39201 (Address of principal executive offices)   (Zip Code)       Registrant’s telephone number, including area code:   ( 601 ) 208-5111   Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:   ☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))   Securities registered Pursuant to Section 12(b) of the Act: Title of each class Trading Symbol(s) Name of each exchange on which registered Common Stock, no par value TRMK Nasdaq  Global Select Market   Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (17 CFR §230.405) or Rule 12b-2 of the Securities Exchange Act of 1934 (17 CFR §240.12b-2).   Emerging growth company ☐ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐         Item 5.02(b). Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.   On May 15, 2026, Wayne A. Stevens notified the Boards of Directors of Trustmark Corporation (the "Company") and its wholly owned subsidiary, Trustmark Bank (the “Bank”), of his intention to retire as President - Retail Banking of the Bank, effective as of July 3, 2026.   In connection with his retirement, the Human Resources Committee of the Company’s Board of Directors approved the acceleration of vesting of his unvested time-based restricted stock units. Otherwise, Mr. Stevens will not receive any severance or other compensatory payments in connection with his departure, other than payment of earned but unpaid wages and other amounts due in the ordinary course and consistent with Company policy.   Trustmark appreciates the distinguished service of Mr. Stevens, who has served as an associate of Trustmark Bank beginning in 1986, and as an Executive Officer since 2009. Over the last 40 years, Mr. Stevens has made significant contributions to the growth and expansion of the organization. Trustmark expresses its sincere gratitude for his commitment to our customers, associates, and the communities we serve. Item 9.01. Financial Statements and Exhibits. (d) Exhibits Exhibit Number   Description of Exhibits 104   Cover Page Interactive Data File (embedded within the Inline XBRL document)       SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.   TRUSTMARK CORPORATION BY:   /s/ Joseph E. Bond     Joseph E. Bond     Treasurer and Principal Financial Officer       DATE:   May 19, 2026