Results of Operations

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   April 28, 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 2.02. Results of Operations and Financial Condition. On April 28, 2026, Trustmark Corporation issued a press release announcing its financial results for the period ended March 31, 2026. A copy of this press release and the accompanying financial statements and slide presentation are attached hereto as Exhibits 99.1 and 99.2 to this report and incorporated herein by reference.     Item 9.01. Financial Statements and Exhibits. (d) Exhibits Exhibit Number   Description of Exhibits 99.1   Press release announcing financial results for the period ended March 31, 2026 99.2   Investor slide presentation for the period ended March 31, 2026 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/ Thomas C. Owens     Thomas C. Owens     Treasurer and Principal Financial Officer       DATE:   April 28, 2026