Reg FD Disclosure

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 November 12, 2025 Date of Report (Date of earliest event reported)       TRUSTMARK CORPORATION (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 7.01. Regulation FD Disclosure. The attached presentation materials contain updated information that the members of Trustmark Corporation (the “Company”) management will use during visits with investors, analysts, and other interested parties to assist their understanding of the Company from time to time throughout the fourth quarter of 2025. As provided in General Instruction B.2 to Form 8-K, the information furnished in Item 7.01 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 (the “Exchange Act”), 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, or the Exchange Act, except as shall be expressly set forth by specific reference in such filing.   Item 9.01. Financial Statements and Exhibits. (d) Exhibits   Exhibit Number    Description of Exhibits 99.1    Investor slide presentation, dated November 12, 2025 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:   November 12, 2025