TRUSTMARK CORP

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

for the fiscal year ended December 31,2025

or

Commission file number 000-3683

TRUSTMARK CORP ORATION

(Exact name of Registrant as specified in its charter)

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes ☑ No ☐

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes ☐No ☑

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☑ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☑ No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See definition of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

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. ☐

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report.☑

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements.☐

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant’s executive officers during the relevant recovery period pursuant to §240.10D-1(b). ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act.) Yes ☐ No☑

Based on the closing sales price at June 30, 2025, the last business day of the registrant’s most recently completed second fiscal quarter, the aggregate market value of the shares of common stock held by nonaffiliates of the registrant was approximately $961.6 million.

As of January 30, 2026, there were issued and outstanding 58,849,788 shares of the registrant’s Common Stock.

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the Proxy Statement for Trustmark’s 2026 Annual Meeting of Shareholders to be held April 28, 2026 are incorporated by reference into Part III of the Form 10-K report.

TRUSTMARK CORPORATION

ANNUAL REPORT ON FORM 10-K

TABLE OF CONTENTS

Forward-Looking Statements

Certain statements contained in this Annual Report on Form 10-K constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. You can identify forward-looking statements by words such as “may,” “hope,” “will,” “should,” “expect,” “plan,” “anticipate,” “intend,” “believe,” “estimate,” “predict,” “project,” “potential,” “seek,” “continue,” “could,” “would,” “future” or the negative of those terms or other words of similar meaning. You should read statements that contain these words carefully because they discuss our future expectations or state other “forward-looking” information. These forward-looking statements include, but are not limited to, statements relating to anticipated future operating and financial performance measures, including net interest margin, credit quality, business initiatives, growth opportunities and growth rates, among other things, and encompass any estimate, prediction, expectation, projection, opinion, anticipation, outlook or statement of belief included therein as well as the management assumptions underlying these forward-looking statements. You should be aware that the occurrence of the events described under the caption Item 1A. Risk Factors in this report could have an adverse effect on our business, results of operations and financial condition. Should one or more of these risks materialize, or should any such underlying assumptions prove to be significantly different, actual results may vary significantly from those anticipated, estimated, projected or expected.

Risks that could cause actual results to differ materially from current expectations of Management include, but are not limited to, actions by the Board of Governors of the Federal Reserve System (FRB) that impact the level of market interest rates, local, state, national and international economic and market conditions, conditions in the housing and real estate markets in the regions in which Trustmark operates, conditions and changes, including volatility, in the credit and financial markets, changes in the level of nonperforming assets and charge-offs, an increase in unemployment levels, a slowdown in economic growth, changes in our ability to measure the fair value of assets in our portfolio, changes in the level and/or volatility of market interest rates, the impacts related to or resulting from bank failures and other economic and industry volatility, including potential increased regulatory requirements, the demand for the products and services we offer, potential unexpected adverse outcomes in pending litigation matters, our ability to attract and retain noninterest-bearing deposits and other low-cost funds, competition in loan and deposit pricing, as well as the entry of new competitors into our markets through de novo expansion and acquisitions, changes in accounting standards and practices, including changes in the interpretation of existing standards, that affect our consolidated financial statements, changes in consumer spending, borrowings and savings habits, technological changes, changes in the financial performance or condition of our borrowers, greater than expected costs or difficulties related to the integration of acquisitions or new products and lines of business, cyber-attacks and other breaches which could affect our information system security, natural disasters, environmental disasters, pandemics or other health crises, acts of war or terrorism, potential market or regulatory effects of the current United States presidential administration’s policies, changes to the credit rating of U.S. Government securities and other risks described in our filings with the Securities and Exchange Commission (SEC).

Although we believe that the expectations reflected in such forward-looking statements are reasonable, we can give no assurance that such expectations will prove to be correct. Except as required by law, we undertake no obligation to update or revise any of this information, whether as the result of new information, future events or developments or otherwise.