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 Date of Report (Date of earliest event reported) February 27, 2026     SIMMONS FIRST NATIONAL CORPORATION (Exact name of registrant as specified in its charter)       Arkansas   0-6253   71-0407808 (State or other jurisdiction of incorporation)   (Commission File Number)   (I.R.S. Employer Identification No.)   501 Main Street , Pine Bluff , Arkansas   71601 (Address of principal executive offices)   (Zip Code) (870) 541-1000 (Registrant’s telephone number, including area code) Not Applicable (Former name or former address, if changed since last report.)     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 (see General Instruction A.2. below):   ☐ 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, par value $0.01 per share   SFNC   The 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 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers. On February 27, 2026, Simmons First National Corporation (“Corporation”), Simmons Bank (“Bank”), and James M. Brogdon entered into a First Amendment to Executive Change in Control Severance Agreement (“Amendment”). The Amendment amends the Executive Change in Control Severance Agreement dated July 30, 2021, among the Corporation, the Bank, and Mr. Brogdon (“Agreement”) by changing the formula for “termination compensation” under the Agreement from two (2) times Mr. Brogdon’s Base Period Income (as defined in the Agreement) to three (3) times Mr. Brogdon’s Base Period Income. The foregoing description of the Amendment does not purport to be complete and is qualified in its entirety by reference to the complete text of the Amendment, which is attached as Exhibit 10.1 to this Current Report on Form 8-K, and incorporated by reference herein. Item 9.01 Financial Statements and Exhibits.   Exhibit No.    Description 10.1    First Amendment to Executive Change in Control Severance Agreement for James M. Brogdon dated February 27, 2026. 104    Cover Page Interactive Data File (embedded within the Inline XBRL document).   SIGNATURE 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.         SIMMONS FIRST NATIONAL CORPORATION       /s/ C. Daniel Hobbs Date: March 3, 2026       C. Daniel Hobbs, Executive Vice President and Chief Financial Officer