Acquisition / Disposition · Reg FD Disclosure

Securities and Exchange Commission (the “SEC”) on December 22, 2021 and amended on January 18, 2022 (the “Registration Statement”). At the effective time of the Merger, pursuant to the terms of the Merger Agreement, each share of common stock, no par value, of Spirit was converted into 1.0016722 shares of Class A Common Stock, $0.01 par value per share, of the Company (the “Company common stock”), with cash paid in lieu of fractional shares of Company common stock and to cash out Spirit stock options and warrants that were outstanding immediately prior to the effective time of the Merger. The foregoing summary of the Merger Agreement and the Merger is not complete and is qualified in its entirety by reference to the complete text of the Merger Agreement, which is incorporated by reference as Exhibit 2.1 hereto and is incorporated herein by reference. Item 7.01 Regulation FD Disclosure. On April 11, 2022, the Company issued a press release announcing the consummation of the Merger. A copy of the press release is attached hereto as Exhibit 99.1 and is incorporated herein by reference. The information provided pursuant to this Item 7.01 (including Exhibit 99.1) is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934 (the “Exchange Act”) or otherwise subject to the liabilities under that Section and shall not be deemed to be incorporated by reference into any filing of the Company under the Securities Act of 1933 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 2.1   Agreement and Plan of Merger, dated as of November 18, 2021, by and between Simmons First National Corporation and Spirit of Texas Bancshares, Inc. (incorporated herein by reference to the Current Report on Form 8-K filed by Simmons First National Corporation on November 19, 2021)* Exhibit 99.1   Press Release issued by Simmons First National Corporation on April 11, 2022. Exhibit 104   Cover Page Interactive Data File (embedded within the Inline XBRL document).   * Previously filed. Schedules have been omitted pursuant to Item 601(a)(5) of Regulation S-K. A copy of any omitted schedule will be furnished supplementally to the SEC upon request; provided, however, that the parties may request confidential treatment pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended, for any document so furnished.     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       Date: April 11, 2022 By:   /s/ James M. Brogdon     James M. Brogdon     Executive Vice President, Chief Financial Officer and Treasurer