MARTEN TRANSPORT LTD 10-Q

Item 5. Other Information. During the three months ended March 31, 2026, none of our directors or “officers” (as defined in Rule 16a-1(f) under the Exchange Act) adopted or terminated a “Rule 10b5-1 trading arrangement” or “non-Rule 10b5-1 trading arrangement,” as each term is defined in Item 408 of Securities and Exchange Commission Regulation S-K. Item 6. Exhibits. Item No. Item Method of Filing 31.1 Certification pursuant to Item 601(b)(31) of Regulation S-K, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002, by Randolph L. Marten, the Registrant’s Chairman of the Board and Chief Executive Officer (Principal Executive Officer) Filed with this Report. 31.2 Certification pursuant to Item 601(b)(31) of Regulation S-K, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002, by James J. Hinnendael, the Registrant’s Executive Vice President and Chief Financial Officer (Principal Financial Officer) Filed with this Report. 32.1 Certification pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 Filed with this Report. 101 The following financial information from Marten Transport, Ltd.’s Quarterly Report on Form 10-Q for the period ended March 31, 2026, filed with the SEC on May 8, 2026, formatted in iXBRL, or Inline eXtensible Business Reporting Language: (i) Consolidated Condensed Balance Sheets, (ii) Consolidated Condensed Statements of Operations, (iii) Consolidated Condensed Statements of Stockholders’ Equity, (iv) Consolidated Condensed Statements of Cash Flows, and (v) Notes to Consolidated Condensed Financial Statements Filed with this Report. 104 The cover page from Marten Transport, Ltd.’s Quarterly Report on Form 10-Q for the period ended March 31, 2026, formatted in iXBRL, included in Exhibit 101 Filed with this Report. 19 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, thereunto duly authorized. MARTEN TRANSPORT, LTD. Dated: May 8, 2026 By: /s/ Randolph L. Marten Randolph L. Marten Chairman of the Board and Chief Executive Officer (Principal Executive Officer) Dated: May 8, 2026 By: /s/ James J. Hinnendael James J. Hinnendael Executive Vice President and Chief Financial Officer (Principal Financial and Accounting Officer) 20