EXAGEN INC. 10-Q

Item 5. Other Information Rule 10b5-1 trading arrangements During the three months ended September 30, 2025, none of our directors or officers adopted , modified or terminated a "Rule 10b5-1 trading arrangement" or "non-Rule 10b5-1 trading arrangement," as each term is defined in Item 408 of Regulation S-K. 37 Item 6. Exhibits Incorporated by Reference Exhibit Number Exhibit Description Form File No. Exhibit Exhibit Filing Date Filed/Furnished Herewith 3.1 Amended and Restated Certificate of Incorporation. 8-K 001-39049 3.1 9/23/2019 3.2 Amended and Restated Bylaws. 8-K 001-39049 3.1 3/22/2021 3.3 Amendment to Amended and Restated Bylaws, dated January 19, 2023 . 8-K 001-39049 3.1 1/23/2023 4.1 Specimen stock certificate evidencing the shares of common stock. S-1/A 333-233446 4.1 9/9/2019 4.2 Form of Common Stock Purchase Warrant issued to investors by the Company in connection with private placement financings. S-1/A 333-233446 4.4 9/9/2019 4.3 Form of Common Stock Purchase Warrant to purchase common stock issued to investors by the Company in 2016. S-1/A 333-233446 4.8 9/9/2019 4.4 Form of Exchange Warrant 10-Q 001-39049 4.5 8/9/2021 4.5 Warrant Certificate, dated April 25, 2025, issued by the Company to Perceptive Credit Holdings IV, LP. 8-K 001-39049 4.1 4/28/2025 10.1 Amended & Restated Non-Employee Director Compensation Program 8-K 001-39049 10.1 7/17/2025 31.1 Certificate of Principal Executive Officer, pursuant to Rule 13a-14(a)/15d-14(a), as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. X 31.2 Certificate of Principal Financial Officer, pursuant to Rule 13a-14(a)/15d-14(a), as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. X 32.1* Certifications Pursuant to U.S.C. Section 1350, As Adopted Pursuant to Section 906 of the Public Company Accounting Reform and Investor Protection Act of 2002. X 101.INS Inline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document. X 101.SCH Inline XBRL Taxonomy Extension Schema Document. X 101.CAL Inline XBRL Taxonomy Extension Calculation Linkbase Document. X 101.DEF Inline XBRL Taxonomy Extension Definition Linkbase Document. X 101.LAB Inline XBRL Taxonomy Extension Labels Linkbase Document. X 101.PRE Inline XBRL Taxonomy Extension Presentation Linkbase Document. X 104 The cover page from the Company's Quarterly Report on Form 10-Q for the quarter ended September 30, 2025, has been formatted in Inline XBRL. X * Furnished herewith. This certification is deemed not filed for purpose of section 18 of the Exchange Act or otherwise subject to the liability of that section, nor shall it be deemed incorporated by reference into any filing under the Securities Act or the Exchange Act. ^ Certain schedules to this exhibit have been omitted pursuant to Item 601(a)(5) of Regulation S-K. Copies of the omitted schedules will be furnished to the SEC upon request. 38 Signatures Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. EXAGEN INC. Date: November 4, 2025 by: /s/ John Aballi John Aballi President and Chief Executive Officer (Principal Executive Officer) Date: November 4, 2025 by: /s/ Jeffrey G. Black Jeffrey G. Black Chief Financial Officer (Principal Financial and Accounting Officer) 39