EXAGEN INC.

Rule 10b5-1 trading arrangements

During the three months ended December 31, 2025, none of our directors or officers adopted orterminated 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.

Insider Trading Policy

We maintain an Insider Trading Policy that, among other things, prohibits all officers, directors, and other employees with access to sensitive Company information from engaging in “hedging” transactions with respect to our shares. This includes short sales, hedging of share ownership positions, and transactions involving derivative securities relating to our shares. The Insider Trading Policy also generally prohibits borrowing or other arrangements involving the non-recourse pledge of our shares. This policy is included as Exhibit 19 to this Annual Report.

Credit Agreement Amendment

On March 6, 2026, the Company and Perceptive entered into a first amendment to the Credit Agreement. This amendment, among other changes, terminated the Tranche C Term Loan Commitment (as defined therein), extended the availability of the $10.0 million Tranche B Term Loan (as defined therein) to September 30, 2026, increased the trailing twelve month net revenue milestone applicable to the Tranche B Borrowing Date (as defined therein), and revised certain financial covenant thresholds. The first amendment did not change the stated maturity of the existing term loans and reaffirmed the existing liens and guarantees securing the credit facility. As a result of this amendment, the number of shares of common stock subject to future vesting pursuant to the Warrant Certificate has been reduced from up to 750,000 shares of common stock to up to 600,000 shares of common stock that will vest and become exercisable if and when the remaining additional debt tranches (Tranche B and/or Tranche D) are drawn by the Company.

The descriptions of the first amendment and Credit Agreement are qualified by their entirety by the full text of the Credit Agreement and amendment, attached as Exhibits 10.41 and 10.42, respectively, to this Annual Report.