Sec Form 4 Filing - Zack Debra @ EXAGEN INC. - 2021-02-23

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Zack Debra 2. Issuer Name and Ticker or Trading Symbol EXAGEN INC. [ XGN] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Chief Medical Officer (Last) (First) (Middle) C/O EXAGEN INC., 1261 LIBERTY WAY 3. Date of Earliest Transaction (MM/DD/YY) 02/23/2021 (Street) VISTA, CA92081 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock ( 1 ) 02/23/2021 A 37,500 A $ 0 37,500 ( 2 ) D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Stock Option(right to buy) $ 18.2 02/23/2021 A 12,500 ( 3 ) 02/22/2031 Common Stock 12,500 $ 0 12,500 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Zack Debra C/O EXAGEN INC. 1261 LIBERTY WAY VISTA, CA92081 Chief Medical Officer Signatures /s/ Kamal Adawi, as attorney-in-fact 02/25/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents restricted stock units. Each restricted stock unit represents a contingent right to receive one share of the Issuer's common stock. The restricted stock units will vest with respect to 25% of the restricted stock units on each of the first, second, third and fourth anniversaries of March 1, 2020, subject to the Reporting Person's continued service through the applicable vesting date. In addition, the award may become fully vested upon a qualifying termination of employment in connection with a change in control. ( 2 )Represents 37,500 shares of restricted stock units. ( 3 )The option is exercisable as it vests. 25% of the shares subject to the option vest on February 23, 2022, and 1/48th of the total number of shares subject to the option vest monthly thereafter, subject to the Reporting Person's continued service to the Issuer through each such vesting date. In addition, the stock option may become fully vested upon a qualifying termination of employment in connection with a change in control.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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