Sec Form 3 Filing - Ruiz Roger Richard @ Atreca, Inc. - 2023-09-17

FORM 3 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 Ruiz Roger Richard 2. Issuer Name and Ticker or Trading Symbol Atreca, Inc. [ BCEL] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) VP of Finance (Last) (First) (Middle) C/O ATRECA, INC., 835 INDUSTRIAL ROAD, SUITE 400 3. Date of Earliest Transaction (MM/DD/YY) 09/17/2023 (Street) SAN CARLOS, CA94070 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 Class A Common Stock 34,980 ( 1 ) 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 Employee stock option (right to buy) $ 3.18 ( 2 ) 12/22/2031 Class A Common Stock 25,000 D Employee stock option (right to buy) $ 1.845 ( 4 ) ( 3 ) 01/26/2031 Class A Common Stock 28,250 D Employee stock option (right to buy) $ 1.49 ( 5 ) 02/08/2033 Class A Common Stock 50,000 D Employee stock option (right to buy) $ 1.845 ( 4 ) ( 6 ) 10/29/2028 Class A Common Stock 41,666 D Employee stock option (right to buy) $ 1.845 ( 4 ) ( 6 ) 01/30/2029 Class A Common Stock 8,333 D Employee stock option (right to buy) $ 1.845 ( 4 ) ( 7 ) 02/25/2030 Class A Common Stock 27,000 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Ruiz Roger Richard C/O ATRECA, INC. 835 INDUSTRIAL ROAD, SUITE 400 SAN CARLOS, CA94070 VP of Finance Signatures /s/ Roger Richard Ruiz 09/27/2023 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Consists of 26,647 shares of Class A Common Stock and 8,333 restricted stock units pertaining to a restricted stock unit award granted on February 9, 2023, vesting in three equal annual installments beginning on August 1, 2023, subject to the Reporting Person providing continuous service to the Issuer as of each such date. Each restricted stock unit represents a right to receive one share of Class A Common Stock upon vesting. ( 2 )1/48 of the Option vests in equal monthly installments as measured from December 1, 2021, subject to the Reporting Person providing continuous service to the Issuer as of each such date. If applicable, vesting accelerates as provided in,and subject to the terms and conditions of, that certain Executive Employment Agreement between the Issuer and the Reporting Person, as may be amended from time to time. ( 3 )1/48 of the Option vests in equal monthly installments as measured from January 1, 2021, subject to the Reporting Person providing continuous service to the Issuer as of each such date. If applicable, vesting accelerates as provided in, and subject to the terms and conditions of, that certain Executive Employment Agreement between the Issuer and the Reporting Person, as may be amended from time to time. ( 4 )The Board of Directors of the Issuer approved a repricing of this Option, effective June 13, 2022. ( 5 )1/48 of the Option vests in equal monthly installments as measured from January 1, 2023, subject to the Reporting Person providing continuous service to the Issuer as of each such date. If applicable, vesting accelerates as provided in,and subject to the terms and conditions of, that certain Executive Employment Agreement between the Issuer and the Reporting Person, as may be amended from time to time. ( 6 )Fully vested. ( 7 )1/48 of the Option vests in equal monthly installments as measured from January 1, 2020, subject to the Reporting Person providing continuous service to the Issuer as of each such date. If applicable, vesting accelerates as provided in, and subject to the terms and conditions of, that certain Executive Employment Agreement between the Issuer and the Reporting Person, as may be amended from time to time.

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).

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