Sec Form 4 Filing - Allen Andrew R @ Gritstone bio, Inc. - 2024-02-01

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

OMB APPROVAL OMB Number: 3235-0287 Expires: November 30, 2011 Estimated average burden hours per response... 0.5

1. Name and Address of Reporting Person Allen Andrew R 2. Issuer Name and Ticker or Trading Symbol Gritstone bio, Inc. [ GRTS] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) PRESIDENT AND CEO (Last) (First) (Middle) C/O GRITSTONE BIO, INC., 5959 HORTON STREET, SUITE 300 3. Date of Earliest Transaction (MM/DD/YY) 02/01/2024 (Street) EMERYVILLE, CA94608 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 02/01/2024 A 105,000 ( 1 ) A $ 0 899,345 ( 2 ) D Common Stock 1,449,275 I See footnote ( 3 )

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) $ 2.46 02/01/2024 A 615,000 ( 4 ) 01/31/2034 Common Stock 615,000 $ 0 615,000 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Allen Andrew R C/O GRITSTONE BIO, INC. 5959 HORTON STREET, SUITE 300 EMERYVILLE, CA94608 X PRESIDENT AND CEO Signatures /s/ Vassiliki Economides, Attorney-in-Fact for Andrew R. Allen 02/05/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents Restricted Stock Units ("RSUs") of which 1/2 vests on the first anniversary of the grant date, with the remainder of grant vesting on the second anniversary of the grant date, subject to the continued service of the Reporting Person on each vesting date. Each RSU represents a contingent right to receive one share of the Issuer's Common Stock. ( 2 )Includes 781,145 RSUs which are subject to vesting. ( 3 )The shares are held in the name of the Reporting Person's revocable trust of which the Reporting Person is a co-trustee. The Reporting person disclaims beneficial ownership of the shares except to the extent of his pecuniary interest therein. ( 4 )The option vests as to 1/24th of the total grant monthly beginning February 1, 2024 until such time as the option is 100% vested, subject to the continued service of the Reporting Person on each vesting date.

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).

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.