Management Change/Compensation - Form 8-K

Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

On April 24, 2024, Steve Krognes, a member of the Board of Directors (the "Board") of Gritstone bio, Inc. (the "Company"), delivered notice to the Chair of the Board of his decision not to stand for re-electionat the Company's upcoming annual meeting of stockholders, to be held on June 17, 2024. Mr. Krognes's decision not to stand for re-electionis not due to any disagreement with the Company or the Board on any matters relating to the Company's operations, policies, or practices.

On April 26, 2024, upon the recommendation of the Nominating and Corporate Governance Committee of the Board, the Board appointed Stephen W. Webster as a director of the Company, effective immediately. Mr. Webster will serve as a Class I director with a term expiring at the Company's 2025 annual meeting of stockholders. Mr. Webster has been appointed as a member of the Audit Committee and Compensation Committee of the Board, effective as of April 26, 2024. Mr. Webster will assume the position of Chair of the Audit Committee of the Board effective as of the conclusion of Mr. Krognes's term at the 2024 annual meeting of stockholders.

As provided in the Amended and Restated Gritstone bio, Inc. (f/k/a Gritstone Oncology, Inc.) Non-EmployeeDirector Compensation Program (the "Director Compensation Program"), a copy of which was filed as Exhibit 10.10 to the Company's Annual Report on Form 10-Kfor the year ended December 31, 2023, filed with the Securities and Exchange Commission on March 5, 2024, Mr. Webster will receive an annual cash retainer of $40,000 per year for his service as a Class I director and additional annual retainers for committee service. Under the Director Compensation Program, upon the effectiveness of his appointment, Mr. Webster was automatically granted an option under the Company's 2018 Incentive Award Plan (the "Incentive Award Plan") to purchase 103,600 shares of the Company's common stock (the "Initial Option"). The Initial Option vests in substantially equal monthly installments for three years from the date of grant, subject to continued service through each applicable vesting date. The exercise price per share of the Initial Option is equal to the Fair Market Value (as such term is defined in the Incentive Award Plan) of a share of the Company's common stock determined pursuant to the Incentive Award Plan. Mr. Webster is also expected to enter into the Company's standard indemnification agreement.

There are no arrangements or understandings between Mr. Webster and any other persons pursuant to which he was selected as a director of the Company. Mr. Webster is not a party to any transaction required to be disclosed pursuant to Item 404(a) of Regulation S-K.