EXELIXIS, INC.

As reported by the Company in its Current Report on Form 8-K dated August 29, 2025, effective as of the same date, Amy C. Peterson, M.D., concluded her service as Executive Vice President, Product Development and Medical Affairs, and Chief Medical Officer of the Company.

In connection with her departure from the Company, the Company and Dr. Peterson entered into a Separation Agreement (the “Separation Agreement”) on November 3, 2025. Pursuant to the Separation Agreement, Dr. Peterson and her designated recipient will receive: (i) the severance payments and benefits that she is entitled to under the Company’s Change in Control and Severance Benefit Plan (“Plan”); and (ii) an amount in consideration of any unvested stock options and restricted stock units forfeited pursuant to the Plan, in the gross amount of $1,000,000, subject to the terms and conditions set forth in the Separation Agreement, including execution and non-revocation of the Release of Claims attached thereto.

The foregoing description of the Separation Agreement does not purport to be complete and is qualified in its entirety by reference to the text of the Separation Agreement, which is expected to be filed as an exhibit to the Company’s Form 10-K for the fiscal year ending on Friday, January 2, 2026.

During the three months ended September 30, 2025, no directors or Section 16 officers of the Company adopted, modified orterminated any “Rule 10b5-1 trading arrangement” or “non-Rule 10b5-1 trading arrangement,” as each term is defined in Item 408 of Regulation S-K.