X0609 4 2026-04-23 1 0001845337 Day One Biopharmaceuticals, Inc. DAWN 0001655962 York Charles N II false 1800 SIERRA POINT PARKWAY, SUITE 200 BRISBANE CA 94005 false true false false COO and CFO 0 Common Stock 2026-04-23 4 D 0 312025 D 0 D Stock Option (right to buy Common Stock) 8.99 2026-04-23 4 D 0 497667 D 2031-05-25 Common Stock 497667 0 D Stock Option (right to buy Common Stock) 8.99 2026-04-23 4 D 0 151000 D 2032-01-17 Common Stock 151000 0 D Stock Option (right to buy Common Stock) 8.99 2026-04-23 4 D 0 116000 D 2033-01-16 Common Stock 116000 0 D Stock Option (right to buy Common Stock) 8.99 2026-04-23 4 D 0 162000 D 2034-01-04 Common Stock 162000 0 D Stock Option (right to buy Common Stock) 8.99 2026-04-23 4 D 0 162000 D 2035-01-14 Common Stock 162000 0 D Stock Option (right to buy Common Stock) 11.16 2026-04-23 4 D 0 188000 D 2036-01-29 Common Stock 188000 0 D Restricted Stock Unit (RSU) 2026-04-23 4 D 0 6750 D Common Stock 6750 0 D Restricted Stock Unit (RSU) 2026-04-23 4 D 0 46375 D Common Stock 46375 0 D Restricted Stock Unit (RSU) 2026-04-23 4 D 0 72875 D Common Stock 72875 0 D Restricted Stock Unit (RSU) 2026-04-23 4 D 0 118125 D Common Stock 118125 0 D On March 6, 2026, Servier Pharmaceuticals LLC, a Delaware limited liability company ("Parent"), Servier Detroit Inc., a Delaware corporation and a wholly owned subsidiary of Parent ("Merger Sub"), Day One Biopharmaceuticals, Inc., a Delaware corporation (the "Company"), and Servier S.A.S., a French societe par actions simplifiee, solely as a guarantor, entered into an Agreement and Plan of Merger (the "Merger Agreement"). Pursuant to the Merger Agreement, the Merger Sub merged with and into the Company (such merger and the other transactions contemplated by the Merger Agreement, the "Merger") with the Company surviving the Merger as a wholly owned subsidiary of the Parent. Upon the closing of the Merger on April 23, 2026, each issued and outstanding share of the Company's Common Stock, par value $0.0001 per share, was either (x) purchased for $21.50 per share (the "Offer Price"), net to the seller in cash, without interest, and subject to applicable withholding taxes, on the terms and conditions set forth in the Merger Agreement, or (y) automatically converted into the right to receive the Offer Price (the "Merger Consideration"), net to the seller in cash, without interest, and subject to applicable withholding taxes, on the terms and conditions set forth in the Merger Agreement. The options are fully vested. Immediately prior to the effective time of the Merger, all outstanding unvested stock options and unvested restricted stock units became fully vested. At the effective time of the Merger, each stock option and restricted stock unit was canceled and converted into the right to receive an amount in cash equal to the Merger Consideration (or, in the case of stock options, the difference between the Merger Consideration and the applicable per share exercise price), less any applicable withholding taxes. The option vests as to 2.0833% of the total shares monthly, with 100% of the total shares vested on January 18, 2026, subject to the Reporting Person's provision of service to the Issuer on each vesting date. The option vests as to 1/48th of the total shares monthly, commencing February 17, 2023, subject to the Reporting Person's provision of service to the Issuer on each vesting date. The option vests as to 1/48th of the total shares monthly, commencing February 5, 2024, subject to the Reporting Person's provision of service to the Issuer on each vesting date. The option vests as to 1/48th of the total shares monthly, commencing February 15, 2025, subject to the Reporting Person's provision of service to the Issuer on each vesting date. The option vests as to 1/48th of the total shares monthly, commencing February 28, 2026, subject to the Reporting Person's provision of service to the Issuer on each vesting date. Each restricted stock unit ("RSU") represents a contingent right to receive one share of the Issuer's Common Stock upon settlement for no consideration. The RSUs will vest as to 1/16th of the total award in quarterly installments on February 15, May 15, August 15 and November 15, subject to the Reporting Person's provision of service to the Issuer on each vesting date. RSUs do not expire; they either vest or are canceled prior to the RSU Vesting Date. The RSUs will vest as to 1/16th of the total award in quarterly installments on February 15, May 15, August 15 and November 15, subject to the Reporting Person's provision of service to the Issuer on each vesting date. /s/ Charles N. York II 2026-04-23