SEC FORM 4

SEC FORM 4SEC Form 4

FORM 4

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
or Section 30(h) of the Investment Company Act of 1940

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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Dubow Adam

(Last)

(First)

(Middle)

1800 SIERRA POINT PARKWAY, SUITE 200

(Street)

BRISBANE

CALIFORNIA

94005

(City)

(State)

(Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Day One Biopharmaceuticals, Inc. [ DAWN ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director	10% Owner
X	Officer (give title below)	Other (specify below)
	Gen Counsel & Secretary

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
04/23/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	04/23/2026		D		72,694	D	⁽¹⁾⁽²⁾	0	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 (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	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 (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (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: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
Stock Option (right to buy Common Stock)	$8.99	04/23/2026		D			309,000	⁽³⁾	10/30/2032	Common Stock	309,000	⁽⁴⁾	0	D
Stock Option (right to buy Common Stock)	$8.99	04/23/2026		D			90,000	⁽⁵⁾	01/16/2033	Common Stock	90,000	⁽⁴⁾	0	D
Stock Option (right to buy Common Stock)	$8.99	04/23/2026		D			90,000	⁽⁶⁾	01/04/2034	Common Stock	90,000	⁽⁴⁾	0	D
Stock Option (right to buy Common Stock)	$8.99	04/23/2026		D			90,000	⁽⁷⁾	01/14/2035	Common Stock	90,000	⁽⁴⁾	0	D
Stock Option (right to buy Common Stock)	$11.16	04/23/2026		D			105,000	⁽⁸⁾	01/29/2036	Common Stock	105,000	⁽⁴⁾	0	D
Restricted Stock Unit (RSU)	⁽⁹⁾	04/23/2026		D			8,889	⁽¹⁰⁾	⁽¹¹⁾	Common Stock	8,889	⁽⁴⁾	0	D
Restricted Stock Unit (RSU)	⁽⁹⁾	04/23/2026		D			5,250	⁽¹²⁾	⁽¹¹⁾	Common Stock	5,250	⁽⁴⁾	0	D
Restricted Stock Unit (RSU)	⁽⁹⁾	04/23/2026		D			25,816	⁽¹²⁾	⁽¹¹⁾	Common Stock	25,816	⁽⁴⁾	0	D
Restricted Stock Unit (RSU)	⁽⁹⁾	04/23/2026		D			40,565	⁽¹²⁾	⁽¹¹⁾	Common Stock	40,565	⁽⁴⁾	0	D
Restricted Stock Unit (RSU)	⁽⁹⁾	04/23/2026		D			65,625	⁽¹²⁾	⁽¹¹⁾	Common Stock	65,625	⁽⁴⁾	0	D

Explanation of Responses:

1. 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.

2. 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.

3. The option vests as to 100% of the total shares on November 6, 2026, subject to the Reporting Person's provision of service to the Issuer on such vesting date.

4. 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.

5. 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.

6. 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.

7. 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.

8. 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.

9. Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of the Issuer's Common Stock upon settlement.

10. The Restricted Stock Units ("RSUs") vest as to 25% of the total award on November 15, 2023, and 1/12th of the remaining amount vests 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.

11. RSUs do not expire; they either vest or are canceled prior to the vesting date.

12. 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, as Attorney-in-Fact	04/23/2026
	** Signature of Reporting Person	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.
* Form 4: SEC 1474 (03-26)

Gen Counsel & Secretary Dubow Adam returned 72,694 shares to the company, closing all direct ownership in the company (SEC Form 4) to cover taxes