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

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

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^*

AI Day1 LLC

(Last)

(First)

(Middle)

C/O ACCESS INDUSTRIES, INC.

40 WEST 57TH STREET, 28TH FLOOR

(Street)

NEW YORK

10019

(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	X	10% Owner
Officer (give title below)		Other (specify below)

2a. Foreign Trading Symbol

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

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

	Form filed by One Reporting Person
X	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		U⁽¹⁾		12,929,322⁽¹⁾	D	$21.5	0	D⁽²⁾

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)
Pre-Funded Warrant (right to buy)	$0.0001	04/23/2026		D⁽¹⁾			827,586⁽¹⁾	⁽³⁾	⁽³⁾	Common Stock	827,586	$21.4999	0	D⁽²⁾

1. Name and Address of Reporting Person^*

AI Day1 LLC

(Last)

(First)

(Middle)

C/O ACCESS INDUSTRIES, INC.

40 WEST 57TH STREET, 28TH FLOOR

(Street)

NEW YORK

10019

(City)

(State)

(Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

Director	X	10% Owner
Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

Access Industries Holdings LLC

(Last)

(First)

(Middle)

C/O ACCESS INDUSTRIES, INC.

40 WEST 57TH STREET, 28TH FLOOR

(Street)

NEW YORK

10019

(City)

(State)

(Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

Director	X	10% Owner
Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

ACCESS INDUSTRIES MANAGEMENT, LLC

(Last)

(First)

(Middle)

C/O ACCESS INDUSTRIES, INC.

40 WEST 57TH STREET, 28TH FLOOR

(Street)

NEW YORK

10019

(City)

(State)

(Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

Director	X	10% Owner
Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

Blavatnik Len

(Last)

(First)

(Middle)

C/O ACCESS INDUSTRIES, INC.

40 WEST 57TH STREET, 28TH FLOOR

(Street)

NEW YORK

10019

(City)

(State)

(Zip)

UNITED STATES

(Country)

Relationship of Reporting Person(s) to Issuer

Director	X	10% Owner
Officer (give title below)		Other (specify below)

Explanation of Responses:

1. On April 9, 2026, AI Day1 tendered all of its shares of Common Stock pursuant to the tender offer by Servier Detroit Inc. ("Purchaser") to purchase all of the issued and outstanding shares of Common Stock for $21.50 per share in cash, upon the terms and subject to the conditions described in the Offer to Purchase and related Letter of Transmittal filed with the SEC on Schedule TO on March 26, 2026. Such shares were accepted by the Purchaser on April 23, 2026. On April 23, 2026, in connection with the consummation of the merger, each pre-funded warrant held by AI Day1 to purchase Common Stock was converted into the right to receive $21.4999 per warrant in cash.

2. The securities reported are held directly by AI Day1 LLC ("AI Day1") and may be deemed to be beneficially owned by Access Industries Holdings LLC ("AIH"), Access Industries Management, LLC ("AIM") and Len Blavatnik because (i) Mr. Blavatnik controls AIM and AIH, (ii) AIM controls AIH, and (iii) AIH owns all of the voting units of AI Day1. Each of AIH, AIM and Mr. Blavatnik, and each of their affiliated entities and the officers, partners, members and managers thereof, disclaims beneficial ownership of these securities, except to the extent of its or his pecuniary interest therein, and this form shall not be construed as an admission that any such reporting person is the beneficial owner of any of the securities reported on this form.

3. Each pre-funded warrant is exercisable at any time after the date of issuance and the pre-funded warrants do not expire. The pre-funded warrants are not exercisable to the extent that the aggregate number of shares of Common Stock beneficially owned by AI Day1 LLC, including together with its direct or indirect affiliates, any person acting or who could be deemed to be acting as a group together with the holder, and any other persons whose beneficial ownership of the Common Stock would or could be aggregated with the holder's for the purposes of Section 13(d) or Section 16 of the Exchange Act of 1934, as amended, immediately following such exercise would exceed 9.99%; provided, however, that AI Day1 LLC may increase or decrease the beneficial ownership limitation by giving 61 days' notice to the Issuer, but not to exceed any percentage in excess of 19.99%.

	/s/ Alejandro Moreno for AI Day1 LLC	04/27/2026
	/s/ Alejandro Moreno for Access Industries Holdings LLC	04/27/2026
	/s/ Alejandro Moreno for Access Industries Management, LLC	04/27/2026
	/s/ Alejandro Moreno, as Attorney-in-Fact for Mr. Blavatnik	04/27/2026
	** 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)

SEC Form 4 filed by Large owner Ai Day1 Llc