Statement of Changes in Beneficial Ownership (4)

FORM 4 ☐ Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response... 0.5
	Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

1. Name and Address of Reporting Person * AI Day1 LLC	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)
(Last)          (First)          (Middle) C/O ACCESS INDUSTRIES, INC., 40 WEST 57TH STREET, 28TH FLOOR	3. Date of Earliest Transaction (MM/DD/YYYY) 6/9/2023
(Street) NEW YORK, NY 10019	4. If Amendment, Date Original Filed (MM/DD/YYYY)	6. Individual or Joint/Group Filing (Check Applicable Line) ___ Form filed by One Reporting Person _ X _ Form filed by More than One Reporting Person
(City)        (State)        (Zip)	Rule 10b5-1(c) Transaction Indication ☐ Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security (Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	3. Trans. 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)
			Code	V	Amount	(A) or (D)	Price
Common Stock	6/9/2023		P		769230	A	$13.00	11453868	D (1)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	4. Trans. 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		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 of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

(1)

The securities reported are held directly by AI Day1 LLC and may be deemed to be beneficially owned by Access Industries Holdings LLC ("AIH"), Access Industries Management, LLC ("AIM") and Len Blavatnik because AIH indirectly controls all of the outstanding voting interests in AI Day1 LLC, AIM controls AIH and Mr. Blavatnik controls AIM and controls a majority of the outstanding voting interests in AIH. AIH, AIM and Mr. Blavatnik each 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.

Reporting Owners
Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
AI Day1 LLC C/O ACCESS INDUSTRIES, INC. 40 WEST 57TH STREET, 28TH FLOOR NEW YORK, NY 10019		X
Access Industries Holdings LLC C/O ACCESS INDUSTRIES, INC. 40 WEST 57TH STREET, 28TH FL NEW YORK, NY 10019				Affiliate of 10% Owner
ACCESS INDUSTRIES MANAGEMENT, LLC C/O ACCESS INDUSTRIES, INC. 40 WEST 57TH STREET, 28TH FLOOR NEW YORK, NY 10019				Affiliate of 10% Owner
Blavatnik Len C/O ACCESS INDUSTRIES, INC. 40 WEST 57TH STREET, 28TH FL NEW YORK, NY 10019				Affiliate of 10% Owner

Signatures
/s/ Alejandro Moreno for AI Day1 LLC		6/12/2023
**Signature of Reporting Person		Date
/s/ Alejandro Moreno for Access Industries Holdings LLC		6/12/2023
**Signature of Reporting Person		Date
/s/ Alejandro Moreno for Access Industries Management, LLC		6/12/2023
**Signature of Reporting Person		Date
/s/ Alejandro Moreno as Attorney-in-Fact for Mr. Blavatnik		6/12/2023
**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 control number.