SEC 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 NY 10019 (City) (State) (Zip)	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)
	3. Date of Earliest Transaction (Month/Day/Year) 10/18/2023
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) Form filed by One Reporting Person X Form filed by More than One Reporting Person

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)
			Code	V	Amount	(A) or (D)	Price
Common Stock	10/18/2023		P		979,667	A	$10.2076(1)	12,433,535	D(2)
Common Stock	10/19/2023		P		384,400	A	$10.0608(3)	12,817,935	D(2)
Common Stock	10/20/2023		P		111,387	A	$9.9734(4)	12,929,322	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)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

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 NY 10019 (City) (State) (Zip) 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 FL (Street) NEW YORK NY 10019 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director 10% Owner Officer (give title below) X Other (specify below) Affiliate of 10% Owner

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 NY 10019 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director 10% Owner Officer (give title below) X Other (specify below) Affiliate of 10% Owner

1. Name and Address of Reporting Person* Blavatnik Len (Last) (First) (Middle) C/O ACCESS INDUSTRIES, INC. 40 WEST 57TH STREET, 28TH FL (Street) NEW YORK NY 10019 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director 10% Owner Officer (give title below) X Other (specify below) Affiliate of 10% Owner

Explanation of Responses:

1. The price reported in Column 4 is a weighted average purchase price of the shares of common stock. The shares of common stock were purchased in multiple transactions ranging from $10.07 to $10.29 inclusive. The reporting persons undertake to provide to Day One Biopharmaceuticals, Inc., any security holder of Day One Biopharmaceuticals, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares of common stock purchased at each separate price within the ranges set forth in this footnote to this Form 4.

2. 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.

3. The price reported in Column 4 is a weighted average purchase price of the shares of common stock. The shares of common stock were purchased in multiple transactions ranging from $9.88 to $10.20 inclusive. The reporting persons undertake to provide to Day One Biopharmaceuticals, Inc., any security holder of Day One Biopharmaceuticals, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares of common stock purchased at each separate price within the ranges set forth in this footnote to this Form 4.

4. The price reported in Column 4 is a weighted average purchase price of the shares of common stock. The shares of common stock were purchased in multiple transactions ranging from $9.83 to $10.13 inclusive. The reporting persons undertake to provide to Day One Biopharmaceuticals, Inc., any security holder of Day One Biopharmaceuticals, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares of common stock purchased at each separate price within the ranges set forth in this footnote to this Form 4.

Remarks:

	/s/ Alejandro Moreno for AI Day1 LLC	10/20/2023
	/s/ Alejandro Moreno for Access Industries Holdings LLC	10/20/2023
	/s/ Alejandro Moreno for Access Industries Management, LLC	10/20/2023
	/s/ Alejandro Moreno as Attorney-in-Fact for Mr. Blavatnik	10/20/2023
	** Signature of Reporting Person	Date
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