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).

1. Name and Address of Reporting Person* Grant Papanek Julie (Last) (First) (Middle) 395 OYSTER POINT BLVD, SUITE 217 (Street) SOUTH SAN FRANCISCO CA 94080 (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) X Director 10% Owner Officer (give title below) Other (specify below)
	3. Date of Earliest Transaction (Month/Day/Year) 02/01/2021
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) X Form filed by One Reporting Person 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	06/01/2021		C		7,328,497	A	(1)	10,574,366	I	By Canaan XI, L.P.(2)
Common Stock	06/01/2021		C		148,279	A	(3)	10,722,645	I	By Canaan XI, L.P.(2)
Common Stock	06/01/2021		P		13,000	A	$16	10,735,645	I	By Canaan XI, L.P.(2)
Common Stock								465,000	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)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Series B Preferred Stock	(4)	02/01/2021		A		148,279(5)		(4)	(4)	Common Stock(4)	148,279(5)	(4)	148,279(5)	I	By Canaan XI, L.P.(2)
Stock Option (right to buy Common Stock)(6)	$16	05/26/2021		A		63,000		(7)	05/25/2031	Common Stock	63,000(6)	$0.00	63,000	D
Series A Preferred Stock	(1)	06/01/2021		C			7,328,497	(1)	(1)	Common Stock	7,328,497	$0.00	0	I	By Canaan XI, L.P.(2)
Series B Preferred Stock	(3)	06/01/2021		C			148,279	(3)	(3)	Common Stock	148,279	$0.00	0	I	By Canaan XI, L.P.(2)

Explanation of Responses:

1. The shares of the Issuer's Series A Preferred Stock automatically converted on a one-for-one basis into shares of the Issuer's Common Stock on May 26, 2021 in connection with the closing of the Issuer's sale of its Common Stock in its firm commitment initial public offering (the "IPO") pursuant to a registration statement on Form S-1 (File No. 333-255754) under the Securities Act of 1933, as amended (the "Registration Statement"), and had no expiration date.

2. Represents securities held by Canaan XI, L.P. ("Canaan LP"). The Reporting Person, as a non-managing member of Canaan LP's general partner, Canaan Partners XI LLC, disclaims beneficial ownership of such securities except to the extent of her pecuniary interest therein, if any.

3. The shares of the Issuer's Series B Preferred Stock automatically converted on a one-for-one basis into shares of the Issuer's Common Stock on May 26, 2021 in connection with the closing of the Issuer's sale of its Common Stock in its IPO pursuant to the Registration Statement, and had no expiration date.

4. The Reporting Person is reporting the purchase of these securities pursuant to Rule 16a-2(a) of the Securities Exchange Act of 1934, as amended (the "Exchange Act"). Each share of Series B Preferred Stock automatically converted into one share of Common Stock at the close of the Issuer's IPO and has no expiration date.

5. The number of securities reported reflects the 1 to 2.325 stock split of the Issuer's Common Stock and convertible preferred stock that was effected on May 23, 2021.

6. The Reporting Person is reporting the acquisition of these securities pursuant to Rule 16a-2(a) of the Exchange Act.

7. The option vests as to 1/36th of the total shares on each monthly anniversary, beginning on June 23, 2021, subject to the Reporting Person's provision of service to the Issuer on each vesting date.

Remarks:

	/s/ Julie Papanek Grant	06/03/2021
	** Signature of Reporting Person	Date
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* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
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