Atlas Venture Opportunity Fund I Form 3 Initial statement of insider ownership

SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

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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1. Name and Address of Reporting Person^*

Atlas Venture Fund XI, L.P.

(Last) (First) (Middle)

300 TECHNOLOGY SQUARE, 8TH FLOOR

(Street)

CAMBRIDGE MA 02139

(City) (State) (Zip)

2. Date of Event Requiring Statement (Month/Day/Year)
05/26/2021

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

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

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

5. 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 Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Series A Preferred Stock	(1)	(1)	Common Stock	7,761,380	(1)	D(2)
Series B Preferred Stock	(3)	(3)	Common Stock	741,396	(3)	D(4)

1. Name and Address of Reporting Person^*

Atlas Venture Fund XI, L.P.

(Last) (First) (Middle)

300 TECHNOLOGY SQUARE, 8TH FLOOR

(Street)

CAMBRIDGE MA 02139

(City) (State) (Zip)

1. Name and Address of Reporting Person^*

Atlas Venture Opportunity Fund I, L.P.

(Last) (First) (Middle)

300 TECHNOLOGY SQUARE, 8TH FLOOR

(Street)

CAMBRIDGE MA 02139

(City) (State) (Zip)

1. Name and Address of Reporting Person^*

ATLAS VENTURE ASSOCIATES X, L.P.

(Last) (First) (Middle)

300 TECHNOLOGY SQUARE, 8TH FLOOR

(Street)

CAMBRIDGE MA 02139

(City) (State) (Zip)

1. Name and Address of Reporting Person^*

Atlas Venture Associates X, LLC

(Last) (First) (Middle)

300 TECHNOLOGY SQUARE, 8TH FLOOR

(Street)

CAMBRIDGE MA 02139

(City) (State) (Zip)

1. Name and Address of Reporting Person^*

Atlas Venture Associates Opportunity I, LLC

(Last) (First) (Middle)

300 TECHNOLOGY SQUARE, 8TH FLOOR

(Street)

CAMBRIDGE MA 02139

(City) (State) (Zip)

1. Name and Address of Reporting Person^*

Atlas Venture Associates Opportunity I, L.P.

(Last) (First) (Middle)

300 TECHNOLOGY SQUARE, 8TH FLOOR

(Street)

CAMBRIDGE MA 02139

(City) (State) (Zip)

Explanation of Responses:

1. Each share of Series A Preferred Stock is automatically convertible into one share of Common Stock at the close of the Issuer's offering and has no expiration date.

2. The shares are held directly by Atlas Venture Fund XI, L.P. ("Fund XI"). The general partner of Fund XI is Atlas Venture Associates XI, L.P. ("AVA XI LP"). Atlas Venture Associates XI, LLC ("AVA XI LLC") is the general partner of AVA XI LP. Each of AVA XI LP and AVA XI LLC disclaims Section 16 beneficial ownership of the securities held by Fund XI, except to the extent of its pecuniary interest therein, if any.

3. Each share of Series B Preferred Stock is automatically convertible into one share of Common Stock at the close of the Issuer's offering and has no expiration date.

4. The shares are held directly by Atlas Venture Opportunity Fund I, L.P. ("Atlas Venture Opportunity Fund I"). The general partner of Atlas Venture Opportunity Fund I is Atlas Venture Associates Opportunity I, L.P. ("AVAO I LP"). Atlas Venture Associates Opportunity I, LLC ("AVAO I LLC") is the general partner of AVAO I LP. Each of AVAO I LP and AVAO I LLC disclaims Section 16 beneficial ownership of the securities held by Atlas Venture Opportunity Fund I, except to the extent of its pecuniary interest therein, if any.

Remarks:

	/s/ Ommer Chohan	05/26/2021
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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