Lauren Merendino - Feb 26, 2025 Form 3 Insider Report for Day One Biopharmaceuticals, Inc. (DAWN)

Role: Chief Commercial Officer
Signature: /s/ Charles N. York II, as Attorney-in-Fact
Stock symbol: DAWN
Transactions as of: Feb 26, 2025
Transactions value $: $0
Form type: 3
Date filed: 2/28/2025, 07:50 PM
Previous filing: Mar 28, 2024
Next filing: May 19, 2025
SEC: View on sec.gov

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
holding	DAWN	Common Stock						28.6K	Feb 26, 2025	Direct

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Underlying Class	Amount	Exercise Price	Ownership	Footnotes
holding	DAWN	Stock Option (right to buy Common Stock)							Feb 26, 2025	Common Stock	330K	$12.54	Direct	F1
holding	DAWN	Stock Option (right to buy Common Stock)							Feb 26, 2025	Common Stock	90K	$14.44	Direct	F2
holding	DAWN	Stock Option (right to buy Common Stock)							Feb 26, 2025	Common Stock	90K	$11.87	Direct	F3
holding	DAWN	Restricted Stock Units							Feb 26, 2025	Common Stock	31.6K		Direct	F4, F5, F6
holding	DAWN	Restricted Stock Units							Feb 26, 2025	Common Stock	40.6K		Direct	F5, F6, F7
holding	DAWN	Restricted Stock Units							Feb 26, 2025	Common Stock	55.3K		Direct	F5, F6, F8

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	The option vests as to 25% of the total shares on June 12, 2024 and then 2.0833% of the total shares vest monthly thereafter, with 100% of the total shares vested on June 12, 2027, subject to the Reporting Person's provision of service to the Issuer on each vesting date.
F2	The option vests as to 1/48th of the total shares monthly, commencing February 5, 2024, subject to the Reporting Person's provision of service to the Issuer on each vesting date.
F3	The option vests as to 1/48th of the total shares monthly, commencing February 15, 2025, subject to the Reporting Person's provision of service to the Issuer on each vesting date.
F4	The original award of 50,600 restricted stock units ("RSUs") was granted on June 12, 2023, of which 18,974 RSUs have previously vested and settled. The RSUs vested as to 1/4th of the total award on August 15, 2024, and the remaining 3/4 of the award vests in 12 substantially equal quarterly installments thereafter on November 15, February 15, May 15 and August 15, subject to the Reporting Person's provision of service to the Issuer on each vesting date.
F5	RSUs do not expire; they either vest or are canceled prior to the vesting date.
F6	Each RSU represents a contingent right to receive one share of the Issuer's Common Stock upon settlement.
F7	The original award of 59,000 RSUs was granted on January 5, 2024, of which 18,435 RSUs have previously vested and settled. The RSUs vest as to 1/16th of the total award in quarterly installments on February 15, May 15, August 15 and November 15, subject to the Reporting Person's provision of service to the Issuer on each vesting date.
F8	The original award of 59,000 RSUs was granted on January 15, 2025, of which 3,687 RSUs have previously vested and settled. The RSUs vest as to 1/16th of the total award in quarterly installments on February 15, May 15, August 15 and November 15, subject to the Reporting Person's provision of service to the Issuer on each vesting date.