Day One Strengthens Research Leadership with Major Equity Package

Rhea-AI Filing Summary

Day One Biopharmaceuticals reported insider trading activity for Michael Vasconcelles, Head of Research and Development, who received significant equity compensation on June 16, 2025:

• Stock Options: Granted 346,000 options to purchase common stock at $6.64 per share, vesting over 4 years (25% after first year, then monthly)
• Restricted Stock Units (RSUs): Awarded 226,000 RSUs with zero exercise price, vesting over approximately 4 years (25% in August 2026, remaining quarterly)

The equity grants suggest a long-term retention strategy for this key executive, with the options expiring June 15, 2035. The combined award of performance-based options and time-vested RSUs represents a significant compensation package aimed at aligning the executive's interests with shareholders while providing both upside potential and guaranteed value through RSUs.

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^*

VASCONCELLES MICHAEL

(Last) (First) (Middle)

C/O DAY ONE BIOPHARMACEUTICALS, INC.

1800 SIERRA POINT PARKWAY, SUITE 200

(Street)

BRISBANE CA 94005

(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		10% Owner
X	Officer (give title below)		Other (specify below)
	Head of Research and Dev.

3. Date of Earliest Transaction (Month/Day/Year)
06/16/2025

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

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
Stock Option (right to buy Common Stock)	$6.64	06/16/2025		A		346,000		(1)	06/15/2035	Common Stock	346,000	$0	346,000	D
Restricted Stock Unit (RSU)	$0(2)	06/16/2025		A		226,000		(3)	(4)	Common Stock	226,000	$0	226,000	D

Explanation of Responses:

1. The option vests as to 1/4th of the total grant on June 16, 2026, and 1/48th of the total grant will vest on each monthly anniversary thereafter, subject to the Reporting Person's provision of service to the Issuer on each option vesting date.

2. Each restricted stock unit ("RSU") represents a contingent right to receive one share of the Issuer's Common Stock upon settlement for no consideration.

3. The RSUs vest as to 25% of the total award on August 15, 2026, and 1/12th of the remaining RSUs vest in 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 RSU vesting date.

4. RSUs do not expire; they either vest or are canceled prior to the RSU vesting date..

	/s/ Charles N. York II, as Attorney-in-Fact	06/18/2025
	** 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 Number.

FAQ

What stock options did DAWN's Head of Research and Development receive in June 2025?

Michael Vasconcelles, DAWN's Head of Research and Development, received stock options to purchase 346,000 shares of common stock at an exercise price of $6.64 per share on June 16, 2025. The options vest over 4 years, with 25% vesting on June 16, 2026, and 1/48th vesting monthly thereafter. The options expire on June 15, 2035.

How many RSUs were granted to DAWN's Head of R&D in the latest Form 4?

According to the Form 4 filing, Michael Vasconcelles received 226,000 Restricted Stock Units (RSUs) on June 16, 2025. These RSUs vest over time with 25% vesting on August 15, 2026, and the remaining RSUs vesting in quarterly installments thereafter on November 15, February 15, May 15, and August 15.

What is the vesting schedule for DAWN executive's June 2025 stock options?

The stock options granted to DAWN's executive vest over a 4-year period: 25% (one-fourth) of the total 346,000 options vest on June 16, 2026 (first anniversary), followed by 1/48th of the total grant vesting each month thereafter. The vesting is subject to the executive's continued service with the company on each vesting date.

When do DAWN's June 2025 RSUs granted to Michael Vasconcelles vest?

The RSUs granted to Michael Vasconcelles vest according to the following schedule: 25% of the 226,000 RSUs vest on August 15, 2026, with the remaining RSUs vesting in quarterly installments on November 15, February 15, May 15, and August 15 thereafter. Vesting is contingent upon continued service with DAWN on each vesting date.