[Form 4] Day One Biopharmaceuticals, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Day One Biopharmaceuticals (DAWN) filed a Form 4 showing an option repricing for a director. On 11/06/2025, fully vested stock options were repriced to an exercise price of $8.99, replacing prior grants with higher strike prices while keeping original terms and expirations. The transactions include exchanges of 63,000 (from $16; expiring 05/25/2031), 1,181 (from $16; 05/25/2031), 28,700 (from $16.29; 06/20/2032), 37,500 (from $12.69; 06/21/2033), and 32,335 (from $13.87; 05/22/2034) options, each reacquired at $8.99. The board approved the repricing on 10/07/2025. Exercising at the new price requires service through a “Retention Period” that ends on the earliest of the 12‑month anniversary of the effective date or a Corporate Transaction; other terms remain unchanged.

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^*

Josey John A.

(Last) (First) (Middle)

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)

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

3. Date of Earliest Transaction (Month/Day/Year)
11/06/2025

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)	$16	11/06/2025		D(1)(2)			63,000	(3)	05/25/2031	Common Stock	63,000	$0	0	D
Stock Option (right to buy Common Stock)	$8.99	11/06/2025		A(1)(2)		63,000		(3)	05/25/2031	Common Stock	63,000	$0	63,000	D
Stock Option (right to buy Common Stock)	$16	11/06/2025		D(1)(2)			1,181	(3)	05/25/2031	Common Stock	1,181	$0	0	D
Stock Option (right to buy Common Stock)	$8.99	11/06/2025		A(1)(2)		1,181		(3)	05/25/2031	Common Stock	1,181	$0	1,181	D
Stock Option (right to buy Common Stock)	$16.29	11/06/2025		D(1)(2)			28,700	(3)	06/20/2032	Common Stock	28,700	$0	0	D
Stock Option (right to buy Common Stock)	$8.99	11/06/2025		A(1)(2)		28,700		(3)	06/20/2032	Common Stock	28,700	$0	28,700	D
Stock Option (right to buy Common Stock)	$12.69	11/06/2025		D(1)(2)			37,500	(3)	06/21/2033	Common Stock	37,500	$0	0	D
Stock Option (right to buy Common Stock)	$8.99	11/06/2025		A(1)(2)		37,500		(3)	06/21/2033	Common Stock	37,500	$0	37,500	D
Stock Option (right to buy Common Stock)	$13.87	11/06/2025		D(1)(2)			32,335	(3)	05/22/2034	Common Stock	32,335	$0	0	D
Stock Option (right to buy Common Stock)	$8.99	11/06/2025		A(1)(2)		32,335		(3)	05/22/2034	Common Stock	32,335	$0	32,335	D

Explanation of Responses:

1. On October 7, 2025, the Issuer's Board of Directors approved an option repricing (the "Repricing") whereby the Reporting Person's options were repriced on November 6, 2025 (the "Effective Date") with a new exercise price of $8.99 (if lower than the original exercise price), the closing price on Nasdaq as of the Effective Date. In order to exercise the repriced options at the new exercise price, the Reporting Person is required to remain in service with the Issuer through the Retention Period; provided that the additional premium payment will not be required if the Reporting Person's service to the Issuer is terminated by reason of death or Disability (as defined in the Company's 2021 Equity Incentive Plan ("the Plan")).

2. (Continued from Footnote 1) The "Retention Period" commenced on the Effective Date and ends upon the earliest of (i) the 12-month anniversary of the Effective Date and (ii) a Corporate Transaction (as defined in the Plan). All of the other terms of the options remain unchanged. Such transactions were exempt pursuant to Rule 16b-6(d) and Rule 16b-3 of the Exchange Act, as applicable.

3. The options are fully vested.

	/s/ Charles N. York II, as Attorney-in-Fact	11/07/2025
	** 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 did Day One Biopharmaceuticals (DAWN) report in this Form 4?

A director’s stock options were repriced on 11/06/2025 to an exercise price of $8.99, with original terms and expirations unchanged.

Which option grants were affected for DAWN?

Exchanges included 63,000 (05/25/2031), 1,181 (05/25/2031), 28,700 (06/20/2032), 37,500 (06/21/2033), and 32,335 (05/22/2034) options.

What were the original exercise prices before the DAWN repricing?

Original strikes included $16, $16.29, $12.69, and $13.87, each replaced with a new exercise price of $8.99.

Were the repriced DAWN options vested?

Yes. The filing states the options are fully vested.

What conditions apply to exercising the new $8.99 DAWN options?

Exercise at $8.99 requires service through the “Retention Period,” ending at the earlier of 12 months from the effective date or a Corporate Transaction.

When was the DAWN option repricing approved?

The board approved the repricing on 10/07/2025.