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

Rhea-AI Filing Summary

Day One Biopharmaceuticals (DAWN): Director Form 4 discloses option repricing. On 11/06/2025, two stock option grants were repriced to an exercise price of $8.99, equal to the Nasdaq closing price on the effective date if lower than the original price.

The actions replaced options for 66,660 shares at $13.81 and 32,335 shares at $13.87 with new options at $8.99. To exercise the repriced options, the reporting person must remain in service through the Retention Period, ending on the earlier of the 12‑month anniversary of the effective date or a Corporate Transaction. One grant vests 1/36 monthly beginning 02/17/2024; the other is fully vested.

Insights

Equity compensation analyst

Administrative option repricing to $8.99; neutral impact.

DAWN repriced two director option grants effective 11/06/2025 to an exercise price of $8.99 if below the originals. The changes swap prior strikes of $13.81 (66,660 options) and $13.87 (32,335 options) for the new price, with other terms unchanged.

The filing specifies a Retention Period that must elapse before exercise at the new price, ending at the earlier of the 12‑month anniversary of the effective date or a Corporate Transaction. One award vests 1/36 monthly starting 02/17/2024; the other is fully vested.

This is a routine compensation adjustment exempt under Rule 16b‑6(d) and Rule 16b‑3. Actual exercise timing depends on service through the Retention Period and award terms.

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

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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^*

Dable Habib J

(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)	$13.81	11/06/2025		D(1)(2)			66,660	(3)	01/16/2034	Common Stock	66,660	$0	0	D
Stock Option (right to buy Common Stock)	$8.99	11/06/2025		A(1)(2)		66,660		(3)	01/16/2034	Common Stock	66,660	$0	66,660	D
Stock Option (right to buy Common Stock)	$13.87	11/06/2025		D(1)(2)			32,335	(4)	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		(4)	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 option vests as to 1/36th of the total shares on each monthly anniversary, beginning on February 17, 2024, subject to the Reporting Person's provision of service to the Issuer on each vesting date.

4. 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).
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FAQ

What did Day One Biopharmaceuticals (DAWN) disclose in this Form 4?

A director’s stock options were repriced effective 11/06/2025 to an exercise price of $8.99, if lower than the original price.

Which option grants were affected for DAWN?

Two grants: 66,660 options originally at $13.81 and 32,335 options originally at $13.87, both repriced to $8.99.

What is the Retention Period requirement for the repriced options (DAWN)?

Service must continue through the earlier of the 12-month anniversary of the effective date or a Corporate Transaction.

What are the vesting terms of the affected DAWN options?

One option vests 1/36 monthly starting 02/17/2024; the other option is fully vested.

Did other terms of the DAWN options change in the repricing?

No. The filing states all other terms of the options remain unchanged and cites exemptions under Rule 16b-6(d) and Rule 16b-3.

Who is the reporting person’s relationship to DAWN?

The reporting person is a Director, and the form was filed by one reporting person.