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

Rhea-AI Filing Summary

Day One Biopharmaceuticals insider transactions: Adam Dubow, listed as the issuer's General Counsel & Secretary and an officer, had multiple Restricted Stock Units (RSUs) settle on 08/15/2025, resulting in the acquisition of 11,087 shares of common stock through four RSU settlements and increasing his reported beneficial ownership in steps to 59,223 shares before a subsequent sale. On 08/18/2025 Dubow sold 4,365 shares in a block trade at a weighted average price of $6.7671 per share; the filing states the sale was made solely to cover tax liabilities related to the RSU settlements. The filing discloses vesting schedules for the RSUs (initial 25% vesting on 11/15/2023, then quarterly installments or 1/16th per quarter as specified) and confirms RSUs convert to one share each upon settlement for no consideration.

Positive

• RSU settlements documented: 11,087 shares acquired via RSU vesting on 08/15/2025, showing executive equity alignment with the company.
• Clear vesting schedule disclosed: Initial 25% vesting on 11/15/2023 with subsequent quarterly vesting, providing transparency on future potential dilution timing.

Negative

• Insider sale reported: 4,365 shares sold on 08/18/2025 at a weighted average price of $6.7671, which reduces the reporting person's direct holdings to 54,858 shares.

Insights

Securities Analyst

TL;DR: Insider received RSUs that vested and sold a portion to cover taxes; transaction appears routine and not an unexpected change in control.

The filing documents customary equity compensation settlements and a small related sale to satisfy tax withholding. Total shares acquired via RSU settlement on 08/15/2025 amounted to 11,087 shares across four grants, and 4,365 shares were sold on 08/18/2025 at a weighted average price of $6.7671. The sale is explicitly described as solely for tax purposes. From an investor-significance perspective, these actions reflect compensation mechanics rather than a change in strategic ownership or corporate control and thus are neutral for valuation absent other disclosures.

Corporate Governance Expert

TL;DR: The Form 4 shows standard executive equity vesting and a tax-related disposition; no governance red flags are evident from the filing alone.

The report lists Adam Dubow as an officer (General Counsel & Secretary). Multiple RSUs vested with specific schedules and no expiration, and settlement mechanics are disclosed (one RSU equals one share). The filing includes an attorney-in-fact signature, indicating procedural completeness. There are no indications of related-party transactions beyond ordinary compensation, no accelerated vesting triggers disclosed, and the sale is limited to tax withholding—consistent with typical executive equity administration.

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
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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^*

Dubow Adam

(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)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Gen Counsel & Secretary

3. Date of Earliest Transaction (Month/Day/Year)
08/15/2025

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
Common Stock	08/15/2025		M		2,963	A	(1)	50,099	D
Common Stock	08/15/2025		M		1,750	A	(1)	51,849	D
Common Stock	08/15/2025		M		3,687	A	(1)	55,536	D
Common Stock	08/15/2025		M		3,687	A	(1)	59,223	D
Common Stock	08/18/2025		S(2)		4,365	D	$6.7671(3)	54,858	D

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
Restricted Stock Unit (RSU)	(1)	08/15/2025		M			2,963	(4)	(5)	Common Stock	2,963	$0	14,815	D
Restricted Stock Unit (RSU)	(1)	08/15/2025		M			1,750	(6)	(5)	Common Stock	1,750	$0	8,750	D
Restricted Stock Unit (RSU)	(1)	08/15/2025		M			3,687	(6)	(5)	Common Stock	3,687	$0	33,191	D
Restricted Stock Unit (RSU)	(1)	08/15/2025		M			3,687	(6)	(5)	Common Stock	3,687	$0	47,939	D

Explanation of Responses:

1. Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of the Issuer's Common Stock upon settlement for no consideration.

2. The sale of shares is for the sole purpose of covering the Reporting Person's tax liability with respect to the settlement of RSUs.

3. The price reported in Column 4 is a weighted average price. These shares were sold as part of block trades for multiple security holders of the Issuer at prices ranging from $6.65 to $6.87, inclusive. The Reporting Person undertakes to provide to the Issuer, any securityholder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth herein with regard to the block trade.

4. The RSUs vest as to 25% of the total award on November 15, 2023, and 1/12th of the remaining amount vest in quarterly installments thereafter 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.

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

6. The RSUs will 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.

	/s/ Charles N. York II, as Attorney-in-Fact	08/19/2025
	** 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 insider transactions did DAWN report on this Form 4?

Adam Dubow had RSUs settle on 08/15/2025 totaling 11,087 shares acquired and sold 4,365 shares on 08/18/2025 at a weighted average price of $6.7671.

Why were shares sold by the reporting person in the DAWN Form 4?

The filing states the sale was made solely to cover tax liability arising from the RSU settlements.

What is Adam Dubow's role at Day One Biopharma as reported?

The Form 4 lists Adam Dubow as an Officer with the title General Counsel & Secretary.

How many shares does the filing show after the reported transactions?

Following the reported transactions, the filing shows the reporting person beneficially owned 54,858 shares after the 08/18/2025 sale.

What are the RSU vesting terms disclosed in the filing?

RSUs vest 25% on 11/15/2023 with the remainder vesting in quarterly installments (Feb 15, May 15, Aug 15, Nov 15) or per a 1/16th quarterly schedule as specified.