Day One (NASDAQ: DAWN) CFO-COO sells shares to cover RSU taxes

Rhea-AI Filing Summary

Day One Biopharmaceuticals COO and CFO Charles N. York II reported a mix of stock sales and equity award settlements. He sold 6,065 shares of Common Stock in an open-market transaction at a weighted average price of $11.6009 per share. A footnote states this sale was solely to cover his tax liability arising from restricted stock unit (RSU) settlements.

On the same general timeline, he exercised and settled multiple RSU awards, each representing a right to receive one share of Common Stock for no cash consideration. The RSUs vest quarterly in 1/16th increments on February 15, May 15, August 15 and November 15, as long as he continues providing service to the company.

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^*

York Charles N II

(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)
	COO and CFO

3. Date of Earliest Transaction (Month/Day/Year)
02/15/2026

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	02/15/2026		M		2,250	A	(1)	296,965	D
Common Stock	02/15/2026		M		6,625	A	(1)	303,590	D
Common Stock	02/15/2026		M		6,625	A	(1)	310,215	D
Common Stock	02/15/2026		M		7,875	A	(1)	318,090	D
Common Stock	02/17/2026		S(2)		6,065	D	$11.6009(3)	312,025	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)	02/15/2026		M			2,250	(4)	(5)	Common Stock	2,250	$0	6,750	D
Restricted Stock Unit (RSU)	(1)	02/15/2026		M			6,625	(4)	(5)	Common Stock	6,625	$0	46,375	D
Restricted Stock Unit (RSU)	(1)	02/15/2026		M			6,625	(4)	(5)	Common Stock	6,625	$0	72,875	D
Restricted Stock Unit (RSU)	(1)	02/15/2026		M			7,875	(4)	(5)	Common Stock	7,875	$0	118,125	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 $11.195 to $11.8508, 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 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.

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

	/s/ Charles N. York II	02/18/2026
	** 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 executive Charles N. York II report?

He reported an open-market sale of 6,065 shares of Common Stock and multiple restricted stock unit (RSU) settlements. The sale was disclosed as covering tax liabilities from those RSU settlements, while the RSUs converted into shares for no cash consideration.

How many Day One Biopharmaceuticals shares did the DAWN COO and CFO sell?

He sold 6,065 shares of Day One Biopharmaceuticals Common Stock. The transaction used a weighted average price of $11.6009 per share, reflecting block trades executed within a disclosed price range for multiple security holders during the sale process.

Why did the DAWN executive sell shares in this Form 4 filing?

A footnote explains the sale was solely to cover his tax liability from the settlement of RSUs. This means the transaction was linked to equity compensation vesting rather than a discretionary decision to reduce overall economic exposure.

How do the RSUs in this DAWN Form 4 vest over time?

The RSUs vest in 1/16th increments of the total award on February 15, May 15, August 15 and November 15. Vesting continues only if the executive remains in service to Day One Biopharmaceuticals on each applicable vesting date.

What does each DAWN restricted stock unit (RSU) represent for the holder?

Each RSU represents a contingent right to receive one share of Day One Biopharmaceuticals Common Stock for no cash consideration. RSUs do not expire; they either vest into shares or are canceled if vesting conditions are not satisfied before the scheduled dates.

What was the price range for the DAWN insider’s stock sale?

The reported weighted average price was $11.6009 per share. Footnote disclosure states the block trades for multiple holders occurred at prices ranging from $11.195 to $11.8508, and detailed trade breakdowns are available on request from the company or regulators.