Michael Vasconcelles - 30 Jan 2026 Form 4 Insider Report for Day One Biopharmaceuticals, Inc. (DAWN)

Reporting relationship: Head of Research and Dev.
Issuer ticker: DAWN
Reported as of: 30 Jan 2026
Net transaction value: $0
SEC form: 4
Accepted by SEC: 30 Jan 2026, 17:18:48 UTC
Prior SEC filing: 18 Jun 2025
Next SEC filing: 18 Feb 2026
Source filing: View source filing
Reporting owner signature: /s/ Charles N. York II, as Attorney-in-Fact

Key filing fact

Michael Vasconcelles filed Form 4 for Day One Biopharmaceuticals, Inc. (DAWN) on 30 Jan 2026.

Key facts

This page summarizes Michael Vasconcelles's Form 4 filing for Day One Biopharmaceuticals, Inc. (DAWN).
2 reported transactions and 2 derivative rows are listed below.
Accepted by SEC: 30 Jan 2026, 17:18.

Change

Previous filing in this sequence was filed on 18 Jun 2025.
Current net transaction value: $0.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001734755 Primary reporting owner

VASCONCELLES MICHAEL

Relationship: Head of Research and Dev.
Address: 1800 SIERRA POINT PARKWAY, SUITE 200, BRISBANE
Signature: /s/ Charles N. York II, as Attorney-in-Fact
Signature date: 30 Jan 2026

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

DAWN transaction Derivative

Stock Option (right to buy Common Stock)

Award

Transaction value: $0
Shares: +171,000
Change %
Price: $0.000000
Shares after: 171,000
Date: 30 Jan 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 171,000
Exercise price: $11.16
Footnotes: F1

DAWN transaction Derivative

Restricted Stock Units

Award

Transaction value: $0
Shares: +114,000
Change %
Price: $0.000000
Shares after: 114,000
Date: 30 Jan 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 114,000
Exercise price
Footnotes: F2, F3, F4

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 4 footnotes

Footnote F1

The option vests as to 1/48th of the total shares monthly, commencing February 28, 2026, subject to the Reporting Person's provision of service to the Issuer on each vesting date.

Footnote F2

Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of the Issuer's Common Stock upon settlement.

Footnote F3

The RSUs 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.

Footnote F4

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