David Tsao - 03 Sep 2026 Form 4 Insider Report for BillionToOne, Inc. (BLLN)

Reporting relationship: Chief Technology Officer, Director
Issuer ticker: BLLN
Reported as of: 03 Sep 2026
Net transaction value: $0
SEC form: 4
Accepted by SEC: 08 Sep 2026, 21:55:50 UTC
Prior SEC filing: 27 Aug 2026
Next SEC filing: 11 Sep 2026
Source filing: View source filing
Reporting owner signature: /s/ Thomas P. Lynch, Attorney-in-Fact

Key filing fact

David Tsao filed Form 4 for BillionToOne, Inc. (BLLN) on 08 Sep 2026.

Key facts

This page summarizes David Tsao's Form 4 filing for BillionToOne, Inc. (BLLN).
3 reported transactions and 1 derivative row are listed below.
Accepted by SEC: 08 Sep 2026, 21:55.

Change

Previous filing in this sequence was filed on 27 Aug 2026.
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 0002087127 Primary reporting owner

Tsao David

Relationship: Chief Technology Officer, Director
Address: C/O BILLIONTOONE, INC., 1035 O'BRIEN DRIVE, MENLO PARK
Signature: /s/ Thomas P. Lynch, Attorney-in-Fact
Signature date: 08 Sep 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

BLLN transaction

Class A Common Stock

Conversion of derivative security

Transaction value
Shares: +20,000
Change %: +2000%
Price: $0.000000^*
Shares after: 21,000
Date: 03 Sep 2026
Ownership: Direct
Footnotes: F1

BLLN transaction

Class A Common Stock

Gift

Transaction value
Shares: -20,000
Change %: -95%
Price: $0.000000^*
Shares after: 1,000
Date: 08 Sep 2026
Ownership: Direct

Reported derivative securities

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

BLLN transaction Derivative

Class B Common Stock

Conversion of derivative security

Transaction value
Shares: -20,000
Change %: -0.86%
Price: $0.000000^*
Shares after: 2,305,108
Date: 03 Sep 2026
Ownership: Direct
Underlying class: Class A Common Stock
Underlying amount: 20,000
Exercise price
Footnotes: F1, F2

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

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 2 footnotes

Footnote F1

These shares of Class B common stock were converted at a 1:1 ratio for shares of Class A common stock at the option of the holder.

Footnote F2

Each share of Class B Common Stock is convertible into one share of Class A common stock at the option of the holder. Class B common stock will convert automatically on a one-for-one basis into shares of the Issuer's Class A common stock upon the earliest of (i) seven years from the date of filing of the amended and restated certificate of incorporation, in connection with the Offering and (ii) the date specified by a vote of the holders of Class B common stock representing a majority of the outstanding shares of Class B common stock.