Thomas S. Bremner - 05 Nov 2025 Form 3 Insider Report for BillionToOne, Inc.

Role
Director
Signature
/s/ Thomas P. Lynch, Attorney-in-Fact
Issuer symbol
BLLN on Nasdaq
Transactions as of
05 Nov 2025
Net transactions value
$0
Form type
3
Filing time
05 Nov 2025, 21:30:08 UTC
Next filing
10 Nov 2025
SEC
View on sec.gov

Reporting Owners (1)

Name Relationship Address Signature Signature date CIK
Bremner Thomas S Director 1 NORTH WACKER DRIVE, SUITE 2200, CHICAGO /s/ Thomas P. Lynch, Attorney-in-Fact 05 Nov 2025 0002087538

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Underlying Class Amount Exercise Price Ownership Footnotes
holding BLLN Series A-1 Convertible Preferred Stock 05 Nov 2025 Common Stock 1,352 See footnotes F1, F2, F9, F10
holding BLLN Series C Convertible Preferred Stock 05 Nov 2025 Common Stock 114,117 See footnotes F1, F2, F9, F10
holding BLLN Series C-1 Convertible Preferred Stock 05 Nov 2025 Common Stock 16,747 See footnotes F1, F2, F9, F10
holding BLLN Series D Convertible Preferred Stock 05 Nov 2025 Common Stock 20,224 See footnotes F1, F2, F9, F10
holding BLLN Series C Convertible Preferred Stock 05 Nov 2025 Common Stock 121,688 See footnotes F1, F3, F9, F10
holding BLLN Series C-1 Convertible Preferred Stock 05 Nov 2025 Common Stock 17,858 See footnotes F1, F3, F9, F10
holding BLLN Series D Convertible Preferred Stock 05 Nov 2025 Common Stock 16,165 See footnotes F1, F3, F9, F10
holding BLLN Series A-1 Convertible Preferred Stock 05 Nov 2025 Common Stock 1,562 See footnotes F1, F4, F9, F10
holding BLLN Series C Convertible Preferred Stock 05 Nov 2025 Common Stock 131,888 See footnotes F1, F4, F9, F10
holding BLLN Series C-1 Convertible Preferred Stock 05 Nov 2025 Common Stock 19,355 See footnotes F1, F4, F9, F10
holding BLLN Series D Convertible Preferred Stock 05 Nov 2025 Common Stock 23,466 See footnotes F1, F4, F9, F10
holding BLLN Series A-1 Convertible Preferred Stock 05 Nov 2025 Common Stock 1,864 See footnotes F1, F5, F9, F10
holding BLLN Series C Convertible Preferred Stock 05 Nov 2025 Common Stock 157,404 See footnotes F1, F5, F9, F10
holding BLLN Series C-1 Convertible Preferred Stock 05 Nov 2025 Common Stock 23,100 See footnotes F1, F5, F9, F10
holding BLLN Series D Convertible Preferred Stock 05 Nov 2025 Common Stock 87,550 See footnotes F1, F5, F9, F10
holding BLLN Series A-1 Convertible Preferred Stock 05 Nov 2025 Common Stock 652 See footnotes F1, F6, F9, F10
holding BLLN Series C Convertible Preferred Stock 05 Nov 2025 Common Stock 55,091 See footnotes F1, F6, F9, F10
holding BLLN Series C-1 Convertible Preferred Stock 05 Nov 2025 Common Stock 8,084 See footnotes F1, F6, F9, F10
holding BLLN Series D Convertible Preferred Stock 05 Nov 2025 Common Stock 176,245 See footnotes F1, F6, F9, F10
holding BLLN Series A-1 Convertible Preferred Stock 05 Nov 2025 Common Stock 5,988 See footnotes F1, F7, F9, F10
holding BLLN Series C Convertible Preferred Stock 05 Nov 2025 Common Stock 505,570 See footnotes F1, F7, F9, F10
holding BLLN Series C-1 Convertible Preferred Stock 05 Nov 2025 Common Stock 74,195 See footnotes F1, F7, F9, F10
holding BLLN Series D Convertible Preferred Stock 05 Nov 2025 Common Stock 89,599 See footnotes F1, F7, F9, F10
holding BLLN Series A-1 Convertible Preferred Stock 05 Nov 2025 Common Stock 1,078 See footnotes F1, F8, F9, F10
holding BLLN Series C Convertible Preferred Stock 05 Nov 2025 Common Stock 91,003 See footnotes F1, F8, F9, F10
holding BLLN Series C-1 Convertible Preferred Stock 05 Nov 2025 Common Stock 13,355 See footnotes F1, F8, F9, F10
holding BLLN Series D Convertible Preferred Stock 05 Nov 2025 Common Stock 122,072 See footnotes F1, F8, F9, F10
* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id Content
F1 The reported security is convertible into the Issuer's Common Stock on a one-for-one basis at any time at the holder's election and shall automatically convert into Class A common stock immediately prior to the closing of the Issuer's initial public offering of Class A common stock without payment of further consideration. The shares have no expiration date.
F2 The reported security is directly held by Adams Street 2019 Direct Growth Equity Fund LP.
F3 The reported security is directly held by Adams Street 2020 Direct Growth Equity Fund LP.
F4 The reported security is directly held by Adams Street 2021 Direct Growth Equity Fund LP.
F5 The reported security is directly held by Adams Street 2022 Direct Growth Equity Fund LP.
F6 The reported security is directly held by Adams Street Private Equity Navigator Fund LLC (f/k/a Adams Street Global Private Markets Fund LP).
F7 The reported security is directly held by Adams Street Growth Equity Fund VII LP.
F8 The reported security is directly held by FCPR GF-Lumyna Private Equity World Fund.
F9 Adams Street Partners, LLC is the managing member of the general partner of each of Adams Street 2019 Direct Growth Equity Fund LP, Adams Street 2020 Direct Growth Equity Fund LP, Adams Street 2021 Direct Growth Equity Fund LP, Adams Street 2022 Direct Growth Equity Fund LP, Adams Street Growth Equity Fund VII LP, and Adams Street Private Equity Navigator Fund LLC (f/k/a Adams Street Global Private Markets Fund LP) (collectively, the U.S. Funds) and, as a result, may be deemed to beneficially own the shares held by the U.S. Funds. Furthermore, Adams Street Partners, LLC, is the Sous-Delegataire Financier of the Delegataire Financier of the management company of FCPR GF-Lumyna Private Equity World Fund (Lumyna and together with the U.S. Funds, the Funds) and, as a result,
F10 (Continued from footnote 9) may be deemed to beneficially own the shares held by Lumyna. Thomas S. Bremner, Jeffrey T. Diehl, Brian Dudley, Elisha P. Gould, Robin Murray and Fred Wang, each of whom is a partner of Adams Street Partners, LLC (or a subsidiary thereof), may be deemed to have shared voting, investment and dispositive power over the shares held by the Funds. The Reporting Person disclaims beneficial ownership of these shares except to the extent of his pecuniary interest therein.

Remarks:

Exhibit 24 - Power of Attorney