Thomas S. Bremner - 06 Nov 2025 Form 4 Insider Report for BillionToOne, Inc.

Role
Director
Signature
/s/ Thomas P. Lynch, Attorney-in-Fact
Issuer symbol
BLLN on Nasdaq
Transactions as of
06 Nov 2025
Net transactions value
+$2,499,960
Form type
4
Filing time
10 Nov 2025, 21:38:40 UTC
Previous filing
05 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 10 Nov 2025 0002087538

Transactions Table

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Ownership Footnotes
transaction BLLN Common Stock Award $0 +8,333 $0.000000 8,333 06 Nov 2025 Direct F1
transaction BLLN Common Stock Conversion of derivative security +152,440 152,440 07 Nov 2025 See Footnotes F2, F3, F4, F11, F12
transaction BLLN Common Stock Conversion of derivative security +155,711 155,711 07 Nov 2025 See Footnotes F2, F3, F5, F11, F12
transaction BLLN Common Stock Conversion of derivative security +176,271 176,271 07 Nov 2025 See Footnotes F2, F3, F6, F11, F12
transaction BLLN Common Stock Conversion of derivative security +269,918 269,918 07 Nov 2025 See Footnotes F2, F3, F7, F11, F12
transaction BLLN Common Stock Conversion of derivative security +240,072 240,072 07 Nov 2025 See Footnotes F2, F3, F8, F11, F12
transaction BLLN Common Stock Conversion of derivative security +675,352 675,352 07 Nov 2025 See Footnotes F2, F3, F9, F11, F12
transaction BLLN Common Stock Conversion of derivative security +277,508 277,508 07 Nov 2025 See Footnotes F2, F3, F10, F11, F12
transaction BLLN Common Stock Other -8,333 -100% 0 07 Nov 2025 Direct F13
transaction BLLN Common Stock Other -152,440 -100% 0 07 Nov 2025 See Footnotes F4, F11, F12, F13
transaction BLLN Common Stock Other -155,711 -100% 0 07 Nov 2025 See Footnotes F5, F11, F12, F13
transaction BLLN Common Stock Other -176,271 -100% 0 07 Nov 2025 See Footnotes F6, F11, F12, F13
transaction BLLN Common Stock Other -269,918 -100% 0 07 Nov 2025 See Footnotes F7, F11, F12, F13
transaction BLLN Common Stock Other -240,072 -100% 0 07 Nov 2025 See Footnotes F8, F11, F12, F13
transaction BLLN Common Stock Other -675,352 -100% 0 07 Nov 2025 See Footnotes F9, F11, F12, F13
transaction BLLN Common Stock Other -277,508 -100% 0 07 Nov 2025 See Footnotes F10, F11, F12, F13
transaction BLLN Class A Common Stock Other +8,333 8,333 07 Nov 2025 Direct F13
transaction BLLN Class A Common Stock Other +152,440 152,440 07 Nov 2025 See Footnotes F4, F11, F12, F13
transaction BLLN Class A Common Stock Other +155,711 155,711 07 Nov 2025 See Footnotes F5, F11, F12, F13
transaction BLLN Class A Common Stock Other +176,271 176,271 07 Nov 2025 See Footnotes F6, F11, F12, F13
transaction BLLN Class A Common Stock Other +269,918 269,918 07 Nov 2025 See Footnotes F7, F11, F12, F13
transaction BLLN Class A Common Stock Other +240,072 240,072 07 Nov 2025 See Footnotes F8, F11, F12, F13
transaction BLLN Class A Common Stock Other +675,352 675,352 07 Nov 2025 See Footnotes F9, F11, F12, F13
transaction BLLN Class A Common Stock Other +277,508 277,508 07 Nov 2025 See Footnotes F10, F11, F12, F13
transaction BLLN Class A Common Stock Purchase $240,960 +4,016 +2.6% $60.00* 156,456 07 Nov 2025 See Footnotes F4, F11, F12
transaction BLLN Class A Common Stock Purchase $245,040 +4,084 +2.6% $60.00* 159,795 07 Nov 2025 See Footnotes F5, F11, F12
transaction BLLN Class A Common Stock Purchase $207,720 +3,462 +2% $60.00* 179,733 07 Nov 2025 See Footnotes F6, F11, F12
transaction BLLN Class A Common Stock Purchase $326,760 +5,446 +2% $60.00* 275,364 07 Nov 2025 See Footnotes F7, F11, F12
transaction BLLN Class A Common Stock Purchase $412,020 +6,867 +2.9% $60.00* 246,939 07 Nov 2025 See Footnotes F8, F11, F12
transaction BLLN Class A Common Stock Purchase $1,067,460 +17,791 +2.6% $60.00* 693,143 07 Nov 2025 See Footnotes F9, F11, F12

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
transaction BLLN Series A-1 Convertible Preferred Stock Conversion of derivative security -1,352 -100% 0 07 Nov 2025 Common Stock 1,352 See Footnotes F3, F4, F11, F12
transaction BLLN Series C Convertible Preferred Stock Conversion of derivative security -114,117 -100% 0 07 Nov 2025 Common Stock 114,117 See Footnotes F3, F4, F11, F12
transaction BLLN Series C-1 Convertible Preferred Stock Conversion of derivative security -16,747 -100% 0 07 Nov 2025 Common Stock 16,747 See Footnotes F3, F4, F11, F12
transaction BLLN Series D Convertible Preferred Stock Conversion of derivative security -20,224 -100% 0 07 Nov 2025 Common Stock 20,224 See Footnotes F3, F4, F11, F12
transaction BLLN Series C Convertible Preferred Stock Conversion of derivative security -121,688 -100% 0 07 Nov 2025 Common Stock 121,688 See Footnotes F3, F5, F11, F12
transaction BLLN Series C-1 Convertible Preferred Stock Conversion of derivative security -17,858 -100% 0 07 Nov 2025 Common Stock 17,858 See Footnotes F3, F5, F11, F12
transaction BLLN Series D Convertible Preferred Stock Conversion of derivative security -16,165 -100% 0 07 Nov 2025 Common Stock 16,165 See Footnotes F3, F5, F11, F12
transaction BLLN Series A-1 Convertible Preferred Stock Conversion of derivative security -1,562 -100% 0 07 Nov 2025 Common Stock 1,562 See Footnotes F3, F6, F11, F12
transaction BLLN Series C Convertible Preferred Stock Conversion of derivative security -131,888 -100% 0 07 Nov 2025 Common Stock 131,888 See Footnotes F3, F6, F11, F12
transaction BLLN Series C-1 Convertible Preferred Stock Conversion of derivative security -19,355 -100% 0 07 Nov 2025 Common Stock 19,355 See Footnotes F3, F6, F11, F12
transaction BLLN Series D Convertible Preferred Stock Conversion of derivative security -23,466 -100% 0 07 Nov 2025 Common Stock 23,466 See Footnotes F3, F6, F11, F12
transaction BLLN Series A-1 Convertible Preferred Stock Conversion of derivative security -1,864 -100% 0 07 Nov 2025 Common Stock 1,864 See Footnotes F3, F7, F11, F12
transaction BLLN Series C Convertible Preferred Stock Conversion of derivative security -157,404 -100% 0 07 Nov 2025 Common Stock 157,404 See Footnotes F3, F7, F11, F12
transaction BLLN Series C-1 Convertible Preferred Stock Conversion of derivative security -23,100 -100% 0 07 Nov 2025 Common Stock 23,100 See Footnotes F3, F7, F11, F12
transaction BLLN Series D Convertible Preferred Stock Conversion of derivative security -87,550 -100% 0 07 Nov 2025 Common Stock 87,550 See Footnotes F3, F7, F11, F12
transaction BLLN Series A-1 Convertible Preferred Stock Conversion of derivative security -652 -100% 0 07 Nov 2025 Common Stock 652 See Footnotes F3, F8, F11, F12
transaction BLLN Series C Convertible Preferred Stock Conversion of derivative security -55,091 -100% 0 07 Nov 2025 Common Stock 55,091 See Footnotes F3, F8, F11, F12
transaction BLLN Series C-1 Convertible Preferred Stock Conversion of derivative security -8,084 -100% 0 07 Nov 2025 Common Stock 8,084 See Footnotes F3, F8, F11, F12
transaction BLLN Series D Convertible Preferred Stock Conversion of derivative security -176,245 -100% 0 07 Nov 2025 Common Stock 176,245 See Footnotes F3, F8, F11, F12
transaction BLLN Series A-1 Convertible Preferred Stock Conversion of derivative security -5,988 -100% 0 07 Nov 2025 Common Stock 5,988 See Footnotes F3, F9, F11, F12
transaction BLLN Series C Convertible Preferred Stock Conversion of derivative security -505,570 -100% 0 07 Nov 2025 Common Stock 505,570 See Footnotes F3, F9, F11, F12
transaction BLLN Series C-1 Convertible Preferred Stock Conversion of derivative security -74,195 -100% 0 07 Nov 2025 Common Stock 74,195 See Footnotes F3, F9, F11, F12
transaction BLLN Series D Convertible Preferred Stock Conversion of derivative security -89,599 -100% 0 07 Nov 2025 Common Stock 89,599 See Footnotes F3, F9, F11, F12
transaction BLLN Series A-1 Convertible Preferred Stock Conversion of derivative security -1,078 -100% 0 07 Nov 2025 Common Stock 1,078 See Footnotes F3, F10, F11, F12
transaction BLLN Series C Convertible Preferred Stock Conversion of derivative security -91,003 -100% 0 07 Nov 2025 Common Stock 91,003 See Footnotes F3, F10, F11, F12
transaction BLLN Series C-1 Convertible Preferred Stock Conversion of derivative security -13,355 -100% 0 07 Nov 2025 Common Stock 13,355 See Footnotes F3, F10, F11, F12
transaction BLLN Series D Convertible Preferred Stock Conversion of derivative security -122,072 -100% 0 07 Nov 2025 Common Stock 122,072 See Footnotes F3, F10, F11, F12
* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id Content
F1 Each restricted stock unit ("RSU") represents a contingent right to receive one share of the Issuer's Common Stock. The RSUs shall vest over three years in equal annual installments on the anniversary of November 6, 2025, subject to the Reporting Person's continuous service to the Issuer through each such vesting date.
F2 The total represents shares received upon conversion of shares of Series A-1 Convertible Preferred Stock, Series C Convertible Preferred Stock, Series C-1 Convertible Preferred Stock and/or Series D Convertible Preferred Stock.
F3 The reported security converted into the Issuer's Common Stock on a one-for-one basis automatically immediately prior to the closing of the Issuer's initial public offering of Class A common stock (the "Offering") without payment of further consideration. The shares have no expiration date.
F4 The reported security is directly held by Adams Street 2019 Direct Growth Equity Fund LP.
F5 The reported security is directly held by Adams Street 2020 Direct Growth Equity Fund LP.
F6 The reported security is directly held by Adams Street 2021 Direct Growth Equity Fund LP.
F7 The reported security is directly held by Adams Street 2022 Direct Growth Equity Fund LP.
F8 The reported security is directly held by Adams Street Private Equity Navigator Fund LLC (f/k/a Adams Street Global Private Markets Fund LP).
F9 The reported security is directly held by Adams Street Growth Equity Fund VII LP.
F10 The reported security is directly held by FCPR GF - Lumyna Private Equity World Fund.
F11 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, may be deemed to beneficially own the shares held by Lumyna.
F12 (Continued from footnote 11) 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.
F13 Pursuant to a reclassification exempt under Rule 16b-7, each share of Common Stock was automatically reclassified into one share of Class A common stock immediately prior to the completion of the Offering.