# EDGAR Filing Document

**Accession Number:** 0002087538
**File Stem:** 0001193125-25-274945
**Filing Date:** 2025-11
**Character Count:** 18070
**Document Hash:** 7bd51ceb62a36e6bce7829c3e65d1f7e
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-25-274945.hdr.sgml**: 20251110

**ACCESSION NUMBER**: 0001193125-25-274945

**CONFORMED SUBMISSION TYPE**: 4

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20251106

**FILED AS OF DATE**: 20251110

**DATE AS OF CHANGE**: 20251110

**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Bremner Thomas S
- **CENTRAL INDEX KEY:** 0002087538

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-42934
- **FILM NUMBER:** 251468094

**MAIL ADDRESS:**
- **STREET 1:** 1 N WACKER DR.
- **STREET 2:** #2700
- **CITY:** CHICAGO
- **STATE:** IL
- **ZIP:** 60606
**ISSUER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** BillionToOne, Inc.
- **CENTRAL INDEX KEY:** 0002070849
- **STANDARD INDUSTRIAL CLASSIFICATION:** SERVICES-MEDICAL LABORATORIES [8071]
- **ORGANIZATION NAME:** 08 Industrial Applications and Services
- **EIN:** 811082020
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**BUSINESS ADDRESS:**
- **STREET 1:** 1035 O'BRIEN DRIVE
- **CITY:** MENLO PARK
- **STATE:** CA
- **BUSINESS PHONE:** 650-460-2551

**MAIL ADDRESS:**
- **STREET 1:** 1035 O'BRIEN DRIVE
- **CITY:** MENLO PARK
- **STATE:** CA
- **ZIP:** 94025

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## FORM 4

### STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

[ ] 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**<sup>*</sup><br>Bremner Thomas S<br><sub>(Last) (First) (Middle)</sub><br>1 NORTH WACKER DRIVE, SUITE 2200<br><sub>(Street)</sub><br>CHICAGO, IL 60606-2807<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2025-11-06 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[X] Director [ ] 10% Owner<br>[ ] Officer (give title below) [ ] Other (specify below)<br>_ _ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>BillionToOne, Inc. [ BLLN ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[X] Form filed by One Reporting Person<br>[ ] Form filed by More than One Reporting Person |

---

## Table I - Non-Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | 3. Transaction Code (V) | 3. Transaction Code (V) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | Code | V | Amount | (A) or (D) | Price | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| Common Stock | 2025-11-06 |  | A |  | 8333<sup>(1)</sup> | A | $0 | 8333 | D |  |
| Common Stock | 2025-11-07 |  | C<sup>(2)(3)</sup> |  | 152440 | A | <sup>(3)</sup> | 152440 | I | See Footnotes<sup>(4)(11)(12)</sup> |
| Common Stock | 2025-11-07 |  | C<sup>(2)(3)</sup> |  | 155711 | A | <sup>(3)</sup> | 155711 | I | See Footnotes<sup>(5)(11)(12)</sup> |
| Common Stock | 2025-11-07 |  | C<sup>(2)(3)</sup> |  | 176271 | A | <sup>(3)</sup> | 176271 | I | See Footnotes<sup>(6)(11)(12)</sup> |
| Common Stock | 2025-11-07 |  | C<sup>(2)(3)</sup> |  | 269918 | A | <sup>(3)</sup> | 269918 | I | See Footnotes<sup>(7)(11)(12)</sup> |
| Common Stock | 2025-11-07 |  | C<sup>(2)(3)</sup> |  | 240072 | A | <sup>(3)</sup> | 240072 | I | See Footnotes<sup>(8)(11)(12)</sup> |
| Common Stock | 2025-11-07 |  | C<sup>(2)(3)</sup> |  | 675352 | A | <sup>(3)</sup> | 675352 | I | See Footnotes<sup>(9)(11)(12)</sup> |
| Common Stock | 2025-11-07 |  | C<sup>(2)(3)</sup> |  | 277508 | A | <sup>(3)</sup> | 277508 | I | See Footnotes<sup>(10)(11)(12)</sup> |
| Common Stock | 2025-11-07 |  | J<sup>(13)</sup> |  | 8333 | D | <sup>(13)</sup> | 0 | D |  |
| Common Stock | 2025-11-07 |  | J<sup>(13)</sup> |  | 152440 | D | <sup>(13)</sup> | 0 | I | See Footnotes<sup>(4)(11)(12)</sup> |
| Common Stock | 2025-11-07 |  | J<sup>(13)</sup> |  | 155711 | D | <sup>(13)</sup> | 0 | I | See Footnotes<sup>(5)(11)(12)</sup> |
| Common Stock | 2025-11-07 |  | J<sup>(13)</sup> |  | 176271 | D | <sup>(13)</sup> | 0 | I | See Footnotes<sup>(6)(11)(12)</sup> |
| Common Stock | 2025-11-07 |  | J<sup>(13)</sup> |  | 269918 | D | <sup>(13)</sup> | 0 | I | See Footnotes<sup>(7)(11)(12)</sup> |
| Common Stock | 2025-11-07 |  | J<sup>(13)</sup> |  | 240072 | D | <sup>(13)</sup> | 0 | I | See Footnotes<sup>(8)(11)(12)</sup> |
| Common Stock | 2025-11-07 |  | J<sup>(13)</sup> |  | 675352 | D | <sup>(13)</sup> | 0 | I | See Footnotes<sup>(9)(11)(12)</sup> |
| Common Stock | 2025-11-07 |  | J<sup>(13)</sup> |  | 277508 | D | <sup>(13)</sup> | 0 | I | See Footnotes<sup>(10)(11)(12)</sup> |
| Class A Common Stock | 2025-11-07 |  | J<sup>(13)</sup> |  | 8333 | A | <sup>(13)</sup> | 8333 | D |  |
| Class A Common Stock | 2025-11-07 |  | J<sup>(13)</sup> |  | 152440 | A | <sup>(13)</sup> | 152440 | I | See Footnotes<sup>(4)(11)(12)</sup> |
| Class A Common Stock | 2025-11-07 |  | J<sup>(13)</sup> |  | 155711 | A | <sup>(13)</sup> | 155711 | I | See Footnotes<sup>(5)(11)(12)</sup> |
| Class A Common Stock | 2025-11-07 |  | J<sup>(13)</sup> |  | 176271 | A | <sup>(13)</sup> | 176271 | I | See Footnotes<sup>(6)(11)(12)</sup> |
| Class A Common Stock | 2025-11-07 |  | J<sup>(13)</sup> |  | 269918 | A | <sup>(13)</sup> | 269918 | I | See Footnotes<sup>(7)(11)(12)</sup> |
| Class A Common Stock | 2025-11-07 |  | J<sup>(13)</sup> |  | 240072 | A | <sup>(13)</sup> | 240072 | I | See Footnotes<sup>(8)(11)(12)</sup> |
| Class A Common Stock | 2025-11-07 |  | J<sup>(13)</sup> |  | 675352 | A | <sup>(13)</sup> | 675352 | I | See Footnotes<sup>(9)(11)(12)</sup> |
| Class A Common Stock | 2025-11-07 |  | J<sup>(13)</sup> |  | 277508 | A | <sup>(13)</sup> | 277508 | I | See Footnotes<sup>(10)(11)(12)</sup> |
| Class A Common Stock | 2025-11-07 |  | P |  | 4016 | A | $60 | 156456 | I | See Footnotes<sup>(4)(11)(12)</sup> |
| Class A Common Stock | 2025-11-07 |  | P |  | 4084 | A | $60 | 159795 | I | See Footnotes<sup>(5)(11)(12)</sup> |
| Class A Common Stock | 2025-11-07 |  | P |  | 3462 | A | $60 | 179733 | I | See Footnotes<sup>(6)(11)(12)</sup> |
| Class A Common Stock | 2025-11-07 |  | P |  | 5446 | A | $60 | 275364 | I | See Footnotes<sup>(7)(11)(12)</sup> |
| Class A Common Stock | 2025-11-07 |  | P |  | 6867 | A | $60 | 246939 | I | See Footnotes<sup>(8)(11)(12)</sup> |
| Class A Common Stock | 2025-11-07 |  | P |  | 17791 | A | $60 | 693143 | I | See Footnotes<sup>(9)(11)(12)</sup> |

---

## Table II - Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | 4. Transaction Code (V) | 4. Transaction Code (V) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 6. Date Exercisable and Expiration Date | 6. Date Exercisable and Expiration Date | 7. Title and Amount of Underlying Securities | 7. Title and Amount of Underlying Securities | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | Code | V | (A) | (D) | Date Exercisable | Expiration Date | Title | Amount or Number of Shares | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
| Series A-1 Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 1352 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 1352 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(4)(11)(12)</sup> |
| Series C Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 114117 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 114117 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(4)(11)(12)</sup> |
| Series C-1 Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 16747 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 16747 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(4)(11)(12)</sup> |
| Series D Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 20224 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 20224 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(4)(11)(12)</sup> |
| Series C Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 121688 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 121688 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(5)(11)(12)</sup> |
| Series C-1 Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 17858 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 17858 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(5)(11)(12)</sup> |
| Series D Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 16165 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 16165 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(5)(11)(12)</sup> |
| Series A-1 Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 1562 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 1562 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(6)(11)(12)</sup> |
| Series C Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 131888 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 131888 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(6)(11)(12)</sup> |
| Series C-1 Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 19355 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 19355 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(6)(11)(12)</sup> |
| Series D Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 23466 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 23466 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(6)(11)(12)</sup> |
| Series A-1 Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 1864 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 1864 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(7)(11)(12)</sup> |
| Series C Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 157404 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 157404 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(7)(11)(12)</sup> |
| Series C-1 Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 23100 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 23100 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(7)(11)(12)</sup> |
| Series D Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 87550 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 87550 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(7)(11)(12)</sup> |
| Series A-1 Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 652 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 652 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(8)(11)(12)</sup> |
| Series C Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 55091 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 55091 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(8)(11)(12)</sup> |
| Series C-1 Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 8084 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 8084 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(8)(11)(12)</sup> |
| Series D Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 176245 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 176245 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(8)(11)(12)</sup> |
| Series A-1 Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 5988 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 5988 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(9)(11)(12)</sup> |
| Series C Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 505570 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 505570 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(9)(11)(12)</sup> |
| Series C-1 Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 74195 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 74195 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(9)(11)(12)</sup> |
| Series D Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 89599 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 89599 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(9)(11)(12)</sup> |
| Series A-1 Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 1078 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 1078 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(10)(11)(12)</sup> |
| Series C Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 91003 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 91003 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(10)(11)(12)</sup> |
| Series C-1 Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 13355 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 13355 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(10)(11)(12)</sup> |
| Series D Convertible Preferred Stock | <sup>(3)</sup> | 2025-11-07 |  | C |  |  | 122072 | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 122072 | <sup>(3)</sup> | 0 | I | See Footnotes<sup>(10)(11)(12)</sup> |

---

### Footnotes:

(1) 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.

(2) 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.

(3) 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.

(4) The reported security is directly held by Adams Street 2019 Direct Growth Equity Fund LP.

(5) The reported security is directly held by Adams Street 2020 Direct Growth Equity Fund LP.

(6) The reported security is directly held by Adams Street 2021 Direct Growth Equity Fund LP.

(7) The reported security is directly held by Adams Street 2022 Direct Growth Equity Fund LP.

(8) The reported security is directly held by Adams Street Private Equity Navigator Fund LLC (f/k/a Adams Street Global Private Markets Fund LP).

(9) The reported security is directly held by Adams Street Growth Equity Fund VII LP.

(10) The reported security is directly held by FCPR GF - Lumyna Private Equity World Fund.

(11) 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.

(12) (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.

(13) 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.

**Signature:** /s/ Thomas P. Lynch, Attorney-in-Fact  
**Date:** 2025-11-10

### Remarks:

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.**