Company: BLLN
Filing Date: 2025-11-06
Form Type: S-8
Source: 0001193125-25-268580
Chunk: 1

Company: BillionToOne, Inc.
Filing Date: 2025-11-06
Form: S-8
Chunk 1
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 if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☐

PART I Information Required in the Section 10(a) Prospectus The information specified in this Part I is omitted from this Registration Statement on Form S-8or (the “Registration Statement”) in accordance with the provisions of Rule 428 under the Securities Act of 1933, as amended (the “Securities Act”). In accordance with the rules and regulations of the Securities and Exchange Commission (the “SEC”), and the instructions to Form S-8,such documents are not being filed with the SEC either as part of this Registration Statement or as prospectuses or prospectus supplements pursuant to Rule 424 under the Securities Act. PART II Information Required in the Registration Statement

| Item 3. | Incorporation of Documents by Reference |

BillionToOne, Inc. (the “Registrant”), hereby incorporates by reference into this Registration Statement the following documents previously filed with the SEC:

| (a) | Amendment No.                                                                                                                                                                                                              
 1 to the Registrant’s Registration Statement on Form S-1, as amended (File No. 333-290761), which contains audited financial statements for the Registrant’s latest fiscal year for which such statements have been filed; |

| (b) | the Registrant’s prospectus to be filed with the SEC on or about November 6, 2025 pursuant to Rule                         
 424(b) under the Securities Act, relating to the Registration Statement on Form S-1, as amended (File No. 333-290761); and |

| (c) | the description of the Registrant’s Class A common stock contained in the Registrant’s                                                                                                                     
 Registration Statement on Form 8-A (File No. 001- 42934),                                                                                                                                                  
 filed with the SEC on November 3, 2025 under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), including any amendments or reports filed for the purpose of updating such description. |

All other reports and documents filed by the Registrant pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act, subsequent to the filing of this Registration Statement and prior to the filing of a post-effective amendment which indicates that all securities offered hereby have been sold or which de-registersall securities then remaining unsold shall be deemed