Company: BLLN
Filing Date: 2025-10-07
Form Type: S-1
Source: 0001193125-25-233697
Chunk: 336

Company: BillionToOne, Inc.
Filing Date: 2025-10-07
Form: S-1
Chunk 336
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 to the registration statement. Each of these statements is qualified in all respects by this reference.

Upon the completion of
this offering, we will be subject to the information reporting requirements of the Exchange Act, and we will file reports, proxy statements, and other information with the SEC. The SEC maintains a website that contains reports, proxy and information
statements, and other information regarding registrants that file electronically with the SEC. The address of the website is www.sec.gov. We also maintain a website at https://billiontoone.com, at which you may access these materials free of charge
as soon as reasonably practicable after they are electronically filed with, or furnished to, the SEC. However, the information contained in or accessible through our website is not part of this prospectus or the registration statement of which this
prospectus forms a part.

251

Index to financial statements

| BILLIONTOONE, INC. AUDITED FINANCIAL STATEMENTS AS OF AND FOR THE YEARS ENDED DECEMBER 31,   
 2024 AND 2023                                                                                |     |      |
|:---------------------------------------------------------------------------------------------|:----|:-----|
| Report of Independent Registered Public Accounting Firm                                      |     | F-2  |
| Balance Sheets                                                                               |     | F-3  |
| Statements of Operations and Comprehensive Loss                                              |     | F-4  |
| Statements of Redeemable Convertible Preferred Stock and Stockholders’                       
 Deficit                                                                                      |     | F-5  |
| Statements of Cash Flows                                                                     |     | F-6  |
| Notes to Financial Statements                                                                |     | F-8  |
| BILLIONTOONE, INC. UNAUDITED INTERIM FINANCIAL STATEMENTS AS OF AND FOR THE SIX MONTHS ENDED 
 JUNE 30, 2025 AND 2024                                                                       |     |      |
| Balance Sheets                                                                               |     | F-39 |
| Statements of Operations and Comprehensive Loss                                              |     | F-40 |
| Statements of Redeemable Convertible Preferred Stock and Stockholders’                       
 Deficit                                                                                      |     | F-41 |
| Statements of Cash Flows                                                                     |     | F-42 |
| Notes to Financial Statements                                                                |     | F-44 |

F-1

Report of Independent Registered Public Accounting Firm

To theBoard of Directors and Stockholders of BillionToOne, Inc.

Opinion on the Financial Statements

We have audited the
accompanying 2024 financial statements of BillionToOne, Inc