Company: BLLN
Filing Date: 2025-08-11
Form Type: DRS/A
Source: 0000950123-25-007483
Chunk: 3

Company: BillionToOne, Inc.
Filing Date: 2025-08-11
Form: DRS/A
Chunk 3
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 the section titled “Underwriting” for a description of the compensation payable to the underwriters. |

At our request, the underwriters have reserved up to 5% of the shares of Class A common stock being offered by this prospectus for sale, at the initial public offering price, to our officers, directors and employees through a directed share program. See the section titled “Underwriting – Directed share program.” We have granted the underwriters an option for a period of 30 days to purchase up to additional shares of Class A common stock. Investing in our Class A common stock involves a high degree of risk. See “ Risk factors” beginning on page 20. Neither the Securities and Exchange Commission nor any other state securities commission has approved or disapproved of these securities or passed on the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense. The underwriters expect to deliver the shares to purchasers on or about , 2025.

| J.P. Morgan |     | Piper Sandler          |     | Jefferies |     | William Blair |
| Stifel      |     | Wells Fargo Securities |     |           |     | BTIG          |

, 2025

### EXPLANATORY NOTE
Pursuant
to the applicable provisions of the Fixing America’s Surface Transportation Act, we are omitting our unaudited financial statements as of and for the three months ended March 31, 2025 and 2024. While this financial information is otherwise
required by Regulation S-X, we reasonably believe that it will not be required to be included in the prospectus at the time of the contemplated offering. We intend to amend this registration
statement to include all financial information required by Regulation S-X at the date of such amendment before distributing a preliminary prospectus to investors.

BILLION TOONE We strive to remove the fear of the unknown. Our revolutionary technology allows us to push beyond the current limitations in diagnostics so we can detect disease one molecule at a time. We provide patients with powerful and precise information about the state of their health for themselves and their children. And it's only the beginning of what we seek to do.

Key Metrics annualized revenue run-rate (ARR)1 YOY revenue growth2 Emerging profitability3 $100B US annual market opportunity4 REVENUE LTM revenue5 167% CAGR (2021-2024) TESTS ACCESSIONED6 LTM tests accessioned as of Jun 30, 2025 YO