Company: BLLN
Filing Date: 2025-10-17
Form Type: S-1/A
Source: 0001193125-25-242632
Chunk: 294

Company: BillionToOne, Inc.
Filing Date: 2025-10-17
Form: S-1/A
Chunk 294
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 in this offering, for:

| • |     | each person, or group of affiliated persons, who is known by us to beneficially own more than 5% of our common stock; |

| • |     | each of our named executive officers; |

| • |     | each of our directors; and |

| • |     | all of our current executive officers and directors as a group. |

We have determined beneficial ownership in accordance with the rules of the SEC. These rules generally attribute beneficial ownership of securities to persons who possess sole or shared voting or investment power with respect to those securities. The information contained in the following table is not necessarily indicative of beneficial ownership for any other purpose, and the inclusion of any shares in the table does not constitute an admission of beneficial ownership of those shares. Unless otherwise indicated by the footnotes below, we believe, based on the information furnished to us, that the persons or entities identified in this table have sole voting and investment power with respect to all shares shown as beneficially owned by them, subject to applicable community property laws. The percentage ownership information shown in the table prior to this offering is based upon 35,710,052 shares of Class A common stock and 4,552,650 shares of Class B common stock outstanding as of September 30, 2025, assuming (i) the Preferred Stock Conversion, (ii) the Reclassification, and (iii) the Class B Stock Exchange. The percentage ownership information shown in the table after this offering is based upon 39,556,052 shares of Class A common stock and 4,552,650 shares of Class B common stock outstanding immediately after the closing of the offering, assuming no exercise of the underwriters’ option to purchase additional shares of Class A common stock. We have deemed shares of our Class A common stock subject to stock options that are currently exercisable or exercisable within 60 days of September 30, 2025 to be outstanding and to be beneficially owned by the person holding the stock option for the purpose of computing the percentage ownership of that person. We did not deem these shares outstanding, however, for the purpose of computing the percentage ownership of any other person. In addition, the table below excludes any potential purchases in this offering by the beneficial owners identified in the table below, including in the directed share program. Except as otherwise noted below, the address for persons listed in the table is c/o BillionToOne, Inc., 1035 O’Brien Drive, Menlo Park, CA