Company: BLLN
Filing Date: 2025-10-07
Form Type: S-1
Source: 0001193125-25-233697
Chunk: 273

Company: BillionToOne, Inc.
Filing Date: 2025-10-07
Form: S-1
Chunk 273
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 9 months, or, in the case of a Tier 3 Participant, 6 months, (ii) until the date of the Participant’s eligibility for health insurance coverage in connection with new employment, or 
 (iii) the expiration of the Participant’s eligibility for the continuation coverage under COBRA.                                                                                                                                                   |

Termination in Connection with a Change in Control Termination.In the event of an Involuntary Termination (or, in the case of a Tier 3 Participant, a Termination Without Cause) that occurs within 12 months following a Change in Control, a Participant will be eligible to receive the following benefits, as applicable, provided the Participant signs a release of claims:

| • |     | A lump sum cash payment equal to a percentage multiplied by the sum of (i) the Participant’s annual base salary and                                                                                         
 (ii) the Participant’s annual target bonus, with such percentage equal to 150%, in the case of a Tier 1 Participant, 100% in the case of a Tier 2 Participant, and 75% in the case of a Tier 3 participant. |

| • |     | With respect to time-based equity awards, full vesting of any outstanding and then-unvested time-based equity awards held 
 by the Participant.                                                                                                       |

| • |     | With respect to performance-based equity awards, if any, such performance-based awards held by the Participant shall vest 
 based on the terms of the applicable award agreement for the performance-based award.                                     |

| • |     | A lump sum cash payment equal to the product of (i) the employer’s portion of the Participant’s monthly COBRA                                                      
 premiums and (ii) in the case of a Tier 1 Participant, 18 months, in the case of a Tier 2 Participant, 12 months, or, in the case of Tier 3 Participant, 9 months. |

The terms “Change in Control,” “Involuntary Termination,” and “Termination Without Cause” shall have the meanings ascribed to such terms in the Severance Plan. Equity plans 2025 equity incentive plan Our 2025 plan was adopted by our Board of Directors on October 7, 2025, will be submitted to our stockholders for approval prior to this offering, and will become effective upon the effectiveness of the registration statement of which this prospectus is a part. Our 2025 Plan is intended to replace our 2018 Plan. However, awards outstanding under the 2018