Company: BLLN
Filing Date: 2025-10-17
Form Type: S-1/A
Source: 0001193125-25-242632
Chunk: 278

Company: BillionToOne, Inc.
Filing Date: 2025-10-17
Form: S-1/A
Chunk 278
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 will be eligible to receive the following benefits, provided the Participant signs a release of claims:

| • |     | Continuation of the Participant’s base salary for a period of (i) in the case of Tier 1 Participants, 12 months, (ii) 
 in the case of Tier 2 Participants, 9 months, or, (iii) in the case of a Tier 3 Participant, 6 months.                |

| • |     | Continuation of the Participant’s health and welfare benefits for the shorter of (i) in the case of Tier 1                                                                                                                                         
 Participants, 12 months, in the case of Tier 2 Participants, 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