Company: BLLN
Filing Date: 2025-10-17
Form Type: S-1/A
Source: 0001193125-25-242632
Chunk: 277

Company: BillionToOne, Inc.
Filing Date: 2025-10-17
Form: S-1/A
Chunk 277
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-year anniversary of January 8, 2024, and vests and becomes exercisable with respect to 1/48th of the shares in equal monthly installments thereafter, subject to the named executive officer’s continued service to the Company through the applicable vesting date. |

| (2) |     | Option vests and becomes exercisable in 48 equal monthly installments beginning with October 6, 2024, subject to the named executive officer’s continued service to the Company through the applicable vesting 
 date.                                                                                                                                                                                                          |

| (3) |     | Option vests and becomes exercisable in 48 equal monthly installments beginning with October 1, 2023, subject to the named executive officer’s continued service to the Company through the applicable vesting 
 date.                                                                                                                                                                                                          |

| (4) |     | Option vests and becomes exercisable in 48 equal monthly installments beginning with September 1, 2021, subject to the named executive officer’s continued service to the Company through the applicable vesting 
 date.                                                                                                                                                                                                            |

Severance and change in control benefits Our Board of Directors has approved the BillionToOne, Inc. Executive Severance Plan (the Severance Plan) prior to this offering to offer severance benefits to our named executive officers and to certain other key executives and employees (each, a Participant). The compensation committee of the Board has the authority to designate the executives and key employees who will be offered an opportunity to participate in the Severance Plan and will administer the Severance Plan. To participate in the Severance Plan, the Participant must enter into a Participation Agreement (each a, Participation Agreement), which provides that the terms and conditions of the Severance Plan shall supersede and replace any rights to severance and change in control benefits under any existing employment or severance agreement between us and the Participant. Each of Dr. Atay, Mr. Taylor and Ms. Johnson will be eligible to participate in our Severance Plan pursuant to which Dr. Atay will be a Tier 1 Participant, and each of Mr. Taylor and Ms. Johnson will be Tier 2 Participants. Tier 1, Tier 2, and Tier 3 Participants are entitled to the following severance benefits, as applicable: Termination that Does Not Qualify as 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 is not a Change in Control 205

Termination, a Participant