Company: BLLN
Filing Date: 2025-08-11
Form Type: DRS/A
Source: 0000950123-25-007483
Chunk: 253

Company: BillionToOne, Inc.
Filing Date: 2025-08-11
Form: DRS/A
Chunk 253
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ments beginning with October 6, 2024, subject to the named executive officer’s continued service to the Company through the applicable vesting 
 date.                                                                                                                                                                                                          |

195

| (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 Pursuant to their employment letter agreements, which will become effective upon the completion of this offering, we expect that each of Dr. Atay, Mr. Taylor and Ms. Johnson will be eligible to participate in our Executive Severance and Change in Control Plan. Pursuant to the Executive Severance and Change in Control Plan, we expect that each of our named executive officers will be eligible to receive the following severance benefits in the event that their employment is terminated by us without Cause (as defined below) or if they resign for Good Reason (as defined below) (either of which, a Qualifying Termination):

| • |     | An amount equal to    months of base salary; |

| • |     | Reimbursement for continued benefit coverage pursuant to COBRA, equal in length for up to the number of months of the 
 officer’s severance benefit; and                                                                                      |

| • |     | If such termination is    months prior to or within    months after a                       
 change in control then the vesting of all then-unvested option shares shall be accelerated. |

Equity plans 2025 equity incentive plan Our Board of Directors intends to adopt and approve our 2025 Equity Incentive Plan (the 2025 Plan), prior to this offering and it will be submitted to our stockholders for approval. We expect that the 2025 Plan 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 Plan will continue to be governed by their existing terms. It is expected that our 2025