Company: BLLN
Filing Date: 2025-09-17
Form Type: DRS/A
Source: 0001193125-25-206347
Chunk: 275

Company: BillionToOne, Inc.
Filing Date: 2025-09-17
Form: DRS/A
Chunk 275
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 • |     | our merger or consolidation after which our voting securities represent 50% or less of the total voting power of the 
 surviving or acquiring entity.                                                                                       |

Changes in capitalization In the event of certain changes in our capital structure without our receipt of consideration, such as a stock split, reverse stock split or dividend paid in Class A common stock, proportionate adjustments will automatically be made to:

| • |     | the maximum number and kind of shares available for issuance under our 2025 Plan, including the maximum number and kind of 
 shares that may be issued upon the exercise of incentive stock options;                                                    |

| • |     | the maximum number and kind of shares covered by, and exercise price, base price or purchase price, if any, applicable to 
 each outstanding stock award; and                                                                                         |

| • |     | the maximum number and kind of shares by which the share reserve may increase automatically each year. |

In the event that there is a declaration of an extraordinary dividend payable in a form other than our Class A common stock in an amount that has a material effect on the price of our Class A common stock, a recapitalization, a spin-offor a similar occurrence, the compensation committee may make such adjustments to any of the foregoing as it deems appropriate, in its sole discretion. 204

Amendments or termination

Our Board of Directors may amend, suspend or terminate our 2025 Plan at any time. If our Board of Directors amends our 2025 Plan, it does not need stockholder approval
of the amendment unless required by applicable law, regulation or rules. Our 2025 Plan will terminate automatically 10 years after the later of the date when our Board of Directors adopted our 2025 Plan or approved the latest share increase that was
also approved by our stockholders.

2018 stock plan

Our Board of
Directors adopted and our stockholders approved our 2018 Plan in December 2018. After completion of this offering, no further awards will be made under the 2018 Plan and the outstanding awards will continue to be governed by their existing terms,
except that our Class A common stock will be the class of stock underlying the outstanding awards. In addition, we will make adjustments to the number of shares and the exercise price per share underlying outstanding awards to reflect changes
made to our capital structure in connection with this offering. This summary, however, is not intended to be a complete description of the 2018 Plan and is qualified in its