Company: BLLN
Filing Date: 2025-08-11
Form Type: DRS/A
Source: 0000950123-25-007483
Chunk: 256

Company: BillionToOne, Inc.
Filing Date: 2025-08-11
Form: DRS/A
Chunk 256
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 for a payment equal to the excess, if any, of the value that the holder of each share of our Class A common stock receives in the transaction over (if applicable) the exercise price otherwise payable in connection with 
 the award; or                                                                                                                                                                                                                                       |

| • |     | the assignment of any reacquisition or repurchase rights held by us in respect of an award of restricted shares to the               
 surviving entity or its parent (with proportionate adjustments made to the price per share to be paid upon exercise of such rights). |

The compensation committee is not required to treat all awards, or portions thereof, in the same manner. The vesting of an outstanding award may be accelerated by the administrator upon the occurrence of a change in control, whether or not the award is to be assumed or replaced in the transaction, or in connection with a termination of service following a change in control transaction. A change in control includes:

| • |     | any person acquiring beneficial ownership of more than 50% of our total voting power; |

| • |     | the sale or other disposition of all or substantially all of our assets; or |

| • |     | 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. 198

Amendments or termination

Our Board of Directors