Company: BLLN
Filing Date: 2025-08-11
Form Type: DRS/A
Source: 0000950123-25-007483
Chunk: 346

Company: BillionToOne, Inc.
Filing Date: 2025-08-11
Form: DRS/A
Chunk 346
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 the original exercise price in the event that the optionee’s service is terminated for any reason. If an option does not permit early exercise, then such option shall not be exercisable with respect to unvested shares. As of December 31, 2024, the Company had authorized 10,904,372 shares of common stock reserved for issuance under the 2018 Plan. Stock-based Compensation The Company recognizes stock-based compensation expense for all stock-based payment awards based on the estimated fair value on the date of the grant. The Company recognizes the compensation cost on a straight-line basis over the requisite service period of the award. The fair value of stock options granted is estimated using the Black-Scholes Model utilizing the assumptions noted below:

| • |     | Fair value of common stock. The Board of Directors considers numerous objective and subjective factors to                                                                                                                                     
 determine the fair value of the Company’s common stock options at each meeting in which awards are approved. The factors considered include, but are not limited to: (i) the results of contemporaneous independent third party valuations of 
 the Company’s common stock; (ii) the prices, rights, preferences and privileges of the Company’s redeemable convertible preferred stock relative to those of its common stock; (iii) the lack of marketability of the Company’s               
 common stock; (iv) actual operating and financial results; (v) current business conditions and projections; and (vi) the likelihood of achieving a liquidity event, such as an initial public offering or sale of the Company, given          
 prevailing market conditions.                                                                                                                                                                                                                 |

| • |     | Expected volatility. Expected volatility is a measure of the amount by which the stock price is expected                                                                                                                                                  
 to fluctuate. Since the Company does not have sufficient trading history of its common stock, it estimates the expected volatility of its stock options at their grant date by taking the weighted average historical volatility of a group of comparable 
 publicly traded companies over a period equal to the expected life of the options.                                                                                                                                                                        |

| • |     | Expected term. Expected term represents the period over which the Company anticipates stock-based awards                                                                                                                                  
 to be outstanding. The Company uses the simplified method to calculate the expected term estimate based on the options’ vesting term and contractual terms. Under the simplified method, the expected life is equal to the average of the 
 stock-based award’s weighted average vesting period and its contractual term.                                                                                                                                                             |

| • |     | Risk-free interest rate. The Company uses the average of the published interest rates