Company: BLLN
Filing Date: 2025-10-07
Form Type: S-1
Source: 0001193125-25-233697
Chunk: 370

Company: BillionToOne, Inc.
Filing Date: 2025-10-07
Form: S-1
Chunk 370
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 Plan (the “2018 Plan”). The 2018 Plan authorizes the granting of stock options upon the approval of the Company’s Board of Directors, to employees and consultants providing services to the Company. Stock options granted under the 2018 Plan generally expire within 10 years from the date of grant and are generally issued at the fair value of the underlying shares of common stock on the date of grant as determined by the Company’s Board of Directors. The shares subject to each option typically allow for 25% of the shares to vest and become exercisable on the first anniversary of the vesting commencement date and thereafter, the remaining 75% will vest and become exercisable in 36 equal monthly installments. The Company may include other vesting terms from time to time. Incentive and non-statutorystock options may be granted with exercise prices not less than 100% of the estimated fair value of the common stock on the date of grant, as determined by the Board of Directors. Subject to Board approval at the grant date, if an option includes an “early exercise” feature, then such option shall be exercisable at any time but any unvested option shares shall be subject to the Company’s right to repurchase them at 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 market