13. Stock-Based Compensation

The Company maintains the 2021 Equity Incentive Plan (the “2021 Plan”) and the 2021 Employee Stock Purchase Plan (the “2021 ESPP”). As of September 30, 2026, 42,151,889 shares remained for future issuance under the 2021 Plan and 12,503,749 shares remained for future issuance under the 2021 ESPP. To date, the Company has issued stock options, restricted stock units and rights to purchase shares of the Company’s common stock under the 2021 ESPP only to employees, directors and consultants.

Total stock-based compensation expense was $10.1 million and $26.9 million for the three and nine months ended September 30, 2026, respectively, and was $10.7 million and $31.4 million for three and nine months ended  September 30, 2025, respectively.

Stock Options

The compensation costs for stock option awards are recognized using the straight-line attribution method over the requisite service period. Forfeitures are accounted for as they occur. Stock options vest over a four-year service period and expire on the tenth anniversary of the date of award.

The weighted-average grant date fair value of options granted during the nine months ended September 30, 2026 was $6.14. 

The Company estimated the grant date fair value of these stock options using the Black-Scholes option-pricing model with the following weighted-average assumptions:

A summary of the Company’s stock option activity during the nine months ended September 30, 2026 is as follows:

As of September 30, 2026, there was $5.4 million in unrecognized compensation costs related to all unvested options. This unrecognized stock-based compensation cost is expected to be recognized over a weighted-average period of approximately 2.8 years.

As of  September 30, 2026, the Company had 14,486,220 options outstanding and 13,457,392 options exercisable with intrinsic values of $125.3 million and $121.0 million, respectively. During the nine months ended September 30, 2026, 4,467,269 options were exercised, with a total intrinsic value of $35.1 million.

Restricted Stock Units

Under the terms of the 2021 Plan, the Company has issued restricted stock unit awards with a continuous employment condition only (“Time-Based RSUs”), and restricted stock unit awards with a continuous employment condition that are also contingent on the Company meeting certain performance goals that may be higher or lower than the granted amount (“PSUs”, and together with Time-Based RSUs, “RSUs”). Both types of RSU awards vest over periods determined at the time of grant either ratably or along a cliff vesting.

The compensation costs for RSUs are recognized using the straight-line attribution method over the requisite service period. Forfeitures are accounted for as they occur. RSUs are measured at the fair market value of the underlying stock at the grant date.

A summary of the Company’s RSU activity during the nine months ended September 30, 2026 is as follows:

RSUs that vested during the nine months ended  September 30, 2026 had an aggregate fair value at vesting of $35.1 million. As of September 30, 2026, there was $77.1 million in unrecognized compensation costs specific to the unvested RSUs, to be recognized over a weighted-average period of 2.7 years.

Employee Stock Purchase Plan

In May 2021, the Company’s Board of Directors approved the terms of the Company’s offerings under the 2021 ESPP, of which enrollment was made available to the Company’s eligible employees beginning in June 2026. Under the terms of the 2021 ESPP, eligible employees may enroll in a six-month offering period that begins in January and July of each year. Employees can elect to have up to 15% of their annual base salary, up to a maximum of $25,000 per year, withheld to purchase shares of the Company’s common stock for a purchase price equal to 85% of the lesser of the closing fair market value per share of the Company’s common stock on (i) the commencement date of the six-month offering period, or (ii) the respective purchase date. The expense that is associated with the 2021 ESPP is recorded to stock-based compensation expense and is immaterial for the nine months ended September 30, 2026. No shares of the Company’s common stock have been issued under the 2021 ESPP prior to September 30, 2026.