Stock-Based Compensation
2020 Equity Incentive Plan
The Company’s 2020 Equity Incentive Plan (the “2020 Plan”) provides for the grant of incentive stock options, non-qualified options, stock appreciation rights, restricted stock awards, restricted stock units and other stock-based awards. The number of shares initially reserved for issuance under the 2020 Plan was (i) 2,200,000 shares (the “share pool”), plus (ii) the number of shares of common stock available for issuance under the Company’s 2016 Stock Incentive Plan (the “2016 Plan”) as of the effective date of the 2020 Plan, plus the number of shares of common stock underlying awards under the 2016 Plan that on or after the date of adoption expire or become unexercisable without delivery of shares, are forfeited to, or repurchased for cash, are settled in cash, or otherwise become available again for grant under the 2016 Plan, in each case, in accordance with its terms (up to an aggregate of 5,078,295 shares). As of December 31, 2025, 3,486,615 shares remained available for future grant under the 2020 Plan.
The share pool will automatically increase on January 1 of each year from 2021 to 2030 by the lesser of (i) four percent of the number of shares of our common stock outstanding as of the close of business on the immediately preceding December 31 and
(ii) the number of shares determined by the board of directors on or prior to such date for such year. The number of shares reserved for issuance under the 2020 Plan was increased by 2,266,293 shares effective January 1, 2026.
The 2020 Plan is administered by the board of directors or, at the discretion of the board of directors, by a committee of the board of directors. The exercise prices, vesting and other restrictions are determined at the discretion of the board of directors, or its committee if so delegated. Stock options granted with service-based vesting conditions generally vest over four years and expire after ten years. The exercise price for stock options granted is not less than the fair value of common stock on the date of grant. The Company bases fair value of common stock on the quoted market price.
2020 Employee Stock Purchase Plan
On October 21, 2020, the Company’s board of directors adopted and its stockholders approved the 2020 Employee Stock Purchase Plan (the “ESPP”), which became effective on October 21, 2020. The aggregate number of shares of common stock available for purchase pursuant to the exercise of options under the ESPP is 360,000 shares, plus an automatic annual increase, as of January 1 of each year from 2021 to 2030, equal to the lesser of one percent of the number of shares of common stock outstanding as of the close of business on the immediately preceding December 31 and (ii) the number of shares determined by the board of directors on or prior to such date for such year (up to a maximum of 3,220,520 shares). As of December 31, 2025, 2,077,652 shares remained available for future grant under the ESPP. The number of shares reserved for issuance under the ESPP was increased by 566,573 shares effective January 1, 2026.
Eligible employees may authorize payroll deductions of up to 15% of their eligible compensation during an offering period. The purchase of shares is done at a 15% discount on the lesser of (i) the Fair Market Value of a share of Stock on the first day of the offering period and (ii) the Fair Market Value of a share of Stock on the last day of the offering period. The Company currently holds two offering periods, September 1 and March 1, respectively. For the years ended December 31, 2025 and 2024, the Company recognized a de minimis amount and $0.1 million, respectively, of expense related to the ESPP.
Stock option valuation
The fair value of stock option grants is estimated using the Black-Scholes option-pricing model. The Company currently lacks company-specific historical and implied volatility information. Therefore, it estimates its expected stock volatility based on the historical volatility of a publicly traded set of peer companies. The expected term of the Company’s stock options has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is based on the fact that the Company has never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future.
The following table presents, on a weighted average basis, the assumptions used in the Black-Scholes option-pricing model to determine the grant-date fair value of stock options granted for the years ended December 31, 2025 and 2024 which was as follows:
Year Ended December 31,
20252024
Risk-free interest rate4.3 %4.1 %
Expected volatility93.5 %89.3 %
Expected dividend yield— — 
Expected term (in years)5.86.1
The following table summarizes the Company’s option activity for the year ended December 31, 2025 which was as follows:
Number of
Options
Weighted
Average
Exercise
Price
Weighted
Average
Contractual
Term
Aggregate
Intrinsic
Value
(in years)(in thousands)
Outstanding as of December 31, 20248,989,893 $8.34 7.1$6,388 
Granted2,531,222 4.38 
Exercised(213,710)1.85 
Forfeited/Expired
(1,049,904)8.23 
Outstanding as of December 31, 202510,257,501 $7.51 6.7$9,690 
Options exercisable as of December 31, 20256,334,480 $9.00 5.5$5,556 
The aggregate intrinsic value of stock options is calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common stock for those stock options that had exercise prices lower than the fair value of the Company’s common stock. The aggregate intrinsic value of stock options exercised for the years ended December 31, 2025 and 2024 was $0.5 million and $1.8 million, respectively
The weighted average grant-date fair value of stock options granted for the years ended December 31, 2025 and 2024 was $3.32 per share and $3.14 per share, respectively.
Stock-based compensation
The Company recorded stock-based compensation expense related to common stock options in the following expense categories of its consolidated statements of operations and comprehensive loss for the years ended December 31, 2025 and 2024 which was as follows (in thousands):
Year Ended December 31,
20252024
Research and development expenses$4,336 $4,955 
General and administrative expenses6,063 6,938 
$10,399 $11,893 
As of December 31, 2025, total unrecognized compensation cost related to unvested options was $11.7 million, which is expected to be recognized over a weighted average period of 2.1 years.

Historical Timeline

Fiscal YearFiled
2025Mar 11, 2026Showing above
2024Mar 6, 2025
2023Mar 7, 2024
2022Mar 9, 2023
2020Mar 18, 2021

About Stock Compensation Disclosures

Stock-based compensation disclosures detail the equity awards granted to employees and executives — including stock options, restricted stock units (RSUs), and performance shares — along with the valuation methods and assumptions used to expense them. This section reveals the true cost of talent retention and the alignment between management incentives and shareholder interests.

Key signals: total unrecognized compensation expense and its expected recognition period signal future earnings headwinds from already-granted awards. For stock options, examine Black-Scholes assumptions — expected volatility, risk-free rate, and expected term — as understating any of these reduces reported compensation expense. Compare stock compensation expense as a percentage of revenue against peers to assess dilution cost. Watch vesting schedules for acceleration clauses tied to change-of-control events. Performance-based awards with undemanding targets may indicate weak governance. Add back stock compensation to operating cash flow to calculate a more conservative free cash flow figure.