Stock-Based Compensation | 9. Stock-Based Compensation Equity Incentive Award Plans In March 2021, the Company’s board of directors and stockholders adopted the 2021 Plan, which became effective on March 25, 2021, the date of the underwriting agreement related to the Company’s IPO. Upon adoption of the 2021 Plan, the Company restricted future grants from its 2018 Plan. Under the 2021 Plan, the Company may grant stock options, stock appreciation rights, restricted stock, restricted stock units, performance stock awards, performance cash awards and other forms of stock awards to employees, directors and consultants, including employees and consultants of the Company’s affiliates. As of December 31, 2022, the Company had 5,914,999 shares available for grant under the 2021 Plan. In addition, the number of shares of common stock available for issuance under the 2021 Plan will automatically increase on January 1 of each calendar year, starting on January 1, 2022 through January 1, 2031, in an amount equal to 5% of the total number of shares outstanding of the Company’s common stock on the last day of the calendar month before the date of each automatic increase, or a lesser number of shares determined by the Company’s board of directors. Effective January 1, 2023, the number of shares available for future issuance was increased by 2,797,165 shares so that the total available for future issuance as of January 1, 2023 was 8,712,164 shares. A summary of the Company's stock option activity for the periods presented was as follows (in thousands, except year, share and per share data): Weighted- Average Number of Weighted- Remaining Options and Average Contractual Aggregate Awards Exercise Term Intrinsic Outstanding Price (Years) Value Outstanding at December 31, 2020 1,601,214 $ 0.91 9.71 $ 8,468 Granted 1,439,444 $ 15.60 Exercised ( 52,974 ) $ 0.65 Canceled ( 313,909 ) $ 3.82 Outstanding at December 31, 2021 2,673,775 $ 8.49 9.12 35,343 Granted 3,132,283 $ 13.50 Exercised ( 226,128 ) $ 1.43 Canceled/Expired ( 183,211 ) $ 9.81 Outstanding at December 31, 2022 5,396,719 $ 11.64 8.75 $ 10,533,451 Vested and expected to vest at December 31, 2022 5,396,719 $ 11.64 8.75 $ 10,533,451 Exercisable at December 31, 2022 1,417,736 $ 7.22 8.07 $ 8,075,544 The weighted-average grant date fair value per share of options granted was $ 8.63 and $ 12.39 for the years ended December 31, 2022 and 2021, respectively. The aggregate intrinsic value of options exercised was $ 4.0 million and $ 0.8 million for the years ended December 31, 2022 and 2021, respectively, and the cash received from options exercised was $ 0.3 million and less than $ 0.1 million for the years ended December 31, 2022 and 2021. The weighted-average assumptions used in the Black-Scholes option pricing model to determine the fair value of stock option grants for the periods presented were as follows: Year Ended 2022 2021 Fair value of common stock 13.50 15.60 Expected term (years) 6.10 6.07 Expected volatility 70.40 % 72.83 % Risk-free interest rate 2.01 % 1.04 % Expected dividend yield 0.0 % 0.0 % The Company determines the assumptions used in the option pricing model in the following manner: Fair Value of Common Stock —The grant date fair market value of the shares of common stock underlying stock options is determined by the Company’s board of directors. Following the closing of the Company’s IPO, the fair market value of our common stock is based on its closing price as reported on the date of grant on the primary stock exchange on which the Company’s common stock is traded. Prior to the Company’s IPO, because there was no public market for the Company’s common stock, the board of directors considered, among other things, input from management and valuations of the Company's stock prepared by unrelated third-party valuation firms. Expected Term —The expected term of stock options represents the period of time that the awards are expected to be outstanding. Because the Company does not have sufficient historical exercise behavior, it determines the expected term assumption using the simplified method for employees and board members, which calculates the expected term as the average time-to-vesting and the contractual life of the award. The expected term for non-employees is generally the contractual term. Expected Volatility —Given the Company's limited historical stock price volatility data, the expected volatility assumption was determined by examining the historical volatilities of a group of industry peers whose share prices are publicly available. Risk-Free Interest Rate —The risk-free rate assumption is based on the U.S. Treasury yield in effect at the time of the grant with maturities consistent with the expected term of the awards. Expected Dividend Yield —The expected dividend yield assumption is based on the Company’s history and expectation of dividend payouts. The Company has not paid and does not intend to pay dividends and, therefore, used an expected dividend yield of zero . 2021 Employee Stock Purchase Plan In March 2021, the Company’s board of directors and stockholders adopted the ESPP, which became effective on March 25, 2021, the date of the underwriting agreement related to the Company’s IPO. The ESPP permits eligible employees who elect to participate in an offering under the ESPP to have up to 15 % of their eligible earnings withheld, subject to certain limitations, to purchase shares of common stock pursuant to the ESPP. The price of common stock purchased under the ESPP is equal to 85 % of the lower of the fair market value of the common stock at the commencement date of each offering period or the relevant date of purchase. A total of 600,000 shares of common stock were approved to be initially reserved for issuance under the ESPP. In addition, the number of shares of common stock available for issuance under the ESPP will automatically increase on January 1 of each calendar year, starting on January 1, 2022 through January 1, 2031, in an amount equal to the lesser of (i) 1% of the total number of shares outstanding of the Company’s common stock on the last day of the calendar month before the date of each automatic increase and (ii) 1,200,000 shares; provided that before the date of any such increase, the Company’s board of directors may determine that such increase will be less than the amount set forth in clauses (i) and (ii). Effective January 1, 2023, the number of shares available for issuance was increased by 559,433 shares so that the total available for future issuance as of January 1, 2023 was 1,669,360 shares. As of December 31, 2022, the Company had issued 46,890 shares of the Company's common stock under the ESPP and had 1,109,927 shares available for future issuance. In determining the grant date fair value of shares to be issued under the ESPP, the Company uses the Black-Scholes option pricing model. The Black-Scholes inputs are determined in the same manner as for stock option awards. The weighted average inputs used for the ESPP for the year ended December 31, 2022, were as follows: Year Ended 2022 2021 Fair value of common stock 12.51 19.96 Expected term (years) 1.26 1.41 Expected volatility 78.01 % 69.26 % Risk-free interest rate 2.78 % 0.18 % Expected dividend yield 0.0 % 0.0 % Stock-based compensation expense for all equity awards has been reported in the statements of operations and comprehensive loss as follows (in thousands): Year Ended 2022 2021 Research and development $ 4,827 $ 1,827 General and administrative 6,098 2,862 Total $ 10,925 $ 4,689 As of December 31, 2022, unrecognized compensation expense related to unvested stock option awards was $ 33.2 million, which is expected to be recognized in expense over a weighted-average period of 2.8 years. As of December 31, 2022, unrecognized compensation expense related to ESPP rights was $ 0.4 million, which is expected to be recognized over a remaining period of 1.6 years. |