Stock-Based Compensation | 11. Stock-based compensation 2020 Stock incentive plan The Company’s 2020 Stock Option and Grant Plan, or the 2020 Plan, provided for the Company to grant stock options, restricted stock and other stock awards, to employees, non-employee directors, and consultants. Upon the effectiveness of the 2021 Plan (as defined below), no further issuances were made under the 2020 Plan. 2021 Stock incentive plan The Company’s 2021 Stock Option and Incentive Plan, or the 2021 Plan, was approved by the Company’s board of directors on May 28, 2021 and the Company’s stockholders on June 17, 2021 and became effective on the date immediately prior to the date on which the registration statement for the Company’s IPO was declared effective. The 2021 Plan provides for the grant of incentive stock options, non-qualified stock options, stock appreciation rights, restricted stock units, restricted stock awards, unrestricted stock awards, cash-based awards and dividend equivalent rights to the Company’s officers, employees, directors and consultants. The number of shares initially reserved for issuance under the 2021 Plan was 4,903,145 . Under the evergreen provision of the 2021 Plan, the shares available for issuance under the 2021 Plan will be automatically increased each January 1st by 5 % of the outstanding number of shares of the Company’s common stock on the immediately preceding December 31st or such lesser number of shares as may be determined by the Company’s compensation, nomination and corporate governance committee. Effective January 1, 2024 the number of shares available under the 2021 Plan automatically increased by 2,507,011 shares pursuant to the evergreen provision of the 2021 Plan. As of June 30, 2024, 3,359,639 shares were available for issuance under the 2021 Plan. 2021 Employee stock purchase plan The Company’s 2021 Employee Stock Purchase Plan, or the 2021 ESPP, was approved by the Company’s board of directors on May 28, 2021 and the Company’s stockholders on June 17, 2021 and became effective on the date immediately prior to the date on which the registration statement for the Company’s IPO was declared effective. A total of 439,849 shares of the Company’s common stock were initially reserved for issuance under the 2021 ESPP. The shares available for issuance under the 2021 ESPP will be automatically increased on each January 1st, through January 1, 2031, by the least of (i) 439,849 shares of the Company’s common stock, (ii) 1 % of the outstanding number of shares of the Company’s common stock on the immediately preceding December 31st or (iii) such lesser number of shares of the Company’s common stock as determined by the plan administrator of the 2021 ESPP. Effective January 1, 2024 the number of shares available under the 2021 ESPP automatically increased by 439,849 shares pursuant to the evergreen provision of the 2021 ESPP. As of June 30, 2024, 1,064,399 shares were available for issuance under the 2021 ESPP. Stock option activity The following summarizes stock option activity: Number of Weighted Weighted Aggregate Outstanding—December 31, 2023 9,394,930 $ 8.78 8.0 $ 4,741 Granted 2,828,540 5.53 — — Exercised ( 235,268 ) 2.84 — — Forfeited ( 452,633 ) 7.99 — — Outstanding—June 30, 2024 11,535,569 $ 8.14 8.0 $ 1,836 Vested or expected to vest—June 30, 2024 11,535,569 $ 8.14 8.0 $ 1,836 Exercisable—June 30, 2024 5,353,616 $ 9.00 7.1 $ 1,598 The aggregate intrinsic value of options granted is calculated as the difference between the exercise price of the options and the estimated fair value of the Company’s common stock. Restricted stock award activity Unvested restricted stock awards were granted to employees under the 2020 Plan. Restricted stock awards generally vest over a four year period provided the individual remains in continuous service of the Company. The following summarizes restricted stock award activity: Number Weighted Unvested restricted stock awards as of December 31, 2023 14,696 $ 2.19 Vested ( 9,381 ) $ 2.19 Unvested restricted stock awards as of June 30, 2024 5,315 $ 2.19 The aggregate fair value of restricted stock awards that vested during the six months ended June 30, 2024 was immaterial and $ 0.5 million for the six months ended June 30, 2023. The weighted average grant date fair value of restricted stock awards that vested during the six months ended June 30, 2024 and 2023 was $ 2.19 and $ 0.76 , respectively. Restricted stock unit activity Starting in 2022, the Company granted restricted stock units, or RSUs, to employees under the 2021 Plan. Each of the RSUs represents the right to receive one share of the Company’s common stock upon vesting. The RSUs will vest over two years provided the individual remains in continuous service of the Company. Accordingly, stock-based compensation expense for each RSU is recognized on a straight-line basis over the vesting term. The fair value of each RSU is based on the closing price of the Company’s common stock on the date of grant. The following summarizes restricted stock unit activity: Number Weighted Unvested restricted stock units as of December 31, 2023 236,519 $ 8.00 Granted — $ — Vested ( 80,559 ) $ 7.55 Forfeited ( 2,326 ) $ 7.55 Unvested restricted stock units as of June 30, 2024 153,634 $ 8.24 The aggregate fair value of restricted stock units that vested during the six months ended June 30, 2024 was $ 0.3 million. The weighted average grant date fair value of restricted stock units that vested during six months ended June 30, 2024 was $ 7.55 . No restricted stock units vested during the six months ended June 30, 2023. Stock-based compensation expense Stock-based compensation expense is classified as follows (in thousands): Six months ended 2024 2023 Research and development $ 5,315 $ 4,411 General and administrative 4,060 3,716 Total stock-based compensation expense $ 9,375 $ 8,127 As of June 30, 2024 total unrecognized stock–based compensation cost related to unvested stock options and restricted stock units was $ 30.7 million and $ 0.9 million, respectively. The Company expects to recognize this remaining cost over a weighted average period of 2.6 years and 0.9 years, respectively. Unrecognized stock based compensation expense related to restricted stock awards was immaterial as of June 30, 2024. |