Stock Compensation | 8. STOCK COMPENSATION In April 2021, the Company adopted the 2021 Employee Stock Purchase Plan (ESPP) and the 2021 Equity Incentive Plan (2021 EIP), each of which became effective in connection with the IPO. The Company has reserved 1,152,463 and 6,873,404 shares of Class A common stock for issuance under the ESPP and 2021 EIP, respectively. The Company may not grant any additional awards under the 2017 Equity Incentive Plan (2017 EIP). The 2017 EIP will continue to govern outstanding equity awards granted thereunder. As of June 30, 2024 , there were 663,680 shares available for issuance under the 2021 EIP. 2017 EIP and 2021 EIP Stock option activity under the 2017 EIP and 2021 EIP was as follows: Number of Options Weighted Average Exercise Price per Share Weighted Average Remaining Contractual Life (Years) Aggregate Intrinsic Value (000s) Outstanding as of December 31, 2023 5,762,236 $ 9.42 7.66 $ 39,197 Granted 1,973,100 Exercised ( 1,067,162 ) Cancelled and forfeited ( 419,602 ) Outstanding as of June 30, 2024 6,248,572 $ 12.52 8.30 $ 148,917 Options exercisable as of June 30, 2024 2,372,563 $ 8.64 7.38 $ 65,350 Vested and expected to vest as of June 30, 2024 6,248,572 $ 12.52 8.30 $ 148,917 The aggregate intrinsic value of stock options exercised during the three and six months ended June 30, 2024 , was approximately $ 10.6 and $ 31.2 million, respectively. The weighted average grant date fair value of options granted during the three and six months ended June 30, 2024 was $ 28.97 and $ 13.46 per share, respectively. ESPP The ESPP enables eligible employees to purchase shares of the Company’s common stock at the end of each offering period at a price equal to 85 % of the fair market value of the shares on the first trading day or the last trading day of the offering period, whichever is lower. Eligible employees generally include all employees. Share purchases are funded through payroll deductions of at least 1 % and up to 15 % of an employee’s eligible compensation for each payroll period. The number of shares reserved for issuance under the ESPP increases automatically on the first day of each fiscal year, beginning on January 1, 2022, by a number equal to the lesser of 440,502 shares, 1 % of the total number of shares of the Company’s capital stock (including all classes of the Company’s common stock) outstanding on the last day of the calendar month prior to the date of the increase, or such lower number of shares (including no shares) approved by the Company’s board of directors. As of June 30, 2024 , 80,989 shares have been issued pursuant to the ESPP. The ESPP generally provides for six-month consecutive offering periods beginning on September 14, 2021. The ESPP is a compensatory plan as defined by the authoritative guidance for stock compensation. Stock-based compensation expense related to the ESPP for the three and six months ended June 30, 2024 , was $ 0.1 million. Stock-Based Compensation Expense The following tables summarize the stock-based compensation expense for stock options and restricted stock units granted to employees and nonemployees and for ESPP stock-based compensation that was recorded in the Company’s condensed statements of operations and comprehensive loss for the three and six months ended June 30, 2024 and 2023. Three Months Ended Six Months Ended 2024 2023 2024 2023 Research and development $ 1,899 $ 1,231 $ 3,627 $ 2,365 General and administrative 2,974 1,451 5,370 2,984 Total stock-based compensation expense $ 4,873 $ 2,682 $ 8,997 $ 5,349 Three Months Ended Six Months Ended 2024 2023 2024 2023 Employees $ 4,261 $ 2,597 $ 8,132 $ 4,921 Nonemployees 612 85 865 428 Total stock-based compensation expense $ 4,873 $ 2,682 $ 8,997 $ 5,349 As of June 30, 2024 , the Company had $ 37.4 million of unrecognized stock-based compensation expense related to unvested stock options, which is expected to be recognized over a weighted-average period of approximately 2.8 years. The fair value of stock options granted during the three and six months ended June 30, 2024 and 2023, was estimated using the Black-Scholes option pricing model based on the following weighted-average assumptions. Three Months Ended Six Months Ended 2024 2023 2024 2023 Expected term (in years) 5.5 – 6.1 5.5 – 6.1 5.5 – 6.1 5.5 – 6.1 Expected volatility 71.9 % – 72.8 % 80.2 % – 80.5 % 67.7 % – 72.8 % 79.5 % – 80.5 % Risk-free rate 4.3 % – 4.6 % 3.4 % – 3.8 % 3.8 % – 4.6 % 3.4 % – 4.0 % Dividend yield — — — — Restricted Stock Units The Company grants restricted stock units (RSU) pursuant to the 2021 EIP and satisfies such grants through the issuance of its common stock. The following table shows RSU activity for the period ended June 30, 2024. Number of Shares Weighted Average Grant Date Fair Value per Share Unvested balance at December 31, 2023 131,679 $ 18.36 Granted 389,362 18.67 Vested ( 1,875 ) 15.46 Cancelled and forfeited ( 25,332 ) 18.03 Unvested balance at June 30, 2024 493,834 $ 18.63 For the six months ended June 30, 2024, the Company recognized $ 1.6 million of stock-based compensation for restricted stock units. As of June 30, 2024, the Company had $ 6.8 million of unrecognized stock-based compensation expense related to unvested RSUs, which is expected to be recognized over a weighted-average period of approximately 2.9 years. Inducement Plan In February 2024, the Company adopted the 2024 Inducement Plan (Inducement Plan). The Inducement Plan was adopted by the compensation committee of the Company’s board of directors without stockholder approval pursuant to Nasdaq Marketplace Rule 5635(c)(4). In accordance with Rule 5635(c)(4), awards made under the Inducement Plan, including stock options and restricted stock units, may only be granted to newly hired employees as a material inducement to accept employment with the Company. Awards granted under the Inducement Plan expire no later than ten years from the date of grant. An aggregate of 500,000 shares of common stock were reserved for issuance under the Inducement Plan. As of June 30, 2024, there were 430,175 shares available for issuance under the Inducement Plan. |