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Stock-Based Compensation
 3 Months Ended
Mar. 31, 2024
Share-Based Payment Arrangement [Abstract]  
Stock-Based Compensation STOCK-BASED COMPENSATION
Common Stock Outstanding and Reserves for Future Issuance
As of March 31, 2024, the Company had 37,749,468 shares of common stock issued and outstanding, which excludes 312,500 of pre-funded warrants that remain exercisable at period end and are reserved for future issuance. As of December 31, 2023 the Company had 34,211,190 shares of common stock issued and outstanding, respectively. Each share of common stock is entitled to one vote.
The Company's outstanding equity awards and shares reserved for future issuance under its 2020 and 2016 Equity Incentive Plans and 2020 Employee Stock Purchase Plan are summarized below:
March 31, 2024December 31, 2023
Common stock awards reserved for future issuance under 2020 and 2016 Equity Incentive Plans7,435,442 7,054,222 
Common stock awards reserved for future issuance under the 2020 Employee Stock Purchase Plan2,859,434 2,859,434 
Stock options issued and outstanding (unvested and vested) under 2020 and 2016 Equity Incentive Plans5,217,617 4,760,366 
Restricted stock units issued and outstanding (unvested) under 2020 Equity Incentive Plan1,981,673 1,708,725 
Total shares of common stock reserved17,494,166 16,382,747 
Stock-Based Compensation Expense
Stock-based compensation expense was recognized in the accompanying Condensed Statements of Operations and Comprehensive Loss as follows:
Three Months Ended March 31,
20242023
Cost of sales$135 $— 
Research and development1,465 1,163 
Selling, general and administrative3,919 2,743 
Total stock-based compensation$5,519 $3,906 
The fair value of granted stock options was estimated as of the date of grant using the Black-Scholes option-pricing model, based on the following inputs:
Three Months Ended March 31,
20242023
Expected term (in years)6.256.25
Weighted average risk-free interest rate4.08 %4.20 %
Weighted average volatility71.23 %71.9 %
Dividend yield rate— %— %
Weighted-average grant-date fair value per stock option$35.09 $15.07 
Stock Option Activity
Stock option activity during the three months ended March 31, 2024 was as follows:
Number of
Shares		Weighted-
Average
Exercise
Price/Share		Weighted-
Average
Remaining
Contractual
Term (Years)
Aggregate
Intrinsic
Value(1)
Outstanding - December 31, 20234,760,366 $16.62 7.53$34,128 
Granted633,887 $35.09 
Exercised(49,310)$16.21 
Forfeited(127,326)$18.03 
Expired— — 
Outstanding— March 31, 20245,217,617 $18.83 7.46$96,254 
Exercisable— March 31, 20242,972,207 $15.51 6.41$65,826 
Unvested—March 31, 20242,245,410 $23.22 8.86$30,428 
(1) The aggregate intrinsic value is calculated as the difference between the exercise price of the options and the fair value of the Company’s common stock as of March 31, 2024.
As of March 31, 2024, there was approximately $33.0 million of unrecognized compensation expense related to unvested stock options, which the Company expects to recognize over a weighted average period of 2.6 years.
Restricted Stock Unit Activity
Restricted stock unit activity during the three months ended March 31, 2024 was as follows:
Number of
Shares		Weighted-
Average
Exercise
Price/Share
Outstanding - December 31, 20231,708,725 $16.31 
Granted596,726 $36.03 
Vested(207,718)$16.11 
Forfeited(116,060)$17.62 
Outstanding— March 31, 20241,981,673 $22.19 
As of March 31, 2024, there was approximately $41.0 million of unrecognized compensation expense related to unvested restricted stock units, which the Company expects to recognize over a weighted average period of 3.5 years.
Employee Stock Purchase Plan ("ESPP")
Stock-based compensation expense related to the ESPP was $0.2 million and $0.1 million, respectively, for the three months ended March 31, 2024 and 2023.