v3.24.1.u1
Equity Incentive Plans and Stock-Based Compensation (Tables)
 3 Months Ended
Mar. 31, 2024
Share-Based Payment Arrangement [Abstract]  
Schedule of Black-Scholes Option Pricing Model to Estimate Stock-based Compensation Expense for Stock Option Awards
The Company used Black-Scholes option pricing model to estimate stock-based compensation expense for stock option awards with the following assumptions:
  Three months ended March 31,
 20242023
Expected volatility
85.28% - 86.42%
80.97% - 81.41%
Risk-free interest rate
4.04% - 4.28%
3.42% - 4.18%
Expected dividend——
Expected term (in years)
5.99 - 6.06
5.77 - 6.08
Underlying common stock fair value
$15.19 - $17.44
$21.94 - $34.65
Schedule of Option Activity Under the 2015 Plan and 2020 Plan
A summary of option activity under the 2015 Plan and the 2020 Plan is as follows:
  Number
of
Options		Weighted-
Average Exercise
Price per Share		Weighted-
Average
Remaining
Contractual
Term (in Years)		Aggregate
Intrinsic
Value
Outstanding as of December 31, 20236,953,487 $17.95 7.70$32,646 
Granted1,338,465 $17.29 
Exercised(118,573)$8.01 
Forfeited(513,519)$16.87 
Outstanding as of March 31, 20247,659,860 $18.06 7.83$18,505 
Exercisable as of March 31, 20247,659,860 $18.06 7.83$18,505 
Vested and expected to vest as of March 31, 20243,651,242 $15.84 6.70$15,456 
Schedule of Restricted Stock Activity The following table sets forth the outstanding RSUs and related activity for the three months ended March 31, 2024
Restricted Stock UnitsWeighted Average Grant Date Fair Value
Unvested and outstanding as of December 31, 2023874,748 $29.85 
Granted594,336 $17.44 
Released(210,085)$34.65 
Forfeited(57,275)$27.88 
Unvested and outstanding as of March 31, 20241,201,724 $22.97 
Schedule of Share-Based Payment Award, Equity Instruments Other Than Options, Valuation Assumptions
The fair value of the TSR PSUs were derived from a Monte Carlo simulation model that used the following key assumptions:
Valuation date share price$17.57 
Award term (years)1.92
Volatility70.62 %
Correlation coefficient0.3508
Average peer group volatility79.69 %
Average peer group correlation coefficient0.4397
Risk-free interest rate
2.84 %
Share-Based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity
The following table sets forth the outstanding PSUs associated with TSR goal and related activity during the three months ended March 31, 2024:
Performance Stock UnitsWeighted Average Grant Date Fair Value
Unvested balance at December 31, 2023328,752 $29.15
Forfeited(46,407)$29.15
Unvested balance at March 31, 2024282,345 $29.15
Schedule of Black-Scholes Option Pricing Model to Estimate Stock-based Compensation Expense for 2020 Employee Stock Purchase Plan The Company used Black-Scholes option pricing model to estimate stock-based compensation expense for the 2020 ESPP with the following assumptions:
  Three months ended March 31,
 20242023
Risk-free interest rate
5.27%
5.20%
Expected term of options (in years)0.500.50
Expected stock price volatility
63.92%
69.15%
Expected dividends——
Schedule of Classification of Stock-based Compensation Expense
The following table presents the components and classification of stock-based compensation expense for the Company’s stock-based awards for the three months ended March 31, 2024 and 2023 (in thousands):
Three Months Ended
March 31,
20242023
Stock options and ESPP$6,358 $4,803 
Restricted stock units3,246 2,606 
Performance-based restricted stock units62 4,514 
Total stock-based compensation expense$9,666 $11,923 
Research and development expenses$3,070 $4,848 
General and administrative expenses$6,596 $7,075