Equity Incentive Plans (Tables)
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12 Months Ended |
Dec. 31, 2022 |
Share-Based Payment Arrangement [Abstract] |
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Summary of Fair Value of Stock Option Award Granted |
The following assumptions were used to estimate the fair value of stock option awards granted to employees under the Company’s equity incentive plans and the shares purchasable under the ESPP during the periods presented: | | | | | | | | | | | | | | | | | | | Year Ended December 31, | | 2022 | | 2021 | | 2020 | Employee Stock Options | | | | | | Expected term (in years) | 4.4 - 6.1 | | 4.6 - 6.1 | | 4.6 - 6.1 | Risk-free interest rate | 1.31% - 4.35% | | 0.65% - 1.30% | | 0.22% - 1.67% | Volatility | 71.10% - 89.87% | | 78.80% - 84.79% | | 84.38% - 87.23% | Dividend yield | — | | — | | — | | | | | | | Employee Stock Purchase Plan | | | | | | Expected term (in years) | 0.49 - 2.00 | | 0.49 - 2.00 | | 0.49 - 2.00 | Risk-free interest rate | 0.60% -3.51% | | 0.06% - 0.20% | | 0.12% - 0.95% | Volatility | 64.98% - 121.43% | | 61.29% - 87.13% | | 85.50% - 99.13% | Dividend yield | — | | — | | — |
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Summary of Stock Option Activity |
The following table summarizes stock option activity for the years ended December 31, 2022, 2021 and 2020: | | | | | | | | | | | | | | | | | | | | | | | | | Shares Subject to Options Outstanding | | Weighted- Average Remaining Contractual Life (Years) | | Aggregate Intrinsic Value | | Shares | | Weighted- Average Exercise Price | | | | | | | | | | (in thousands) | Outstanding as of December 31, 2019 | 8,538,060 | | | $ | 13.67 | | | 9.0 | | $ | 35,385 | | Options granted | 2,712,372 | | | $ | 13.78 | | | | | | Options exercised | (134,803) | | | $ | 3.96 | | | | | | Options forfeited/cancelled | (1,714,547) | | | $ | 15.99 | | | | | | Outstanding as of December 31, 2020 | 9,401,082 | | | $ | 13.42 | | | 8.1 | | $ | 10,182 | | Options granted | 3,159,126 | | | $ | 9.82 | | | | | | Options exercised | (325,494) | | | $ | 6.19 | | | | | | Options forfeited/cancelled | (2,800,054) | | | $ | 14.14 | | | | | | Outstanding as of December 31, 2021 | 9,434,660 | | | $ | 12.24 | | | 7.4 | | $ | 15,822 | | Options granted | 9,271,272 | | | $ | 6.75 | | | | | | Options exercised | (270,707) | | | $ | 6.41 | | | | | | Options forfeited/cancelled | (948,060) | | | $ | 15.69 | | | | | | Outstanding as of December 31, 2022 | 17,487,165 | | | $ | 9.24 | | | 8.1 | | $ | 47 | | Options vested and expected to vest as of December 31, 2022 | 17,487,165 | | | $ | 9.24 | | | 8.1 | | $ | 47 | | Options exercisable as of December 31, 2022 | 6,433,686 | | | $ | 12.19 | | | 6.4 | | $ | — | |
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Summary of Restricted Stock Activity |
The summary of the Company’s restricted stock activity during the years ended December 31, 2022, 2021 and 2020 is as follows: | | | | | | | | | | | | | Number of Restricted Stock Units Outstanding | | Weighted- Average Grant Date Fair Value | Nonvested at December 31, 2019 | 4,648,526 | | | $ | 3.98 | | Granted | 2,003,900 | | | 10.96 | | Vested | (2,557,377) | | | 4.00 | | Forfeited / cancelled | (764,228) | | | 8.30 | | Nonvested at December 31, 2020 | 3,330,821 | | | $ | 7.16 | | Granted | 1,349,885 | | | 10.23 | | Vested | (1,391,476) | | | 5.86 | | Forfeited / cancelled | (728,011) | | | 10.03 | | Nonvested at December 31, 2021 | 2,561,219 | | | $ | 8.67 | | Granted | 572,901 | | | 11.94 | | Vested | (1,592,588) | | | 7.78 | | Forfeited / cancelled | (191,497) | | | 10.68 | | Nonvested at December 31, 2022 | 1,350,035 | | | $ | 10.83 | |
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Stock-Based Compensation Expense Reported in Condensed Consolidated Statements of Operations |
Stock-based compensation expense has been reported in the Company’s consolidated statements of operations and comprehensive loss as follows (in thousands): | | | | | | | | | | | | | | | | | | | Year Ended December 31, | | 2022 | | 2021 | | 2020 | Research and development | $ | 24,415 | | | $ | 18,943 | | | $ | 18,997 | | General and administrative | 18,138 | | | 13,065 | | | 19,751 | | Total stock-based compensation expense | $ | 42,553 | | | $ | 32,008 | | | $ | 38,748 | |
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