Stock-Based Awards (Tables)

6 Months Ended

Jun. 30, 2021

Stock-Based Awards

Assumptions used to determine fair value of stock options granted

	Six Months Ended
	June 30,
	2021		2020
Risk-free interest rate	0.91	%	0.87	%
Expected term (in years)	6.2		6.1
Expected volatility	76.60	%	85.19	%
Expected dividend yield	0	%	0	%

Summary of stock option activity

				Weighted
		Weighted		Average
		Average		Remaining	Aggregate
	Number	Exercise		Contractual	Intrinsic
(In thousands, except share and per share data and years)	of Shares	Price		Term	Value
				(in years)
Outstanding as of December 31, 2020	2,871,498	$	15.16	6.8	$	4,890
Granted	993,600		23.88
Exercised	(115,548)		12.63		$	1,373
Forfeited and cancelled	(10,925)		21.78
Outstanding as of June 30, 2021	3,738,625	$	17.54	7.2	$	17,541
Options vested and expected to vest as of June 30, 2021	3,738,625	$	17.54	7.2	$	17,541
Options exercisable as of June 30, 2021	2,044,235	$	17.51	5.8	$	10,090

Summary of restricted stock units activity

		Weighted
		Average
		Grant Date		Aggregate
	Number	Fair Value		Intrinsic
(In thousands, except share and per share data)	of Shares	Per Share		Value
Outstanding as of December 31, 2020	2,244,157	$	3.83
Granted	607,148		24.00
Vested	(1,314,214)		2.87	$	31,049
Forfeited and cancelled	(38,375)		6.86
Outstanding as of June 30, 2021	1,498,716	$	12.76

Stock-based compensation expense

	Three Months Ended				Six Months Ended
	June 30,				June 30,
(In thousands)	2021		2020		2021		2020
Cost of revenue	$	335	$	252	$	582	$	512
Research and development		1,154		939		2,030		1,755
General and administrative		2,343		2,118		3,895		4,495
Total stock-based compensation expense	$	3,832	$	3,309	$	6,507	$	6,762