Common Stock and Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2023

Share-Based Payment Arrangement [Abstract]

Summary of stock options, RSU and PSU activity

A summary of stock option, RSU and PSU activity under the 2014 Plan during the six months ended June 30, 2023 and 2022 is presented below:

	Stock Options	RSUs	PSUs
Outstanding as of December 31, 2021	2,814,878	263,306	137,300
Granted	91,700	148,000	228,200
Stock options exercised/RSUs vested/PSUs vested	(62,321)	(101,898)	—
Forfeited or expired	(40,044)	(7,082)	—
Outstanding as of June 30, 2022	2,804,213	302,326	365,500
Outstanding as of December 31, 2022	2,425,833	269,163	319,100
Granted	116,268	253,700	211,800
Stock options exercised/RSUs vested/PSUs vested	(26,672)	(105,071)	—
Forfeited or expired	(44,674)	(16,875)	—
Outstanding as of June 30, 2023	2,470,755	400,917	530,900

Fair value of stock options

The fair value of stock options granted to employees, directors, and consultants were estimated using the following assumptions:

	Three Months Ended June 30,		Six Months Ended   June 30,
	2023	2022	2023	2022
Risk-free interest rate	3.49% - 3.63%	3.00% - 3.31%	3.49% - 4.23%	1.47% - 3.31%
Volatility	45.71%	48.42%	44.31%	46.88%
Expected term (in years)	6.08 years	6.08 years	5.59 years	5.65 years
Expected dividend yield	0.0%	0.0%	0.0%	0.0%

Share-based payment arrangement, cost by plan

We recognized stock-based compensation in our condensed consolidated statements of operations for the three and six months ended June 30, 2023 and 2022 as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2023		2022		2023		2022
Stock options	$	1,143	$	1,671	$	2,624	$	3,534
RSUs	1,203		1,289		2,850		2,924
PSUs	1,846		1,540		3,357		2,337
Stock-based compensation expense	$	4,192	$	4,500	$	8,831	$	8,795
Selling, general and administrative	$	3,665	$	3,899	$	7,617	$	7,551
Research and development	527		601		1,214		1,244
Stock-based compensation expense	$	4,192	$	4,500	$	8,831	$	8,795