The Company maintains a stock-based compensation plan, the 2011 Incentive Compensation Plan (the “2011 Plan”), as amended, to attract, motivate, retain and reward employees, directors and consultants by providing its Board or a committee of the Board the discretion to award equity incentives to these persons.

A summary of stock option activity for the three months ended March 31, 2023 is as follows:


	Number Outstanding		Weighted Average Exercise Price per Share		Weighted Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value
Balance as of January 1, 2023		505,593	$	5.05		3.17	$	1,280,805
Granted		—		—
Cancelled or Expired		—		—
Exercised		—		—
Balance as of March 31, 2023		505,593	$	5.05		2.93	$	791,309
Vested or expected to vest as of March 31, 2023		505,593	$	5.05		2.93	$	791,309
Exercisable as of March 31, 2023		505,593	$	5.05		2.93	$	791,309

The aggregate intrinsic value in the table above represents the difference between the fair value of the Company’s common stock as of March 31, 2023 and the exercise price of in-the-money stock options multiplied by the number of such stock options.

The following table summarizes information about stock options outstanding as of March 31, 2023:


	Stock Options Outstanding						Stock Options Exercisable
Range of Exercise Prices	Number Outstanding		Weighted Average Remaining Contractual Life (Years)		Weighted Average Exercise Price		Number Exercisable		Weighted Average Exercise Price
$4.36 - $7.20		445,960		3.18	$	4.37		445,960	$	4.37
$7.50 - $11.25		59,100		1.05		10.17		59,100		10.17
$11.30 - $16.95		500		1.00		11.30		500		11.30
$19.70 - $29.55		33		0.38		19.70		33		19.70
$4.36 - $29.55		505,593		2.93	$	5.05		505,593	$	5.05

As of March 31, 2023, there was no unrecognized stock-based compensation expense related to stock options.

The following is a summary of RSU activity for the three months ended March 31, 2023:


	Number Outstanding			Weighted Average Fair Value
Unvested as of January 1, 2023		819,185		$	13.23
Granted		151,123			6.96
Vested		(84,816	)		13.35
Forfeited		(12,729	)		12.62
Unvested as of March 31, 2023		872,763		$	12.14
RSUs vested but not released		137,768		$	7.00

The fair value of the Company’s RSUs is calculated based upon the fair market value of the Company’s common stock at the date of grant. As of March 31, 2023, there was $8.6 million of unrecognized compensation expense related to unvested RSUs granted, which is expected to be recognized over a weighted average period of 3.1 years. No tax benefit was realized from RSUs for the three months ended March 31, 2023.

The Company grants PSUs to certain key employees that are subject to the attainment of performance goals established by the Company’s Compensation Committee, the periods during which performance is to be measured, and other limitations and conditions. Performance goals are based on pre-established objectives that specify the manner of determining the number of PSUs that will vest if performance goals are attained. If an employee terminates employment, the non-vested portion of the PSUs will not vest and all rights to the non-vested portion will terminate.

The following is a summary of PSU activity for the three months ended March 31, 2023:


	Number Outstanding		Weighted Average Fair Value
Unvested as of January 1, 2023		40,000	$	8.51
Granted		—		—
Vested		—		—
Forfeited		—		—
Unvested as of March 31, 2023		40,000	$	8.51

As of March 31, 2023, there was $0.2 million of unrecognized compensation expense related to unvested PSUs, which is expected to be recognized over a period of 0.75 years. No tax benefit was realized from PSUs for the three months ended March 31, 2023.

The following table summarizes stock-based compensation expense related to stock options, RSUs, and PSUs included in the condensed consolidated statements of comprehensive income (loss) for the three months ended March 31, 2023 and 2022 (in thousands):


	Three Months Ended March 31,
	2023		2022
Cost of revenue	$	45	$	56
Research and development		202		310
Selling and marketing		293		194
General and administrative		450		335
Total	$	990	$	895

During the three months ended March 31, 2023 and 2022, the Company repurchased 24,812 and 17,647 shares, respectively, of common stock surrendered to the Company to satisfy tax withholding obligations in connection with the vesting of RSUs issued to employees.