Stock-Based Compensation Plan (Tables)

6 Months Ended

Jun. 30, 2022

Stock-Based Compensation Plan

Summary of weighted-average assumptions

The Company utilized the Black-Scholes valuation model for estimating the fair value of the stock options granted, with the following weighted-average assumptions for options granted in the six months ended June 30, 2022 and 2021, respectively:

	2022		2021
Risk-free interest rate	2.43	%	1.18	%
Expected volatility	127	%	127	%
Expected term in years	6.0		6.1
Dividend yield	—	%	—	%

Schedule of option activity under stock-based compensation plans

The following summary represents option activity under the Company’s stock-based compensation plans for the six months ended June 30, 2022:

		Weighted-
		Average
		Exercise
	Options	Price
	(in thousands)
Outstanding at December 31, 2021	486	$	14.58
Granted	192		3.71
Forfeited	(2)		7.02
Expired	(18)		5.96
Outstanding at June 30, 2022	658	$	11.67
Vested and expected to vest June 30, 2022	622	$	12.02
Exercisable at June 30, 2022	257	$	21.70