Stock-Based Compensation

9 Months Ended

Sep. 30, 2021

Share-based Payment Arrangement [Abstract]

The Company grants equity-based awards to employees, non-employee directors, and consultants that may include, but are not limited to, RSA's, restricted stock units ("RSU's"), performance stock units ("PSU's") and stock options. Stock-based compensation expense related to manufacturing employees and administrative employees is included within the Cost of revenue and Payroll and benefits line items, respectively, in the Condensed Consolidated Statements of Operations. Stock-based compensation expense related to non-employee directors and consultants is included within the General and administrative line item in the Condensed Consolidated Statements of Operations.

Total stock-based compensation expense for the three and nine months ended September 30, 2021 and 2020 was as follows:


	Three Months Ended September 30,				Nine Months Ended September 30,
(in thousands)	2021		2020		2021		2020
RSA expense	$	435	$	411	$	1,353	$	1,892

PSU expense	54		15		123		178

Total stock-based compensation expense	$	489	$	426	$	1,476	$	2,070

The amount of unrecognized compensation cost as of September 30, 2021, and the expected weighted-average period over which the cost will be recognized is as follows:


	As of September 30, 2021
(in thousands)	Unrecognized Compensation Cost		Expected Weighted- Average Period of Recognition (in years)
RSA expense	$	2,558	2.01

PSU expense	438		1.99

Total unrecognized stock-based compensation expense	$	2,996	2.01

Restricted Stock

Restricted stock is typically granted with vesting terms of three years. The fair value of RSA's and RSU's is determined based on the closing price of the Company’s common stock on the authorization date of the grant multiplied by the number of shares subject to the stock award. Compensation expense for RSA's is generally recognized on a straight-line basis over the entire vesting period.

A summary of RSA activity under the Company's various stock compensation plans for the nine months ended September 30, 2021 is presented below:


	Restricted Stock	Weighted-Average Grant Date Fair Value

Non-vested at January 1, 2021	373,860	$	7.25
Granted	441,109	$	5.53
Vested	(193,624)	$	7.44
Forfeited	(54,299)	$	5.80
Non-vested at September 30, 2021	567,046	$	5.99

Performance Share Units

Compensation expense is recognized for PSU awards on a straight-line basis over the applicable service period, which is generally three years, based on the estimated fair value at the date of grant using a Monte Carlo simulation model. A summary of PSU activity for the nine months ended September 30, 2021 is presented below:


	Units	Weighted-Average Grant Date Fair Value		Aggregate Intrinsic Value (in thousands)		Weighted-Average Remaining Contractual Term (in years)
PSU's outstanding, January 1, 2021	50,127	$	6.17
Granted	62,448	7.09
Vested / Settled	—	—
Forfeited / Canceled	—	—
PSU's outstanding, September 30, 2021	112,575	$	6.68	$	719	1.99