Stock-Based Compensation

9 Months Ended

Sep. 30, 2021

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

The Company uses the Black-Scholes option pricing model to calculate the fair value of stock option awards, whether they possess time-based vesting provisions or performance-based vesting provisions, and awards granted under the Vicor Corporation 2017 Employee Stock Purchase Plan (“ESPP”), as of their grant date. Stock-based compensation expense was as follows (in thousands):


	Three Months Ended				Nine Months Ended
	September 30,				September 30,

	2021		2020		2021		2020

Cost of revenues	$	259	$	296	$	739	$	692
Selling, general and administrative		1,033		846		2,665		2,313
Research and development		575		498		1,601		1,281

Total stock-based compensation	$	1,867	$	1,640	$	5,005	$	4,286

Compensation expense by type of award was as follows (in thousands):


	Three Months Ended				Nine Months Ended
	September 30,				September 30,

	2021		2020		2021		2020

Stock options	$	1,661	$	1,420	$	4,328	$	3,663
ESPP		206		220		677		623

Total stock-based compensation	$	1,867	$	1,640	$	5,005	$	4,286

The increase in stock option compensation expense for the three and nine months ended September 30, 2021 compared to the three and nine months ended September 30, 2020, was primarily due to an increase in the number of stock options granted and higher stock-based compensation expense associated with June 2021 stock opti

n awards.