Stock-Based Compensation

6 Months Ended

Jun. 30, 2020

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				Six Months Ended
	June 30,				June 30,
	2020		2019		2020		2019
Cost of revenues	$	277	$	73	$	396	$	142
Selling, general and administrative		1,030		506		1,467		1,025
Research and development		629		187		783		372

Total stock-based compensation	$	1,936	$	766	$	2,646	$	1,539

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


	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2020		2019		2020		2019
Stock options	$	1,737	$	509	$	2,243	$	1,042
ESPP		199		257		403		497

Total stock-based compensation	$	1,936	$	766	$	2,646	$	1,539

The increase in stock option compensation expense for the three and six months ended June 30, 2020 compared to the three and six months ended June 30, 2019, was primarily due to an increase in the number of stock options granted and to the acceleration of

recognition of

compensation expense on stock options granted to retirement eligible employees.