STOCK-BASED COMPENSATION

9 Months Ended

Sep. 30, 2019

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

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION

The following table presents stock-based compensation expense recognized for stock options, stock awards, RSUs, PSUs and the Company’s ESPP in the Company’s Condensed Consolidated Statements of Operations (in thousands): 

	Three Months Ended September 30,					Nine Months Ended September 30,
	2019		2018			2019		2018
Cost of sales	$	28	$	—		$	78	$	30
Research and development expense	165		270			514		337
Selling, general and administrative expense	2,811		2,674			7,748		7,523
Restructuring	—		(173		)	—		2,385
Total	$	3,004	$	2,771		$	8,340	$	10,275

At September 30, 2019, the Company had $1.5 million of total unrecognized compensation expense related to stock option grants that will be recognized over an average vesting period of 2.24 years and $18.0 million of total unrecognized compensation expense related to RSUs and PSUs that will be recognized over an average vesting period of 2.59 years.

During the nine months ended September 30, 2019 the Company granted 2.5 million RSUs at an average fair market value of $4.11 per share and 0.6 million PSUs at an average fair market value of $6.87 per share. The fair value of restricted stock units is determined using the closing stock price on the date of grant and the fair value of the performance RSUs is determined using a Monte Carlo simulation method.