Stock-Based Compensation Expense

9 Months Ended

Sep. 30, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation Expense

11. Stock-Based Compensation Expense

Total stock-based compensation expense recognized in the accompanying condensed consolidated statements of operations for the three and nine months ended September 30, 2018 and 2017 are as follows (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2018		2017		2018		2017
Stock-based compensation	$	1,562	$	1,247	$	5,715	$	3,763

During the three months ended September 30, 2018, the Company granted certain employees stock options to purchase an aggregate of 311,800 shares of common stock at a weighted average exercise price of $1.10 per share. The options vest over a four year period. The grant date fair value of these awards is $0.4 million with a weighted average grant date fair value of $1.39 per share, as determined using a Black-Scholes option pricing model.

As of September 30, 2018, there were $1.9 million and $8.6 million of unrecognized compensation expense related to restricted stock units and options, respectively, that vest over the vesting period.

During the three and nine months ended September 30, 2018, the Company recognized $0.3 million and $1.7 million, respectively, of compensation costs related to the performance-based stock options. As of September 30, 2018, there was $1.6 million of unrecognized compensation costs related to stock options subject to performance conditions. The Company evaluates stock awards with performance conditions as the probability that the performance conditions will be met and uses that information to estimate the date at which those performance conditions will be met in order to properly recognize stock-based compensation expense over the requisite service period.