STOCK-BASED COMPENSATION

9 Months Ended

Sep. 30, 2015

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

STOCK-BASED COMPENSATION

8. STOCK-BASED COMPENSATION

The following table summarizes the Company’s stock awards granted for each of the periods indicated:

	For the Three Months Ended September 30,								For the Nine Months Ended September 30,
	2015				2014				2015				2014
	Grants		Weighted Average Grant Date Fair Value		Grants		Weighted Average Grant Date Fair Value		Grants		Weighted Average Grant Date Fair Value		Grants		Weighted Average Grant Date Fair Value
Stock options*		702,067	$	24.05		237,050	$	16.19		2,676,778	$	14.67		1,540,085	$	19.24
Restricted stock awards**		65,000	$	33.81		—	$	—		181,783	$	20.80		6,000	$	29.03

* A majority of the stock options granted during the periods presented in the table have only service-based criteria and vest over four years.

** In September 2015, the Company granted certain employees restricted stock awards (“RSAs”) with performance conditions. If certain performance milestones are achieved within the required time frame, the number of RSAs with performance conditions may be increased from 65,000 to 97,500 shares. As a result, the Company may recognize up to $3.3 million of stock-based compensation related to these grants when performance is deemed probable.

Stock-based Compensation Expense

For the three months ended September 30, 2015 and 2014, total stock-based compensation expense was $5.7 million and $4.6 million, respectively. For the nine months ended September 30, 2015 and 2014, total stock-based compensation expense was $25.8 million and $14.6 million, respectively. Included in the amount for the nine months ended September 30, 2015 is $8.6 million of stock-based compensation expense incurred in connection with the resignation of the Company’s former Chief Executive Officer (“CEO”). The following table summarizes stock-based compensation expense by function included within the unaudited condensed consolidated statements of operations and comprehensive loss: 

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2015		2014		2015		2014
	(in thousands)
Research and development	$	2,631	$	1,668	$	7,639	$	5,886
General and administrative		3,052		2,981		18,130		8,692
Total stock-based compensation expense	$	5,683	$	4,649	$	25,769	$	14,578

The following table summarizes stock-based compensation expense by grant type included within the unaudited condensed consolidated statements of operations and comprehensive loss:

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2015		2014		2015		2014
	(in thousands)
Stock options	$	4,801	$	4,217	$	23,451	$	13,170
Restricted stock awards		136		33		310		169
Restricted stock units		—		—		—		1
Stock appreciation rights		115		147		377		440
Employee stock purchase plan		631		252		1,631		798
Total stock-based compensation expense	$	5,683	$	4,649	$	25,769	$	14,578