STOCK-BASED COMPENSATION

6 Months Ended

Jun. 30, 2015

Disclosure of Compensation Related Costs, Share-based 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 June 30,								For the Six Months Ended June 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*		367,167	$	15.69		117,770	$	23.68		1,974,711	$	11.34		1,303,035	$	19.80
Restricted stock awards		110,783	$	13.54		—	$	—		116,783	$	13.56		6,000	$	29.03

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

Stock-based Compensation Expense

For the three months ended June 30, 2015 and 2014, total stock-based compensation expense was $5.9 million and $5.6 million, respectively. For the six months ended June 30, 2015 and 2014, total stock-based compensation expense was $20.1 million and $9.9 million, respectively. Included in the amount for the six months ended June 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 June 30,				For the Six Months Ended June 30,
	2015		2014		2015		2014
	(in thousands)
Research and development	$	2,562	$	2,345	$	5,008	$	4,218
General and administrative		3,368		3,242		15,078		5,711
Total stock-based compensation expense	$	5,930	$	5,587	$	20,086	$	9,929

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 June 30,				For the Six Months Ended June 30,
	2015		2014		2015		2014
	(in thousands)
Stock options	$	5,099	$	5,042	$	18,650	$	8,953
Restricted stock awards		132		72		174		136
Restricted stock units		—		5		—		1
Stock appreciation rights		115		146		262		293
Employee stock purchase plan		584		322		1,000		546
Total stock-based compensation expense	$	5,930	$	5,587	$	20,086	$	9,929