STOCK OPTIONS (Tables)

12 Months Ended

Dec. 31, 2015

STOCK OPTIONS

Schedule of assumptions used principally in determining the fair value of options granted

	December 31,
	2015	2014	2013
Risk-free interest rate	1.53 - 1.89%	1.62 - 2.06%	0.77 - 2.52%
Expected dividend yield	0%	0%	0%
Expected term (employee grants)	6.00 years	6.03 years	6.25 years
Expected volatility	116%	124%	102%

Summary of option activity

Options	Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term in Years		Aggregate Intrinsic Value
Outstanding at December 31, 2014		2,606,737		$	6.58
Granted		1,093,009		$	8.67
Forfeited		(92,997	)	$	8.66
Exercised		(353,439	)	$	4.28
Outstanding at December 31, 2015		3,253,310		$	7.47		8.08	$	3,416
Vested at December 31, 2015		1,349,752		$	6.81		6.65	$	2,459
Vested and expected to vest at December 31, 2015		2,625,248		$	7.37		7.82	$	3,073