STOCKHOLDERS' EQUITY (Tables)

12 Months Ended

Dec. 31, 2016

Stockholders' Equity Note [Abstract]

Schedule of warrant activity

Summary of our Warrant activity during the year ended December 31, 2016:

	Number of Shares Under Warrants			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life in Years		Aggregate Intrinsic Value
Balance at December 31, 2015		12,722,431		$	1.93		1.7	$	107,344,752
Granted		245,000		$	7.90
Exercised		(722,744	)	$	1.90			$	3,988,343
Expired		(184,616	)	$	0.41
Cancelled/Forfeited		—
Balance at December 31, 2016		12,060,071		$	2.08		1.0	$	45,063,867
Vested and Exercisable at December 31, 2016		11,733,410		$	2.06		1.0	$	43,998,535
Unvested at December 31, 2016		326,661		$	2.81		1.7	$	1,065,332

Schedule of assumptions used in the Black-Scholes Model of warrants

The weighted average fair value per share of warrants issued and the assumptions used in the Black-Scholes Model during the years ended December 31, 2016, 2015 and 2014 are set forth in the table below.

	2016	2015	2014
Weighted average price	$7.90	$6.35	n/a
Weighted average grant date fair value	$4.78	$3.27	n/a
Risk-free interest rate	1.04-1.28%	1.02%	n/a
Volatility	74.10-74.15%	60.59%	n/a
Term (in years)	5	5	n/a
Dividend yield	0.00%	0.00%	n/a

Schedule of assumptions used in the Black-Scholes Model of stock options

The ranges of assumptions used in the Black-Scholes Model during the years ended December 31, 2016, 2015, and 2014 are set forth in the table below.

	2016	2015	2014
Risk-free interest rate	1.13-1.90%	1.47-1.67%	0.07-1.77%
Volatility	70.26-73.34%	58.78-62.94%	68.05-82.29%
Term (in years)	5.5-6.25	5.27-6.25	5-6.25
Dividend yield	0.00%	0.00%	0.00%

Schedule of plan activity

A summary of activity under the 2009 and 2012 Plans and related information during the year ended December 31, 2016 is as follows:

	Number of Shares Under Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life in Years		Aggregate Intrinsic Value
Balance at December 31, 2015		20,725,325		$	3.28		6.5	$	146,864,184
Granted		1,732,500		$	6.22
Exercised		(652,471	)	$	1.91			$	3,828,358
Expired		(5,750	)	$	4.76
Cancelled/Forfeited		(31,750	)	$	6.38
Balance at December 31, 2016		21,767,854		$	3.56		5.8	$	60,495,730
Vested and Exercisable at December 31, 2016		18,633,479		$	3.09		5.3	$	59,382,849
Unvested at December 31, 2016		3,134,375		$	6.29		9.0	$	1,112,881