STOCKHOLDERS' EQUITY (Tables)

6 Months Ended

Jun. 30, 2017

Stockholders' Equity:

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

The assumptions used in the Black-Scholes Model for options granted during the six months ended June 30, 2017 and 2016 are set forth in the table below.

	Six Months Ended
	June 30, 2017	June 30, 2016
Risk-free interest rate	1.84-2.01%	1.26-1.70%
Volatility	61.56-63.95%	70.44-71.22%
Term (in years)	5.5-6.25	6.25
Dividend yield	0.00%	0.00%

Schedule of plan activity

A summary of activity under the 2009 and 2012 Plans and related information follows:

	Number of Shares Underlying Stock Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life in Years		Aggregate Intrinsic Value
Balance at December 31, 2016		21,767,854		$	3.56		5.8	$	60,495,730
Granted		2,184,500		$	6.61
Exercised		(100,046	)	$	2.12			$	437,667
Expired/Forfeited		(450,208	)	$	6.54
Balance at June 30, 2017		23,402,100		$	3.79		5.6	$	52,165,428
Vested and Exercisable at June 30, 2017		18,731,808		$	3.13		4.9	$	51,750,547
Unvested at June 30, 2017		4,670,292		$	6.43		8.8	$	414,881