DERIVATIVE INSTRUMENTS (Tables)

6 Months Ended

Jun. 30, 2015

DERIVATIVE INSTRUMENTS

Assumptions used in determining fair value of warrants

	June 30, 2015
Risk-free interest rate	1.27	%
Expected dividend yield	0.00	%
Expected term (in years)	3.86
Expected volatility	115.31	%

Changes in derivative warrant liability

Changes in the derivative warrant liability for the six months ended June 30 are as follows (in thousands):

	Six Months Ended June 30,
	2015			2014
Balance at December 31,	$	7,224		$	—
Fair value of warrants issued	—			6,848
Reduction in derivative liability due to exercise and modification of warrants	(14,442		)	—
Increase (decrease) in the fair value of warrants	14,940			(1,127		)
Balance at June 30,	$	7,722		$	5,721