DERIVATIVE INSTRUMENTS (Tables)

3 Months Ended

Mar. 31, 2015

DERIVATIVE INSTRUMENTS

Assumptions used in determining fair value of warrants

	March 31, 2015
Risk-free interest rate	1.15	%
Expected dividend yield	0.00	%
Expected term (in years)	4.11
Expected volatility	116.99	%

Changes in derivative warrant liability

Changes in the derivative warrant liability for the three months ended March 31 are as follows (in thousands):

	Three Months Ended March 31,
	2015			2014
Balance at December 31,	$	7,224		$	—
Fair value of warrants issued	—			—
Reduction in derivative liability due to exercise and modification of warrants	(4,866		)	—
Increase (decrease) in the fair value of warrants	10,286			—
Balance at March 31,	$	12,644		$	—