Warrants (Tables)

6 Months Ended

Jun. 30, 2014

Number of Warrants Outstanding

The number of warrants outstanding at June 30, 2014 and December 31, 2013 were as follows:

	June 30, 2014		December 31, 2013
Liability-classified warrants		8,235,076		8,235,076
Equity-classified warrants		2,261,391		2,304,691
Total warrants		10,496,467		10,539,767

Assumptions Used in Binomial and Monte Carlo Valuation Model

The following assumptions were used in the Binomial/Monte Carlo valuation model at June 30, 2014 and 2013:

	June 30, 2014			June 30, 2013
Risk-free interest rate		0.06	%		0.26	%
Expected life in years		0.44			1.44
Expected volatility		70	%		70	%
Expected dividend yield		0			0
Steps per year		54			12

Warrant Exercises

During the six months ended June 30, 2014, warrant exercises were as follows:

(in thousands, except share data)	Equity Warrants		Liability Warrants		Common Stock Issued		Liability Reclassed to Equity		Cash Received
Cash exercises		—		—		—	$	—	$	—
Cashless exercises		43,300		—		21,977		—		—
		43,300		—		21,977	$	—	$	—

During the six months ended June 30, 2013, warrant exercises were as follows:

(in thousands, except share data)	Equity Warrants		Liability Warrants		Common Stock Issued		Liability Reclassed to Equity		Cash Received
Cash exercises		49,315		—		49,315	$	—	$	101
Cashless exercises		—		—		—		—		—
		49,315		—		49,315	$	—	$	101