Warrants (Tables)

3 Months Ended

Mar. 31, 2013

Number of Warrants Outstanding

The number of warrants outstanding at March 31, 2013 and December 31, 2012 were as follows:

	March 31, 2013		December 31, 2012
Liability-classified warrants		8,050,709		8,050,709
Equity-classified warrants		3,097,430		3,146,745
Total warrants		11,148,139		11,197,454

Assumptions Used In Binomial and Monte Carlo Valuation Model

The following assumptions were used in the Binomial/Monte Carlo valuation model at March 31, 2013 and 2012:

	March 31, 2013	March 31, 2012
Risk-free interest rate	0.25%	0.07 - 0.42%
Expected life in years	1.69	0.17 - 2.69
Expected volatility	70%	60 - 80%
Expected dividend yield	0	0
Steps per year	12	12

Warrant Exercises

During the three months ended March 31, 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

During the three months ended March 31, 2012, 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		68,494		—		68,494	$	—	$	140
Cashless exercises		—		31,712		8,021		42		—
		68,494		31,712		76,515	$	42	$	140