Warrants

6 Months Ended

Jun. 30, 2012

Warrants [Abstract]

Warrants

5. WARRANTS

Warrants issued in connection with the Company’s December 2007, January 2009, and August 2009 common stock offerings are classified as liabilities opposed to equity due to their settlement terms which requires settlement in registered shares. These warrants are non-cash liabilities and the Company is not required to expend any cash to settle these liabilities. All other warrants issued by the Company were recorded as additional paid-in-capital and no further adjustments are made.

The fair value of the warrants classified as liabilities was recorded on the balance sheet at issuance and are adjusted to fair value at each financial reporting period, with changes in the fair value recorded as a gain or loss in the statement of operations. The fair value is determined using the Black-Scholes option-pricing model, which requires the use of significant judgment and estimates for the inputs used in the model. The following reflects the weighted-average assumptions for each of the periods indicated:

	Three and Six Months Ended June 30,
	2012			2011
Risk-free interest rate		0.2%-0.3	%		0.5%-1.3	%
Expected dividend yield		0	%		0	%
Expected lives		0.5-2.2 years			1.5-3.4 years
Expected volatility		71.8%-90.5	%		55.3%-88.5	%
Shares underlying warrants classified as liabilities		4,824,827			4,824,827
Market value of stock at beginning of year	$	4.50		$	12.72
Market value of stock at end of period	$	3.78		$	8.58

A reconciliation of the change in value of the Company’s warrant liability for the three and six months ended June 30, 2012 is as follows:

	Three Months Ended June 30, 2012			Six Months Ended June 30, 2012
	(in thousands)			(in thousands)
Balance at beginning of period	$	16,372		$	5,446
Increase (Decrease) in value of warrants		(13,488	)		(2,562	)
Reclassification to shareholders’ equity upon exercise of warrants		—			—
Balance at June 30, 2012	$	2,884		$	2,884

The following table summarizes information about warrants outstanding at June 30, 2012.

Exercise Price		Outstanding Warrants at June 30, 2012		Weighted Average Remaining Contractual Life (Years)	Exercisable Warrants
$	0.0018		2,778	No expiration date		2,778
	1.0074		39,705	0.4		39,705
	6.84		167	No expiration date		167
	6.96		2,354,034	2.1		2,354,034
	8.70		11,024	1.6		11,024
	10.68		1,568,385	2.2		1,568,385
	14.70		891,385	0.5		891,385
			4,867,478			4,867,478