FAIR VALUE MEASUREMENT AND FINANCIAL INSTRUMENTS (Tables)

6 Months Ended

Jun. 30, 2013

FAIR VALUE MEASUREMENT AND FINANCIAL INSTRUMENTS

Schedule of assets and liabilities that are measured at fair value on a recurring basis

There were no transfers in or out of Level 1, Level 2 or Level 3 measurements for the periods presented (in thousands):

	JUNE 30, 2013		LEVEL 1		LEVEL 2		LEVEL 3
Assets
Cash equivalents	$	7,407		—	$	7,407	$	—
Marketable securities		10,516		—		10,516		—
Restricted cash equivalents and marketable securities		363		—		363		—
	$	18,286	$	—	$	18,286	$	—
Liability
Warrant liability		12,208		—		—		12,208
	$	12,208	$	—	$	—	$	12,208

	DECEMBER 31, 2012		LEVEL 1		LEVEL 2		LEVEL 3
Assets
Cash equivalents	$	15,580	$	—	$	15,580	$	—
Marketable securities		18,580	$	—		18,580		—
Restricted cash equivalents and marketable securities		374		—		374		—
	$	34,534	$	—	$	34,534	$	—
Liability
Warrant liability		—		—		—		—
	$	—	$	—	$	—	$	—

Schedule of reconciliation of the warrant liability measured at fair value using significant unobservable inputs (Level 3)

The following table presents a reconciliation of the warrant liability measured at fair value using significant unobservable inputs (Level 3) from January 1, 2013 to June 30, 2013 (in thousands):

	THREE MONTHS ENDED JUNE 30,				SIX MONTHS ENDED JUNE 30,
	2013		2012		2013			2012
Liabilities:
Balance at beginning of period:	$	11,823	$	—	$	16,195		$	—
Change in fair value of warrant liability included in other (expense)/income		385		—		(3,987	)		—
Balance at end of period:	$	12,208	$	—	$	12,208		$	—

Schedule of assumption used to calculate fair value of the warrant liability

	JANUARY 1, 2013						JUNE 30, 2013
	2011 Warrants			2012 Warrants			2011 Warrants			2012 Warrants
Risk-free interest rate		1.2	%		1.4	%		1.2	%		1.4	%
Volatility		107.5	%		116.3	%		126.4	%		116.6	%
Dividend Yield		0	%		0	%		0	%		0	%
Expected life in years		3.3			4.9			2.8			4.4