Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2014

Computation of Basic and Diluted Net Loss per Share

The following table sets forth the reconciliation of the numerator and denominator used in the computation of basic and diluted net loss per share for the three and nine months ended September 30, 2014 and 2013 (in thousands, except per share amounts):

	Three Months Ended         September 30,				Nine Months Ended         September 30,
	2014		2013		2014		2013
Numerator for Basic and Diluted:
Net loss used for basic calculation	$	(10,759)	$	(20,501)	$	(18,573)	$	(37,477)
Effect of revaluation of warrant liability		(1,738)		0		(14,263)		0
Adjusted net loss used for diluted calculation	$	(12,497)	$	(20,501)	$	(32,836)	$	(37,477)
Denominator:
Basic weighted average number of shares outstanding		75,194		69,791		73,407		66,464
Effect of dilutive potential shares		909		0		2,030		0
Diluted weighted average number of shares outstanding		76,103		69,791		75,437		66,464
Net loss per share:
Basic	$	(0.14)	$	(0.29)	$	(0.25)	$	(0.56)
Diluted	$	(0.16)	$	(0.29)	$	(0.44)	$	(0.56)

Anti-Dilutive Effect of Common Shares

The table below presents shares underlying stock options, employee stock purchase plan rights and restricted stock units that are excluded from the calculation of the weighted average number of shares outstanding used for the calculation of diluted net loss per share. Warrants are excluded from the table below in periods for which the warrants are included in the calculation of diluted net loss per share. These are excluded from the calculation due to their anti-dilutive effect for the three and nine months ended September 30, 2014 and 2013 (shares in thousands):

	Three Months Ended         September 30,				Nine Months Ended         September 30,
	2014		2013		2014		2013
Weighted average number of anti-dilutive potential shares		12,032		16,651		11,737		16,301