Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2013

Stock-Based Compensation

Schedule of weighted average assumptions used to estimate fair value of each service-based stock option grant

	Nine Months Ended  September 30,
Service-Based Stock Options	2012	2013
Expected dividend rate	0%	0%
Expected stock price volatility	72.9 – 74.9%	74.0 – 87.9%
Risk-free interest rate	0.9 - 1.5%	0.1 - 2.1%
Expected life (years)	6.0 - 6.3	5.0 - 6.3

Summary of activity for service-based stock options

Service-Based Stock Options	Options		Weighted  Average  Exercise Price		Weighted Average  Remaining  Contractual Term  (Years)	Aggregate  Intrinsic Value
Outstanding at December 31, 2012	9,987,468		$	2.38	7.5	$	—
Granted	1,515,000		$	1.07
Exercised	—		$	—		$	—
Expired	(2,787,259	)	$	2.64
Forfeited	(2,275,186	)	$	2.27
Outstanding at September 30, 2013	6,440,023		$	1.99	7.6	$	—
Exercisable at September 30, 2013	2,982,001		$	2.35	6.1	$	—