Quarterly report pursuant to Section 13 or 15(d)

Stock-based Compensation (Tables)

v2.4.0.8
Stock-based Compensation (Tables)
 6 Months Ended
Jun. 30, 2014
Stock-based Compensation [Abstract]  
Weighted average assumptions
The fair value of the stock options granted was estimated based on the following weighted average assumptions for the three and six months ended June 30, 2014 and 2013:

 
  
Three Months Ended June 30,
    
Six Months Ended June 30,
  
 
  
2014
    
2013
    
2014
    
2013
  
Dividend yield
    
0
%
    
0
%
    
0
%
    
0
%
Expected volatility
    
91
%
    
92
%
    
93
%
    
92
%
Risk-free interest rate
    
1.68
%
    
1.44
%
    
1.71
%
    
0.84
%
Expected term
  
5.6 years
    
5.6 years
    
5.6 years
    
5.6 years
  
Stock option activity
Stock option activity for the six months ended June 30, 2014 was as follows:

 
  
Options
    
Weighted Average Exercise Price Per Share
    
Weighted Average Remaining Contractual Life (in years)
    
Aggregate Intrinsic Value (in thousands)
  
Options outstanding at December 31, 2013
    
7,218,241
    
$
8.42
      
6.75
    
$
18,213
  
Granted
    
1,621,089
      
7.11
                  
Exercised
    
(736,896
)
    
4.32
                  
Forfeited, expired or cancelled
    
(286,255
)
    
19.11
                  
Options outstanding at June 30, 2014
    
7,816,179
    
$
8.14
      
7.00
    
$
7,382
  
Options exercisable at June 30, 2014
    
4,684,553
    
$
10.34
      
5.72
    
$
4,278
  
Unvested RSU activity
Unvested RSU activity for the six months ended June 30, 2014 is summarized below:

 
  
   
Weighted-
  
 
  
Number of
    
Average Grant-
  
 
  
Shares
    
Date Fair Value
  
Unvested balance at December 31, 2013
    
1,738,037
    
$
2.73
  
Granted
    
1,299,164
      
6.47
  
Vested
    
(514,125
)
    
4.11
  
Forfeited
    
(158,286
)
    
3.87
  
Unvested balance at June 30, 2014
    
2,364,790
    
$
4.97
  
Stock-based compensation expense
The following table shows total stock-based compensation expense included in the condensed consolidated statements of comprehensive loss for the three and six months ended June 30, 2014 and 2013 (in thousands):

 
  
Three Months Ended June 30,
    
Six Months Ended June 30,
  
 
  
2014
    
2013
    
2014
    
2013
  
Research and development
  
$
953
    
$
432
    
$
3,359
    
$
1,429
  
Selling, general and administrative
    
1,471
      
667
      
2,989
      
1,290
  
Total stock-based compensation expense
  
$
2,424
    
$
1,099
    
$
6,348
    
$
2,719