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, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]  
Stock-Based Compensation Expense

Stock-based compensation expense, which consists of the compensation cost for employee stock options and ESPP, and the value of options issued to non-employees for services rendered, was allocated to research and development and general and administrative in the unaudited condensed consolidated statements of operations as follows (in thousands):

 

     Three Months Ended
June 30,		      Six Months Ended
June 30,		  
     2013      2012      2013      2012  

Amortization of stock-based compensation:

            

Research and development

    $ 663       $ 370       $ 1,197       $ 611   

General and administrative

      609         374         1,128         532   
  

 

 

     

 

 

     

 

 

     

 

 

  
   $ 1,272       $ 744       $ 2,325       $ 1,143   
  

 

 

     

 

 

     

 

 

     

 

 

  
Weighted-Average Fair Value Valuation Assumptions

The fair value of employee stock options and employee purchase rights under the Company’s ESPP was estimated using the following weighted-average assumptions for the three and six months ended June 30, 2013 and 2012:

 

     Three Months Ended
June 30,		     Six Months Ended
June 30,		  
     2013     2012     2013     2012  

Employee Stock Options

         

Risk-free interest rate

      0.96 %      1.13 %      1.13 %      1.14 % 

Expected term (in years)

      5.47        5.96        5.97        5.98   

Dividend yield

      —          —          —          —     

Volatility

      102 %      107 %      101 %      107 % 

Weighted-average fair value of stock options granted

    $ 4.28      $ 5.64      $ 4.03      $ 5.03   

 

     Three Months Ended
June 30,		     Six Months Ended
June 30,		  
     2013     2012     2013     2012  

Employee Stock Purchase Plan (ESPP):

         

Risk-free interest rate

      0.20 %      0.20 %      0.20 %      0.20 % 

Expected term (in years)

      1.25        1.25        1.25        1.25   

Dividend yield

      —          —          —          —     

Volatility

      92 %      111 %      92 %      111 % 

Weighted-average fair value of ESPP purchase rights

    $ 2.44      $ 2.04      $ 2.44      $ 2.04   
Stock Option Activity Under Equity Incentive Plan

The following table summarizes stock option activity under the Company’s 2004 Equity Incentive Plan:

 

Options

    Number of
Shares		     Weighted-
Average
Exercise
Price		      Weighted-
Average
Remaining
Contractual
Term		      Aggregate
Intrinsic
Value		  

Outstanding at December 31, 2012

      5,098,972     $ 3.18        —          —    

Granted

      1,618,500     $ 5.10        —          —    

Exercised

      (95,825 )   $ 1.76        —          —    

Forfeitures

      (51,458 )   $ 7.71        —          —    
  

 

 

          

Outstanding at June 30, 2013

      6,570,189     $ 3.64        8.07      $ 13,093,522  
  

 

 

          

Vested and expected to vest June 30, 2013

      6,500,552     $ 3.62        8.06      $ 13,056,277  

Exercisable at June 30, 2013

      2,977,250     $ 2.44        7.08      $ 9,109,942