XML 95 R50.htm IDEA: XBRL DOCUMENT  v2.3.0.11
Stock-based compensation plans (Tables)
 12 Months Ended
Mar. 31, 2011
Stock Based Compensation Plans (Tables) [Abstract]  
Weighted-average assumptions, used to determine the fair value of stock acquisition rights granted on the date of grant and used to recognize compensation expense
The fair value of stock acquisition rights granted on the date of grant and used to recognize compensation expense for the fiscal years ended March 31, 2009, 2010 and 2011 was estimated using the Black-Scholes option-pricing model with the following weighted-average assumptions:
 
                         
    Fiscal year ended March 31
    2009   2010   2011
 
Weighted-average assumptions
                       
Risk-free interest rate
    2.07 %     2.08 %     1.60 %
Expected lives
    6.23 years     6.49 years     6.64 years
Expected volatility*
    33.35 %     33.70 %     35.74 %
Expected dividends
    1.29 %     0.99 %     0.83 %
 
  *  Expected volatility was based on the historical volatilities of Sony Corporation’s common stock over the expected life of the stock acquisition rights.
 
Summary of the activities regarding the stock acquisition rights plan during the fiscal year
A summary of the activities regarding the stock acquisition rights plan during the fiscal year ended March 31, 2011 is as follows:
 
                                 
    Fiscal year ended March 31, 2011
        Weighted-
 		  Weighted-
 		  Total
    Number of
 		  average
 		  average
 		  Intrinsic
    Shares   exercise price   remaining life   Value
        Yen   Years   Yen in millions
 
Outstanding at beginning of the fiscal year
    15,214,400       3,743                  
Granted
    2,334,600       2,985                  
Exercised
    (65,200 )     2,653                  
Forfeited or expired
    (472,400 )     3,540                  
                                 
Outstanding at end of the fiscal year
    17,011,400       3,458       6.20       523  
                                 
Exercisable at end of the fiscal year
    12,184,000       3,739       5.10       211  
                                 
Summary of the convertible bond plan
 
A summary of the activities regarding the convertible bond plan during the fiscal year ended March 31, 2011 is as follows:
 
                                 
    Fiscal year ended March 31, 2011
        Weighted-
 		  Weighted-
 		  Total
    Number of
 		  average
 		  average
 		  Intrinsic
    Shares   exercise price   remaining life   Value
        Yen   Years   Yen in millions
 
Outstanding at beginning of the fiscal year
    1,621,500       9,099                  
Expired
    (1,073,000 )     10,208                  
                                 
Outstanding at end of the fiscal year
    548,500       6,931       1.00       —  
                                 
Exercisable at end of the fiscal year
    548,500       6,931       1.00       —