VALERO ENERGY CORP/TX | 2013 | FY | 3

For the years ended December 31, 2013, 2012, and 2011, activity in the number of shares of common stock and treasury stock was as follows (in millions):
 
Common
Stock
 
Treasury
Stock
Balance as of December 31, 2010
673

 
(105
)
Transactions in connection with
   stock-based compensation plans:
 
 
 
Stock issuances
—

 
5

Stock repurchases
—

 
(17
)
Balance as of December 31, 2011
673

 
(117
)
Transactions in connection with
   stock-based compensation plans:
 
 
 
Stock issuances
—

 
6

Stock repurchases
—

 
(6
)
Stock repurchases under buyback program
—

 
(4
)
Balance as of December 31, 2012
673

 
(121
)
Transactions in connection with
   stock-based compensation plans:
 
 
 
Stock issuances
—

 
6

Stock repurchases
—

 
(6
)
Stock repurchases under buyback program
—

 
(17
)
Balance as of December 31, 2013
673

 
(138
)

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