A summary of the activity associated with warrants during 2013, 2012 and 2011 is as follows (in thousands):
| Warrants | ||||
|
Balance at December 31, 2011 |
42,676 | |||
|
Retirement of public warrants |
(9,635 | ) | ||
|
|
|
|||
|
Balance at December 31, 2012 and 2013 |
33,041 | |||
|
|
|
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