The following table summarizes the outstanding warrants and the corresponding exercise price as of December 31, 2013 and 2012:
| Number of Shares Outstanding December 31, |
Per Share Exercise Price |
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| 2013 | 2012 | |||||||||||
|
October 2007 common stock warrants |
274 | 274 | $ | 1,913.05 | ||||||||
|
April 2012 common stock warrants |
— | 75,974 | 4.08 | |||||||||
|
September 2012 common stock warrants |
— | 8,408 | 5.05 | |||||||||
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Total |
274 | 84,656 | ||||||||||
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