We have issued warrants related to various transactions in previous years; a summary of warrant transactions follows for the year ended December 31, 2013. The aggregate intrinsic value is based on the closing price of $2.06 on December 31, 2013.
| Shares Underlying Warrants | Weighted-Average Exercise Price | Weighted-Average Remaining Contractual Term (in years) | Aggregate Intrinsic Value (In-The-Money) |
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| Outstanding and exercisable at December 31, 2012 | 6 | $ | 20.20 | – | $ | – | ||||||||||
| Outstanding and exercisable at December 31, 2013 | – | $ | – | – | $ | – | ||||||||||