| Option award activity |
The following is a summary of option award activity under the Emergent Plans:
| | 2006 Plan | | | 2004 Plan | | | | | | | Number of Shares | | | Weighted-Average Exercise Price | | | Number of Shares | | | Weighted-Average Exercise Price | | | Aggregate Intrinsic Value | | Outstanding at December 31, 2012 | | | 3,549,842 | | | $ | 17.08 | | | | 53,156 | | | $ | 8.86 | | | $ | 4,801,378 | | Exercisable at December 31, 2012 | | | 2,144,732 | | | $ | 16.25 | | | | 53,156 | | | $ | 8.86 | | | $ | 4,476,830 | | Granted | | | 993,544 | | | | 15.21 | | | | - | | | | - | | | | | | Exercised | | | (481,549 | ) | | | 12.61 | | | | - | | | | - | | | | | | Forfeited | | | (419,742 | ) | | | 18.34 | | | | - | | | | - | | | | | | Outstanding at December 31, 2013 | | | 3,642,095 | | | $ | 17.01 | | | | 53,156 | | | $ | 8.86 | | | $ | 23,148,738 | | Exercisable at December 31, 2013 | | | 2,074,772 | | | $ | 17.44 | | | | 53,156 | | | $ | 8.86 | | | $ | 12,685,394 | | Options expected to vest at December 31, 2013 | | | 1,171,171 | | | $ | 16.44 | | | | - | | | $ | - | | | $ | 7,820,256 | |
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| Restricted stock units activity |
The following is a summary of restricted stock unit award activity under the 2006 Plan:
| | Number of Shares | | | Weighted-Average Grant Price | | | Aggregate Intrinsic Value | | Outstanding at December 31, 2012 | | | 715,276 | | | $ | 18.41 | | | $ | 11,473,027 | | Granted | | | 496,771 | | | | 15.21 | | | | | | Vested | | | (337,498 | ) | | | 14.91 | | | | | | Forfeited | | | (80,873 | ) | | | 16.72 | | | | | | Outstanding at December 31, 2013 | | | 793,676 | | | $ | 16.52 | | | $ | 18,246,611 | |
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| Allocated stock-based compensation expense |
Stock-based compensation expense from the 2006 Plan was recorded in the following financial statement line items:
| Years Ended | | | December 31, | | (in thousands) | 2013 | | 2012 | | 2011 | | Cost of product sales | | $ | 575 | | | $ | 513 | | | $ | 466 | | Research and development | | | 3,283 | | | | 3,451 | | | | 3,203 | | General and administrative | | | 7,252 | | | | 7,151 | | | | 7,070 | | Total stock-based compensation expense | | $ | 11,110 | | | $ | 11,115 | | | $ | 10,739 | |
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