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Common Stock (Tables) | 12 Months Ended
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Dec. 31, 2015
Common Stock. |
Schedule of Common Stock reserved for future issuance |
|  | As of December 31, |
|  | 2015 |  | 2014 |
Conversion of Series A Preferred Stock |  |  | — |  |  | 5,356,996 |
Conversion of Series B Preferred Stock |  |  | — |  |  | 2,655,992 |
Warrants for the purchase of Preferred Stock |  |  | — |  |  | 12,283 |
Warrants for the purchase of Common Stock |  |  | 59,405 |  |  | 34,839 |
Options to purchase Common Stock |  |  | 2,557,456 |  |  | 1,385,341 |
Employee Stock Purchase Plan |  |  | 182,352 |  |  | — |
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Total |  |  | 2,799,213 |  |  | 9,445,451 |
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