Stock-Based Compensation (Tables)
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12 Months Ended |
Dec. 31, 2017 |
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| Disclosure of Compensation Related Costs, Share-based Payments [Abstract] |
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| Summary of Stock Option Activity |
Stock-based compensation has been recognized in operating results as follows: | | | | | | | | | | Years ended December 31, | | 2017 | | 2016 | In cost of revenue | $ | 83,713 |
| | $ | 122,301 |
| In research and development expenses | 1,026,497 |
| | 2,420,696 |
| In selling and marketing expense | 676,635 |
| | 2,111,366 |
| In general and administrative expenses | 2,350,962 |
| | 2,910,156 |
| Benefit from restructuring | (125,222 | ) | | (60,203 | ) | Total stock-based compensation | $ | 4,012,585 |
| | $ | 7,504,316 |
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| Estimated Fair Value of Stock Options - Assumptions |
The estimated fair value of stock option awards was determined on the date of grant using the Black-Scholes option valuation model with the following assumptions during the years indicated below: | | | | | | Years ended December 31, | | 2017 | | 2016 | Risk-free interest rate | 1.82% - 2.03% | | 0.93% - 1.89% | Dividend yield | 0% | | 0% | Expected volatility (range) | 86% - 117% | | 80% - 134% | Expected volatility (weighted-average) | 87% | | 103% | Expected term (in years) | 5.3 years | | 5.5 years |
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| Stock-Based Compensation Recognized |
A summary of stock option activity and of changes in stock options outstanding is presented below: | | | | | | | | | | | | | | | Number of Options | | Weighted-Average Exercise Price Per Share | | Intrinsic Value | | Weighted-Average Remaining Contractual Life | Balance outstanding, December 31, 2015 | 6,948,630 |
| | $ | 5.45 |
| | $ | 5,903,466 |
| | 7.8 years | Granted | 3,246,250 |
| | $ | 5.02 |
| | |
| | | Exercised | (1,335,271 | ) | | $ | 3.81 |
| | | | | Forfeited | (3,330,981 | ) | | $ | 5.63 |
| | |
| | | Balance outstanding, December 31, 2016 | 5,528,628 |
| | $ | 5.49 |
| | $ | — |
| | 7.7 years | Granted | 1,059,242 |
| | $ | 0.82 |
| | |
| | | Forfeited | (2,079,938 | ) | | $ | 6.24 |
| | |
| | | Expired | (17,457 | ) | | $ | 4.74 |
| | | | | Balance outstanding, December 31, 2017 | 4,490,475 |
| | $ | 4.04 |
| | $ | — |
| | 7.1 years | Vested and exercisable, December 31, 2017 | 2,745,350 |
| | $ | 4.66 |
| | $ | — |
| | 6.0 years |
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| Summary of Restricted Stock Unit Activity |
A summary of the RSU activity is presented below: | | | | | | | | | | | | | Number of Shares | | Weighted Average Grant Date Fair Value Per Share | | Intrinsic
Value | Non-vested RSU outstanding, December 31, 2015 | — |
| | $ | — |
| | $ | — |
| Granted | 402,000 |
| | $ | 4.06 |
| | | Vested | (95,000 | ) | | $ | 4.27 |
| | | Forfeited | (35,000 | ) | | $ | 3.99 |
| | | Non-vested RSU outstanding, December 31, 2016 | 272,000 |
| | $ | 3.99 |
| | $ | 571,200 |
| Granted | 2,249,242 |
| | $ | 1.59 |
| | | Vested | (372,487 | ) | | $ | 3.47 |
| | | Forfeited | (874,453 | ) | | $ | 1.75 |
| | | Non-vested RSU outstanding, December 31, 2017 | 1,274,302 |
| | $ | 1.43 |
| | $ | 391,848 |
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