Stock Based Compensation (Tables)
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6 Months Ended |
Jun. 30, 2019 |
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| Share-based Payment Arrangement, Noncash Expense [Abstract] |
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| Schedule of stock-based compensation expense |
The amount of stock-based compensation expense recognized for the three and six months ended June 30, 2019 and 2018 was as follows:
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Three Months Ended June 30, |
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Six Months Ended June 30, |
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2019 |
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2018 |
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2019 |
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2018 |
Research and development |
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$ |
120,709 |
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$ |
20,379 |
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$ |
178,085 |
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$ |
31,876 |
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General and administrative |
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196,211 |
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549,199 |
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665,336 |
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756,581 |
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Sales and marketing |
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209,789 |
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38,853 |
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279,981 |
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62,798 |
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Total stock-based compensation |
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$ |
526,709 |
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$ |
608,431 |
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$ |
1,123,402 |
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$ |
851,255 |
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| Summary of option activity |
A summary of option activity for the six months ended June 30, 2019 is as follows:
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Options Outstanding |
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Number of shares |
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Weighted average exercise price per share |
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Weighted average grant date fair value of options |
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Weighted average remaining contractual term (in years) |
Balance at December 31, 2018 |
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3,746,597 |
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$ |
4.16 |
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7.8 |
Granted |
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2,381,627 |
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$ |
5.96 |
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$ |
7,691,720 |
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Exercised |
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(74,902 |
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$ |
3.44 |
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Forfeited |
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(796,063 |
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$ |
5.12 |
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$ |
2,325,463 |
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Expired |
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(80,712 |
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$ |
7.95 |
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$ |
279,812 |
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Balance at June 30, 2019 |
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5,176,547 |
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$ |
4.79 |
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8.3 |
Exercisable at June 30, 2019 |
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2,321,047 |
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$ |
4.38 |
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7.0 |
The Company has granted awards that contain market-based vesting conditions. The following table summarizes the Company's market-based option activity for the six months ended June 30, 2019:
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Options Outstanding |
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Number of shares |
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Weighted average exercise price per share |
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Weighted average remaining contractual term (in years) |
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Aggregate intrinsic value (1) |
Balance at December 31, 2018 |
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500,000 |
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$ |
4.24 |
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9.2 |
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Granted |
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300,000 |
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$ |
4.98 |
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Exercised |
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— |
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Forfeited |
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(500,000 |
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$ |
4.24 |
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Balance at June 30, 2019 |
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300,000 |
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$ |
4.98 |
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9.9 |
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$ |
138,000 |
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Exercisable at June 30, 2019 |
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— |
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(1) The aggregate intrinsic value in the above table represents the total pre-tax amount that a participant would receive if the option had been exercised on the last day of the respective fiscal period. Options with a market value less than its exercise value are not included in the intrinsic value amount.
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| Schedule of fair value assumptions for options |
The following table shows the assumptions used to compute stock-based compensation expense for stock options granted to employees and members of the board of directors under the Black-Scholes valuation model and the assumptions used to compute stock-based compensation expense for market-based stock options grants under a Monte Carlo simulation for the six months ended June 30, 2019:
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Service-based options |
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Expected dividend yield |
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—% |
Expected volatility |
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55% |
Expected life (in years) |
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5.0 - 6.25 |
Risk-free interest rate |
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1.76 - 2.59% |
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Market-based options |
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Expected dividend yield |
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—% |
Expected volatility |
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60% |
Expected life (in years) |
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10 |
Risk-free interest rate |
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2.32% |
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| Nonvested Restricted Stock Shares Activity |
The following table summarizes the Company's RSU activity for six months ended June 30, 2019:
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RSUs Outstanding |
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Number of shares |
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Weighted average grant date fair value |
Unvested RSUs at December 31, 2018 |
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445,000 |
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$ |
4.27 |
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Granted |
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295,000 |
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$ |
4.98 |
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Vested |
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(161,250 |
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$ |
4.49 |
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Forfeited |
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(300,000 |
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$ |
4.24 |
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Unvested RSUs at June 30, 2019 |
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278,750 |
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