Stock-Based Compensation (Tables)
|
9 Months Ended |
Sep. 30, 2018 |
Summary of Stock-based Compensation Expense Recognized |
During the three and nine months ended September 30, 2018 and 2017, the Company recognized the following stock-based compensation expense (in thousands):
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|
Three Months Ended September 30, |
|
|
Nine Months Ended September 30, |
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|
|
2018 |
|
|
2017 |
|
|
2018 |
|
|
2017 |
|
Stock-based compensation expense by type of award: |
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|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Stock options |
|
$ |
447 |
|
|
$ |
154 |
|
|
$ |
1,018 |
|
|
$ |
529 |
|
Restricted stock and restricted stock units |
|
|
79 |
|
|
|
180 |
|
|
|
403 |
|
|
|
521 |
|
Employee stock purchase plan |
|
|
224 |
|
|
|
10 |
|
|
|
570 |
|
|
|
38 |
|
Total stock-based compensation expense included
in expenses |
|
$ |
750 |
|
|
$ |
344 |
|
|
$ |
1,991 |
|
|
$ |
1,088 |
|
Stock-based compensation expense by line item: |
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|
|
|
|
|
|
|
|
|
|
|
|
|
|
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Research and development expenses |
|
$ |
325 |
|
|
$ |
85 |
|
|
$ |
720 |
|
|
$ |
302 |
|
General and administrative expenses |
|
|
425 |
|
|
|
259 |
|
|
|
1,271 |
|
|
|
786 |
|
Total stock-based compensation expense included
in expenses |
|
$ |
750 |
|
|
$ |
344 |
|
|
$ |
1,991 |
|
|
$ |
1,088 |
|
|
Schedule of Unrecognized Stock-based Compensation Expense, Net of Estimated Forfeitures, by Type of Award and Weighted-average Recognition Period |
The following table sets forth the Company’s unrecognized stock-based compensation expense, net of estimated forfeitures, by type of award and the weighted-average period over which that expense is expected to be recognized (in thousands, except for years):
|
|
As of September 30, 2018 |
|
|
|
Unrecognized
Expense,
Net of
Estimated
Forfeitures |
|
|
Weighted-
average
Recognition
Period
(in years) |
|
|
|
|
|
|
|
|
|
|
Type of award: |
|
|
|
|
|
|
|
|
Stock options |
|
$ |
2,378 |
|
|
|
2.59 |
|
Restricted stock and restricted stock units |
|
$ |
541 |
|
|
|
2.15 |
|
|
Summary of Stock Option Activity |
The following table summarizes stock option activity during the nine months ended September 30, 2018:
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|
Shares Subject to Stock Options |
|
|
Weighted-
Average
Exercise
Price |
|
|
Weighted-
Average
Remaining
Contractual
Term (in years) |
|
|
Aggregate Intrinsic Value |
|
Options outstanding at December 31, 2017 |
|
|
1,575,864 |
|
|
$ |
2.68 |
|
|
|
|
|
|
|
|
|
Granted |
|
|
628,500 |
|
|
$ |
5.89 |
|
|
|
|
|
|
|
|
|
Exercised |
|
|
(171,567 |
) |
|
$ |
2.31 |
|
|
|
|
|
|
|
1,332,000 |
|
Cancelled |
|
|
(18,750 |
) |
|
$ |
1.91 |
|
|
|
|
|
|
|
|
|
Options outstanding at September 30, 2018 |
|
|
2,014,047 |
|
|
$ |
3.72 |
|
|
|
8.29 |
|
|
|
27,584,000 |
|
Options exercisable at September 30, 2018 |
|
|
807,091 |
|
|
$ |
3.99 |
|
|
|
7.60 |
|
|
|
10,836,000 |
|
|
Schedule of Weighted Average Assumptions using Black-Scholes Option Pricing Model |
the fair value of each employee option grant during the nine months ended September 30, 2018 was estimated on the date of grant using the Black-Scholes option pricing model with the following weighted average assumptions:
|
|
Nine Months Ended September 30, 2018 |
|
Expected volatility |
|
|
80.86 |
% |
Expected term (in years) |
|
|
6.00 |
|
Risk-free interest rate |
|
|
2.55 |
% |
Expected dividend yield |
|
|
0 |
% |
|
Restricted stock [Member] |
|
Summary of Stock Activity |
The following table is a summary of restricted stock activity during the nine months ended September 30, 2018:
|
|
Shares of Restricted Stock |
|
|
Weighted-
Average
Grant Date
Fair Value |
|
Unvested at December 31, 2017 |
|
|
245,096 |
|
|
$ |
2.53 |
|
Granted |
|
|
— |
|
|
$ |
— |
|
Vested |
|
|
(62,001 |
) |
|
$ |
9.49 |
|
Forfeited |
|
|
— |
|
|
$ |
— |
|
Unvested at September 30, 2018 |
|
|
183,095 |
|
|
$ |
0.17 |
|
|
Restricted stock units [Member] |
|
Summary of Stock Activity |
The following table summarizes restricted stock unit activity during the nine months ended September 30, 2018:
|
|
Shares Subject to Restricted Stock Units |
|
|
Weighted-
Average
Grant Date
Value |
|
Unvested at December 31, 2017 |
|
|
46,250 |
|
|
$ |
5.50 |
|
Granted |
|
|
105,000 |
|
|
$ |
5.34 |
|
Vested |
|
|
(13,125 |
) |
|
$ |
8.78 |
|
Forfeited |
|
|
— |
|
|
$ |
— |
|
Unvested September 30, 2018 |
|
|
138,125 |
|
|
$ |
5.07 |
|
|