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2. Stock Plans
The following table summarizes option activity:
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Weighted |
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Weighted |
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Average |
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Average |
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Remaining |
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Aggregate |
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Exercise |
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Option |
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Intrinsic |
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Options (in |
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Price per |
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Term |
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Value |
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thousands) |
|
share |
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(in years) |
|
(in thousands) |
Outstanding at December 31, 2020 |
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28 |
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$ |
242.70 |
|
6.35 |
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$ |
— |
Granted |
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670 |
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4.02 |
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Forfeited or expired |
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(6) |
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|
137.74 |
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Outstanding at September 30, 2021 |
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692 |
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$ |
12.46 |
|
9.23 |
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$ |
— |
Exercisable at September 30, 2021 |
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415 |
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$ |
18.08 |
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9.15 |
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$ |
— |
No options to purchase common stock were granted during the three-month period ended September 30, 2021.
The following table summarizes the stock-based compensation expense recorded for awards under our stock option plans (in thousands):
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Three Months Ended |
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Nine Months Ended |
(in thousands) |
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September 30, |
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September 30, |
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2021 |
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2020 |
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2021 |
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2020 |
Research and development |
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$ |
325 |
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$ |
— |
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$ |
659 |
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$ |
— |
Selling, general and administrative |
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|
330 |
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9 |
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|
691 |
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4 |
Total stock-based compensation |
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$ |
655 |
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$ |
9 |
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$ |
1,350 |
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$ |
4 |
We use the Black-Scholes-Merton option-pricing model with the following assumptions to estimate the fair value of our stock options:
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Three Months Ended |
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Nine Months Ended |
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September 30, |
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September 30, |
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2021 |
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2020 |
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2021 |
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2020 |
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Weighted-average risk-free interest rate |
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— |
% |
0.3 |
% |
0.5 |
% |
0.4 |
% |
Expected dividend payments |
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— |
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— |
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— |
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— |
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Expected holding period (years) 1 |
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— |
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5.7 |
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5.5 |
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5.8 |
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Weighted-average volatility factor 2 |
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— |
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1.07 |
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1.14 |
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1.04 |
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Estimated forfeiture rates for options granted 3 |
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— |
% |
24 |
% |
30 |
% |
27 |
% |
| (1) |
Expected holding period is based on historical experience of similar awards, giving consideration to the contractual terms of the stock-based awards, vesting schedules and the expectations of future employee behavior. |
| (2) |
Weighted average volatility is based on the historical volatility of our common stock. |
| (3) |
Estimated forfeiture rates are based on historical data. |
As of September 30, 2021, there was approximately $0.6 million of total unrecognized compensation expense related to non-vested stock options. This expense is expected to be recognized over a weighted-average period of approximately 1.3 years.
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