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2. Stock Plans
The following table summarizes our 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) |
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(in thousands) |
Outstanding at December 31, 2021 |
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682 |
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$ |
12.53 |
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8.98 |
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$ |
— |
Granted |
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310 |
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1.18 |
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Forfeited or expired |
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(2) |
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531.11 |
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Outstanding at March 31, 2022 |
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990 |
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$ |
8.28 |
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9.07 |
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$ |
— |
Exercisable at March 31, 2022 |
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511 |
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$ |
14.01 |
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8.71 |
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$ |
— |
Approximately 310,000 options to purchase common shares were granted during the three-month period ended March 31, 2022.
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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March 31, |
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2022 |
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2021 |
Research and development |
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$ |
123 |
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$ |
120 |
Selling, general and administrative |
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103 |
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128 |
Total stock-based compensation expense |
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$ |
226 |
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$ |
248 |
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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March 31, |
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2022 |
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2021 |
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Weighted-average risk-free interest rate |
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1.47 |
% |
0.54 |
% |
Expected dividend payments |
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— |
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— |
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Expected holding period (years)(1) |
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5.4 |
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5.5 |
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Weighted-average volatility factor (2) |
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113.2 |
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113.9 |
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Estimated forfeiture rates for options granted (3) |
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5.14 |
% |
29.6 |
% |
| (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 March 31, 2022, 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 1.0 years.
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