Equity Incentive Plans

In the first quarter of 2016, the Company adopted the 2016 Equity Incentive Plan. In the fourth quarter of 2018, the Company adopted the 2018 Equity Incentive Plan. The following table contains information about both plans as of December 31, 2020:

Stock Options

The following table summarizes the Company’s stock option activity and related information for the year ended December 31, 2020 and 2019:

The aggregate intrinsic value is calculated as the difference between the Company’s closing stock price of $0.15 on December 31, 2020 and the exercise price of options, multiplied by the number of options. As of December 31, 2020, there was $1.24 million total unrecognized stock-based compensation. Such costs are expected to be recognized over a weighted-average period of approximately 2.75 years. The weighted average fair value of awards granted was $0.08 and $0.53 during 2020 and 2019, respectively.

The Company recognizes compensation expense for stock option awards on a straight-line basis over the applicable service period of the award. The service period is generally the vesting period. The following weighted-average assumptions were used to calculate stock-based compensation:

The Company does not have sufficient historical information to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior. Hence, the Company uses the “simplified method” described in Staff Accounting Bulletin 107 to estimate the expected term of share option grants.

The expected stock price volatility assumption was determined by examining the historical volatilities for the Company’s common stock. The Company will continue to analyze the historical stock price volatility and expected term assumptions as more historical data for the Company’s common stock becomes available.

The risk-free interest rate assumption is based on the U.S. treasury instruments whose term was consistent with the expected term of the Company’s stock options.

The expected dividend assumption is based on the Company’s history and expectation of dividend payouts. The Company has never paid dividends on its common stock and does not anticipate paying dividends on its common stock in the foreseeable future. Accordingly, the Company has assumed no dividend yield for purposes of estimating the fair value of the Company stock-based compensation.

Stock-Based Compensation Expense

The following table sets forth the total stock-based compensation expense resulting from stock options and restricted grants of common stock to employees, directors and non-employee consultants in the consolidated statement of operations which are included in selling, general and administrative expenses: