2016 & 2018 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. On June 20, 2019, the Company amended the number of shares reserved for issuance to 15,000,000. The following table contains information about the 2016 and the 2018 Equity Incentive Plans as of June 30, 2019:

Stock Options

The following table summarizes the Companys stock option activity and related information for the three months ended June 30, 2019:

The aggregate intrinsic value is calculated as the difference between the Companys closing stock price of $0.58 on June 30, 2019, and the exercise price of options, multiplied by the number of options. As of June 30, 2019, there was $8.06 million total unrecognized stock-based compensation. Such costs are expected to be recognized over a weighted-average period of approximately 2.75 years.

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 for issuances during the three months ended June 30, 2019:

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 Companys common stock. The Company will continue to analyze the historical stock price volatility and expected term assumptions as more historical data for the Companys 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 Companys stock options.

The expected dividend assumption is based on the Companys 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.

The Company estimates the forfeiture rate at the time of grant and revisions, if necessary, were estimated based on managements expectation through industry knowledge and historical data.

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:

* Excludes adjustments for shares cancelled.