As disclosed in Note 17, on October 6, 2017, the Company issued restricted stock awards totaling 3,900,000 shares of its common stock to 16 employees and awarded nonqualified stock options to purchase an aggregate of 360,000 shares of its common stock at a strike price $1.98 per share to two employees. Shares of restricted stock have the same dividend and voting rights as common stock while options do not. All awards were issued at the fair value of the underlying shares at the grant date.

During the year ended March 31, 2018, stock options covering a total of 360,000 shares of common stock were granted. No options were granted during the three and six month periods ended September 30, 2018. Total compensation expense related to options granted was $54 for the three months ended September 30, 2018 and $0 for the three months ended September 30, 2017. Total compensation expense related to options granted for the six months periods ended September 30, 2018 and 2017 was $108 and $0, respectively. As of September 30, 2018, there was total remaining compensation expense of $435 related to stock options, which will be recorded over a weighted average period of approximately 2.02 years. No options were exercisable or exercised during the three and six month periods ended September 30, 2018 and 2017.

The Company has determined fair value of stock options using the Black-Scholes option valuation model based on the following key assumptions:

During the year ended March 31, 2018, a total of 3,900,000 shares of common stock were awarded. During the three and six months ended September 30, 2018 and 2017, no shares of common stock were awarded. The compensation expense related to restricted stock grants was $793 during the three months ended September 30, 2018, and $0 during the three ended September 30, 2017. Total compensation expense related to restricted stock grants was $1,578 and $0 during the six months ended September 30, 2018 and 2017, respectively. As of September 30, 2018, there was $5,091 of total unrecognized compensation cost related to nonvested shares of common stock granted. The cost is expected to be recognized over a weighted average period of 1.71 years.

Stock-based compensation expense for the cost of the awards granted is based on the grant-date fair value. For stock option awards, the fair value is estimated at the date of grant using the Black-Scholes option-pricing model. This model requires the input of highly subjective assumptions, changes to which can materially affect the fair value estimate. Additionally, there may be other factors that would otherwise have a significant effect on the value of employee stock options granted but are not considered by the model. Accordingly, while management believes that the Black-Scholes option-pricing model provides a reasonable estimate of fair value, the model does not necessarily provide the best single measure of fair value for the Company's employee stock options.

The following is a summary of stock option activity for the six months ended September 30, 2018:

The table below summarizes the activity for the Company's restricted stock outstanding during the six months ended September 30, 2018: