8. Stock-Based Compensation

2014 Plan

The Company operates an equity-based compensation plan (the “2014 Plan”). The 2014 Plan provides for the granting of stock options (incentive and nonqualified), restricted stock or other stock-based awards to employees, officers, directors, consultants, and advisors. As of June 30, 2022, 829,339 shares of common stock were authorized to be awarded and 146,735 shares were available for awards.

Stock-based compensation expense is presented in the same expense line items as cash compensation paid and for the three and six months ended June 30 are as follows:

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Stock Options

The Company grants time-based stock options which generally vest one-third of the underlying shares on the one-year anniversary of the grant date and the remainder ratably over a 24-month period. The fair value of time-based stock options is determined using the Black-Scholes Option Pricing Model, with such value recognized as expense over the service period, which is typically 3 years, net of actual forfeitures. A summary of the Company’s assumptions used in determining the fair value of the stock options granted during the six months ended June 30, 2022 and 2021 is shown in the following table.

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The weighted-average grant date fair value of options granted during the six months ended June 30, 2022 and 2021 was $0.68 and $6.12, respectively. The expected term of the options granted is based on management estimate. Expected volatility is based on the historical volatility of the Company’s peers common stock. The risk-free interest rate is determined based upon a constant U.S. Treasury security rate with a contractual life that approximates the expected term of the option. Unamortized compensation expense related to the options amounted to $0.473 million as of June 30, 2022 and is expected to be recognized over a weighted average period of approximately 2.48 years.

Following is a summary of stock option activity for the six months ended June 30, 2022:

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The stock options outstanding and exercisable as of June 30, 2022 had no aggregate intrinsic value. The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying options and the market price of the Company’s common stock for options that had exercise prices lower than $0.47, the closing price of the Company’s stock on June 30, 2022.

Restricted Stock Units

There were no grants of time-based restricted stock units during the three and six months ended June 30, 2022. Restricted stock options compensation expense is recognized over the vesting period, which is typically one-third of the underlying shares on the one-year anniversary of the grant date and the remainder ratably over a 24-month period. Unamortized expense is nominal. The following is a summary of restricted stock activity for the six months ended June 30, 2022:

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Employee Stock Purchase Plan

The Company has a non-qualified Employee Stock Purchase Plan (ESPP), which provides for the issuance of shares of the Company’s common stock to eligible employees of the Company that elect to participate in the plan and purchase shares of common stock through payroll deductions at a discounted price. Six month offering periods are made at the Board’s discretion. The ESPP provides for 11,371 aggregate shares of the Company’s common stock for participants to purchase. As of June 30, 2022, the remaining 7,806 shares are reserved for future offerings.