9. Equity Incentive Plan

In 2005, the Company approved the 2005 Equity Incentive Plan (the “2005 Plan”). The 2005 Plan provides for the granting of options, restricted stock or other stock-based awards to employees, officers, directors, consultants and advisors. During 2010, the maximum number of shares of Common Stock that may be issued pursuant to the 2005 Plan was increased to 59,414 shares. The Board of Directors (the “Board”) is responsible for administration of the 2005 Plan. The Company’s Board determines the term of each option, the option exercise price, the number of shares for which each option is granted and the rate at which each option is exercisable. Incentive stock options may be granted to any officer or employee at an exercise price per share of not less than the fair value per common share on the date of the grant (not less than 110% of fair value in the case of holders of more than 10% of the Company’s voting stock) and with a term not to exceed ten years from the date of the grant (five years for incentive stock options granted to holders of more than 10% of the Company’s voting stock). Nonqualified stock options may be granted to any officer, employee, consultant or director at an exercise price per share of not less than the par value per share. Following adoption of the 2014 Equity Incentive Plan (the “2014 Plan”), no further grants were made under the 2005 Plan. General terms of the 2014 Plan remain the same as that of the 2005 Plan.

The Company’s Board adopted the 2014 Plan and the Employee Stock Purchase Plan (the “ESPP”) and the Company’s Stockholders approved the 2014 Plan and the ESPP Plan in February 2015. As of June 30, 2021, the maximum number of shares of Common Stock that may be issued pursuant to the 2014 Plan and the ESPP was 806,005 and 11,371 shares, respectively.

In January 2021, the number of shares of common stock issuable under the 2014 Plan automatically increased by 23,333 shares pursuant to the terms of the 2014 Plan. Additionally, in June 2021, the number of shares of common stock issuable under the 2014 Plan was increased by 200,000 shares, as approved by the Company’s Stockholders. These additional shares are included in the total of 806,005 shares issuable under the 2014 Plan.

9. Equity Incentive Plan - (continued)

The following is a summary of stock option activity for the six months ended June 30, 2021 and 2020:

​

​

During the six months ended June 30, 2021 and 2020, the Board approved the grant of options to purchase 150,365 and 93,165 shares of Common Stock, respectively. All option grants were pursuant to the 2014 Plan. In general, options granted under the 2014 Plan vest with respect to one-third of the underlying shares on the one-year anniversary of the grant date and the remainder ratably over a 24-month period.

For the six months ended June 30, 2021 and 2020, the fair value of each option grant has been estimated on the date of grant using the Black-Scholes Option Pricing Model with the following weighted-average assumptions:

​

​

Using the Black-Scholes Option Pricing Model, the estimated weighted average fair value of an option to purchase one share of common stock granted during the six months ended June 30, 2021 and 2020 was $6.12 and $6.26, respectively.

9. Equity Incentive Plan - (continued)

The following is a summary of restricted stock activity for the six months ended June 30, 2021 and 2020:

​

​

During the six months ended June 30, 2021, 2,051 shares of restricted stock, which had not vested, were forfeited and returned to the Company. During the six months ended June 30, 2021 and 2020, the Board approved the grant of 0 and 49,000  restricted shares of Common Stock, respectively. All grants of restricted shares were pursuant to the 2014 Plan. These vest with respect to 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 total stock-based compensation expense for employees and non-employees is included in the accompanying Condensed Consolidated Statements of Operations and as follows:

​

​

The fair value of options granted for the six months ended June 30, 2021 and 2020 was $0.909 million and $0.580 million, respectively. As of June 30, 2021 and 2020, there was $1.117 million and $1.161 million of total unrecognized compensation expense related to unvested stock-based compensation arrangements granted, which cost is expected to be recognized over a weighted-average period of 2.26 and 2.28 years, respectively. The aggregate intrinsic value of stock options outstanding and exercisable at June 30, 2021 and 2020 was $0.

At June 30, 2021, there were 264,337 shares available for grant under the 2014 Plan and 7,806 shares available under the Company’s ESPP.