In 2018, the Company adopted the 2018 Equity Incentive Plan (“2018 Plan”) which allows for the granting of incentive stock options (“ISO”), non-qualified stock options (“NSO”), stock appreciation rights, restricted stock and restricted stock units to the employees, members of the board of directors and consultants of the Company. In 2018, the Company granted ISOs and NSOs to consultants and directors from this plan. As of December 31, 2020 and June 30, 2021, respectively, 465,116 shares are authorized for issuance and 17,442 shares are available for future grant under the 2018 Plan.

In October 2019, the Company adopted the 2019 Stock Option Plan (“2019 Plan”) which allows for the granting of incentive stock options (“ISO”), non-qualified stock options (“NSO”) to the employees, members of the board of directors and consultants of the Company. In 2019 and during the first seven months of 2020, the Company granted ISOs and NSOs to consultants and directors from the 2019 Plan. As of December 31, 2019, 232,558 shares were authorized for issuance and 75,581 shares were available for future grant under the 2019 Plan. On April 6, 2020 the Company increased the shares authorized for issuance to 348,837 shares total. On February 17, 2021, the Company increased the shares authorized for issuance to 1,767,442 shares total. As of June 30, 2021, 1,296,977 shares were available for future grant under the 2019 Plan.

The following table summarizes activity for stock options under both plans for the six months ended June 30, 2021:

The grant date fair value of options granted during the six months ended June 30, 2021 was $0.7 million.

As of June 30, 2021, the unrecognized compensation cost related to outstanding stock options was $1.2 million, which is expected to be recognized as expense over approximately 2.8 years.

The Company has recorded stock-based compensation expense, allocated by functional cost as follows for the three and six months ended June 30, 2020 and 2021 (in thousands):

Fair Value of Stock Options

The assumptions are based on the following for each of the periods presented:

Expected Term - The expected term is calculated using the simplified method which is used when there is insufficient historical data about exercise patterns and post-vesting employment termination behavior. The simplified method is based on the vesting period and the contractual term for each grant, or for each vesting-tranche for awards with graded vesting. The mid-point between the vesting date and the maximum contractual expiration date is used as the expected term under this method.

Common Stock Fair Value - The fair value of the common stock underlying the Company’s stock options was estimated at each grant date and was determined on a periodic basis and based either on transactions with third parties in which common stock was sold for cash or with the assistance of an independent third-party valuation expert. The assumptions underlying these valuations represented management’s best estimates, which involved inherent uncertainties and the application of significant levels of management judgment.

Volatility - The expected volatility being used is derived from the historical stock volatilities of a representative industry peer group of comparable publicly listed companies over a period approximately equal to the expected term of the options.

Risk-free Interest Rate - The risk-free interest rate is based on median U.S. Treasury zero coupon issues with remaining terms similar to the expected term on the options.

Expected Dividend - The Company has never declared nor paid any cash dividends and does not plan to pay cash dividends in the foreseeable future, and therefore, used an expected dividend yield of zero.

The following averaged assumptions were used to calculate the fair value of awards granted to employees, directors and non-employees for the year ended December 31, 2020 and for the six months ended June 30, 2020 and 2021: