In accordance with the Company’s 2013 Incentive Plan, stock awards, including stock options and restricted stock, have been granted to certain employees and non-employee directors. Shares of common stock available for distribution to satisfy the grants may consist, in whole or in part, of authorized and unissued shares, treasury shares or shares reacquired by the Company in any manner. Stock-based compensation expense related to stock awards totaled $0.2 million for both of the six-month periods ended June 30, 2021 and 2020.

Stock option awards have been granted with an exercise price equal to the market price of the Company’s common stock on the date of the grant and have vesting periods ranging from one to three years, with 10-year contractual terms.

The Company recognizes the cost of services received in exchange for stock option awards based on the grant date fair value of the award, with compensation expense recognized on a straight-line basis over the award’s vesting period. The fair value of outstanding awards was determined using the Black-Scholes option pricing model based on the assumptions noted in the table below. Expected volatilities are based on historical volatilities of the Company’s common stock. The Company did not grant any stock option awards during the six months ended June 30, 2021.

The following table summarizes the Company’s stock option activity for the periods presented.

	Six Months Ended
	June 30, 2021				June 30, 2020
	Number of Shares		Average Exercise Price		Number of Shares		Average Exercise Price
Options:
Outstanding, beginning of period		421,000	$	9.79		412,800	$	9.72
Granted		—		—		10,200		11.95
Exercised		—		—		666		10.75
Expired		—		—		—		—
Forfeited		—		—		334		10.75
Options outstanding, end of period		421,000	$	9.79		422,000	$	9.77
Options exercisable, end of period		396,095	$	9.74		353,183	$	9.59

The aggregate intrinsic value of stock options outstanding (calculated as the amount by which the market value of underlying stock exceeds the exercise price of the option) was approximately $0.7 million and zero as of June 30, 2021 and 2020, respectively.

During the six months ended June 30, 2021 and 2020, respectively, 37,930 shares and 28,460 shares of restricted stock were granted. The Company recognizes the cost of services received in exchange for restricted stock awards based on the grant date closing price of the stock, with compensation expense recognized on a straight-line basis over the award’s vesting period.