Total stock-based compensation was $4,244 and $2,662 for the three months ended March 31, 2022 and 2021, respectively. As of March 31, 2022, there was $1,626 of unearned compensation expense related to restricted stock awards, which will be recognized over the remaining weighed average requisite service period of 21 months. As of March 31, 2022, there was $2,063 of unearned compensation related to time-vested stock options, which will be recognized over the remaining requisite service period of 29 months.

During 2020 and 2021, the Company granted 1,139,464 and 1,735,500 cash settled stock appreciation rights to certain employees. Each stock appreciation right represents the right to receive a payment measured by the increase in the fair market value of one share of the Company’s stock from the date of grant of the stock appreciation right to the date of exercise of the stock appreciation right. The cash settled stock appreciation rights vest ratably over three years and have a contractual life of 10 years. Cash settled stock appreciation rights are classified as liabilities Vesting of the 2021 cash settled stock appreciation rights was contingent upon the achievement of a thirty-day trailing average fair market value of a share of the Company’s common stock of 133.3% ($3.17) or more of the exercise price per share ($2.38). When vesting of an award of stock-based compensation is dependent upon the attainment of a target stock price, the award is considered to be subject to a market condition. . During the first quarter of 2021, the market condition for the 2021 cash settled stock appreciation rights was met. The Company measures the fair value of unvested cash settled stock appreciation rights using the Black-Scholes option valuation model and remeasures the fair value of the award each reporting period until the award is vested. Once vested the Company immediately recognizes compensation cost for any changes in fair value of cash settled stock appreciation rights until settlement. Fair value of vested cash settled stock appreciation rights represents the fair market value of one share of the Company’s stock on the measurement date less the exercise price per share. Compensation cost for cash settled stock appreciation rights is trued up each reporting period for changes in fair value pro-rated for the portion of the requisite service period rendered.

The estimated fair value of the cash settled stock appreciation rights as of March 31, 2022 was $6,163. Stock-based compensation for cash settled stock appreciation rights was $3,759 and $2,553 for the three months ended March 31, 2022 and 2021, respectively.

The fair value of unvested cash settled stock appreciation rights as of March 31, 2022 was estimated using the Black-Scholes option valuation model with the following assumptions:


				Expected	Risk Free
			Expected	Dividend	Interest	Fair Value
Grant Year	Grant Date	Expected Life	Volatility	Yield	Rate	Per Award

2020	1/24/2020	4.3 years	83.63%	0.00%	2.39%	$	4.92
2020	9/14/2020	4.7 years	81.13%	0.00%	2.41%	$	4.79
2020	11/30/2020	4.9 years	80.14%	0.00%	2.42%	$	4.62
2021	1/5/2021	5.0 years	79.52%	0.00%	2.11%	$	4.70