Share-Based Compensation

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Share-based Compensation

The Company utilizes share-based compensation in the form of stock options, restricted stock, and restricted stock units. The following table summarizes the components of share-based compensation expense for the years ended December 31, 2023 and 2022 ($ in thousands):


	Year Ended December 31,
	2023		2022
Research and development	$	540	$	776
General and administrative	1,498		1,860

Total share-based compensation expense	$	2,038	$	2,636

The Company modified the exercise period of approximately 186,600 shares of one terminated employee's vested stock options and immediately recognized approximately $258 thousand incremental stock-based compensation during the year ended December 31, 2023.

Total compensation cost related to unvested awards not yet recognized and the weighted-average periods over which the awards are expected to be recognized at December 31, 2023 were as follows ($ in thousands):


	Stock Options		Restricted Stock Units		Restricted Stock
Unrecognized compensation cost	$	186	$	76	$	391
Expected weighted-average period in years of compensation cost to be recognized	1.70		1.55		1.53

Total fair value of shares vested and the weighted average estimated fair values of shares granted for the years ended December 31, 2023 and 2022 were as follows ($ in thousands):


	Stock Options
	Year Ended December 31,
	2023		2022
Total fair value of shares vested	$	1,033	$	1,045
Weighted average estimated fair value of shares granted	2.09		1.23

Valuation Assumptions

The fair value of stock options at the date of grant was estimated using the Black-Scholes option pricing model. The expected volatility is based upon historical volatility of the Company’s stock. The expected term for the options is based upon observation of actual time elapsed between date of grant and exercise of options for all employees.

The range of assumptions made in calculating the fair values of stock options was as follows:


	Stock Options
	Year Ended December 31,
	2023	2022
Expected term - minimum (in years)	3	6
Expected term - maximum (in years)	6	6
Expected volatility - minimum	74%	76%
Expected volatility - maximum	77%	78%
Weighted Average volatility	75%	76%
Expected dividend yield	—	—
Risk-free interest rate - minimum	3.63%	1.62%
Risk-free interest rate - maximum	4.68%	2.90%