Stock-Based Compensation

6 Months Ended

Jun. 30, 2024

Note 4 - Stock-Based Compensation

Under the fair value recognition provisions of U.S. GAAP for accounting for stock-based compensation the Company measures stock-based compensation expense at the grant date based on the fair value of the award and recognizes the compensation expense over the requisite service period, which is generally the vesting period.

The following table presents the classification of stock-based compensation expense recognized for the periods below:

	Three months ended June 30				Six months ended June 30
(in thousands)	2024		2023		2024		2023
Selling, general and administrative expense	$	115	$	179	$	272	$	351
Research and development expense		—		18		1		27
Total stock-based compensation expense	$	115	$	197	$	273	$	378

During the three months ended June 30, 2024 and 2023, under the 2017 Equity Incentive Plan, and the 2021 Inducement Plan, the Company granted 1 and 267 stock options, respectively, to its directors, officers and employees. During the six months ended June 30, 2024 and 2023, the Company granted 1,264 and 2,937 stock options, respectively, to its directors, officers and employees. Vesting generally occurs over an immediate to 48-month period based on a time-of-service condition. The weighted-average grant date fair value of the stock-options issued during the three months ended June 30, 2024 and 2023 was $8.75 and $103.52 per share, respectively. The weighted-average grant date fair value of the stock options issued during the six months ended June 30, 2024 and 2023 was $24.14 and $258.19 per share, respectively.

The total number of stock options outstanding as of June 30, 2024 and June 30, 2023 was 3,979 and 3,164, respectively.

The weighted-average assumptions used in the Black-Scholes option-pricing model are as follows for the stock options granted during the three and six months ended June 30, 2024 and 2023:

	Three months ended						Six months ended
	June 30						June 30
	2024			2023			2024			2023
Expected volatility		138.70	%		132.13	%		138.70	%		156.35	%
Expected Life of options (years)		5.51			6.08			5.51			6.23
Expected dividend yield		0	%		0	%		0	%		0	%
Risk-free interest rate		3.94	%		3.75	%		3.94	%		4.13	%

During the three months ended June 30, 2024 and 2023, 472 and 32 stock options vested, respectively, and 91 and 79 stock options were expired or forfeited during these periods, respectively. During the six months ended June 30, 2024 and 2023, 1,347 and 60 stock options vested, respectively, and 363 and 84 stock options were expired or forfeited during these periods, respectively. During the three and six months ended June 30, 2024 and 2023, no options were exercised.