Note 15 - Stock-based Compensation

12 Months Ended

Dec. 31, 2022

Notes to Financial Statements

Share-Based Payment Arrangement [Text Block]

15. Stock-Based Compensation

The Company recorded total stock-based compensation expense for stock options, stock awards and the Amended ESPP as follows (in thousands):

		December 31, 2022				December 31, 2021
Cost of goods sold		$	—			$	85
Research and development			570				813
Selling, general and administrative			2,069				2,932
Discontinued operations			250				779
Total		$	2,889			$	4,609

The following table summarizes restricted stock unit activity under the Company’s Equity Incentive Plans:

						Weighted
		Number of				*Average*
		*Restricted*				Grant Date
		Stock Units				Fair Value
Restricted stock units outstanding, January 1, 2021			69,890			$	35.75
Granted			57,448				33.65
Vested			(29,338	)			37.75
Forfeited			(9,289	)			31.56
Restricted stock units outstanding, December 31, 2021			88,711			$	34.16
Granted			58,502				7.75
Vested			(44,744	)			35.46
Forfeited			(19,691	)			25.00
Restricted stock units outstanding, December 31, 2022			82,778			$	16.97

The following table summarizes stock option activity under the Company’s Equity Incentive Plans:

		Number of Stock Options Outstanding				Weighted- Average Exercise Price				Weighted- Average Remaining Contractual Life (Years)				Aggregate Intrinsic Value
														(in thousands)
December 31, 2021			714,085			$	59.79
Granted			117,022				7.75
Forfeited			(35,645	)			26.46
Expired			(69,839	)			60.42
Exercised			—				—
December 31, 2022			725,623			$	52.98				5.3			$	—
Vested and exercisable options—December 31, 2022			515,933			$	65.76				3.9			$	—
Vested and expected to vest—December 31, 2022			725,623			$	52.80				5.3			$	—

As of December 31, 2022, there were 342,827 shares available for future grant under the 2020 EIP.

Additional information regarding the Company’s stock options outstanding and vested and exercisable as of December 31, 2022 is summarized below:

				Options Outstanding												Options Vested and Exercisable
Exercise Prices				Number of Stock Options Outstanding				Weighted-Average Remaining Contractual Life (Years)				Weighted-Average Exercise Price per Share				Shares Subject to Stock Options				Weighted-Average Exercise Price per Share
$4.62	-	$8.03			88,096				9.2			$	7.54				—			$	—
$8.36	-	$12.54			19,046				9.1			$	8.43				—			$	—
$14.40	-	$21.60			20,941				6.9			$	16.93				13,643			$	16.84
$22.40	-	$33.60			11,700				8.1			$	28.62				10,774			$	28.58
$34.40	-	$51.60			311,695				6.0			$	41.16				217,425			$	42.75
$52.00	-	$78.00			168,275				3.5			$	62.66				168,221			$	62.66
$78.40	-	$117.60			62,756				1.0			$	97.95				62,756			$	97.95
$132.00	-	$198.00			20,520				1.6			$	133.16				20,520			$	133.16
$204.40	-	$306.60			22,594				1.0			$	206.96				22,594			$	206.96
					725,623				5.3			$	52.98				515,933			$	65.76

The weighted average grant-date fair value of options granted during the years ended December 31, 2022 and 2021 was $5.80 and $24.74 per share, respectively. As of December 31, 2022, total stock-based compensation expense related to unvested options to be recognized in future periods was $1.8 million which is expected to be recognized over a weighted-average period of 1.8 years. The grant date fair value of shares vested during the years ended December 31, 2022 and 2021 was $1.7 million and $2.4 million, respectively. The total intrinsic value of options exercised during the years ended December 31, 2021 and 2020 was $0 and $5.7 thousand, respectively.

On March 3, 2021, the Company granted 1.27 million performance-based stock options to certain of its executive officers, which are included in the stock option tables and associated disclosures above. The awards were granted under the 2020 EIP with an exercise price of $1.88 per share, the closing sales price as reported on the Nasdaq on the date of grant. The performance-based stock options are eligible to vest subject to the satisfaction of the service-based vesting requirements and attainment of share price target goals, a market-based condition. No performance-based stock options vested during the years ended December 31, 2022 and 2021.

The Company uses the Monte Carlo Simulation model to evaluate the derived service period and fair value of awards with market conditions, including assumptions of historical volatility and risk-free interest rate commensurate with the vesting term.

The Company used the following assumptions to calculate the fair value of each performance-based stock option:

		Year Ended December 31,
		2022				2021
Derived service period (in years)			—			2.3	–	2.6
Risk-free interest rate			—			1.5%
Expected volatility			—			90%
Expected dividend rate			—			0%

The Company used the following assumptions to calculate the fair value of each time-based stock option:

		Year Ended December 31,
		2022					2021
Expected term (in years)		6.3					6.0	-	6.2
Risk-free interest rate		1.6%	-	3.0%			0.9%	-	1.3%
Expected volatility		88%					90%
Expected dividend rate		0%					0%