Note 8 - Share-based Compensation

3 Months Ended

Mar. 31, 2023

Notes to Financial Statements

Share-Based Payment Arrangement [Text Block]

(8) Share-Based Compensation

The share-based compensation expense is recorded in research and development, and selling, general and administrative expenses based on the employee's or non-employee’s respective function. No share-based compensation was capitalized during the periods presented. Share-based compensation expense for the three months ended March 31, 2023 and 2022 was recorded as follows (in thousands):

	Three months ended
	March 31,
	2023		2022
Research and development	$	139	$	127
Selling, general and administrative		139		192
Total share-based compensation	$	278	$	319

The following table summarizes the activity of stock options and related information:

	Options outstanding
	Number of shares			Weighted average exercise price		Weighted average remaining contractual term (years)		Aggregate intrinsic value (in thousands)
Balance, December 31, 2022		2,182,708		$	4.04		7.5	$	343
Stock options exercised		(199	)		1.49
Stock options forfeited		(14,059	)		2.77
Balance, March 31, 2023		2,168,450		$	4.05		7.3	$	256
Exercisable, March 31, 2023		1,241,371		$	5.27		6.3	$	49

Unrecognized share-based compensation for employee and nonemployee options granted through March 31, 2023 is approximately $1.8 million to be recognized over a remaining weighted average service period of 2.2 years.

Share-Based Compensation (RSUs)

The following summarizes the activity of non-vested RSUs:

				Weighted
				average
				grant date
	Number of			fair value
	shares			per share
Balance, December 31, 2022		21,526		$	4.33
RSUs released		(18,792	)		4.34
Balance, March 31, 2023		2,734		$	4.26

RSUs vested and settled are converted into the Company’s common stock on a one-for-one basis. RSUs are generally subject to forfeiture if employment terminates prior to the release of vesting restrictions. The related compensation expense, which is based on the grant date fair value of our common stock multiplied by the number of units granted, is recognized ratably over the period during which the vesting restrictions lapse. Unrecognized share-based compensation for employee and nonemployee RSUs granted through March 31, 2023 is approximately $1,000 to be recognized over a remaining weighted average service period of 0.1 years.