Note 8 - Share-based Compensation

6 Months Ended

Jun. 30, 2022

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 and six months ended June 30, 2022 and 2021 was recorded as follows (in thousands):

	Three months ended				Six months ended
	June 30,				June 30,
	2022		2021		2022		2021
Research and development	$	130	$	211	$	257	$	417
Selling, general and administrative		174		173		366		383
Total share-based compensation	$	304	$	384	$	623	$	800

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, 2021		1,649,686		$	5.00		7.6	$	—
Stock options granted		504,949			1.53
Stock options exercised		—
Stock options forfeited		(90,688	)		3.68
Stock options expired		(3,111	)		9.55
Balance, June 30, 2022		2,060,836		$	4.20		7.9	$	—
Exercisable, June 30, 2022		955,545		$	5.99		6.5	$	—

Unrecognized share-based compensation for employee and nonemployee options granted through June 30, 2022 is approximately $2.5 million to be recognized over a remaining weighted average service period of 2.8 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, 2021		200,271		$	4.13
RSUs granted		269,204			1.49
RSUs released		(311,929	)		2.74
RSUs forfeited		(87,718	)		1.49
Balance, June 30, 2022		69,828		$	3.44

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. Of the 69,828 RSUs outstanding on June 30, 2022, 67,094 RSUs are vested and have not been settled and 2,734 have not yet vested. The related compensation expense, which is based on the grant date fair value of the Company’s 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 June 30, 2022 is approximately $55,000 to be recognized over a remaining weighted average service period of 0.2 years.