Note 8 - Share-based Compensation

6 Months Ended

Jun. 30, 2021

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, 2021 and 2020 was recorded as follows (in thousands):

	Three months ended				Six months ended
	June 30,				June 30,
	2021		2020		2021		2020
Research and development	$	211	$	318	$	417	$	731
Selling, general and administrative		173		337		383		865
Total share-based compensation	$	384	$	655	$	800	$	1,596

On January 29, 2020 (the repricing date), the Company’s Board of Directors repriced certain previously granted and still outstanding vested and unvested stock option awards held by employees, executives and certain service providers of the Company; as a result, the exercise price was lowered to $5.32 per share. No other terms of the repriced stock options were modified, and the repriced stock options will continue to vest according to their original vesting schedules and will retain their original expiration dates. As a result of the repricing, 515,036 vested and unvested stock options outstanding with original exercise prices ranging from $10.05 to $97.21, were repriced.

The repricing on January 29, 2020 resulted in incremental stock-based compensation expense of $569,000, of which $412,000 related to vested employee stock option awards and was expensed on the repricing date, and $157,000 related to unvested stock option awards is being amortized on a straight-line basis over the approximately three year remaining weighted average vesting period of those awards. 

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, 2020		1,114,306		$	5.89		7.5	$	177.1
Stock options granted		717,935			3.61
Stock options exercised		(1,580	)		2.49
Stock options forfeited		(145,477	)		4.57
Stock options expired		(125	)		5.32
Balance, June 30, 2021		1,685,059		$	5.04		8.0	$	604.3
Exercisable, June 30, 2021		668,537		$	7.13		5.8	$	89.0

Unrecognized share-based compensation for employee and nonemployee options granted through June 30, 2021 is approximately $3.3 million to be recognized over a remaining weighted average service period of 2.9 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, 2020		224,311		$	4.12
RSUs granted		131,375			3.61
RSUs released		(118,472	)		3.73
RSUs forfeited		(36,943	)		3.49
Balance, June 30, 2021		200,271		$	4.13

Unrecognized share-based compensation for employee and nonemployee RSUs granted through June 30, 2021 is $67,000 to be recognized over a remaining weighted average service period of 0.6 years.