Note 11 - Stock-based Compensation

9 Months Ended

Sep. 30, 2021

Notes to Financial Statements

Share-based Payment Arrangement [Text Block]

11. Stock-Based Compensation

Stock-Based Compensation Expense. The Company records stock-based compensation expense during the requisite service period for share-based payment awards granted to employees and non-employees. 

Our stock-based compensation is classified as either an equity award or a liability award in accordance with generally accepted accounting principles. The fair value of an equity-classified award is determined at the grant date and is amortized on a straight-line basis over the vesting life of the award. The fair-value of a liability-classified award is determined on a quarterly basis through the final vesting date and is amortized based on the current fair value of the award and the percentage of vesting period incurred to date.

The following table sets forth the Company’s stock-based compensation expense (in thousands) for the periods indicated:

	Three Months Ended September 30,					Nine Months Ended September 30,
	2021			2020		2021		2020
Equity Classified Awards
Stock options
Research and development	$	188		$	—	$	188	$	—
Selling, general and administrative		598			—		598		—
Restricted stock
Research and development		273			142		519		353
Selling, general and administrative		821			500		1,995		1,122
Total equity classified awards		1,880			642		3,300		1,475
Liability Classified Awards
Restricted stock
Selling, general and administrative		2,368			—		2,368		—
Stock appreciation rights
Research and development		(40	)		16		149		(61	)
Selling, general and administrative		(2	)		16		6		(67	)
Total liability classified awards		2,326			32		2,523		(128	)
Total stock-based compensation	$	4,206		$	674	$	5,823	$	1,347

Stock Option Award Activity. Stock option activity under the Company’s stock incentive plans at September 30, 2021 and changes during the nine months ended September 30, 2021 were as follows:

					Weighted-
					Average
			Weighted-		Remaining
			Average		Contractual	Aggregate
	Number of		Exercise		Term	Intrinsic
	Options		Price (1)		(years)	Value
Options outstanding at December 31, 2020	1,552		$	556.13	5.6	$	—
Granted	4,670,324		$	4.98
Canceled or forfeited	(1,597	)	$	130.67
Exercised	—		$	—
Options outstanding at September 30, 2021	4,670,279		$	5.12	9.9	$	7,750,148
Options exercisable at September 30, 2021	1,515		$	431.34	4.9	$	—
Options vested and expected to vest at September 30, 2021	4,435,359		$	5.12	9.9	$	7,360,181

(1)  Exercise price of options outstanding range from $4.98 to $56,460 as of September 30, 2021.

The following table shows the number of stock options granted under the Company’s stock incentive plans and the assumptions used to determine the fair value of those options using a Black-Scholes option-pricing model during the nine months ended September 30, 2021:

Period Ended	Total Stock Options Granted	Weighted-Average Exercise Price		Weighted-Average Expected Term	Weighted Average Volatility	Weighted-Average Risk-Free Interest Rate	Expected Dividends		Weighted-Average Grant Date Fair Value
September 30, 2021	4,670,324	$	4.98	5.75 years	144%	0.87%	$	0	$	4.57

No stock options were granted under the Company's stock incentive plans during the nine months ended September 30, 2020. 

During the three and nine months ended September 30, 2021, the Company included stock-based compensation costs related to stock option awards of $0.2 million in "Research and development expense" and $0.6 million in "Selling, general and administrative expense" in the Consolidated Statements of Operations, respectively. The Company did not recognize any stock-based compensation expenses related to stock option awards during the three and nine months ended September 30, 2020. 

No stock options vested during the nine months ended September 30, 2021. As of September 30, 2021, the total unrecognized compensation expense, net of estimated forfeitures, relating to stock options was $18.7 million, which is expected to be recognized over the remaining weighted-average period of approximately 2.9 years.

Restricted Stock. Non-vested restricted stock awards at September 30, 2021 and changes during the nine months ended September 30, 2021 were as follows:

			Weighted-
			Average
	Number of		Grant-Date
	Shares		Fair Value
Non-vested at December 31, 2020	4,701,556		$	0.79
Granted	4,807,378		$	5.08
Vested	(2,585,547	)	$	0.99
Canceled or forfeited	(129,149	)	$	0.84
Non-vested at September 30, 2021	6,794,238		$	3.75

The total fair value of restricted stock that vested during the nine months ended September 30, 2021 was $2.6 million. As of September 30, 2021, the total unrecognized compensation expense, net of estimated forfeitures, relating to restricted stock awards was $24.8 million, which is expected to be recognized over the remaining weighted-average period of approximately 2.7 years. As of September 30, 2021, we had recorded a liability of $0.9 million for earned and unvested liability-classified restricted stock awards based on the fair value of our common stock as of September 30, 2021.