Note 11 - Stock-based Compensation

6 Months Ended

Jun. 30, 2023

Notes to Financial Statements

Share-Based Payment Arrangement [Text Block]

11. Stock-Based Compensation

Incentive Compensation Plan Information

On June 6, 2023, at the 2023 Annual Meeting of Stockholders, the Company’s stockholders voted to approve an amendment and restatement of the Company’s Incentive Compensation Plan (“the Plan”) to increase the number of shares reserved for issuance under the Plan by 22,000,000 shares. As a result of this amendment, shares authorized for issuance under the Plan increased to 54,072,307 shares.

Stock Options

The following table summarizes options outstanding as of June 30, 2023, as well as activity, including grants to non-employees, for the six months ended June 30, 2023:

	Number of Shares			Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value (Millions)
Outstanding at December 31, 2022		7,584,967		$	4.22		5.31
Granted		3,047,615		$	0.71
Exercised		(13,300	)	$	0.38
Cancelled		(16,762	)	$	27.89
Forfeited		(106	)	$	15.86
Outstanding at June 30, 2023		10,602,414		$	3.18		5.34	$	0.2
Vested or expected to vest at June 30, 2023		10,028,804		$	3.32		5.29	$	0.2
Exercisable at June 30, 2023		5,411,149		$	5.31		4.58	$	0.2

The fair value of options granted were estimated using the Black-Scholes-Merton option pricing model based on the assumptions in the table below:

	Six Months Ended June 30,
	2023				2022
Expected volatility		124%	-	130%		128%	-	133%
Risk-free interest rate		3.53%	-	4.14%		1.25%	-	2.98%
Expected life (in years)		3.8	-	4.5		4.3	-	4.5
Expected dividend yield			0%				0%
Weighted average grant date fair value	$			0.59	$			0.61

Restricted Stock Units

The following table summarizes information about restricted stock units outstanding as of June 30, 2023, as well as activity, including performance restricted stock units, for the six months ended June 30, 2023:

	Number of Shares			Weighted- Average Grant Date Fair Value
Outstanding at December 31, 2022		8,483,491		$	1.04
Granted		8,163,060		$	0.72
Vested		(3,355,753	)	$	1.13
Forfeited		(352,110	)	$	0.82
Outstanding at June 30, 2023		12,938,688		$	0.82

Performance-Based Restricted Stock Units

In 2023 and 2022, the Company granted performance-based restricted stock units. In particular, the number of shares earnable under the 2023 and 2022 awards is based on achieving certain operational targets by December 31, 2023 and October 1, 2023, respectively. These operational targets have been achieved for the awards granted in 2022, therefore the 2022 performance-based restricted stock units are fully earned and remain subject to three-year time-based vesting requirements. The Company has not yet achieved the operational targets required for the awards granted in 2023.

Stock-Based Compensation Expense

The following table summarizes non-cash stock-based compensation expense by award type for the three and six months ended June 30, 2023 and 2022:

	Three Months Ended June 30,				Six Months Ended June 30,
	2023		2022		2023		2022
	(in thousands)				(in thousands)
Stock options	$	591	$	924	$	1,256	$	1,901
Restricted stock units		977		822		1,836		1,707
Performance restricted stock units		410		337		802		720
	$	1,978	$	2,083	$	3,894	$	4,328

As of June 30, 2023, the Company had future stock-based compensation expense of approximately $2.5 million related to unvested stock options, which is expected to be recognized over an estimated weighted-average period of approximately 1.9 years. As of June 30, 2023, the unrecognized stock-based compensation expense related to unvested restricted stock units and performance restricted stock units was approximately $6.5 million, which is expected to be recognized over a weighted average period of approximately 1.6 years.