Note 12 - Stock-based Compensation

6 Months Ended

Jun. 30, 2024

Notes to Financial Statements

Share-Based Payment Arrangement [Text Block]

12. 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, 2024, as well as activity, including grants to non-employees, for the six months ended June 30, 2024:

	Number of Shares			Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value (thousands)
Outstanding at December 31, 2023		10,444,679		$	3.20		4.80
Granted		5,552,790			0.26
Cancelled		(110,980	)		15.61
Outstanding at June 30, 2024		15,886,489		$	2.07		5.14	$	389
Vested or expected to vest at June 30, 2024		14,894,960		$	2.18		5.06	$	334
Exercisable at June 30, 2024		7,919,713		$	3.74		4.04	$	-

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,
	2024					2023
Expected volatility		126%	-	127%		124%	-	126%
Risk-free interest rate		4.06%	-	4.07%		3.73%	-	4.14%
Expected life (in years)		4.3	-	4.5		4.3	-	4.5
Expected dividend yield		0			%		0		%

Restricted Stock Units

The following table summarizes information about restricted stock units outstanding as of June 30, 2024, as well as activity, including performance restricted stock units, granted, vested and forfeited, for the six months ended June 30, 2024:

	Number of Shares			Weighted-Average Grant Date Fair Value
Unvested at December 31, 2023		12,326,177		$	0.81
Granted		14,953,974		$	0.26
Vested		(5,455,413	)	$	0.91
Forfeited		(1,396,905	)	$	0.66
Unvested at June 30, 2024		20,427,833		$	0.39

Vesting of Performance-Based Restricted Stock Units

In 2024 and 2023, the Company granted performance-based restricted stock units (“PRSUs”). The number of shares earnable under the 2023 awards were based on achieving certain operational targets by December 31, 2023 (for the PRSUs granted in 2023). In February 2024, the Board determined that the operational targets for PRSU awards granted in 2023 were 50% achieved and as a result, the 2023 PRSUs were 50% earned and remain subject to three-year time-based vesting requirements. The other 50% of the 2023 PRSUs were forfeited.

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, 2024 and 2023:

	Three Months Ended June 30,				Six Months Ended June 30,
	2024		2023		2024		2023
	(in thousands)
Stock options	$	341	$	591	$	766	$	1,256
Restricted stock units		844		977		1,800		1,836
Performance restricted stock units		343		410		707		802
	$	1,528	$	1,978	$	3,273	$	3,894

As of June 30, 2024, the unrecognized stock-based compensation expense related to stock options was approximately $2.1 million, which is expected to be recognized over a weighted average period of 2.1 years. As of June 30, 2024, the unrecognized stock-based compensation expense related to unvested restricted stock units and performance restricted stock units was approximately $5.6 million, which is expected to be recognized over a weighted average period of 1.7 years.