Note 11 - Stock-based Compensation

3 Months Ended

Mar. 31, 2024

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 March 31, 2024, as well as activity, including grants to non-employees, for the three months ended March 31, 2024:

	Number of Shares			Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value (Millions)
Outstanding at December 31, 2023		10,444,679		$	3.20		4.80
Granted		5,552,790			0.26
Cancelled		(36,406	)		10.24
Outstanding at March 31, 2024		15,961,063		$	2.16		5.37	$	-
Vested or expected to vest at March 31, 2024		14,795,731		$	2.30		5.27	$	-
Exercisable at March 31, 2024		7,862,867		$	3.97		4.25	$	-

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

	Three Months Ended March 31,
	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%
Weighted average grant date fair value		$0.22				$0.60

Restricted Stock Units

The following table summarizes information about restricted stock units outstanding as of March 31, 2024, as well as activity, including performance restricted stock units, granted, vested and forfeited, for the three months ended March 31, 2024:

	Number of Shares			Weighted-Average Grant Date Fair Value
Unvested at December 31, 2023		12,326,177		$	0.81
Granted		14,647,450		$	0.26
Vested		(4,655,843	)	$	0.97
Forfeited		(1,358,970	)	$	0.67
Unvested at March 31, 2024		20,958,814		$	0.40

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 months ended March 31, 2024 and 2023:

	Three Months Ended March 31,
	2024		2023
	(in thousands)
Stock options	$	425	$	665
Restricted stock units		956		859
Performance restricted stock units		364		392
	$	1,745	$	1,916

As of March 31, 2024, the unrecognized stock-based compensation expense related to stock options was approximately $2.4 million, which is expected to be recognized over a weighted average period of 2.3 years. As of March 31, 2024, the unrecognized stock-based compensation expense related to unvested restricted stock units and performance restricted stock units was approximately $6.8 million, which is expected to be recognized over a weighted average period of 1.8 years.