Total stock-based compensation expense under the 2019 Plan was $6.5 million and $6.9 million for the three months ended March 31, 2023 and 2022, respectively. The total unrecognized compensation expense related to unvested stock option grants as of March 31, 2023 was $30.5 million, with a weighted average remaining vesting period of 2.0 years. Total unrecognized compensation expense related to unvested restricted stock unit (“RSU”) grants as of March 31, 2023 was $23.5 million, with a weighted average remaining vesting period of 3.1 years.

A summary of stock option activity under the 2019 Plan for the three months ended March 31, 2023 is as follows:


	Options Outstanding			Weighted- Average Exercise Price		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2022		20,861,760		$	6.05	$	—
Options Granted		—			—
Options Canceled		(653,505	)		6.45
Options Exercised		—			—
Outstanding at March 31, 2023		20,208,255		$	6.04	$	—
Vested and Expected to Vest at March 31, 2023		20,208,255		$	6.04	$	—

A summary of RSU activity under the 2019 Plan for the three months ended March 31, 2023 is as follows:


	Number of Shares			Weighted- Average Grant Date Fair Value Per Share
Outstanding at December 31, 2022		8,284,498		$	3.73
RSUs Granted		—			—
RSUs Released		—			—
RSUs Canceled		(83,900	)		4.44
Outstanding at March 31, 2023		8,200,598		$	3.72

On March 15, 2023, the Board approved the suspension of any issuance, vesting, and payments related to the awards under the Company’s 2020 Employee Stock Purchase Plan and 2019 Plan effective as of the Petition Date. The Company determined that there are no incremental compensation costs recognized as a result of this suspension for the three months ended March 31, 2023.

For Scilex Holding, total stock-based compensation recorded as operating expenses was $3.7 million and $1.4 million for the three months ended March 31, 2023 and 2022, respectively. The total unrecognized compensation cost related to unvested employee and director stock option grants as of March 31, 2023 was $53.0 million and the weighted average period over which these grants are expected to vest is 3.6 years.

Total stock-based compensation recorded as operating expense for the Company’s 2020 Employee Stock Purchase Plan was not material for the three months ended March 31, 2023, as compared to $0.3 million for the three months ended March 31, 2022.

Total stock-based compensation recorded as operating expense for the 10-year CEO performance award that was granted to the Company’s chief executive officer in 2020 and tied solely to the Company achieving market capitalization milestones (the “CEO Performance Award”) was $8.2 million during the three months ended March 31, 2023. As of March 31, 2023, the Company had approximately $37.9 million of total unrecognized stock-based compensation expense remaining under the CEO Performance Award.