STOCK-BASED COMPENSATION (Tables)

6 Months Ended

Jun. 30, 2023

Share-Based Payment Arrangement [Abstract]

Summary of Stock Awards Granted

The following table summarizes the Company’s stock awards granted for each of the periods indicated:

	For the Three Months Ended June 30,								For the Six Months Ended June 30,
	2023				2022				2023				2022
	Grants		Weighted Average Grant Date Fair Value		Grants		Weighted Average Grant Date Fair Value		Grants		Weighted Average Grant Date Fair Value		Grants		Weighted Average Grant Date Fair Value
Stock options		54,575	$	66.82		207,583	$	43.40		1,084,924	$	72.50		1,499,120	$	46.49
Restricted stock units*		33,752	$	121.27		147,075	$	72.99		1,109,663	$	153.89		859,510	$	78.78

*Included in restricted stock units (“RSUs”) for the three and six months ended June 30, 2023 and 2022 are 502,225 and 38,500 shares, respectively, with performance conditions (“PSUs”) which are related to regulatory approval of certain of the Company's product candidates. As a result of the regulatory approval of ELEVIDYS in June 2023, the Compensation Committee of the Company's Board of Directors determined that one of the performance conditions was met, resulting in the recognition of stock-based compensation expense of $7.4 million associated with 394,975 PSUs with performance conditions during the three and six months ended June 30, 2023. Vesting of the 394,975 PSUs with performance conditions achieved is contingent on the fulfillment of remaining service conditions. The remaining expense associated with the 394,975 PSUs with performance conditions achieved is $54.2 million and will be recognized over approximately the next 1.7 years. If the performance milestones are met within the required time frame for the remaining PSUs, the Company may recognize up to $22.4

million of stock-based compensation expense. Stock options and the remaining RSUs granted during the periods presented in the table have only service-based criteria and vest over four years.

Summary of Stock-Based Compensation Expense by Function Included within Condensed Consolidated Statements of Operations and Comprehensive Loss

The following table summarizes stock-based compensation expense by function included within the unaudited condensed consolidated statements of operations and comprehensive loss:

		For the Three Months Ended June 30,				For the Six Months Ended June 30,
		2023		2022		2023		2022
	(in thousands)
Research and development		$	21,577	$	14,467	$	37,990	$	27,535
Selling, general and administrative			25,800		88,425		50,637		104,555
Total stock-based compensation expense		$	47,377	$	102,892	$	88,627	$	132,090

Summary of Stock-Based Compensation Expense by Grant Type Included within Consolidated Statements of Operations and Comprehensive Loss

The following table summarizes stock-based compensation expense by grant type included within the unaudited condensed consolidated statements of operations and comprehensive loss:

		For the Three Months Ended June 30,				For the Six Months Ended June 30,
		2023		2022		2023		2022
	(in thousands)
Stock options		$	21,135	$	89,155	$	44,965	$	105,561
Restricted stock units			25,037		12,378		41,177		23,743
Employee stock purchase plan			1,205		1,359		2,485		2,786
Total stock-based compensation expense		$	47,377	$	102,892	$	88,627	$	132,090