STOCK-BASED COMPENSATION (Tables)

6 Months Ended

Jun. 30, 2024

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,
	2024					2023				2024					2023
	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		5,100		$	72.37		54,575	$	66.82		321,478		$	67.63		1,084,924		$	72.50
Restricted stock units		54,905	(1)	$	138.91		33,752	$	121.27		1,216,890	(1)	$	129.05		1,109,663	(2)	$	153.89

(1) Included in restricted stock units (“RSUs”) for the three and six months ended June 30, 2024 are 8,860 and 97,460 shares with performance conditions (“March 2024 PSUs”), respectively, which are related to the achievement of certain financial performance goals and regulatory approval of certain of the Company's product candidates. The expanded regulatory approval of ELEVIDYS in June 2024 resulted in the cliff-vesting of 44,300 of the 97,460 shares of the March 2024 PSUs during the three and six months ended June 30, 2024. As of June 30, 2024, none of the performance conditions for the remaining 53,160 shares were probable of being achieved. Stock options and the remaining RSUs granted during the three and six months ended June 30, 2024 have only service-based criteria and vest over four years.

(2) Included in the RSUs for the six months ended June 30, 2023 are 502,225 shares with performance conditions (the “March 2023 PSUs”), which are related to regulatory approval of ELEVIDYS and achievement of a certain financial performance target, both of which were achieved in 2023. Vesting of the March 2023 PSUs is contingent on the fulfillment of remaining service conditions.

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 and by function included within the unaudited condensed consolidated statements of comprehensive income (loss):

		For the Three Months Ended June 30,					For the Six Months Ended June 30,
		2024			2023		2024			2023
	(in thousands)
Stock options		$	15,515		$	21,135	$	31,796		$	44,965
Restricted stock units			37,808			25,037		65,335			41,177
Employee stock purchase plan			2,331			1,205		3,728			2,485
Subtotal		$	55,654		$	47,377	$	100,859		$	88,627
Capitalized stock-based compensation costs*			(5,172	)		—		(9,685	)		—
Total stock-based compensation expense included in expenses		$	50,482		$	47,377	$	91,174		$	88,627
Research and development			19,806			21,577		36,079			37,990
Selling, general and administrative			30,676			25,800		55,095			50,637
Total stock-based compensation expense included in expenses		$	50,482		$	47,377	$	91,174		$	88,627

*Prior to the six months ended June 30, 2024, capitalized stock-based compensation costs were not material.