Stock-Based Awards (Tables)

12 Months Ended

Dec. 31, 2023

Stock-Based Awards [Abstract]

Weighted-Average Assumptions for Stock Options

The weighted average assumptions that the Company used in the Black-Scholes pricing model to determine the fair value of the stock options granted to employees, non-employees and directors were as follows:

	For the Years Ended December 31,
	2023			2022			2021
Risk-free interest rate		4.00	%		2.19	%		0.83	%
Expected term (in years)		5.82			5.09			5.84
Expected volatility		73.32	%		64.12	%		69.27	%
Expected dividend yield		0.00	%		0.00	%		0.00	%
Exercise price	$	20.24		$	18.56		$	51.20
Fair value of common stock	$	20.24		$	18.56		$	51.20

Stock Option Activity

The following table summarizes stock option activity for the years ended December 31, 2023 and 2022:

				Weighted		Weighted
				Average		Average		Aggregate
	Number of			Exercise		Contractual		Intrinsic
	Shares			Price		Term (Yrs)		Value
Outstanding as of December 31, 2021		11,143,761		$	14.51		5.95	$	128,817
Conversion of Renovacor awards		367,852			4.63		0.40
Granted		2,305,910			13.94		5.53
Exercised		(66,887	)		9.43				514
Cancelled or forfeited		(611,766	)		32.55
Outstanding as of December 31, 2022		13,138,870		$	14.52		5.46	$	118,767
Granted		2,370,862			20.24		8.76
Exercised		(223,145	)		10.00				2,318
Cancelled or forfeited		(422,591	)		29.82
Outstanding as of December 31, 2023		14,863,996		$	15.07		5.16	$	250,602
Options vested and exercisable as of December 31, 2023		11,657,122		$	13.57		4.13	$	217,871
Options unvested as of December 31, 2023		3,206,874		$	20.50		8.91	$	32,731

RSU Activity

The following table summarizes the RSU activity for the years ended December 31, 2023 and 2022:

				Weighted Average
	Number of			Grant Date
	Shares			Fair Value
Unvested as of December 31, 2021		23,500		$	30.61
Conversion of Renovacor awards		28,798			0.49
Granted		1,047,301			15.91
Vested		(38,966	)		23.15
Forfeited		(67,759	)		15.94
Unvested as of December 31, 2022		992,874		$	16.49
Granted		1,018,322			19.67
Vested (1)		(408,119	)		16.61
Forfeited		(112,720	)		17.92
Unvested as of December 31, 2023		1,490,357		$	18.53

(1) Common stock issued is net of 120 shares related to taxes.

Stock-Based Compensation Expense by Award Type

Stock-based compensation expense recognized by award type is as follows:

	For the Years Ended December 31,
	2023		2022		2021
Stock options	$	29,091	$	27,620	$	28,811
Restricted stock units		10,315		3,389		426
Total stock-based compensation expense	$	39,406	$	31,009	$	29,237

Stock-Based Compensation Expense

Stock-based compensation expense by classification included within the consolidated statements of operations and comprehensive loss was as follows:

	For the Years Ended December 31,
	2023		2022		2021
Research and development	$	17,509	$	12,466	$	11,954
General and administrative		21,897		18,543		17,283
Total stock-based compensation expense	$	39,406	$	31,009	$	29,237