STOCK-BASED COMPENSATION (Tables)

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Summary of allocated expense

The following table summarizes ESPP expense incurred under the 2016 Employee Stock Purchase Plan and included in the consolidated statements of operations:

(in thousands)	Years Ended December 31,
	2023		2022		2021
Selling, general, and administrative	$	360	$	222	$	87
Cost of sales	60		50		15
Research and development	47		41		21
	$	467	$	313	$	123

The following table summarizes stock-based compensation expense incurred for stock options, restricted stock awards, performance-based restricted stock units, and Inducement Grants and included in the consolidated statements of operations:

(in thousands)	Years Ended December 31,
	2023		2022		2021
Selling, general, and administrative	$	18,676	$	13,094	$	9,818
Research and development	863		710		543
Cost of sales	646		482		5
	$	20,185	$	14,286	$	10,366

Valuation assumptions

For 2023, 2022, and 2021, the fair value of each option grant was estimated using the Black-Scholes option-pricing model, using the following assumptions:

	Years Ended December 31,
	2023	2022	2021
Expected option life (years)	6.25	5.50 - 6.25	5.50 - 6.25
Risk-free interest rate	4.1%	1.71% - 2.83%	0.68% - 1.39%
Expected stock price volatility	49.0%	48.4% - 50.0%	48.2% - 49.5%
Dividend yield	—	—	—

Summary of stock option and restricted stock activity

A summary of stock option activity under the 2022 Plan and Inducement Grants during the years ended December 31, 2023, 2022, and 2021 is presented below:

(in thousands, except per share and remaining term data)	Option Shares	Weighted Average Exercise Price		Fair Value		Weighted Average Remaining Term (years)	Aggregate Intrinsic Value
Outstanding December 31, 2020	936	$	48.44			7.1	$	372
Granted	168	33.09		$	15.71
Exercised	(42)	40.25					552
Forfeited	(19)	59.84
Expired	(55)	55.59
Outstanding December 31, 2021	988	$	45.56			6.6	$	6,786
Granted	36	34.52		$	16.82
Exercised	(23)	30.03					153
Forfeited	(47)	36.91
Expired	(47)	55.07
Outstanding at December 31, 2022	907	$	45.47			5.6	$	3,868
Granted	3	41.84		$	22.12
Exercised	(189)	44.09					2,894
Forfeited	(21)	33.45
Expired	(11)	55.15
Outstanding at December 31, 2023	689	$	46.05			4.9	$	8,370
Exercisable at December 31, 2023	580	$	48.75			4.5	$	5,815

Restricted stock activity

A summary of RSA activity under the Plan during the years ended December 31, 2023, 2022, and 2021 is presented below:

(in thousands, except per share and remaining term data)	Shares	Weighted Average Grant Date Fair Value		Weighted Average Remaining Term (years)
Unvested at December 31, 2020	352	$	48.14	2.7
Granted	541	33.02
Vested	(125)	48.32
Forfeited	(61)	48.16
Unvested at December 31, 2021	707	$	36.52	2.8
Granted	748	32.76
Vested	(245)	36.99
Forfeited	(69)	38.08
Unvested at December 31, 2022	1,141	$	33.86	2.6
Granted	674	43.30
Vested	(383)	34.59
Forfeited	(81)	38.10
Unvested at December 31, 2023	1,351	$	38.11	2.4

Performance shares activity

A summary of PSU activity under the Plan during the years ended December 31, 2023 and 2022 is presented below:

(in thousands, except per share and remaining term data)	Shares	Weighted Average Grant Date Fair Value		Weighted Average Remaining Term (years)
Unvested at December 31, 2022	—	$	—	—
Granted	85	41.84
Vested	—	—
Forfeited	(1)	41.84
Unvested at December 31, 2023	84	$	41.84	2.0