Stockholders' Equity (Tables)

9 Months Ended

Sep. 30, 2021

Stock-Based Compensation Expense

The following table presents stock-based compensation expense in the Company’s consolidated statements of comprehensive income:

	Three Months Ended  September 30,				Nine Months Ended September 30,
	2021		2020		2021		2020
	(Amounts in thousands)
Cost of product revenue	$	489	$	563	$	1,444	$	1,421
Research and development		698		326		2,209		1,092
Selling, general and administrative		5,605		3,336		16,823		9,979
Total stock-based compensation	$	6,792	$	4,225	$	20,476	$	12,492

Summary of Option Activity

Information regarding option activity for the nine months ended September 30, 2021 under the Plans is summarized below:

	Shares			Weighted average exercise price		Weighted-Average Remaining Contractual Term (in Years)		Aggregate Intrinsic Value (in Thousands)
Options outstanding at December 31, 2020		696,711		$	43.88		6.90	$	102,958
Granted		38,824		$	202.88
Exercised		(70,935	)	$	28.00
Forfeited/expired/cancelled		(6,000	)	$	48.05
Options outstanding at September 30, 2021		658,600		$	54.93		6.55	$	154,152
Options exercisable at September 30, 2021		343,909		$	38.68		5.87	$	86,085
Vested and expected to vest at September 30, 2021(1)		637,504					6.53	$	149,348

(1)Represents the number of vested options as of September 30, 2021 plus the number of unvested options expected to vest as of September 30, 2021 based on the unvested outstanding options at September 30, 2021 adjusted for estimated forfeiture rates of 8% for awards granted to non-executive level employees and 3% for awards granted to executive level employees.

Summary of Restricted Stock Unit Activity

The fair value of stock units is calculated using the closing price of the Company’s common stock on the date of grant. Information regarding stock unit activity, which includes activity for RSUs and performance stock units, for the nine months ended September 30, 2021 under the Plans is summarized below:

	Shares			Weighted-Average Remaining Contractual Term (in Years)		Aggregate Intrinsic Value (in Thousands)
Unvested at December 31, 2020		665,540			3.32	$	127,904
Awarded		164,968
Vested		(185,922	)
Forfeited/expired/cancelled		(24,825	)
Unvested at September 31, 2021		619,761			2.94	$	179,105
Unvested and expected to vest at September 30, 2021(1)		623,642			2.61	$	180,226

(1)Represents the number of vested stock units as of September 30, 2021 plus the number of unvested stock units expected to vest as of September 30, 2021 based on the unvested outstanding stock units at September 30, 2021 adjusted for estimated forfeiture rates of 8% for awards granted to non-executive level employees and 3% for awards granted to executive level employees.