Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2020

Stock-Based Compensation Expense

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

	Three Months Ended March 31,
	2020		2019
	(Amounts in thousands)
Cost of product revenue	$	433	$	324
Research and development		372		321
Selling, general and administrative		3,360		2,606
Total stock-based compensation	$	4,165	$	3,251

Summary of Option Activity

Information regarding option activity for the three months ended March 31, 2020 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, 2019		957,559		$	30.81
Granted		25,836		$	86.10
Exercised		(67,877	)	$	23.56
Forfeited/expired/cancelled		—		$	—
Options outstanding at March 31, 2020		915,518		$	32.91		6.64	$	58,257
Options exercisable at March 31, 2020		555,159		$	26.77		5.65	$	38,734
Vested and expected to vest at March 31, 2020(1)		885,461					6.59	$	56,522

(1) Represents the number of vested options as of March 31, 2020 plus the number of unvested options expected to vest as of March 31, 2020 based on the unvested outstanding options at March 31, 2020 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 restricted stock units and performance stock units, for the three months ended March 31, 2020 under the Plans is summarized below:

	Shares			Weighted- Average Remaining Contractual Term (in Years)		Aggregate Intrinsic Value (in Thousands)
Unvested at December 31, 2019		734,984
Awarded		127,286
Vested		(132,053	)
Forfeited/expired/cancelled		(13,587	)
Unvested at March 31, 2020		716,630			3.69	$	69,183
Vested and expected to vest at March 31, 2020(1)		656,225			3.43	$	63,352

(1) Represents the number of vested stock units as of March 31, 2020 plus the number of unvested stock units expected to vest as of December 31, 2019 based on the unvested outstanding stock units at December 31, 2019 adjusted for estimated forfeiture rates of 8% for awards granted to non-executive level employees and 3% for awards granted to executive level employees.