Equity Plans and Stock-based Compensation (Tables)

3 Months Ended

Mar. 31, 2022

Share-based Payment Arrangement [Abstract]

Stock Option Activity

A summary of the Company’s stock option activity and related information was as follows:

	Options Outstanding
	Number of Stock Options Outstanding	Weighted- Average Exercise Price	Weighted-Average Remaining Contractual Life (Years)	Aggregate Intrinsic Value (in thousands)
Balance as of December 31, 2021 (1)	18,101,584	4.08	5.5	$	87,425
Granted	705,512	7.84
Exercised	(667,724)	2.74
Cancelled/forfeited/expired	(645,344)	6.36
Balance as of March 31, 2022 (1)	17,494,028	4.20	5.1	$	60,108
Exercisable as of March 31, 2022 (2)	13,147,613	3.56	4.0	$	52,123

__________________

(1)Excluding Equity Awards of 2,677,500 shares and Milestone Options of 669,375 shares. See below for further details.

(2)Excluding 1,004,064 shares exercisable under the Equity Awards with weighted average exercise price of $19.61 per share as of March 31, 2022.

Assumptions for Fair Value of Stock Options

The fair value of stock options granted is estimated on the date of grant using the following assumptions:

	Three Months Ended March 31,
	2022		2021
Expected term (in years)	6.3		6.1
Risk-free interest rate	1.9	%	1.1	%
Expected volatility	55.0	%	56.0	%
Expected dividend rate	—		—

RSU Activity

A summary of the Company's RSU activity and related information is as follows:

	Number of RSUs	Weighted Average Grant Date Fair Value		Aggregate Intrinsic Value (in thousands)
Balance as of December 31, 2021	1,324,960	$	10.67	$	11,699
Granted	2,892,464	7.63
Released	(75,883)	10.55
Forfeited	(59,051)	10.95
Balance as of March 31, 2022	4,082,490	$	8.51	$	30,700

Stock-Based Compensation Expense

Stock-based compensation expense included in operating results was as follows (in thousands):

	Three Months Ended March 31,
	2022		2021
Cost of goods sold	$	516	$	276
Research and development	993		513
Selling, general and administrative	3,133		2,208
Total stock-based compensation expense	$	4,642	$	2,997