Stock-Based Compensation Expense and Employee Benefit Plans (Tables)

9 Months Ended

Sep. 30, 2021

Schedule of Employee and Non-Employee Stock-Based Compensation Expense

The following table summarizes the components of stock-based compensation expense in the condensed consolidated statements of operations (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2021		2020		2021		2020

Cost of revenue	$	2,945	$	3,568	$	9,749	$	13,811
Research and development	5,678		4,103		15,876		14,913
Sales and marketing	4,391		2,234		12,486		8,358
General and administrative	7,952		5,830		19,198		20,303
	$	20,966	$	15,735	$	57,309	$	57,385

Schedule of Stock Option and RSU Activity

The following table summarizes the stock option activity under our stock plans during the reporting period:


	Outstanding Options
	Number of Shares	Weighted Average Exercise Price		Remaining Contractual Life (Years)	Aggregate Intrinsic Value

					(in thousands)








Balances at December 31, 2020	15,354,271	$	21.27	6.0	$	129,855

Exercised	(2,597,003)	23.90
Cancelled	(973,720)	14.94
Balances at September 30, 2021	11,783,548	21.22		5.4	50,366
Vested and expected to vest at September 30, 2021	11,619,420	21.38		5.4	48,719
Exercisable at September 30, 2021	9,328,149	24.26		4.9	25,881

The following table presents the stock activity and the total number of shares available for grant under our stock plans as of September 30, 2021:


						Plan Shares Available for Grant













Balances at December 31, 2020						20,233,754
Added to plan						7,969,144
Granted						(5,566,751)

Cancelled						2,157,942
Expired						(358,854)
Balances at September 30, 2021						24,435,235

Schedule of RSU Activity and Related Information

A summary of our stock awards activity and related information is as follows:


	Number of Awards Outstanding	Weighted Average Grant Date Fair Value









Unvested Balance at December 31, 2020	6,418,788	$	13.71
Granted	5,566,751	24.27
Vested	(2,533,027)	16.65
Forfeited	(1,184,222)	16.37
Unvested Balance at September 30, 2021	8,268,290	19.54