Stock-Based Awards (Tables)

9 Months Ended

Sep. 30, 2018

Assumptions used to determine fair value of stock options granted


	Nine Months Ended
	September 30,
	2018		2017
Risk-free interest rate	2.65	%	1.89	%
Expected term (in years)	6.3		6.2
Expected volatility	96.56	%	93.84	%
Expected dividend yield	0	%	0	%

Summary of stock option activity


					Weighted
			Weighted		Average
			Average		Remaining	Aggregate
	Number		Exercise		Contractual	Intrinsic
	of Shares		Price		Term	Value
					(in years)
Outstanding as of December 31, 2017	3,328,757		$	20.69	8.28	$	19,812
Granted	1,397,900			21.25
Exercised	(59,450)			9.70
Forfeited and cancelled	(343,854)			24.82
Outstanding as of September 30, 2018	4,323,353		$	20.69	8.10	$	7,634
Options vested and expected to vest as of September 30, 2018	4,323,353		$	20.69	8.10	$	7,634
Options exercisable as of September 30, 2018	1,543,159	(1)	$	15.70	7.00	$	6,785

(1)

All options granted under the 2012 Plan are exercisable immediately, subject to a repurchase right in the Company’s favor that lapses as the option vests. This amount reflects the number of shares under options that were vested, as opposed to exercisable, as of September 30, 2018.

Summary of restricted stock units activity


		Weighted
		Average
		Grant Date
	Number	Fair Value
	of Shares	Per Share
Outstanding as of December 31, 2017	283,553	$	27.02
Granted	419,160		21.12
Vested	(106,202)		26.89
Forfeited and cancelled	(54,883)		23.76
Outstanding as of September 30, 2018	541,628	$	22.81

Stock-based compensation expense


	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2018		2017		2018		2017
Cost of revenue	$	194	$	130	$	560	$	130
Research and development		1,433		1,332		4,916		3,853
Sales and marketing		760		480		2,687		1,260
General and administrative		2,320		1,731		6,936		4,887
Total stock-based compensation expense	$	4,707	$	3,673	$	15,099	$	10,130