Stock-Based Compensation (Tables)

6 Months Ended

Jul. 31, 2016

Summary of Stock Option Activity Under Equity Incentive Plans and Related Information

The following table summarizes the stock option activity under the equity incentive plans and related information:

	SharesSubject to Options Outstanding					Weighted-Average
				Weighted-		Remaining
				Average Exercise		Contractual Life		Aggregate
	Shares			Price		(Years)		Intrinsic Value
								(in thousands)
Balance as of January 31, 2016		15,634,518		$	6.92		7.12	$	82,541
Options granted		468,136			11.99
Option exercised		(1,676,632	)		2.51
Options forfeited/cancelled		(1,162,383	)		13.05
Balance as of July 31, 2016		13,263,639		$	7.12		6.76	$	75,120
Vested and expected to vest as of July 31, 2016		13,096,353		$	7.06		6.74	$	74,772
Exercisable as of July 31, 2016		9,529,567		$	5.40		6.25	$	67,350

Summary of Restricted Stock Unit Activity Under Equity Incentive Plans and Related Information

The following table summarizes the restricted stock unit activity under the equity incentive plans and related information:

	Number of			Weighted-
	Restricted			Average
	Stock Units			Grant Date
	Outstanding			Fair Value
Unvested balance - January 31, 2016		8,204,968		$	15.54
Granted		4,644,607			12.19
Vested, net of shares withheld for employee    payroll taxes		(1,012,038	)		16.37
Forfeited/cancelled, including shares withheld for    employee payroll taxes		(2,166,582	)		15.38
Unvested balance - July 31, 2016		9,670,955		$	13.88

Summary of Components of Stock-Based Compensation Expense

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

	Three Months Ended				Six Months Ended
	July 31,				July 31,
	2016		2015		2016		2015
Cost of revenue	$	1,830	$	1,041	$	3,342	$	1,892
Research and development		7,348		6,303		13,872		11,566
Sales and marketing		6,416		4,742		11,646		9,025
General and administrative		3,470		2,642		6,293		4,960
Total stock-based compensation	$	19,064	$	14,728	$	35,153	$	27,443

Summary of Estimated Fair Value of Employee Stock Options

We estimated the fair value of employee stock options and 2015 ESPP purchase rights using a Black-Scholes option pricing model with the following assumptions:

	Three Months Ended										Six Months Ended
	July 31,										July 31,
	2016					2015					2016					2015
Employee Stock Options
Expected term (in years)		5.5		-	6.0		5.5		-	6.1		5.5		-	6.0		5.5		-	6.1
Risk-free interest rate		1.3	%	-	1.5%		1.8	%	-	1.9%		1.3	%	-	1.5%		1.6	%	-	1.9%
Volatility					43%		42	%	-	43%					43%		42	%	-	44%
Dividend yield					0%					0%					0%					0%
Employee Stock Purchase Plan
Expected term (in years)		0.5		-	2.0	0.5			-	2.0		0.5		-	2.0	0.5			-	2.0
Risk-free interest rate		0.5	%	-	0.9%		0.2	%	-	0.7%		0.5	%	-	0.9%		0.2	%	-	0.7%
Volatility		46	%	-	60%		39	%	-	41%		46	%	-	60%		39	%	-	41%
Dividend yield					0%					0%					0%					0%

Restricted Stock Awards

Summary of Restricted Stock Award Activity Under Equity Incentive Plans and Related Information

The following table summarizes the restricted stock activity under the equity incentive plans and related information:

	Number of			Weighted-
	Restricted			Average
	Stock			Grant Date
	Outstanding			Fair Value
Unvested balance - January 31, 2016		30,607		$	11.38
Vested, net of shares withheld for employee    payroll taxes		(15,920	)		11.21
Forfeited/cancelled, including shares withheld for    employee payroll taxes		(2,783	)		9.77
Unvested balance - July 31, 2016		11,904		$	11.99