Stock-Based Compensation (Tables)

9 Months Ended

Oct. 31, 2015

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:

	Shares Subject to Options Outstanding					Weighted-Average
	Shares Subject to			Weighted-		Remaining
	Outstanding			Average Exercise		Contractual Life		Aggregate
	Options			Price		(Years)		Intrinsic Value
								(in thousands)
Balance as of January 31, 2015		17,465,571		$	5.67		7.80	$	229,713
Options granted		1,898,700			15.62
Option exercised		(1,734,155	)		3.05
Options forfeited/cancelled		(1,289,083	)		8.14
Balance as of October 31, 2015		16,341,033		$	6.90		7.37	$	106,264
Vested and expected to vest as of October 31, 2015		16,081,099		$	6.83		7.35	$	105,566
Exercisable as of October 31, 2015		9,321,360		$	4.02		6.64	$	82,215

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, 2015		4,939,709		$	15.66
Granted		5,652,733			15.83
Vested, net of shares withheld for employee payroll taxes		(728,806	)		16.48
Forfeited/cancelled, including shares withheld for    employee payroll taxes		(1,300,475	)		16.21
Unvested balance - October 31, 2015		8,563,161		$	15.62

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				Nine Months Ended
	October 31,				October 31,
	2015		2014		2015		2014
Cost of revenue	$	1,272	$	472	$	3,164	$	1,102
Research and development		6,455		3,207		18,021		8,220
Sales and marketing		5,005		3,122		14,030		8,306
General and administrative		2,672		1,712		7,632		4,716
Total stock-based compensation	$	15,404	$	8,513	$	42,847	$	22,344

Summary of Estimated Fair Value of Employee Stock Options

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

	Three Months Ended											Nine Months Ended
	October 31,											October 31,
	2015					2014						2015						2014
Employee Stock Options
Expected term (in years)		5.9		-	6.0						6.0		5.5		-		6.1		5.7		-		6.1
Risk-free interest rate		1.5	%	-	1.6%						1.8%		1.5	%	-		1.9%		1.8	%	-		2.1%
Volatility					42%		46	%	-		47%		42	%	-		44%		46	%	-		49%
Dividend yield					0%					0%						0%						0%
Employee Stock Purchase Plan
Expected term (in years)	0.5			-	2.0						—	0.5			-		2.0						—
Risk-free interest rate		0.2	%	-	0.8%						—		0.2	%	-		0.8%						—
Volatility		33	%	-	39%						—		33	%	-		41%						—
Dividend yield					0%						—						0%						—

Restricted Stock

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, 2015		172,661		$	9.60
Granted		28,864			17.54
Vested		(75,874	)		12.68
Forfeited/cancelled, including shares withheld for    employee payroll taxes		(47,775	)		9.94
Unvested balance - October 31, 2015		77,876		$	9.33