Stockholders' Equity (Tables)

6 Months Ended

Jul. 31, 2014

Summary of Stock Option Activity

A summary of stock option activity for the six months ended July 31, 2014 is as follows:

						Weighted
				Weighted		average
				average		remaining		Aggregate
	Number			exercise		contractual		intrinsic
	of shares			price		term (in years)		value
Options outstanding at January 31, 2014		25,424,437		$	3.22		8.5	$	726,649,586
Options granted		425,000			28.55
Options exercised		(2,848,717	)		0.78			$	62,458,072
Options forfeited/cancelled		(873,310	)		4.18
Options outstanding at July 31, 2014		22,127,410		$	3.99		8.2	$	441,740,526
Options vested and exercisable at July 31, 2014		3,795,267		$	1.43		6.9	$	85,045,568
Options vested and exercisable at July 31, 2014 and expected      to vest thereafter		20,704,353		$	3.95		8.2	$	414,093,778

Summary of Restricted Stock Unit (RSU) Activity

A summary of restricted stock unit (RSU) activity for the six months ended July 31, 2014 is as follows:

				Weighted
	Unreleased			average
	Restricted			grant date
	Stock Units			fair value
Unreleased RSUs at January 31, 2014		156,050		$	36.52
RSUs granted		406,535			24.35
RSUs vested		(29,292	)		22.64
RSUs forfeited/cancelled		(23,039	)		36.83
Unreleased RSUs at July 31, 2014		510,254		$	27.61

Schedule of Weighted-Average Assumptions Used to Estimate Fair Value of Options Granted

The following table presents the weighted-average assumptions used to estimate the fair value of options granted during the periods presented:

	Three Months Ended July 31,				Six Months Ended July 31,
	2014		2013		2014	2013
Volatility		50%		50%	48% – 50%	42% – 50%
Expected life (in years)	6.28 – 6.32			6.32	6.27 – 6.32	6.32 – 8.23
Risk-free interest rate	1.93% – 1.94%		1.16% – 1.69%		1.85% – 1.94%	1.03% – 1.69%
Dividend yield	—%		—%		—%	—%

Schedule of Weighted-Average Assumptions Used to Calculate Out Stock-Based Compensation for Each Stock Purchase under ESPP

The following table presents the weighted-average assumptions used to calculate our stock-based compensation for the stock purchases under the ESPP:

	Six Months Ended
	July 31, 2014
Volatility		44	%
Expected life (in years)		0.58
Risk-free interest rate		0.10	%
Dividend yield	—		%