Stock-based Compensation

3 Months Ended

Apr. 30, 2015

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

8. Stock-based Compensation

The following table presents the classification of stock-based compensation for the periods indicated:

	Three Months Ended April 30,
	2015		2014
	(in thousands)
Stock-based compensation:
Cost of revenue	$	124	$	59
Research and development		3,094		1,590
Selling, general and administrative		2,264		1,225
Total stock-based compensation	$	5,482	$	2,874

As of April 30, 2015, total unrecognized compensation cost related to unvested stock options and unvested restricted stock units was $11.3 million and $46.1 million, respectively, and is expected to be recognized over a weighted-average period of 2.49 years and 2.72 years, respectively.

The following table sets forth the weighted-average assumptions used to estimate the fair value of stock options and employee stock purchase plan awards for the periods indicated:

	Three Months Ended April 30,
	2015			2014
Stock Options:
Volatility		60	%		65	%
Risk-free interest rate		1.74	%		1.95	%
Expected term (years)	6.08				6.05
Dividend yield		0	%		0	%
Employee stock purchase plan awards:
Volatility		63	%		57	%
Risk-free interest rate		0.15	%		0.08	%
Expected term (years)		0.5			0.5
Dividend yield		0	%		0	%

The following table summarizes stock option activities for the three months ended April 30, 2015:

	Option Outstanding
										Weighted-
								Total Intrinsic		Average
						Weighted-		Value of		Remaining		Aggregate
				Weighted-		Average		options		Contactual		Intrinsic
				Average		Grant-date		Exercised		Term		Value
	Shares			Exercise Price		Fair Value		(in thousands)		(in years)		(in thousands)
Outstanding at January 31, 2015		2,281,909		$	13.00
Granted		66,100			64.39	$	36.30
Exercised		(272,334	)		7.88			$	16,431
Forfeited		(5,580	)		24.62
Outstanding at April 30, 2015		2,070,095			15.28					6.36		$	119,790
Exercisable at April 30, 2015		1,399,112		$	7.99						5.32	$	91,169
Vested and expected to vest at April 30, 2015		2,027,575		$	14.84						6.31	$	118,221

Exercisable shares include options with early exercise rights. The vested and expected-to-vest options are calculated based on vesting schedule of each grant as of the reporting date.

The intrinsic value of options outstanding, exercisable and expected-to-vest options are calculated based on the difference between the fair market value of the Company’s ordinary shares on the reporting date and the exercise price. The closing price of the Company’s ordinary shares was $73.15 on April 30, 2015, as reported by The NASDAQ Global Market. The intrinsic value of exercised options is calculated based on the difference between the fair market value of the Company’s ordinary shares on the exercise date and the exercise price.

The following table summarizes restricted stock units activities for the periods indicated:

				Weighted-
				Average
				Grant-Date
	Shares			Fair Value
Unvested at January 31, 2015		1,980,448		$	26.82
Granted		22,000			64.39
Vested		(178,534	)		23.87
Forfeited		(2,459	)		35.97
Unvested at April 30, 2015		1,821,455		$	27.55

As of April 30, 2015, the aggregate intrinsic value of unvested restricted stock units was $133.2 million.

Non-employee Stock-based Compensation

The fair value of awards granted to non-employees is determined on the date of grant and remeasured at the end of each reporting period until such awards vest. The non-employee stock-based compensation was not material for the three months ended April 30, 2015 and 2014, respectively.

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

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