Stock-based Compensation

9 Months Ended

Oct. 31, 2016

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

10. Stock-based Compensation

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

	Three Months Ended October 31,				Nine Months Ended October 31,
	2016		2015		2016		2015
	(in thousands)
Stock-based compensation:
Cost of revenue	$	282	$	157	$	773	$	408
Research and development		7,804		5,201		21,396		11,966
Selling, general and administrative		4,621		2,587		13,305		7,174
Total stock-based compensation	$	12,707	$	7,945	$	35,474	$	19,548

As of October 31, 2016, total unrecognized compensation cost related to unvested stock options was $9.1 million and is expected to be recognized over a weighted-average period of 2.05 years. Total unrecognized compensation cost related to unvested restricted stock units was $115.0 million and is expected to be recognized over a weighted-average period of 2.98 years. Total unrecognized compensation cost related to unvested restricted stock awards was $8.1 million and is expected to be recognized over a weighted-average period of 1.89 years.

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 October 31,						Nine Months Ended October 31,
	2016			2015			2016			2015
Stock Options:
Volatility		39	%		55	%		38	%		57	%
Risk-free interest rate		1.27	%		1.70	%		1.51	%		1.73	%
Expected term (years)	6.08				6.08		5.98				6.08
Dividend yield		0	%		0	%		0	%		0	%
Employee stock purchase plan awards:
Volatility		41	%		63	%		54	%		63	%
Risk-free interest rate		0.49	%		0.27	%		0.51	%		0.21	%
Expected term (years)		0.5			0.5			0.5			0.5
Dividend yield		0	%		0	%		0	%		0	%

The following table summarizes stock option activities for the nine months ended October 31, 2016:

	Option Outstanding
										Weighted-
								Total Intrinsic		Average
						Weighted-		Value of		Remaining		Aggregate
				Weighted-		Average		options		Contractual		Intrinsic
				Average		Grant-date		Exercised		Term		Value
	Shares			Exercise Price		Fair Value		(in thousands)		(in years)		(in thousands)
Outstanding at January 31, 2016		1,853,390		$	19.36
Granted		93,100			46.10	$	17.99
Exercised		(205,018	)		13.98			$	9,469
Forfeited		(10,753	)		50.76
Expired		(7,721	)		14.12
Outstanding at October 31, 2016		1,722,998			21.27					5.39		$	71,043
Exercisable at October 31, 2016		1,345,458		$	13.81						4.57	$	64,650

The intrinsic value of options outstanding and exercisable 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 on October 31, 2016 was $61.37, 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 activities for the periods indicated:

				Weighted-
				Average
				Grant-Date
	Shares			Fair Value
Unvested at January 31, 2016		2,495,488		$	47.04
Granted		662,573			67.91
Vested		(704,225	)		36.48
Forfeited		(22,030	)		45.94
Unvested at October 31, 2016		2,431,806		$	55.60

As of October 31, 2016, the aggregate intrinsic value of unvested restricted stock was $149.2 million.

- 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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