Stock-based Compensation

9 Months Ended

Oct. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-based Compensation

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,
	2020		2019		2020		2019
	(in thousands)
Stock-based compensation:
Cost of revenue	$	368	$	335	$	981	$	922
Research and development		11,496		10,601		31,402		31,306
Selling, general and administrative		7,113		6,372		19,024		17,740
Total stock-based compensation	$	18,977	$	17,308	$	51,407	$	49,968

During the three and nine months ended October 31, 2020, approximately $1.9 million and $2.8 million of stock-based compensation expense was accrued in the accrued and other current liabilities in the condensed consolidated balance sheets, respectively. As of October 31, 2020, total unrecognized compensation cost related to unvested stock options was $3.1 million and is expected to be recognized over a weighted-average period of 2.37 years. Total unrecognized compensation cost related to unvested restricted stock units was $137.3 million and is expected to be recognized over a weighted-average period of 2.54 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,
	2020			2019			2020			2019
Stock Options:
Volatility		52	%		52	%		52	%		52	%
Risk-free interest rate		0.40	%		1.39	%		0.52	%		1.84	%
Expected term (years)	5.81			6.09			5.84			6.02
Dividend yield		0	%		0	%		0	%		0	%
Employee stock purchase plan awards:
Volatility		58	%		46	%		59	%		47	%
Risk-free interest rate		0.12	%		1.93	%		0.21	%		2.23	%
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 period indicated:

	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, 2020		1,124,646		$	32.93
Granted		36,700			53.05	$	25.45
Exercised		(207,876	)		12.31			$	9,224
Forfeited		(11,301	)		46.74
Expired		(21,422	)		75.47
Outstanding at October 31, 2020		920,747			37.23					4.42		$	18,266
Exercisable at October 31, 2020		790,911		$	35.19						3.75	$	17,504

The intrinsic value of options outstanding and exercisable is 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, 2020 was $54.67, 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 the restricted stock units activities for the period indicated:

				Weighted-
				Average
				Grant-Date
	Shares			Fair Value
Unvested at January 31, 2020		2,617,266		$	50.30
Granted		1,445,544			52.61
Vested		(901,392	)		51.17
Forfeited		(74,109	)		54.87
Unvested at October 31, 2020		3,087,309		$	51.02

As of October 31, 2020, the aggregate intrinsic value of unvested restricted stock units was $168.8 million.