The Company maintains a defined contribution 401(k) plan (the “401(k) Plan”) for all of its eligible U.S. employees. Under the 401(k) Plan, eligible employees may contribute up to the Internal Revenue Service annual contribution limitation. The Company is responsible for administrative costs of the Plan. The Company has not had any matching contributions to date.

2004 Stock Plan. The 2004 Stock Plan provides for the grant of incentive stock options (“ISOs”) within the meaning of Section 422 of the Internal Revenue Code of 1986, as amended (the “Code”), nonstatutory stock options (“NSOs”), stock purchase rights to acquire restricted stock and restricted stock units. Upon the completion of the IPO, no additional awards will be granted under the 2004 Plan and the 2004 Plan was terminated. However, all outstanding stock options and other awards previously granted under the 2004 Plan will remain subject to the terms of the 2004 Plan.

2012 Equity Incentive Plan. The 2012 Equity Incentive Plan, or EIP, permits the grant of ISOs, within the meaning of Section 422 of the Code, to employees of the Company and any of the Company’s subsidiary corporations, and the grant of NSOs, stock appreciation rights, restricted stock, restricted stock units, performance units, performance shares, deferred stock units and dividend equivalents to employees, directors and consultants of the Company and any of the Company’s subsidiary corporations’ employees and consultants.

The exercise price of ISOs granted to a holder of more than 10% of the voting power of all classes of the Company’s shares shall be no less than 110% of fair market value on the grant date. The exercise price of ISOs granted to other employees and NSOs shall be no less than 100% of fair market value on the grant date. Options granted under the Plan have a term of up to 10 years from grant date. Options granted to new employees generally vest 25% on the first anniversary service date of the grant and remainder vest ratably over the following 36 months.

Restricted stock and restricted stock units granted to new employees generally vest as to 1/4th of the shares on the first anniversary service date of the grant and 1/16th of the shares vest every 3 months thereafter, so as to be 100% vested on the fourth anniversary of the vesting commencement date.

Vesting schedules for other service condition, market condition or performance condition awards vary and are subject to approval by the board of directors; provided that the performance condition associated awards shall not vest at all until the performance conditions are achieved and are subject to the award’s holders continuing to provide services to the Company through such vesting dates. The performance condition awards are automatically forfeited in their entirety, without any cost to or action by the Company, if there has been no achievement of the performance. The holders of restricted stock have voting power and other rights with respect to such shares, provided, however, that such shares are held in escrow and subject to forfeiture until the shares vested.

In the first quarter of fiscal year 2021 and 2020, the Company added 1,521,252 and 1,453,659 ordinary shares, respectively, to the ordinary shares reserved for issuance, pursuant to an “evergreen” provision contained in the EIP. Pursuant to such provision, on February 1st of each fiscal year, the number of ordinary shares reserved for issuance under the EIP is automatically increased by a number equal to the lesser of (i) 3,500,000 ordinary shares, (ii) four and one half percent (4.5%) of the aggregate number of ordinary shares outstanding on January 31st of the preceding fiscal year, or (iii) a lesser number of shares that may be determined by the Company’s Board of Directors.

Amended and Restated 2012 Employee Stock Purchase Plan. The Amended and Restated 2012 Employee Stock Purchase Plan, or ESPP, permits eligible participants to purchase ordinary shares at a discount through contributions up to 15% of their eligible compensation, subject to any IRS limitations. The ESPP provides each offering and purchasing period of six months in duration. The purchase price is 85% of the lower of the closing price of the Company’s ordinary shares on the first trading day of each offering period or on the purchase date.

In the first quarter of fiscal year 2021 and 2020, the Company added 422,570 and 403,794 ordinary shares, respectively, to the ordinary shares reserved for issuance, pursuant to an “evergreen” provision contained in the ESPP. Pursuant to such provision, on February 1st of each fiscal year, the number of ordinary shares reserved for issuance under the ESPP is automatically increased by a number equal to the lesser of (i) 1,500,000 ordinary shares, (ii) one and one quarter percent (1.25%) of the aggregate number of ordinary shares outstanding on such date, or (iii) an amount determined by the Company’s Board of Directors or a duly authorized committee of the Board of Directors.

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

For the twelve months ended January 31, 2021, approximately $4.4 million of stock-based compensation expense was accrued in accrued and other current liabilities in the consolidated balance sheets. As of January 31, 2021, 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 2.40 years. Total unrecognized compensation cost related to unvested restricted stock units was $123.9 million and is expected to be recognized over a weighted-average period of 2.35 years. The restricted stock awards were fully vested as of January 31, 2021.

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

	Year Ended January 31,
	2021			2020			2019
Stock Options:
Volatility		52	%		52	%		54	%
Risk-free interest rate		0.52	%		1.82	%		2.77	%
Expected term (years)		5.78			6.01			5.41
Dividend yield		0	%		0	%		0	%
Employee stock purchase plan awards:
Volatility		59	%		47	%		45	%
Risk-free interest rate		0.21	%		2.23	%		2.15	%
Expected term (years)		0.5			0.5			0.5
Dividend yield		0	%		0	%		0	%

Starting from fiscal year 2019, the Company calculates expected volatility for stock options based on its own historical stock price for a period commensurate with the expected term. In the prior fiscal year, the Company calculated expected volatility for stock options based on the weighted average of historical volatilities of its own stock price and the stock prices of similar companies that are publicly available for a period commensurate with the expected term. The Company calculates expected volatility for ESPP based on its own historical stock price for a period commensurate with the offering period.

The following table summarizes stock option activities for the periods 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, 2018		1,611,344		$	24.56
Granted		116,600			42.73	$	21.75
Exercised		(232,205	)		5.54			$	8,867
Forfeited		(20,974	)		53.50
Expired		(15,701	)		54.35
Outstanding at January 31, 2019		1,459,064			28.31
Granted		66,850			50.56	$	25.35
Exercised		(366,886	)		15.52			$	13,263
Forfeited		(14,931	)		46.29
Expired		(19,451	)		64.53
Outstanding at January 31, 2020		1,124,646			32.93
Granted		51,200			59.54	$	28.37
Exercised		(421,736	)		24.52			$	19,401
Forfeited		(11,618	)		46.69
Expired		(23,349	)		70.11
Outstanding at January 31, 2021		719,143		$	38.33					4.42		$	40,358
Exercisable at January 31, 2021		592,729		$	35.27						3.56	$	35,092

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 stock was $94.36 on January 29, 2021, 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 stock on the exercise date and the exercise price.

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

				Weighted-
				Average
				Grant-Date
	Shares			Fair Value
Unvested at January 31, 2018		2,103,281		$	56.45
Granted		1,367,751			40.03
Vested		(994,500	)		53.27
Forfeited		(81,016	)		53.57
Unvested at January 31, 2019		2,395,516			48.49
Granted		1,329,288			54.54
Vested		(1,012,581	)		51.24
Forfeited		(94,957	)		54.26
Unvested at January 31, 2020		2,617,266			50.30
Granted		1,499,203			53.45
Vested		(1,162,883	)		50.53
Forfeited		(81,785	)		54.48
Unvested at January 31, 2021		2,871,801		$	51.73

Total fair value as of the respective vesting dates of restricted stock and restricted stock units vested for the fiscal years ended January 31, 2021, 2020 and 2019 was approximately $69.0 million, $52.1 million, and $42.9 million, respectively. As of January 31, 2021, the aggregate intrinsic value of unvested restricted stock units was $271.0 million.