Stock-based Compensation

6 Months Ended

Jul. 31, 2023

Share-Based Payment Arrangement [Abstract]

10. Stock-based Compensation

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


	Three Months Ended July 31,				Six Months Ended July 31,
	2023		2022		2023		2022
	(in thousands)
Stock-based compensation:
Cost of revenue	$	885	$	362	$	1,826	$	711
Research and development		18,550		17,883		36,911		35,034
Selling, general and administrative		8,687		8,664		16,650		18,205
Total stock-based compensation	$	28,122	$	26,909	$	55,387	$	53,950

As of July 31, 2023, approximately $1.8 million of stock-based compensation expense was accrued in accrued and other current liabilities in the condensed consolidated balance sheets. Total unrecognized compensation cost related to unvested stock options at July 31, 2023 was $10.8 million and is expected to be recognized over a weighted-average period of 1.55 years. Total unrecognized compensation cost related to unvested restricted stock units at July 31, 2023 was $176.0 million and is expected to be recognized over a weighted-average period of 2.29 years.

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


	Three Months Ended July 31,				Six Months Ended July 31,
	2023		2022		2023			2022
Employee stock purchase plan awards:
Volatility		—		—		59	%		89	%
Risk-free interest rate		—		—		4.73	%		0.86	%
Expected term (years)		—		—	0.5			0.5
Dividend yield		—		—		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, 2023		484,791		$	42.18
Exercised		(48,807	)		24.70		$	2,784
Forfeited		(707	)		42.63
Expired		(394	)		103.70
Outstanding at July 31, 2023		434,883			44.09					3.96	$	17,424
Exercisable at July 31, 2023		358,508		$	45.87					3.35	$	13,670

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 July 31, 2023 was $83.42, 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 unit activities for the period indicated:


				Weighted-
				Average
				Grant-Date
	Shares			Fair Value
Unvested at January 31, 2023		2,573,359		$	86.81
Granted		436,857			88.36
Vested		(698,757	)		77.60
Forfeited		(80,406	)		71.15
Unvested at July 31, 2023		2,231,053		$	90.57

As of July 31, 2023, the aggregate intrinsic value of unvested restricted stock units was $186.1 million.