Stockholders' Equity (Tables)

3 Months Ended

Apr. 30, 2020

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

A summary of stock option activity for the three months ended April 30, 2020 is as follows:



	Number of shares		Weighted average exercise price		Weighted average remaining contractual term (in years)	Aggregate intrinsic value
Options outstanding at January 31, 2020	13,448,026		$	40.64	5.4	$	1,426,502,005
Options granted	1,264,192		172.55
Options exercised	(645,515	)	15.92
Options forfeited/cancelled	(44,252	)	84.44
Options outstanding at April 30, 2020	14,022,451		$	53.40	5.6	$	1,926,725,769
Options vested and exercisable at April 30, 2020	6,759,113		$	11.99	3.3	$	1,208,620,921
Options vested and exercisable at April 30, 2020 and expected to vest thereafter	14,022,451		$	53.40	5.6	$	1,926,725,769

Summary of Restricted Stock Unit (RSU) Activity

A summary of restricted stock unit (RSU) activity for the three months ended April 30, 2020 is as follows:



	Unreleased restricted stock units		Weighted average grant date fair value
Balance at January 31, 2020	1,818,622		$	95.23
RSUs granted	373,055		171.58
RSUs vested	(289,471	)	75.03
RSUs forfeited/cancelled	(29,608	)	74.92
Balance at April 30, 2020	1,872,598		$	113.90

Schedule of Weighted-Average Assumptions Used to Estimate Grant Date Fair Value of Options Granted

The following table presents the weighted-average assumptions used to estimate the grant date fair value of options granted during the periods presented:



	Three months ended April 30,
	2020	2019
Volatility	39% - 41%	41%
Expected term (in years)	6.25 - 7.25	5.75 - 6.35
Risk-free interest rate	0.51% - 1.43%	2.36% - 2.52%
Dividend yield	—%	—%