We have three equity incentive plans, the 2010 Stock Plan ("2010 Plan"), 2011 Stock Plan ("2011 Plan") and 2016 Equity Incentive Plan ("2016 Plan"). Our stockholders approved the 2016 Plan in March 2016 and it became effective in connection with our initial public offering ("IPO"). As a result, at the time of the IPO, we ceased granting additional stock awards under the 2010 Plan and 2011 Plan and both plans were terminated. Any outstanding stock awards under the 2010 Plan and 2011 Plan remain outstanding, subject to the terms of the applicable plan and award agreements, until such shares are issued under those stock awards, by exercise of stock options or settlement of restricted stock units ("RSUs"), or until those stock awards become vested or expired by their terms.

Under the 2016 Plan, we may grant incentive stock options, non-statutory stock options, restricted stock, RSUs and stock appreciation rights to employees, directors and consultants. We initially reserved 22.4 million shares of our Class A common stock for issuance under the 2016 Plan. The number of shares of Class A common stock available for issuance under the 2016 Plan will also include an annual increase on the first day of each fiscal year, beginning in fiscal 2018, equal to the lesser of: 18.0 million shares, 5% of the outstanding shares of all classes of common stock as of the last day of our immediately preceding fiscal year, or such other amount as may be determined by the Board. Accordingly, on August 1, 2020 and 2021, the number of shares of Class A common stock available for issuance under the 2016 Plan increased by 10.1 million and 10.7 million shares, respectively, pursuant to these provisions. As of April 30, 2022, we had reserved a total of 41.6 million shares for the issuance of equity awards under the Stock Plans, of which 16.4 million shares were still available for grant.

Performance RSUs — We have granted RSUs that have both service and performance conditions to our executives and employees ("Performance RSUs"). Vesting of Performance RSUs is subject to continuous service and the satisfaction of certain performance targets. While we recognize cumulative stock-based compensation expense for the portion of the awards for which both the service condition has been satisfied and it is probable that the performance conditions will be met, the actual vesting and settlement of Performance RSUs are subject to the performance conditions actually being met.

In connection with his hiring, in December 2020, the Compensation Committee of our Board of Directors approved the grant of 703,117 RSUs subject to certain market conditions ("MSUs") to our CEO. These MSUs have a weighted average grant date fair value per unit of $35.69 and will vest up to 133% based upon the achievement of certain stock price targets over a performance period of approximately 4.0 years, subject to his continuous service on each vesting date.

In order to align with the MSUs granted to our CEO, in December 2020, the Compensation Committee of our Board of Directors modified the vesting conditions for the 75,000 MSUs previously granted to another individual who was then serving as one of our executives. These modified MSUs had a weighted average grant date fair value per unit of $27.54 and vested based upon the achievement of a modified stock price target over the original performance period of approximately 3.9 years, subject to continuous service on each vesting date. The incremental compensation cost resulting from this modification was not material. Following the individual's resignation during the second quarter of fiscal 2022, his remaining unvested MSUs were cancelled.

In October 2021, the Compensation Committee of our Board of Directors approved the grant of approximately 0.4 million MSUs to certain of our executives. These MSUs have a weighted average grant date fair value per unit of $46.20 and will vest up to 200% based upon our total shareholder return over a performance period of approximately 2.8 years, subject to continuous service on each vesting date. Additional MSUs have since been granted with similar terms, but were not material.

We used Monte Carlo simulations to calculate the fair value of these awards on the grant date, or modification date, as applicable. A Monte Carlo simulation requires the use of various assumptions, including the stock price volatility and risk-free interest rate as of the valuation date corresponding to the length of time remaining in the performance period and expected dividend yield. We recognize stock-based compensation expense related to these MSUs using the graded vesting attribution method over the respective performance periods. As of April 30, 2022, approximately 1.2 million MSUs remained outstanding.

Below is a summary of RSU activity, including MSUs, under the Stock Plans:


	Number of Shares			Weighted Average Grant Date Fair Value per Share
	(in thousands)
Outstanding at July 31, 2021		21,708		$	30.98
Granted		13,059		$	33.90
Released		(7,722	)	$	32.42
Forfeited		(4,279	)	$	32.74
Outstanding at April 30, 2022		22,766		$	31.83

We did not grant any stock options during the nine months ended April 30, 2022. A total of 0.9 million stock options were exercised during the nine months ended April 30, 2022, with a weighted average exercise price per share of $4.48.

As of April 30, 2022, 2.4 million stock options, with a weighted average exercise price of $5.47 per share, a weighted average remaining contractual life of 1.7 years and an aggregate intrinsic value of $47.7 million, remained outstanding.

In December 2015, the Board adopted the 2016 Employee Stock Purchase Plan, which was subsequently amended in January 2016 and September 2016 and approved by our stockholders in March 2016 (the "Original 2016 ESPP"). The Original 2016 ESPP became effective in connection with our IPO. On December 13, 2019, during our 2019 Annual Meeting of Stockholders, our stockholders approved certain amendments to the Original 2016 ESPP. Under the amended and restated Original 2016 ESPP (the "2016 ESPP"), the maximum number of shares of Class A common stock available for sale is 11.5 million shares, representing an increase of 9.2 million shares.

The 2016 ESPP allows eligible employees to purchase shares of our Class A common stock at a discount through payroll deductions of up to 15% of eligible compensation, subject to caps of $25,000 in any calendar year and 1,000 shares on any purchase date. The 2016 ESPP provides for 12-month offering periods, generally beginning in March and September of each year, and each offering period consists of two six-month purchase periods.

On each purchase date, participating employees will purchase Class A common stock at a price per share equal to 85% of the lesser of the fair market value of our Class A common stock on (i) the first trading day of the applicable offering period or (ii) the last trading day of each purchase period in the applicable offering period. If the stock price of our Class A common stock on any purchase date in an offering period is lower than the stock price on the enrollment date of that offering period, the offering period will immediately reset after the purchase of shares on such purchase date and automatically roll into a new offering period.

During the nine months ended April 30, 2022, 2.8 million shares of common stock were purchased under the 2016 ESPP for an aggregate amount of $62.6 million. As of April 30, 2022, 2.4 million shares were available for future issuance under the 2016 ESPP.

We use the Black-Scholes option pricing model to determine the fair value of shares purchased under the 2016 ESPP with the following weighted average assumptions on the date of grant:


	Nine Months Ended April 30,
	2021			2022
Expected term (in years)		0.78			0.81
Risk-free interest rate		0.1	%		1.0	%
Volatility		56.9	%		43.4	%
Dividend yield		—	%		—	%

Total stock-based compensation expense recognized in the condensed consolidated statements of operations is as follows:


	Three Months Ended April 30,				Nine Months Ended April 30,
	2021		2022		2021		2022
	(in thousands)
Cost of revenue:
Product	$	1,291	$	1,830	$	4,454	$	5,529
Support, entitlements and other services		6,337		7,307		17,862		23,564
Sales and marketing		30,743		25,463		93,001		80,975
Research and development		40,802		35,467		114,747		109,709
General and administrative		16,113		14,439		38,874		43,321
Total stock-based compensation expense	$	95,286	$	84,506	$	268,938	$	263,098

As of April 30, 2022, unrecognized stock-based compensation expense related to outstanding stock awards was approximately $668.3 million and is expected to be recognized over a weighted average period of approximately 2.5 years.