The Company's 2008 Equity Incentive Plan (the "2008 Plan"), as amended on March 10, 2016, allowed for the issuance of up to 25,912,531 shares of common stock. Awards granted under the 2008 Plan may be incentive stock options ("ISOs"), nonqualified stock options ("NQSOs"), restricted stock and restricted stock units. The 2008 Plan is administered by the Company's Board of Directors, which determines the terms of the options granted, the exercise price, the number of shares subject to option and the option vesting period. No ISO or NQSO is exercisable after 10 years from the date of grant, and option awards will typically vest over a four-year period.

The 2008 Plan was terminated in connection with the adoption of the Company's 2016 Equity Incentive Plan (the "2016 Plan") in December 2016, and since the 2008 Plan termination the Company has not granted and will not grant any additional awards under the 2008 Plan. However, the 2008 Plan will continue to govern the terms and conditions of the outstanding awards previously granted thereunder.

In December 2016, the Company's Board of Directors adopted, and its stockholders approved, the 2016 Plan. The number of shares reserved for issuance under the 2016 Plan will increase on the first day of each fiscal year during the term of the 2016 Plan by the lesser of: (i) 10,000,000 shares, (ii) 4% of the outstanding shares of common stock as of the last day of the immediately preceding fiscal year; or (iii) such other amount as the Company's Board of Directors may determine. On February 1, 2021, the number of shares of common stock available for issuance under the 2016 Plan was automatically increased according to its terms by 4,959,567 shares. In addition, the shares reserved for issuance under the 2016 Plan also include shares returned to the 2008 Plan as the result of expiration or termination of options or other awards. As of January 31, 2022, the number of shares available for future award under the 2016 Plan is 1,425,786.

The following table summarizes the activity related to the Company's stock options:


	Options Outstanding
	Outstanding Stock Options	Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Life (in years)	Aggregate Intrinsic Value (in thousands)
Balance, January 31, 2021	8,871,890	$	7.64	4.94	$	81,906
Granted	—	$	—
Exercised	(2,220,276)	$	8.65
Forfeited or canceled	(30,913)	$	11.33
Balance, January 31, 2022	6,620,701	$	7.28	4.32	$	11,723
Vested and expected to vest	6,578,465	$	7.25	4.31	$	11,723
Exercisable at January 31, 2022	6,420,701	$	7.12	4.28	$	11,723


	Options	Weighted-Average Grant Date Fair Value
Nonvested as of January 31, 2021	544,911	$	5.55
Granted	—	$	—
Vested	(344,515)	$	5.25
Forfeited	(396)	$	5.95
Balance as of January 31, 2022	200,000	$	6.06

The aggregate intrinsic value of options vested and expected to vest and exercisable is calculated based on the difference between the exercise price and the fair value of the Company’s common stock as of January 31, 2022. The fair value of the common stock is the Company’s closing stock price as reported on the New York Stock Exchange.

The aggregate intrinsic value of exercised options was $13.5 million, $31.8 million and $48.0 million for the fiscal years ended January 31, 2022, 2021 and 2020, respectively, and is calculated based on the difference between the exercise price and the fair value of the Company’s common stock as of the exercise date.

The following table summarizes the activity related to the Company's restricted stock and restricted stock units:


	Outstanding	Weighted-Average Grant Date Fair Value
Balance as of January 31, 2021	9,545,352	$	16.71
Granted	7,831,853	$	12.94
Vested and converted to shares	(4,426,715)	$	15.76
Forfeited or canceled	(2,766,276)	$	16.09
Balance as of January 31, 2022	10,184,214	$	14.38

The estimated weighted-average grant date fair value of restricted stock and restricted stock units granted was $12.94, $15.52, and $18.71 per share for the fiscal years ended January 31, 2022, 2021, and 2020, respectively. The fair value of the common stock is the Company’s closing stock price as reported on the New York Stock Exchange.

The total fair value of restricted stock and restricted stock units vested was $69.8 million, $72.4 million, and $54.7 million for the fiscal years ended January 31, 2022, 2021, and 2020, respectively.

In March 2017, the Company's Board of Directors adopted, and its stockholders approved, the 2017 Employee Stock Purchase Plan ("ESPP"), which became effective on the date it was adopted. The number of shares of the Company's common stock that will be available for sale to employees under the ESPP increases annually on the first day of each fiscal year, in an amount equal to the lesser of: (i) 2,500,000 shares; (ii) 1% of the outstanding shares of the Company's common stock as of the last day of the immediately preceding fiscal year; or (iii) such other amount as the administrator may determine. On February 1, 2021, the number of shares of common stock available for issuance under the ESPP was automatically increased according to its terms by 1,239,891 shares. As of January 31, 2022, a total of 3,543,696 shares of the Company's common stock are available for sale to employees under the ESPP.

In connection with the offering period which ended on March 15, 2021, 282,119 shares of common stock were purchased under the ESPP at a purchase price of $13.53 per share for total proceeds of $3.8 million. In connection with the offering period which ended on September 15, 2021, 248,633 shares of common stock were purchased under the ESPP at a purchase price of $10.73 per share for total proceeds of $2.7 million.

A new offering period began on September 15, 2021 and will end on March 15, 2022. As of January 31, 2022, 291,079 shares are estimated to be purchased at the end of the offering period and $2.4 million has been withheld on behalf of employees for these future purchases under the ESPP and is included in accounts payable, accrued expenses and other current liabilities.


	Fiscal year ended January 31,
	2022	2021	2020










Expected life (years)	0.50	0.50	0.50
Expected volatility	45.54% - 59.24%	51.44% - 65.48%	42.41% - 60.86%
Dividend yield	0.00%	0.00%	0.00%
Risk-free rate	0.05% - 0.06%	0.12% - 0.29%	1.93% - 2.52%

The expected life assumptions were based on each offering period's respective purchase date. The Company estimated the expected volatility assumption based on the historical volatility of its stock price. The risk-free rate assumptions were based on the U.S. treasury yield curve in effect at commencement of the offering period. The dividend yield assumption was zero as the Company has not historically paid any dividends and does not expect to declare or pay any dividends in the foreseeable future.

During the fiscal years ended January 31, 2022, 2021 and 2020, the Company recorded stock-based compensation expense associated with the ESPP of $2.2 million, $2.8 million and $2.7 million, respectively. As of January 31, 2022, total unrecognized compensation cost related to ESPP was $0.3 million, net of estimated forfeitures, which will be amortized over a weighted-average remaining period of 0.12 years.

A new offering period commences on the first trading day on or after March 15th and September 15th each year, or on such other date as the administrator will determine and will end on the first trading day, approximately six months later, on or after September 15th and March 15th, respectively. Participants may purchase the Company’s common stock through payroll deductions, up to a maximum of 15% of their eligible compensation. Unless changed by the administrator, the purchase price for each share of

common stock purchased under the ESPP will be 85% of the lower of the fair market value per share on the first trading day of the applicable offering period or the fair market value per share on the last trading day of the applicable offering period.

Stock-based compensation represents the cost related to stock-based awards granted in lieu of monetary payment. The Company measures stock-based compensation associated with stock-based awards issued to employees at the grant date, based on the estimated fair value of the award, and recognizes expense net of estimated forfeitures over the vesting period of the applicable award using the straight-line method.

The Company's stock-based compensation expense for the periods presented was as follows:


	Fiscal year ended January 31,
(in thousands)	2022		2021		2020
Cost of revenue	$	7,099	$	5,724	$	4,115
Sales and marketing	26,496		32,581		31,421
Research and development	20,654		17,071		13,212
General and administrative	19,231		16,918		19,022
Total stock-based compensation expense	$	73,480	$	72,294	$	67,770