In March 2018, our Board of Directors adopted and our stockholders approved the 2018 Equity Incentive Plan (2018 Plan). The 2018 Plan authorizes the award of stock options, restricted stock awards, stock appreciation rights, restricted stock units (RSUs), performance awards, and stock bonuses. As of October 31, 2022, approximately 26.7 million shares of Class A common stock were reserved and available for issuance under the 2018 Plan. In addition, as of October 31, 2022, 4.3 million stock options and RSUs exercisable or settleable for Class B common stock were outstanding in the aggregate under our 2006 Stock Plan (2006 Plan) and 2015 Equity Incentive Plan (2015 Plan), which plans were terminated in May 2015 and April 2018, respectively. The 2006 Plan and 2015 Plan continue to govern outstanding equity awards granted thereunder.

The following tables summarize stock option activity and related information (in thousands, except weighted-average exercise price, weighted-average grant date fair value and average remaining contractual term):


	Shares Subject To Outstanding Stock Options	Weighted-Average Exercise Price		Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value
Balance, January 31, 2022	8,560	$	9.22	5.9	$	67,259
Granted	20	12.52
Exercised	(398)	5.23
Forfeited	(307)	14.21
Balance, October 31, 2022	7,875	9.23		5.2	14,046
Exercisable as of October 31, 2022	3,274	3.40		2.7	14,046
Vested and expected to vest as of October 31, 2022	7,743	9.15		5.2	14,046


	Three Months Ended October 31,				Nine Months Ended October 31,
	20221		20211		2022		2021

Weighted-average grant date fair value per share of options granted during each respective period	—		—		$	5.54	$	6.54
Aggregate intrinsic value of options exercised during each respective period	$	356	$	12,868	$	2,386	$	27,606

We used the Black-Scholes option-pricing model to estimate the fair value of our stock options granted during each respective period using the following assumptions1:


	Nine Months Ended October 31,
		2022			2021
Fair value of common stock		$	12.52		$15.64 - $15.87
Expected volatility		42.6		%	42.3% - 42.7%
Expected term (years)		5.8			6.0 - 6.1
Risk-free interest rate		3.0		%	1.0%- 1.1%
Expected dividend yield		—		%	—	%

The following table summarizes RSU activity and related information (in thousands, except weighted-average grant date fair value):


	Number of RSUs Outstanding	Weighted-Average Grant Date Fair Value
Balance, January 31, 2022	12,171	$	15.46
Granted	8,566	11.93
Vested	(4,418)	15.14
Forfeited	(2,085)	14.24
Balance, October 31, 2022	14,234	13.62

In March 2022, we granted PSUs to certain executives under our 2018 Plan. Each grant is divided into three tranches, each tranche having pre-established performance targets that if met, as determined quarterly by our Compensation Committee, would result in the shares attributable to such tranche being earned, subject to a service-based vesting condition. The shares attributable to unearned tranches will be forfeited on January 31, 2025, if the applicable performance criteria for such tranches are not met. Stock-based compensation expense is recognized if it is probable the performance targets (for each respective tranche) will be met during the performance period.

The following table summarizes PSU activity and related information (in thousands, except weighted-average grant date fair value):


	Number of PSUs Outstanding	Weighted-Average Grant Date Fair Value
Balance, January 31, 2022	—	$	—
Granted	2,905	15.21
Vested	—	—
Forfeited	—	—
Balance, October 31, 2022	2,905	$	15.21

In March 2018, our Board of Directors adopted and our stockholders approved the 2018 Employee Stock Purchase Plan (ESPP). This plan is broadly available to our employees in the United States and certain other countries in which we operate. A total of 4.6 million shares of Class A common stock were reserved and available for issuance under the ESPP as of October 31, 2022. The ESPP provides for 24-month offering periods beginning June 15 and December 15 of each year, and each offering period contains four six-month purchase periods. On each purchase date, ESPP participants will purchase shares of our Class A common stock at a price per share equal to 85% of the lesser of (1) the fair market value of the Class A common stock on the offering date or (2) the fair market value of the Class A common stock on the purchase date.

We estimated the fair value of ESPP purchase rights using a Black-Scholes option pricing model with the following assumptions:


	Nine Months Ended October 31,
	2022			2021
Fair value of common stock	$	8.91		$	16.07
Expected volatility	44.4% - 52.3%			41.8% - 53.2%
Expected term (years)	0.5 - 2.0			0.5 - 2.0
Risk-free interest rate	2.3% - 3.2%			0.1% - 0.2%
Expected dividend yield	—		%	—		%

Stock-based compensation expense was recorded in the following cost and expense categories in the accompanying unaudited condensed consolidated statements of comprehensive loss (in thousands):


	Three Months Ended October 31,				Nine Months Ended October 31,
	2022		2021		2022		2021
Cost of subscription revenue	$	2,437	$	1,580	$	6,517	$	4,157
Cost of professional services revenue	3,479		2,822		10,186		7,487
Research and development	7,536		5,774		20,967		15,546
Sales and marketing	10,188		6,298		27,603		15,993
General and administrative	5,367		3,438		14,772		8,595
Total stock-based compensation expense	$	29,007	$	19,912	$	80,045	$	51,778

As of October 31, 2022, unrecognized compensation costs related to unvested equity awards and the weighted-average remaining period over which those costs are expected to be recognized were as follows (dollars in thousands):