The board of directors was authorized to grant stock-based awards under the 2015 Equity Incentive Plan (the “2015 Plan”). Following the effectiveness of the 2020 Plan (as defined below), the 2015 Plan was terminated. However, any outstanding awards granted under the 2015 Plan will remain outstanding, subject to the terms of the 2015 Plan and applicable award agreement. Shares of Class A common stock subject to awards granted under the 2015 Plan that expire unexercised or are cancelled, terminated or forfeited in any manner without issuance of shares thereunder following the effective date of the 2020 Plan, have or will become available for issuance under the 2020 Plan in accordance with its terms.

In connection with our IPO in 2020, our board of directors adopted, and our stockholders approved, the 2020 Incentive Award Plan (the “2020 Plan”), which provides for the grant of stock options, including incentive stock options, and nonqualified stock options, restricted stock, dividend equivalents, RSUs, stock appreciation rights, and other stock or cash based awards to our employees, consultants and directors. The board of directors or its compensation committee is authorized to grant stock-based awards under the 2020 Plan, which may be issued as awards covering either Class A or Class B common stock. Notwithstanding anything to the contrary in the 2020 Plan, no more than 300.0 million shares of common stock (either Class A or Class B common stock) may be issued pursuant to the exercise of incentive stock options under the 2020 Plan.

The number of shares available for issuance under the 2020 Plan will increase annually on the first day of each calendar year beginning January 1, 2021 and ending on and including January 1, 2030, equal to the lesser of (i) 5% of the aggregate number of shares of Class A and Class B common stock outstanding on the final day of the immediately preceding calendar year and (ii) such smaller number of shares as is determined by our board of directors.

At December 31, 2022, 52.9 million shares were available for issuance under the 2020 Plan.

In connection with our IPO in 2020, our board of directors adopted, and our stockholders approved, the 2020 Employee Stock Purchase Plan ("ESPP"). A total of 9.0 million shares of Class A common stock were initially reserved for issuance under the ESPP. In addition, the number of shares available for issuance under the ESPP will increase annually on January 1 of each calendar year beginning in 2021 and ending in 2030, by an amount equal to the lesser of: (i) 1% of the aggregate number of shares of Class A and Class B common stock outstanding on the final day of the immediately preceding calendar year and (ii) such smaller number of shares as is determined by our board of directors. In no event will more than 100.0 million shares of Class A common stock be available for issuance under the ESPP.

The ESPP allows eligible employees to purchase our common stock, through payroll deductions, at 85% of the lower of the fair market value of Class A common stock on the first trading day of the offering period or on the applicable purchase date, which will be the final trading day of the applicable purchase period. The ESPP is intended to qualify as an employee stock purchase plan under the IRS Code Section 423.

At December 31, 2022, 16.9 million shares were available for issuance under the ESPP. At December 31, 2022, there were no employee stock purchase offerings since the adoption and approval of the ESPP.

Stock options granted generally vest 25% of the total award on the first anniversary of the vesting commencement date, and thereafter ratably monthly over the remaining three-year period. Stock options generally have a ten-year term. Stock options granted under the 2015 Plan and 2020 Plan do not include any forfeitable or non-forfeitable dividend equivalent rights.

A summary of the stock option activity is as follows:


						Weighted
				Weighted		Average
				Average		Remaining	Aggregate
				Exercise		Contractual	Intrinsic
(in thousands, except per share amounts and term information)	Shares			Price		Term	Value
Outstanding at December 31, 2021		13,568		$	7.55	7.3 years	$	341,929
Granted		7,580			8.09
Exercised		(2,192	)		4.16
Expired / Cancelled / Forfeited		(1,691	)		12.64
Outstanding at December 31, 2022		17,265		$	7.72	7.3 years	$	5,321
Exercisable at December 31, 2022		7,949		$	6.60	5.4 years	$	5,321

The weighted average grant date fair value per share of stock options granted for the years ended December 31, 2022, 2021 and 2020 was $5.41, $18.81 and $4.23, respectively. The aggregate intrinsic value of options exercised for the years ended December 31, 2022, 2021 and 2020 was $18.2 million, $244.4 million and $112.7 million, respectively. The fair value of stock options that vested during the years ended December 31, 2022, 2021 and 2020 was $14.6 million, $15.3 million and $10.2 million, respectively.

All stock options outstanding at December 31, 2022 were options to purchase shares of Class A common stock. The fair value of option awards issued with service or performance vesting conditions are estimated on the grant date using the Black-Scholes option pricing model. The following table summarizes the assumptions used:


	Year Ended December 31,
	2022		2021		2020
Risk-free interest rate	1.7% - 3.8%		0.9% - 1.3%		0.4% - 1.4%
Expected term	5.7 - 6.1 years		5.7 - 6.1 years		5.3 - 6.3 years
Expected stock price volatility	60% - 77.5%		57.5% - 60%		50% - 62%
Dividend yield		—		—		—
Fair value of common stock per share	$5.25 - $22.02		$16.79 - $24.48		$5.94 - $33.00

For the years ended December 31, 2022, 2021 and 2020, the stock-based compensation expense related to stock options was $12.7 million, $14.3 million and $13.0 million, respectively. At December 31, 2022, there was $43.1 million of total unrecognized stock-based compensation cost related to stock options, which is expected to be recognized over a weighted average remaining service period of 2.9 years.

A summary of the Restricted Stock Awards and Restricted Stock Unit activity is as follows:


	Restricted			Restricted Stock Units for Class A			Restricted Stock Units for Class B			Weighted Average
	Stock			Common			Common			Grant Date
(in thousands, except per share amounts)	Awards			Stock			Stock			Fair Value
Nonvested restricted stock awards or restricted stock units at December 31, 2021		939			4,431			5,645		$	29.64
Granted		—			19,643			—			7.76
Vested		(470	)		(2,664	)		(2,053	)		23.42
Forfeited		—			(2,949	)		—			16.67
Nonvested restricted stock awards or restricted stock units at December 31, 2022		469			18,461			3,592		$	13.69

For the years ended December 31, 2022, 2021 and 2020, the fair value of RSAs and RSUs that vested was $121.5 million, $95.8 million and $335.4 million, respectively.

The nonvested RSAs as of December 31, 2022 were originally granted in 2019 with a weighted average grant date fair value per share of $3.88. These RSAs vest on an annual basis in equal installments upon continued service over a four-

year period. The unrecognized stock-based compensation cost at December 31, 2022 related to these RSAs is expected to be fully recognized in 2023.

In connection with and subsequent to our IPO, we have granted RSUs for Class A common stock. Substantially all of the RSUs granted vest upon continued service over a four-year period. For the years ended December 31, 2022, 2021 and 2020, total stock-based compensation expense related to RSUs was $61.2 million, $53.5 million and $9.5 million, respectively. At December 31, 2022, there was $182.6 million of total unrecognized stock-based compensation cost related to these RSUs, which is expected to be recognized over a weighted average remaining service period of 3.3 years.

In September 2020, our board of directors granted RSUs covering an aggregate of 24.6 million shares of Class B common stock to our Co-Chief Executive Officers (the “Founders Awards”), subject to the completion of our IPO and continued employment through the applicable vesting dates. Each of our Co-Chief Executive Officers received (i) 8.2 million RSUs that vest based on the achievement of stock price goals ranging from $6.07 per share to $51.28 per share, (the “Performance-Vesting Founders Awards”) and (ii) 4.1 million RSUs that vest and settle in equal quarterly installments over four years, subject to certain vesting acceleration terms (the “Time-Vesting Founders Awards”). The grant date fair value of these awards totaled $533.3 million.

We used a Monte Carlo simulation model to calculate the grant date fair value of the Performance-Vesting Founders Awards and the derived service period. The Monte Carlo simulation model incorporates the likelihood of achieving the market condition and requires the input of assumptions including the estimated fair value of common stock, expected volatility, expected term, risk-free rate and dividend yield. We then applied a DLOM to the value of the RSUs as the issuance of the shares for these awards was deferred by three-years from the applicable vesting date, or earlier, upon a qualifying change in control or to satisfy tax withholding requirements. We utilized the Finnerty Model to calculate the DLOM using inputs, including length of holding period, volatility and dividend yield.

All of the Performance-Vesting Founders Awards vested in 2020, and we settled 0.7 million RSUs at that time which were sufficient to satisfy certain tax withholding obligations due in the year of vesting as allowed under the terms and conditions of the agreements governing the Founders Awards. There are no risks of forfeiture after the Performance-Vesting Founders Awards vested in 2020. As stipulated in the agreements governing the Founders Awards, the remaining 15.7 million Performance-Vesting Founders Awards shares will not be settled until three years from the applicable vesting date, or October 2023, or earlier upon a change in control event, as defined in the agreements governing the Founders Awards.

During the years ended December 31, 2022, 2021 and 2020, we recognized $44.5 million, $90.9 million and $373.0 million of stock-based compensation expense, respectively, related to the Founders Awards. At December 31, 2022, we recognized a cumulative $508.4 million of stock-based compensation expense related to the Founders Awards, of which $188.6 million related to the Time-Vesting Founders Awards and $319.8 million related to the Performance-Vesting Founders Awards. At December 31, 2022, there was $24.9 million of total unrecognized stock-based compensation cost related to the Time-Vesting Founders Awards, of which $20.5 million and $4.4 million are expected to be recognized in 2023 and 2024, respectively.