We maintain three share-based employee compensation plans: the 2017 Equity Incentive Plan (“2017 Plan”), the 2014 Equity Incentive Plan (“2014 Plan”), and the 2012 Equity Incentive Plan (“2012 Plan”, and collectively with the 2017 Plan and the 2014 Plan, the “Stock Plans”). The 2017 Plan serves as the successor to the 2014 Plan and 2012 Plan and provides for the grant of incentive stock options to employees, including employees of any parent or subsidiary, and for the grant of nonstatutory stock options, stock appreciation rights, RSAs, RSUs, performance stock awards, performance cash awards, and other forms of stock awards to employees, directors, and consultants, including employees and consultants of our affiliates.

The following table summarizes the RSU and RSA activity during the nine months ended September 30, 2022:

	Class A Outstanding			Weighted- Average Grant Date Fair Value
	(in thousands, except per share data)
Unvested at December 31, 2021		86,180		$	26.07
Granted		67,165		$	18.88
Vested		(40,756	)	$	20.81
Forfeited		(18,446	)	$	26.00
Unvested at September 30, 2022		94,143		$	23.23

All RSUs and RSAs vest on the satisfaction of a service-based condition. Total unrecognized compensation cost related to outstanding RSUs and RSAs was $1.8 billion as of September 30, 2022 and is expected to be recognized over a weighted-

average period of 1.6 years. The service condition for RSUs and RSAs granted prior to February 2018 is generally satisfied over four years, 10% after the first year of service, 20% over the second year, 30% over the third year, and 40% over the fourth year. In limited instances, we have issued RSUs with vesting periods in excess of four years. The service condition for RSUs and RSAs granted after February 2018 is generally satisfied in equal monthly or quarterly installments over three to four years.

The following table summarizes the stock option award activity under the Stock Plans during the nine months ended September 30, 2022:

	Class A Number of Shares			Class B Number of Shares			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value ⁽¹⁾
	(in thousands, except per share data)
Outstanding at December 31, 2021		3,676			628		$	10.59		4.19	$	157,374
Granted		119			—		$	15.03		—	$	—
Exercised		(286	)		(10	)	$	13.13		—	$	—
Forfeited		(43	)		—		$	12.82		—	$	—
Outstanding at September 30, 2022		3,466			618		$	10.51		3.38	$	11,250

Total unrecognized compensation cost related to unvested stock options was $1.1 million as of September 30, 2022 and is expected to be recognized over a weighted-average period of 1.3 years.

	Three Months Ended September 30,				Nine Months Ended September 30,
	2022		2021		2022		2021
	(in thousands)
Cost of revenue	$	2,745	$	9,132	$	8,040	$	14,635
Research and development		246,783		198,893		651,299		537,177
Sales and marketing		43,098		51,675		133,746		118,250
General and administrative		50,333		41,198		144,128		124,509
Total	$	342,959	$	300,898	$	937,213	$	794,571

In July 2022, our board of directors authorized a stock repurchase program of up to $500.0 million of our Class A common stock, which was completed in the third quarter of 2022. During the three months ended September 30, 2022, we repurchased 51.3 million shares of our Class A common stock under the program for an aggregate of $500.5 million, representing the entire amount approved by our board of directors and including costs associated with the repurchases. These shares are recorded as treasury stock on our consolidated balance sheets.