Our board of directors has authorized a share repurchase program of our Class A common stock, which commenced in January 2017 and does not have an expiration date. As of December 31, 2022, $10.87 billion remained available and authorized for repurchases under this program. In January 2023, an additional $40 billion of repurchases was authorized under this program. During the three months ended March 31, 2023, we repurchased and subsequently retired 56 million shares of our Class A common stock for an aggregate amount of $9.22 billion, including $77 million related to the 1% excise tax on net share repurchases as a result of the Inflation Reduction Act of 2022. As of March 31, 2023, $41.73 billion remained available and authorized for repurchases.

The timing and actual number of shares repurchased under the repurchase program depend on a variety of factors, including price, general business and market conditions, and other investment opportunities. Shares may be repurchased through open market purchases or privately negotiated transactions, including through the use of trading plans intended to qualify under Rule 10b5-1 under the Securities Exchange Act of 1934, as amended.

We have one active share-based employee compensation plan, the 2012 Equity Incentive Plan (Amended 2012 Plan), which was amended in each of June 2016, February 2018, and December 2022. Our Amended 2012 Plan provides for the issuance of incentive and nonqualified stock options, restricted stock awards, stock appreciation rights, RSUs, performance shares, and stock bonuses to qualified employees, directors, and consultants. Shares that are withheld in connection with the net settlement of RSUs or forfeited are added to the reserves of the Amended 2012 Plan.

Pursuant to the automatic increase provision under our Amended 2012 Plan, the number of shares reserved for issuance increases automatically on January 1 of each of the calendar years during the term of the Amended 2012 Plan, which will continue through April 2026, by a number of shares of Class A common stock equal to the lesser of (i) 2.5% of the total issued and outstanding shares of our Class A common stock as of the immediately preceding December 31st or (ii) a number of shares determined by our board of directors. Pursuant to this automatic increase provision, our board of directors approved an increase of 56 million shares of Class A common stock reserved for issuance, effective January 1, 2023.

In December 2022, our board of directors approved an amendment to our Amended 2012 Plan to increase the number of shares reserved for issuance under the Amended 2012 Plan by 425 million shares, effective March 1, 2023 (Plan Amendment). The Plan Amendment was also approved by holders of a majority of the voting power of our outstanding capital stock in December 2022. As of March 31, 2023, there were 458 million shares of our Class A common stock reserved for future issuance under our Amended 2012 Plan.

The following table summarizes our share-based compensation expense, which consists of the company's RSU expense, by line item in our condensed consolidated statements of income (in millions):


	Three Months Ended March 31,
	2023		2022
Cost of revenue	$	160	$	160
Research and development	2,449		1,941
Marketing and sales	219		216
General and administrative	223		181
Total share-based compensation expense	$	3,051	$	2,498


	Number of Shares	Weighted-Average Grant Date Fair Value Per Share
	(in thousands)
Unvested at December 31, 2022	127,110	$	216.93
Granted	105,156	$	196.27
Vested	(13,612)	$	211.80
Forfeited	(3,262)	$	229.43
Unvested at March 31, 2023	215,392	$	206.98

The fair value as of the respective vesting dates of RSUs that vested during the three months ended March 31, 2023 and 2022 was $2.44 billion and $2.43 billion, respectively. The income tax benefit recognized related to awards vested during the three months ended March 31, 2023 and 2022 was $519 million and $514 million, respectively.

As of March 31, 2023, there was $42.84 billion of unrecognized share-based compensation expense related to RSU awards. This unrecognized compensation expense is expected to be recognized over a weighted-average period of approximately three years based on vesting under the award service conditions. As a result of the 2023 Restructuring related to employees notified in April 2023, approximately 8 million of unvested RSUs as of March 31, 2023, are expected to be forfeited, and $1.57 billion of unrecognized share-based compensation expense related to these RSUs awards is not expected to be recognized.