Our stock plans include the Alphabet Amended and Restated 2021 Stock Plan ("Alphabet 2021 Stock Plan") and Other Bets stock-based plans. Under our stock plans, RSUs and other types of awards may be granted. Under the Alphabet 2021 Stock Plan, an RSU award is an agreement to issue shares of our Class C stock at the time the award vests. RSUs generally vest over four years contingent upon employment on the vesting date.

As of December 31, 2023, there were 723 million shares of Class C stock reserved for future issuance under the Alphabet 2021 Stock Plan.

For the years ended December 31, 2021, 2022, and 2023, total SBC expense was $15.7 billion, $19.5 billion, and $22.1 billion, including amounts associated with awards we expect to settle in Alphabet stock of $15.0 billion, $18.8 billion, and $21.7 billion, respectively.

During the year ended December 31, 2023, total SBC expense includes $432 million associated with workforce reduction costs. See Note 8 for further details.

For the years ended December 31, 2021, 2022, and 2023, we recognized tax benefits on total SBC expense, which are reflected in the provision for income taxes in the Consolidated Statements of Income, of $3.1 billion, $3.9 billion, and $4.5 billion, respectively.

For the years ended December 31, 2021, 2022, and 2023, tax benefit realized related to awards vested or exercised during the period was $5.9 billion, $4.7 billion, and $5.6 billion, respectively. These amounts do not include the indirect effects of stock-based awards, which primarily relate to the R&D tax credit.

The following table summarizes the activities for unvested Alphabet RSUs for the year ended December 31, 2023 (in millions, except per share amounts):


	Unvested Restricted Stock Units
	Number of Shares	Weighted- Average Grant-Date Fair Value
Unvested as of December 31, 2022	324	$	107.98
Granted	263	$	97.59
Vested	(217)	$	100.36
Forfeited/canceled	(32)	$	106.56
Unvested as of December 31, 2023	338	$	104.93

The weighted-average grant-date fair value of RSUs granted during the years ended December 31, 2021 and 2022 was $97.46 and $127.22, respectively. Total fair value of RSUs, as of their respective vesting dates, during the years ended December 31, 2021, 2022, and 2023, were $28.8 billion, $23.9 billion, and $26.6 billion, respectively.