The Company maintains the 2013 Stock Incentive Plan (as amended, the “2013 Equity Plan”), under which the Company’s employees, officers, directors, and other eligible participants may be awarded various types of share-based compensation, including options to purchase shares of the Company’s class A common stock, restricted stock units, and other stock-based awards. As of March 31, 2023, a total of 2,750,000 shares of the Company’s class A common stock were authorized for issuance under the 2013 Equity Plan. As of March 31, 2023, there were 86,415 shares of class A common stock reserved and available for future issuance under the 2013 Equity Plan.

In April 2023, the Board of Directors authorized, subject to stockholder approval, the 2023 Equity Incentive Plan (the “2023 Equity Plan”), which is intended to replace the 2013 Equity Plan. If the Company’s stockholders approve the 2023 Equity Plan, the Company will not make any further grants under the 2013 Equity Plan following the date of such approval, though awards previously granted under the 2013 Equity Plan would remain outstanding.

Subject to stockholder approval of the 2023 Equity Plan, the 2023 Equity Plan will be effective for a period of ten years after stockholder approval and a total of 200,000 additional shares of the Company’s class A common stock will be authorized for issuance under the 2023 Equity Plan, plus a number of shares of the Company’s class A common stock (up to 1,732,703 shares) as is equal to the number of shares of the Company’s class A common stock reserved for issuance under the 2013 Equity Plan that remain available for grant immediately prior to the date that the 2023 Equity Plan is approved by the Company’s stockholders and the number of shares of the Company’s class A common stock subject to awards granted under the 2013 Equity Plan that are outstanding as of such date and which expire, terminate or are otherwise surrendered, cancelled or forfeited or repurchased by the Company at their original issuance price pursuant to a contractual repurchase right, including shares that are delivered (either by actual delivery, attestation or net exercise) to the Company by a participant to (i) purchase shares upon the exercise of such award or (ii) satisfy tax withholding obligations with respect to such awards, including shares retained from the award creating the tax obligation (subject, in the case of incentive stock options, to any limitations under the Internal Revenue Code of 1986, as amended).

As of March 31, 2023, there were options to purchase 1,520,079 shares of class A common stock outstanding under the 2013 Equity Plan.

The following table summarizes the Company’s stock option activity (in thousands, except per share data and years) for the three months ended March 31, 2023:


	Stock Options Outstanding
				Weighted Average		Aggregate		Weighted Average
				Exercise Price		Intrinsic		Remaining Contractual
	Shares			Per Share		Value		Term (Years)
Balance as of January 1, 2023		1,577		$	288.30
Granted		0		$	0
Exercised		(44	)	$	151.51	$	5,259
Forfeited/Expired		(13	)	$	477.02
Balance as of March 31, 2023		1,520		$	290.79
Exercisable as of March 31, 2023		900		$	236.00	$	110,740		4.1
Expected to vest as of March 31, 2023		620		$	370.35	$	28,301		8.4
Total		1,520		$	290.79	$	139,041		5.9

Stock options outstanding as of March 31, 2023 are comprised of the following range of exercise prices per share (in thousands, except per share data and years):


	Stock Options Outstanding at March 31, 2023
			Weighted Average		Weighted Average
			Exercise Price		Remaining Contractual
Range of Exercise Prices per Share	Shares		Per Share		Term (Years)
$121.43 - $200.00		873	$	137.87		3.9
$200.01 - $300.00		80	$	239.61		9.4
$400.01 - $500.00		317	$	408.73		8.8
$600.01 - $691.23		250	$	691.23		7.8
Total		1,520	$	290.79		5.9

An aggregate of 139,125 stock options with an aggregate grant date fair value of $41.4 million vested during the three months ended March 31, 2023. The weighted average grant date fair value of stock option awards using the Black-Scholes valuation model was $227.51 for each share subject to a stock option granted during the three months ended March 31, 2022 based on the following assumptions:

No stock option awards were granted during the three months ended March 31, 2023.

For the three months ended March 31, 2023 and 2022, the Company recognized approximately $12.9 million and $10.4 million, respectively, in share-based compensation expense from stock options granted under the 2013 Equity Plan. As of March 31, 2023, there was approximately $116.6 million of total unrecognized share-based compensation expense related to unvested stock options, which the Company expects to recognize over a weighted average vesting period of approximately 2.5 years.

As of March 31, 2023, there were 115,609 share-settled restricted stock units outstanding under the 2013 Equity Plan. The following table summarizes the Company’s share-settled restricted stock unit activity (in thousands) for the periods indicated:


	Share-Settled Restricted Stock Units Outstanding
				Aggregate
	Units			Intrinsic Value
Balance as of January 1, 2023		120
Granted		6
Vested		(6	)	$	1,598
Forfeited		(4	)
Balance as of March 31, 2023		116
Expected to vest as of March 31, 2023		116		$	33,795

During the three months ended March 31, 2023, 5,780 share-settled restricted stock units having an aggregate grant date fair value of $3.4 million vested, and 1,963 shares were withheld to satisfy tax obligations, resulting in 3,817 issued shares. The weighted average grant date fair value of share-settled restricted stock units granted during the three months ended March 31, 2023 and 2022 was $258.65 and $404.60, respectively, based on the fair value of the Company’s class A common stock. For the three months ended March 31, 2023 and 2022, the Company recognized approximately $3.4 million and $3.2 million, respectively, in share-based compensation expense from share-settled restricted stock units granted under the 2013 Equity Plan. As of March 31, 2023, there was approximately $34.5 million of total unrecognized share-based compensation expense related to unvested share-settled restricted stock units, which the Company expects to recognize over a weighted average vesting period of approximately 2.6 years.

From time to time the Company has granted “other stock-based awards” and “cash-settled restricted stock units” under the 2013 Equity Plan. Other stock-based awards are similar to stock options, and cash-settled restricted stock units are similar to the Company’s share-settled restricted stock units, except in each case these awards are settled in cash only and not in shares of the Company’s class A common stock. Due to their required cash settlement feature, these awards are classified as liabilities in the Company’s Consolidated Balance Sheets and the fair value of the awards is remeasured each quarterly reporting period. For the three months ended March 31, 2023 and 2022, the Company recognized approximately $0.7 million and $0.1 million, respectively, in share-based compensation expense from other stock-based awards and cash-settled restricted stock units. As of March 31, 2023, there was approximately $0.7 million of total unrecognized share-based compensation expense related to other stock-based awards and cash-settled restricted stock units, which the Company expects to recognize over a weighted average vesting period of approximately 1.9 years, subject to additional fair value adjustments through the earlier of settlement or expiration.

The Company also maintains the 2021 Employee Stock Purchase Plan (the “2021 ESPP”). The purpose of the 2021 ESPP is to provide eligible employees of the Company and certain of its subsidiaries with opportunities to purchase shares of the Company’s class A common stock in 6-month offering periods commencing on each March 1 and September 1. An aggregate of 100,000 shares of the Company’s class A common stock has been authorized for issuance under the 2021 ESPP. During the three months ended March 31, 2023, 12,672 shares of class A common stock were issued in connection with the 2021 ESPP. As of March 31, 2023, 66,791 shares of the Company’s class A common stock remained available for issuance under the 2021 ESPP.

For the three months ended March 31, 2023 and 2022, the Company recognized approximately $0.6 million and $0.6 million, respectively, in share-based compensation expense related to the 2021 ESPP. As of March 31, 2023, there was approximately $0.7 million of total unrecognized share-based compensation expense related to the 2021 ESPP, which the Company expects to recognize over a period of approximately 0.4 years.

The following table summarizes the tax (benefit) expense related to the Company’s equity plans (in thousands) for the three months ended March 31, 2023 and 2022:


	Three Months Ended
	March 31,
	2023			2022
Tax (benefit) expense related to:
Share-based compensation expense	$	(3,225	)	$	(2,897	)
Exercises of stock options and vesting of share-settled restricted stock units		(85	)		53
Total tax benefit related to the Company's equity plans	$	(3,310	)	$	(2,844	)