Prior to its expiration, the Company maintained the 2013 Stock Incentive Plan (as amended, the “2013 Equity Plan”), under which the Company’s employees, officers, and directors were 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. In May 2023, the 2013 Equity Plan expired and no new awards may be granted under the 2013 Equity Plan, although awards previously granted under the 2013 Equity Plan will continue to remain outstanding in accordance with their terms.

The Company maintains the 2023 Equity Incentive Plan (the “2023 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, performance stock units, and other stock-based awards. An aggregate of up to 1,932,703 shares of the Company’s class A common stock were authorized for issuance under the 2023 Equity Plan.

As of June 30, 2024, there were 232,574 shares of class A common stock reserved and available for future issuance under the 2023 Equity Plan. The 2013 Equity Plan and the 2023 Equity Plan together are referred to herein as the “Stock Incentive Plans.”

As of June 30, 2024, there were options to purchase 591,555 shares of class A common stock outstanding under the Stock Incentive Plans.

The following table summarizes the Company’s stock option activity (in thousands, except per share data and years) for the six months ended June 30, 2024:


	Stock Options Outstanding
				Weighted Average		Aggregate		Weighted Average
				Exercise Price		Intrinsic		Remaining Contractual
	Shares			Per Share		Value		Term (Years)
Balance as of January 1, 2024		1,294		$	286.78
Granted		10		$	1,594.74
Exercised		(695	)	$	220.77	$	612,055
Forfeited/Expired		(17	)	$	447.47
Balance as of June 30, 2024		592		$	379.99
Exercisable as of June 30, 2024		302		$	344.16	$	312,250		6.2
Expected to vest as of June 30, 2024		290		$	417.41	$	279,809		7.7
Total		592		$	379.99	$	592,059		7.0

Stock options outstanding as of June 30, 2024 are comprised of the following range of exercise prices per share (in thousands, except per share data and years):


	Stock Options Outstanding at June 30, 2024
			Weighted Average		Weighted Average
			Exercise Price		Remaining Contractual
Range of Exercise Prices per Share	Shares		Per Share		Term (Years)
$124.48 - $200.00		180	$	155.97		5.6
$200.01 - $300.00		105	$	249.98		8.3
$300.01 - $400.00		3	$	301.63		8.9
$400.01 - $500.00		175	$	411.68		7.6
$600.01 - $700.00		120	$	691.23		6.7
$1,500.01 - $1,599.29		9	$	1,594.74		9.7
Total		592	$	379.99		7.0

An aggregate of 138,465 stock options with an aggregate grant date fair value of $37.5 million vested during the six months ended June 30, 2024. The weighted average grant date fair value of stock option awards using the Black-Scholes valuation model was $1,112.28 and $190.86 for each share subject to a stock option granted during the six months ended June 30, 2024 and 2023, respectively, based on the following assumptions:

For the three and six months ended June 30, 2024, the Company recognized approximately $10.3 million and $20.1 million, respectively, in share-based compensation expense from stock options granted under the Stock Incentive Plans. For the three and six months ended June 30, 2023, the Company recognized approximately $10.5 million and $23.4 million, respectively, in share-based compensation expense from stock options granted under the Stock Incentive Plans. As of June 30, 2024, there was approximately $56.8 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 1.9 years.

As of June 30, 2024, there were 163,868 share-settled restricted stock units outstanding under the Stock Incentive Plans. 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, 2024		185
Granted		31
Vested		(37	)	$	56,160
Forfeited		(15	)
Balance as of June 30, 2024		164
Expected to vest as of June 30, 2024		164		$	225,725

During the six months ended June 30, 2024, 37,458 share-settled restricted stock units having an aggregate grant date fair value of $11.7 million vested, and 2,506 shares were withheld to satisfy tax obligations, resulting in 34,952 issued shares. In the second quarter of 2024, the Company transitioned from a “net settlement” approach, which it previously used in nearly all jurisdictions in which restricted stock units were granted, to generally using a “sell-to-cover” approach for settling its share-settled restricted stock units. Under a “net settlement” approach, when settling restricted stock units, the Company withholds shares equal in value to the statutory withholding obligations and pays the tax withholding amount from its own cash reserves. Under a “sell-to-cover” approach, shares underlying vested awards are issued in full and participants sell shares in the market in amounts necessary to satisfy statutory withholding obligations. The tax withholding obligations are therefore satisfied with proceeds from these sales rather than from the Company’s cash reserves. During the six months ended June 30, 2023, 12,847 share-settled restricted stock units having an aggregate grant date fair value of $5.1 million vested, and 2,792 shares were withheld to satisfy tax obligations, resulting in 10,055 issued shares. The weighted average grant date fair value of share-settled restricted stock units granted during the six months ended June 30, 2024 and 2023 was $1,452.21 and $277.59, respectively, based on the fair value of the Company’s class A common stock.

For the three and six months ended June 30, 2024, the Company recognized approximately $7.4 million and $12.1 million, respectively, in share-based compensation expense from share-settled restricted stock units granted under the Stock Incentive Plans. For the three and six months ended June 30, 2023, the Company recognized approximately $3.9 million and $7.3 million, respectively, in share-based compensation expense from share-settled restricted stock units granted under the Stock Incentive Plans. As of June 30, 2024, there was approximately $77.5 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 3.1 years.

As of June 30, 2024, there were 30,285 performance stock units outstanding under the 2023 Equity Plan. The following table summarizes the Company’s performance stock unit activity (in thousands) for the periods indicated:


	Share-Settled Performance Stock Units Outstanding
				Aggregate
	Units			Intrinsic Value
Balance as of January 1, 2024		25
Granted		6
Vested		0		$	0
Forfeited		(1	)
Balance as of June 30, 2024		30
Expected to vest as of June 30, 2024		30		$	83,434

The weighted average grant date fair value of performance stock units using the Monte-Carlo simulation model was $3,071.27 and $486.18 for each performance stock unit granted during the six months ended June 30, 2024 and 2023, respectively, based on the following assumptions:


	Six Months Ended
	June 30,
	2024			2023
Expected term of awards in years		3.0			3.0
Expected volatility		92.7	%		95.6	%
Risk-free interest rate		4.4	%		4.1	%
Expected dividend yield		0.0	%		0.0	%

No performance stock units vested during the six months ended June 30, 2024 and 2023. For the three and six months ended June 30, 2024, the Company recognized approximately $2.4 million and $3.5 million, respectively, in share-based compensation expense from performance stock units granted under the 2023 Equity Plan. For the three and six months ended June 30, 2023, the Company recognized approximately $0.3 million and $0.3 million, respectively, in share-based compensation expense from performance stock units granted under the 2023 Equity Plan. As of June 30, 2024, there was approximately $23.4 million of total unrecognized share-based compensation expense related to unvested performance stock units, which the Company expects to recognize over a weighted average vesting period of approximately 2.5 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 and six months ended June 30, 2024, the Company recognized approximately $0.1 million and $1.9 million, respectively, in share-based compensation expense from other stock-based awards and cash-settled restricted stock units. For the three and six months ended June 30, 2023, the Company recognized approximately $0.4 million and $1.1 million, respectively, in share-based compensation expense from other stock-based awards and cash-settled restricted stock units. As of June 30, 2024, there was approximately $0.4 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 0.6 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 six months ended June 30, 2024, 6,932 shares of class A common stock were issued in connection with the 2021 ESPP. As of June 30, 2024, 52,675 shares of the Company’s class A common stock remained available for issuance under the 2021 ESPP.

For the three and six months ended June 30, 2024, the Company recognized approximately $0.4 million and $0.8 million, respectively, in share-based compensation expense related to the 2021 ESPP. For the three and six months ended June 30, 2023, the Company recognized approximately $0.4 million and $1.0 million, respectively, in share-based compensation expense related to the 2021 ESPP. As of June 30, 2024, there was approximately $0.3 million of total unrecognized share-based compensation expense related to the 2021 ESPP, which the Company expects to recognize over a period of approximately 0.2 years.

The following table summarizes the tax (benefit) expense related to the Company’s equity plans (in thousands) for the three and six months ended June 30, 2024 and 2023:


	Three Months Ended						Six Months Ended
	June 30,						June 30,
	2024			2023			2024			2023
Tax (benefit) expense related to:
Share-based compensation expense	$	(3,887	)	$	(2,754	)	$	(8,079	)	$	(5,979	)
Exercises of stock options and vesting of share-settled restricted stock units		(52,960	)		370			(157,266	)		285
Total tax benefit related to the Company's equity plans	$	(56,847	)	$	(2,384	)	$	(165,345	)	$	(5,694	)