The Company’s equity incentive plans provide for granting various stock-based awards to eligible employees, non-employee directors, and consultants of the Company. In addition, the Company offers an employee stock purchase plan to eligible employees.

The Company recognized stock-based compensation expense for all equity arrangements as follows:


	Three Months Ended June 30,				Six Months Ended June 30,
	2024		2023		2024		2023
	(in thousands)
Cost of revenue:
Subscription	$	2,983	$	2,715	$	5,611	$	4,982
Services	451		323		863		632
Sales and marketing	8,285		9,076		14,674		16,575
Research and development	6,969		6,401		12,400		11,434
General and administrative	7,595		11,668		13,314		16,110
	$	26,283	$	30,183	$	46,862	$	49,733

The table below summarizes return target option activity for the six months ended June 30, 2024:


	Options	Weighted‑ Average Exercise Price		Weighted‑ Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value (in thousands)
Outstanding, December 31, 2023	2,594,622	$	6.61	4.3	$	29,697
Exercised	(102,763)	6.01			1,285
Outstanding, June 30, 2024	2,491,859	$	6.64	3.9	$	24,571
Options exercisable at June 30, 2024	2,491,859	$	6.64	3.9	$	24,571
Vested or expected to vest at June 30, 2024	2,491,859	$	6.64	3.9	$	24,571

The table below summarizes the service-based option activity for the six months ended June 30, 2024:


	Options	Weighted‑ Average Exercise Price		Weighted‑ Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value (in thousands)
Outstanding, December 31, 2023	1,048,885	$	5.54	3.2	$	13,129
Exercised	(200,875)	5.67			2,828
Outstanding, June 30, 2024	848,010	$	5.51	3.1	$	9,317
Options exercisable at June 30, 2024	848,010	$	5.51	3.1	$	9,317
Vested or expected to vest at June 30, 2024	848,010	$	5.51	3.1	$	9,317


	Units	Weighted-Average Grant Date Fair Value (per share)
Outstanding, December 31, 2023	10,551,679	$	24.49
Granted	4,984,772	17.72
Vested	(2,015,812)	25.08
Forfeited	(788,420)	24.61
Outstanding, June 30, 2024	12,732,219	$	21.74

RSUs under the 2020 Plan generally vest ratably on an annual basis over four years. There was $225.5 million of unrecognized compensation expense related to unvested RSUs that is expected to be recognized over a weighted-average period of 2.8 years as of June 30, 2024. The total fair value of RSUs vested during the six months ended June 30, 2024 was $50.6 million.

In connection with the Company’s former CEO Dean Hager’s Transition and Retirement Agreement, dated May 2, 2023, and his retirement effective September 1, 2023, the Company recognized $5.7 million of incremental stock-based compensation expense during the three months ended June 30, 2023 related to the modification of vested stock options and acceleration of expense of unvested RSUs through the retirement date.

As of June 30, 2024 and December 31, 2023, the Company withheld, at the employees’ request, $0.9 million and $1.0 million, respectively, of eligible employee compensation, which is included in accrued liabilities in the condensed consolidated balance sheets, for purchases of common stock under the 2021 ESPP.

As of June 30, 2024, 5,757,984 shares of common stock were reserved for future issuance under the 2021 ESPP. Activity under the 2021 ESPP for the six months ended June 30, 2024 was as follows:


Shares of common stock issued	209,047
Weighted-average purchase price per share	$	13.06
Total proceeds to the Company (in thousands)	$	2,729

The average grant date fair value for the offering period under the 2021 ESPP that commenced on May 1, 2024 was $5.06 per share. The Company used the following assumptions in the Black-Scholes option pricing model to estimate the fair value:


Expected term			0.5 years
Expected volatility			40.90%
Risk-free interest rate			5.43%
Expected dividend yield			—%

There was $0.6 million of unrecognized compensation expense related to the 2021 ESPP that is expected to be recognized over a period of four months as of June 30, 2024.