The Company recorded equity-based compensation in the following expense categories in the consolidated statements of operations and comprehensive income (loss) in 2024 and 2023 (in thousands):


	2024		2023
General and administrative	$	22,677	$	18,270
Research and development		15,147		12,168
Total equity-based compensation	$	37,824	$	30,438

Cullinan grants equity awards in the form of stock options and RSUs to its employees and non-employees directors, through the 2021 Stock Option and Incentive Plan (the "2021 Stock Plan"). Cullinan has also granted equity awards outside of the 2021 Stock Plan in the form of stock options as an inducement material to an individual's entering into employment with the Company. As of December 31, 2024, there were approximately 2.0 million shares remaining for future grants under the 2021 Stock Plan.

The 2021 Stock Plan provides that the number of shares reserved and available for issuance under the 2021 Stock Plan will automatically increase each January 1 by 5% of the outstanding number of shares of Cullinan’s common stock on the immediately preceding December 31 or such lesser number of shares as determined by Cullinan’s board of directors or compensation committee. On January 1, 2025, the total number of shares available for issuance under the 2021 Stock Plan increased by approximately 2.9 million shares under this provision.

The options granted have a ten-year term and were issued with an exercise price equal to the closing market price of Cullinan’s common stock on the grant date. For equity awards with service-based vesting conditions, Cullinan recognizes compensation expense over the vesting period, which is generally over a four-year period. For equity awards with a market-based vesting condition, the Company recognizes compensation expense over the requisite service period. The number of shares awarded, if any, when a market-based award vests will depend on the degree of achievement of the corporate stock price metrics within the performance period of the award.

The fair value of options is estimated using the Black-Scholes option pricing model, which takes into account inputs such as the exercise price, the value of the underlying common stock at the grant date, expected term, expected volatility, risk-free interest rate and dividend yield. The fair value of each grant of options during 2024 and 2023 were determined using the methods and assumptions discussed below:

For 2024 and 2023, the weighted-average grant date fair value of the options granted were $12.28 and $7.70 per share, respectively. The grant date fair value was estimated at the time of grant using the Black-Scholes option-pricing model using the following weighted-average assumptions in 2024 and 2023:


	2024			2023
Risk-free interest rate		4.2	%		4.0	%
Expected term (in years)		6.0			6.0
Expected volatility		70.3	%		78.7	%
Expected dividend yield		0.0	%		0.0	%

The following table summarizes 2024 stock option activity (options and aggregate intrinsic value in thousands):


	Number of Options			Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term (in Years)		Aggregate Intrinsic Value
Outstanding as of December 31, 2023		10,539		$	15.46
Granted		2,996		$	18.66
Exercised		(935	)	$	8.18
Forfeited		(967	)	$	23.15
Outstanding as of December 31, 2024		11,633		$	16.35		7.53	$	11,987
Exercisable as of December 31, 2024		6,693		$	16.10		6.88	$	10,368

As of December 31, 2024 there was $51.4 million in unrecognized compensation costs that are expected to be recognized over a remaining weighted-average period of 2.4 years.

The aggregate intrinsic value of options is calculated as the difference between the exercise price of the options and the fair value of Cullinan’s common stock for those options that had exercise prices lower than the fair value of the Company’s common stock at the measurement date. The total intrinsic value of options exercised in 2024 and 2023 was $10.4 million and $0.3 million, respectively.

The following table summarizes the activity related to RSUs during 2024 (shares in thousands):


	Number of Shares			Weighted-Average Grant Date Fair Value
Outstanding unvested as of December 31, 2023		804		$	11.98
Granted		836		$	17.54
Vested		(219	)	$	12.29
Forfeited		(124	)	$	14.84
Outstanding unvested as of December 31, 2024 (1)		1,297		$	15.24

(1)

The number outstanding represents the number of shares issuable upon vesting of service-based and market-based RSUs, assuming the Company achieves its corporate stock price metrics at the target achievement level.

As of December 31, 2024, there was $14.3 million in unrecognized compensation cost related to RSUs expected to be recognized over a remaining weighted-average period of 2.4 years. The total fair value of RSUs that vested during 2024 and 2023 was $2.9 million and $1.7 million, respectively.

The 2021 Employee Stock Purchase Plan (the "ESPP") authorizes the issuance of shares of common stock to participating eligible employees and provides for two six-month offering periods each year. As of December 31, 2024, there were approximately 1.6 million shares remaining for future purchases under the ESPP.

The ESPP provides that the number of shares reserved and available for issuance under the ESPP will automatically increase each January 1 by the lesser of 0.8 million shares of the Company's common stock, 1% of the outstanding number of shares of Cullinan’s common stock on the immediately preceding December 31, or such lesser number of shares as determined by the Company’s compensation committee. On January 1, 2025, the total number of shares available for issuance under the ESPP increased by approximately 0.6 million shares under this provision.

During each of 2024 and 2023, Cullinan issued less than 0.1 million shares of its common stock pursuant the ESPP.