Stock-Based Plans and Compensation

9 Months Ended

Sep. 30, 2025

Share-Based Payment Arrangement [Abstract]

18. STOCK-BASED PLANS AND COMPENSATION

There were no stock-based compensation expenses related to the 2013 Plan in the three and nine months ended September 30, 2025 and 2024. Total stock-based compensation expense related to the 2017 Plan was as follows:


	Three Months Ended September 30,
	2025						2024
	Options		RSUs		Total		Options		RSUs		SARs		Total
Cost of revenue	$	197	$	868	$	1,065	$	285	$	1,057	$	—	$	1,342
Selling, general and administrative expense		233		7,922		8,155		499		7,607		2,315		10,421
Total	$	430	$	8,790	$	9,220	$	784	$	8,664	$	2,315	$	11,763

	Nine Months Ended September 30,
	2025						2024
	Options		RSUs		Total		Options		RSUs		SARs		Total
Cost of revenue	$	596	$	3,910	$	4,506	$	914	$	2,539	$	—	$	3,453
Selling, general and administrative expense		736		28,535		29,271		2,074		22,443		6,896		31,413
Total	$	1,332	$	32,445	$	33,777	$	2,988	$	24,982	$	6,896	$	34,866

As of September 30, 2025 and September 30, 2024, there was $56.0 million and $99.4 million, respectively, of total unrecognized stock-based compensation expense related to unvested options, restricted stock and SARs granted under the Plans. Such unrecognized expense is expected to be recognized over a weighted-average 1.9 year period. The 2021 Performance SARs were cancelled effective as of December 31, 2024, and as such, there was no related expense in the three and nine months ended September 30, 2025.

Montrose Amended & Restated 2017 Stock Incentive Plan

Restricted Stock Awards and Restricted Stock Units

RSAs and RSUs activity was as follows:


	Nine Months Ended September 30,
	2025					2024
	Shares			Weighted-Average Grant Date Fair Value		Shares			Weighted-Average Grant Date Fair Value
Beginning outstanding shares		2,617,059					2,468,722
Granted		1,350,599		$	18.02		354,060		$	40.12
Forfeited/ cancelled		(104,996	)	$	28.44		(43,115	)	$	36.70
Vested		(617,957	)	$	27.21		(150,641	)	$	37.46
Ending outstanding shares		3,244,705					2,629,026

Options

The following summarizes the options activity of the 2017 Plan:


	Options to Purchase Common Stock			Weighted-Average Exercise Price per Share		Weighted Average Grant Date Fair Value per Share		Weighted Average Remaining Contract Life (in Years)		Aggregate Intrinsic Value of In-The-Money Options
Outstanding as of December 31, 2023		2,516,272		$	30.92	$	15.95		7.0	$	13,825
Forfeited/ cancelled		(71,915	)		38.64		—		—		—
Expired		(20,510	)		45.57		—		—		—
Exercised		(51,524	)		26.21		—		—		732
Outstanding as of September 30, 2024		2,372,323		$	30.66	$	16.30		6.3	$	7,517
Outstanding as of December 31, 2024		2,345,207		$	30.62		16.32		6.0		776
Forfeited/ cancelled		(40,368	)		41.50		—		—		—
Expired		(65,287	)		36.89		—		—		—
Exercised		(16,804	)		15.45		—		—		164
Outstanding as of September 30, 2025		2,222,748		$	30.35	$	16.32		5.2	$	8,241
Exercisable as of September 30, 2025		1,995,520		$	29.11				5.1	$	8,241

Stock Appreciation Rights— As of September 30, 2024, there were 3,000,000 2021 Performance SARs outstanding under the 2017 Plan. These SARs represented the right to receive, upon exercise, a payment equal to the excess of (a) the fair market value of one share of the Company’s common stock, over (b) an exercise price of $66.79, payable, at the Company’s election, in cash or shares of common stock. The 2021 Performance SARs were cancelled effective December 31, 2024 and all remaining unamortized expense was recognized at the effective time of cancellation.

Montrose Amended & Restated 2013 Stock Option Plan

The following summarizes the activity of the 2013 Plan:


	Options to Purchase Common Stock			Weighted-Average Exercise Price per Share		Weighted Average Grant Date Fair Value per Share		Weighted Average Remaining Contract Life (in Years)		Aggregate Intrinsic Value of In-The-Money Options
Outstanding as of December 31, 2023		792,191		$	6.40	$	2.16		2.4	$	20,380
Exercised		(105,453	)		5.86		—		—		—
Outstanding as of September 30, 2024		686,738		$	6.49	$	2.49		1.8	$	13,606
Outstanding as of December 31, 2024		680,889		$	6.49		2.51		1.5		8,211
Expired		(1,000	)		6.03		—		—		—
Exercised		(18,095	)		8.02		—		—		309
Outstanding as of September 30, 2025		661,794		$	6.46	$	2.51		0.8	$	10,351
Exercisable as of September 30, 2025		661,794		$	6.45				0.8	$	10,351

Common Stock Reserved for Future Issuances—The Company has reserved certain stock of its authorized but unissued common stock for possible future issuance in connection with the following:


	September 30,
	2025		2024
Montrose 2013 Stock Incentive Plan		661,794		686,738
Montrose 2017 Stock Incentive Plan(1)		7,384,230		9,653,054
		8,046,024		10,339,792

(1) In January 2025 and 2024, the Board of Directors ratified the addition of 1,372,373 and 1,207,563 shares of common stock, respectively, to the number of shares available for issuance under the 2017 Plan pursuant to the annual increase provision of such plan. Unless the Board of Directors determines otherwise, additional annual increases will be effective on each January 1, through January 1, 2027. The 2017 Plan permits the company to settle awards, if and when vested, in cash at its discretion. Pursuant to the terms of the 2017 Plan, the number of shares authorized for issuance thereunder will only be reduced with respect to shares of common stock actually issued upon exercise or settlement of an award. Shares of common stock subject to awards that have been canceled, expired, forfeited or otherwise not issued under an award and shares of common stock subject to awards settled in cash do not count as shares of common stock issued under the 2017 Plan. The Company expects to have sufficient shares available under the 2017 Plan to satisfy the future settlement of outstanding awards. Shares reserved for future issuance as of September 30, 2024 include 3,000,000 shares underlying the 3,000,000 2021 Performance SARs, which were cancelled effective as of December 31, 2024.