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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM 10-Q

(Mark One)

☒ | QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended September 30, 2025

OR

☐ | TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from to

Commission File Number: 001-39394

Montrose Environmental Group, Inc.

(Exact Name of Registrant as Specified in its Charter)

Delaware | 46-4195044
( State or other jurisdiction of incorporation or organization) | (I.R.S. Employer Identification No.)
5120 Northshore Drive, North Little Rock, Arkansas | 72118
(Address of principal executive offices) | (Zip Code)

Registrant’s telephone number, including area code: (501) 900-6400

Securities registered pursuant to Section 12(b) of the Act:

Title of each class |  | Trading Symbol(s) |  | Name of each exchange on which registered
Common Stock, par value $0.000004 per share |  | MEG |  | The New York Stock Exchange

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒ No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Large accelerated filer |  | ☒ |  | Accelerated filer |  | ☐
Non-accelerated filer |  | ☐ |  | Smaller reporting company |  | ☐
Emerging growth company |  | ☐ |  |  |  |

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ☒

As of October 31, 2025, the registran t had 35,337,667 shares of common stock, $0.000004 par value per share, outstanding.

Table of Contents

|  | Page
PART I. | FINANCIAL INFORMATION |
Item 1. | Financial Statements | 1
| Unaudited Condensed Consolidated Statements of Financial Position | 1
| Unaudited Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) | 2
| Unaudited Condensed Consolidated Statements of Convertible and Redeemable Series A-2 Preferred Stock and Stockholders’ Equity | 3
| Unaudited Condensed Consolidated Statements of Cash Flows | 5
| Notes to Unaudited Condensed Consolidated Financial Statements | 7
Item 2. | Management’s Discussion and Analysis of Financial Condition and Results of Operations | 28
Item 3. | Quantitative and Qualitative Disclosures About Market Risk | 37
Item 4. | Controls and Procedures | 37
PART II. | OTHER INFORMATION |
Item 1. | Legal Proceedings | 39
Item 1A. | Risk Factors | 39
Item 2. | Unregistered Sales of Equity Securities and Use of Proceeds | 39
Item 3. | Defaults Upon Senior Securities | 39
Item 4. | Mine Safety Disclosures | 39
Item 5. | Other Information | 39
Item 6. | Exhibits | 40
Signatures | 41

i

PART I—FINANCI AL INFORMATION

Item 1. Financi al Statements.

MONTROSE ENVIRONMENTAL GROUP, INC.

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF FINANCIAL POSITION

(In thousands, except share data)

|  | September 30, |  |  | December 31, |
|  | 2025 |  |  | 2024 |
Assets |  |  |  |  |  |
Current assets |  |  |  |  |  |
Cash, cash equivalents and restricted cash |  | $ | 6,736 |  |  | $ | 12,935 |
Accounts receivable, net |  |  | 165,314 |  |  |  | 158,883 |
Contract assets |  |  | 68,743 |  |  |  | 52,091 |
Prepaid and other current assets |  |  | 15,185 |  |  |  | 14,090 |
Total current assets |  |  | 255,978 |  |  |  | 237,999 |
Non-current assets |  |  |  |  |  |
Property and equipment, net |  |  | 62,952 |  |  |  | 63,776 |
Operating lease right-of-use asset, net |  |  | 34,850 |  |  |  | 39,755 |
Finance lease right-of-use asset, net |  |  | 24,489 |  |  |  | 19,643 |
Goodwill |  |  | 469,025 |  |  |  | 467,789 |
Other intangible assets, net |  |  | 132,849 |  |  |  | 152,756 |
Other assets |  |  | 5,539 |  |  |  | 8,635 |
Total assets |  | $ | 985,682 |  |  | $ | 990,353 |
Liabilities, Convertible and Redeemable Series A-2 Preferred Stock and Stockholders’ Equity |  |  |  |  |  |
Current liabilities |  |  |  |  |  |
Accounts payable and other accrued liabilities |  | $ | 64,514 |  |  | $ | 63,704 |
Accrued payroll and benefits |  |  | 46,299 |  |  |  | 34,248 |
Business acquisitions contingent consideration, current |  |  | 15,609 |  |  |  | 26,872 |
Current portion of operating lease liabilities |  |  | 10,574 |  |  |  | 11,345 |
Current portion of finance lease liabilities |  |  | 6,149 |  |  |  | 4,627 |
Current portion of long-term debt |  |  | 11,209 |  |  |  | 17,866 |
Total current liabilities |  |  | 154,354 |  |  |  | 158,662 |
Non-current liabilities |  |  |  |  |  |
Business acquisitions contingent consideration, long-term |  |  | 7,810 |  |  |  | 6,255 |
Other non-current liabilities |  |  | 7,018 |  |  |  | 5,550 |
Deferred tax liabilities, net |  |  | 16,373 |  |  |  | 13,312 |
Conversion option related to Series A-2 Preferred Stock |  |  | — |  |  |  | 20,224 |
Operating lease liability, net of current portion |  |  | 26,712 |  |  |  | 30,880 |
Finance lease liability, net of current portion |  |  | 12,281 |  |  |  | 11,460 |
Long-term debt, net of deferred financing fees |  |  | 302,415 |  |  |  | 204,818 |
Total liabilities |  | $ | 526,963 |  |  | $ | 451,161 |
Commitments and contingencies |  |  |  |  |  |
Convertible and redeemable series A-2 preferred stock $0.0001 par value |  |  |  |  |  |
Authorized, issued and outstanding shares: 0 and 11,667 at September 30, 2025 and December 31, 2024, respectively; aggregate liquidation preference of $0.0 million and $122.2 million September 30, 2025 and December 31, 2024, respectively |  |  | — |  |  |  | 92,928 |
Stockholders’ equity: |  |  |  |  |  |
Common stock, $0.000004 par value; authorized shares: 190,000,000 at September 30, 2025 and December 31, 2024; issued and outstanding shares: 35,318,532 and 34,309,788 at September 30, 2025 and December 31, 2024, respectively |  |  | — |  |  |  | — |
Additional paid-in-capital |  |  | 728,028 |  |  |  | 721,067 |
Accumulated deficit |  |  | (265,295 | ) |  |  | (272,670 | )
Accumulated other comprehensive loss |  |  | (4,014 | ) |  |  | (2,133 | )
Total stockholders’ equity |  |  | 458,719 |  |  |  | 446,264 |
Total liabilities, convertible and redeemable series A-2 preferred stock and stockholders’ equity |  | $ | 985,682 |  |  | $ | 990,353 |

The accompanying notes are an integral part of these unaudited condensed consolidated financial statements.

1

MONTROSE ENVIRONMENTAL GROUP, INC.

UNAUDITED CONDENSED CONSOLIDATE D STATEMENTS OF OPERATIONS AND

COMPREHENSIVE INCOME (LOSS)

(In thousands, except per share data)

|  | Three Months Ended September 30, |  |  | Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 |  |  | 2025 |  |  | 2024 |
Revenues |  | $ | 224,888 |  |  | $ | 178,687 |  |  | $ | 637,265 |  |  | $ | 507,337 |
Cost of revenues (exclusive of depreciation and amortization shown below) |  |  | 136,284 |  |  |  | 105,596 |  |  |  | 377,492 |  |  |  | 306,239 |
Selling, general and administrative expense |  |  | 65,696 |  |  |  | 60,869 |  |  |  | 205,611 |  |  |  | 177,182 |
Fair value changes in business acquisition contingencies |  |  | 13 |  |  |  | 143 |  |  |  | 844 |  |  |  | 385 |
Depreciation and amortization |  |  | 12,958 |  |  |  | 13,240 |  |  |  | 39,015 |  |  |  | 37,408 |
Income (loss) from operations |  |  | 9,937 |  |  |  | (1,161 | ) |  |  | 14,303 |  |  |  | (13,877 | )
Other income (expense), net |  |  | 10,761 |  |  |  | (3,898 | ) |  |  | 19,084 |  |  |  | (4,314 | )
Interest expense, net |  |  | (5,039 | ) |  |  | (4,137 | ) |  |  | (14,872 | ) |  |  | (11,420 | )
Total other income (expense), net |  |  | 5,722 |  |  |  | (8,035 | ) |  |  | 4,212 |  |  |  | (15,734 | )
Income (loss) before expense from income taxes |  |  | 15,659 |  |  |  | (9,196 | ) |  |  | 18,515 |  |  |  | (29,611 | )
Income tax expense |  |  | 7,281 |  |  |  | 1,368 |  |  |  | 11,140 |  |  |  | 4,480 |
Net income (loss) |  | $ | 8,378 |  |  | $ | (10,564 | ) |  | $ | 7,375 |  |  | $ | (34,091 | )
Equity adjustment from foreign currency translation |  |  | (270 | ) |  |  | (70 | ) |  |  | (1,881 | ) |  |  | (70 | )
Comprehensive income (loss) |  |  | 8,108 |  |  |  | (10,634 | ) |  |  | 5,494 |  |  |  | (34,161 | )
Weighted average common shares outstanding |  |  |  |  |  |  |  |  |  |  |  |
Basic |  |  | 35,300 |  |  |  | 34,242 |  |  |  | 35,003 |  |  |  | 32,647 |
Diluted |  |  | 39,935 |  |  |  | 34,242 |  |  |  | 39,547 |  |  |  | 32,647 |
Net income (loss) per share attributable to common stockholders |  |  |  |  |  |  |  |  |  |  |  |
Basic |  | $ | 0.24 |  |  | $ | (0.39 | ) |  | $ | 0.09 |  |  | $ | (1.30 | )
Diluted |  | $ | 0.21 |  |  | $ | (0.39 | ) |  | $ | 0.08 |  |  | $ | (1.30 | )
Net income (loss) attributable to common stockholders |  |  |  |  |  |  |  |  |  |  |  |
Net income (loss) |  | $ | 8,378 |  |  | $ | (10,564 | ) |  | $ | 7,375 |  |  | $ | (34,091 | )
Convertible and redeemable series A-2 preferred stock dividend |  |  | — |  |  |  | (2,750 | ) |  |  | (4,150 | ) |  |  | (8,314 | )
Net income (loss) attributable to common stockholders |  | $ | 8,378 |  |  | $ | (13,314 | ) |  | $ | 3,225 |  |  | $ | (42,405 | )

The accompanying notes are an integral part of these unaudited condensed consolidated financial statements.

2

MONTROSE ENVIRONMENTAL GROUP, INC.

UNAUDITED COND ENSED CONSOLIDATED STATEMENTS OF CONVERTIBLE AND REDEEMABLE SERIES A-2 PREFERRED STOCK AND STOCKHOLDERS’ EQUITY

(In thousands, except share data)

|  |  |  |  |  |  |  |  |  |  |  |  |  | Accumulated |  |  |
|  | Convertible and Redeemable |  |  |  |  |  | Additional |  |  |  | Other |  | Total |
|  | Series A-2 Preferred Stock |  | Common Stock |  | Paid-In |  | Accumulated |  | Comprehensive |  | Stockholders' |
|  | Shares |  | Amount |  | Shares |  | Amount |  | Capital |  | Deficit |  | Income (Loss) |  | Equity |
Balance at December 31, 2023 |  |  | 17,500 |  | $ | 152,928 |  |  | 30,190,231 |  | $ | — |  | $ | 531,831 |  | $ | (210,356 | ) | $ | (223 | ) | $ | 321,252 |
Net loss |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | (13,357 | ) |  | — |  |  | (13,357 | )
Stock-based compensation |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 11,272 |  |  | — |  |  | — |  |  | 11,272 |
Redemption of Series A-2 preferred stock |  |  | (5,833 | ) |  | (60,000 | ) |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | - |
Dividend payment to the Series A-2 preferred stockholders |  |  | — |  |  | — |  |  | — |  |  | — |  |  | (2,814 | ) |  | — |  |  | — |  |  | (2,814 | )
Common stock issuances pursuant to exercises and vesting of equity awards |  |  | — |  |  | — |  |  | 171,647 |  |  | — |  |  | 487 |  |  | — |  |  | — |  |  | 487 |
Acquisitions consideration paid in common stock |  |  | — |  |  | — |  |  | 220,734 |  |  | — |  |  | 6,580 |  |  | — |  |  | — |  |  | 6,580 |
Acquisitions contingent consideration paid in common stock |  |  | — |  |  | — |  |  | 35,250 |  |  | — |  |  | 1,087 |  |  | — |  |  | — |  |  | 1,087 |
Accumulated other comprehensive loss |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | (35 | ) |  | (35 | )
Balance at March 31, 2024 |  |  | 11,667 |  | $ | 92,928 |  |  | 30,617,862 |  | $ | — |  | $ | 548,443 |  | $ | (223,713 | ) | $ | (258 | ) | $ | 324,472 |
Net loss |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | (10,170 | ) |  | — |  |  | (10,170 | )
Stock-based compensation |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 11,831 |  |  | — |  |  | — |  |  | 11,831 |
Dividend payment to the Series A-2 preferred stockholders |  |  | — |  |  | — |  |  | — |  |  | — |  |  | (2,750 | ) |  | — |  |  | — |  |  | (2,750 | )
Common stock issuances pursuant to exercises and vesting of equity awards |  |  | — |  |  | — |  |  | 39,144 |  |  | — |  |  | 888 |  |  | — |  |  | — |  |  | 888 |
Issuance of common stock pursuant to follow-on offering |  |  | — |  |  | — |  |  | 3,450,000 |  |  | — |  |  | 121,776 |  |  | — |  |  | — |  |  | 121,776 |
Acquisitions contingent consideration paid in common stock |  |  | — |  |  | — |  |  | 61,707 |  |  | — |  |  | 2,691 |  |  | — |  |  | — |  |  | 2,691 |
Accumulated other comprehensive income |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 35 |  |  | 35 |
Balance at June 30, 2024 |  |  | 11,667 |  | $ | 92,928 |  |  | 34,168,713 |  | $ | — |  | $ | 682,879 |  | $ | (233,883 | ) | $ | (223 | ) | $ | 448,773 |
Net loss |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | (10,564 | ) |  | — |  |  | (10,564 | )
Stock-based compensation |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 11,763 |  |  | — |  |  | — |  |  | 11,763 |
Dividend payment to the Series A-2 preferred stockholders |  |  | — |  |  | — |  |  | — |  |  | — |  |  | (2,750 | ) |  | — |  |  | — |  |  | (2,750 | )
Common stock issuances pursuant to exercises and vesting of equity awards |  |  | — |  |  | — |  |  | 96,827 |  |  | — |  |  | 598 |  |  | — |  |  | — |  |  | 598 |
Acquisitions contingent consideration paid in common stock |  |  | — |  |  | — |  |  | 30,953 |  |  | — |  |  | 1,441 |  |  | — |  |  | — |  |  | 1,441 |
Accumulated other comprehensive loss |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | (70 | ) |  | (70 | )
Balance at September 30, 2024 |  |  | 11,667 |  | $ | 92,928 |  |  | 34,296,493 |  | $ | — |  | $ | 693,931 |  | $ | (244,447 | ) | $ | (293 | ) | $ | 449,191 |

The accompanying notes are an integral part of these unaudited condensed consolidated financial statements.

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|  |  |  |  |  |  |  |  |  |  |  |  |  | Accumulated |  |  |
|  | Convertible and Redeemable |  |  |  |  |  | Additional |  |  |  | Other |  | Total |
|  | Series A-2 Preferred Stock |  | Common Stock |  | Paid-In |  | Accumulated |  | Comprehensive |  | Stockholders' |
|  | Shares |  | Amount |  | Shares |  | Amount |  | Capital |  | Deficit |  | Income (Loss) |  | Equity |
Balance at December 31, 2024 |  |  | 11,667 |  | $ | 92,928 |  |  | 34,309,778 |  | $ | — |  | $ | 721,067 |  | $ | (272,670 | ) | $ | (2,133 | ) | $ | 446,264 |
Net loss |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | (19,359 | ) |  | — |  |  | (19,359 | )
Stock-based compensation |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 13,723 |  |  | — |  |  | — |  |  | 13,723 |
Dividend payment to the Series A-2 preferred stockholders |  |  | — |  |  | — |  |  | — |  |  | — |  |  | (2,750 | ) |  | — |  |  | — |  |  | (2,750 | )
Common stock issuances pursuant to exercises and vesting of equity awards |  |  | — |  |  | — |  |  | 473,974 |  |  | — |  |  | 61 |  |  | — |  |  | — |  |  | 61 |
Acquisitions contingent consideration paid in common stock |  |  | — |  |  | — |  |  | 323,834 |  |  | — |  |  | 6,558 |  |  | — |  |  | — |  |  | 6,558 |
Accumulated other comprehensive loss |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | (353 | ) |  | (353 | )
Balance at March 31, 2025 |  |  | 11,667 |  | $ | 92,928 |  |  | 35,107,586 |  | $ | — |  | $ | 738,659 |  | $ | (292,029 | ) | $ | (2,486 | ) | $ | 444,144 |
Net income |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 18,356 |  |  | — |  |  | 18,356 |
Stock-based compensation |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 10,834 |  |  | — |  |  | — |  |  | 10,834 |
Redemption of Series A-2 preferred stock |  |  | (5,833 | ) |  | (60,000 | ) |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Adjustment of preferred stock issuance costs |  |  | — |  |  | 864 |  |  | — |  |  | — |  |  | (864 | ) |  | — |  |  | — |  |  | (864 | )
Dividend payment to the Series A-2 preferred stockholders |  |  | — |  |  | — |  |  | — |  |  | — |  |  | (1,400 | ) |  | — |  |  | — |  |  | (1,400 | )
Common stock issuances pursuant to exercises and vesting of equity awards |  |  | — |  |  | — |  |  | 132,586 |  |  | — |  |  | 16 |  |  | — |  |  | — |  |  | 16 |
Acquisitions contingent consideration paid in common stock |  |  | — |  |  | — |  |  | 32,064 |  |  | — |  |  | 440 |  |  | — |  |  | — |  |  | 440 |
Accumulated other comprehensive loss |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | (1,258 | ) |  | (1,258 | )
Balance at June 30, 2025 |  |  | 5,834 |  | $ | 33,792 |  |  | 35,272,236 |  | $ | — |  | $ | 747,685 |  | $ | (273,673 | ) | $ | (3,744 | ) | $ | 470,268 |
Net income |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 8,378 |  |  | — |  |  | 8,378 |
Stock-based compensation |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 9,220 |  |  | — |  |  | — |  |  | 9,220 |
Redemption of Series A-2 preferred stock |  |  | (5,834 | ) |  | (34,264 | ) |  | — |  |  | — |  |  | (27,971 | ) |  | — |  |  | — |  |  | (27,971 | )
Adjustment of preferred stock issuance costs |  |  | — |  |  | 472 |  |  | — |  |  | — |  |  | (472 | ) |  | — |  |  | — |  |  | (472 | )
Redemption of Series A-2 preferred stock excise tax |  |  | — |  |  | — |  |  | — |  |  | — |  |  | (762 | ) |  | — |  |  | — |  |  | (762 | )
Common stock issuances pursuant to exercises and vesting of equity awards |  |  | — |  |  | — |  |  | 46,296 |  |  | — |  |  | 328 |  |  | — |  |  | — |  |  | 328 |
Accumulated other comprehensive loss |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | (270 | ) |  | (270 | )
Balance at September 30, 2025 |  |  | — |  | $ | — |  |  | 35,318,532 |  | $ | — |  | $ | 728,028 |  | $ | (265,295 | ) | $ | (4,014 | ) | $ | 458,719 |

The accompanying notes are an integral part of these unaudited condensed consolidated financial statements.

4

MONTROSE ENVIRONMENTAL GROUP, INC.

UNAUD ITED CONDENSED CONSOLIDA TED STATEMENTS OF CASH FLOWS

(In thousands)

|  | For the Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 |
Operating activities: |  |  |  |  |  |
Net income (loss) |  | $ | 7,375 |  |  | $ | (34,091 | )
Adjustments to reconcile net income (loss) to net cash provided by operating activities: |  |  |  |  |  |
Provision (recovery) for credit loss |  |  | 7,038 |  |  |  | (367 | )
Depreciation and amortization |  |  | 39,015 |  |  |  | 37,408 |
Non-cash leases expense |  |  | 8,894 |  |  |  | 8,423 |
Stock-based compensation expense |  |  | 33,777 |  |  |  | 34,866 |
Fair value changes in financial instruments |  |  | (18,394 | ) |  |  | 4,851 |
Write off of deferred financing costs |  |  | 913 |  |  |  | — |
Deferred income taxes |  |  | (2,266 | ) |  |  | 4,931 |
Other operating activities, net |  |  | 948 |  |  |  | 682 |
Changes in operating assets and liabilities, net of acquisitions: |  |  |  |  |  |
Accounts receivable and contract assets |  |  | (28,755 | ) |  |  | (45,898 | )
Prepaid expenses and other current assets |  |  | (2,823 | ) |  |  | (3,197 | )
Accounts payable and other accrued liabilities |  |  | 6,094 |  |  |  | (2,192 | )
Accrued payroll and benefits |  |  | 12,051 |  |  |  | (4,936 | )
Change in operating leases |  |  | (8,871 | ) |  |  | (9,233 | )
Other assets |  |  | 552 |  |  |  | (968 | )
Net cash provided by (used in) operating activities |  | $ | 55,548 |  |  | $ | (9,721 | )
Investing activities: |  |  |  |  |  |
Proceeds from corporate owned and property insurance |  |  | — |  |  |  | 182 |
Purchases of property and equipment |  |  | (10,934 | ) |  |  | (19,086 | )
Proceeds from the sale of property and equipment |  |  | 89 |  |  |  | 401 |
Proprietary software development and other software costs |  |  | (1,759 | ) |  |  | (2,052 | )
Purchase price true ups |  |  | — |  |  |  | (3,413 | )
Minority investments |  |  | — |  |  |  | (210 | )
Cash paid for acquisitions, net of cash acquired |  |  | — |  |  |  | (113,012 | )
Net cash used in investing activities |  | $ | (12,604 | ) |  | $ | (137,190 | )
Financing activities: |  |  |  |  |  |
Proceeds from revolving line of credit |  |  | 386,397 |  |  |  | 326,468 |
Repayment of the revolving line of credit |  |  | (305,518 | ) |  |  | (278,335 | )
Repayment of aircraft loan |  |  | (853 | ) |  |  | (796 | )
Proceeds from term loan |  |  | 200,000 |  |  |  | 50,000 |
Repayment of term loan |  |  | (189,218 | ) |  |  | (11,094 | )
Payment of contingent consideration and other purchase price true ups |  |  | (5,458 | ) |  |  | (363 | )
Repayment of finance leases |  |  | (8,923 | ) |  |  | (4,384 | )
Payments of deferred financing costs |  |  | (2,189 | ) |  |  | (348 | )
Proceeds from issuance of common stock for exercised stock options |  |  | 405 |  |  |  | 1,973 |
Proceeds from issuance of common stock in follow-on offering, net of issuance costs |  |  | — |  |  |  | 121,776 |
Proceeds from building sale leaseback |  |  | 2,500 |  |  |  | — |
Dividend payment to the series A-2 stockholders |  |  | (4,150 | ) |  |  | (8,314 | )
Redemption of series A-2 preferred stock |  |  | (122,235 | ) |  |  | (60,000 | )
Net cash provided by (used in) financing activities |  | $ | (49,242 | ) |  | $ | 136,583 |
Change in cash, cash equivalents and restricted cash |  |  | (6,298 | ) |  |  | (10,328 | )
Foreign exchange impact on cash balance |  |  | 99 |  |  |  | 133 |
Cash, cash equivalents and restricted cash: |  |  |  |  |  |
Beginning of year |  |  | 12,935 |  |  |  | 23,240 |
End of period |  | $ | 6,736 |  |  | $ | 13,045 |

The accompanying notes are an integral part of these unaudited condensed consolidated financial statements.

5

|  | For the Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 |
Supplemental disclosures of cash flows information: |  |  |  |  |  |
Cash paid for interest |  | $ | 13,240 |  |  | $ | 10,699 |
Cash paid for income tax |  | $ | 5,379 |  |  | $ | 2,713 |
Supplemental disclosures of non-cash investing and financing activities: |  |  |  |  |  |
Accrued purchases of property and equipment |  | $ | 777 |  |  | $ | 1,810 |
Property and equipment purchased under finance leases |  | $ | 8,020 |  |  | $ | 5,806 |
Common stock issued to acquire new businesses |  | $ | — |  |  | $ | 10,712 |
Acquisitions unpaid contingent consideration |  | $ | 23,419 |  |  | $ | 34,348 |
Acquisitions contingent consideration paid in common stock |  | $ | 6,998 |  |  | $ | 1,087 |

The accompanying notes are an integral part of these unaudited condensed consolidated financial statements.

6

MONTROSE ENVIRONMENTAL GROUP, INC.

NOTES TO UNAUDITED CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(In thousands, except where otherwise indicated)

1. DESCRIPTION OF THE BUSINESS AND BASIS OF PRESENTATION

Description of the Business

Montrose Environmental Group, Inc. (“Montrose” or the “Company”) is a corporation formed on November 2013, under the laws of the State of Delaware. The Company has approximately 120 offices across the United States, Canada, Australia and Europe and approximately 3,500 employees as of September 30, 2025.

Montrose is an environmental services company serving the recurring environmental needs of a diverse client base, including Fortune 500 companies and federal, state and local governments through the following three segments:

Assessment, Permitting and Response segment provides scientific advisory and consulting services to support environmental assessments, environmental emergency response and recovery, toxicology consulting and environmental audits and permits for current operations, facility upgrades, new projects, decommissioning projects and development projects. The Company works closely with clients to navigate the regulatory process at the local, state, provincial and federal levels, to identify the potential environmental and political impacts of their decisions and develop practical mitigation approaches, as needed. In addition to environmental toxicology and given the Company's expertise in helping businesses plan for and respond to disruptions, the Company's scientists and response teams have helped clients navigate their preparation for and response to emergency response situations.

Measurement and Analysis segment is one of the largest providers of environmental testing and laboratory services in North America. The Company's highly credentialed teams test and analyze air, water and soil to determine concentrations of contaminants, as well as the toxicological impact of contaminants on flora, fauna and human health. The Company's offerings include source and ambient air testing and monitoring, leak detection, and advanced multi-media laboratory services, including air, soil, stormwater, wastewater and drinking water analysis.

Remediation and Reuse segment provides clients with engineering, design, and implementation services, primarily to treat contaminated water, remove contaminants from soil or create renewable energy from waste. The Company's team, including engineers, scientists and consultants, provides these services to assist clients in designing solutions, managing products and mitigating environmental risks and liabilities at their locations. The Company does not own the properties or facilities at which it implements these projects or the underlying liabilities, nor does the Company own material amounts of the equipment used in projects.

Basis of Presentation

The unaudited condensed consolidated financial statements include the operations of the Company and its wholly-owned subsidiaries. These unaudited condensed consolidated financial statements are presented in conformity with accounting principles generally accepted in the United States (U.S. GAAP) and have been prepared pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (SEC) that permit reduced disclosure for interim periods. The unaudited condensed consolidated financial statements include all accounts of the Company and, in the opinion of management, include all recurring adjustments and normal accruals necessary for a fair statement of the Company’s financial position, results of operations and cash flows for the dates and periods presented. These unaudited condensed consolidated financial statements should be read in conjunction with the Company’s audited financial statements as of and for the year ended December 31, 2024. Results for interim periods are not necessarily indicative of the results to be expected during the remainder of the current year or for any future period. All intercompany transactions, accounts and profits, have been eliminated in the unaudited condensed consolidated financial statements.

Within the unaudited condensed consolidated statements of cash flows certain amounts in the prior period have been reclassified to conform with current period presentation. The prior period amount for provision (recovery) for credit loss was previously included within other operating activities, net. The prior period amount for changes in operating assets and liabilities, net of acquisitions: prepaid expenses and other current assets was previously included within changes in operating assets and liabilities, net of acquisitions: other assets. These changes had no effect on the Company's results of operations or financial position, and no material impact on the Company's cash flow.

2. SUMMARY OF NEW ACCOUNTING PRONOUNCEMENTS

Recently Adopted Accounting Pronouncements

ASU 2023-05 —In August 2023, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2023-05 Business Combinations — Joint Venture Formations (Subtopic 805-60): Recognition and Initial Measurement, under which an entity that qualifies

7

as either a joint venture or a corporate joint venture is required to apply a new basis of accounting upon the formation of the joint venture. Specifically, the ASU provides that a joint venture or a corporate joint venture must initially measure its assets and liabilities at fair value on the formation date. The amendments in ASU 2023-05 are effective for all joint ventures within the ASU’s scope that are formed on or after January 1, 2025. The Company adopted the standard on January 1, 2025. The adoption of the standard did not have a material impact on the Company's consolidated financial statements.

Recently Issued Accounting Pronouncements Not Yet Adopted

ASU 2023-09 —In December 2023, the FASB issued ASU 2023-09, Improvements to Income Tax Disclosures, which improves the transparency of income tax disclosures by requiring consistent categories and greater disaggregation of information in the rate reconciliation and income taxes paid disaggregated by jurisdiction. It also includes certain other amendments to improve the effectiveness of income tax disclosures. ASU 2023-09 is effective for the Company's fiscal year beginning after December 15, 2024 and allows the use of a prospective or retrospective approach. The Company does not expect the adoption of the standard will have a material impact on its consolidated financial statements.

ASU 2024-03 —In November 2024, the FASB issued ASU 2024-03, Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses (ASU 2024-03), which is intended to improve the disclosures about a public business entity’s expenses and address requests from investors for more detailed information about the types of expenses in commonly presented expense captions (such as cost of sales; selling, general, and administrative expenses; and research and development). ASU 2024-03 is effective for the Company's fiscal year beginning January 1, 2027 and interim periods within fiscal years beginning after December 15, 2027, and allows the use of a prospective or retrospective approach. The Company plans to adopt the standard on January 1, 2027 and is currently evaluating the impact of the adoption of the standard on its consolidated financial statements.

ASU 2025-06 —In September 2025, the FASB issued ASU 2025-06, Intangibles — Goodwill and Other — Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software (ASU 2025-06), which removes all references to software development project stages, making the guidance neutral to different software development methodologies. Under the ASU, software capitalization will begin when management has authorized and committed to funding the software project and it is probable that the project will be completed and the software will be used as intended. ASU 2025-06 is effective for the Company's fiscal year beginning January 1, 2028, and interim periods within fiscal years beginning after December 15, 2027, and allows the use of a prospective, modified transition, or retrospective approach. Early adoption is permitted. The Company is currently evaluating the impact of the adoption of the standard on its consolidated financial statements.

3. REVENUES AND ACCOUNTS RECEIVABLE

The Company’s main revenue sources derive from the following revenue streams:

Assessment, Permitting and Response Revenues are generated from multidisciplinary environmental consulting services. The majority of the contracts are fixed-fee or time-and-material based.

Measurement and Analysis Revenues are generated from emissions sampling, testing and reporting services, leak detection services, ambient air monitoring services and laboratory testing services. The majority of the contracts are fixed-fee or time-and-materials based.

Remediation and Reuse Revenues are generated from engineering, design, implementation and operating and maintenance (O&M) services primarily to treat contaminated water, remove contaminants from soil or create renewable energy from waste. The majority of the contracts are fixed-fee and time-and-materials based. Services on the majority of O&M contracts are provided under long-term fixed-fee contracts.

Disaggregation of Revenue—The Company disaggregates revenue by its operating segments and geographic location. The Company believes disaggregating revenue into these categories achieves the disclosure objectives to depict how the nature, amount, and uncertainty of revenue and cash flows are affected by economic factors. Disaggregated revenue disclosures are provided in Note 19.

Contract Balances—The Company presents contract balances for unbilled receivables (contract assets), as well as customer advances, deposits and deferred revenue (contract liabilities) within contract assets and accounts payable and other accrued expenses, respectively, on the unaudited condensed consolidated statements of financial position. Amounts are generally billed at periodic intervals (e.g. weekly, bi-weekly or monthly) as work progresses in accordance with agreed-upon contractual terms. The Company utilizes the practical expedient to not adjust the promised amount of consideration for the effects of a significant financing component for arrangements in which the period between when the Company transfers services to a customer and when the customer pays for those services is one year or less. Amounts recorded as unbilled receivables are generally for services the Company is not entitled to bill based on the passage of time. Under certain contracts, billing occurs subsequent to revenue recognition, resulting in contract assets. The Company sometimes receives advances or deposits from customers before revenue is recognized, resulting in contract liabilities.

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The following table presents the Company’s contract balances:

|  | September 30, |  |  | December 31, |
|  | 2025 |  |  | 2024 |
Contract assets |  | $ | 68,743 |  |  | $ | 52,091 |
Contract liabilities |  |  | 13,827 |  |  |  | 9,297 |

Contract assets acquired through business acquisitions amounted to $0.0 million and $2.6 m illion as of September 30, 2025 and December 31, 2024, respectively.

Revenue recognized during the three and nine months ended September 30, 2025, included in the contract liabilities balance at the beginning of the year was $0.9 million and $5.0 million, respectively. The revenue recognized from the contract liabilities consisted of the Company satisfying performance obligations during the normal course of business.

Remaining Unsatisfied Performance Obligations—Remaining unsatisfied performance obligations represent the total dollar value of work to be performed on contracts awarded and in progress. The amount of remaining unsatisfied performance obligations increases with new contracts or additions to existing contracts and decreases as revenue is recognized on existing contracts. Contracts are included in the amount of remaining unsatisfied performance obligations when an enforceable agreement has been reached. As of September 30, 2025 and December 31, 2024, the estimated revenue expected to be recognized in the future related to performance obligations that are unsatisfied was approximately $71.4 million and $77.3 million, respectively. As of September 30, 2025, the Company expected to recognize approximately $52.0 million of this amount as revenue within one year and $19.4 million the year after.

Accounts Receivable, Net—Th e Company extends non-interest-bearing trade credit to its customers in the ordinary course of business. Accounts receivable, net consisted of the following:

|  | September 30, 2025 |  |  | December 31, 2024 |
Accounts receivable, invoiced |  | $ | 173,457 |  |  | $ | 160,976 |
Allowance for doubtful accounts |  |  | (8,143 | ) |  |  | (2,093 | )
Accounts receivable, net |  | $ | 165,314 |  |  | $ | 158,883 |

The Company ha d one cu stomer that exceeded 10.0% of its gross receivables as of September 30, 2025 and none as of December 31, 2024. For the three and nine months ended September 30, 2025, the Company had one cu stomer who accounted for more than 10.0% of revenue. For the three and nine months ended September 30, 2024 the Company had no customers who accounted for more than 10% of revenue. The Company performs ongoing credit evaluations and based on past collection experience, the Company believes that the receivable balance from its largest customer does not represent a significant credit risk.

From time to time, we may sell certain accounts receivable to a financial institution on a non-recourse basis for cash, less a discount at a rate that approximates the interest rate on our senior secured credit facility. We have no retained interests in the sold receivables and only perform collection and administrative functions for the purchaser. We account for these receivable transfers as sales under ASC 860, Transfers and Servicing. Receivables sold during the three and nine months ended September 30, 2025 was $0.0 million and $13.4 million, respectively. Proceeds from the sale of receivables approximated their book value and are included in operating cash flows on the Consolidated Statements of Cash Flows. All receivables sold during the nine months ended September 30, 2025 have been fully collected as of September 30, 2025.

The allowance for doubtful accounts consisted of the following:

|  | Beginning Balance |  |  | Bad Debt Expense (Recovery) |  |  | Charged to Allowance |  |  | Ending Balance |
Nine months ended September 30, 2025 |  | $ | 2,093 |  |  | $ | 7,038 |  |  | $ | (988 | ) |  | $ | 8,143 |
Year ended December 31, 2024 |  |  | 2,724 |  |  |  | (146 | ) |  |  | (485 | ) |  |  | 2,093 |

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4. PREPAID AND OTHER CURRENT ASSETS

Prepaid and other current assets consisted of the following:

|  | September 30, 2025 |  |  | December 31, 2024 |
Deposits |  | $ | 1,101 |  |  | $ | 1,073 |
Prepaid expenses |  |  | 10,619 |  |  |  | 10,223 |
Supplies |  |  | 3,465 |  |  |  | 2,794 |
Prepaid and other current assets |  | $ | 15,185 |  |  | $ | 14,090 |

5. PROPERTY AND EQUIPMENT, NET

Property and equipment, net, consisted of the following:

|  | September 30, 2025 |  |  | December 31, 2024 |
Lab and test equipment |  | $ | 24,919 |  |  | $ | 24,421 |
Vehicles |  |  | 6,625 |  |  |  | 6,360 |
Equipment |  |  | 69,031 |  |  |  | 60,763 |
Furniture and fixtures |  |  | 3,281 |  |  |  | 3,221 |
Leasehold improvements |  |  | 14,224 |  |  |  | 14,029 |
Aircraft |  |  | 12,386 |  |  |  | 12,386 |
Building |  |  | 5,748 |  |  |  | 5,763 |
|  |  | 136,214 |  |  |  | 126,943 |
Land |  |  | 1,089 |  |  |  | 1,089 |
Construction in progress |  |  | 3,079 |  |  |  | 3,993 |
Less: Accumulated depreciation |  |  | (77,430 | ) |  |  | (68,249 | )
Total property and equipment—net |  | $ | 62,952 |  |  | $ | 63,776 |

Total depreciation expense included in the unaudited condensed consolidated statements of operations was $3.3 million and $9.7 million for the three and nine months ended September 30, 2025, respectively, and $2.8 million and $8.7 million for the three and nine months ended September 30, 2024, respectively.

6. LEASES

Leases are classified as either finance leases or operating leases based on criteria in Accounting Standard Codification (ASC) 842. The Company has finance leases for its vehicle and equipment leases and operating leases for its real estate space and office equipment leases. The Company’s operating and finance leases generally have original lease terms between 1 year and 15 years, and in some instances include one or more options to renew. The Company includes options to extend the lease term in the initial measurement of leases if the options are reasonably certain of being exercised. The Company currently considers some of its renewal options to be reasonably certain to be exercised. Some leases also include early termination options, which can be exercised under specific conditions. The Company does not have material residual value guarantees or restrictive covenants associated with its leases.

Finance and operating lease right-of-use (ROU) assets represent the right to use an underlying asset for the lease term, and finance and operating lease liabilities represent the obligation to make lease payments arising from the lease.

The Company calculates the present value of its finance and operating leases using an estimated incremental borrowing rate (IBR), which requires judgment. For real estate operating leases, the Company estimates the IBR based on prevailing market rates for collateralized debt in a similar economic environment with similar payment terms and maturity dates commensurate with the terms of the lease. For all other leases, the Company estimates the IBR based on the stated interest rate on the contract. Since many of the inputs used to calculate the rate implicit in the leases are not readily determinable from the lessee’s perspective, the Company does not use the implicit interest rate.

Certain leases contain variable payments, these payments are expensed as incurred and not included in the Company’s operating lease ROU assets and operating lease liabilities. These amounts primarily include payments for maintenance, utilities, taxes, and insurance and are excluded from the present value of the Company’s lease obligations.

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The Company does not record operating lease ROU assets or operating lease liabilities for leases with an initial term of 12 months or less. The Company also combines lease and non-lease components on all new or modified operating leases into a single lease component for all classes of assets.

When a lease is terminated before the expiration of the lease term, irrespective of whether the lease is classified as a finance lease or an operating lease, the lessee would derecognize the ROU asset and corresponding lease liability. Any difference would be recognized as a gain or loss related to the termination of the lease. Similarly, if a lessee is required to make any payments or receives any consideration when terminating the lease, it would include such amounts in the determination of the gain or loss upon termination.

Equipment Line of Credit—In May 2024, the Company entered into a $15.0 million equipment leasing facility for the purchase of equipment and related freight, installation costs and taxes paid. Any unused capacity on this equipment leasing facility will expire on February 25, 2026. Interest on leases financed under this facility is based on the SOFR swap rate on or closest to the closing date. Equipment leased through this line of credit met the finance lease criteria as per ASC 842 and accordingly is accounted for as finance lease right-of-use assets and finance lease liabilities.

The components of lease expense were as follows:

|  |  | For the Three Months Ended September 30, |
| Statement of Operations Location |  | 2025 |  |  | 2024 |
Operating lease cost |  |  |  |  |  |  |
Lease cost | Selling, general and administrative expense |  | $ | 3,064 |  |  | $ | 3,319 |
Variable lease cost | Selling, general and administrative expense |  |  | 695 |  |  |  | 651 |
Total operating lease cost |  |  | $ | 3,759 |  |  | $ | 3,970 |
Finance lease cost |  |  |  |  |  |  |
Amortization of ROU assets | Depreciation and amortization |  | $ | 2,394 |  |  | $ | 1,496 |
Interest on lease liabilities | Interest expense, net |  |  | 348 |  |  |  | 26 |
Total finance lease cost |  |  | $ | 2,742 |  |  | $ | 1,522 |
Total lease cost |  |  | $ | 6,501 |  |  | $ | 5,492 |
|  |  | For the Nine Months Ended September 30, |
| Statement of Operations Location |  | 2025 |  |  | 2024 |
Operating lease cost |  |  |  |  |  |  |
Lease cost | Selling, general and administrative expense |  | $ | 9,299 |  |  | $ | 10,421 |
Variable lease cost | Selling, general and administrative expense |  |  | 2,285 |  |  |  | 1,687 |
Total operating lease cost |  |  | $ | 11,584 |  |  | $ | 12,108 |
Finance lease cost |  |  |  |  |  |  |
Amortization of ROU assets | Depreciation and amortization |  | $ | 6,353 |  |  | $ | 4,068 |
Interest on lease liabilities | Interest expense, net |  |  | 925 |  |  |  | 425 |
Total finance lease cost |  |  | $ | 7,278 |  |  | $ | 4,493 |
Total lease cost |  |  | $ | 18,862 |  |  | $ | 16,601 |

Supplemental cash flows information related to leases was as follows:

|  | For the Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 |
Cash paid for amounts included in the measurement of lease liabilities: |  |  |  |  |  |
Operating cash flows used in operating leases |  | $ | 10,357 |  |  | $ | 9,748 |
Operating cash flows used for interest related to finance leases |  |  | 878 |  |  |  | 425 |
Financing cash flows used in finance leases |  |  | 4,697 |  |  |  | 4,384 |
Lease liabilities arising from new ROU assets: |  |  |  |  |  |
Operating leases |  |  | 4,726 |  |  |  | 14,676 |
Finance leases |  |  | 7,143 |  |  |  | 5,806 |

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Weighted average remaining lease terms and weighted average discount rates were:

|  | September 30, 2025 |
|  | Operating Leases |  |  | Finance Leases |
Weighted average remaining lease term (years) |  |  | 4.2 |  |  |  | 3.3 |
Weighted average discount rate |  |  | 5.0 | % |  |  | 6.7 | %
|  | September 30, 2024 |
|  | Operating Leases |  |  | Finance Leases |
Weighted average remaining lease term (years) |  |  | 4.4 |  |  |  | 3.5 |
Weighted average discount rate |  |  | 4.6 | % |  |  | 6.6 | %

The following is a schedule by year of the maturities of lease liabilities with original terms in excess of one year:

|  | Operating Leases |  |  | Finance Leases |
Remainder of 2025 |  | $ | 3,266 |  |  | $ | 1,913 |
2026 |  |  | 11,591 |  |  |  | 6,827 |
2027 |  |  | 8,972 |  |  |  | 5,439 |
2028 |  |  | 7,311 |  |  |  | 3,752 |
2029 |  |  | 5,485 |  |  |  | 2,319 |
2030 and thereafter |  |  | 4,942 |  |  |  | 256 |
Total undiscounted future minimum lease payments |  | $ | 41,567 |  |  | $ | 20,506 |
Less imputed interest |  |  | (4,281 | ) |  |  | (2,076 | )
Total discounted future minimum lease payments |  | $ | 37,286 |  |  | $ | 18,430 |

7. BUSINESS ACQUISITIONS

During the nine months ended September 30, 2025, the Company did not complete any business acquisitions; however, strategic acquisitions remain a core part of the Company's growth strategy.

The Company may be required to make up to $23.4 million in aggregate earn-out payments between the years 2025 and 2027 in connection with certain of its business acquisitions, of which up to $10.4 million may be paid only in cash, up to $2.8 million may be paid only in common stock and up to $10.2 million may be paid, at the Company’s option, in cash or common stock.

Transaction costs related to previous business combinations totaled $0.8 million and $1.8 million for the three and nine months ended September 30, 2025, respectively, and $2.8 million and $6.4 million for the three and nine months ended September 30, 2024, respectively. These costs are expensed within selling, general and administrative expense in the accompanying unaudited condensed consolidated statements of operations.

During the nine months ended September 30, 2025, measurement period adjustments of $1.2 mi llion were recorded (Note 8).

Acquisitions Completed During the Year Ended December 31, 2024

Epic Environmental Pty LTD (Epic)—In January 2024, the Company completed the acquisition of Epic by acquiring 100% of its common stock. Epic is an environmental consultancy, based in Brisbane, Australia, and serving clients across Australia.

Two Dot Consulting, LLC (2DOT)—In February 2024, the Company completed the acquisition of 2DOT by acquiring 100% of its membership interests. 2DOT is a leading environmental consultancy in the Rocky Mountain and adjacent regions, and is based in Denver, Colorado.

Engineering & Technical Associates, Inc. (ETA)—In April 2024, the Company acquired substantially all of the assets of ETA. ETA is a niche consulting firm focusing on providing process safety management, process hazardous analysis, and other safety-focused services to industrial clients throughout the United States.

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Paragon Soil and Environmental Consulting Inc. (Paragon)—In May 2024, the Company completed the acquisition of Paragon by acquiring 100% of its ownership and interest. Paragon is an environmental consulting firm that provides services for clients across western Canada.

Spirit Environmental, LLC. (Spirit)—In July 2024, the Company completed the acquisition of Spirit by acquiring 100% of its membership interests. Spirit is a leading environmental consultant specializing in air permitting and compliance services across the central U.S. Spirit is based in Houston, Texas.

Origins Laboratory, Inc. (Origins)—In September 2024, the Company acquired substantially all of the assets of Origins. Origins is an accredited environmental analytical testing laboratory based in Denver, Colorado.

For the acquisitions completed during the nine months ended September 30, 2024, the results of operations since the acquisition dates have been combined with those of the Company. The Company’s unaudited condensed consolidated statement of operations for the three and nine months ended September 30, 2024 includes revenue of $15.0 million and $26.6 million, respectively, and pre-tax income of $3.0 million and $5.4 million, respectively, related to these acquisitions.

Supplemental Unaudited Pro-Forma—The unaudited consolidated financial information summarized in the following table gives effect to all acquisitions completed in 2024 assuming they occurred on January 1, 2024. These unaudited consolidated pro-forma operating results do not assume any impact from revenue, cost or other operating synergies that are expected or may have been realized as a result of the acquisitions. These unaudited consolidated pro forma operating results include results from certain acquired companies that have not been audited and whose accounting policies prior to acquisition may differ from those of the Company. As a result, these unaudited consolidated pro forma operating results may not be comparable to revenues and earnings had these consolidated pro forma results been audited and consistent accounting policies applied. These unaudited consolidated pro-forma operating results are presented for illustrative purposes only and are not indicative of the operating results that would have been achieved had the acquisitions occurred on January 1, 2024 nor does the information project results for any future period. Please refer to the Company's 2024 Form 10-K for information regarding the 2024 acquisitions.

|  | For the Three Months Ended September 30, |
|  | 2025 |  |  | 2024 |
|  | As reported |  |  | Acquisitions Pro-Forma (Unaudited) |  |  | Consolidated Pro-Forma (Unaudited) |  |  | As reported |  |  | Acquisitions Pro-Forma (Unaudited) |  |  | Consolidated Pro-Forma (Unaudited) |
Revenues |  | $ | 224,888 |  |  | $ | — |  |  | $ | 224,888 |  |  | $ | 178,687 |  |  | $ | 2,623 |  |  | $ | 181,310 |
Net (loss) income |  | $ | 8,378 |  |  | $ | — |  |  | $ | 8,378 |  |  | $ | (10,564 | ) |  | $ | 1,583 |  |  | $ | (8,981 | )
|  | For the Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 |
|  | As reported |  |  | Acquisitions Pro-Forma (Unaudited) |  |  | Consolidated Pro-Forma (Unaudited) |  |  | As reported |  |  | Acquisitions Pro-Forma (Unaudited) |  |  | Consolidated Pro-Forma (Unaudited) |
Revenues |  | $ | 637,265 |  |  | $ | — |  |  | $ | 637,265 |  |  | $ | 507,337 |  |  | $ | 23,225 |  |  | $ | 530,562 |
Net (loss) income |  | $ | 7,375 |  |  | $ | — |  |  | $ | 7,375 |  |  | $ | (34,091 | ) |  | $ | 8,672 |  |  | $ | (25,419 | )

8. GOODWILL AND INTANGIBLE ASSETS

Amounts related to goodwill are as follows:

|  | Assessment, Permitting and Response |  |  | Measurement and Analysis |  |  | Remediation and Reuse |  |  | Total |
Balance as of December 31, 2024 |  | $ | 205,231 |  |  | $ | 118,860 |  |  | $ | 143,698 |  |  | $ | 467,789 |
Acquisitions measurement period adjustments, net of foreign currency translation |  |  | 1,096 |  |  |  | 220 |  |  |  | (80 | ) |  |  | 1,236 |
Balance as of September 30, 2025 |  | $ | 206,327 |  |  | $ | 119,080 |  |  | $ | 143,618 |  |  | $ | 469,025 |

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Amounts related to finite-lived intangible assets are as follows:

September 30, 2025 |  | Gross Balance |  |  | Accumulated Amortization |  |  | Total Intangible Assets—Net |
Customer relationships |  | $ | 264,958 |  |  | $ | 155,589 |  |  | $ | 109,369 |
Covenants not to compete |  |  | 41,529 |  |  |  | 35,787 |  |  |  | 5,742 |
Trade names |  |  | 25,939 |  |  |  | 25,056 |  |  |  | 883 |
Proprietary software |  |  | 31,201 |  |  |  | 25,227 |  |  |  | 5,974 |
Patent |  |  | 17,479 |  |  |  | 6,598 |  |  |  | 10,881 |
Total other intangible assets, net |  | $ | 381,106 |  |  | $ | 248,257 |  |  | $ | 132,849 |
December 31, 2024 |  | Gross Balance |  |  | Accumulated Amortization |  |  | Total Intangible Assets—Net |
Customer relationships |  | $ | 264,477 |  |  | $ | 138,787 |  |  | $ | 125,690 |
Covenants not to compete |  |  | 41,758 |  |  |  | 33,898 |  |  |  | 7,860 |
Trade names |  |  | 25,939 |  |  |  | 23,375 |  |  |  | 2,564 |
Proprietary software |  |  | 28,428 |  |  |  | 23,489 |  |  |  | 4,939 |
Patent |  |  | 17,479 |  |  |  | 5,776 |  |  |  | 11,703 |
Total other intangible assets, net |  | $ | 378,081 |  |  | $ | 225,325 |  |  | $ | 152,756 |

Intangible assets with finite lives are stated at cost, less accumulated amortization and impairment losses, if any. These intangible assets are amortized using the straight-line method over the estimated useful lives of the assets.

Amortization expense was $7.3 million and $23.0 million for the three and nine months ended September 30, 2025, respectively, and $9.0 million and $24.6 million for the three and nine months ended September 30, 2024, respectively.

Future amortization expense is estimated to be as follows for each of the five following years and thereafter:

December 31, |  |  |
2025 (remaining) |  | $ | 6,845 |
2026 |  |  | 25,635 |
2027 |  |  | 24,381 |
2028 |  |  | 18,967 |
2029 |  |  | 12,380 |
Thereafter |  |  | 44,641 |
Total |  | $ | 132,849 |

9. ACCOUNTS PAYABLE AND OTHER ACCRUED LIABILITIES

Accounts payable and other accrued liabilities consisted of the following:

|  | September 30, 2025 |  |  | December 31, 2024 |
Accounts payable |  | $ | 28,528 |  |  | $ | 33,424 |
Accrued expenses |  |  | 12,279 |  |  |  | 16,190 |
Other business acquisitions purchase price obligations |  |  | — |  |  |  | 568 |
Contract liabilities |  |  | 13,827 |  |  |  | 9,297 |
Other current liabilities |  |  | 9,880 |  |  |  | 4,225 |
Total accounts payable and other accrued liabilities |  | $ | 64,514 |  |  | $ | 63,704 |

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10. ACCRUED PAYROLL AND BENEFITS

Accrued payroll and benefits consisted of the following:

|  | September 30, 2025 |  |  | December 31, 2024 |
Accrued bonuses |  | $ | 23,502 |  |  | $ | 14,433 |
Accrued paid time off |  |  | 4,595 |  |  |  | 4,214 |
Accrued payroll |  |  | 12,145 |  |  |  | 11,969 |
Accrued other |  |  | 6,057 |  |  |  | 3,632 |
Total accrued payroll and benefits |  | $ | 46,299 |  |  | $ | 34,248 |

11. INCOME TAXES

The Company calculates its interim income tax provision in accordance with ASC Topic 270, Interim Reporting (ASC 270), and ASC 740, Income Taxes. The Company’s effective tax rate (ETR) from continuing operations was 46.5% and 60.2% for the three and nine months ended September 30, 2025, respectively, and (14.9)% and (15.1)% for the three and nine months ended September 30, 2024, respectively. Income tax expense recorded by the Company during the three and nine months ended September 30, 2025 was $7.3 million and $11.1 million, respectively. Income tax expense recorded by the Company during the three and nine months ended September 30, 2024 was $1.4 million and $4.5 million, respectively. The difference between the ETR and federal statutory rate of 21.0% is primarily attributable to the impact of tax-deductible goodwill, recognition of a U.S. federal and state valuation allowance and state and foreign income tax provisions.

A valuation allowance is recorded when it is more-likely-than-not that some of the Company’s deferred tax assets may not be realized. Significant judgment is applied when assessing the need for a valuation allowance and the Company considers future taxable income, reversals of existing deferred tax assets and liabilities and ongoing prudent and feasible tax planning strategies, in making such assessment. As of September 30, 2025, the Company’s U.S. federal, state and various foreign net deferred tax assets are not more-likely-than-not to be realized and a full valuation allowance is maintained with respect to such jurisdictions.

The Company records uncertain tax positions in accordance with ASC 740, on the basis of a two-step process in which (i) the Company determines whether it is more likely than not a tax position will be sustained on the basis of the technical merits of such position and (ii) for those tax positions meeting the more-likely-than-not recognition threshold, the Company would recognize the largest amount of tax benefit that is more than 50.0% likely to be realized upon ultimate settlement with the related tax authority. The Company has determined it has no material uncertain tax positions as of September 30, 2025. The Company classifies interest and penalties recognized on uncertain tax positions as a component of income tax expense.

The One Big Beautiful Bill Act ("OBBB Act") was enacted on July 4, 2025, in the United States. The OBBB Act includes several significant provisions, including re-establishing a 100% bonus depreciation deduction, re-establishing rules in calculating business interest expense limitations pursuant to Internal Revenue Code §163(j), changing the calculation of international tax inclusions, and removing the capitalization requirements for domestic research or experimental (R&E) expenditures paid or incurred in tax years beginning after December 31, 2024. Management included the current tax impact of such provisions in the computation of current quarter income tax expense. Such provisions did not impact existing deferred tax assets or liabilities, as of December 31, 2024.

12. DEBT

Debt consisted of the following:

|  | September 30, 2025 |  |  | December 31, 2024 |
Term loan facility |  | $ | 200,000 |  |  | $ | 189,218 |
Revolving line of credit |  |  | 107,095 |  |  |  | 25,191 |
Aircraft loan |  |  | 8,419 |  |  |  | 9,272 |
Less deferred debt issuance costs |  |  | (1,890 | ) |  |  | (997 | )
Total debt |  | $ | 313,624 |  |  | $ | 222,684 |
Less current portion of long-term debt |  |  | (11,209 | ) |  |  | (17,866 | )
Long-term debt, less current portion |  | $ | 302,415 |  |  | $ | 204,818 |

Deferred Financing Costs—Costs relating to debt issuance have been deferred and are netted against the underlying debt balance. These costs are amortized to interest expense over the terms of the underlying debt instruments.

15

2021 Credit Facility—On April 27, 2021, the Company entered into a Senior Secured Credit Agreement providing for a $300.0 million credit facility comprised of a $175.0 million term loan and a $125.0 million revolving line of credit (2021 Credit Facility), and used a portion of the proceeds from the 2 021 Credit Facility to repay all amounts outstanding under the prior credit facility. The revolving line of credit portion of the 2021 Credit Facility included a $20.0 million sublimit for the issuance of letters of credit. Subject to certain exceptions, all amounts under the 2021 Credit Facility were to become due on April 27, 2026. The Company had the option to borrow incremental term loans or request an increase in the aggregate commitments under the revolving line of credit up to an aggregate amount of $150.0 million subject to the satisfaction of certain conditions.

In February 2024, the Company partially exercised its option to request an increase in the aggregate commitments to provide an additional $100.0 million credit availability under the 2021 Credit Facility, comprised of an additional $50.0 million term loan (Additional Term Loan) and an additional $50.0 million in availability under the revolving line of credit.

In February 2025, the 2021 Credit Facility was paid in full via proceeds from the 2025 Credit Facility, as described below. The resulting write-off of the remaining unamortized debt issuance costs from the 2021 Credit Facility amounted to $0.9 million. Total loss on debt extinguishments is recorded in interest expense-net within the condensed consolidated statement of operations for the nine months ended September 30, 2025.

2025 Credit Facility—On February 26, 2025, the Company entered into an Amended and Restated Senior Secured Credit Agreement providing for a $500.0 million credit facility comprised of a $200.0 million term loan and a $300.0 million revolving line of credit (2025 Credit Facility), and used a portion of the proceeds from the 2025 Credit Facility to repay all amounts outstanding under the 2021 Credit Facility. The revolving line of credit under the 2025 Credit Facility includes a $20.0 million sublimit for the issuances of letters of credit. Subject to certain exceptions, all amounts under the 2025 Credit Facility will become due on February 26, 2030. The Company has the option to borrow incremental term loans, or request an increase in aggregate commitments under the revolving line of credit up to an aggregate amount of $200.0 million, subject to the satisfaction of certain conditions.

The 2025 Credit Facility term loan must be repaid in quarterly installments and shall amortize at a rate of 1.25% per quarter beginning December 31, 2025 through December 31, 2029, with final payment and amortization on February 26, 2030.

The 2025 Credit Facility term loan and the revolving line of credit bear interest subject to the applicable spread based on the Company’s leverage ratio and SOFR as follows:

Pricing Tier |  | Consolidated Leverage Ratio |  | Senior Credit Facilities SOFR Spread |  |  | Senior Credit Facilities Base Rate Spread |  |  | Commitment Fee |  |  | Letter of Credit Fee |  |
1 |  | ≥ 3.75 x to 1.0 |  |  | 2.50 |  | % |  | 1.50 |  | % |  | 0.25 |  | % |  | 2.50 |  | %
2 |  | < 3.75 x to 1.0 but ≥ 3.25 to 1.0 |  |  | 2.25 |  |  |  | 1.25 |  |  |  | 0.23 |  |  |  | 2.25 |  |
3 |  | <3.25 x to 1.0 but ≥ 2.50 to 1.0 |  |  | 2.00 |  |  |  | 1.00 |  |  |  | 0.20 |  |  |  | 2.00 |  |
4 |  | <2.50 x to 1.0 but ≥ 1.75 to 1.0 |  |  | 1.75 |  |  |  | 0.75 |  |  |  | 0.15 |  |  |  | 1.75 |  |
5 |  | <1.75 x to 1.0 |  |  | 1.50 |  |  |  | 0.50 |  |  | 0.15 |  |  |  | 1.50 |  |

The 2025 Credit Facility includes a number of covenants imposing certain restrictions on the Company’s business, including, among other things, restrictions on the Company’s ability, subject to certain exceptions and baskets, to incur indebtedness, incur liens on its assets, agree to any additional negative pledges, pay dividends or repurchase stock, limit the ability of its subsidiaries to pay dividends or distribute assets, make investments, enter into any transaction of merger or consolidation, liquidate, wind-up or dissolve, or convey any part of its business, assets or property, or acquire the business, property or assets of another person, enter into sale and leaseback transactions, enter into certain transactions with affiliates, engage in any material line of business substantially different from those engaged on the closing date, modify the terms of indebtedness subordinated to the loans incurred under the 2025 Credit Facility and modify the terms of its organizational documents. The 2025 Credit Facility permits certain restricted payments, including common stock repurchases, subject to a maximum pro-forma leverage ratio of 3.00 times, and minimum pro-forma fixed charge coverage ratio of 1.25 times and no event of default. The 2025 Credit Facility also includes financial covenants which require the Company to remain below a maximum total net leverage ratio of 4.00 times until the fiscal quarter ending March 31, 2026, stepping down to 3.75 times thereafter, and a minimum fixed charge coverage ratio of 1.25 times.

The Company deferred $2.2 million of debt issuance costs related to the 2025 Credit Facility in the first quarter of 2025. Quarterly installment repayments for the term loan under the 2025 Credit Facility will commence in the fourth quarter of 2025. For the three and nine months ended September 30, 2024 quarterly term loan installment repayments under the 2021 Credit Facility were $3.9 million and $11.1 million, respectively.

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As of September 30, 2025 and December 31, 2024, the Company’s consolidated total leverage ratio (as defined in the 2025 and 2021 Credit Facility, respectively) was 2.7 time s and 2.1 times, respe ctively, and the Company was in compliance with all covenants under the 2025 and 2021 Credit Facility.

The 2025 Credit Facility requires customary mandatory prepayments of the term loan and revolver and cash collateralization of letters of credit, subject to customary exceptions, including 100.0% of the proceeds of debt not permitted by the 2025 Credit Facility, 100.0% of the proceeds of certain dispositions, subject to customary reinvestment rights, where applicable, and 100.0% of insurance or condemnation proceeds, subject to customary reinvestment rights, where applicable. The 2025 Credit Facility also includes customary events of default and related acceleration and termination rights.

The weighted average interest rate on the 2025 Credit Facility and 2021 Credit Facility for the nine months ended September 30, 2025, before giving effect to the impact of the interest rate swaps, w as 6.1% and after giving effect to the impact of the interest rate swaps, w as 5.5%. The weighted average interest rate on the 2021 Credit Facility for the nine months ended September 30, 2024, before giving effect to the impact of the interest rate swaps, was 7.2% and after giving effect to the impact of the interest rate swaps, was 2.8%.

The Company’s obligations under the 2025 Credit Facility are guaranteed by certain of the Company’s existing and future direct and indirect subsidiaries, and such obligations are secured by substantially all of the Company’s assets, including the capital stock or other equity interests in those subsidiaries.

As of September 30, 2025, the Company had the following interest rate swap agreements in place:

Effective date |  | Expiration date |  | Notional amount |  |  | Fixed rate |  | Floating rate
5/30/2023 |  | 4/27/2026 |  | $ | 70,000,000 |  |  | 3.880% |  | USD-SOFR
6/5/2024 |  | 6/27/2027 |  | $ | 80,000,000 |  |  | 3.270% |  | USD-SOFR
4/1/2025 |  | 4/27/2028 |  | $ | 50,000,000 |  |  | 3.625% |  | USD-SOFR

Loan and Aircraft Security Agreement—On May 18, 2023, the Company entered into a Loan and Aircraft Security Agreement to finance $10.9 million of the purchase a new aircraft (Aircraft Loan). The Aircraft Loan must be repaid in 60 monthly consecutive installments and all outstanding amounts will become due on May 18, 2028. The Aircraft Loan bears interest subject to 1-month Term SOFR and a coupon of 1.86%. The entire principal balance may be prepaid in full subject to a 3.0%, 2.0% and 1.0% prepayment fee if paid prior to the first, second and third anniversary of the loan, respectively. The aircraft serves as collateral security for the Aircraft Loan.

Th e following is a schedule of the aggregate annual maturities of long-term debt (excluding current portion) presented on the unaudited condensed consolidated statement of financial position as of September 30, 2025, before deferred debt issuance cost of $1.9 million, based on the terms of the 2025 Credit Facility and the Aircraft Loan:

|  | 2025 Credit Facility |  |  |  |  |
|  | Term Loan |  | Revolver |  | Aircraft Loan |  | Total |
2026 |  | $ | 2,500 |  | $ | — |  | $ | 315 |  | $ | 2,815 |
2027 |  |  | 10,000 |  |  | — |  |  | 1,318 |  |  | 11,318 |
2028 |  |  | 10,000 |  |  | — |  |  | 577 |  |  | 10,577 |
2029 |  |  | 10,000 |  |  | — |  |  | 5,000 |  |  | 15,000 |
2030 |  |  | 157,500 |  |  | 107,095 |  |  | — |  |  | 264,595 |
Total |  | $ | 190,000 |  | $ | 107,095 |  | $ | 7,210 |  | $ | 304,305 |

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13. FAIR VALUE OF FINANCIAL INSTRUMENTS

The following financial instruments are measured at fair value on a recurring basis using significant unobservable inputs (Level 3):

| September 30, 2025 |  |  | December 31, 2024 |
Interest rate swap (1) | $ | — |  |  | $ | 1,544 |
Total Assets | $ | — |  |  | $ | 1,544 |
Business acquisitions contingent consideration, current | $ | 15,609 |  |  | $ | 26,872 |
Business acquisitions contingent consideration, long-term | $ | 7,810 |  |  | $ | 6,255 |
Conversion option | $ | — |  |  | $ | 20,224 |
Interest rate swap (1) | $ | 286 |  |  | $ | — |
Total Liabilities | $ | 23,705 |  |  | $ | 53,351 |

_____________________________

(1) Included in other non-current liabilities and other assets in the unaudited condensed consolidated statement of financial position as of September 30, 2025 and audited condensed consolidated statement of financial position as of December 31, 2024, respectively.

The estimated fair value amounts shown above are not necessarily indicative of the amounts that the Company would realize upon disposition, nor do they indicate the Company’s intent or ability to dispose of the financial instrument.

The following table sets forth the Company’s financial instruments that were measured at fair value on a recurring basis:

| Interest Rate Swap |  |  | Total Assets |  |  | Business Acquisitions Contingent Consideration, Current |  |  | Business Acquisitions Contingent Consideration, Long-term |  |  | Conversion Option Related to Series A-2 Preferred Stock |  |  | Interest Rate Swap |  |  | Total Liabilities |
Balance as of December 31, 2023 | $ | 3,461 |  |  | $ | 3,461 |  |  | $ | 3,592 |  |  | $ | 2,448 |  |  | $ | 19,017 |  |  | $ | — |  |  | $ | 25,057 |
Acquisitions |  | — |  |  |  | — |  |  |  | 4,976 |  |  |  | 24,396 |  |  |  | — |  |  |  | — |  |  |  | 29,372 |
Changes in fair value included in earnings |  | (3,461 | ) |  |  | (3,461 | ) |  |  | 131 |  |  |  | 254 |  |  |  | 1,037 |  |  |  | 353 |  |  |  | 1,775 |
Payment of contingent consideration payable |  | — |  |  |  | — |  |  |  | (1,450 | ) |  |  | — |  |  |  | — |  |  |  | — |  |  |  | (1,450 | )
Reclass of long term to short term contingent liabilities |  | — |  |  |  | — |  |  |  | (826 | ) |  |  | 826 |  |  |  | — |  |  |  | — |  |  |  | — |
Balance as of September 30, 2024 | $ | — |  |  | $ | — |  |  | $ | 6,423 |  |  | $ | 27,924 |  |  | $ | 20,054 |  |  | $ | 353 |  |  | $ | 54,754 |
Balance as of December 31, 2024 | $ | 1,544 |  |  | $ | 1,544 |  |  | $ | 26,872 |  |  | $ | 6,255 |  |  | $ | 20,224 |  |  | $ | — |  |  | $ | 53,351 |
Changes in fair value included in earnings |  | (1,544 | ) |  |  | (1,544 | ) |  |  | (231 | ) |  |  | 1,075 |  |  |  | (20,224 | ) |  |  | 286 |  |  |  | (19,094 | )
Payment of contingent consideration payable |  | — |  |  |  | — |  |  |  | (12,100 | ) |  |  | — |  |  |  | — |  |  |  | — |  |  |  | (12,100 | )
Reclass of long term to short term contingent liabilities |  | — |  |  |  | — |  |  |  | (480 | ) |  |  | 480 |  |  |  | — |  |  |  | — |  |  |  | — |
Measurement period adjustment |  | — |  |  |  | — |  |  |  | 1,548 |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 1,548 |
Balance as of September 30, 2025 | $ | — |  |  | $ | — |  |  | $ | 15,609 |  |  | $ | 7,810 |  |  | $ | — |  |  | $ | 286 |  |  | $ | 23,705 |

14. COMMITMENTS AND CONTINGENCIES

Leases—The Company leases office facilities over various terms expiring through 2034. Certain of these operating leases contain rent escalation clauses. The Company also has office equipment leases that expire through 2030 (Not e 6 and 12).

Other Commitments—The Company has commitments under the 2025 Credit Facility, its Aircraft Loan, its equipment line of credit and its lease obligations (Note 6 and 12). The Company has entered into a purchase contract to purchase a total of $4.9 million of equipment over the course of 7 years that commenced on July 1, 2024, subject to a minimum spending requirement per year, measured from the commencement date and each anniversary thereof. The minimum spend requirement is $0.2 million, $0.4 million, and $0.9 million for 2025, 2026, and 2027, respectively, with the remainder subject to mutual agreement after the first three years. Amounts purchased for the three and nine months ended September 30, 2025 were $0.4 million and $0.6 millio n, respectively.

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Contingencies—The Company is subject to purchase price contingencies related to earn-outs associated with certain acquisitions (Note 7 and 13).

Legal—In the normal course of business, the Company is at times subject to pending and threatened legal actions. In management’s opinion, the potential loss resulting from the resolution of these matters is not expected to have a material effect on the unaudited condensed consolidated results of operations, financial position or cash flows of the Company.

15. CONVERTIBLE AND REDEEMABLE SERIES A-2 PREFERRED STOCK

On April 13, 2020, the Company entered into an agreement to issue 17,500 shares of the Convertible and Redeemable Series A-2 Preferred Stock with a par value of $0.0001 per share and a detachable warrant to purchase shares of the Company’s common stock with a 10-year life, in exchange for gross proceeds of $175.0 million, net of $1.3 million debt issuance costs. The Convertible and Redeemable Series A-2 Preferred Stock warrants were exercised in full on July 30, 2020. Dividends on the Convertible and Redeemable Series A-2 Preferred Stock accrued through the date of the Company’s initial public offering on July 23, 2020, and were added to the principal balance outstanding as of that date. All dividends on the Convertible and Redeemable Series A-2 Preferred Stock after that date have been paid in cash. The Company paid dividends on shares of the Convertible and Redeemable Series A-2 Preferred Stock of $1.4 million and $2.8 million during the three months ended September 30, 2025 and September 30, 2024, respectively, and $4.2 million and $8.3 million during the nine months ended September 30, 2025 and 2024, respectively.

The Convertible and Redeemable Series A-2 Preferred Stock terms included the following: (i) no mandatory redemption, (ii) no stated value cash repayment obligation other than in the event of certain defined liquidation events, (iii) only redeemable at the Company’s option, (iv) convertible into common stock beginning in April 2024 at a 15.0% discount to the common stock market price (with a limit of $60.0 million in stated value of Convertible and Redeemable Series A-2 Preferred Stock eligible to be converted in any 60-day period prior to the seventh anniversary of issuance and the amount of stated value of the Convertible and Redeemable Series A-2 Preferred Stock eligible for conversion limited to $60.0 million during year 5 and $120.0 million (which includes the aggregate amount of the stated value of the Convertible and Redeemable Series A-2 Preferred Stock and any accrued but unpaid dividends added to such stated value of any shares of Convertible and Redeemable Series A-2 Preferred Stock converted in year 5) during year 6), (v) 9.0% dividend rate per year with required quarterly cash payments, (vi) in an event of noncompliance, the dividend rate shall increase to 12.0% per annum for the first 90-day period from and including the date the noncompliance event occurred, and thereafter shall increase to 14.0% per annum, (vii) debt incurrence test ratio of 4.5 times, and (viii) minimum repayment amount of $25.0 million.

The Company could, at its option on any one or more dates, redeem all or a minimum portion (the lesser of (i) $25.0 million in aggregate stated value of the Convertible and Redeemable Series A-2 Preferred Stock and (ii) all of the Convertible and Redeemable Series A-2 Preferred Stock then outstanding) of the outstanding Convertible and Redeemable Series A-2 Preferred Stock in cash. In January 2024, the Company redeemed $60.0 million in aggregate stated value of the outstanding Convertible and Redeemable Series A-2 Preferred Stock with cash. On April 1, 2025, the Company redeemed $60.0 million in aggregate stated value of the outstanding Series A-2 Preferred Stock. On July 1, 2025, the Company redeemed the remaining $62.2 million in aggregate stated value of the outstanding Series A-2 Preferred Stock. The Company funded each 2025 redemption with cash on hand and borrowings under the 2025 Credit Facility. Following the July 2025 redemption, no A-2 Preferred Shares remained outstanding. Both 2025 redemptions were reflected, net of applicable excise tax, in the Company's Unaudited Condensed Consolidated Statements of Convertible and Redeemable Series A-2 Preferred Stock and Stockholders’ Equity and resulted in a reduction of temporary equity. The impact of the redemptions is also reflected in the calculation of earnings per share for the three months ended September 30, 2025.

The Convertible and Redeemable Series A-2 Preferred Stock did not meet the definition of a liability pursuant to “ASC 480- Distinguishing Liabilities from Equity.” However, as (i) the instrument was redeemable upon a change of control as defined in the certificate of designations governing the terms of the Convertible and Redeemable Series A-2 Preferred Stock, and (ii) the Company could not have asserted it would have sufficient authorized and unissued shares of common stock to settle all future conversion requests due to the variable conversion terms, the instrument was redeemable upon the occurrence of events that are not solely within the control of the Company, and therefore the Company classified the Convertible and Redeemable Series A-2 Preferred Stock as mezzanine equity prior to the July 2025 redemption of the remaining outstanding shares of A-2 Preferred Stock.

The Convertible and Redeemable Series A-2 Preferred Stock contained a conversion option of the preferred shares to shares of common stock beginning in April 2024. As of September 30, 2025 and December 31, 2024, this conversion embedded feature had a net fair value of $0.0 million, due to the full redemption, and $20.2 million, respectively. The change in net fair value of $(10.6) million and $(20.2) million for the three and nine months ended September 30, 2025, respectively, and $0.5 million and $1.0 million for the three and nine months ended September 30, 2024, respectively, was recorded to other (income) expense.

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16. STOCKHOLDERS’ EQUITY

Employee Equity Incentive Plans

The Company has two plans under which stock-based awards have been issued: (i) the Montrose Amended & Restated 2017 Stock Incentive Plan (2017 Plan) and (ii) the Montrose Amended & Restated 2013 Stock Option Plan (2013 Plan) (collectively the Plans).

The following number of shares were authorized to be issued and available for grant:

| September 30, 2025 |
| 2017 Plan |  |  | 2013 Plan |  |  | Total |
Shares authorized to be issued |  | 8,911,649 |  |  |  | 2,035,219 |  |  |  | 10,946,868 |
Shares available for grant(1) |  | 1,916,777 |  |  |  | — |  |  |  | 1,916,777 |
| September 30, 2024 |
| 2017 Plan |  |  | 2013 Plan |  |  | Total |
Shares authorized to be issued |  | 7,538,276 |  |  |  | 2,036,219 |  |  |  | 9,574,495 |
Shares available for grant(1) |  | 1,651,705 |  |  |  | — |  |  |  | 1,651,705 |

(1) In January 2025 and January 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. Shares available for grant as of September 30, 2024 exclude awards of stock appreciation rights approved in December 2021 that were subject to vesting based on the achievement of certain market conditions (2021 Performance SARs), which had not yet been achieved when these awards were cancelled, effective as of December 31, 2024. See footnote 1 to the table in Common Stock Reserved for Future Issuance in Note 18 below for additional information on stock appreciation rights.

17. NET INCOME (LOSS) PER SHARE

Basic net income (loss) per share is computed by dividing net loss attributable to common stockholders by the weighted average number of common shares outstanding during each period. The Convertible and Redeemable Series A-2 Preferred Stock is considered a participating security during the applicable period. Net losses are not allocated to the Convertible and Redeemable Series A-2 stockholders, as they were not contractually obligated to share in the Company’s losses.

Diluted net income (loss) per share is computed by dividing net income (loss) attributable to common stockholders by the weighted average number of common and dilutive common equivalent shares outstanding for the period using the treasury-stock method or the if-converted method. Potentially dilutive shares are comprised of awards of restricted stock (RSAs), restricted stock units (RSUs), stock appreciation rights (SARs) and shares of common stock underlying stock options outstanding under the Company's stock incentive plans, as applicable. During the three and nine months ended September 30, 2024 there is no difference in the number of shares used to calculate basic and diluted shares outstanding during the applicable period due to the Company’s net loss attributable to common stockholders and potentially dilutive shares being anti-dilutive.

20

The following table summarizes the computation of basic and diluted net income (loss) per share attributable to common stockholders of the Company:

|  | Three Months Ended September 30, |  |  | Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 |  |  | 2025 |  |  | 2024 |
Net income (loss) |  | $ | 8,378 |  |  | $ | (10,564 | ) |  | $ | 7,375 |  |  | $ | (34,091 | )
Convertible and Redeemable Series A-2 Preferred Stock dividend |  |  | — |  |  |  | (2,750 | ) |  |  | (4,150 | ) |  |  | (8,314 | )
Net income (loss) attributable to common stockholders |  |  | 8,378 |  |  |  | (13,314 | ) |  |  | 3,225 |  |  |  | (42,405 | )
Weighted average common shares outstanding |  |  |  |  |  |  |  |  |  |  |  |
Weighted average common shares outstanding - basic |  |  | 35,300 |  |  |  | 34,242 |  |  |  | 35,003 |  |  |  | 32,647 |
Effect of dilutive stock options |  |  | 1,390 |  |  |  | — |  |  |  | 1,243 |  |  |  | — |
Effect of dilutive restricted stock |  |  | 3,245 |  |  |  | — |  |  |  | 3,301 |  |  |  | — |
Diluted |  |  | 39,935 |  |  |  | 34,242 |  |  |  | 39,547 |  |  |  | 32,647 |
Net income (loss) per share attributable to common stockholders |  |  |  |  |  |  |  |  |  |  |  |
Basic |  | $ | 0.24 |  |  | $ | (0.39 | ) |  | $ | 0.09 |  |  | $ | (1.30 | )
Diluted |  | $ | 0.21 |  |  | $ | (0.39 | ) |  | $ | 0.08 |  |  | $ | (1.30 | )

The following common stock equivalents were excluded from the calculation of dilute d net income (loss) per share attributable to common stockholders for the nine months ended September 30, 2025 and the three and nine months ended September 30, 2024 because their effect would have been anti-dilutive:

|  | September 30, |
|  | 2025(1) |  |  | 2024(1) |
Stock options |  |  | — |  |  |  | 3,059,061 |
Restricted stock |  |  | — |  |  |  | 2,629,026 |
Series A-2 Preferred Stock |  |  | 5,353,478 |  |  |  | 4,448,404 |
SARs(2) |  |  | — |  |  |  | 3,000,000 |

_____________________________

(1) Includes 2,950,220 and 7,891,144 common stock equivalents that are out of the money as of September 30, 2025 and September 30, 2024, respectively.

(2) 2021 Performance SARs were cancelled effective as of December 31, 2024.

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 |

21

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.

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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.

19. SEGMENT INFORMATION

The Company has six operating units that aggregate into three reportable segments: Assessment, Permitting and Response, Measurement and Analysis, and Remediation and Reuse. These segments are monitored separately by management for performance against budget and prior year and are consistent with internal financial reporting. The Company’s operating segments are organized based upon primary services provided, the nature of the production process, types of customers, methods used to distribute the products, and the nature of the regulatory environment. Refer to Note 1 for description of each reportable segment.

Our Chief Executive Officer, who serves as the Chief Operating Decision Maker (CODM), reviews Segment Adjusted EBITDA in the annual budget and forecasting process. The CODM considers budget-to-actual variances on a quarterly basis when making decisions about the allocation of Company resources depending on the needs of each segment and the availability of resources. Segment Adjusted EBITDA is the calculated Company’s Earnings before Interest, Tax, Depreciation and Amortization (EBITDA), adjusted to exclude certain transactions such as stock-based compensation, acquisition costs, and fair value changes in financial instruments, amongst others. The CODM does not review segment assets as a measure of segment performance.

Corporate and Other includes costs associated with general corporate overhead (including executive, legal, finance, safety, human resources, marketing and IT related costs) that are not directly related to supporting operations. Overhead costs that are directly related to supporting operations (such as insurance, software, licenses, shared services and payroll processing costs) are allocated to the operating segments on a basis that reasonably approximates an estimate of the use of these services, and are included in Segment Expenses in the table below.

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Segment Revenues, Segment Expenses and Segment Adjusted EBITDA were as follows:

|  | Three Months Ended September 30, |
|  | 2025 |  |  | 2024 |
(in thousands) |  | Segment Revenues |  |  | Segment Expenses |  |  | Segment Adjusted EBITDA |  |  | Segment Revenues |  |  | Segment Expenses |  |  | Segment Adjusted EBITDA |
Assessment, Permitting and Response |  | $ | 91,081 |  |  | $ | 70,645 |  |  | $ | 20,436 |  |  | $ | 52,019 |  |  | $ | 40,831 |  |  | $ | 11,188 |
Measurement and Analysis |  |  | 62,958 |  |  |  | 45,675 |  |  |  | 17,283 |  |  |  | 58,583 |  |  |  | 45,213 |  |  |  | 13,370 |
Remediation and Reuse |  |  | 70,849 |  |  |  | 61,437 |  |  |  | 9,412 |  |  |  | 68,085 |  |  |  | 56,430 |  |  |  | 11,655 |
Total Reportable Segments |  | $ | 224,888 |  |  |  |  |  | $ | 47,131 |  |  | $ | 178,687 |  |  |  |  |  | $ | 36,213 |
|  | Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 |
(in thousands) |  | Segment Revenues |  |  | Segment Expenses |  |  | Segment Adjusted EBITDA |  |  | Segment Revenues |  |  | Segment Expenses |  |  | Segment Adjusted EBITDA |
Assessment, Permitting and Response |  | $ | 248,144 |  |  | $ | 189,581 |  |  | $ | 58,563 |  |  | $ | 164,043 |  |  | $ | 123,955 |  |  | $ | 40,088 |
Measurement and Analysis |  |  | 184,783 |  |  |  | 135,429 |  |  |  | 49,354 |  |  |  | 158,889 |  |  |  | 126,656 |  |  |  | 32,233 |
Remediation and Reuse |  |  | 204,338 |  |  |  | 178,969 |  |  |  | 25,369 |  |  |  | 184,405 |  |  |  | 158,811 |  |  |  | 25,594 |
Total Reportable Segments |  | $ | 637,265 |  |  |  |  |  | $ | 133,286 |  |  | $ | 507,337 |  |  |  |  |  | $ | 97,915 |

Presented below is a reconciliation of the Company’s segment measure to income (loss) before expense from income taxes:

|  | For the Three Months Ended September 30, |  |  | For the Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 |  |  | 2025 |  |  | 2024 |
Total Reportable Segments |  | $ | 47,131 |  |  | $ | 36,213 |  |  | $ | 133,286 |  |  | $ | 97,915 |
Corporate and Other |  |  | (13,470 | ) |  |  | (7,901 | ) |  |  | (41,010 | ) |  |  | (29,367 | )
Interest expense, net |  |  | (5,039 | ) |  |  | (4,137 | ) |  |  | (14,872 | ) |  |  | (11,420 | )
Depreciation and amortization |  |  | (12,958 | ) |  |  | (13,240 | ) |  |  | (39,015 | ) |  |  | (37,408 | )
Stock-based compensation |  |  | (9,220 | ) |  |  | (11,763 | ) |  |  | (33,777 | ) |  |  | (34,866 | )
Acquisition costs (1) |  |  | (754 | ) |  |  | (2,764 | ) |  |  | (1,790 | ) |  |  | (6,371 | )
Fair value changes in financial instruments |  |  | 10,354 |  |  |  | (3,946 | ) |  |  | 18,394 |  |  |  | (4,851 | )
Fair value changes in business acquisition contingencies |  |  | (13 | ) |  |  | (143 | ) |  |  | (844 | ) |  |  | (385 | )
Expenses related to financing transactions |  |  | (29 | ) |  |  | (41 | ) |  |  | (303 | ) |  |  | (280 | )
Discontinued Specialty Lab |  |  | — |  |  |  | (96 | ) |  |  | — |  |  |  | (692 | )
Other losses or expenses(2) |  |  | (343 | ) |  |  | (1,378 | ) |  |  | (1,554 | ) |  |  | (1,886 | )
Income (loss) before expense from income taxes |  | $ | 15,659 |  |  | $ | (9,196 | ) |  | $ | 18,515 |  |  | $ | (29,611 | )

__________________________

(1) Includes financial and tax diligence, consulting, legal, valuation, accounting, travel and acquisition-related incentives related to our acquisition and integration activity.

(2) The three months ended September 30, 2025 consist primarily of severance costs. The nine months ended September 30, 2025 consist primarily of the aforementioned severance costs, non-recurring costs incurred to restructure the Company's renewable energy business, third party expenses associated with the independent review and analysis of assertions in a short seller report regarding the Company, and costs to centralize certain back-office functions. The three and nine months ended September 30, 2024 consist primarily of non-recurring costs to centralize certain back-office functions. The nine months ended September 30, 2024 also include costs associated with a lease abandonment.

The following table presents revenues by geographic location:

|  | For the Three Months Ended September 30, |  |  | For the Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 |  |  | 2025 |  |  | 2024 |
United States |  | $ | 183,578 |  |  | $ | 139,574 |  |  | $ | 528,525 |  |  | $ | 405,428 |
Canada |  |  | 33,509 |  |  |  | 31,639 |  |  |  | 85,857 |  |  |  | 81,517 |
Other international |  |  | 7,801 |  |  |  | 7,473 |  |  |  | 22,883 |  |  |  | 20,391 |
Total revenue |  | $ | 224,888 |  |  | $ | 178,687 |  |  | $ | 637,265 |  |  | $ | 507,337 |

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The following table presents long-lived assets by geographic location:

|  | September 30, |  |  | December 31, |
|  | 2025 |  |  | 2024 |
United States |  | $ | 57,087 |  |  | $ | 57,730 |
Canada |  |  | 4,517 |  |  |  | 5,070 |
Other international |  |  | 1,348 |  |  |  | 976 |
Total property and equipment—net |  | $ | 62,952 |  |  | $ | 63,776 |

20. RELATED-PARTY TRANSACTIONS

The Company d id no t ha ve any material related party transactions during the three and nine months ended September 30, 2025 and September 30, 2024.

21. DEFINED CONTRIBUTION PLAN

On January 1, 2014, the Company established the Montrose Environmental Group 401(k) Savings Plan (the 401(k) Savings Plan). As of September 30, 2025, and December 31, 2024, plan participants may defer up to 85.0% of their eligible wages for the year, up to the Internal Revenue Service dollar limit and catch-up contribution allowed by law. The Company provided employer matching contributions equal to 100.0% of the first 3.0% of the participant’s compensation and 50.0% of the participant’s elective deferrals that exceed 3.0% but do not exceed 5.0% of the participant’s compensation. Employer contributions under the 401(k) Savings Plan were $2.6 million and $7.8 million for the three and nine months ended September 30, 2025, respectively, and $2.1 million and $7.0 million for the three and nine months ended September 30, 2024, respectively.

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FORWARD-LOOKING STATEMENTS

This Quarterly Report on Form 10-Q contains “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, or the Securities Act, and Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act. These forward-looking statements relate to matters such as our industry, business strategy, goals and expectations concerning our market position, future operations, margins, profitability, capital expenditures, liquidity, capital resources and other financial and operating information. We use words such as “anticipate,” “assume,” “believe,” “contemplate,” “continue,” “could,” “estimate,” “expect,” “future,” “intend,” “may,” “plan,” “position,” “potential,” “predict,” “project,” “seek,” “should,” “target,” “will” and similar terms and phrases to identify forward-looking statements in this filing. All of our forward-looking statements are subject to risks and uncertainties that may cause actual results to differ materially from those that we are expecting, including:

•
general global economic, business and other conditions, including inflationary and interest rate pressures and tariffs and other trade tensions, the cyclical nature of our industry and the significant fluctuations in events that impact our business;
•
the parts of our business that depend on difficult to predict natural or manmade events and the fluctuations in our revenue and customer concentration as a result thereof;
•
the highly competitive nature of our business;
•
our ability to execute on our acquisition strategy and successfully integrate and realize benefits from our acquisitions;
•
any failure in or breach of our networks and systems or other forms of cyber-attack;
•
our ability to promote and develop our brands;
•
our ability to maintain and expand our client base;
•
our ability to maintain necessary accreditations and other authorizations in varying jurisdictions;
•
significant environmental governmental regulation and liabilities;
•
our ability to attract and retain qualified managerial and skilled technical personnel;
•
safety-related issues;
•
allegations regarding compliance with professional standards, duties and statutory obligations and our ability to provide accurate results;
•
the lack of formal long-term agreements with many of our clients;
•
our ability to adapt to changing technology, industry standards or regulatory requirements, including emerging environmental, social and governance requirements;
•
government clients and contracts;
•
our ability to maintain our prices and manage costs;
•
our ability to protect our intellectual property or claims that we infringe on the intellectual property rights of others;
•
laws and regulations regarding handling of confidential information;
•
our international operations;
•
product related risks; and
•
additional factors discussed in our filings with the Securities and Exchange Commission, or the SEC.

The forward-looking statements in this Quarterly Report on Form 10-Q are based on historical performance and management’s current plans, estimates and expectations in light of information currently available to us and are subject to uncertainty and changes in circumstances. There can be no assurance that future developments affecting us will be those that we have anticipated. Actual results or outcomes may differ materially from these expectations due to changes in global, regional or local political, economic, business, competitive, market, regulatory and other factors, many of which are beyond our control, as well as the other factors described in Item 1A. “Risk Factors” in our Annual Report on Form 10-K for the year ended December 31, 2024 filed with the SEC on March 3, 2025, or the 2024 Form 10-K, as supplemented in Part II, Item 1A. “Risk Factors” in our Quarterly Report on Form 10-Q for the quarter ended March 31, 2025, or the Q1 2025 Form 10-Q.

Additional factors or events that could cause our actual results or outcomes to differ may also emerge from time to time, and it is not possible for us to predict all of them. In addition, historical, current and forward-looking sustainability-related statements may be based on standards for measuring progress that are still developing, internal controls and processes that continue to evolve, and assumptions that are subject to change in the future. Should one or more of these risks or uncertainties materialize, or should any of our assumptions prove to be incorrect, our actual results

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or outcomes may vary in material respects from what we may have expressed or implied by any forward-looking statement and, therefore, you should not regard any forward-looking statement as a representation or warranty by us or any other person that we will successfully achieve the expectation, plan or objective expressed in such forward-looking statement in any specified time frame, or at all. We caution that you should not place undue reliance on any of our forward-looking statements. Any forward-looking statement made by us speaks only as of the date on which we make it. We undertake no obligation to publicly update any forward-looking statement, whether as a result of new information, future developments or otherwise, except as may be required by applicable securities laws.

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Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations.

The following discussion and analysis of our financial condition and results of operations should be read in conjunction with our historical audited and unaudited consolidated financial statements and related notes and other information included elsewhere in this filing and our other filings with the SEC, including our unaudited condensed consolidated financial statements and the accompanying notes as of and for the three and nine months ended September 30, 2025 and September 30, 2024 included in Part I, Item 1. “Financial Statements” in this Quarterly Report on Form 10-Q. This discussion contains forward-looking statements that involve risks and uncertainties. Our actual results could differ materially from such forward-looking statements. Factors that could cause or contribute to those differences include, but are not limited to, those identified below and those discussed in the section entitled “Forward-Looking Statements”, and elsewhere in this filing and our other filings with the SEC, including in Item 1A. Risk Factors in the 2024 Form 10-K and Part II, Item 1A. Risk Factors in the Q1 2025 Form 10-Q.

Overview

Since our inception in 2012, our mission has been to help clients and communities meet their environmental goals and needs. According to data derived from a 2024 Environmental Industry Study prepared by Environmental Business International, Inc., or EBI, which we commissioned, the global environmental industry is estimated to be approximately $1.6 trillion, with $540.0 billion concentrated in the United States.

Our Segments

We provide environmental services to our clients through three business segments—Assessment, Permitting and Response, Measurement and Analysis and Remediation and Reuse. For more information on each of our operating segments, see Item 1. “Business” in the 2024 Form 10-K.

Assessment, Permitting and Response

Assessment, Permitting and Response segment provides scientific advisory and consulting services to support environmental assessments, environmental emergency response and recovery, toxicology consulting and environmental audits and permits for current operations, facility upgrades, new projects, decommissioning projects and development projects. We work closely with clients to navigate the regulatory process at the local, state, provincial and federal levels, identify the potential environmental and political impacts of their decisions and develop practical mitigation approaches, as needed. In addition to environmental toxicology and given our expertise in helping businesses plan for and respond to disruptions, our scientists and response teams have helped clients navigate their preparation for and response to emergency response situations.

Measurement and Analysis

Measurement and Analysis segment is one of the largest providers of environmental testing and laboratory services in North America. Our highly credentialed teams test and analyze air, water and soil to determine concentrations of contaminants, as well as the toxicological impact of contaminants on flora, fauna and human health. Our offerings include source and ambient air testing and monitoring, leak detection, and advanced multi-media laboratory services, including air, soil, stormwater, wastewater and drinking water analysis.

Remediation and Reuse

Remediation and Reuse segment provides clients with engineering, design, and implementation services, primarily (i) treatment technologies which treat contaminated water or create renewable energy from waste, or (ii) soil remediation. Our employees, including engineers, scientists and consultants, provide these services to assist our clients in designing solutions, managing products and mitigating environmental risks and liabilities at their locations. We do not own the properties or facilities at which we implement these projects or the underlying liabilities, nor do we own material amounts of the equipment used in projects.

These operating segments have been structured and organized to align with how we view and manage the business with the full lifecycle of our clients’ targeted environmental concerns and needs in mind. Within each segment, we cover similar service offerings, regulatory frameworks, internal operating structures and client types. Corporate activities not directly related to segment performance, including general corporate expenses, interest and taxes, are reported separately.

Key Factors that Affect Our Business and Our Results

Our operating results and financial performance are influenced by a variety of internal and external trends and other factors. Some of the more important factors are discussed briefly below.

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Acquisitions

Although we have temporarily paused acquisitions, we have been, and expect to continue to be, an acquisitive company. Acquisitions have expanded our environmental service capabilities across all three segments, our access to technology, as well as our geographic reach in the United States, Canada, Europe and Australia. The table below sets forth the number of acquisitions completed, revenues generated by and the percentage of total revenues attributable to those acquisitions completed during the three and nine months ended September 30, 2025 and September 30, 2024:

|  | Three Months Ended September 30, |  |  | Nine Months Ended September 30, |
(Revenues in thousands) |  | 2025 |  |  | 2024 |  |  | 2025 |  |  | 2024 |
Acquisitions completed |  |  | — |  |  |  | 2 |  |  |  | — |  |  |  | 6 |
Revenues attributable to acquisitions completed in the period |  | $ | — |  |  | $ | 4,304 |  |  | $ | — |  |  | $ | 26,600 |
Percentage of revenues |  |  | 0.0 | % |  |  | 2.4 | % |  |  | 0.0 | % |  |  | 5.2 | %

Revenues from acquired companies exclude intercompany revenues from revenue synergies realized between business lines within operating segments, as these are eliminated at the consolidated segment and Company level. We expect our revenue growth to continue to be driven in significant part by acquisitions. See Note 7 to our unaudited condensed consolidated financial statements included in Part I, Item 1. “Financial Statements.”

As a result of our acquisitions, goodwill and other intangible assets represent a significant proportion of our total assets, and amortization of intangible assets has historically been a significant expense. Our historical financial statements also include other acquisition-related costs, including costs relating to external legal support, diligence and valuation services and other transaction and integration-related matters. In addition, in any year gains and losses from changes in the fair value of business acquisition contingencies such as earn-outs could be significant. The amount of each for the three and nine months ended September 30, 2025 and September 30, 2024, was:

|  | Three Months Ended September 30, |  |  | Nine Months Ended September 30, |
(in thousands) |  | 2025 |  |  | 2024 |  |  | 2025 |  |  | 2024 |
Amortization expense |  | $ | 7,275 |  |  | $ | 8,978 |  |  | $ | 22,991 |  |  | $ | 24,621 |
Acquisition-related costs |  |  | 754 |  |  |  | 2,764 |  |  |  | 1,790 |  |  |  | 6,370 |
Fair value changes in business acquisition contingencies |  |  | (13 | ) |  |  | (143 | ) |  |  | (844 | ) |  |  | (385 | )

We expect that amortization of identifiable intangible assets and other acquisition-related costs, assuming we continue to acquire, will continue to be significant.

During the three months ended September 30, 2025, we made a contingent consideration cash payment of $1.2 million for Vandrensning. During the three months ended September 30, 2024, no contingent consideration payments were made.

During the nine months ended September 30, 2025, we made contingent consideration payments of $11.8 million for Epic, SensibleIoT, LLC (Sensible), and Vandrensning, of which $5.2 million was paid in cash, and the remaining $6.6 million was paid in the Company's common stock. During the nine months ended September 30, 2024, we made earn-out payments of $1.5 million in connection with our acquisition of Huco Consulting, Inc., of which, $0.4 million was paid in cash, and the remaining $1.1 million in the Company's common stock.

In connection with certain of our acquisitions, we may make up to $23.4 million in aggregate earn-out payments between the years 2025 and 2027, of which up to $10.4 million may be paid only in cash, up to $2.8 million may be paid only in common stock and up to $10.2 million may be paid, at our option, in cash or common stock. See Note 7 to our unaudited condensed consolidated financial statements included in Part I, Item 1. “Financial Statements.”

Organic Growth

We define organic growth as the change in revenues excluding revenues from (i) our environmental emergency response business, (ii) acquisitions for the first twelve months following the date of acquisition, and (iii) businesses held for sale, disposed of or discontinued. Management uses organic growth as one of the means by which it assesses our results of operations. Organic growth is not, however, a measure of revenue growth calculated in accordance with U.S. generally accepted accounting principles, or GAAP, and should be considered in conjunction with revenue growth calculated in accordance with GAAP. We have grown organically over the long term and expect to continue to do so.

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Revenue Mix

Our segments and our business lines within each segment generate different levels of profitability and, accordingly, shifts in the mix of revenues between segments can impact our consolidated reported net income or loss, net income or loss margin, Segment Adjusted EBITDA and Segment Adjusted EBITDA margin from quarter to quarter and year to year. Inter-company revenues between business lines within segments have been eliminated. See Note 19 to our unaudited condensed consolidated financial statements included in Part 1, Item 1 “Financial Statements.”

Our revenues and certain expenses, including selling, general and administrative expense, vary from period to period due primarily to changes in organic growth, the incremental contribution from recent acquisitions and strategic decisions we may make from time to time. When we refer to changes driven by organic growth, we are referring to the contribution from businesses that have been part of Montrose for more than 12 months, with certain limited exclusions as discussed in greater detail above. In a given reporting period, when we refer to revenue changes driven by acquisitions, we are referring to the revenue contribution from any acquisition from its closing date through the first 12 months of that acquisition, at which point any subsequent revenue contribution therefrom would be organic.

Financing Costs

Financing costs are driven by interest incurred on our outstanding borrowings under our senior secured credit facilities, as well as fees paid on the unutilized capacity of the facility and outstanding letters of credit issued under the facility. Interest is also incurred on outstanding borrowings under the Aircraft Loan and amounts outstanding under our capital lease facilities. Financing costs also include the amortization or write-offs of deferred debt issuance costs and amounts paid under our interest rate swaps. Amounts received related to our interest rate swaps are netted off of Financing Costs.

Interest expense, net was $5.0 million and $14.9 million in the three and nine months ended September 30, 2025, respectively, and $4.1 million and $11.4 million in the three and nine months ended September 30, 2024, respectively. We expect interest expense to remain a significant cost as we continue to leverage our 2025 Credit Facility to support our operations and future acquisitions. We also leveraged our 2025 Credit Facility to pay a portion of the redemption price for the Series A-2 preferred stock in April and July 2025.

In February 2025, we refinanced our 2021 Credit Facility and replaced it with a new 2025 Credit Facility. See Note 12 to our unaudited condensed consolidated financial statements included in Part 1, Item 1 “Financial Statements” and “Liquidity and Capital Resources.”

Corporate and Operational Infrastructure Investments

Our historical operating results reflect the impact of our ongoing investments in our corporate infrastructure to support our growth. We have made and expect to continue to make investments in our business platform that we believe have laid the foundation for continued growth. Investments in logistics, quality, risk management, sales and marketing, safety, human resources, research and development, finance and information technology and other areas enable us to support continued growth. These investments should allow us to improve our margins over time.

Seasonality

Because demand for environmental services is not driven by specific or predictable patterns in one or more fiscal quarters, our business is better assessed based on annual results. Additionally, due to the field-based nature of certain of our services, weather patterns generally impact our field-based teams’ ability to operate in the winter months. As a result, our operating results in our Measurement and Analysis segment and our Remediation and Reuse segment, experience some quarterly variability with generally lower revenues and lower earnings in the first and fourth quarters and typically higher overall revenues and earnings in the second and third quarters. As we continue to grow and expand into new geographies and service lines, quarterly variability in our Measurement and Analysis and Remediation and Reuse segments may deviate from historical trends.

Earnings Volatility

In addition to the impact of seasonality on earnings, our emergency response business exposes us to potentially significant revenue and earnings fluctuations tied to large environmental emergency response projects following an incident or natural disaster or more broad scale events. Total revenue from emergency response related services was $11.5 million and $12.0 million for the three months ended September 30, 2025 and 2024, respectively, and $73.9 million and $40.6 million for the nine months ended September 30, 2025 and 2024, respectively. The higher than normal emergency response and environmental services revenue in the nine months ended September 30, 2025 was primarily driven by one large emergency response project. Demand for environmental emergency response services remains difficult to predict and as a result, revenues and earnings in the current and prior years, or specific quarters or year-to-date periods within a given year, may not be indicative of future results, making those periods particularly difficult comparisons for future periods. Earnings volatility is also driven by the timing of large projects, particularly in our Remediation and Reuse segment, and the impact of acquisitions. As a result of these factors, and because demand for

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environmental services is not driven by specific or predictable patterns in one or more fiscal quarters, our business is better assessed based on annual results.

Results of Operations

The Three And Nine Months Ended September 30, 2025 Compared to the Three And Nine Months Ended September 30, 2024

|  | Three Months Ended September 30, |  |  | Nine Months Ended September 30, |
(in thousands, except per share data) |  | 2025 |  |  | 2024 |  |  | 2025 |  |  | 2024 |
Revenues |  | $ | 224,888 |  |  | $ | 178,687 |  |  | $ | 637,265 |  |  | $ | 507,337 |
Cost of revenues (exclusive of depreciation and amortization) |  |  | 136,284 |  |  |  | 105,596 |  |  |  | 377,492 |  |  |  | 306,239 |
Selling, general and administrative expense |  |  | 65,696 |  |  |  | 60,869 |  |  |  | 205,611 |  |  |  | 177,182 |
Fair value changes in business acquisition contingencies |  |  | 13 |  |  |  | 143 |  |  |  | 844 |  |  |  | 385 |
Depreciation and amortization |  |  | 12,958 |  |  |  | 13,240 |  |  |  | 39,015 |  |  |  | 37,408 |
Income (loss) from operations |  |  | 9,937 |  |  |  | (1,161 | ) |  |  | 14,303 |  |  |  | (13,877 | )
Other income (expense), net |  |  | 10,761 |  |  |  | (3,898 | ) |  |  | 19,084 |  |  |  | (4,314 | )
Interest expense, net |  |  | (5,039 | ) |  |  | (4,137 | ) |  |  | (14,872 | ) |  |  | (11,420 | )
Income (loss) before income taxes |  |  | 15,659 |  |  |  | (9,196 | ) |  |  | 18,515 |  |  |  | (29,611 | )
Income tax expense |  |  | 7,281 |  |  |  | 1,368 |  |  |  | 11,140 |  |  |  | 4,480 |
Net income (loss) |  | $ | 8,378 |  |  | $ | (10,564 | ) |  | $ | 7,375 |  |  | $ | (34,091 | )
Series A-2 dividend payment |  |  | — |  |  |  | (2,750 | ) |  |  | (4,150 | ) |  |  | (8,314 | )
Net income (loss) attributable to common stockholders |  | $ | 8,378 |  |  | $ | (13,314 | ) |  | $ | 3,225 |  |  | $ | (42,405 | )
Weighted average common shares outstanding |  |  |  |  |  |  |  |  |  |  |  |
Basic |  |  | 35,300 |  |  |  | 34,242 |  |  |  | 35,003 |  |  |  | 32,647 |
Diluted |  |  | 39,935 |  |  |  | 34,242 |  |  |  | 39,547 |  |  |  | 32,647 |
Net income (loss) per share attributable to common stockholders |  |  |  |  |  |  |  |  |  |  |  |
Basic |  | $ | 0.24 |  |  | $ | (0.39 | ) |  | $ | 0.09 |  |  | $ | (1.30 | )
Diluted |  | $ | 0.21 |  |  | $ | (0.39 | ) |  | $ | 0.08 |  |  | $ | (1.30 | )

Revenues

|  | Three Months Ended September 30, |  |  | Change |  |  | Nine Months Ended September 30, |  |  | Change |
(in thousands, except %) |  | 2025 |  |  | 2024 |  |  | $ |  |  | % |  |  | 2025 |  |  | 2024 |  |  | $ |  |  | % |
Revenues |  | $ | 224,888 |  |  | $ | 178,687 |  |  | $ | 46,201 |  |  |  | 25.9 | % |  | $ | 637,265 |  |  | $ | 507,337 |  |  | $ | 129,928 |  |  |  | 25.6 | %

Revenue for the three months ended September 30, 2025 increased $46.2 million or 25.9% as compared to the three months ended September 30, 2024. The increase was primarily driven by strong organic growth of $44.9 million driven primarily by the Assessment, Permitting and Response segment, which benefited from remediation consulting work cross sold from an initial emergency response incident, and $2.4 million from acquisitions. Environmental emergency response revenues were $11.5 million in the three months ended September 30, 2025, compared to $12.0 million in the three months ended September 30, 2024.

Revenue for the nine months ended September 30, 2025 increased $129.9 million or 25.6% as compared to the nine months ended September 30, 2024. The increase was primarily driven by strong organic growth of $73.3 million across all three segments, $33.3 million higher emergency response revenue, and $25.0 million from acquisitions. Revenue from environmental response was $73.9 million in the nine months ended September 30, 2025 compared to $40.6 million in the nine months ended September 30, 2024.

See “—Segment Results of Operations” below for revenue by segment analysis.

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Cost of Revenues

|  | Three Months Ended September 30, |  |  | Change |  |  | Nine Months Ended September 30, |  |  | Change |
(in thousands, except %) |  | 2025 |  |  | 2024 |  |  | $ |  |  | % |  |  | 2025 |  |  | 2024 |  |  | $ |  |  | % |
Cost of revenues (exclusive of depreciation and amortization) |  | $ | 136,284 |  |  | $ | 105,596 |  |  | $ | 30,688 |  |  |  | 29.1 | % |  | $ | 377,492 |  |  | $ | 306,239 |  |  | $ | 71,253 |  |  |  | 23.3 | %
Cost of revenue as a % of revenue |  |  | 60.6 | % |  |  | 59.1 | % |  |  |  |  |  |  |  |  | 59.2 | % |  |  | 60.4 | % |  |  |  |  |  |

Cost of revenues consists of all direct costs required to provide services, including fixed and variable direct labor costs, equipment purchases, and rental and other outside services, field and lab supplies, vehicle costs and travel-related expenses. Variable costs of revenues generally follow the same trends as revenue, while fixed costs tend to change primarily as a result of acquisitions.

Cost of revenues for the three months ended September 30, 2025 compared to the three months ended September 30, 2024 increased by $30.7 million or 29.1% driven primarily by the increase in revenues. Cost of revenues as a percentage of revenue for the three months ended September 30, 2025 was 60.6%, compared to 59.1% for the three months ended September 30, 2024. This increase was driven primarily by an increase in subcontract costs as a percentage of total project costs.

Cost of revenues for the nine months ended September 30, 2025 compared to the nine months ended September 30, 2024 increased by $71.3 million or 23.3% driven primarily by the increase in revenues. Cost of revenues as a percentage of revenue for the nine months ended September 30, 2025 was 59.2%, compared to 60.4% for the nine months ended September 30, 2024. This improvement was driven primarily by business mix in our Assessment, Permitting and Response segment, as high margin emergency response revenues were a greater percentage of total revenues, and operating leverage across all business lines within our Measurement and Analysis businesses.

Selling, General and Administrative Expense

|  | Three Months Ended September 30, |  |  | Change |  |  | Nine Months Ended September 30, |  |  | Change |
(in thousands, except %) |  | 2025 |  |  | 2024 |  |  | $ |  |  | % |  |  | 2025 |  |  | 2024 |  |  | $ |  |  | % |
Selling, general and administrative expense |  | $ | 65,696 |  |  | $ | 60,869 |  |  | $ | 4,827 |  |  |  | 7.9 | % |  | $ | 205,611 |  |  | $ | 177,182 |  |  | $ | 28,429 |  |  |  | 16.0 | %

Selling, general and administrative expense consists of general corporate overhead, including executive, legal, finance, safety, risk management, human resource, marketing and information technology related costs, as well as indirect operational costs of labor, rent, insurance and stock-based compensation.

Selling, general and administrative expense for the three months ended September 30, 2025 compared to the three months ended September 30, 2024 increased $4.8 million or 7.9% primarily due to an increase of $2.2 million in labor costs, mainly driven by a $2.7 million increase in bonus accrual as a result of better than expected performance in the third quarter, and a $1.6 million increase in bad debt expense primarily driven by an increase in aged receivables from the City of Tustin. Selling, general and administrative expense as a percentage of revenues decreased to 29.2% from 34.1% in the comparable period.

Selling, general and administrative expense for the nine months ended September 30, 2025 compared to the nine months ended September 30, 2024 increased $28.4 million or 16.0% primarily due to an increase of $19.4 million in labor costs mainly driven by a $10.6 million increase in bonus accrual, and a $7.1 million increase in bad debt expense, primarily driven by the same factor described above. Selling, general and administrative expense as a percentage of revenues decreased to 32.3% from 34.9% in the comparable period.

See Part I, Item 3. “Quantitative and Qualitative Disclosures About Market Risk” for additional information regarding the impact of inflation on our business.

Depreciation and Amortization

|  | Three Months Ended September 30, |  |  | Change |  |  | Nine Months Ended September 30, |  |  | Change |
(in thousands, except %) |  | 2025 |  |  | 2024 |  |  | $ |  |  | % |  |  | 2025 |  |  | 2024 |  |  | $ |  |  | % |
Depreciation and amortization |  | $ | 12,958 |  |  | $ | 13,240 |  |  | $ | (282 | ) |  |  | (2.1 | %) |  | $ | 39,015 |  |  | $ | 37,408 |  |  | $ | 1,607 |  |  |  | 4.3 | %

Depreciation and Amortization for the three months ended September 30, 2025 remained relatively consistent with the three months ended September 30, 2024 primarily due to the absence of significant changes in the underlying property and equipment and intangible asset base.

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Depreciation and Amortization for the nine months ended September 30, 2025 increased compared to the nine months ended September 30, 2024 primarily as a result of higher property and equipment balances.

See Notes 5 and 6 to our unaudited condensed consolidated financial statements included in Part 1, Item 1. “Financial Statements.”

Other Income (Expense), Net

|  | Three Months Ended September 30, |  |  | Change |  |  | Nine Months Ended September 30, |  |  | Change |
(in thousands, except %) |  | 2025 |  |  | 2024 |  |  | $ |  |  | % |  |  | 2025 |  |  | 2024 |  |  | $ |  |  | % |
Other income (expense), net |  | $ | 10,761 |  |  | $ | (3,898 | ) |  | $ | 14,659 |  |  |  | (376 | %) |  | $ | 19,084 |  |  | $ | (4,314 | ) |  | $ | 23,398 |  |  |  | (542 | %)

Other income (expense), net for the three months ended September 30, 2025 was comprised of a fair value gain of $10.6 million related to the Series A-2 preferred stock conversion option, partially offset by losses of $0.2 million related to a fair value adjustment on our interest rate swaps. Other income (expense), net for the three months ended September 30, 2024 was comprised of losses of $3.5 million related to a fair value adjustment on our interest rate swaps and a $0.5 million charge related to a fair value adjustment on the Series A-2 preferred stock conversion option, partially offset by $0.8 million of other non-operating income.

Other income (expense), net for the nine months ended September 30, 2025 was comprised of a fair value gain of $20.2 million related to the Series A-2 preferred stock conversion option, partially offset by losses of $1.8 million related to a fair value adjustment on our interest rate swaps. Other income (expense), net for the nine months ended September 30, 2024 was comprised of losses of $3.8 million related to a fair value adjustment on our interest rate swaps and a $1.0 million charge related to a fair value adjustment on the Series A-2 preferred stock conversion option, partially offset by $0.5 million of other non-operating income.

See Notes 13 and 15 to our unaudited condensed consolidated financial statements included in Part 1, Item 1. “Financial Statements.”

Interest Expense, Net

|  | Three Months Ended September 30, |  |  | Change |  |  | Nine Months Ended September 30, |  |  | Change |
(in thousands, except %) |  | 2025 |  |  | 2024 |  |  | $ |  |  | % |  |  | 2025 |  |  | 2024 |  |  | $ |  |  | % |
Interest expense, net |  | $ | (5,039 | ) |  | $ | (4,137 | ) |  | $ | (902 | ) |  |  | 21.8 | % |  | $ | (14,872 | ) |  | $ | (11,420 | ) |  | $ | (3,452 | ) |  |  | 30.2 | %

Interest expense, net for the three and nine months ended September 30, 2025 increased compared to the three and nine months ended September 30, 2024 primarily as a result of higher interest rates and higher debt balances. Interest expense in the nine months ended September 30, 2025 was also impacted by the write off of deferred debt issuance costs of $0.9 million as a result of the refinancing of our senior secured credit facility in February 2025.

Weighted average interest rates, after giving effect to the impact of the interest rate swaps, as of September 30, 2025 and September 30, 2024 were 5.5% and 2.8%, respectively. See “—Key Factors that Affect Our Business and Our Results—Financing Costs” and Notes 12 and 13 to our unaudited condensed consolidated financial statements included in Part I, Item 1. “Financial Statements.”

Income Tax Expense

|  | Three Months Ended September 30, |  |  | Change |  |  | Nine Months Ended September 30, |  |  | Change |
(in thousands, except %) |  | 2025 |  |  | 2024 |  |  | $ |  |  | % |  |  | 2025 |  |  | 2024 |  |  | $ |  |  | % |
Income tax expense |  | $ | 7,281 |  |  | $ | 1,368 |  |  | $ | 5,913 |  |  |  | 432.2 | % |  | $ | 11,140 |  |  | $ | 4,480 |  |  | $ | 6,660 |  |  |  | 148.7 | %

The income tax expense for the three months ended September 30, 2025 increased compared to the three months ended September 30, 2024 primarily as a result of the continued utilization of tax attributes resulting in less indefinite-lived deferred tax assets available to offset the impact of indefinite-lived deferred tax liabilities.

The income tax expense for the nine months ended September 30, 2025 increased compared to the nine months ended September 30, 2024 primarily as a result of an overall increase in the net deferred tax liability recorded as of September 30, 2025 relative to September 30, 2024.

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Segment Results of Operations

The Three And Nine Months Ended September 30, 2025 Compared to the Three And Nine Months Ended September 30, 2024

|  | Three Months Ended September 30, |
|  | 2025 |  |  | 2024 |
(in thousands, except %) |  | Segment Revenues |  |  | Segment Adjusted EBITDA(1) |  |  | Segment Adjusted EBITDA Margin(2) |  |  | Segment Revenues |  |  | Segment Adjusted EBITDA(1) |  |  | Segment Adjusted EBITDA Margin(2) |
Assessment, Permitting and Response |  | $ | 91,081 |  |  | $ | 20,436 |  |  |  | 22.4 | % |  | $ | 52,019 |  |  | $ | 11,188 |  |  |  | 21.5 | %
Measurement and Analysis |  |  | 62,958 |  |  |  | 17,283 |  |  |  | 27.5 |  |  |  | 58,583 |  |  |  | 13,370 |  |  |  | 22.8 |
Remediation and Reuse |  |  | 70,849 |  |  |  | 9,412 |  |  |  | 13.3 |  |  |  | 68,085 |  |  |  | 11,655 |  |  |  | 17.1 |
Total Reportable Segments |  | $ | 224,888 |  |  | $ | 47,131 |  |  |  | 21.0 | % |  | $ | 178,687 |  |  | $ | 36,213 |  |  |  | 20.3 | %
Corporate and Other |  |  |  |  | $ | (13,470 | ) |  |  | (6.0 | )% |  |  |  |  | $ | (7,901 | ) |  |  | (4.4 | )%
|  | Nine Months Ended September 30, |
|  | 2025 |  |  | 2024 |
(in thousands, except %) |  | Segment Revenues |  |  | Segment Adjusted EBITDA(1) |  |  | Segment Adjusted EBITDA Margin(2) |  |  | Segment Revenues |  |  | Segment Adjusted EBITDA(1) |  |  | Segment Adjusted EBITDA Margin(2) |
Assessment, Permitting and Response |  | $ | 248,144 |  |  | $ | 58,563 |  |  |  | 23.6 | % |  | $ | 164,043 |  |  | $ | 40,088 |  |  |  | 24.4 | %
Measurement and Analysis |  |  | 184,783 |  |  |  | 49,354 |  |  |  | 26.7 |  |  |  | 158,889 |  |  |  | 32,233 |  |  |  | 20.3 |
Remediation and Reuse |  |  | 204,338 |  |  |  | 25,369 |  |  |  | 12.4 |  |  |  | 184,405 |  |  |  | 25,594 |  |  |  | 13.9 |
Total Reportable Segments |  | $ | 637,265 |  |  | $ | 133,286 |  |  |  | 20.9 | % |  | $ | 507,337 |  |  | $ | 97,915 |  |  |  | 19.3 | %
Corporate and Other |  |  |  |  | $ | (41,010 | ) |  |  | (6.4 | )% |  |  |  |  | $ | (29,367 | ) |  |  | (5.8 | )%

(1)
For purposes of evaluating segment profit, the Company’s Chief Operating Decision Maker reviews Segment Adjusted EBITDA as a basis for making the decisions to allocate resources and assess performance. See Note 19 to our unaudited condensed consolidated financial statements included in Part I, Item 1. “Financial Statements.”
(2)
Represents Segment Adjusted EBITDA as a percentage of segment revenues.

Revenues

|  | Three Months Ended September 30, |  |  | Change |  |  | Nine Months Ended September 30, |  |  | Change |
(in thousands, except %) |  | 2025 |  |  | 2024 |  |  | $ |  |  | % |  |  | 2025 |  |  | 2024 |  |  | $ |  |  | % |
Assessment, Permitting and Response |  | $ | 91,081 |  |  | $ | 52,019 |  |  | $ | 39,062 |  |  |  | 75.1 | % |  | $ | 248,144 |  |  | $ | 164,043 |  |  | $ | 84,101 |  |  |  | 51.3 | %
Measurement and Analysis |  |  | 62,958 |  |  |  | 58,583 |  |  |  | 4,375 |  |  |  | 7.5 |  |  |  | 184,783 |  |  |  | 158,889 |  |  |  | 25,894 |  |  |  | 16.3 |
Remediation and Reuse |  |  | 70,849 |  |  |  | 68,085 |  |  |  | 2,764 |  |  |  | 4.1 |  |  |  | 204,338 |  |  |  | 184,405 |  |  |  | 19,933 |  |  |  | 10.8 |
Total Reportable Segments |  | $ | 224,888 |  |  | $ | 178,687 |  |  | $ | 46,201 |  |  |  | 25.9 | % |  | $ | 637,265 |  |  | $ | 507,337 |  |  | $ | 129,928 |  |  |  | 25.6 | %

Assessment, Permitting and Response segment revenues for the three and nine months ended September 30, 2025 increased compared to the three and nine months ended September 30, 2024 due to organic growth within our non-response consulting and advisory services of $39.6 million and $45.0 million, respectively, partially driven by remediation consulting work cross sold from an initial emergency response incident, an increase in revenues from environmental emergency responses of $33.3 million, and $5.8 million from acquisitions, both in the year-to-date period. Emergency response revenues were down $0.5 million year-over-year for the three months ended September 30, 2025.

Measurement and Analysis segment revenues for the three and nine months ended September 30, 2025 increased compared to the three and nine months ended September 30, 2024 as a result of strong organic growth of $2.6 million and $16.0 million, respectively, and additional revenue from acquisitions of $2.4 million and $11.6 million, respectively, partially offset by a decrease in revenue of $0.6 and $1.8 million, respectively, related to a lab sold in the fourth quarter of 2024.

Remediation and Reuse segment revenues for the three and nine months ended September 30, 2025 increased compared to the three and nine months ended September 30, 2024, as a result of organic growth of $2.8 million and $12.4 million, respectively, and additional revenue from acquisitions of $7.6 million in the year-to-date period. Organic growth was driven primarily by growth in our water treatment business, partially offset by lower revenues in our renewables business.

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Segment Adjusted EBITDA

|  | Three Months Ended September 30, |  |  | Change |  |  | Nine Months Ended September 30, |  |  | Change |
(in thousands, except %) |  | 2025 |  |  | 2024 |  |  | $ |  |  | Margin % |  |  | 2025 |  |  | 2024 |  |  | $ |  |  | Margin % |
Assessment, Permitting and Response |  | $ | 20,436 |  |  | $ | 11,188 |  |  | $ | 9,248 |  |  |  | 0.9 | % |  | $ | 58,563 |  |  | $ | 40,088 |  |  | $ | 18,475 |  |  |  | (0.8 | )%
Measurement and Analysis |  |  | 17,283 |  |  |  | 13,370 |  |  |  | 3,913 |  |  |  | 4.6 |  |  |  | 49,354 |  |  |  | 32,233 |  |  |  | 17,121 |  |  |  | 6.4 |
Remediation and Reuse |  |  | 9,412 |  |  |  | 11,655 |  |  |  | (2,243 | ) |  |  | (3.8 | ) |  |  | 25,369 |  |  |  | 25,594 |  |  |  | (225 | ) |  |  | (1.5 | )
Total Reportable Segments |  | $ | 47,131 |  |  | $ | 36,213 |  |  | $ | 10,918 |  |  |  | 0.7 | % |  | $ | 133,286 |  |  | $ | 97,915 |  |  | $ | 35,371 |  |  |  | 1.6 | %
Corporate and Other |  | $ | (13,470 | ) |  | $ | (7,901 | ) |  | $ | (5,569 | ) |  |  |  |  | $ | (41,010 | ) |  | $ | (29,367 | ) |  | $ | (11,643 | ) |  |  |

Assessment, Permitting and Response Segment Adjusted EBITDA for the three and nine months ended September 30, 2025 increased compared to the three and nine months ended September 30, 2024 primarily as a result of higher revenues. Segment Adjusted EBITDA margin increased for the three months ended September 30, 2025 due to project mix, and decreased for the nine months ended September 30, 2025 as a result of higher bad debt expense, partially offset by favorable emergency response revenue, when compared to the prior year period.

Measurement and Analysis Segment Adjusted EBITDA for the three and nine months ended September 30, 2025 increased compared to the three and nine months ended September 30, 2024 as a result of higher revenues driven by organic growth. Segment Adjusted EBITDA margin for the three and nine months ended September 30, 2025 increased compared to the three and nine months ended September 30, 2024 as a result of improved operating performance and operating leverage.

Remediation and Reuse Segment Adjusted EBITDA for the three and nine months ended September 30, 2025 decreased compared to the three and nine months ended September 30, 2024 due primarily to losses incurred in our renewables business in the current year, partially offset by higher revenues in our water treatment business. Segment Adjusted EBITDA margin decreased as a result of losses incurred in our renewables business. Adjusted EBITDA in this business declined $1.5 million and $5.0 million in the three and nine months ended September 30, 2025, respectively. We anticipate that this business line will be fully wound down by December 31, 2025.

Corporate and other costs for the three and nine months ended September 30, 2025 when compared to the three and nine months ended September 30, 2024 increased primarily due to higher bonus accrual of $1.7 million and $7.5 million, respectively, driven in part by an outperformance in the current year versus the prior year, as well as higher outside service costs of $1.1 million and $2.4 million, respectively, related to an IT migration, and higher marketing expenses in the current year.

Liquidity and Capital Resources

Liquidity describes the ability of a company to generate sufficient cash flows to meet the cash requirements of its business operations, including working capital needs, debt service, acquisitions, other commitments and contractual obligations. We consider liquidity in terms of cash flows from operations and other sources, including availability under our senior secured credit facility, and their sufficiency to fund our operating and investing activities.

Our principal sources of liquidity have been borrowings under our senior secured credit facilities, other borrowing arrangements, proceeds from the issuance of common and preferred stock and cash generated by operating activities. Historically, we have financed our operations and acquisitions from a combination of cash generated from operations, periodic borrowings under senior secured credit facilities, and proceeds from the issuance of common and preferred stock. Our primary cash needs are for day to day operations, to fund working capital requirements, to fund our acquisition strategy and any related cash earn-out obligations, to pay interest and principal on our indebtedness and to make capital expenditures. Historically, our cash needs also included the payment of dividends on our Series A-2 preferred stock. Additionally, in connection with certain acquisitions, we agree to earn-out provisions and other purchase price adjustments that may require future payments. We may make up to $23.4 million in aggregate earn-out payments between the years 2025 and 2027 in connection with the acquisitions of Sensible, Epic, Spirit and Origins, of which up to $10.4 million may be paid only in cash, up to $2.8 million may be paid only in common stock and up to $10.2 million may be paid in cash or, at our option, in common stock. See Note 7 to our unaudited condensed consolidated financial statements included in Part 1, Item 1. “Financial Statements.” As of September 30, 2025, we had $191.7 million available under the 2025 Credit Facility (after giving effect to any outstanding letters of credit, and subject to borrowing base limitations), and $6.7 million of cash on hand. In April and July 2025, we redeemed the remaining $122.2 million in aggregate stated value of the outstanding Series A-2 preferred stock using cash and borrowings under our revolving line of credit.

We expect to continue to fund our liquidity requirements, including any cash earn-out payments that may be required in connection with acquisitions, through cash generated from operations and borrowings under our 2025 Credit Facility. We believe these sources will be sufficient to fund our cash needs for the short- and long-term.

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Cash Flows

The following table summarizes our cash flows for the periods presented:

|  | Nine Months Ended September 30, |
(in thousands) |  | 2025 |  |  | 2024 |
Net cash provided by (used in): |  |  |  |  |  |
Operating activities |  | $ | 55,548 |  |  | $ | (9,721 | )
Investing activities |  |  | (12,604 | ) |  |  | (137,190 | )
Financing activities |  |  | (49,242 | ) |  |  | 136,583 |
Change in cash, cash equivalents and restricted cash |  | $ | (6,298 | ) |  | $ | (10,328 | )

Operating Activities

Cash flows from operating activities can fluctuate from period-to-period as earnings, working capital needs and the timing of payments for contingent consideration, taxes, bonus payments and other operating items impact reported cash flows.

For the nine months ended September 30, 2025, net cash provided by operating activities was $55.5 million compared to net cash used in operating activities of $9.7 million for the nine months ended September 30, 2024. The period-over-period increase of $65.3 million was primarily due to an increase in cash earnings before non-cash items of $41.5 million, and improved working capital performance, reflecting a $44.4 million lower cash outflow.

Working capital (which excludes contingent consideration payments and changes in right-of-use assets) increased by $12.8 million in the nine months ended September 30, 2025, primarily due to a seasonal increase in accounts receivable of $28.8 million, partially offset by a $12.1 million increase in accrued payroll.

Working capital increased by $57.2 million in the nine months ended September 30, 2024, primarily due to an increase in accounts receivable of $45.9 million and a $4.9 million decrease in accrued payroll.

Investing Activities

For the nine months ended September 30, 2025, net cash used in investing activities was $12.6 million, driven by cash paid for the purchases of property and equipment of $10.9 million and $1.8 million in proprietary software development costs.

For the nine months ended September 30, 2024, net cash used in investing activities was $137.2 million, driven by cash paid for the acquisitions of Epic, 2DOT, ETA, Paragon, Spirit, and Origins, net of cash acquired of $113.0 million, $19.1 million in purchases of property and equipment, $3.4 million in payment of other purchase price obligations, and $2.1 million in proprietary software development costs.

Financing Activities

For the nine months ended September 30, 2025, net cash used in financing activities was $49.2 million. Cash used in financing activities was driven by repayments of borrowing of $495.6 million, redemption of the Series A-2 preferred stock of $122.2 million, a payment for contingent consideration of $5.5 million, repayments of finance leases of $8.9 million, dividends on the Series A-2 preferred stock of $4.2 million, and payment of financing cost of $2.0 million, partially offset by borrowing under our credit facility of $586.4 million.

For the nine months ended September 30, 2024, net cash provided by financing activities was $136.6 million. Cash provided by financing activities was driven by net proceeds from the issuance of common stock through a public offering of $121.8 million, net borrowing of $87.0 million, and proceeds from the exercise of stock options of $2.0 million, partially offset by a partial redemption of the Series A-2 preferred stock of $60.0 million, dividends on the Series A-2 preferred stock of $8.3 million, and repayments of finance leases of $4.4 million.

Credit Facilities

See Note 12 to our unaudited condensed consolidated financial statements included in Part I, Item 1. “Financial Statements.”

Series A-2 Preferred Stock

On July 1, 2025, we redeemed the remaining $62.2 million in aggregate stated value of the outstanding Series A-2 preferred stock. See Notes 15 and 22 to our unaudited condensed consolidated financial statements included in Part I, Item 1. “Financial Statements.”

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Stock Repurchase Program

On May 7, 2025, the Company announced that its Board of Directors has approved a stock repurchase program of up to $40.0 million. The repurchase program does not have a set expiration date. The Company did not make any stock repurchases in the three and nine months ended September 30, 2025.

Critical Accounting Policies and Estimates

Our 2024 Form 10-K includes a summary of the critical accounting policies and estimates we believe are the most important to aid in understanding our financial results. There have been no material changes to those critical accounting policies and estimates as disclosed therein, other than as described in Note 2 to our unaudited condensed consolidated financial statements included in Part I, Item 1. “Financial Statements.”

Item 3. Quantitative and Qualitati ve Disclosures About Market Risk.

Interest Rate Risk

We have market risk exposure arising from changes in interest rates on our credit facility, which bears interest at rates that are benchmarked subject to the Company’s leverage ratio and SOFR. Based on our overall interest rate exposure to variable rate debt outstanding as of September 30, 2025, which factors in our interest rate swaps on $200.0 million of debt, a 1.0% increase or decrease in interest rates on the term loan, aircraft loan, and revolving line of credit would impact our annual income (loss) before income taxes by approximately $1.2 million.

Inflation Risk

We experienced higher labor and significantly higher travel and other direct costs in the fiscal years ended December 31, 2023 and December 31, 2024 as a result of inflation, particularly in our Measurement and Analysis and Remediation and Reuse segments. In the nine months ended September 30, 2025, we also experienced, and continue to experience, higher labor costs as a result of inflation. We believe we have successfully raised prices in businesses with short term contracts to offset these inflationary effects. We also have and are continuing to raise prices on medium term (one to four quarter) contracts as these contracts are renewed or new contracts are won, and as a result have been able to offset much of the impact of inflation to date. We expect to continue to raise prices if direct costs continue to increase, and although inflation has increased our Selling, general and administrative expense in the nine months ended September 30, 2025, we do not believe over a longer period of time that inflation will have a material effect on our business, financial condition or results of operations. If our costs were to become subject to additional and unanticipated significant sustained inflationary pressures, we may not be able to fully offset such higher costs through price increases. Our inability or failure to do so could adversely affect our business, financial condition and results of operations.

Foreign Exchange Risk

Foreign exchange risk exposure arises because we conduct a portion of our business in currencies not denominated in U.S. dollars, most notably in, Canada, Australia and Europe. Our exposure to this risk has increased significantly due to our acquisitions of Paragon and Matrix in Canada, EPIC in Australia, and to a lesser extent, Vandrensning in Europe. As such, our future operating results are exposed to changes in exchange rates. When the U.S. dollar weakens against foreign currencies, the dollar value of revenues denominated in foreign currencies increases. When the U.S. dollar strengthens, the opposite situation occurs. Additionally, the translation of certain foreign denominated assets and liabilities into U.S. dollars, and the collection or payment of previously recognized assets and liabilities can be positively or negatively affected by changes in exchange rates. A 1.0% increase or decrease in the U.S. dollar exchange rate would impact revenues by approximately $1.5 million and would have a negligible impact on annual net (loss) income.

Item 4. Controls and Procedures.

Evaluation of Disclosure Controls and Procedures

As required by Rule 13a-15(b) under the Exchange Act, our management, including our Chief Executive Officer and Chief Financial Officer, carried out an evaluation of the effectiveness of the design and operation of our disclosure controls and procedures (as defined in Rule 13a-15(e) under the Exchange Act), as of September 30, 2025, the end of the period covered by this Quarterly Report on Form 10-Q. Based on the foregoing, our Chief Executive Officer and Chief Financial Officer concluded that, as of September 30, 2025, the end of the period covered by this Quarterly Report on Form 10-Q, our disclosure controls and procedures were effective at the reasonable assurance level.

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Internal Control Over Financial Reporting

There were no changes in our internal control over financial reporting (as defined in Rule 13a-15(f) under the Exchange Act) that occurred during the quarter ended September 30, 2025, that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

Limitations on Effectiveness of Controls

Our management, including our Chief Executive Officer and Chief Financial Officer, does not expect that our disclosure controls and procedures or our system of internal control over financial reporting will prevent or detect all errors and all fraud. A control system, no matter how well designed or operated, can provide only reasonable, but not absolute, assurance that the objectives of the system of internal control are met. The design of our control system reflects the fact that there are resource constraints, and that the benefits of such control system must be considered relative to their costs. Further, because of the inherent limitations in all control systems, no evaluation of controls can provide absolute assurance that all control failures and instances of fraud, if any, within the Company have been detected. These inherent limitations include the realities that judgments in decision-making can be faulty and that breakdowns can occur because of simple error or mistake. Additionally, controls can be circumvented by the intentional acts of individuals, by collusion of two or more people, or by management override of the controls. The design of any system of controls is also based in part on certain assumptions about the likelihood of future events, and there can be no assurance that the design of any particular control will always succeed in achieving its objective under all potential future conditions.

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PART II—OTHE R INFORMATION

Item 1. Legal Proceedings.

From time to time, we are subject to various legal proceedings that arise in the normal course of our business activities, including those involving labor and employment, anti-discrimination, commercial disputes and other matters. We are not a party to any litigation the outcome of which, if determined adversely to us, would individually or in the aggregate be reasonably expected to have a material adverse effect on our results of operations or financial position. Regardless of outcome, litigation can have an adverse impact on us because of defense and settlement costs, diversion of management resources and other factors.

Item 1A. Ri sk Factors.

There have been no material changes to our risk factors from the risk factors disclosed in our 2024 Form 10-K, as supplemented by the Q1 2025 Form 10-Q. The risks described in those filings, in addition to the other information set forth in this Quarterly Report on Form 10-Q, are not the only risks we face. Additional risks and uncertainties not currently known to us or that we currently deem to be immaterial also may materially adversely affect our business, financial condition and/or operating results.

Item 2. Unregistered Sales of Equi ty Securities and Use of Proceeds.

None.

Item 3. Defaults Upo n Senior Securities.

None.

Item 4. Mine Safe ty Disclosures.

Not applicable.

Item 5. Other Information.

On August 11, 2025, Allan Dicks, Chief Financial Officer, adopted a trading plan intended to satisfy Rule 10b5-1(c). The plan provides for the sale of up to 89,142 shares of Company common stock, up to 62,500 of which shares are to be acquired pursuant to the exercise of stock options, between November 13, 2025 and May 12, 2026, subject to certain conditions.

On August 11, 2025, Nasym Afsari, General Counsel, adopted a trading plan intended to satisfy Rule 10b5-1(c). The plan provides for the sale of up to 40,027 shares of Company Common Stock between November 13, 2025 and May 8, 2026, subject to certain conditions.

On August 12, 2025, Vijay Manthripragada, Chief Executive Officer, adopted a trading plan intended to satisfy Rule 10b5-1(c). The plan provides for the purchase of up to 234,125 shares of Company common stock, 209,125 of which shares are to be acquired pursuant to the exercise of stock options, and the sale of 134,950 shares plus an additional number of shares acquired pursuant to the exercise of stock options to fulfill the exercise price of 74,175 of such stock options between November 10, 2025 and August 12, 2026, subject to certain conditions.

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Item 6. E xhibits.

Exhibit Number |  | Description
31.1* |  | Certification of Principal Executive Officer Pursuant to Rules 13a-14(a) and 15d-14(a) under the Securities Exchange Act of 1934, as Adopted Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.
31.2* |  | Certification of Principal Financial Officer Pursuant to Rules 13a-14(a) and 15d-14(a) under the Securities Exchange Act of 1934, as Adopted Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.
32.1** |  | Certification of Principal Executive Officer Pursuant to 18 U.S.C. Section 1350, as Adopted Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.
32.2** |  | Certification of Principal Financial Officer Pursuant to 18 U.S.C. Section 1350, as Adopted Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.
101.INS* |  | Inline XBRL Instance Document
101.SCH* |  | Inline XBRL Taxonomy Extension Schema Document
104* |  | Cover Page Interactive Data File – The cover page from the Company’s Quarterly Report on Form 10-Q for the quarter ended September 30, 2025 is formatted in Inline XBRL (included as Exhibit 101)

* Filed herewith.

** Exhibit is furnished and shall not be deemed “filed” for purposes of Section 18 of the Exchange Act, or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act, or the Exchange Act, except as shall be expressly set forth by specific reference in such filing.

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SIGNA TURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

|  | Montrose Environmental Group, Inc.
Date: November 5, 2025 |  | By: | /s/ Allan Dicks
|  |  | Allan Dicks
|  |  | Chief Financial Officer

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