Onterris, Inc.

(In thousands, except where otherwise indicated)

1. DESCRIPTION OF THE BUSINESS AND BASIS OF PRESENTATION

Description of the Business

Onterris, Inc. (“Onterris” or the “Company”), formerly known as Montrose Environmental Group, Inc., is a corporation formed in November 2013, under the laws of the State of Delaware. The Company changed its name to Onterris on April 17, 2026. The Company has approximately 120 offices across the United States, Canada, and Australia and approximately 3,500 employees as of March 31, 2026.

Onterris 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. Historically, the Company hadthree reportable segments: Assessment, Permitting and Response, Measurement and Analysis, and Remediation and Reuse. Effective in the first quarter of 2026, the Company realigned its reportable segments to reflect updates made to its organizational structure and operating model. As a result of these changes, the Company aggregated the Assessment, Permitting and Response and Remediation and Reuse segments into a newly created Consulting and Treatment segment based on their similar characteristics, including similar long-term financial performance, the nature of services provided, internal processes for delivering those services, and types of customers. The Company's Measurement and Analysis and corporate segments were not affected by the realignment. See Note 19 – Segment Information for more details.

Consulting and Treatment segment provides environmental consulting, engineering, and implementation services to help clients assess, manage, and mitigate environmental risks across the lifecycle of their operations and projects. The Company supports environmental assessments, regulatory permitting, toxicology consulting, emergency preparedness, and response and environmental audits and permits, while also delivering engineering, design, and implementation solutions to treat contaminated water and remediate soil. The Company works closely with clients to navigate regulatory requirements, address environmental liabilities, respond to operational disruptions, and develop practical, sustainable solutions for new industrial developments, facility upgrades and ongoing operations. The Company provides these services as a consultant and service provider and does not own the properties, facilities, or underlying environmental liabilities associated with client projects.

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.

Corporate activities not directly related to segment performance, including general corporate expenses, interest and taxes, are reported separately.

Prior period information has been recast herein to reflect the above change in segment reporting. The recast segment information constitutes a reclassification and has no impact on reported net income (loss) or earnings (loss) per share for preceding periods. This change does not restate information previously reported in the consolidated statements of financial position, the consolidated statements of operations and comprehensive income (loss), consolidated statements of convertible and redeemable series A-2 preferred stock and stockholders’ equity or consolidated statements of cash flows for the Company for preceding periods.

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, 2025. 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.

Certain prior period amounts, which are not material, have been reclassified to conform to current period presentation in the notes to the condensed consolidated financial statements. The realigned segment information does not modify or update the disclosures included in the Company's Annual Report on Form 10-K for the year ended December 31, 2025 in any way, nor does it reflect any subsequent information or events, other than as required to reflect the change in segments as described above.

2. SUMMARY OF NEW ACCOUNTING PRONOUNCEMENTS

Recently Adopted Accounting Pronouncements

ASU 2025-05 —In July 2025, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU)2025-05, Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Assets (ASU 2025-05), which introduced a practical expedient when estimating expected credit losses for current accounts receivable and current contract assets arising from transactions accounted for under Topic 606. ASU 2025-05 is effective for the Company's fiscal years beginning after December 15, 2025, and interim periods within those fiscal years. The Company adopted the standard and elected the practical expedient on January 1, 2026. The adoption of the standarddid not have a material impact on the Company's consolidated financial statements.

Recently Issued Accounting Pronouncements Not Yet Adopted

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:

Consulting and Treatment Revenues are generated from multidisciplinary environmental consulting services, and engineering, design, implementation and operating and maintenance (O&M) services primarily to treat contaminated water and remove contaminants from soil. 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.

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, and 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 generally arise when billing occurs subsequent to revenue recognition, for example for services the Company is not contractually entitled to bill based on the passage of time. The Company sometimes receives advances or deposits from customers before revenue is recognized, resulting in contract liabilities.

The following table presents the Company’s contract balances:

Revenue recognized during the three months ended March 31, 2026, included in the contract liabilities balance at the beginning of the year was $5.7 million. 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 cost to cost 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 March 31, 2026 and December 31, 2025, the estimated revenue expected to be recognized in the future related to performance obligations that are unsatisfied was approximately $49.7 million and $68.4 million, respectively. As of March 31, 2026, the Company expected to recognize approximately $40.2 million of this amount as revenue within one year and $9.5 million theyear after.

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

The Company hadno customers that exceeded 10.0% of its gross receivables as of March 31, 2026 andone as of December 31, 2025. For the three months ended March 31, 2026, the Company hadone customer who accounted for more than 10.0% of revenue. For thethree months ended March 31, 2025 the Company hadno customers who accounted for more than 10.0% 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, the Company 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 the Company's senior secured credit facility. The Company has no retained interests in the sold receivables and only performs collection and administrative functions for the purchaser. The Company accounts for these receivable transfers as sales under ASC 860, Transfers and Servicing. During the three months ended March 31, 2026 and 2025 the Company did not sell any accounts receivable.

The allowance for credit losses consisted of the following:

4. PREPAID AND OTHER CURRENT ASSETS

Prepaid and other current assets consisted of the following:

5. PROPERTY AND EQUIPMENT, NET

Property and equipment, net, consisted of the following:

Total depreciation expense included in the unaudited condensed consolidated statements of operations was $3.4 million for the three months ended March 31, 2026 and $3.2 million for the three months ended March 31, 2025.

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.

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—The Company has an equipment line of credit, specifically dedicated for the purchases of allowable equipment and related freight, installation costs and taxes paid. As of March 31, 2026, the outstanding balance was $15.0 million on this credit line. Interest on leases financed under this facility is fixed and based on the SOFR swap rate on or closest to the closing date. As of March 31, 2026 equipment leased through this line of credit met the finance lease criteria as per ASC 842 and accordingly is accounted for as finance lease ROU assets and finance lease liabilities.

The components of lease expense were as follows:

Supplemental cash flows information related to leases was as follows:

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

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

7. BUSINESS ACQUISITIONS

During the three months ended March 31, 2026 and 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 $9.6 million in aggregate earn-out payments between the years 2026 and 2027 in connection with certain of its business acquisitions, of which up to $5.1 million may be paid only in cash, up to $2.8 million may be paid only in common stock and up to $1.7 million may be paid, at the Company’s option, in cash or common stock.

Transaction costs related to previous business combinations totaled $0.1 million for the three months ended March 31, 2026 and $0.7 million for the three months ended March 31, 2025. These costs are expensed within selling, general and administrative expense in the accompanying unaudited condensed consolidated statements of operations.

8. GOODWILL AND INTANGIBLE ASSETS

The Company tests each of its reporting units for goodwill impairment annually on October 1, or upon a triggering event, in accordance with ASC Topic 350, “Intangibles –Goodwill and Other.” Effective in the first quarter of 2026, the Company reorganized its business intotwo reportable segments as discussed in Note 19 – Segment Information. This changed the composition of the Company's reporting units which resulted in the combination of historical goodwill from the Assessment, Permitting and Response and Remediation and Reuse segments to its newly created Consulting and Treatment segment. Additionally, the change in composition of the Company's reporting units was considered a triggering event requiring an interim goodwill impairment test as of March 31, 2026. The Company determined that no impairment existed as the estimated fair values of its reporting units were in excess of their respective carrying values, both before and after the reorganization. Amounts related to goodwill are as follows:

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

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 $6.7 million three months ended March 31, 2026 and $8.4 million for the three months ended March 31, 2025.

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

9. ACCOUNTS PAYABLE AND OTHER ACCRUED LIABILITIES

Accounts payable and other accrued liabilities consisted of the following:

10. ACCRUED PAYROLL AND BENEFITS

Accrued payroll and benefits consisted of the following:

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(22.2)% for the three months ended March 31, 2026 and(17.4)% for the three months ended March 31, 2025. Income tax expense recorded by the Company during the three months ended March 31, 2026 and 2025 was $2.3 million and $2.9 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 March 31, 2026, 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. As of March 31, 2026, the Company had uncertain tax positions of $0.6 million. 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.

12. DEBT

Debt consisted of the following:

Deferred Financing Costs—Costs relating to debt issuance have been deferred and are presented as netted against the underlying debt balance. These costs are amortized to interest expense over the terms of the underlying debt instruments. The amortization of deferred debt issuance cost to interest expense was $0.1 million and $1.1 million for the three months ended March 31, 2026 and 2025, respectively.

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). 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 Company used proceeds from the 2025 Credit Facility to repay in full its prior senior secured credit facility originally entered into in 2021. The resulting write-off of the remaining unamortized debt issuance costs from the prior credit facility amounted to $0.9 million. Total loss on debt extinguishments was recorded in interest expense, net within the consolidated statements of operations for the three months ended March 31, 2025.

The 2025 Credit Facility term loan must be repaid in quarterly installments and amortizes 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 benchmark spread as follows:

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 through 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 commenced in the fourth quarter of 2025. For thethree months ended March 31, 2026, quarterly term loan installment repayments under the 2025 Credit Facility were $2.5 million.

As of March 31, 2026 and December 31, 2025, the Company’s consolidated total leverage ratio (as defined in the 2025 Credit Facility) was 2.8 times and 2.5 times, respe ctively, and the Company was in compliance with all covenants under the 2025 Credit Facility.

The 2025 Credit Facility requires customary mandatory prepayments of the term loan and revolving line of credit 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 for the three months ended March 31, 2026, before giving effect to the impact of the interest rate swaps, was 5.7% and after giving effect to the impact of the interest rate swaps, was 5.6%. The weighted average interest rate for the three months ended March 31, 2025, before giving effect to the impact of the interest rate swaps, was 6.3% and after giving effect to the impact of the interest rate swaps, was 5.5%.

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 March 31, 2026, the Company had the following interest rate swap agreements in place:

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 spread 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.

The 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 March 31, 2026, before deferred debt issuance cost of $1.9 million, based on the terms of the 2025 Credit Facility and the Aircraft Loan:

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):

(1)Included in prepaid and other current assets and other non-current liabilities in the unaudited condensed consolidated statement of financial position as of March 31, 2026 and audited condensed consolidated statement of financial position as of December 31, 2025, respectively.

(2)Included in prepaid and other current assets in the unaudited condensed consolidated statement of financial position as of March 31, 2026.

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:

14. COMMITMENTS AND CONTINGENCIES

Leases—The Company leases office facilities over various terms expiring through 2040. Certain of these operating leases contain rent escalation clauses. The Company also has office equipment leases that expire through 2045 (Note 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 $0.4 million and $0.9 million for 2026 and 2027, respectively, with the remainder subject to mutual agreement after 2027. No purchases were made during thethree months ended March 31, 2026 and 2025.

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, any 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. 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 Convertible and Redeemable Series A-2 Preferred Stock had a dividend rate of 9.0% per year with required quarterly cash payments. 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 were paid in cash. The Company paid dividends on shares of the Convertible and Redeemable Series A-2 Preferred Stock of $2.8 million during the three months ended March 31, 2025.

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. The change in net fair value of $0.3 million for thethree months ended March 31, 2025 was recorded to other (income) expense.

16. STOCKHOLDERS’ EQUITY

Stock Repurchase Program

On May 6, 2025, the Board of Directors approved a stock repurchase program of up to $40.0 million. The repurchase program does not have a set expiration date. During thethree months ended March 31, 2026, the Company repurchased 376,313 shares of its common stock for approximately $10.0 million, inclusive of transaction fees. Repurchased shares are accounted for as treasury stock and are presented as a deduction from total equity in the Company's unaudited condensed consolidated statements of convertible and redeemable series A-2 preferred stock and stockholders’ equity. As of March 31, 2026, approximately $30.0 million of the authorized capacity under the repurchase program remained available for future repurchases.

Employee Equity Incentive Plans

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

(1) In January 2026 and January 2025 the Board of Directors ratified the addition of 1,436,436 and 1,372,373 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.

17. NET LOSS PER SHARE

Basic net 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 was considered a participating security during the prior year period. Net losses were 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 loss per share is computed by dividing net 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), and shares of common stock underlying stock options outstanding under the Company's stock incentive plans, as applicable. During the three months ended March 31, 2026 and 2025 there was 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.

The following table summarizes the computation of basic and dilutednet loss per share attributable to common stockholders of the Company:

The following common stock equivalents were excluded from the calculation of diluted net loss per share attributable to common stockholders for the three months ended March 31, 2026 and the three months ended March 31, 2025 because their effect would have been anti-dilutive:

(1)Includes 1,990,423 and 2,411,688 common stock equivalents that are out of the money as of March 31, 2026 and March 31, 2025, respectively.

18. STOCK-BASED PLANS AND COMPENSATION

There wereno stock-based compensation expenses related to the 2013 Plan in thethree months ended March 31, 2026 and 2025. Total stock-based compensation expense related to the 2017 Plan was as follows:

As of March 31, 2026 and March 31, 2025, there was $54.0 million and $76.7 million, respectively, of total unrecognized stock-based compensation expense related to unvested options and restricted stock under the 2017 Plan. Such unrecognized expense is expected to be recognized over a weighted-average 2.1 year period.

Amended & Restated 2017 Stock Incentive Plan

Restricted Stock Awards and Restricted Stock Units

RSAs and RSUs activity was as follows:

Options

The following summarizes the options activity of the 2017 Plan:

Amended & Restated 2013 Stock Option Plan

The following summarizes the activity of the 2013 Plan:

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:

(1)In January 2026 and 2025, the Board of Directors ratified the addition of 1,436,436 and 1,372,373 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 tosettle 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.

19. SEGMENT INFORMATION

Histori cally, the Company hadsix operating units that aggregate into three reportable segments: Assessment, Permitting and Response, Measurement and Analysis, and Remediation and Reuse. Effective in the first quarter of 2026, the Company realigned its reportable segments to reflect changes in its organizational structure and operating model. As a result of these changes, the Company now managestwo reportable segments, namely Consulting and Treatment and Measurement and Analysis. Specifically, the Assessment, Permitting and Response segment and Remediation and Reuse segment were aggregated into the new Consulting and Treatment segment based on their similar characteristics, including similar long-term financial performance, the nature of services provided, internal processes for delivering those services, and types of customers. The Company's Measurement and Analysis and corporate segments were not affected by the realignment.

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.

The Company's 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. Effective in the first quarter of 2026, the Company updated its reportable segments to reflect changes in its organizational structure and internal reporting described above. Accordingly, the Company’s updated segments represent the components whose operating results are regularly reviewed by the CODM to make decisions about the allocation of resources and to assess 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.

The following table presents Segment Revenues, Segment Expenses and Segment Adjusted EBITDA, with prior period information recast to reflect the above change in segment reporting:

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

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

(2)Thethree months ended March 31, 2026 consist primarily of the change in fair value of the interest rate swap instruments. The three months ended March 31, 2025 consist primarily of the change in fair value of the interest rate swap instruments and the embedded derivative attached to the Series A-2 preferred stock.

(3)Thethree months ended March 31, 2026 consist primarily of IT migration costs. The three months ended March 31, 2025 consist primarily of 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 following table presents revenues by geographic location:

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

20. RELATED-PARTY TRANSACTIONS

The Company didnot have any material related party transactions during the three months ended March 31, 2026 and 2025.

21. DEFINED CONTRIBUTION PLAN

On January 1, 2014, the Company established the Company's 401(k) Savings Plan (the 401(k) Savings Plan). As of March 31, 2026, and December 31, 2025, 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 $3.6 million for the three months ended March 31, 2026 and $2.8 million for the three months ended March 31, 2025.

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;

•

our ability to adapt to changing technology, industry standards or regulatory requirements, including emerging environmental, social and governance requirements;

•

the highly competitive nature of our business;

•

significant environmental governmental regulation or de-regulation;

•

our ability to execute on our acquisition strategy and successfully integrate and realize benefits from our acquisitions;

•

our ability to maintain and expand our client base;

•

our ability to attract and retain qualified managerial and skilled technical personnel;

•

safety-related issues;

•

any failure in or breach of our networks and systems or other forms of cyber-attack;

•

our ability to promote and develop our new brand;

•

our ability to maintain necessary accreditations and other authorizations in varying jurisdictions;

•

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;

•

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, 2025 filed with the SEC on February 26, 2026, or the 2025 Form 10-K.

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 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.