CASELLA WASTE SYSTEMS INC

Estimated minimum future lease obligations as of December 31, 2025 for each of the next five fiscal years and thereafter are as follows:

9. GOODWILL AND INTANGIBLE ASSETS

A summary of the activity and balances related to goodwill by reportable operating segment is as follows:

(1)December 31, 2023 and 2024 amounts, which include allocated goodwill between operating segments using a relative fair value approach, have been reclassified between regional operating segments to conform to the current period presentation. See Note 21, Segment Reporting for further disclosure.

A summary of intangible assets is as follows:

Intangible amortization expense for fiscal years 2025, 2024 and 2023 was $76,475, $56,481 and $31,037, respectively.

Based on the amortizable intangible assets recorded in the consolidated balance sheets at December 31, 2025, intangible amortization expense for each of the next five fiscal years and thereafter is estimated as follows:

10. ACCRUED FINAL CAPPING, CLOSURE AND POST-CLOSURE COSTS

Accrued final capping, closure and post-closure costs include the current and non-current portion of costs associated with obligations for final capping closure and post-closure of our landfills. We estimate our future final capping, closure and post-closure costs of our landfills in order to determine the final capping, closure and post-closure expense per ton of waste placed into each landfill as further described in Note 3, Summary of Significant Accounting Policies. The anticipated time frame for paying these costs varies based on the remaining useful life of each landfill, as well as the duration of the post-closure monitoring period.

The changes to accrued final capping, closure and post-closure liabilities are as follows:

(1)Relates to changes in estimates and assumptions concerning anticipated waste flow, costs, including as a result of higher inflation, and timing of future final capping, closure and post-closure activities at our landfills. Fiscal year 2024 includes $8,385 related to the revision in estimates of the post-closure liability for the Town of Southbridge, Massachusetts landfill (“Southbridge Landfill”), related to the final closure permit (“Closure Permit”). See Note 18, Other Items and Charges for further disclosure over the Southbridge Landfill revision.

(2)May include amounts paid and amounts that are being processed through accounts payable as a part of our disbursement cycle.

(3)Relates to the recovery in fiscal year 2024 of historical payments written off associated with capping work that was deemed no longer viable due to a veneer failure at the Ontario County Landfill, which we operate, that occurred in fiscal year 2023, after an engineering evaluation determined that a portion of the affected area was still viable. See Note 18, Other Items and Chargesfor additional disclosure.

11. OTHER CURRENT ASSETS

Other current assets, classified as current assets, at December 31, 2025 and 2024 are as follows:

12. DEBT

A summary of debt is as follows:

Credit Facility

In September 2024, we entered into a second amended and restated credit agreement (“Credit Agreement”), which amended and restated in its entirety our amended and restated credit agreement (“Prior Credit Agreement”). The Credit Agreement provides for an $800,000 aggregate principal amount Term Loan Facility and a $700,000 Revolving Credit Facility, with a $155,000 sublimit for letters of credit (collectively, the “Credit Facility”). A portion of the proceeds of the Credit Facility refinanced in full our term loans under the Prior Credit Agreement.

We have the right to request, at our discretion, an increase in the amount of loans under the Credit Facility by an aggregate amount of $200,000, subject to further increase based on the terms and conditions set forth in the Credit Agreement. The Credit Facility has a 5-year term that matures in September 2029. The Credit Facility shall bear interest, at our election, at Term SOFR or at a base rate, in each case plus or minus any sustainable rate adjustment of up to positive or negative 4.0 basis points per annum, plus an applicable interest rate margin based upon our consolidated net leverage ratio as follows:

A commitment fee will be charged on undrawn amounts of our Revolving Credit Facility based upon our consolidated net leverage ratio in the range of 0.200% to 0.400% per annum, plus a sustainability adjustment of up to positive or negative 1.0 basis point per annum. The Credit Agreement provides that Term SOFR is subject to azero percent floor. We are also required to pay a fronting fee for each letter of credit of 0.250% per annum. Interest under the Credit Agreement is subject to increase by 2.000% per annum during the continuance of a payment default and may be subject to increase by 2.000% per annum during the continuance of any other event of default. The Credit Facility is guaranteed jointly and severally, fully and unconditionally by all of our significant wholly-owned subsidiaries and secured by substantially all of our assets. As of December 31, 2025, further advances were available under the Credit Facility in the amount of $673,418. The available amount is net of outstanding irrevocable letters of credit totaling $26,582, and as of December 31, 2025 no amount had been drawn.

The Credit Agreement requires us to maintain a minimum interest coverage ratio and a maximum consolidated net leverage ratio, to be measured at the end of each fiscal quarter. In addition to these financial covenants, the Credit Agreement contains a number of important customary affirmative and negative covenants which restrict, among other things, our ability to sell assets, incur additional debt, create liens, make investments, and pay dividends. As of December 31, 2025, we were in compliance with the covenants contained in the Credit Agreement. An event of default under any of our debt agreements could permit some of our lenders, including the lenders under the Credit Facility, to declare all amounts borrowed from them to be immediately due and payable, together with accrued and unpaid interest, or, in the case of the Credit Facility, terminate the commitment to make further credit extensions thereunder, which could, in turn, trigger cross-defaults under other debt obligations. If we were unable to repay debt to our lenders or were otherwise in default under any provision governing our outstanding debt obligations, our secured lenders could proceed against us and against the collateral securing that debt.

Tax-Exempt Financings

Industrial revenue bonds are tax-exempt municipal debt securities issued by a government agency on our behalf and sold only to qualified institutional buyers. As of December 31, 2025, we had outstanding $273,500 aggregate principal amount of tax-exempt bonds issued by the states of New York, Vermont, Maine and New Hampshire (collectively, the “Industrial Revenue Bonds”), which are unsecured and guaranteed jointly and severally, fully and unconditionally by all of our significant wholly-owned subsidiaries, and require interest payments semi-annually. The Industrial Revenue Bonds have fixed rate interest periods. At the end of each respective fixed rate interest period, the corresponding tax-exempt bond may be converted to a variable rate interest period or remarketed over a new fixed rate interest period. We borrowed the proceeds of the Industrial Revenue Bonds to finance or reimburse certain qualified capital projects and other costs in each respective state of issuance as defined in the related offering memorandum and indenture.

In fiscal year 2025, we completed the following transactions: (i) the drawdown of $25,000 aggregate principal amount of Vermont Bonds 2022A-2, which bears a fixed interest rate of 4.375% through May 2032, (ii) the remarketing of $29,000 aggregate principal amount of FAME Bonds 2015R-1 and FAME Bonds 2015R-2 into a single series FAME Bonds 2015R-3, which bears a fixed interest rate of 5.000% through August 2035, and (iii) the remarketing of $37,500 aggregate principal amount of New York Bonds 2020, which bears an interest rate of 4.250% through September 2030.

In fiscal year 2024, we completed the issuance of $45,000 aggregate principal amount of FAME Bonds 2024, which bears a fixed interest rate of 4.625% through May 2035, and $25,000 of the proceeds of such issuance were used for the repayment in full of FAME Bonds 2005R-3, which matured and were repaid in January 2025.

Cash, Cash Equivalents and Restricted Cash

Restricted cash is included with restricted assets, as well as cash and cash equivalents in our consolidated balance sheets based on the nature of the underlying restrictions. Our restricted cash included with restricted assets, classified as non-current assets as of December 31, 2025, was associated with legally restricted cash held in an escrow account due to the timing of the close of the Mountain State Waste Acquisition. Our restricted cash included with cash and cash equivalents, classified as current assets as of December 31, 2024, consisted of cash proceeds from the issuance of the FAME Bonds 2024 restricted to be used for the repayment in full of FAME Bonds 2005R-3, classified as a current liability as of December 31, 2024, on its stated maturity in January 2025.

A reconciliation of cash, cash equivalents and restricted cash, including non-current, is as follows:

Interest Expense

The components of interest expense are as follows:

(1)Includes interest expense related to a short-term secured bridge financing entered into in connection with the GFL Acquisition and interest expense related to a short-term unsecured bridge financing entered into in connection with the Twin Bridges Acquisition of $395 and $101, respectively, during the fiscal year 2023.

Debt Modification Expense

In fiscal year 2024, we recognized debt modification expense of $1,396 associated with agent fees and other third-party costs we paid during the refinancing of the Credit Agreement.

Loss from Termination of Bridge Financing

In fiscal year 2023, we wrote-off the unamortized debt issuance costs and recognized a loss from termination of bridge financing upon the extinguishment of both a secured bridge financing agreement in connection with the GFL Acquisition of $3,718, and an unsecured bridge financing agreement in connection with the Twin Bridges Acquisition of $4,473.

Cash Flow Hedges

Our strategy to reduce exposure to interest rate risk involves entering into interest rate derivative agreements to hedge against adverse movements in interest rates related to the variable rate portion of our long-term debt. We have designated these derivative instruments as highly effective cash flow hedges, and therefore the change in their fair value is recorded in stockholders’ equity as a component of accumulated other comprehensive (loss) income, net of tax and included in interest expense at the same time as interest expense is affected by the hedged transactions. See Note 14, Stockholders’ Equity for further disclosure over the impact of cash flow hedges to accumulated other comprehensive (loss) income, net of tax. Differences paid or received over the life of the agreements are recorded as additions to or reductions of interest expense on the underlying debt and included in cash flows from operating activities.

A summary of the changes to the notional amount of interest rate derivative agreements follows:

As of both December 31, 2025 and December 31, 2024, our active interest rate derivative agreements had a total notional amount of $515,000. According to the terms of the agreements, we receive interest based on Term SOFR, restricted by a 0.0% floor, and pay interest at a weighted average rate of approximately 3.6%. These agreements mature or have matured between February 2026 and June 2028.

A summary of the effect of cash flow hedges related to derivative instruments on the consolidated balance sheets follows:

Fair Value of Debt

As of December 31, 2025, the fair value of the Industrial Revenue Bonds was approximately $275,334 and the carrying value was $273,500. The fair value of the Industrial Revenue Bonds is considered to be Level 2 within the fair value hierarchy as the fair value is determined using market approach pricing provided by a third party that utilizes pricing models and pricing systems, mathematical tools and judgment to determine the evaluated price for the security based on the market information of each of the bonds or securities with similar characteristics.

As of December 31, 2025, the carrying value of our Term Loan Facility was $800,000 and the carrying value of our Revolving Credit Facility waszero dollars. Their fair values are based on current borrowing rates for similar types of borrowing arrangements, or Level 2 inputs, and approximate their carrying values.

Although we have determined the estimated fair value amounts of the Industrial Revenue Bonds using available market information and commonly accepted valuation methodologies, a change in available market information, and/or the use of different assumptions and/or estimation methodologies could have a material effect on the estimated fair values. These amounts have not been revalued, and current estimates of fair value could differ significantly from the amounts presented.

Future Maturities of Debt

Aggregate principal maturities of debt as of December 31, 2025 for each of the next five fiscal years and thereafter are as follows:

13. COMMITMENTS AND CONTINGENCIES

In the ordinary course of our business and as a result of the extensive governmental regulation of the solid waste industry, we are subject to various judicial and administrative proceedings involving state and local agencies. In these proceedings, an agency may seek to impose fines or to revoke or deny renewal of an operating permit held by us. From time to time, we may also be subject to actions brought by special interest or other groups, adjacent landowners or residents in connection with the permitting and licensing of landfills and transfer stations, or allegations of environmental damage or violations of the permits and licenses pursuant to which we operate. In addition, we may be named defendants in various claims and suits pending for alleged damages to persons and property, alleged violations of certain laws and alleged liabilities arising out of matters occurring during the ordinary operation of a waste management business. The plaintiffs in some actions seek unspecified damages or injunctive relief, or both. These actions fall within various procedural stages at any point in time, and some are covered in part by insurance.

In accordance with FASB ASC 450 - Contingencies, we accrue for legal proceedings, inclusive of legal costs, when losses become probable and reasonably estimable. We have recorded an aggregate accrual, net of payments of $1,815 relating to our outstanding legal proceedings as of December 31, 2025, and it is at least reasonably possible that a change in estimate will occur in the near-term. As of the end of each applicable reporting period, we review each of our legal proceedings to determine whether it is probable, reasonably possible or remote that a liability has been incurred and, if it is at least reasonably possible, whether a range of loss can be reasonably estimated under the provisions of FASB ASC Subtopic 450-20. In instances where we determine that a loss is probable and we can reasonably estimate a range of loss we may incur with respect to such a matter, we record an accrual for the amount within the range that constitutes our best estimate of the possible loss. If we are able to reasonably estimate a range, but no amount within the range appears to be a better estimate than any other, we record an accrual in the amount that is the low end of such range. When a loss is reasonably possible, but not probable, we will not record an accrual, but we will disclose our estimate of the possible range of loss where such estimate can be made in accordance with FASB ASC 450-20. We disclose outstanding matters that we believe could have a material adverse effect on our financial condition, results of operations or cash flows. See Note 18, Other Items and Charges for disclosure regarding a legal settlement charge recorded in fiscal year 2023.

North Country Environmental Services Letter of Deficiency

On June 14, 2024, our subsidiary, North Country Environmental Services, Inc. (“NCES”), received a Letter of Deficiency (the “Letter”) from the New Hampshire Department of Environmental Services (“NHDES”) concerning alleged violations related to leachate management and leachate data and reporting. The Letter required certain actions to correct the deficiencies on a prescribed timeline, and NCES has met the deadlines for information submission. On January 12, 2026, the New Hampshire Department of Justice and NCES entered into a Consent Decree resolving the alleged violations and requiring the payment of a $1,900 civil penalty, part of which may be offset through approved Supplemental Environmental Projects focused on stabilizing landfill debris impacting the Saco River, of which one such project has already been implemented. The Consent Decree is subject to court approval. The terms of the settlement allow for us to receive a credit towards the penalty for field work costs associated with a Supplemental Environmental Project. The accrual has been reduced to account for these sums that have already been paid.

Granite State Landfill Solid Waste Permit Denial

On April 3, 2025, NHDES denied the October 31, 2023 application of our subsidiary, Granite State Landfill, LLC (“GSL”), for the development of new landfill capacity in New Hampshire. On April 8, 2025, GSL filed a Petition for Declaratory Judgment in the Merrimack Superior Court (“Court”) requesting that the Court find that NHDES’s denial of GSL’s application was unlawful (“Petition”). On May 9, 2025, NHDES filed an Answer to the Petition. On June 23, 2025, North Country Alliance for Balanced Change (“NCABC”) filed a Motion to Intervene, in response to which GSL filed an Objection on June 30, 2025. On July 1, 2025, a scheduling conference was held and the Court issued a Scheduling Order of the same date providing that the issues raised in the Petition appear to be a legal dispute that can be addressed by cross-motions for summary judgment, and requiring the parties to confer and submit briefing schedule proposals to the Court on or before July 18, 2025. A Joint Proposed Briefing Schedule was filed by the parties on July 17, 2025. NCABC filed a reply to GSL’s Objection to NCABC’s Motion to Intervene on July 25, 2025. On August 5, 2025, the Court issued an order granting NCABC’s Motion to Intervene. GSL timely moved for reconsideration of that order, which was denied on September 2, 2025. GSL then filed a Motion for an Interlocutory Appeal on September 12, 2025, to challenge NCABC’s standing to intervene. NCABC objected to the Motion for an Interlocutory Appeal on September 22, 2025. On September 15, 2025, GSL and NHDES filed cross-motions for summary judgment. NCABC joined in NHDES’s motion. GSL’s and NHDES’s objections to the cross-motions for summary judgment were submitted October 15, 2025. A hearing on the motions for summary judgment is currently scheduled for February 26, 2026.

On May 5, 2025, GSL and NCABC each filed a Notice of Appeal of NHDES’s denial of GSL’s application with the New Hampshire Waste Management Council (“GSL Appeal” and “NCABC Appeal”, respectively). On May 9, 2025, GSL filed a partially assented to Motion to Intervene in the NCABC Appeal, followed by a Motion to Dismiss the NCABC Appeal on June 27, 2025. NHDES filed a Motion to Dismiss the NCABC Appeal on July 17, 2025. NCABC filed an Objection to GSL’s

Motion to Dismiss on July 24, 2025 and to NHDES’s Motion to Dismiss on July 28, 2025. On August 8, 2025, NCABC filed a Motion to Intervene in the GSL Appeal which will depend on the success or failure of GSL’s Motion to Dismiss the NCABC Appeal. A hearing officer was assigned to these appeals on November 14, 2025. As of December 31, 2025, we had $13,511 of capitalized project development costs related to the GSL landfill project included in other non-current assets.

Juniper Ridge Landfill Public Benefit Determination Remand on Appeal

On January 7, 2026, the Penobscot Superior Court (“Superior Court”) issued a decision in the matter of Penobscot Nation & Conservation Law Foundation (“Petitioners”) v. Maine Department of Environmental Protection (“Department”), with Casella subsidiary, NEWSME Landfill Operations, LLC as Party‑in‑Interest, addressing the Petitioners’ challenge to the Department’s public benefit determination for the proposed expansion of the Subtitle D landfill located in West Old Town, Maine (“Juniper Ridge Landfill”) that we operate. The Superior Court granted Petitioners’ motion for judicial notice and found that the Department failed to make necessary factual findings regarding both the need for on‑site sludge‑drying and the cumulative environmental burdens borne by the Penobscot Nation. The Superior Court remanded the matter for the Department to make additional findings on these issues. The Department must issue a revised public benefit determination within 75 days, and the Superior Court retains jurisdiction during the remand.

Environmental Remediation Liabilities

We are subject to liability for environmental damage, including personal injury and property damage, that our solid waste, recycling and power generation facilities may cause to neighboring property owners, particularly as a result of the contamination of drinking water sources or soil, possibly including damage resulting from conditions that existed before we acquired the facilities. We may also be subject to liability for similar claims arising from off-site environmental contamination caused by pollutants or hazardous substances if we or our predecessors arrange or arranged to transport, treat or dispose of those materials.

We accrue for costs associated with environmental remediation obligations when such costs become both probable and reasonably estimable. Determining the method and ultimate cost of remediation requires that a number of assumptions be made. There can sometimes be a range of reasonable estimates of the costs associated with remediation of a site. In these cases, we use the amount within the range that constitutes our best estimate. In the early stages of the remediation process, particular components of the overall liability may not be reasonably estimable; in this instance we use the components of the liability that can be reasonably estimated as a surrogate for the liability. It is reasonably possible that we will need to adjust the liabilities recorded for remediation to reflect the effects of new or additional information, to the extent such information impacts the costs, timing or duration of the required actions, which could have a material adverse effect on our consolidated financial position, results of operations and cash flows. We disclose outstanding environmental remediation matters that remain unsettled or are settled in the reporting period that we believe could have a material adverse effect on our financial condition, results of operations or cash flows.

We inflate the estimated costs in current dollars to the expected time of payment and discount the total cost to present value using a risk-free interest rate when the amount and timing of cash payments for the liability are fixed or reliably determinable. The weighted-average risk-free interest rate associated with our environmental remediation liabilities as of December 31, 2025 was approximately 1.8%. A summary of the changes to the aggregate environmental remediation liabilities for the fiscal years ended December 31, 2025 and 2024 follows:

(1)Related to soil remediation at an organic residuals composting facility that we own in Maine as part of our activities associated with ceasing operations at the site. See Note 18, Other Items and Chargesfor further disclosure over the site closure and related organics facility closure charge.

(2)Associated with a revision in estimates related to the restoration of a stream bed on lands adjoining one of the landfills that we own.

(3)May include amounts paid and amounts that are being processed through accounts payable as a part of our disbursement cycle.

The total expected environmental remediation payments, as of December 31, 2025 for each of the next five fiscal years and thereafter are as follows:

A reconciliation of the expected aggregate non-inflated, undiscounted environmental remediation liabilities to the amount recognized in ourconsolidated balance sheet at December 31, 2025 is as follows:

Any substantial liability incurred by us arising from environmental damage could have a material adverse effect on our business, financial condition and results of operations.

14. STOCKHOLDERS' EQUITY

Public Offering of Class A Common Stock

In September 2024, we completed a public offering of 5,175 shares of our Class A common stock at a public offering price of $100.00 per share. After deducting stock issuance costs, including underwriting discounts, commissions and offering expenses, the offering resulted in net proceeds of $496,245. The net proceeds from this offering were and are to be used to repay borrowings under our Revolving Credit Facility and are further available to fund acquisition activity and for general corporate purposes.

In June 2023, we completed a public offering of 6,053 shares of our Class A common stock at a public offering price of $85.50 per share. After deducting stock issuance costs, including underwriting discounts, commissions and offering expenses, the offering resulted in net proceeds of $496,231. The net proceeds from this offering were and are to be used to fund acquisition activity, including the GFL Acquisition and the Twin Bridges Acquisition, to pay certain costs associated with acquisition activities, as discussed in Note 18, Other Items and Charges, and to repay borrowings and/or debt securities.

Common Stock

The holders of the Class A common stock are entitled toone vote for each share held. The holders of the Class B common stock are entitled toten votes for each share held, except for the election of one director, who is elected by the holders of the Class A common stock exclusively. The Class B common stock is convertible into Class A common stock on a share-for-share basis at the option of the shareholder.

Preferred Stock

We are authorized to issue up to 944 shares of preferred stock in one or more series. As of December 31, 2025 and December 31, 2024, we hadno shares issued.

Stock Based Compensation

Stock Incentive Plans

Amended and Restated 2016 Incentive Plan. In fiscal year 2024, our stockholders approved the amendment and restatement of our 2016 Incentive Plan (the “Amended 2016 Plan”). Under the Amended 2016 Plan, we may grant awards up to an aggregate amount of shares equal to the sum of: (A)4,000 shares of Class A common stock (subject to adjustment in the event of stock splits and other similar events) which is comprised of: (i)1,750 shares of Class A common stock reserved for the issuance in connection with the Amended 2016 Plan, plus (ii)2,250 shares of Class A common stock originally reserved for issuance under the 2016 Incentive Plan; plus (B) such additional number of shares of Class A common stock (up to approximately 2,723 shares) as is equal to the sum of the number of shares of Class A common stock that remained available for grant under the 2006 Stock Incentive Plan (“2006 Plan”) immediately prior to the expiration of the 2006 Plan and the number of shares of Class A common stock subject to awards granted under the 2006 Plan that expire, terminate or are otherwise surrendered, canceled, forfeited or repurchased by us.

As of December 31, 2025, there were 2,080 Class A common stock equivalents available for future grant under the Amended 2016 Plan, inclusive of additional Class A common stock equivalents that were previously issued under terminated plans and have become available for grant because such awards expired or otherwise resulted in shares not being issued.

Our equity awards granted primarily consist of stock options, restricted stock awards, restricted stock units and market-based performance stock units.

Stock options are granted at a price equal to the prevailing fair value of our Class A common stock at the date of grant. Generally, stock options granted have a term not to exceedten years and vest over aone year tofive-year period from the date of grant.

The fair value of each stock option granted is estimated using a Black-Scholes option-pricing model, which uses a risk-free interest rate, based on the U.S. Treasury yield curve for the period of the expected life of the stock option; and requires extensive use of accounting judgment and financial estimation, including estimates of: the expected term, calculated based on the weighted average historical life of the vested stock options, giving consideration to vesting schedules and historical exercise patterns; and the expected volatility, calculated using the weekly historical volatility of our Class A common stock over the expected life of the stock option.

Restricted stock awards and restricted stock units are granted at a price equal to the fair value of our Class A common stock at the date of grant. The fair value of each market-based performance stock unit is estimated using a Monte Carlo pricing model, which requires extensive use of accounting judgment and financial estimation, including the estimated share price appreciation plus the value of dividends of our Class A common stock as compared to the Russell 2000 Index over the requisite service period.

Restricted stock awards granted to non-employee directors vest incrementally over athree-year period beginning on the first anniversary of the date of grant. Restricted stock units granted to non-employee directors vest in full on the first anniversary of the grant date. Restricted stock units vest incrementally over an identified service period beginning on the grant date based on continued employment. Market-based performance stock units vest at a future date following the grant date and are based on the attainment of performance targets and market achievements.

Stock Options

A summary of stock option activity is as follows:

During fiscal years 2025, 2024 and 2023, stock-based compensation expense for stock options was $540, $579 and $516, respectively.

During fiscal years 2025, 2024 and 2023, the aggregate intrinsic value of stock options exercised was $—, $2,625 and $1,302, respectively.

As of December 31, 2025, we had $988 of unrecognized stock-based compensation expense related to outstanding stock options to be recognized over a weighted average period of 2.0 years.

The Black-Scholes valuation model requires extensive use of accounting judgment and financial estimation. Application of alternative assumptions could produce significantly different estimates of the fair value of stock-based compensation and consequently, the related amounts recognized in the consolidated statements of operations.

Other Stock Awards

A summary of restricted stock award, restricted stock unit and performance stock unit activity is as follows:

(1)Performance stock unit grants are included at 100%. Attainment of maximum performance targets and market achievements would result in the issuance of an additional 141 shares of Class A common stock currently included in unvested. The market-based performance stock unit grants that vested in fiscal year 2025 resulted in the issuance of 10 additional shares of Class A common stock.

During fiscal years 2025, 2024 and 2023, stock-based compensation expense related to restricted stock awards, restricted stock units and performance stock units was $12,892, $11,001 and $8,116, respectively.

During fiscal years 2025, 2024 and 2023, the total fair value of other stock awards vested was $9,866, $8,409 and $12,048, respectively.

As of December 31, 2025, total unrecognized stock-based compensation expense related to outstanding restricted stock units was $6,544, which will be recognized over a weighted average period of 1.8 years. As of December 31, 2025, total unrecognized stock-based compensation expense related to performance stock units based on our estimated achievement of the established performance criteria was $9,504, which will be recognized over a weighted average period of 1.7 years.

The weighted average fair value of market-based performance stock units granted during fiscal year 2025 was $118.64 per award, which was calculated using a Monte Carlo pricing model assuming a risk-free interest rate of 3.95% and an expected volatility of 25.1% assumingno expected dividend yield. Risk-free interest rate is based on the U.S. Treasury yield curve for the expected service period of the award. Expected volatility is calculated using the daily volatility of our Class A common stock over the expected service period of the award.

The Monte Carlo pricing model requires extensive use of accounting judgment and financial estimation. Application of alternative assumptions could produce significantly different estimates of the fair value of stock-based compensation and consequently, the related amounts recognized in the consolidated statements of operations.

We also recorded $785, $607 and $451 of stock-based compensation expense related to our Second Amended and Restated 1997 Employee Stock Purchase Plan (“ESPP”) during fiscal years 2025, 2024 and 2023, respectively.

Tax benefit for income taxes associated with stock-based compensation during fiscal years 2025, 2024 and 2023 was $(4,123), $(1,907) and $(2,330), respectively.

Accumulated Other Comprehensive (Loss) Income, Net of Tax

Accumulated other comprehensive (loss) income, net of tax is a component of stockholders' equity included in the accompanying consolidated balance sheets and includes, as applicable, the effective portion of changes in the fair value of our cash flow hedges and the changes in fair value of our marketable securities. See Note 12, Debtfor further disclosure over cash flow hedges.

The changes in the balances of each component of accumulated other comprehensive (loss) income, net of tax are as follows:

A summary of reclassifications out of accumulated other comprehensive (loss) income, net of tax for fiscal years 2025, 2024 and 2023 is as follows:

15. FAIR VALUE OF FINANCIAL INSTRUMENTS

We use a three-tier fair value hierarchy to classify and disclose all assets and liabilities measured at fair value on a recurring basis, as well as assets and liabilities measured at fair value on a non-recurring basis, as applicable, in periods subsequent to their initial measurement. These tiers include: Level 1, defined as quoted market prices in active markets for identical assets or liabilities; Level 2, defined as inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; and Level 3, defined as unobservable inputs that are not corroborated by market data.

We use valuation techniques that maximize the use of market prices and observable inputs and minimize the use of unobservable inputs. In measuring the fair value of our financial assets and liabilities, we rely on market data or assumptions that we believe market participants would use in pricing an asset or a liability.

Assets and Liabilities Accounted for at Fair Value on a Recurring Basis

Our financial instruments include cash, cash equivalents and restricted cash, accounts receivable, restricted investment securities held in trust on deposit with various banks as collateral for our obligations relative to our landfill final capping, closure and post-closure costs, interest rate derivatives, trade payables and debt. The carrying values of cash, cash equivalents and restricted cash, accounts receivable and trade payables approximate their respective fair values due to their short-term nature. The fair value of restricted investment securities held in trust, which are valued using quoted market prices, are included as restricted assets in the Level 1 tier below. The fair value of interest rate derivatives included in the Level 2 tier below is calculated using discounted cash flow valuation methodologies based upon Term SOFR yield curves that are observable at commonly quoted intervals for the full term of the swaps. We recognize all derivatives accounted for on the balance sheet at fair value. See Note 12, Debt for disclosure about the fair value of debt.

Recurring Fair Value Measurements

Summaries of our financial assets and liabilities that are measured at fair value on a recurring basis are as follows:

16. EMPLOYEE BENEFIT PLANS

Defined Contribution Plan

We offer our eligible employees the opportunity to contribute to a 401(k) plan. Under the provisions of the 401(k) plans, participants may direct us to defer a portion of their compensation to a 401(k) plan, subject to Internal Revenue Code limitations. In fiscal year 2025, we provided an employer matching contribution for hourly employees equal to 100% of every dollar an employee invests up to 1% of annual income and 50% of additional employee contributions up to a maximum contribution into a 401(k) plan of 3% of annual income. In fiscal year 2025, we provided an employer matching contribution for salaried employees equal to 50% of every dollar an employee invests in a 401(k) plan up to a maximum contribution ofone thousand five hundred dollars or up to 2% of annual income, whichever is greater, per employee per calendar year. Participants vest in employer contributions ratable over atwo-year period. Employer contributions for fiscal years 2025, 2024 and 2023 amounted to $6,886, $5,831 and $4,371, respectively.

Employee Stock Purchase Plan

We offer our eligible employees the opportunity to participate in an employee stock purchase plan. Under the ESPP, qualified employees may purchase shares of Class A common stock by payroll deduction at a 15% discount from the market price. Class A common stock issued under our ESPP during fiscal years 2025, 2024 and 2023 amounted to 36,30 and 24 shares, respectively. As of December 31, 2025,341 shares of Class A common stock were available for distribution under our ESPP.

Defined Benefit Pension Plan

We contribute to a multiemployer defined benefit pension plan. The Pension Plan, under the terms of a collective bargaining agreement covers certain of our union represented employees. In the fiscal year ended December 31, 2019, we reached an agreement to withdraw from the Pension Plan by entering into Withdrawal and Re-entry Agreements with the Pension Plan. The withdrawal generated a fixed yearly contingent liability for us for a period of approximately seventeen (17) years, that capped our gross payments at $4,224, significantly reducing our cash exposure from the potential $18,511 withdrawal liability as determined based on a complete withdrawal prior to withdrawing from the Pension Plan. As of December 31, 2025, we had a remaining obligation of $1,305 in aggregate principal amount associated with our withdrawal. Upon re-entry as a new employer in the Pension Plan, our contributions are projected to fully fund the defined benefits accrued by our employees in the Pension Plan, thereby eliminating future accruals of withdrawal liability. As of December 31, 2025, our employees were fully funded, subject to the terms of the Withdrawal and Re-entry Agreements. Subsequent withdrawal from the Pension Plan, under certain circumstances, may result in a change in the payment schedule required to settle the remaining obligation associated with our withdrawal. During fiscal years 2025, 2024 and 2023, we made contributions to the Pension Plan of $793, $500 and $479, respectively.

17. INCOME TAXES

All pretax income from continuing operations is domestic. The components of the provision for income taxes are summarized as follows:

We adopted ASU 2023-09 on a prospective basis in fiscal year 2025. The differences in the provision for income taxes and the amounts determined by applying the federal statutory rate to income taxes are as follows:

Below is a tabular reconciliation of our effective tax rate to the United States federal income tax rate, as previously disclosed, and prior to the adoption of ASU 2023-09, for fiscal years 2024 and 2023, respectively.

In July 2025, H.R.1 - One Big Beautiful Bill Act (the “OBBB Act”) was enacted. The OBBB Act addresses a wide range of changes including reinstating 100% bonus depreciation eligible for qualified assets. The OBBB Act also restores the EBITDA-based computation of interest expense limitations under Section 163(j) of the Internal Revenue Code among other income tax items; any interest expense limited may be carried forward indefinitely and utilized in later years subject to the interest limitation. We have evaluated the impacts of the OBBB Act, both federal and state, for those provisions that impact fiscal year 2025.

Deferred income taxes reflect the impact of temporary differences between the amounts of assets and liabilities recognized for financial reporting purposes and such amounts recognized for income tax purposes. A summary of deferred tax assets and liabilities is as follows:

The net deferred tax liability at December 31, 2025 is reflected on the consolidated balance sheet as a long-term deferred federal and state tax liability of $(18,965).

As of December 31, 2025, we have net operating loss carryforwards for federal income tax purposes of approximately $124,227, of which $122,907 does not expire. We have state net operating loss carryforwards of approximately $156,096 that expire in the fiscal years ending December 31, 2026 through 2045 or that do not expire in certain jurisdictions. In addition, we have $4,291 general business credit carryforwards which expire in the fiscal years ending December 31, 2026 through 2045 and $1,606 state credit carryforwards, which are expected to begin expiring in fiscal years ending December 31, 2030 through 2040. Sections 382 and 383 of the Internal Revenue Code can limit the amount of net operating loss and credit carryforwards which may be used in a tax year in the event of certain stock ownership changes.

On a periodic basis, we reassess the valuation allowance on our deferred income tax assets, weighing positive and negative evidence to assess the recoverability of the deferred tax assets. In the fourth quarter of fiscal year 2025, we assessed the valuation allowance and considered positive evidence, including significant cumulative consolidated income over the three years ended December 31, 2025, revenue growth and expectations of future profitability, and negative evidence, including the impact of significant risks and uncertainties in the business and restrictions on tax loss utilization in certain state jurisdictions. After assessing both the positive evidence and the negative evidence, we determined it is more likely than not that certain state deferred tax assets would not be realized in the future. As of December 31, 2025, we maintained a valuation allowance of $9,056 primarily related to certain state net operating losses.

In assessing the realizability of carryforwards and other deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. We adjust the valuation allowance in the period management determines it is more likely than not that deferred tax assets will or will not be realized. The change in the valuation allowance for fiscal year 2025 was an increase of $600. In determining the need for a valuation allowance, we have assessed the available means of recovering deferred tax assets, including the ability to carryback net operating losses, the existence of reversing temporary differences, and available sources of future taxable income. We have also considered the ability to implement certain strategies, such as a potential sale of assets that would, if necessary, be implemented to accelerate taxable income and use expiring deferred tax assets.

The provisions of FASB ASC 740-10-25-5 prescribe the minimum recognition threshold that a tax position is required to meet before being recognized in the financial statements. Additionally, FASB ASC 740-10-25-5 provides guidance on derecognition, measurement, classification, interest and penalties, accounting in interim periods, disclosure and transition. Under FASB ASC 740-10-25-5, an entity may only recognize or continue to recognize tax positions that meet a “more likely than not” threshold. To the extent interest and penalties are not assessed with respect to uncertain tax positions, amounts accrued are reflected as a reduction of the overall income tax provision. As of December 31, 2025 and 2024, we didnot have any uncertain tax positions.

We are subject to U.S. federal income tax, as well as the income tax of multiple state jurisdictions. For federal tax purposes, income tax returns from years ending 2022 through 2025 are open for assessment. Tax years 2000 through 2021 are open for examination to the extent of any NOLs or credits that have been carried forward from those years.

In fiscal year 2025, state and local income taxes in Connecticut, Delaware and New York comprise the majority of the state and local income taxes, net of the federal effect category.

A summary of income taxes paid (refunded), net is as follows (in thousands):

18. OTHER ITEMS AND CHARGES

Expense from Acquisition Activities

In the fiscal years 2025, 2024 and 2023, we recognized expenses of $24,174, $24,879 and $15,038, respectively, comprised primarily of legal, consulting, rebranding, information technology and other costs associated with the due diligence, acquisition and integration of acquired businesses. Fiscal year 2024 includes a charge for an increase in the reserve against accounts receivable of the businesses acquired in the GFL Acquisition as a result of our inability to pursue collections during the transition services period with the seller, resulting in accounts receivable aged beyond what is typical in our business. See Note 6, Accounts Receivable, Net of Allowance for Credit Losses for disclosure over bad debt expense and Note 5, Business Combinations for disclosure regarding acquisition activity.

Organics Facility Closure Charge

In fiscal year 2025, we ceased operation of an organic residuals composting facility that we own in Maine related to a change in state law prohibiting land application of biosolids based recycled products.

A summary of our organics facility closure charge follows:

(1)We recorded a charge associated with our closure and post-closure obligations related to closing the site.

(2)We recorded an environmental remediation charge associated with an obligation incurred for corrective action linked to soil remediation at the site. See Note 13, Commitments and Contingenciesfor additional disclosure.

(3)We recorded other costs as incurred, and expect additional costs, associated with ceasing operations at the facility.

Southbridge Landfill Closure Charge

In the fiscal year ended December 31, 2017, we initiated a plan to cease operations of the Southbridge Landfill and later closed it in November 2018 when the Southbridge Landfill reached its final capacity. We received the Closure Permit in fiscal year 2024. Accordingly, we did not book any charges in fiscal year 2025. We recorded charges in 2024 and 2023 associated with the closure of the Southbridge Landfill as follows:

(1)We incurred legal costs as well as other transaction costs associated with various matters as part of the Southbridge Landfill closure.

(2)Includes a non-cash charge in fiscal year 2024 associated with the receipt of the Closure Permit from the Massachusetts Department of Environmental Protection related to the Southbridge Landfill. Pursuant to the terms of the Closure Permit, we are required to meet certain general permit conditions and certain specific permit conditions (collectively, the “Conditions”), including environmental monitoring, third-party inspections, inspection of the final cover, leachate sampling, post-closure monitoring and other post-closure requirements. We revised the accrued post-closure liability for the Southbridge Landfill to reflect the estimated cost of satisfying the expanded Conditions as currently specified in the Closure Permit. See Note 10, Final Capping, Closure and Post-Closure Costsfor disclosure regarding our landfill final capping, closure and post-closure costs.

Landfill Capping (Recovery) Charge - Veneer Failure

In fiscal year 2023, we recorded a charge of $3,870 consisting of both (i) the write-off of historical payments associated with capping work that was deemed no longer viable due to a veneer failure and (ii) the related operating expenses incurred to clean up the affected capping material at the Ontario County Landfill that we operate. In fiscal year 2024, we recorded a recovery of $(1,739) consisting of both (i) a partial reversal of historical payments written off after an engineering evaluation determined that a portion of the area affected by the veneer failure was deemed to still be viable as well as (ii) a recovery of operating expenses incurred during the clean up of the affected capping material as part of a settlement with a third party. See Note 10, Final Capping, Closure and Post-Closure Costsfor disclosure over our remaining estimated costs associated with obligations for final capping closure and post-closure of our landfills.

Legal Settlement

In fiscal year 2023, we recorded a charge of $6,150 due to reaching an agreement at a mediation held on June 20, 2023 with the collective class members of a class action lawsuit relating to certain claims under the Fair Labor Standards Act of 1938 as well as state wage and hours laws. The settlement agreement, which received court approval, was executed on July 24, 2023 and subsequently paid in fiscal year 2024.

19. EARNINGS PER SHARE

A summary of the numerator and denominators used in the computation of earnings per share is as follows:

(1)Adjustments associated with the timing of 5,175 shares of Class A common stock issued as part of the public offering, completed on September 19, 2024, and 6,053 shares of Class A common stock issued as part of the public offering, completed on June 16, 2023. See Note 14, Stockholders’ Equity for disclosure regarding the public offerings of Class A common stock.

20. RELATED PARTY TRANSACTIONS

Services

During fiscal years 2025, 2024 and 2023, we retained the services of Casella Construction, Inc. (“CCI”), a company substantially owned by sons of John Casella, our Executive Chairman of the Board of Directors, and Douglas Casella, a member of our Board of Directors, as a contractor providing transportation and construction services. Total purchased services charged to operations or capitalized to landfills for fiscal years 2025, 2024 and 2023 were $8,559, $7,762 and $7,682, respectively, of which $613 and $477 were outstanding and included in either accounts payable or other current liabilities as of December 31, 2025 and December 31, 2024, respectively.

In addition to the total purchased services, we provided various waste collection and disposal services to CCI. Total revenues recorded for fiscal years 2025, 2024 and 2023 were $320, $242 and $241, respectively.

Leases

In the fiscal year ended April 30, 1994, we entered intotwo leases for operating facilities with a partnership of which John Casella, our Executive Chairman of the Board of Directors, and Douglas Casella, a member of our Board of Directors, are the general partners. The lease related to our corporate headquarters in Rutland, Vermont has been extended through February 2039 and the lease associated with our Montpelier, Vermont facility has been extended through May 2039. The terms of the lease agreements require monthly payments of approximately $35, subject to a fixed annual escalation. Total expense charged to operations for fiscal years 2025, 2024 and 2023 under these agreements was $607, $554 and $284, respectively.

Landfill Post-closure

We have agreed to pay the cost of post-closure on a landfill owned by John Casella, our Executive Chairman of the Board of Directors, and Douglas Casella, a member of our Board of Directors. We paid the cost of closing this landfill in 1992, and the post-closure maintenance obligations are expected to last until notified by the permitting authority. In fiscal years 2025, 2024 and 2023, we paid $4, $14 and $3, respectively, pursuant to this agreement. As of December 31, 2025 and December 31, 2024, we have accrued $14 and $17, respectively, for costs associated with its post-closure obligations.

21. SEGMENT REPORTING

We report selected information about our reportable operating segments in a manner consistent with that used for internal management reporting. We classify our solid waste operations on a geographic basis through three regional operating segments, our Eastern, Western and Mid-Atlantic regions. In fiscal year 2025, we moved certain operations between our regional operating segments to align geographically, including a landfill that we own from the Western region to the Mid-Atlantic region and a collection and transfer station operation from our Western region to our Eastern region. Certain prior period amounts have been reclassified between regional operating segments to conform to the current period presentation.

Revenues associated with our solid waste operations are derived mainly from solid waste collection and disposal services, including landfill, transfer station and transportation services, landfill gas-to-energy services and processing services in the eastern United States. Our Resource Solutions operating segment leverages our core competencies in materials processing, industrial recycling, organics and resource management service offerings to deliver a comprehensive solution for our larger commercial, municipal, institutional and industrial customers that have more diverse waste and recycling needs. Revenues associated with our Resource Solutions operations are comprised of processing services and services provided by our National Accounts business. Revenues from processing services are derived from customers in the form of processing fees, tipping fees, commodity sales, and organic material sales. Revenues from our National Accounts business are derived from brokerage services and overall resource management services providing a wide range of environmental services and resource management solutions to large and complex organizations, as well as traditional collection, disposal and recycling services provided to large account multi-site customers. Legal, tax, information technology, human resources, certain finance and accounting and other administrative functions are included in our Corporate Entities segment, which is not a reportable operating segment. For comparative purposes, summarized financial information by segment reported in fiscal years 2024 and 2023 has been updated to conform with the presentation for fiscal year 2025, related to the movement of certain operations described above. In addition, we have voluntarily corrected certain amounts in the tables below for fiscal years 2024 and 2023 to correct an immaterial error in previously issued segment footnote disclosure by reclassifying certain intercompany amounts from contra-revenue recorded in our Eastern and Western regions to costs of operations for those same regions, with no impact on any measure of segment operating income (loss) or our consolidated balance sheet, earnings, or cash flows. See Note 9, Goodwill and Intangible Assets for the breakout of goodwill by reportable operating segment.

The accounting policies of our reportable operating segments are the same as those described in Note 3, Summary of Significant Accounting Policies. Our President and Chief Executive Officer is our CODM. Our CODM uses operating income in evaluating reportable operating segment performance in order to properly allocate resources and make key operating decisions. Intercompany revenue and expenses are eliminated in the computation of consolidated gross revenues and operating income.

The CODM uses operating income for each reportable operating segment in the annual budget and forecasting process and considers budget-to-actual and forecast-to-actual variances on a monthly basis when making decisions about the allocation of operating and capital resources to each reportable operating segment.

Summarized financial information concerning our reportable segments for fiscal years 2025, 2024 and 2023, follows:

Fiscal Year Ended December 31, 2025:

Fiscal Year Ended December 31, 2024:

Fiscal Year Ended December 31, 2023:

(1)Operations associated with the GFL acquisition under the Mid-Atlantic region commenced July 1, 2023.

A summary of our revenues attributable to services provided follows: