COMPASS MINERALS INTERNATIONAL INC

Notes to Consolidated Financial Statements

1. ORGANIZATION AND FORMATION

Compass Minerals International, Inc. (“CMI”), through its subsidiaries (collectively, “CMP,” “Compass Minerals” or the “Company”), is a leading global provider of essential minerals focused on safely delivering where and when it matters to help solve nature’s challenges for customers and communities. The Company’s salt products help keep roadways safe during winter weather and are used in numerous other consumer, industrial, chemical and agricultural applications. Its plant nutrition business is the leading North American producer of sulfate of potash (“SOP”), which is used in the production of specialty fertilizers for high-value crops and turf and helps improve the quality and yield of crops, while supporting sustainable agriculture. The Company’s principal products are salt, consisting of sodium chloride and magnesium chloride, and SOP. The Company’s production sites are located in the United States (“U.S.”), Canada and the United Kingdom (“UK”). The Company also provides records management services in the UK.

CMI is a holding company with no significant operations other than those of its wholly-owned subsidiaries.

Fortress

Beginning in 2020, the Company began a series of equity investments in Fortress, a fire retardant company working to develop long-term fire retardant solutions to help combat wildfires. On November 2, 2021, the Company announced its increased investment in Fortress. On May 5, 2023, the Company acquired the remaining 55% interest in Fortress not previously owned in exchange for an initial cash payment of $18.9 million (net of cash held by Fortress of $6.5 million), and additional contingent consideration of up to $28 million to be paid in cash and/or Compass Minerals common stock upon the achievement of certain performance measures over five years, and a cash earn-out based on financial performance and volumes of certain Fortress fire retardant products sold over a 10-year period. By acquiring 100% of Fortress, the transaction provided the Company full ownership of all Fortress assets, contracts, and intellectual property.

On March 25, 2025, the Company took measures to align the Company’s cost structure to its current business needs as part of a larger strategic refocus to improve the profitability of the Company’s core Salt and Plant Nutrition businesses. Specifically, the Company began the process of exiting the Fortress fire retardant business and terminating the employment of all Fortress employees.

On May 30, 2025, the Company entered into an Asset Purchase Agreement, selling substantially all of the remaining Fortress-related assets for $19.6 million, net of transaction costs, including the remaining $2.2 million of indefinite-lived in process research and development intangible asset. The sale of the Fortress long-lived assets included in Property, plant and equipment had a net book value of approximately $15.0 million. The fair value of proceeds received, net of transaction costs, exceeded the carrying amount, resulting in a gain of $2.4 million, recorded in Other (income) expense, net, on the Consolidated Statements of Operations for the fiscal year ended September 30, 2025. See Note 6. Property, Plant and Equipment and Note 7. Goodwill and Other Intangible Assets for further information.

Presentation

In the Consolidated Balance Sheets, Current portion of finance lease liabilities and Finance lease liabilities, net of current portion have been presented separately from Accrued expenses and other current liabilities and Other noncurrent liabilities line items, respectively, in the current year presentation, with conforming reclassifications made for the prior period presentation.

Certain Selling, general and administrative expenses totaling $4.4 million have been reclassified in fiscal year ended September 30, 2023 to Other operating (income) expense to conform to current year presentation. The amounts that have been reclassified in fiscal year ended September 30, 2023 include employee termination costs related to restructuring and executive transition costs of $5.5 million, Securities and Exchange Commission (the “SEC”) investigation and related legal costs, net of reimbursements, of $(0.3) million, and changes in fair value of contingent consideration related to the acquisition of Fortress North America, LLC (“Fortress”) of $(0.8) million. The reclassification was made to separately report infrequent or other items from Selling, general and administrative expenses.

In the Consolidated Statements of Cash Flows, certain immaterial line items included in cash flows from operating activities have been reclassified to Other, net, included in cash flows from operating activities.

2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Management Estimates. The preparation of consolidated financial statements in conformity with U.S. Generally Accepted Accounting Principles (“GAAP”) as included in the Accounting Standards Codification (“ASC”) requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from those estimates.

Basis of Consolidation. The Company’s consolidated financial statements include the accounts of CMI and its wholly-owned domestic and foreign subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation.

Revenue Recognition. The FASB revenue recognition guidance provides a single, comprehensive model for recognizing revenue from contracts with customers. The revenue recognition model requires revenue to be recognized upon the transfer of promised goods or services to customers in an amount that reflects the consideration an entity expects to receive in exchange for those goods or services. The Company’s revenue arrangements generally consist of a single performance obligation to transfer promised goods or services. Prior to fiscal year ended September 30, 2025, the Company derived revenues from a full-service air base fire retardant contract with the United States Forest Service (“USFS”), which is comprised ofthree performance obligations, namely product sales, providing operations and maintenance personnel services and leasing of specified equipment. Substantially all of the Company’s revenue is recognized at a point in time when control of the goods transfers to the customer.

The Company typically recognizes revenue at the time of shipment to the customer, which coincides with the transfer of title and risk of ownership to the customer. Sales represent billings to customers net of sales taxes charged for the sale of the product. Sales include amounts charged to customers for shipping and handling costs, which are expensed when the related product is sold.

Fortress Contingent Consideration. On March 25, 2025, the Company announced it was exiting the Fortress fire retardant business. Previously, the Company entered into a contingent consideration arrangement in connection with the acquisition of Fortress for up to $28 million to be paid in cash and/or Compass Minerals common stock upon the achievement of certain performance measures over five years, and a cash earn-out based on volumes of certain Fortress fire retardant products sold over a 10-year period. The approach to valuing the initial contingent consideration associated with the purchase price, including milestone achievement and the earn-out, uses unobservable factors such as projected revenues and expenses over the term of the contingent milestone achievement and earn-out periods, discounted for the period of time over which the initial contingent consideration is measured. The milestone contingent consideration related to the Fortress acquisition was paid in cash and/or Compass Minerals common stock, at the Company’s discretion, at a fixed price of approximately $32 per share upon the achievement of certain performance measures. This fixed share price settlement option was also factored into the fair value of the milestone contingent consideration. The fair value of the milestone contingent consideration was estimated using a probability-weighted discounted cash flow model, including a Black-Scholes option value related to a share conversion feature with significant inputs not observable in the market and is therefore considered a Level 3 measurement while the earn-out was valued using a Monte Carlo simulation, also a Level 3 measurement.

The changes in contingent consideration liability were recorded in Other operating (income) expense in the Consolidated Statements of Operations to reflect the liability at its fair value. For the fiscal years ended September 30, 2025, September 30, 2024 and September 30, 2023, the Company recorded net gains of $7.9 million, $22.1 million and $0.8 million, respectively, included in other operating income. Given the business ceased operations and had no future expected cash flows in the fiscal year ended September 30, 2025, the carrying value of the contingent consideration was reduced to $0 as of March 31, 2025. The change in the fiscal year ended September 30, 2024 was reflective of milestone and earn-out payments made related to calendar year 2023 activity, developments related to the Company’s magnesium chloride-based fire retardants, changes in discount rates and the passage of time. The change in the fiscal year ended September 30, 2023 was reflective of changes in discount rates and the passage of time. See Note 1. Organization and Formation for further information regarding the exit of the Fortress fire retardant business.

Impairments. The following tables summarize the Company’s assets that were impaired for the periods presented below (in millions):

Fiscal 2025 impairments. As a result of steps taken to exit the Fortress fire retardant business on March 25, 2025, the Company determined that there were indicators of impairment with the associated Fortress intangible assets. Therefore, the Company tested these intangible assets for impairment and recorded a loss on impairment of $53.0 million for the fiscal year ended September 30, 2025, related to customer relationships and trade name.

Additionally, the Company performed an impairment test on the remaining Fortress asset group (including PP&E), inventory and in-process research and development (“IPR&D”), with a carrying amount of $19.7 million. The impairment test under ASC 360, Property, Plant Equipment and Other Assets, compared the asset group’s undiscounted cash flows to its carrying amount. The Company determined the fair value of the asset group using a market approach under ASC 820, Fair Value Measurement (Level 2 inputs, see Note 15. Fair Value Measurements). The asset group (PP&E, inventory and IPR&D) was not impaired as its fair value, based on market indications, approximated or exceeded its carrying value and the assets were subsequently either sold or disposed of at its approximate fair value.

At June 30, 2025, the Company performed an impairment test on the remaining Fortress asset group related PP&E and recorded a loss on impairment of $0.7 million, during the fiscal year ended September 30, 2025. See Note 15. Fair Value Measurements for further information.

Fiscal 2024 impairments. On January 23, 2024, the Company terminated its pursuit of its lithium development. The passage of Utah House Bill 513 in March 2023 and the subsequent rulemaking process altered certain aspects of the regulatory landscape that will govern the development of lithium at the Great Salt Lake, introducing uncertainty into how development would proceed. As previously disclosed in the Company’s 2023 Form 10-K, the Company indefinitely paused new investment in its lithium development project pending greater clarity on the evolving regulatory environment in Utah. In December of 2023, a revised draft of the aforementioned rulemaking was published that continued to be, in the Company's assessment, adverse to its lithium development project. In addition, in December of 2023, the Company further refined its engineering estimates that, taken together with the proposed rules and decline in market price for lithium products, would result in inadequate risk-adjusted returns on capital.

On January 23, 2024, the Company severed certain members of its lithium development team and terminated its pursuit of the lithium development. Consequently, the Company evaluated the capitalized assets, including site preparation, project engineering, equipment and materials and capitalized labor and interest. As a result, the Company recorded an impairment charge of $74.8 million, including $7.6 million associated with future commitments for the year ended September 30, 2024 to

reflect the assets at their estimated fair value, considering equipment expected to be used by the on-going business and amounts estimated to be recoverable through returns or salvage value. Prior to recording an impairment, the Company had capitalized $72.7 million to its property, plant and equipment on its Consolidated Balance Sheet with approximately $4.8 million of spare parts remaining in inventories as of September 30, 2024. The Company engaged a valuation specialist to assist in determining the appropriate fair value of the lithium assets and the resulting impairment charge. Given the assets are likely to either be used in other operations or liquidated at a later date, the Company utilized a market-based approach that relied on Level 3 inputs (see Note 15. Fair Value Measurements for a discussion of the levels in the fair value hierarchy).

As a result of a sustained decrease in the Company’s publicly quoted share price and market capitalization continuing into fiscal 2024 and developments related to its magnesium chloride-based fire retardants impacting its Fortress business, the Company determined in the second quarter of fiscal 2024 that there were indicators of impairment and therefore performed long-lived assets and goodwill impairment testing. The analysis for Plant Nutrition resulted in no long-lived asset impairment but did result in a goodwill impairment, as discussed further below. The Fortress analysis resulted in an impairment of the Company’s magnesium chloride-related assets and goodwill; see below for additional details.

On March 22, 2024, the Company was notified of the decision by the U.S. Forest Service that the Company would not be awarded a contract to supply its magnesium chloride-based aerial fire retardant for the calendar 2024 fire season. For purposes of the long-lived asset impairment evaluation, management grouped and tested the magnesium chloride-related assets given their unique classification and separately identifiable cash flows. As a result of the evaluation using the income approach, the Company impaired all magnesium chloride-related assets which resulted in a finite-lived intangible asset impairment of $15.6 million related to the Company’s developed technology intangible asset and an impairment of $2.4 million of inventory for the fiscal year ended September 30, 2024. The long-lived asset impairment is included in loss on impairments, while the inventory impairment is reflected in product cost, both on the Consolidated Statements of Operations. The undiscounted cash flows for the remaining Fortress assets were greater than their carrying value resulting in no incremental impairment.

The Company performed the interim goodwill impairment tests consistent with its approach for annual impairment testing, including using similar models, inputs and assumptions. As a result of the interim goodwill impairment test in the second quarter of fiscal 2024, the Company recognized impairment charges totaling $83.0 million included in loss on impairments, on the Consolidated Statements of Operations for the fiscal year ended September 30, 2024. Goodwill impairment of $51.0 million was related to the Company’s Plant Nutrition segment, primarily due to decreases in projected future revenues and cash flows and an increase in discount rates due to the uncertain regulatory environment in Utah. The remaining goodwill impairment of $32.0 million was related to the Company’s Fortress reporting unit (included in the Corporate and Other segment), primarily due to changes in assumptions surrounding the magnesium chloride-based fire retardants which impacted projected future revenues and cash flows. Following the impairment charges, there is no remaining goodwill balance for the Plant Nutrition and Fortress reporting units. Refer to Note 7. Goodwill and Other Intangible Assets for a summary of goodwill by segment.

On September 3, 2024, the Company announced a binding Voluntary Agreement (“Voluntary Agreement”) with the Utah Division of Forestry, Fire and State Lands (“FFSL”) outlining water and land conservation commitments the Company is making toward the long-term health of the Great Salt Lake. Per the terms of the Voluntary Agreement, the Company completed the donation of the non-production-related water rights totaling approximately 201,000 acre feet annually to be used by the State of Utah for lake conservation and preservation during the fiscal year ended September 30, 2025. In connection with the annual impairment analysis, the Company performed a fair value analysis of the indefinite-lived intangible asset that resulted in animpairment of approximately $17.6 million.

Foreign Currency. Assets and liabilities are translated into U.S. dollars at end of period exchange rates. Sales and expenses are translated using the monthly average rates of exchange during the year. Adjustments resulting from the translation of foreign-currency financial statements into the reporting currency, U.S. dollars, are included in accumulated other comprehensive loss. The Company recorded foreign exchange gain (loss) of $2.0 million, $(0.2) million and $(1.6) million for the fiscal years ended September 30, 2025, September 30, 2024, and September 30, 2023, respectively, in accumulated other comprehensive loss related to intercompany notes which, had been deemed to be of long-term investment nature. Aggregate exchange losses and gains from transactions denominated in a currency other than the functional currency, which are included in other (income) expense for the fiscal years ended September 30, 2025, September 30, 2024, and September 30, 2023, were $(0.1) million, $0.7 million and $2.3 million, respectively. These amounts include the effect of translating intercompany notes which were deemed to be temporary in nature.

Cash and Cash Equivalents. The Company considers all investments with original maturities of three months or less to be cash equivalents. The Company maintains the majority of its cash in bank deposit accounts with several commercial banks with high credit ratings in the U.S., Canada, and the UK. Typically, the Company has bank deposits in excess of federally insured limits. Currently, the Company does not believe it is exposed to significant credit risk on its cash and cash equivalents.

Accounts Receivable and Allowance for Credit Losses. Receivables consist of trade accounts receivable and miscellaneous receivables. Trade accounts receivable are recorded at the invoiced amount and do not bear interest. Miscellaneous receivables includes amounts pertaining to insurance receivables. See Note 3. Revenues for further information on trade account receivable and miscellaneous receivable balances and Note 11. Commitments and Contingencies for additional information regarding insurance miscellaneous receivables. The allowance for credit losses is the Company’s best estimate of the amount of expected credit losses in its existing trade accounts receivable. The Company determines the allowance based on historical write-off experience, adjusted for current and expected future conditions. The Company reviews its account balances for collectability and adjusts its allowance for credit losses on a quarterly basis, or more frequently if conditions warrant. Account balances are charged off against the allowance for credit losses when the Company deems the amounts to be uncollectible and it is probable that the trade accounts receivable will not be recovered.

Inventories. Inventories are stated at the lower of cost or net realizable value. Finished goods, work in process and raw material are predominately valued using the average cost method on a first-in-first-out basis. Spare parts and supply costs are valued at average costs. Work in process costs primarily consist of costs incurred to operate the Company’s evaporation ponds prior to their harvest. Raw materials and supply costs primarily consist of raw materials purchased to aid in the production of mineral products, maintenance materials and packaging materials. Finished goods are primarily comprised of salt, magnesium chloride, SOP products and fire retardants readily available for sale. Substantially all costs associated with the production of finished goods at the Company’s production locations are captured as inventory costs. As required by GAAP, a portion of the fixed costs at a location are not included in inventory and are expensed as a product cost if production at that location is determined to be abnormally low in any period or if the nature of the cost incurred is not attributable to its production processes. Additionally, since the Company’s products are often stored at warehousing locations, the Company includes in the cost of inventory the freight and handling costs necessary to move the product to storage until the product is sold to a customer.

Other Current Assets. The items included in other current assets as of September 30, 2025 and September 30, 2024, consist principally of prepaid expenses of $20.9 million and $26.9 million, respectively.

Property, Plant and Equipment. Property, plant and equipment is stated at cost and includes capitalized interest. The costs of replacements or renewals, which improve or extend the life of existing property, are capitalized. Maintenance and repairs are expensed as incurred. Upon retirement or disposition of an asset, any resulting gain or loss is included in the Company’s operating results.

Property, plant and equipment also includes mineral interests. The mineral interests for the Company’s Winsford UK mine are owned. The Company leases probable mineral reserves at its Cote Blanche and Goderich mines, its Ogden facility and several of its other North American facilities. These leases have varying terms, and many provide for a royalty payment to the lessor based on a specific amount per ton of mineral extracted or as a percentage of sales. The Company’s rights to extract minerals are contractually limited by time. The Cote Blanche mine is operated under land and mineral leases, and the mineral lease expires in 2060 withtwo additional 25-year renewal periods. The Goderich mine mineral reserve lease expires in 2043 with the Company’s option to renew for an additional twenty-one years after demonstrating to the lessor that the mine’s useful life is greater than the lease’s term. The Ogden facility mineral reserve lease renews annually. The Company believes it will be able to continue to extend lease agreements as it has in the past, at commercially reasonable terms, without incurring substantial costs or material modifications to the existing lease terms and conditions, and therefore, management believes that assigned lives are appropriate. The Company’s mineral interests are depleted on a units-of-production basis based upon the latest available mineral study. The weighted average amortization period for the leased probable mineral reserves is 84 years as of September 30, 2025. The Company also owns other mineral properties. The weighted average life for the probable owned mineral reserves is 32 years as of September 30, 2025, based upon management’s current production estimates.

Buildings and structures are depreciated on a straight-line basis over lives generally ranging from 10 to 30 years. Portable buildings generally have shorter lives than permanent structures. Leasehold and building improvements have estimated lives of 5 to 40 years or lower based on the life of the lease to which the improvement relates.

The Company’s fixed assets are amortized on a straight-line basis over their respective lives. The following table summarizes the estimated useful lives of the Company’s different classes of property, plant and equipment:

The Company has finance leases which are recorded in property, plant and equipment at the beginning of the lease at the lower of the fair value of the leased property or the present value of the minimum lease payments. Lease payments are recorded as interest expense and a reduction of the lease liability. A finance lease right-of-use asset is amortized over the lower of its useful life or the lease term.

The Company has capitalized computer software costs of $0.8 million and $3.0 million as of September 30, 2025 and September 30, 2024, respectively, recorded in property, plant and equipment. The capitalized costs are being amortized over a range ofthree tofive years. The Company recorded $0.9 million, $1.6 million and $3.3 million of amortization expense related to capitalized computer software for the fiscal years ended September 30, 2025, September 30, 2024, and September 30, 2023, respectively.

The Company recognizes and measures obligations related to the retirement of tangible long-lived assets in accordance with applicable U.S. GAAP. Asset retirement obligations are not material to the Company’s consolidated financial position, results of operations or cash flows.

The Company reviews its long-lived assets and the related mineral reserves for impairment whenever events or changes in circumstances indicate the carrying amounts of such assets may not be recoverable. If an indication of a potential impairment exists, recoverability of the respective assets is determined by comparing the forecasted undiscounted net cash flows of the operation to which the assets relate, to the carrying amount, including associated intangible assets, of such operation. If the operation is determined to be unable to recover the carrying amount of its assets, then intangible assets are written down first, followed by the other long-lived assets of the operation, to fair value. Fair value is determined based on discounted cash flows or appraised values, depending upon the nature of the assets. See the “Impairments” section above within Note 2. Summary of Significant Accounting Policies for information regarding the loss on impairments of long-lived assets for the fiscal years ended September 30, 2025 and September 30, 2024. During the fiscal year ended September 30, 2023, there wereno loss on impairments of long-lived assets recorded.

Leases. In accordance with U.S. GAAP, lessees are required to recognize on their balance sheet a right-of-use asset which represents a lessee’s right to use the underlying asset, and a lease liability which represents a lessee’s obligation to make lease payments for the right-of-use asset. In addition, the guidance requires expanded qualitative and quantitative disclosures. Refer to Note 4. Leases for additional details.

Intangible Assets. The Company amortizes its intangible assets deemed to have finite lives on a straight-line basis over their estimated useful lives which, for the Company, range from 10 to 50 years. The Company evaluates definite-lived intangible assets whenever events or changes in circumstances indicate that the carrying amount of the asset group may not be fully recoverable. During fiscal years ended September 30, 2025, September 30, 2024, and September 30, 2023, the Company recorded a loss on impairment of definite-lived intangible assets of $53.0 million, $15.6 million, and $0.0 million, respectively.

An intangible asset with an indefinite useful life is not amortized but assessed for impairment at least annually, or sooner if indications of possible impairment are identified. When performing the annual impairment test, the Company first may start with an optional qualitative assessment to determine whether it is not more likely than not that the indefinite-lived intangible assets are impaired. If the Company does not elect to use the qualitative assessment, or if the qualitative assessment indicates that a quantitative analysis should be performed, the Company evaluates the indefinite-lived intangible assets for impairment by comparing the fair value of the asset to its carrying amount. The Company performed a qualitative impairment test as of September 30, 2025, and concluded that it was not more likely than not that the fair value of the indefinite-lived intangible

assets had been reduced below their respective carrying amounts and therefore, no indefinite-lived intangible asset impairment charges were incurred. During the fiscal year ended September 30, 2024, the Company recorded a loss on impairment of indefinite-lived intangible assets related to water rights of $17.6 million, included in the Plant Nutrition segment. During the fiscal year ended September 30, 2023, there wereno indefinite-lived intangible asset impairment charges incurred.

Goodwill. The Company’s recorded goodwill was $6.0 million as of both September 30, 2025 and September 2024. The Company evaluates goodwill for impairment annually as of the beginning of the fourth quarter and any time an event occurs or circumstance change that would more likely than not reduce the fair value for a reporting unit below its carrying amount. The Company has an option to first assess the qualitative factors to determine whether it is more likely than not that the fair value of the goodwill recorded in Corporate and Other had been reduced below its respective carrying amounts, as a basis for determining whether it is necessary to perform the quantitative goodwill impairment test. During the fourth quarter of fiscal 2025, the Company assessed the qualitative factors and reached a determination that it is not more likely than not that the fair value of the Company’s Corporate and Other reporting unit was less than its carrying value, and therefore, no impairment charge was incurred. See the “Impairments” section above within Note 2. Summary of Significant Accounting Policies for information regarding the loss on impairments of goodwill for the fiscal year ended September 30, 2024.

Other Noncurrent Assets. Other noncurrent assets include certain spare parts, net of reserve, of $33.0 million and $42.2 million at September 30, 2025 and September 30, 2024, respectively. As of September 30, 2025 and September 30, 2024, other noncurrent assets also include right-of-use operating lease assets, net of amortization, of $52.3 million and $50.0 million, respectively.

Non-Qualified Defined Contribution Plan. The Company sponsors a non-qualified defined contribution plan for certain of its executive officers and key employees as described in Note 9. Pension Plans and Other Benefits. As of September 30, 2025 and September 30, 2024 investments in marketable securities representing amounts deferred by employees, Company contributions and unrealized gains or losses totaling $3.5 million and $3.1 million, respectively, were included in other noncurrent assets in the Consolidated Balance Sheets. The marketable securities are classified as trading securities and accordingly, gains and losses are recorded as a component of other expense, net in the Consolidated Statements of Operations.

Income Taxes. The Company accounts for income taxes using the liability method in accordance with the provisions of U.S. GAAP. Under the liability method, deferred taxes are determined based on the differences between the consolidated financial statements and the tax basis of assets and liabilities using enacted tax rates in effect in the years in which the differences are expected to reverse. The Company’s foreign subsidiaries file separate company returns in their respective jurisdictions.

The Company recognizes potential liabilities in accordance with applicable U.S. GAAP for anticipated tax issues in the U.S. and other tax jurisdictions based on its estimate of whether, and the extent to which, additional taxes will be due. If payment of these amounts ultimately proves to be unnecessary, the reversal of the liabilities would result in tax benefits being recognized in the period when the Company determines the liabilities are no longer necessary. If the Company’s estimate of tax liabilities proves to be less than the ultimate assessment, a further charge to expense would result. Any penalties and interest that are accrued on the Company’s uncertain tax positions are included as a component of income tax expense.

In evaluating the Company’s ability to realize deferred tax assets, the Company considers the sources and timing of taxable income, including the reversal of existing temporary differences, the ability to carryback tax attributes to prior periods, qualifying tax-planning strategies, and estimates of future taxable income exclusive of reversing temporary differences. In determining future taxable income, the Company’s assumptions include the amount of pre-tax operating income according to different state, federal and international taxing jurisdictions, the origination of future temporary differences, and the implementation of feasible and prudent tax-planning strategies. In situations where a three-year cumulative loss condition exists, accounting standards limit the ability to consider projections of future results as positive evidence to assess the realizability of deferred tax assets. Valuation allowances are established when it is estimated that it is more likely than not that the tax benefit of the deferred tax asset will not be realized.

If the Company determines that a portion of its deferred tax assets will not be realized, a valuation allowance is recorded in the period that such determination is made. In the future, if the Company determines, based on the existence of sufficient evidence, that more or less of the deferred tax assets are more likely than not to be realized, an adjustment to the valuation allowance will be made in the period such a determination is made.

Environmental Costs. Environmental costs, other than those of a capital nature, are accrued at the time the exposure becomes known and costs can be reasonably estimated. Costs are accrued based upon management’s estimates of all direct costs. Amounts reserved for environmental matters were not material at September 30, 2025 or September 30, 2024.

Equity Compensation Plans. The Company has equity compensation plans under the oversight of the Company’s Board of Directors, whereby stock options, restricted stock units, performance stock units, deferred stock units and shares of common stock are granted to the Company’s employees and directors. The Company elected to estimate forfeitures of unvested awards when recognizing stock-based compensation expense. The forfeiture rate is based on historical experience. Compensation cost is adjusted to reflect actual forfeitures as they occur. See Note 13. Stockholders’ Equity and Equity Instruments for additional discussion.

Net (Loss) Income Per Share. When calculating net (loss) income per share, the Company’s participating securities are accounted for under the two-class method in periods in which dividends are declared. In the second fiscal quarter of 2024, the Company ceased paying dividends. The two-class method requires allocating the Company’s net income to both common shares and participating securities based upon their rights to receive dividends. Net (loss) income per share is computed by dividing net income available to common stockholders by the weighted-average number of outstanding common shares during the period. Diluted income per share reflects the potential dilution that could occur under the more dilutive of either the treasury stock or the two-class method for calculating the weighted-average number of outstanding common shares. The treasury stock method is calculated assuming unrecognized compensation expense, income tax benefits and proceeds from the potential exercise of employee stock options are used to repurchase common stock.

Derivatives. The Company is exposed to the impact of fluctuations in the purchase price of natural gas, diesel fuel consumed in operations and fuel costs incurred to deliver its products to its customers. The Company may hedge portions of these risks through the use of derivative agreements.

The Company records derivative financial instruments as assets or liabilities measured at fair value. Accounting for the changes in the fair value of a derivative depends on its designation and effectiveness. Derivatives qualify for treatment as hedges when there is a high correlation between the change in fair value of the derivative instrument and the related change in value of the underlying hedged item. For qualifying hedges, the effective portion of the change in fair value is recognized through earnings when the underlying transaction being hedged affects earnings, allowing a derivative’s gains and losses to offset related results from the hedged item in the Consolidated Statements of Operations. Until the effective portion of a derivative’s change in fair value is recognized in the Consolidated Statements of Operations, the change in fair value is recognized in other comprehensive income. The Company presents derivatives on a net basis when subject to master netting agreements and when the right of offset exists. For derivative instruments that are not accounted for as hedges, or for the ineffective portions of qualifying hedges, the change in fair value is recorded through earnings in the period of change. The Company formally documents, designates and assesses the effectiveness of transactions that receive hedge accounting treatment initially and on an ongoing basis.

Concentration of Credit Risk. The Company sells its salt and magnesium chloride products to various governmental agencies, manufacturers, distributors and retailers primarily in the Midwestern U.S. and throughout Canada and the UK. The Company’s plant nutrition products are sold across the Western Hemisphere and globally. No single customer or group of affiliated customers accounted for more than 10% of the Company’s sales during the fiscal years ended September 30, 2025, September 30, 2024, and September 30, 2023, or more than 10% of receivables at September 30, 2025 or September 30, 2024.

Accounting Pronouncement Recently Adopted

Segment Reporting. In November 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2023-07, “Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures”, which updates reportable segment disclosure requirements primarily to include enhanced disclosures about significant segment expenses. The Company adopted ASU 2023-07 in fiscal 2025 and applied the amendment retrospectively to all periods presented in the Company’s consolidated financial statements. See Note 12. Operating Segments for more information.

Accounting Pronouncements Issued Not Yet Adopted

Income Tax Disclosures. In December 2023, the FASB issued ASU 2023-09, “Income Taxes (Topic 740): Improvements to Income Tax Disclosures”, which updates income tax disclosures by requiring consistent categories and additional disaggregation of information in the rate reconciliation and income taxes paid by jurisdiction. The ASU is effective for fiscal years beginning after December 15, 2024, and is effective for the Company beginning in the annual report for the fiscal year ended September 30, 2026. Early adoption is permitted. The amendments should be applied prospectively; however, retrospective application is permitted. Management is currently evaluating this ASU to determine its impact on the Company’s disclosures.

Disaggregation of Income Statement Expenses. In November 2024, the FASB issued amended guidance related to disclosure of disaggregated expenses (“ASU 2024-03”). This amendment requires public business entities to provide detailed disclosures in the notes to financial statements disaggregating specific expense categories, including employee compensation, depreciation, and intangible asset amortization, as well as certain other disclosures to provide enhanced transparency into the nature and function of expenses. This guidance is effective for annual periods beginning in the Company’s annual report for the fiscal year ended September 30, 2028 and interim periods following annual adoption, with early adoption permitted. This guidance will be applied on a prospective basis with retrospective application permitted. Management is currently evaluating ASU 2024-03 to determine its impact on the Company’s disclosures.

Internal-Use Software. In September 2025, the FASB issued ASU 2025-06, Intangibles—Goodwill and Other (Subtopic 350-40) Targeted Improvements to the Accounting for Internal-Use Software (“ASU 2025-06”). This amendment removes references to prescriptive and sequential software development stages, or project stages, and replaces them with a probable-to-complete recognition threshold and also requires disclosures for all capitalized internal-use software costs. ASU 2025-06 is effective for annual reporting periods beginning after December 15, 2027, and interim reporting periods within those reporting periods. The Company is currently evaluating the effect that ASU 2025-06 will have on its consolidated financial statements.

3. REVENUES

Nature of Products and Services. The Company’s Salt segment products include salt and magnesium chloride for use in road deicing and dust control, food processing, water softening, and agricultural and industrial applications. The Company’s plant nutrition segment produces and markets SOP in various grades worldwide to distributors and retailers of crop inputs, as well as growers and for industrial uses. The Company also operates a records management business utilizing excavated areas of its Winsford salt mine with one other location in London, England.

Identifying the Contract. The Company accounts for a customer contract when there is approval and commitment from both parties, the rights of the parties and payment terms are identified, the contract has commercial substance and collectability of consideration is probable.

Identifying the Performance Obligations. At contract inception, the Company assesses the goods and services it has promised to its customers and identifies a performance obligation for each promise to transfer to the customer a distinct good or service (or bundle of goods or services). Determining whether products and services are considered distinct performance obligations that should be accounted for separately or aggregated together may require significant judgment.

Identifying and Allocating the Transaction Price. The Company’s revenues are measured based on consideration specified in the customer contract, net of any sales incentives and amounts collected on behalf of third parties such as sales taxes. In certain cases, the Company’s customer contracts may include promises to transfer multiple products and services to a customer. For multiple-element arrangements, the Company generally allocates the transaction price to each performance obligation in proportion to its stand-alone selling price.

When Performance Obligations Are Satisfied. The vast majority of the Company’s revenues are recognized at a point in time when the performance obligations are satisfied based upon transfer of control of the product or service to a customer. To determine when the control of goods is transferred, the Company typically assesses, among other things, the shipping terms of the contract, as shipping is an indicator of transfer of control. The vast majority of the Company’s products are sold when the control of the goods transfers to the customer at the time of shipment. There are also instances when the Company provides shipping services to deliver its products. Shipping and handling costs that occur before the customer obtains control of the goods are deemed to be fulfillment activities and are accounted for as fulfillment costs. The Company has made an accounting policy election to recognize any shipping and handling costs that are incurred after the customer obtains control of the goods as fulfillment costs which are accrued at the time of revenue recognition.

The Company also derived revenue in fiscal 2023 and 2024 from a full-service air base fire retardant contract with the USFS. Full-service air bases include sales from the supply of fire retardant product and related equipment and service for inspection and loading the fire retardant onto aircraft at designated air tanker bases. The revenue derived from the USFS is comprised ofthree performance obligations, namely product sales, providing operations and maintenance personnel services and leasing of specified equipment. For full-service fire-retardant contracts, the Company identifies the fire-retardant product, equipment leases and services as separate units of account. The performance obligation for product sales is satisfied at a point in time when control of the product is transferred onto the aircraft, typically when the product is consumed by the customer. The services and

leases represent “stand-ready obligations” and the revenue is recognized straight-line over the service period, which could be intermittent.

Significant Payment Terms. The customer contract states the final terms of the sale, including the description, quantity and price of each product or service purchased. Payment is typically due in full within 30 days of delivery. The Company does not adjust the consideration for the effects of a significant financing component if the Company expects, at contract inception, that the period between when the good or service is transferred to the customer and when the customer pays for that good or service will be one year or less. Payment terms vary by contract and sales to customers are deemed collectible at the time of sale based on customer history, prior credit checks, and controls around customer credit limits.

Sales and other taxes assessed by a governmental authority that are both imposed on and concurrent with a specific revenue-producing transaction, which are collected by the Company from a customer, are excluded from revenue.

Refunds, Returns and Warranties. The Company’s products are generally not sold with a right of return and the Company does not generally provide credits or incentives, which may be required to be accounted for as variable consideration when estimating the amount of revenue to be recognized. The Company uses historical experience to estimate accruals for refunds due to manufacturing or other defects, which have historically been minimal. Therefore, there is no estimated obligation for returns. Standard terms of delivery are generally included in the Company's contracts of sale, order confirmation documents and invoices. See Note 11. Commitments and Contingencies for information on the October 2024 product recall.

Shipping and Handling. The Company uses the policy election to account for the shipping and handling activities as activities to fulfill the Company’s promise to transfer goods to the customer, rather than as a performance obligation. Accordingly, the costs of the shipping and handling activities are accrued for at the time of shipment.

Deferred Revenue. Deferred revenue represents collections under non-cancellable contracts before the related product or service is transferred to the customer. The portion of deferred revenue that is anticipated to be recognized as revenue during the succeeding twelve-month period is recorded in accrued expenses and other current liabilities on the Consolidated Balance Sheets. Deferred revenue as of September 30, 2025 and September 30, 2024 was approximately $1.6 million and $3.6 million, respectively. Of the total deferred revenues on the Balance Sheet as of September 30, 2024 that were reclassified to revenue as the result of performance obligations being satisfied during the fiscal year ended September 30, 2025 was $2.4 million.

Practical Expedients and Accounting Policy Elections. The Company has elected the following practical expedients and accounting policies not mentioned above: (i) to expense costs to obtain a contract as incurred when the Company expects that the amortization period would have been one year or less, (ii) not to recast revenue for customer contracts that begin and end in the same fiscal period, and (iii) not to assess whether promised goods or services are performance obligations if they are immaterial in the context of the customer contract.

The following table provides the balances of receivables (in millions):

(a)Refer to Note 11. Commitments and Contingencies for additional information.

See Note 12. Operating Segments for disaggregation of sales by segment, type and geographical region.

4. LEASES

The Company enters into leases for warehouses and depots, rail cars, vehicles, mobile equipment, office space and certain other types of property and equipment. The Company determines whether an arrangement is or contains a lease at the inception of the contract. The right-of-use asset and lease liability are recognized based on the present value of the future minimum lease payments over the estimated lease term. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term. The Company estimates its incremental borrowing rate for each lease based upon the estimated lease term, the

type of asset and the location of the leased asset. The most significant judgments in the application of the FASB guidance include whether a contract contains a lease and the lease term.

Leases with an initial term of 12 months or less are not recorded on the Company’s Consolidated Balance Sheets. The Company recognizes lease expense for these short-term leases on a straight-line basis over the lease term. Many of the Company’s leases include one or more options to renew and extend the initial lease term. The exercise of lease renewal options is generally at the Company’s discretion. The lease term includes renewal periods in only those instances in which the Company determines it is reasonably assured of renewal.

The depreciable lives of assets and leasehold improvements are limited by the expected lease term, unless there is a transfer of title or purchase option reasonably certain of exercise. In these instances, the assets are depreciated over the useful life of the asset.

The Company has elected the practical expedient available under the FASB guidance to not separate lease and non-lease components on all of its lease categories. As a result, many of the Company’s leases include variable payments for services (such as handling or storage) or payments based on the usage of the asset. In addition, certain of the Company’s lease agreements include rental payments that are adjusted periodically for inflation. The Company’s lease agreements do not contain any material residual value guarantees or any material restrictive covenants. The Company’s sublease income is immaterial.

On May 20, 2025, the Company purchased equipment previously leased for Fortress for $2.8 million, resulting in the termination of the related lease. The Company derecognized the right-of-use asset and lease liability. The carrying value of the lease liability was $1.5 million and the right-of-use asset was $1.4 million at the date of purchase. The $1.3 million difference between the purchase price and the lease liability was recorded as an adjustment to the carrying amount of the purchased equipment. Substantially all of the equipment, with a carrying value of $2.7 million included in Property, plant and equipment, net, (“PP&E”) on the Consolidated Balance Sheets, was subsequently disposed of during the fiscal year ended September 30, 2025.

The Company’s Consolidated Balance Sheets includes the following (in millions):

The Company’s components of lease cost are as follows (in millions):

(a)Short-term leases are immaterial and included in variable lease cost.

Minimum annual payments required under existing operating and finance leases and the net present value thereof as of September 30, 2025 (in millions):

Supplemental lease term and discount rate information related to leases is as follows:

Supplemental cash flow information related to leases is as follows (in millions):

5. INVENTORIES

Inventories consist of the following (in millions):

(a)Excludes certain raw materials and supplies of $33.0 million and $42.2 million as of September 30, 2025 and September 30, 2024, respectively, that are not expected to be consumed within the next twelve months, which are included in Other noncurrent assets in the Consolidated Balance Sheets.

6. PROPERTY, PLANT AND EQUIPMENT

Property, plant and equipment consists of the following (in millions):

(a) Includes finance lease right-of-use assets. See Note 4. Leases for further information.

Depreciation and depletion expense was $95.1 million, $97.9 million, and $94.4 million for the fiscal years ended September 30, 2025, September 30, 2024, and September 30, 2023, respectively. For the fiscal year ended September 30, 2025, the net change to property, plant and equipment through accounts payable and accrued expenses and other current liabilities was a reduction of $4.0 million, representing non-cash investing activities within the Consolidated Statements of Cash Flows. In addition, the Company transferred $6.9 million of spare parts inventory to property, plant and equipment, representing non-cash investing activities within the Consolidated Statements of Cash Flows, for the fiscal year ended September 30, 2025.

On May 30, 2025, the Company sold Fortress long-lived assets with a net book value of approximately $15.0 million. See Note 1. Organization and Formation for further information regarding the Asset Purchase Agreement.

During the fiscal year ended September 30, 2025, the Company recorded a loss on impairment of Fortress long-lived assets of $0.7 million, which were included in the Corporate and Other segment. During the fiscal year ended September 30, 2024, the Company recorded a loss on impairment of Lithium long-lived assets of $74.8 million, which were included in the Corporate and Other segment. See Note 2. Summary of Significant Accounting Policies and Note 15. Fair Value Measurements for further information.

7. GOODWILL AND OTHER INTANGIBLE ASSETS

Changes in the carrying amount of goodwill are summarized as follows (in millions):

(a)As of September 30, 2023, there wereno accumulative impairment losses recorded.

(b)As of September 30, 2025, the Salt, Plant Nutrition, and Corporate & Other goodwill is presented net of accumulated impairment losses of $0, $51.0 million, and $32.0 million, respectively.

In the second quarter of fiscal 2024, there were indicators necessitating an interim impairment test of the Company’s goodwill based on the Company’s review of its operating performance, among other factors, for the relevant reporting units. As a result the Company recorded goodwill impairment losses related to the Plant Nutrition reporting unit and the Fortress reporting unit (included in the Corporate and Other segment) of $51.0 million and $32.0 million, respectively. See Note 2. Summary of Significant Accounting Policies and Note 15. Fair Value Measurements for additional details.

The details of definite and indefinite-lived intangible assets are as follows (in millions):

(a) See Note 1. Organization and Formation for information on the Asset Purchase Agreement, which included the sale of the Fortress in-process research and development intangible asset, during the fiscal year ended September 30, 2025.

Aggregate amortization expense was $2.8 million, $4.3 million and $2.7 million for the fiscal years ended September 30, 2025, September 30, 2024, and September 30, 2023, respectively.

The Company recorded a loss on impairment of $53.0 million, related to Fortress customer relationships and trade name definite-lived intangible assets (included in the Corporate and Other segment) of $52.9 million and $0.1 million, respectively, during the fiscal year ended September 30, 2025. During the fiscal year ended September 30, 2024, the Company recorded a loss on impairment of definite-lived intangible assets related to the Company’s developed technology intangible asset of $15.6 million, included in Corporate and Other segment, and a loss on impairment of indefinite-lived intangible assets related to water

rights of $17.6 million included in the Plant Nutrition segment. See Note 2. Summary of Significant Accounting Policies and Note 15. Fair Value Measurements for further information.

Estimated annual amortization for the next five fiscal years for intangible assets is projected below (in millions):

8. INCOME TAXES

The Company files tax returns in the U.S., Canada, the UK and Brazil at the federal and local taxing jurisdictional levels. The Company’s U.S. federal tax returns for tax years 2017 forward remain open and subject to examination. Generally, the Company’s state, local and foreign tax returns for years as early as 2002 forward remain open and subject to examination, depending on the jurisdiction.

The following table summarizes the Company’s income tax provision (in millions):

The following table summarizes components of (loss) income before income taxes and shows the tax effects of significant adjustments from the expected income tax expense computed at the federal statutory rate (in millions):

Under U.S. GAAP, deferred tax assets and liabilities are recognized for the estimated future tax effects, based on enacted tax law, of temporary differences between the values of assets and liabilities recorded for financial reporting and tax purposes, and of net operating losses and other carryforwards. The significant components of the Company’s deferred tax assets and liabilities were as follows (in millions):

At September 30, 2025 and September 30, 2024, the Company had $80.5 million and $76.4 million, respectively, of gross federal net operating loss (“NOL”) carryforwards that have no expiration date and $7.1 million and $6.1 million, respectively, of net operating tax-effected state NOL carryforwards which will expire beginning in 2031. At September 30, 2025 and September 30, 2024, the Company also had $1.9 million and $2.0 million, respectively, of tax-effected state capital losses which will expire beginning in 2027 and $1.6 million and $1.6 million, respectively, of tax-effected federal capital losses, which will expire beginning in 2025.

The Company has recorded a valuation allowance for a portion of its deferred tax asset relating to various tax attributes that it does not believe are more likely than not to be realized. As of September 30, 2025 and September 30, 2024, the Company’s valuation allowance was $198.9 million and $167.3 million, respectively. Management assesses the available positive and negative evidence to estimate whether sufficient future taxable income will be generated to permit use of the existing deferred tax assets. A significant piece of objective negative evidence evaluated was the cumulative loss incurred in the U.S. over the three-year period ended September 30, 2025. Such objective evidence limits the ability to consider other subjective evidence, such as management’s projections for future income. On the basis of this evaluation, for the fiscal year ended September 30, 2025, an additional valuation allowance of $33.1 million has been recorded to recognize only the portion of the U.S. deferred tax assets that are more likely than not to be realized. The amount of the deferred tax assets considered realizable, however, could be adjusted if objective negative evidence in the form of cumulative losses is no longer present and additional weight is given to subjective evidence such as management’s projections for income. In the future, if the Company determines, based on existence of sufficient evidence, that it should realize more or less of its deferred tax assets, an adjustment to the valuation allowance will be made in the period such a determination is made.

The calculation of the Company’s tax liabilities involves dealing with uncertainties in the application of complex tax regulations in multiple jurisdictions. The Company recognizes potential liabilities for unrecognized tax benefits in the U.S. and other tax jurisdictions in accordance with applicable U.S. GAAP, which requires uncertain tax positions to be recognized only if they are more likely than not to be upheld based on their technical merits. The measurement of the uncertain tax position is based on the largest benefit amount that is more likely than not (determined on a cumulative probability basis) to be realized upon settlement of the matter. If payment of these amounts ultimately proves to be unnecessary, the reversal of the liabilities would result in tax benefits being recognized in the period when the Company determines the liabilities are no longer necessary. If the Company’s estimate of tax liabilities proves to be less than the ultimate assessment, a further charge to expense may result.

The Company’s uncertain tax positions primarily relate to transactions and deductions involving U.S. and Canadian operations. If favorably resolved, a maximum of $27.9 million of unrecognized tax benefits would decrease the Company’s effective tax rate. Management believes that it is reasonably possible that $23.6 million of the unrecognized tax benefits will decrease in the next twelve months. For the fiscal year ended September 30, 2025, the Company’s income tax expense included a benefit of approximately $0.1 million related to the release of uncertain tax positions due to the expiration of statutes of limitations.

The following table shows a reconciliation of the beginning and ending amount of unrecognized tax benefits (in millions):

The Company accrues interest and penalties related to its uncertain tax positions within its tax provision. During the fiscal years ended September 30, 2025, September 30, 2024, and September 30, 2023, the Company accrued interest and penalties, net of reversals, of $4.2 million, $5.1 million and $(3.0) million, respectively. As of September 30, 2025 and September 30, 2024, accrued interest and penalties included in Other noncurrent liabilities in the Consolidated Balance Sheets totaled $32.0 million and $27.8 million, respectively.

In fiscal 2022, the Company revised its permanently reinvested assertion, expecting to repatriate an additional $10 million of unremitted foreign earnings from its UK operations and in fiscal 2023 the Company revised it again expecting to repatriate an additional approximately $6 million of unremitted foreign earnings from its UK operations. During the first quarter of fiscal 2023, $89.2 million was repatriated from Canada and in the third quarter of fiscal 2023, $15.6 million was repatriated from the UK. Net income tax expense of $3.8 million has been recorded for foreign withholding tax, state income tax and foreign exchange losses on these changes in assertion as of September 30, 2025, consisting of a tax benefit of $0.0 million recorded during fiscal year ended September 30, 2025, a $0.0 million tax benefit recorded during fiscal year ended September 30, 2024, and a $0.7 million tax benefit recorded in fiscal year ended September 30, 2023. The Company intends to continue its permanently reinvested assertion on the remaining undistributed earnings of its foreign subsidiaries indefinitely. As of September 30, 2025, the Company has approximately $242.8 million of outside basis differences on which no deferred taxes have been recorded as the determination of the unrecognized deferred taxes is not practicable.

A Canadian provincial tax authority has challenged tax positions claimed by one of the Company’s Canadian subsidiaries and have issued tax reassessments for fiscal years 2002-2019. The reassessments are a result of ongoing audits and total approximately $209.8 million, including interest, through September 30, 2025. The Company disputes these reassessments and plans to continue to work with the appropriate authorities in Canada to resolve the dispute. In connection with this dispute, local regulations require the Company to post security with the tax authority until the dispute is resolved. The Company has posted collateral in the form of a $157.4 million performance bond and has paid $35.8 million (most of which is recorded in other assets in the Consolidated Balance Sheets at September 30, 2025), which was required to pursue appeals or litigation.

The Company expects that the ultimate outcome of these matters will not have a material impact on its results of operations or financial condition. As of September 30, 2025, the Company believes it has adequately reserved for these reassessments.

See Note 18. Subsequent Event for information concerning the settlement of Canadian provincial tax disputes for years 2002-2018.

Additionally, the Company has other uncertain tax positions as well as assessments and disputed positions with taxing authorities in its various jurisdictions.

9. PENSION PLANS AND OTHER BENEFITS

UK Pension

The Company has a defined benefit pension plan for certain of its former UK employees. Benefits of this pension plan are based on a combination of years of service and compensation levels. This plan was closed to new participants in 1992. Beginning December 1, 2008, future benefits ceased to accrue for the remaining active employee participants in the pension plan concurrent with the establishment of a defined contribution plan for these employees.

The following table sets forth pension obligations and plan assets for the Company’s UK pension plan (in millions):

The Company’s UK pension plan was overfunded as of September 30, 2025 and September 30, 2024, and accordingly, $1.2 million and $2.2 million has been recorded as a noncurrent asset, respectively, in the Company’s Consolidated Balance Sheets. The accumulated benefit obligation for the UK pension plan was $42.0 million and $45.0 million as of September 30, 2025 and September 30, 2024, respectively. The plan assets were in excess of the accumulated benefit obligation as of September 30, 2025 and September 30, 2024. The vested benefit obligation is the actuarial present value of the vested benefits to which the employee is currently entitled but based on the employee’s expected date of retirement. Since all employees are vested, the accumulated benefit obligation and the vested benefit obligation are the same amount.

The Company uses a straight-line methodology of amortization subject to a corridor based upon the higher of the fair value of assets and the pension benefit obligation over afive-year period. The components of net periodic pension cost (benefit) were as follows (in millions):

The following table summarizes changes in other comprehensive loss (income) (in millions):

Amounts recognized in accumulated other comprehensive loss, net of tax, consisted of the following (in millions):

Amounts in accumulated other comprehensive loss expected to be recognized in components of net periodic pension cost during the fiscal year ended September 30, 2026 (in millions):

The assumption used to determine benefit obligations for the UK pension plan was as follows:

The assumptions used to determine net periodic benefit costs for the UK pension plan were as follows:

The Company’s UK pension plan investment strategy is to maximize return on investments while minimizing risk. This is accomplished by investing in high-grade equity and debt securities. The Company’s portfolio guidelines recommend that equity securities comprise approximately 30% of the total portfolio and that approximately 70% be invested in debt securities. The Company attempts to follow strategies that will reduce volatility, while also maximizing returns. Investment strategies and portfolio allocations are based on the UK pension plan’s benefit obligations and its funded or underfunded status, expected returns, and the Company’s portfolio guidelines and are monitored on a regular basis. The weighted-average asset allocations by asset category are as follows:

The fair value of the Company’s UK pension plan assets by asset category (see Note 15. Fair Value Measurements for a discussion regarding fair value measurements) are as follows (in millions):

(a)The fair value of cash and cash equivalents is its carrying value.

(b)The Company is invested in a diversified growth fund. The diversified growth fund is valued at the last traded or official close for the underlying equities and bid or mid for the underlying fixed income securities depending on the portfolio benchmark. Where representative prices are unavailable, underlying fixed income investments are valued based on other observable market-based inputs.

(c)This category includes investments in investment-grade fixed-income instruments and funds linked to UK treasury notes. The funds are valued using the bid amounts for each fund. The Company’s bond fund pension assets are primarily invested in UK-linked treasuries.

The overall expected long-term rate of return on plan assets is a weighted-average expectation based on the fair value of targeted and expected portfolio composition. The Company considers historical performance and current benchmarks to arrive at expected long-term rates of return in each asset category. The Company determines its discount rate based on a forward yield curve for a portfolio of high-credit-quality bonds with expected cash flows and an average duration closely matching the expected benefit payments under the plan.

The Company’s funding policy is to make the minimum annual contributions required by applicable regulations or agreements with the plan administrator. Management expects there will be no contributions during 2026. In addition, the Company may periodically make contributions to the plan based upon the underfunded status of the plan or other transactions, which warrant incremental contributions in the judgment of management.

The UK pension plan includes a provision whereby supplemental benefits may be available to participants under certain circumstances after case review and approval by the plan trustees. Because instances of this type of benefit have historically been infrequent, the development of the projected benefit obligation and net periodic pension cost (benefit) has not provided for any future supplemental benefits. If additional benefits are approved by the trustees, it is likely that an additional contribution would be required and the amount of incremental benefits would be expensed by the Company.

The Company expects to pay the following benefit payments (in millions):

Other Post-Employment Benefits

The Company provides retirement medical, dental and life insurance benefits and post-employment vacation benefits to certain Canadian employees (collectively, the “Canadian Benefits”), which are considered other post-employment benefit obligations.

The assumed discount rate used to determine the benefit obligation for the Canadian Benefits as of September 30, 2025 and September 30, 2024 was 4.80% and 4.60%, respectively. The ultimate trend rate used to determine the benefit obligation for the Canadian Benefits as of September 30, 2025 and September 30, 2024 was 4.00%. The year that the rate reaches the ultimate trend rate is 2040.

The Company expects to pay the following payments for the Canadian Benefits (in millions):

The following table sets forth the Company’s benefit obligation (in millions):

The Company uses the Projected Unit Credit Method in determining its benefit obligation. Under this method, each participant’s benefits are attributed to years of service, taking into account the projection of benefit costs. The components of net periodic cost (benefit) are also shown above.

Other

The Company has defined contribution and pre-tax savings plans (the “Savings Plans”) for certain of its employees. Under each of the Savings Plans, participants are permitted to defer a portion of their compensation. Company matching contributions to the Savings Plans are based on a percentage of employee contributions. Additionally, certain of the Savings Plans have a profit-sharing feature for salaried and non-union hourly employees. The Company contribution to the profit-sharing feature is discretionary and based on the Company’s financial performance and other factors.

The Savings Plans include a non-qualified deferred compensation plan for certain executive officers and other key employees who are limited in their ability to participate in qualified plans due to existing regulations. These employees are allowed to defer a portion of their compensation, upon which they will be entitled to receive Company contributions despite the limitations imposed by current U.S. regulations for qualified plans. The Company’s contributions to the Savings Plans include Company matching contributions based on a percentage of the employee’s deferred salary, discretionary profit sharing contributions and any investment income (loss) that would have been credited to their account had the contributions been made according to employee-designated investment specifications. Although not required to do so, the Company invests amounts equal to the salary deferrals, the corresponding Company matching contribution and discretionary profit sharing amounts according to the employee-designated investment specifications. As of September 30, 2025 and September 30, 2024, investments in marketable securities totaling $3.5 million and $3.1 million, respectively, were included in other noncurrent assets with a corresponding deferred compensation liability included in other noncurrent liabilities in the Consolidated Balance Sheets. Compensation expense recorded for the non-qualified plan was immaterial for each of the fiscal years ended September 30, 2025, September 30, 2024, and September 30, 2023, including amounts attributable to investment income, and was included in other, net in the Consolidated Statements of Operations.

Expense attributable to the Savings Plans was $9.8 million, $12.1 million and $10.7 million for the fiscal years ended September 30, 2025, September 30, 2024, and September 30, 2023, respectively.

10. LONG TERM DEBT AND FINANCE LEASE LIABILITIES

Total long-term carrying value of debt and finance lease liabilities consists of the following (in millions):

8.00% Senior Notes due 2030

On June 16, 2025, the Company issued $650.0 million aggregate principal amount of its 8.00% Senior Notes due 2030 in a private offering, pursuant to an indenture, dated June 16, 2025 (the “2030 Notes”), among the Company, the subsidiary guarantors named therein and Computershare Trust Company, N.A., as trustee. The 2030 Notes are senior unsecured obligations, with interest payable semi-annually on January 1 and July 1, commencing January 1, 2026. The Notes are guaranteed by certain of the Company’s domestic subsidiaries. The 2030 Notes will mature on June 16, 2030. The Company incurred $13.0 million in deferred financing costs, including arrangement, legal and other fees, and will be amortized to interest expense over the 5-year term of the 2030 Notes.

The Company used the net proceeds from the 2030 Notes to (i) repay all outstanding amounts under its senior secured credit facility, including $43.5 million under the revolving credit facility and $191.3 million under the term loan, (ii) redeem $350.0 million of its outstanding 6.75% Senior Notes due 2027 (the “2027 Notes”) at a redemption price of 101.125% of the principal amount, plus accrued and unpaid interest, (iii) pay transaction-related fees and expenses, (iv) increase cash on its balance sheet, and (v) for general corporate purposes.

Prior to July 1, 2027, the Company may redeem some or all of the 2030 Notes up to 40.0% of the aggregate principal amount with equity offering proceeds at a redemption price equal to 108.0% of the principal amount, plus accrued and unpaid interest, subject to certain conditions. On or after July 1, 2027, the Company may redeem some or all of the 2030 Notes at 104.0% of the principal amount thereof, declining ratably to 100.0% of the principal amount thereof on or after July 1, 2029, plus accrued and unpaid interest to the redemption date.

The indenture governing the 2030 Notes contains covenants limiting other indebtedness, dividends, purchases or redemptions of stock, transactions with affiliates, and mergers and sales of assets.

Amended and Restated Credit Agreement

On June 16, 2025, the Company entered into the fifth amendment to its 2023 Credit Agreement, as of April 20, 2016, as amended and restated as of November 26, 2019 (the “Amended and Restated 2023 Credit Agreement”). The amendment, among other things, (i) fixed the aggregate revolving commitments at $325.0 million, eliminating the automatic periodic step-downs previously included in the December 12, 2024 amendment to the 2023 Credit Agreement, which had scheduled reductions to $250.0 million by July 1, 2026, (ii) permitted the issuance of the 2030 Notes, with net proceeds used to prepay all outstanding loans under the Existing Amended and Restated Credit Agreement, including $43.5 million outstanding under the revolving credit facility and $191.3 million outstanding under the term loan, plus accrued and unpaid interest, (iii) permitted the

Company to utilize certain baskets under covenants restricting the incurrence of indebtedness, liens, investments, dividends, and junior debt prepayments, and (iv) modified the financial maintenance covenants, which are tested on a quarterly basis, as follows: (A) replaced the leverage-based covenant, which previously required compliance with a maximum ratio of consolidated total net indebtedness to a consolidated EBITDA of 6.50 x (with a step-down to 5.75 x on December 31, 2025, and a further step-down to 4.75 x on March 31, 2026) with a leverage-based covenant which requires compliance with a maximum ratio of consolidated first lien net indebtedness to consolidated EBITDA of 2.75 x (with a step-down to 2.50 x on December 31, 2025) and (B) lowered the required minimum ratio of consolidated EBITDA to consolidated interest expense from 2.00 x (with a step-up to 2.25 x on March 31, 2026) to 1.50 x. Consolidated first lien net debt includes the aggregate principal amount of consolidated first lien debt, net of unrestricted cash not to exceed $100.0 million. In connection with the prepayment of the term loan, the Company recorded a loss on debt extinguishment of $1.9 million, included in Loss on extinguishment of debt in the Consolidated Statements of Operation for the fiscal year ended September 30, 2025, related to the write-off of unamortized deferred financing costs relating to this instrument.

The revolving credit facility under the Amended and Restated 2023 Credit Agreement is secured by substantially all existing and future U.S. assets of the Company, the Goderich mine in Ontario, Canada, and capital stock of certain subsidiaries. Borrowings, if any, accrue interest at a rate per annum based on, at the Company’s option, the Adjusted Term SOFR Rate, Adjusted EURIBO Rate, Canadian Prime Rate, or Sterling Overnight Index Average, adjusted for applicable margins and floors. As of September 30, 2025, no borrowings were outstanding under the revolving credit facility. Also, as of September 30, 2025, outstanding letters of credit totaling $20.1 million reduced available borrowing capacity to $304.9 million.

The Amended and Restated 2023 Credit Agreement contains covenants that limit the Company’s ability, among other things, to incur additional indebtedness or contingent obligations or grant liens; pay dividends or make distributions to stockholders; repurchase or redeem the Company’s stock; make investments or dispose of assets; prepay, or amend the terms of certain junior indebtedness; engage in sale and leaseback transactions; make changes to the Company’s organizational documents or fiscal periods; grant liens on the Company’s assets or make certain intercompany dividends, investments or asset transfers; enter into new lines of business; enter into transactions with the Company’s stockholders and affiliates; and acquire the assets of or merge or consolidate with other companies.

As of September 30, 2025, there wereno borrowings under the term loan and revolving credit facility. As of September 30, 2024, the weighted average interest rate was 7.6% on all borrowings outstanding under the 2023 Credit Agreement. Depending on the type, borrowings under the 2023 Credit Agreement accrue interest at a rate per annum equal to the Adjusted Term SOFR Rate, the Adjusted EURIBO Rate, Prime Rate or the CDO Rate (as defined in the credit agreement), as applicable, plus Applicable Margins (as defined in the credit agreement) which resulted in interest rates between 7.3% and 9.5% as of September 30, 2024. As of September 30, 2024, the term loan and revolving credit facility under the 2023 Credit Agreement were secured by substantially all existing and future U.S. assets of the Company, the Goderich mine in Ontario, Canada, and capital stock of certain subsidiaries.

Prior Amendments to the Credit Agreement

On December 12, 2024, the Company entered into a fourth amendment to its 2023 Credit Agreement as of April 20, 2016, as amended and restated as of November 26, 2019, which, among other things, eased the restrictions of certain covenants contained in the agreement. The amendment included increasing the maximum allowed consolidated total net leverage ratio (as defined and calculated under the terms of the amended 2023 Credit Agreement) to 6.5 x as of the last day of any quarter through the fiscal quarter ended September 30, 2025, then gradually stepping down to 4.5 x for the fiscal quarter ended December 31, 2026 and thereafter. The amendment also decreased the Revolving Commitments (as defined in the Existing Credit Agreement) from $375 million to $325 million with additional reductions stepping down to $250 million on July 1, 2026. In connection with the 2023 Credit Agreement, the Company paid $4.3 million in fees ($3.9 million was capitalized as deferred financing costs with $0.4 million recorded as an expense). These capitalized costs are amortized over the term of the debt and are included as a component of interest expense in the Consolidated Statements of Operations. The Company incurred a loss on the extinguishment of debt of $1.0 million to write off previously capitalized deferred financing costs, which is included as a component of Other expense, net in the Consolidated Statements of Operations.

On September 13, 2024, the Company entered into a third amendment to its 2023 Credit Agreement as of April 20, 2016, as amended and restated as of November 26, 2019, which extended the deadline for delivery of the Company’s financial statements for the quarter ended June 30, 2024 (the “Q3 2024 Form 10-Q”), together with the respective compliance certificates, to November 29, 2024,152 days after the last day of the quarter ended June 30, 2024.

On August 12, 2024, the Company entered into the second amendment to its 2023 Credit Agreement as of April 20, 2016, as amended and restated as of November 26, 2019, which extended the deadline for delivery of the Company’s financial statements for the quarter ended June 30, 2024, together with the respective compliance certificates, from 45 days to 75 days after the last day of the quarter ended June 30, 2024.

On March 27, 2024, the Company entered into the first amendment to its 2023 Credit Agreement as of April 20, 2016, as amended and restated as of November 26, 2019, which eased the restrictions of certain covenants contained in the agreement. The amendment included increasing the maximum allowed consolidated total net leverage ratio (as defined and calculated under the terms of the amended 2023 Credit Agreement) to 6.5 x as of the last day of any quarter through the fiscal quarter ended December 31, 2024, then gradually stepping down to 4.75 x by the fiscal quarter ended March 31, 2026 and thereafter. In connection with this amendment, the Company paid fees totaling $1.7 million which were capitalized as deferred financing costs. Additional arrangement and legal fees of $0.9 million were expensed.

On May 5, 2023, the Company entered into an agreement to amend and restate the Company’s credit agreement entered into on November 26, 2019 (as amended, the “2019 Credit Agreement”, as in effect prior to such restatement, the “Existing Credit Agreement”) with a then new $575 million senior secured credit agreement due May 5, 2028 (as amended, the “2023 Credit Agreement”), comprised of a $375 million revolving credit facility and a $200 million term loan. The term loan was payable in quarterly installments of interest and principal, which began September 30, 2023. The 2023 Credit Agreement increased the Applicable Margins by 25 basis points over those defined in the Existing Credit Agreement and added an additional level to the pricing grid at a consolidated total leverage ratio of greater than 4:00 to 1.00.

The 2023 Credit Agreement, among other things, amended and restated the Existing Credit Agreement to (i) increase the Revolving Commitments (as defined in the Existing Credit Agreement) from $300 million to $375 million and extend the maturity date of the Revolving Commitments to May 5, 2028, (ii) refinance the Term Loans (as defined in the Existing Credit Agreement) with a new tranche of term loans in an aggregate principal amount equal to $200 million having a maturity date of May 5, 2028, and (iii) amend certain other terms of the Existing Credit Agreement, including, but not limited to, (a) expressly permit “run rate” cost savings in “Consolidated Adjusted EBITDA” (as defined in the Existing Credit Agreement) and (b) revise select covenants in the Existing Credit Agreement.

6.75% Senior Notes due 2027

In November 2019, the Company issued $500 million 6.75% Senior Notes due December 2027 (the “2027 Notes”), which are subordinate to the 2023 Credit Agreement borrowings. The 2027 Notes are unsecured obligations and are guaranteed by certain of the Company’s domestic subsidiaries. Interest on the 2027 Notes is due semi-annually in June and December. The 2027 Notes are subordinated to all existing and future indebtedness. In connection with the 2027 Notes, the Company paid fees of $8.2 million, which were capitalized as deferred financing costs.

On September 18, 2024, the Company received a notice of default relating to its 2027 Notes because the Company failed to timely furnish a Quarterly Report on Form 10-Q for the Q3 2024 Form 10-Q. The Company had 90 days from receipt of the notice to remedy prior to it becoming an Event of Default under the terms of the Indenture, dated November 26, 2019. The Company’s Q3 Form 10-Q was filed with the SEC on October 30, 2024.

On June 17, 2025, $350.0 million of the 2027 Notes were redeemed, which resulted in a loss on debt extinguishment of $5.7 million, included in Loss on extinguishment of debt in the Consolidated Statements of Operation for the fiscal year ended September 30, 2025. The loss was comprised of a $3.9 million prepayment premium and a $1.8 million write-off of unamortized deferred financing costs. Following the redemption, $150.0 million of the 2027 Notes remain outstanding and continue to accrue interest, payable semi-annually on June 1 and December 1, with unamortized deferred financing costs of $0.7 million as of September 30, 2025.

The indenture governing the 2027 Notes contains covenants limiting other indebtedness, dividends, purchases or redemptions of stock, transactions with affiliates, and mergers and sales of assets.

AR Securitization Facility

On June 30, 2020, certain of the Company’s U.S. subsidiaries entered into athree-year committed revolving accounts receivable financing facility (the “AR Facility”) of up to $100.0 million with PNC Bank, National Association (“PNC”), as administrative agent and lender, and PNC Capital Markets, LLC, as structuring agent. On June 27, 2022, certain of the Company’s U.S. subsidiaries entered into a first amendment to the AR Facility, extending the facility to June 2025. In January 2023, certain of the Company’s U.S. subsidiaries entered into the second amendment to the AR Facility with PNC Bank, which temporarily eased the restrictions of certain covenants contained in the agreement through March 2023. The amendment made certain adjustments to the financial tests including: (i) the default ratio and (ii) the delinquency ratio to make compliance with such tests more likely.

On March 27, 2024, certain of the Company’s U.S. subsidiaries entered into a third amendment to its revolving accounts receivable financing facility with PNC, extending the facility to March 2027. In connection with this amendment, the Company paid fees totaling $0.4 million which were capitalized as deferred financing costs.

On August 12, 2024, the Company entered into a fourth amendment to its AR Facility, which extended the deadline for delivery of the Company’s Q3 2024 Form 10-Q, together with the respective compliance certificates, from 45 days to 75 days after the last day of the quarter ended June 30, 2024.

On September 13, 2024, the Company entered into a fifth amendment to its AR Facility, which extended the deadline for delivery of the Company’s Q3 2024 Form 10-Q, together with the respective compliance certificates, to November 29, 2024,152 days after the last day of the quarter ended June 30, 2024. The Company’s Q3 2024 Form 10-Q was filed with the SEC on October 30, 2024.

In connection with the AR Facility, one of the Company’s U.S. subsidiaries, from time to time, sells and contributes receivables and certain related assets to a special purposes entity and wholly-owned U.S. subsidiary of the Company (the “SPE”). The SPE finances its acquisition of the receivables by obtaining secured loans from PNC and the other lenders party to a receivables financing agreement. A U.S. subsidiary of the Company services the receivables on behalf of the SPE for a fee. In addition, the Company has agreed to guarantee the performance by its subsidiaries. The Company and its subsidiaries do not guarantee the loan principal or interest under the receivables financing agreement or the collectability of the receivables under the AR Facility.

The purchase price for the sale of receivables consists of cash available to the SPE from loans under the AR Facility and from collections on previously sold receivables and, to the extent the SPE does not have funds available to pay the purchase price due on any day in cash, through an increase in the principal amount of a subordinated intercompany loan. The SPE pays monthly interest and fees with respect to amounts advanced by the lenders under the AR Facility.

The SPE’s sole business consists of the purchase or acceptance through capital contributions of the receivables and the subsequent granting of a security interest in these receivables and related rights to PNC on behalf of the lenders under the AR Facility. The SPE is a separate legal entity with its own separate creditors who will be entitled, upon its liquidation, to be satisfied out of the SPE’s assets prior to any assets or value in the SPE becoming available to the Company and the assets of the SPE are not available to pay creditors of the Company or any of its affiliates other than the SPE. The Company accounts for the securitization as a borrowing and the related receivables are included in the accounts receivable balance.

Covenant Compliance and Other Information

The Amended and Restated 2023 Credit Agreement requires compliance with certain financial covenants, including a maximum Consolidated First Lien Net Leverage Ratio and minimum Consolidated Interest Coverage Ratio, tested quarterly. As of September 30, 2025, the Company was in compliance with these covenants.

Future maturities of long-term debt are as follows (in millions):

11. COMMITMENTS AND CONTINGENCIES

Contingent Obligations

The Company is subject to legal and administrative proceedings and claims of various types from the ordinary course of the Company’s business. If management believes that a loss arising from these actions is probable and can reasonably be estimated, the Company records the amount of the loss or the minimum estimated liability when the loss is estimated using a range and no point is more probable than another. As additional information becomes available, any potential liability related to these actions is assessed and the estimates are revised, if necessary.

Management cannot predict the outcome of legal claims and proceedings with certainty. Nevertheless, management believes that the outcome of legal proceedings and claims, which are pending or known to be threatened, even if determined adversely, will not, individually or in the aggregate, have a material adverse effect on the Company’s results of operations, cash flows or financial position given current insurance coverage, except as otherwise described in Note 8. Income Taxes and this Note 11.

On October 21, 2022, a putative securities class action was filed in the United States District Court for the District of Kansas. The lawsuit alleges that the Company and certain former executives of the Company made misleading statements and that shareholders were damaged by these statements. Plaintiffs filed an Amended Complaint on March 13, 2023. On February 7, 2025, the parties reached an agreement in principle to resolve the matter. On March 27, 2025, the parties entered into a Joint Stipulation of Settlement. A motion for final approval of the settlement was filed with the court on June 25, 2025. On July 30, 2025, the court held a hearing at which it approved the settlement of $48.0 million, including fees and expenses awarded to lead counsel and plaintiffs. The Company’s insurers have consented to and funded the agreed upon settlement, and therefore, the Company does not have either a liability or corresponding insurance recoveries, included in Receivables, in its Consolidated Balance Sheets as of September 30, 2025.

On February 1, 2023, a shareholder derivative lawsuit was filed in the District of Kansas by an individual shareholder, purportedly on behalf of the Company. The lawsuit alleges that certain directors and executives breached their fiduciary duties to shareholders by failing to prevent the dissemination of misstatements and omissions from October 30, 2017 to November 18, 2018. On October 30, 2024, an additional shareholder derivative lawsuit was filed in the District of Kansas by an individual shareholder, purportedly on behalf of the Company. The lawsuit alleges that certain directors and executives breached their fiduciary duties to shareholders by willfully or recklessly causing the Company to make false and/or misleading statements and/or omissions of material fact from October 31, 2017 to October 21, 2022. On February 28, 2025, this matter was consolidated with the derivative matter filed on February 1, 2023. On May 27, 2025, the parties reached an agreement in principle to resolve the consolidated derivative lawsuit in exchange for the Company’s agreement to adopt certain corporate governance reforms. A motion for final approval of the settlement was filed with the court on September 2, 2025. On October 14, 2025, the court held a hearing at which it approved the settlement, including fees and expenses awarded to lead counsel and plaintiffs. Insurers for the defendant directors and executives thereafter made their respective payments for the full amount of the awarded fees and expenses pursuant to their commitments and in accordance with the court’s order and the settlement agreement.

On April 24, 2024, a putative securities class action was filed in the United States District Court for the District of Kansas. The complaint alleges that the Company and certain individuals made materially false and misleading statements regarding Fortress North America and that shareholders were damaged by these statements. On December 12, 2024, the court appointed lead plaintiff and counsel. Plaintiffs filed an Amended Complaint on February 10, 2025. The parties have executed a settlement agreement dated June 30, 2025, to resolve the matter, which settlement has been consented to by the Company’s insurers. The

court granted preliminary approval of the settlement on July 25, 2025 and a hearing is scheduled for January 7, 2026, for the court to consider any objections and to make a determination regarding final approval of the settlement.

On October 30, 2024, a shareholder derivative lawsuit was brought against certain current and former officers and directors of the Company, purportedly on behalf of the Company. The lawsuit alleges that from November 29, 2023 to March 22, 2024, certain current and former officers and directors willfully or recklessly caused the Company to make false and/or misleading statements and/or omissions of material fact regarding the Company’s fire-retardant business. On April 9, 2025, an additional derivative lawsuit was brought against certain current and former officers and directors of the Company, purportedly on behalf of the Company. The lawsuit alleges that certain current and former officers and directors caused Compass Minerals to make misleading statements regarding the Company’s fire-retardant business. In an order dated June 3, 2025, the court consolidated thetwo derivative actions for the discovery phase of the actions. On July 30, 2025, the plaintiffs in the consolidated derivative action filed a verified amended consolidated shareholder derivative complaint asserting claims that certain statements made between February 8, 2023 until March 25, 2024 about the Company’s fire retardant business were false and/or misleading. The parties have executed a settlement agreement dated October 24, 2025, to resolve the derivative actions, subject to obtaining court approval. Pursuant to the settlement agreement, the Company will implement certain corporate governance reforms as specified therein, and the Company’s insurers have agreed to pay legal fees and expenses to plaintiffs’ counsel. The court granted preliminary approval of the settlement on December 10, 2025, and scheduled a hearing for final approval for February 20, 2026.

On October 25, 2024, the Company issued a recall for specific production lots of food-grade salt produced at its Goderich Plant following a customer report of a non-organic, foreign material in its product. The Company subsequently expanded the voluntary recall to include food products from the Goderich Plant between September 18, 2024 and November 6, 2024. The Company followed recall protocol and notified its BRCGS Global Standard for Food Safety certifying body, the Canadian Food Inspection Agency (“CFIA”) and the U.S. Food and Drug Administration (“FDA”). The Company has completed its investigation and continues to assess the scope and magnitude of asserted and potential customer claims related to the recall. At this time, based on currently available information and its applicable insurance coverage, the Company does not believe any incremental losses will have a material adverse effect on its results of operations or cash flows in future periods. The recall in the United States, supervised by the FDA, is complete, and the matter is closed with FDA. The CFIA has conducted a follow-up inspection of the Goderich Plant to verify compliance with regulatory requirements and identified no non-compliances.

As of September 30, 2025 and September 30, 2024, the Company recorded a liability of $51.8 million and $6.7 million, respectively, included in Accrued expenses and other liabilities, and estimated insurance recoveries of $47.0 million and $6.7 million, respectively, included in Receivables in the Consolidated Balance Sheets associated with the recall matters described above, in addition to all other legal and administrative proceedings.

Nearly 50% of the Company’s workforce is represented by collective bargaining agreements. Of the Company’s 12 collective bargaining agreements in effect on September 30, 2025:

•Six expired in fiscal 2025 (including the Company’s Cote Blanche mine), four of which were renewed/renegotiated andtwo are still in the process of being negotiated;

•Four will expire in fiscal 2026 (including the Company’s Goderich mine, which have 393 positions represented by a CBA); and

Commitments

Royalties. The Company has various private, state and Canadian provincial leases associated with the salt and SOP businesses, most of which are renewable by the Company. Many of these leases provide for a royalty payment to the lessor based on a specific amount per ton of mineral extracted or as a percentage of revenue. Royalty expense related to these leases was $18.2 million, $16.2 million and $18.7 million for the fiscal years ended September 30, 2025, September 30, 2024, and September 30, 2023, respectively.

Performance Bonds. The Company has various salt and other deicing product sales contracts that include performance provisions governing delivery and product quality. These sales contracts either require the Company to maintain performance bonds for stipulated amounts or contain contractual penalty provisions in the event of non-performance. For the fiscal years ended September 30, 2025, September 30, 2024, and September 30, 2023, the Company has had no material penalties related to these sales contracts. At September 30, 2025, the Company had $211.5 million of outstanding performance bonds, which includes bonds related to Ontario mining tax reassessments. See Note 18. Subsequent Event for further information.

Purchase Commitments. In connection with the operations of the Company’s facilities, the Company purchases utilities, other raw materials and services from third parties under contracts extending, in some cases, for multiple years. Purchases under these contracts are generally based on prevailing market prices. The Company has minimum throughput contracts with some of its depots and warehouses. The purchase commitments for these contracts are estimated to be $33.6 million for 2026, $29.8 million in 2027, $11.7 million in 2028, $5.3 million in 2029, and $3.1 million in 2030.

12. OPERATING SEGMENTS

The Company’s reportable segments are strategic business units that offer different products and services, and each business requires different technology and marketing strategies. For all periods presented in this Form 10-K, the Company hastwo reportable segments in its Consolidated Financial Statements: Salt and Plant Nutrition. The Salt segment produces and markets salt, consisting primarily of sodium chloride and magnesium chloride, for use in road deicing for winter roadway safety and for dust control, food processing, water softeners and other consumer, agricultural and industrial applications. The Plant Nutrition segment produces and markets various grades of SOP. The results of operations for the Company’s records management business and former fire retardant business are included in Corporate and Other in the tables below.

The chief operating decision maker (“CODM”) is the Company’s President and Chief Executive Officer. The primary measure of segment profit or loss used by the CODM to regularly evaluate performance, make key operating decisions and determine resource allocation of and among each operating segment is operating income. The CODM assesses segment performance by comparing actual operating income to budgeted and/or forecasted performance, and making decisions such as whether and when to invest resources for future capital expenditures and for general corporate purposes.

Segment operating income is based upon segment sales less expenses attributable to the respective segment. The accounting policies of the segments are the same as those described in the summary of significant accounting policies. All inter-segment sales prices are market-based. The segment operating income also includes the allocable portion of the Company’s Selling, general and administrative expenses, which represents overhead functions such as: finance and accounting, legal, information technology, human resources and other general functions that support the operations of Salt and Plant Nutrition. The unallocated Selling, general and administrative expenses that are not directly attributable to the reportable segments are included in Corporate and Other.

In evaluating segment performance, the CODM regularly reviews several significant segment expenses. For the period’s presented, the significant expenses reviewed by the CODM were Shipping and handling costs, Product costs, Selling, general and administrative expenses, Loss on impairments, and Other operating (income) expense. Other items such as Depreciation, depletion and amortization are also reviewed to provide a comprehensive understanding of segment performance.

Segment information is as follows (in millions):

Disaggregated revenue by product type is as follows (in millions):

(a)Corporate and Other includes corporate entities, records management operations, Fortress, equity method investments, prior year lithium-related costs and other incidental operations and eliminations. Operating income (loss) for corporate and other includes indirect corporate overhead, including costs for general corporate governance and oversight, prior year lithium-related expenses, as well as costs for the human resources, information technology, legal and finance functions.

(b)Sales to external customers are net of intersegment sales.

(c)The Company recorded loss on impairments of $53.7 million and $193.4 million (inclusive of the $2.4 million impairment of Fortress related inventory included in Product costs), for the fiscal years ended September 30, 2025 and September 30, 2024, respectively, which impacted operating results. Refer to Note 2. Summary of Significant Accounting Policies for additional information regarding the loss on impairments of Plant Nutrition, Fortress, and lithium development assets.

(d)Corporate and Other operating results were impacted by net gains of $7.9 million, $22.1 million and $0.8 million, recorded in Other operating (income) expense, related to the decline in the valuation of the Fortress contingent consideration for the fiscal years ended September 30, 2025, September 30, 2024 and September 30, 2023, respectively.

(e)The Company continued to take steps to align its cost structure to its current business needs. These initiatives impacted Corporate and Other operating results and resulted in net severance and related charges, excluding stock-based compensation forfeitures, for reductions in workforce, changes to executive leadership and additional restructuring costs related to the termination of the Company’s lithium development project recorded in Other operating (income) expense of $4.3 million, $15.8 million and $5.5 million for the fiscal years ended September 30, 2025, September 30, 2024 and September 30, 2023, respectively.

Financial information relating to the Company’s operations by geographic area is as follows (in millions):

(a)United States sales exclude product sold to foreign customers at U.S. ports.

Financial information relating to the Company’s long-lived assets, excluding the investments related to the non-qualified retirement plan and pension plan assets, by geographic area (in millions):

13. STOCKHOLDERS’ EQUITY AND EQUITY INSTRUMENTS

The Company paid dividends of $0.30 per share during fiscal year ended September 30, 2024. In April 2024, the Board of Directors determined not to declare dividends for the foreseeable future in order to align the Company’s capital allocation priorities with its corporate focus on accelerating cash flow generation and debt reduction. The declaration and payment of future dividends to holders of the Company’s common stock will be at the discretion of the Company’s Board of Directors and will depend upon many factors, including the Company’s financial condition, earnings, legal requirements, capital allocation strategy, restrictions in its debt agreements and other factors the Company’s Board of Directors deems relevant.

Koch Equity Investment

On September 14, 2022, the Company entered into a Stock Purchase Agreement with Koch Minerals & Trading, LLC (“KM&T”), a subsidiary of Koch, Inc. (“Koch”), pursuant to which the Company agreed to issue and sell 6,830,700 shares of its common stock at a purchase price of $36.87 for aggregate net proceeds of approximately $240.7 million, net of transaction costs. On October 18, 2022, the Company closed the direct private placement with KM&T, through its affiliate KM&T Investment Holdings, LLC, resulting in their ownership of approximately 17% of the Company’s outstanding common stock. The original plan for these proceeds was to use them to advance the first development phase of the lithium project. The Company used approximately $78 million of the proceeds from the private placement for capital expenditures related to the lithium project before the project was terminated. The balance of the proceeds were used to reduce debt or for general corporate purposes. The shares issued and sold to KM&T were registered via a resale registration statement on Form S-3, filed with the SEC on September 21, 2023.

Preferred Stock

The Company is authorized to issue up to 10,000,000 shares of preferred stock, of whichno shares are currently issued or outstanding. Of those,200,000 shares of preferred stock were designated as series A junior participating preferred stock in connection with the Company’s now expired rights agreement.

Equity Compensation Awards

The 2020 Incentive Award Plan (as amended from time to time, the “2020 Plan”) provides for grants of equity awards to executive officers, other employees and directors, including restricted stock units (“RSUs”), performance stock units (“PSUs”), stock options, deferred stock units and other equity-based awards. In May 2020, the Company’s stockholders approved the 2020 Incentive Award Plan (the “2020 Plan”), which authorizes the issuance of 2,977,933 shares of Company common stock. In February 2022, the Company’s stockholders approved an amendment to the 2020 Plan, authorizing an additional 750,000 shares of Common stock. In March 2024 and March 2025, the Company’s stockholders approved an amendment to the 2020 Plan authorizing an additional 3,000,000 and 1,700,000 shares, respectively, of Company stock. At September 30, 2025, the aggregate number of shares of Company common stock available for grant was 3,823,000 shares.

During the fiscal years ended September 30, 2025, September 30, 2024, and September 30, 2023, the Company recorded non-cash stock-based compensation expense in selling, general, and administrative expense of $10.2 million, $10.1 million (includes $2.0 million paid in cash) and $21.1 million (includes $0.5 million paid in cash), respectively. The fair value of options vested was $0.3 million, $0.5 million and $0.8 million in the fiscal years ended September 30, 2025, September 30, 2024, and September 30, 2023, respectively.

As of September 30, 2025, unrecorded compensation cost related to non-vested awards of $6.8 million is expected to be recognized through 2026, with a weighted average period of 1.5 years.

Non-Employee Director Compensation. Non-employee directors may defer all or a portion of the fees payable for their service into deferred stock units, equivalent to the value of the Company’s common stock. The annual fees related to the director’s equity compensation were granted in deferred stock units or restricted stock units and will vest on the earlier of the day immediately preceding the Issuer’s next annual meeting (as long as the meeting is held at least 50 weeks from the grant date) and the first anniversary of the grant date. Additionally, these deferred stock units are entitled to accrete dividends in the form of additional units based on the stock price on the dividend payment date, if dividends are declared on the Company’s common stock. Accumulated deferred stock units are distributed in the form of Company common stock at a future specified date or following resignation from the Board of Directors, based upon the Director’s annual election. During the fiscal years ended September 30, 2025, September 30, 2024, and September 30, 2023, members of the Board of Directors were credited with 35,565,60,337 and 35,577 deferred stock units, respectively. During the fiscal years ended September 30, 2025, September 30, 2024, and September 30, 2023, the Directors were granted 47,620,22,740 and 14,945 restricted stock units, respectively. During the fiscal years ended September 30, 2025, September 30, 2024, and September 30, 2023,76,923,67,563 and 75,919 shares of common stock, respectively, were issued from treasury shares for Board of Director compensation related to quarterly fees payable and the release of deferred stock units.

RSUs. The RSUs granted under the 2020 Plan generally vest afterone tothree years of service entitling the holders toone share of common stock for each vested RSU. The unvested RSUs do not have voting rights but are entitled to receive non-forfeitable dividends or other distributions that may be declared on the Company’s common stock equal to the per-share dividend declared. The closing stock price on the date of each grant was used to determine the fair value of RSUs.

PSUs. Substantially all of the PSUs outstanding under the 2020 Plan are either total stockholder return PSUs (the “TSR PSUs”) or PSUs based upon several operational performance measures (“Scorecard PSUs”). The actual number of shares of the Company’s common stock that may be earned with respect to TSR PSUs is calculated by comparing the Company’s total stockholder return to the total stockholder return for each company comprising the Company’s peer group or a total return percentage target over atwo orthree-year performance period and may range from 0% to 300% of the target number of shares based upon the attainment of these performance conditions. The actual number of shares of common stock that may be earned with respect to Scorecard PSUs is calculated based upon the attainment of free cash flow, cash unit costs, cash unit cost reduction, capital expenditures and safety measures during the performance period and may range from 0% to 300%. Holders of PSUs do not have voting rights but are entitled to receive non-forfeitable dividends or other distributions equal to those declared on the Company’s common stock for PSUs that are earned, which are paid when the shares underlying the PSUs are issued.

To estimate the fair value of the TSR PSUs on the grant date for accounting purposes, the Company uses a Monte-Carlo simulation model, which simulates future stock prices of the Company as well as the Company’s peer group. This model uses historical stock prices to estimate expected volatility and the Company’s correlation to the peer group.

The input for the expected stock price volatility ranged from 47% to 66% based on the respective grant dates. In addition, the Company used inputs for the risk-free rate that ranged from 3.2% to 4.6% based on the respective grant dates, expected dividend yield of 0%, and the Company’s closing stock price on the grant date to estimate the fair value of the TSR PSUs. The Company’s closing stock price on the grant date was used to estimate the fair value of the Scorecard PSUs. The Company will adjust the expense of the Scorecard PSUs based upon its estimate of the number of shares that will ultimately vest at each reporting date during the vesting period.

On September 30, 2025, the TSR PSUs performance conditions were not met, and therefore 0% of the PSUs vested.

During the fiscal year ended September 30, 2025, the Company granted 289,941 PSUs based upon certain performance criteria and metrics (“2025 Scorecard PSUs”). The actual number of shares of common stock that may be earned with respect to 2025 Scorecard PSUs is calculated based upon the attainment of certain thresholds for free cash flow and return on capital employed during each year of thethree-year performance period and may range from 0% to 200% for each measure. Additionally, a modifier will increase or decrease the payout by 20% based upon relative total shareholder return against the Company’s peer group.

To estimate the fair value of the 2025 Scorecard PSUs on the grant date, the Company used a Monte-Carlo simulation model. This model uses historical stock prices to estimate expected volatility and the Company’s correlation to the peer group. The input for the expected stock price volatility ranged from 44% to 49% based on the respective grant dates. In addition, the

Company used inputs for the risk-free rate that ranged from 3.9% to 4.2% based on the respective grant dates, expected dividend yield of 0%, and the Company’s closing stock price on the grant date to estimate the fair value of the 2025 Scorecard PSUs. The Company will adjust the expense of the 2025 Scorecard PSUs based upon its estimate of the number of shares that will ultimately vest at each reporting date during the vesting period.

Options. Substantially all of the stock options granted under each of the plans vest ratably, in tranches, over afour-year service period. Unexercised options expire after seven years. Options do not have dividend or voting rights. Upon vesting, each option can be exercised to purchaseone share of the Company’s common stock. The exercise price of options is equal to the closing stock price on the day of grant. The Company did not grant any options during fiscal years ended September 30, 2025, September 30, 2024, and September 30, 2023.

The following is a summary of the Company’s stock option, RSU and PSU activity and related information for the following periods:

(a)Common stock issued for exercised options, vested RSUs and vested and earned PSUs were issued from treasury shares.

As of September 30, 2024, there were 187,023 options outstanding of which 154,898 were exercisable. The following table summarizes information about options outstanding and exercisable at September 30, 2025.

As of September 30, 2025, there wasno intrinsic value for options outstanding;101,537 options were exercisable withno intrinsic value. The number of shares held in treasury is sufficient to cover the net shares issued from all outstanding equity awards as of September 30, 2025.

Accumulated Other Comprehensive (Loss) Income

The Company’s comprehensive (loss) income is comprised of net (loss) income, net amortization of the change in the unrealized (loss) gain of the pension obligation, the change in the unrealized gain (loss) in other post-retirement benefits, the change in the unrealized gain on natural gas and foreign currency cash flow hedges, and CTA. The components of and changes in AOCL are as follows (in millions):

(a)With the exception of the CTA, for which no tax effect is recorded, the changes in the components of AOCL presented in the table are reflected net of applicable income taxes.

(b)The amounts reclassified from AOCL are recorded to product costs for losses and gains on cash flow hedges. The amounts reclassified from AOCL are recorded to other (income) expense related to defined benefit pension and other post-employment benefits.

(c)The Company recorded foreign exchange loss of $2.0 million and $0.2 million in the fiscal years ended September 30, 2025 and September 30, 2024, respectively, in AOCL related to intercompany notes which were deemed to be of a long-term investment nature.

14. DERIVATIVE FINANCIAL INSTRUMENTS

The Company is subject to various types of market risks, including interest rate risk, foreign currency exchange rate transaction and translation risk and commodity pricing risk. Management may take actions to mitigate the exposure to these types of risks, including entering into forward purchase contracts and other financial instruments. The Company manages a portion of its commodity pricing and foreign currency exchange rate risks by using derivative instruments. From time to time, the Company may enter into foreign exchange contracts to mitigate foreign exchange risk. The Company does not seek to engage in trading activities or take speculative positions with any financial instrument arrangement. The Company enters into natural gas derivative instruments and foreign currency derivative instruments with counterparties it views as creditworthy. However, the Company does attempt to mitigate its counterparty credit risk exposures by, among other things, entering into master netting agreements with some of these counterparties. The Company records derivative financial instruments as either assets or liabilities at fair value in its Consolidated Balance Sheets. The assets and liabilities recorded as of September 30, 2025 and September 30, 2024 were not material.

Derivatives qualify for treatment as hedges when there is a high correlation between the change in fair value of the derivative instrument and the related change in value of the underlying hedged item. Depending on the exposure being hedged, the Company must designate the hedging instrument as a fair value hedge, a cash flow hedge or a net investment in foreign operations hedge. For the qualifying derivative instruments that have been designated as cash flow hedges, the effective portion of the change in fair value is recorded through earnings when the underlying transaction being hedged affects earnings, allowing a derivative’s gains and losses to offset related results from the hedged item in the Consolidated Statements of Operations. Any ineffectiveness related to these instruments accounted for as hedges was not material for any of the periods presented. For derivative instruments that have not been designated as hedges, the entire change in fair value is recorded through earnings in the period of change.

Natural Gas Derivative Instruments

Natural gas is consumed at several of the Company’s production facilities, and changes in natural gas prices impact the Company’s operating margin. The Company seeks to reduce the earnings and cash flow impacts of changes in market prices of natural gas by fixing the purchase price of up to 90% of its forecasted natural gas usage. It is the Company’s policy to consider hedging portions of its natural gas usage up to 36 months in advance of the forecasted purchase. As of September 30, 2025, the Company had entered into natural gas derivative instruments to hedge a portion of its natural gas purchase requirements through December 31, 2026. As of September 30, 2025 and September 30, 2024, the Company had agreements in place to hedge forecasted natural gas purchases of 2.6 million and 2.3 million MMBtus, respectively.

On March 1, 2023, the Company de-designated its natural gas cash flow hedges related to its Ogden, Utah production facility as the Company did not believe these hedges were probable of being highly effective in the second fiscal quarter of 2023. Beginning March 1, 2023, the change in the derivative was recorded in other expense, net in the Consolidated Statements of

Operations. The Company recorded expense related to the hedges that were de-designated of $0.0 million, $0.8 million, and $2.9 million in other expense, net, during the fiscal years ended September 30, 2025, September 30, 2024, and September 30, 2023, respectively. Following the de-designation, these natural gas economic hedging instruments were recorded at fair value through earnings until settled. Substantially all other natural gas derivative instruments held by the Company as of September 30, 2025 and September 30, 2024 qualified and were designated as cash flow hedges. The Company recorded a net expense related to the natural gas cash flow hedges of $2.5 million, $4.7 million, and $4.7 million in Product costs, during the fiscal years ended September 30, 2025, September 30, 2024, and September 30, 2023, respectively. As of September 30, 2025, the Company expects to reclassify from AOCL to earnings during the next twelve months $0.9 million of net losses on derivative instruments related to its natural gas hedges. Refer to Note 15. Fair Value Measurements for the estimated fair value of the Company’s natural gas derivative instruments as of September 30, 2025 and September 30, 2024.

The following tables present the fair value of the Company’s derivatives (in millions):

(a)The Company has master netting agreements with its commodity hedge counterparties and accordingly has netted in its Consolidated Balance Sheets $7.8 million of its commodity contracts that are in receivable positions against its contracts in payable positions.

(a)The Company has master netting agreements with its commodity hedge counterparties and accordingly has netted in its Consolidated Balance Sheets $0.6 million of its commodity contracts that are in receivable positions against its contracts in payable positions.

The following tables present activity related to accumulated other comprehensive (loss) income before taxes (in millions):

15. FAIR VALUE MEASUREMENTS

The Company’s financial instruments are measured and reported at their estimated fair value. Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction. When available, the Company uses quoted prices in active markets to determine the fair values for its financial instruments (Level 1 inputs), or absent quoted market prices, observable market-corroborated inputs over the term of the financial instruments (Level 2 inputs). Level 3 inputs are unobservable inputs that are not corroborated by market data.

Recurring Fair Value Measurements

The following table summarizes the fair value hierarchy for each type of instrument carried at fair value on a recurring basis (in millions):

(a)Includes mutual fund investments of approximately 29% in the common stock of large-cap U.S. companies,4% in the common stock of small to mid-cap U.S. companies,2% in the common stock of international companies,9% in bond funds,20% in short-term investments and 36% in blended funds.

(b)The investments related to a non-qualified deferred compensation arrangement on behalf of certain members of management. The Company has a liability for the related-party transaction recorded in Other noncurrent liabilities for deferred compensation obligations.

(a)Includes mutual fund investments of approximately 35% in the common stock of large-cap U.S. companies,5% in the common stock of small to mid-cap U.S. companies,5% in the common stock of international companies,10% in bond funds,5% in short-term investments and 40% in blended funds.

(b)The investments related to a non-qualified deferred compensation arrangement on behalf of certain members of management. The Company has a liability for the related-party transaction recorded in Other noncurrent liabilities for deferred compensation obligation.

Valuation Techniques: The Company holds marketable securities associated with its deferred contribution and pre-tax savings plans, which are valued based on readily available quoted market prices. The Company utilizes derivative instruments to manage its risk of changes in natural gas prices and foreign exchange rates (see Note 14. Derivative Financial Instruments). The fair values of the natural gas and foreign currency derivative instruments are determined using market data of forward prices for all of the Company’s contracts.

Other Fair Value Measurements

The Company is required to disclose the fair value of financial instruments that are not recognized at fair value in the statement of financial position for which it is practicable to estimate that value (in millions):

Valuation Techniques: Observable market-based inputs were used to estimate fair value for Level 2 inputs, based on available trading information. Cash and cash equivalents, receivables (net of allowance for doubtful accounts) and accounts payable are carried at cost, which approximates fair value due to their liquid and short-term nature.

The following fair value hierarchy table summarizes the Company’s assets that were written down to their fair value on a nonrecurring basis (in millions):

(a) On March 31, 2025, the Company recorded an impairment loss of $53.0 million related to definite-lived intangible asset after determining that no future cash flows were expected from these assets. As a result, the Fortress definite-lived intangible asset was assigned a fair value of zero using the income approach under ASC 820. Fair Value Measurement (see Note 2. Summary of Significant Accounting Policies).

(b) On March 22, 2024, the Company recorded an impairment loss of $15.6 million related to definite-lived intangible asset associated with the magnesium chloride-related assets as a result of the evaluation using the income approach.

(c) On September 3, 2024, the Company recorded an impairment loss of $17.6 million related to definitive-lived intangible asset water right, due to the Voluntary Agreement of donating non-production related water rights to be used by the State of Utah for lake conservation and preservation.

(d) On June 30, 2025, Fortress-related property, plant and equipment, net with a carrying value of $0.7 million was written down to its fair value of $0, resulting in a loss on impairment, net of $0.7 million, due to no future expected use of property, plant and equipment, net at June 30. 2025.

(e) On January 23, 2024, the Company terminated its pursuit of its lithium development. Consequently, the Company evaluated the capitalized assets, including site preparation, project engineering, equipment and material and capitalized labor and interest and recorded an impairment charge of $74.8 million.

(f) On March 31, 2024, the Company performed the interim goodwill impairment test related to the Company’s Plant Nutrition segment, primarily due to decreases in projected future revenues and cash flows and an increase in discount rates due to the uncertain regulatory environment in Utah and recorded a goodwill impairment of $51.0 million. Following the impairment charge, there was no remaining goodwill balance for the Plant Nutrition reporting unit.

(g) On March 31, 2024, the Company recorded a goodwill impairment loss of $32.0 million related to the Company’s Fortress reporting unit included in the Corporate and Other segment, primarily due to the changes in assumptions surrounding the magnesium chloride-based fire retardants which impacted projected future revenues and cash flows. Following the impairment charges, there was no remaining goodwill balance for the Fortress reporting unit.

In connection with the aforementioned impairments, the Company determined the estimated fair value for each reporting unit based on discounted cash flow projections (income approach), market values for comparable assets (market approach) or a combination of both. Under the income approach, the Company is required to make judgments about appropriate discount rates, long-term revenue growth rates and the amount and timing of expected future cash flows. The cash flows used in its estimates are based on the reporting unit's forecast, long-term business plan, and recent operating performance. Discount rate assumptions are based on an assessment of the risk inherent in the future cash flows of the respective reporting unit and market conditions. The Company’s estimates may differ from actual future cash flows. The risk adjusted discount rate used is consistent with the weighted average cost of capital of the Company’s peer companies and is intended to represent a rate of return that would be expected by a market participant. Under the market approach, market multiples are derived from market prices of stocks of companies in the Company’s peer group. The appropriate multiple is applied to the forecasted revenue and earnings before interest, taxes, depreciation and amortization of the reporting unit to obtain an estimated fair value.

The most critical assumptions used in the calculation of the fair value of each reporting unit are the projected revenue growth rates, long-term operating margin, terminal growth rates, discount rate, and the selection of market multiples. The projected long term operating margin utilized in the Company’s fair value estimates is consistent with its operating plan and is dependent on the successful execution of its long-term business plan, overall industry growth rates and the competitive environment. In many of these estimates, the cash flows were zero due to the exiting of these businesses, and therefore, the estimations were limited. The discount rate could be adversely impacted by changes in the macroeconomic environment and volatility in the equity and debt markets. Although management believes its estimate of fair value is reasonable, if the future financial performance falls below expectations or there are unfavorable revisions to significant assumptions, or if the Company’s market capitalization declines, an additional non-cash goodwill or long-lived asset impairment charge may be required in a future period.

16. NET (LOSS) INCOME PER SHARE

Basic net (loss) income per share is computed by dividing net (loss) income available to common stockholders by the weighted-average number of outstanding common shares during the period. Diluted net (loss) income per share reflects the potential dilution that could occur under the more dilutive of either the treasury stock method or the two-class method for calculating the weighted-average number of outstanding common shares. Under the treasury stock method, potential shares of common stock include dilutive shares attributable to the assumed exercise of share options and vesting of RSUs and PSUs. Under the treasury stock method potential common shares outstanding are not included in the computation of diluted net (loss) income per share if their effect is anti-dilutive.

The following table sets forth the computation of basic and diluted net (loss) income per common share (in millions, except for share and per-share data):

(a)Weighted participating securities include PSUs and RSUs that receive non-forfeitable dividends. Net income was allocated to participating securities of 667,000 and 476,000 for the fiscal years ended September 30, 2024 and September 30, 2023, respectively.

(b)The Company had 1,481,000,1,286,000 and 1,264,000 weighted-average equity awards outstanding for fiscal years ended September 30, 2025, September 30, 2024, and September 30, 2023, respectively, that were anti-dilutive and not included in the calculation of diluted net (loss) income per common share.

17. RELATED PARTY TRANSACTIONS

As discussed in Note 13. Stockholders’ Equity and Equity Instruments, on October 18, 2022, Koch, through its KM&T subsidiary, purchased common stock representing an ownership interest of approximately 17% of the outstanding common stock of the Company.

During the fiscal years ended September 30, 2025, September 30, 2024, and September 30, 2023, the Company recorded SOP sales of approximately $3.6 million, $3.4 million, and $4.3 million, respectively, to certain subsidiaries of Koch. As of September 30, 2025 and September 30, 2024, the Company had approximately $0.2 million and $0.3 million, respectively, of receivables from related parties on its Consolidated Balance Sheets. There wereno outstanding amounts payable as of September 30, 2025 or September 30, 2024.

18. SUBSEQUENT EVENT

Canadian Provincial Tax. In November 2025, the Company reached a settlement with a Canadian provincial tax authority regarding a tax dispute for fiscal years 2002 - 2018. The Canadian provincial tax authority had challenged tax positions claimed by one of the Company’s Canadian subsidiaries and have issued tax reassessments for fiscal years 2002-2019. The reassessments were the result of ongoing audits and total$209.8 million, including interest. The settlement resolved the dispute for tax years 2002 - 2018 for a total expected cash outlay of $10 M, net of federal refunds and deductions associated with the agreed upon tax and interest. The total impacts of the settlement, net of federal benefits and subsequent year adjustments, as compared to the accrual recorded as of September 30, 2025 are expected to be immaterial. The settlement amount related to tax years 2002 - 2018 was paid in the first quarter of fiscal 2026 and the Company is in the process of amending the relevant tax returns to obtain the associated federal refunds. With the settlement, the bonds posted as collateral for the 2002-2018 period were released.