COMPASS MINERALS INTERNATIONAL INC

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

(Unaudited)

1. Accounting Policies and Basis of Presentation:

Compass Minerals International, Inc. (“CMI”), through its subsidiaries (collectively, 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 (“U.K.”). The Company also provides records management services in the U.K. Except where otherwise noted, references to North America include only the continental U.S. and Canada, and references to the U.K. include only England, Scotland and Wales. References to “Compass Minerals,” “our,” “us” and “we” refer to CMI and its consolidated subsidiaries.

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

The accompanying consolidated balance sheet as of September 30, 2024, which was derived from audited financial statements, and the unaudited consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete consolidated financial statements. As a result, these consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in the Company’s annual report on Form 10-K for the year ended September 30, 2024 (“2024-K”). In the opinion of management, these interim financial statements reflect all adjustments, consisting of normal recurring adjustments considered necessary for a fair presentation of the Company’s financial position and results of operations.

The Company experiences a substantial amount of seasonality in its sales, including its salt deicing product sales. Consequently, Salt segment sales and operating income are generally higher in the first and second fiscal quarters (ending December 31 and March 31) and lower during the third and fourth fiscal quarters (ending June 30 and September 30). In particular, sales of highway and consumer deicing salt and magnesium chloride products vary based on the severity of the winter conditions in areas where the products are used. Following industry practice in North America and the U.K., the Company seeks to stockpile sufficient quantities of deicing salt throughout the first, third and fourth fiscal quarters (ending December 31, June 30 and September 30) to meet the estimated requirements for the winter season. Production of deicing salt can also vary based on the severity or mildness of the preceding winter season. Due to the seasonal nature of the deicing product lines, operating results for the interim periods are not necessarily indicative of the results that may be expected for the full fiscal year. The Company’s plant nutrition business is also seasonal. As a result, the Company and its customers generally build inventories during the plant nutrition business’ low demand periods of the year (which are typically winter and summer, but can vary due to weather and other factors) to ensure timely product availability during the peak sales seasons (which are typically spring and autumn, but can also vary due to weather and other factors).

Fortress

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 reduced the headcount of its corporate workforce and began the process of exiting the Fortress North America, LLC (“Fortress”) fire retardant business, terminating the employment of all Fortress employees (see Note 9. Operating Segments for further information). As such, the Company will no longer allocate capital and resources to the Fortress fire retardant business and is no longer pursuing an approved fire retardant product.

Impairments. As a result of the above items impacting Fortress, the Company determined that there were indicators of impairment with the associated Fortress intangible assets. Therefore, the Company tested these intangible assets for impairment. As a result, the Company recorded a loss on impairment, net, of $0 and $53.0 million, for the three and nine months ended June 30, 2025, respectively, related to Customer relationships and Trade name (see Note 5. Goodwill and Other Intangible Assets and Note 12. Fair Value Measurements for further information).

Additionally, the Company performed an impairment test on the remaining Fortress asset group (including property, plant, and equipment (“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 12. 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. The fair value estimates involved significant estimates and assumptions, which may differ from actual outcomes.

At June 30, 2025, the Company performed an impairment test on the remaining Fortress asset group related to property, plant, and equipment and recorded a loss on impairment, net of $0.7 million, during the three and nine months ended June 30, 2025 (see Note 12. Fair Value Measurements for further information).

Equipment Lease. 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. The remaining equipment, with a carrying value of $2.7 million at June 30, 2025, is included in Property, plant and equipment, net, on the Consolidated Balance Sheets.

Contingent Consideration. In connection with the acquisition of Fortress on May 5, 2023, the Company entered into a contingent consideration arrangement for up to $28 million to be paid in cash and/or Compass Minerals common stock upon the achievement of certain performance measures over the next five years, and a cash earn-out based on volumes of certain Fortress fire retardant products sold over a 10-year period. The carrying value of the contingent consideration at December 31, 2024, was $7.9 million, with $0.1 million, included in Accrued expenses and other current liabilities and $7.8 million, included in Other noncurrent liabilities. Given the business ceased operations and had no future expected cash flows, the carrying value of the contingent consideration was reduced to $0 as of March 31, 2025. For the three and nine months ended June 30, 2025, the Company recorded income, included in Other operating expense (income), of $0 and $7.9 million, respectively. For the three and nine months ended June 30, 2024, the Company recorded income of $0.9 million and $23.1 million, respectively, included in Other operating expense (income).

Asset Purchase Agreement. On May 30, 2025, the Company entered into an Asset Purchase Agreement, selling substantially all Fortress assets for $20.0 million in cash. The Company paid approximately $0.4 million of costs related to the sale. The assets included in the sale had a net book value of approximately $17.2 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 three and nine months ended June 30, 2025.

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 liabilities and Other noncurrent liabilities line items, respectively, in the current year presentation, with conforming reclassifications made for the prior period presentation.

Recent Accounting Pronouncements

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 amendments are effective for fiscal years beginning after December 15, 2023, and for interim periods within fiscal years beginning after December 15, 2024. The amendments should be applied retrospectively to all prior periods presented in the financial statements. The Company will adopt the disclosure requirements of ASU 2023-07 beginning with the annual report for fiscal year ended September 30, 2025.

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.

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.

2. Revenues:

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 included in Accrued expenses and other current liabilities as of June 30, 2025 and September 30, 2024 was approximately $1.7 million and $3.6 million, respectively.

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

(a)Refer to Note 8. Commitments and Contingencies for additional information.

See Note 9. Operating Segments for a disaggregation of sales by segment, type and geographical region.

3. Inventories:

Inventories consist of the following (in millions):

(a)Excludes certain raw materials and supplies of $42.1 million and $42.2 million as of June 30, 2025 and September 30, 2024, respectively, that are not expected to be consumed within the next twelve months, included in Other noncurrent assets in the Consolidated Balance Sheets.

(b)Refer to Note 1. Accounting Policies and Basis of Presentation for details of the Fortress disposition during the period ended June 30, 2025.

4. Property, Plant and Equipment, Net:

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

(a)Refer to Note 1. Accounting Policies and Basis of Presentation for details of the Fortress disposition during the period ended June 30, 2025.

5. Goodwill and Other Intangible Assets:

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

During the three and nine months ended June 30, 2025, the Company recorded a loss on impairment, net, of $0 and $53.0 million, respectively, related to Fortress customer relationships and trade name definite-lived intangible assets of $52.9 million and $0.1 million, respectively. On May 30, 2025, the Company finalized the sale of the remaining Fortress-related assets, including the remaining $2.2 million of indefinite-lived in-process research and development intangible asset (see Note 1 for further information).

As of June 30, 2025 and September 30, 2024, net intangible assets were $24.6 million and $82.5 million, respectively. Accumulated amortization as of June 30, 2025 and September 30, 2024 was $30.0 million and $31.9 million, respectively. For the three months ended June 30, 2025 and June 30, 2024, aggregate amortization expense was $0.4 million and $1.0 million, respectively, and $2.4 million and $3.3 million for the nine months ended June 30, 2025 and June 2024, respectively. Aggregate amortization expense is projected to be between $1.0 million and $3.0 million per fiscal year over the next five years.

6. Income Taxes:

The Company’s effective income tax rate differs from the U.S. statutory federal income tax rate primarily due to U.S. statutory depletion, state income taxes (net of federal tax benefit), nondeductible executive compensation over $1 million, foreign income, mining and withholding taxes, base erosion and anti-abuse tax, and valuation allowances recorded on deferred tax assets.

The effective tax rates applied to the nine months ended June 30, 2025 were determined by excluding the U.S. losses from the overall estimated annual effective tax rate computations and a separate estimated annual effective tax rate was computed and applied to the ordinary U.S. losses.

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 June 30, 2025. Such objective evidence limits the ability to consider other subjective evidence, such as the Company’s projections for future income. On the basis of this evaluation, during the nine months ended June 30, 2025, an additional valuation allowance of $29.0 million has been recorded to recognize only the portion of the U.S. deferred tax assets that is 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 the Company’s projections for income.

As of June 30, 2025 and September 30, 2024, the Company had $79.6 million and $76.4 million, respectively of gross federal NOL carryforwards that have no expiration date and $7.0 million and $6.1 million at June 30, 2025 and September 30, 2024, respectively of net operating tax-effected state NOL carryforwards which expire beginning in 2031.

Canadian provincial tax authorities have 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 $210.4 million, including interest, through June 30, 2025. The Company disputes these reassessments and continues to work with the appropriate authorities in Canada to resolve the dispute. There is a reasonable possibility that the ultimate resolution of this dispute, and any related disputes for other open tax years, may be materially higher or lower than the amounts the Company has reserved for such disputes. 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 $160.5 million performance bond and has paid $36.5 million to the Canadian tax authorities (most of which is recorded in other assets in the Consolidated Balance Sheets at June 30, 2025, and September 30, 2024), which is necessary to proceed with future appeals or litigation.

The Company could be required by local regulations to provide security for additional interest on the above unresolved disputed amounts and for any future reassessments issued by these Canadian tax authorities in the form of cash, letters of credit, performance bonds, asset liens or other arrangements agreeable with the tax authorities until the disputes are resolved.

The Company expects that the ultimate outcome of these matters will not have a material impact on its results of operations or financial condition. However, the Company can provide no assurance as to the ultimate outcome of these matters, and the impact could be material if they are not resolved in the Company’s favor. As of June 30, 2025, the Company believes it has adequately reserved for these reassessments.

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

On July 4, 2025, the U.S. enacted a budget reconciliation package known as the “One Big Beautiful Bill Act of 2025” (“OBBBA”), which includes both tax and non-tax provisions. The Company is evaluating the effects of these changes and other provisions of this legislation on our consolidated financial statements; however, the Company does not expect the changes resulting from the tax provisions in OBBBA will have a material impact on its results of operations due to the timing of its fiscal year reporting.

7. Long-Term Debt and Finance Lease Liabilities:

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

Senior Notes Offering

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 $13.3 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 approximately $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. The redemption, completed on June 17, 2025, resulted in a loss on debt extinguishment of $5.7 million, included in Loss on extinguishment of debt in the Consolidated Statements of Operations for the three and nine months ended June 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 $0.8 million as of June 30, 2025.

Prior to July 1, 2027, the Company may redeem some or all of the 2030 Notes up to 40% of the aggregate principal amount with equity offering proceeds at a redemption price equal to 108% 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% of the principal amount thereof, declining ratably to 100% 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, originally dated April 20, 2016, as amended (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) replace the current leverage-based covenant, which required compliance with a maximum ratio of consolidated total net indebtedness to 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) lower 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. 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 on the Consolidated Statements of Operations for the three and nine months ended June 30, 2025, related to the write-off of unamortized deferred financing costs.

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, plus applicable margins, subject to a floor of 0.0%. As of June 30, 2025, no borrowings were outstanding under the revolving credit facility. Also, as of June 30, 2025, outstanding letters of credit totaling $15.7 million reduced available borrowing capacity to $309.3 million.

As of September 30, 2024, the weighted average interest rate on all borrowings outstanding under the Amended and Restated 2023 Credit Agreement was approximately 7.7%. Depending on the type, borrowings under the Amended and Restated 2023 Credit Agreement accrued interest at a rate per annum between 7.3% and 9.5% as of September 30, 2024.

Prior Amendment to the Credit Agreement

On December 12, 2024, the Company entered into an amendment to its 2023 Credit Agreement, 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 4.50 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 this amendment, the Company paid fees totaling $2.0 million, which were capitalized as deferred financing costs and will be amortized to interest expense over the term of the amended 2023 Credit Agreement. Additional arrangement and legal fees of $0 and $1.0 million were recorded to Other expense during the three and nine months ended June 30, 2025, respectively.

Covenant Compliance and Other Information

The consolidated total net leverage ratio, as defined in the Amended and Restated 2023 Credit Agreement, represents the ratio of consolidated total net debt (aggregate principal amount of total debt, net of unrestricted cash not to exceed $100.0 million) to consolidated adjusted earnings before interest, taxes, depreciation, and amortization. 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 June 30, 2025, the Company was in compliance with these covenants.

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

8. Commitments and Contingencies:

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 6. Income Taxes and this Note 8.

On October 21, 2022, a putative securities class 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 preliminary approval of the settlement was filed with the court on March 28, 2025, and

was granted by the court on April 7, 2025. 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 committed to pay the agreed upon settlement. The Company has recorded a liability and corresponding insurance recoveries, included in Receivables, in its Consolidated Balance Sheets as of June 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. The parties have stipulated to stay this matter through the discovery stage of the putative securities class action. 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 preliminary approval of the settlement was filed with the court on July 14, 2025.

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 preliminary settlement agreement dated June 30, 2025, to resolve the matter, which has been consented to by the Company’s insurers. The court granted preliminary approval of the settlement on July 25, 2025, and scheduled a hearing on November 4, 2025, to consider any objections and whether to finally approve 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. By order dated June 25, 2025, the court extended plaintiffs’ time to file a consolidated complaint until July 30, 2025, and set August 29, 2025, as the deadline for defendants to respond to the consolidated complaint. 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 amended complaint asserts five claims: (1) violation of Section 14(a) of the Securities and Exchange Act of 1934 (the “Exchange Act”); (2) breach of fiduciary duty; (3) unjust enrichment; (4) waste of corporate assets; and (5) for contribution under Sections 10(b) and 21D of the Exchange Act (against certain former directors and officers). Pursuant to the current scheduling order, the defendant’s response to the amended complaint is due August 29, 2025.

The Company previously had contingent consideration liabilities related to the Fortress acquisition. As a result of the Company’s exit of the Fortress business, a non-cash gain of $7.9 million was recorded during the nine months ended June 30, 2025 to reduce the fair value of the contingent consideration liability tozero. Refer to Note 1. Accounting Policies and Basis of Presentation for additional information.

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 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 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 June 30, 2025, the Company has recorded a liability of $101.1 million, included in Accrued expenses and other current liabilities, and estimated insurance recoveries of $95.9 million, included in Receivables, in the Consolidated Balance Sheets associated with the recall matters described above, in addition to all other legal and administrative proceedings.

9. 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 the three and nine months ended June 30, 2025 and June 30, 2024, the Company has presentedtwo reportable segments in its Consolidated Financial Statements: Salt and Plant Nutrition. The Salt segment produces and markets salt, consisting of sodium chloride and magnesium chloride, for use in road deicing for winter roadway safety and for dust control, food processing, water softening 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 fire retardant and records management businesses are included in Corporate and Other in the tables below (see Note 1. Accounting Policies and Basis of Presentation for further information on the exit of the Fortress fire retardant business).

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, the Fortress fire retardant business, equity method investments, prior-year lithium costs and other incidental operations and eliminations. Operating earnings (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)Corporate operating results were impacted by costs related to a product recall of $0.2 million and $2.0 million for the three and nine months ended June 30, 2025, respectively. Corporate operating results were also impacted by declines in the valuation of the Fortress contingent consideration. The Company recorded net gains of $7.9 million for the nine months ended June 30, 2025, and $0.9 million and $23.1 million for the three and nine months ended June 30, 2024, respectively, related to the Fortress contingent consideration valuation.

(c)The Company recorded impairment of $0.7 million and $53.7 million related to the exit of the Fortress fire retardant business for the three and nine months ended June 30, 2025, respectively, which impacted operating results. Refer to Note 1. Accounting Policies and Basis of Presentation for additional details. The Company also recorded impairments of $175.8 million related to the impairment of Plant Nutrition goodwill, Fortress assets and goodwill and lithium development assets for the nine months ended June 30, 2024, which impacted operating results.

(d)The Company continued to take steps to align its cost structure to its current business needs. These initiatives impacted Corporate operating results and resulted in net severance and related charges, excluding stock-based compensation forfeitures, for reductions in workforce and changes to executive leadership and additional restructuring costs related to the exit of the Fortress fire retardant business of $0.3 million and $4.3 million for the three and nine months ended June 30, 2025, respectively. The Company also recorded net severance and related charges, excluding stock-based compensation forfeitures, for reductions in workforce and changes to executive leadership and additional restructuring costs related to the termination of the Company’s lithium development project of $1.5 million and $17.2 million for the three and nine months ended June 30, 2024, respectively.

The Company’s revenue by geographic area is as follows (in millions):

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

10. Stockholders’ Equity and Equity Instruments:

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.

Stock-based compensation expense recorded in selling, general and administrative expenses in the Consolidated Statements of Operations was $2.7 million and $0.6 million for the three months ended June 30, 2025 and June 30, 2024, respectively, and $8.6 million and $17.8 million for the nine months ended June 30, 2025 and June 30, 2024, respectively. Stock-based compensation expense recorded in other operating expense (income) in the Consolidated Statements of Operations due to restructuring was $(2.1) million and $(0.8) million (includes $0.5 million paid in cash) for the three months ended June 30, 2025 and June 30, 2024, respectively, and $(1.3) million and $(9.7) million (includes $1.8 million paid in cash) for the nine months ended June 30, 2025 and June 30, 2024, respectively. As of June 30, 2025, there was approximately $7.2 million of total estimated unrecognized compensation cost, assuming attainment of the performance target estimates, related to stock-based compensation arrangements expected to be recognized over a weighted average period of approximately 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. In relation to these annual fees, the Company granted 47,620 RSUs and 22,322 deferred stock units to the Board of Directors during the nine months ended June 30, 2025. Additionally, as dividends are declared on the Company’s common stock, 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. 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 nine months ended June 30, 2025, common shares of 48,192 were issued from treasury shares for Board of Director compensation related to quarterly fees payable and the release of deferred stock units.

RSUs. During the nine months ended June 30, 2025, the Company granted 874,938 RSUs which 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. During the nine months ended June 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 interim date during the vesting period.

Options. Substantially all of the stock options granted 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 following table summarizes stock-based compensation activity during the nine months ended June 30, 2025:

(a)Until the performance period is completed, PSUs are included in the table at the target level at their grant date and at that level representone share of common stock per PSU.

(b)Common stock was reissued from treasury shares for vested and earned RSUs, net of units surrendered in lieu of taxes of 113,656 units, during the nine months ended June 30, 2025. As a result, the Company paid taxes for restricted unit withholding of approximately $1.3 million during the nine months ended June 30, 2025.

Accumulated Other Comprehensive Loss (“AOCL”)

The Company’s comprehensive income (loss) is comprised of net loss, net amortization of the unrealized loss of the pension obligation, the change in the unrealized gain in other postretirement benefits, the change in the unrealized gain (loss) on natural gas and foreign currency cash flow hedges and currency translation adjustment (“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 tables above are reflected net of applicable income taxes.

(b)The Company recorded foreign exchange gain of $0.2 million in the nine months ended June 30, 2025, in AOCL related to intercompany notes which were deemed to be of a long-term investment nature.

(c)The amounts reclassified from AOCL to expense (income) impacted the product cost line item in the Consolidated Statements of Operations.

11. 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 risks 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 June 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 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. 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 June 30, 2025, the Company had entered into natural gas derivative instruments to hedge a portion of its natural gas purchase requirements through September 2026. As of June 30, 2025 and September 30, 2024, the Company had agreements in place to hedge forecasted natural gas purchases of 1.4 millionand 2.3 million MMBtus, respectively. All natural gas derivative instruments held by the Company as of June 30, 2025 and September 30, 2024 qualified and were designated as cash flow hedges. As of June 30, 2025, the Company expects to reclassify from AOCL to earnings during the next twelve months $0.3 million of net

losses on derivative instruments related to its natural gas hedges. Refer to Note 12. Fair Value Measurements for the estimated fair value of the Company’s natural gas derivative instruments as of June 30, 2025.

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 $0.7 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.

12. Fair Value Measurements:

The Company’s financial instruments are measured and reported at their estimated fair values. 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). The Company does not have any unobservable inputs that are not corroborated by market inputs (Level 3 inputs), except as stated below.

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 25% in common stock of large-cap U.S. companies,5% in common stock of small to mid-cap U.S. companies,10% in bond funds,20% 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 on 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 11. 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) At March 31, 2025, the Company recorded an impairment loss of $53.0 million related to definite-lived intangible assets after determining that no future cash flows were expected from these assets. As a result, the Fortress definite-lived intangible assets were assigned a fair value ofzero using the income approach under ASC 820, Fair Value Measurement (see Note 1. Accounting Policies and Basis of Presentation for further information).

(b) At June 30, 2025, Fortress-related property, plant, and equipment, net with a carrying value of $0.7 million was written down to their 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.

13. Earnings per Share:

On April 22, 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 Company calculated earnings per share using the treasury stock method during the three and nine months ended June 30, 2025. The Company calculated earnings per share using the two-class method during the three and nine months ended June 30, 2024. The two-class method requires allocating the Company’s net earnings to both common shares and participating securities. The following table sets forth the computation of basic and diluted earnings (loss) per common share (in millions, except for share and per-share data):

(a)Weighted participating securities include RSUs and PSUs that receive non-forfeitable dividends and consist of 632,000 and 698,000 weighted participating securities for the three and nine months ended June 30, 2024, respectively.

(b)For the calculation of diluted net earnings (loss) per share, the Company uses the more dilutive of either the treasury stock method or the two-class method to determine the weighted-average number of outstanding common shares. The Company had 1,558,000 and 1,657,000 weighted-average equity awards outstanding for the three and nine months ended June 30, 2025, respectively, and 874,000 and 1,427,000 weighted-average equity awards outstanding for the three and nine months ended June 30, 2024, respectively, that were anti-dilutive.

14. Related Party Transactions:

During the three and nine months ended June 30, 2025, the Company recorded SOP sales from related parties of approximately $0.9 million and $2.9 million, respectively, to certain subsidiaries of Koch, Inc., compared to $0.9 million and $2.7 million, respectively, during the three and nine ended June 30, 2024. As of June 30, 2025 and September 30, 2024, the Company recorded approximately $0.4 million and $0.3 million, respectively, of receivables from related parties on its Consolidated Balance Sheets. There wereno payable amounts outstanding as of June 30, 2025.