Ecovyst Inc. 10-K

ITEM 9A. CONTROLS AND PROCEDURES. Evaluation of Disclosure Controls and Procedures Our management, with the participation of our Chief Executive Officer and Chief Financial Officer, evaluated the effectiveness of our disclosure controls and procedures as of December 31, 2025. The term “disclosure controls and procedures,” as defined in Rules 13a-15(e) and 15d-15(e) under the Exchange Act, means controls and other procedures of a company that are designed to provide reasonable assurance that information required to be disclosed by a company in the reports that it files or submits under the Exchange Act is recorded, processed, summarized and reported within the time periods specified in the SEC’s rules and forms. Disclosure controls and procedures include, without limitation, controls and procedures designed to provide reasonable assurance that information required to be disclosed by a company in the reports that it files or submits under the Exchange Act is accumulated and communicated to the company’s management, including its principal executive and principal financial officers, as appropriate to allow timely decisions regarding required disclosure. 57 Table of Contents Management recognized that any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving their objectives and management necessarily applies its judgment in evaluating the cost-benefit relationship of possible controls and procedures. Based on that evaluation, our Chief Executive Officer and Chief Financial Officer concluded that, as of such date, our disclosure controls and procedures were effective at a reasonable assurance level. Management’s Annual Report on Internal Control over Financial Reporting Our management is responsible for establishing and maintaining adequate internal control over financial reporting. Internal control over financial reporting is defined in Rules 13a-15(f) and 15d-15(f) under the Exchange Act as a process, designed by, or under the supervision of the Company’s principal executive and principal financial officers and effected by the Company’s board of directors, management and other personnel, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. Internal control over financial reporting includes maintaining records that in reasonable detail accurately and fairly reflect our transactions and dispositions of assets; providing reasonable assurance that transactions are recorded as necessary for preparation of our financial statements; providing reasonable assurance that receipts and expenditures are made only in accordance with management and board authorizations; and providing reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use or disposition of our assets that could have a material effect on our financial statements. Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate. Our management assessed the effectiveness of our internal control over financial reporting as of December 31, 2025. In making this assessment, management used the criteria for effective internal control over financial reporting described in the “Internal Control-Integrated Framework” (2013) set forth by the Committee of Sponsoring Organizations of the Treadway Commission (“COSO”). Based on the assessment, management concluded that, as of December 31, 2025, our internal control over financial reporting was effective based on those criteria. The effectiveness of our internal control over financial reporting as of December 31, 2025 has been audited by PricewaterhouseCoopers LLP, an independent registered public accounting firm, as stated in their report, which is included in Item 8. Previously Disclosed Material Weakness As a result of our sale of the Advanced Materials & Catalysts segment, the associated risks and controls related to the accounting of the Zeolyst Joint Venture no longer exist, nor does the corresponding material weakness identified to have existed at December 31, 2024. Changes in Internal Control Over Financial Reporting No changes in our internal control over financial reporting occurred during the quarter ended December 31, 2025 that materially affected, or which are reasonably likely to materially affect, our internal control over financial reporting. ITEM 9B. OTHER INFORMATION. Trading Arrangements During the quarter ended December 31, 2025, none of the Company’s directors or executive officers adopted or terminated a “Rule 10b5-1 trading arrangement” or “non-Rule 10b5-1 trading arrangement,” as each item is defined in Item 408(a) of Regulation S-K. Share Repurchase Program Modification On October 30, 2025, our Board amended our Stock Repurchase Program to remove the limitation that all repurchases must be made within the four-year period from the date of original approval on April 27, 2022. ITEM 9C. DISCLOSURE REGARDING FOREIGN JURISDICTIONS THAT PREVENT INSPECTIONS. Not applicable. 58 Table of Contents PART III ITEM 10. DIRECTORS, EXECUTIVE OFFICERS AND CORPORATE GOVERNANCE. The Company has an insider trading policy which governs the purchase, sale, and/or other dispositions of its securities by the Company and its officers, directors, and other covered persons. The Company believes its insider trading policy is reasonably designed to promote compliance with insider trading laws, rules and regulations, as well as applicable listing standards. A copy of our form of insider trading policy is filed as Exhibit 19.1 to this Annual Report on Form 10-K. The remaining information required by this Item 10 will be included in our 2026 Proxy Statement, which we intend to file with the SEC within 120 days of our December 31, 2025 fiscal year end, and is incorporated herein by reference. ITEM 11. EXECUTIVE COMPENSATION. The information required by this Item 11 will be included in our 2026 Proxy Statement, which we intend to file with the SEC within 120 days of our December 31, 2025 fiscal year end, and is incorporated herein by reference. ITEM 12. SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT AND RELATED STOCKHOLDER MATTERS. The information required by this Item 12 will be included in our 2026 Proxy Statement, which we intend to file with the SEC within 120 days of our December 31, 2025 fiscal year end, and is incorporated herein by reference. ITEM 13. CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS, AND DIRECTOR INDEPENDENCE. The information required by this Item 13 will be included in our 2026 Proxy Statement, which we intend to file with the SEC within 120 days of our December 31, 2025 fiscal year end, and is incorporated herein by reference. ITEM 14. PRINCIPAL ACCOUNTANT FEES AND SERVICES. The information required by this Item 14 will be included in our 2026 Proxy Statement, which we intend to file with the SEC within 120 days of our December 31, 2025 fiscal year end, and is incorporated herein by reference. 59 Table of Contents PART IV ITEM 15. EXHIBIT AND FINANCIAL STATEMENT SCHEDULES. (a) The following documents are filed as part of this report: (1) and (2) The response to this portion of Item 15 is submitted as a separate section of this report beginning on page F-1. All other schedules have been omitted as inapplicable or are not required, or because the required information is included in the consolidated financial statements or accompanying notes. (3) The exhibits filed as part of this report are listed in the accompanying index. Incorporated by Reference Exhibit No. Exhibit Description Filed Herewith Form File No. Exhibit Filing Date 2.1 Stock Purchase Agreement, dated as of February 28, 2021, by and among PQ Group Holdings Inc. and Sparta Aggregator L.P. 8-K 001-38221 2.1 03/04/2021 2.2 Amendment No. 1 to Stock Purchase Agreement, dated as of June 24, 2021, by and among PQ Group Holdings Inc. and Sparta Aggregator L.P. 8-K 001-38221 2.1 6/30/2021 2.3 Amendment No. 2 to Stock Purchase Agreement, dated as of July 12, 2021, by and among PQ Group Holdings Inc. and Sparta Aggregator L.P. 8-K 001-38221 2.1 7/15/2021 2.4 Stock Purchase Agreement, dated as of September 10, 2025, by and between Ecovyst Inc. and Technip Energies N.V 8-K 001-38221 2.1 9/11/2025 3.1 Second Restated Certificate of Incorporation 10-Q 001-38221 3.1 11/14/2017 3.2 Certificate of Amendment of Certificate of Incorporation 8-K 001-38221 3.1 8/3/2021 3.3 Certificate of Correction of Certificate of Amendment of Certificate of Incorporation 10-Q 001-38221 3.3 11/9/2021 3.4 Second Amended and Restated Bylaws of Ecovyst Inc. 8-K 001-38221 3.2 8/3/2021 3.5 Certificate of Amendment of Certificate of Incorporation 8-K 001-38221 3.1 5/9/2024 4.1 Description of Ecovyst Inc.’s C ommon S tock X 10.1* Ecovyst Inc. 2017 Omnibus Incentive Plan, as Amended and Restated S-8 333-262180 4.1 1/14/2022 10.2* Form of Stock Option Award Agreement under the Ecovyst Inc. 2017 Omnibus Incentive Plan, as Amended and Restated 10-K 001-38221 10.7 3/1/2022 10.3* Form of Restricted Stock Award Agreement under the Ecovyst Inc. 2017 Omnibus Incentive Plan, as Amended and Restated 10-K 001-38221 10.8 3/1/2022 10.4* Form of Restricted Stock Unit Award Agreement under the Ecovyst Inc. 2017 Omnibus Incentive Plan, as Amended and Restated 10-K 001-38221 10.9 3/1/2022 10.5* Form of 2019 Performance Stock Unit Award Agreement under the Ecovyst Inc. 2017 Omnibus Incentive Plan, as Amended and Restated 10-K 001-38221 10.10 3/1/2022 10.6* Form of 2020 Performance Stock Unit Award Agreement under the Ecovyst Inc. 2017 Omnibus Incentive Plan, as Amended and Restated 10-K 001-38221 10.11 3/1/2022 10.7* PQ Group Holdings Inc. Stock Incentive Plan S-1 333-218650 10.6 6/9/2017 10.8* Form of Nonqualified Stock Option Award Agreement under the PQ Group Holdings Inc. Stock Incentive Plan S-1 333-218650 10.7 6/9/2017 60 Table of Contents Incorporated by Reference Exhibit No. Exhibit Description Filed Herewith Form File No. Exhibit Filing Date 10.9* Form of Restricted Stock Agreement under the PQ Group Holdings Inc. Stock Incentive Plan S-1 333-218650 10.8 6/9/2017 10.10* Form of Director and Officer Indemnification Agreement S-1/A 333-218650 10.9 9/1/2017 10.11* Severance Agreement, dated September 25, 2017, by and between PQ Corporation and Joseph S. Koscinksi 10-K 001-38221 10.37 2/27/2020 10.12 Term Loan Credit Agreement, dated as of June 9, 2021 among CPQ Midco I Corporation, PQ Corporation, Ecovyst Catalyst Technologies LLC, Eco Services Operations Corp., Credit Suisse AG, Cayman Islands Branch, as administrative agent and collateral agent, and the lenders from time to time party thereto, with Citibank, N.A., Credit Suisse Loan Funding LLC, BofA Securities, Inc., Deutsche Bank Securities Inc., Goldman Sachs Bank USA, KeyBanc Capital Markets Inc. and Truist Securities, Inc., as Joint Lead Arrangers and Joint Bookrunners 8-K 001-38221 10.1 6/11/2021 10.13 Third Amendment Agreement, dated as of June 9, 2021, to the ABL Credit Agreement, dated as of May 4, 2016, by and among PQ Corporation, CPQ Midco I Corporation, the Canadian Borrowers from time to time party thereto, the European Borrowers from time to time party thereto, the Lenders from time to time party thereto and Citibank, N.A., as Administrative Agent and Issuing Bank, with Citigroup Global Markets Inc., Credit Suisse Loan Funding LLC, Bank of America, N.A., Deutsche Bank Securities Inc., Goldman Sachs Bank USA, KeyBanc Capital Markets Inc. and Truist Securities, Inc., as Joint Lead Arrangers and Joint Bookrunners 8-K 001-38221 10.2 6/11/2021 10.14* Amendment to Form of Director and Officer Indemnification Agreement 10-Q 001-38221 10.3 8/9/2021 10.15* Form of Ecovyst Inc. Director and Officer Indemnification Agreement 10-Q 001-38221 10.4 8/9/2021 10.16* Form of 2021 Performance Stock Unit Award Agreement under the Ecovyst Inc. 2017 Omnibus Incentive Plan, as Amended and Restated 10-K 001-38221 10.38 3/1/2022 10.17 * Severance Agreement, dated December 16, 2022, between Ecovyst Catalyst Technologies LLC and Kurt J. Bitting 8-K 001-38221 10.1 12/16/2022 10.18* Severance Agreement, dated December 16, 2022, between Ecovyst Catalyst Technologies LLC and Michael Feehan 8-K 001-38221 10.2 12/16/2022 10.19* Amended and Restated Severance Agreement, dated December 16, 2022, between Ecovyst Catalyst Technologies LLC and Joseph S. Koscinski 8-K 001-38221 10.3 12/16/2022 10.20 First Amendment Agreement, dated February 9, 2023 to the Term Loan Credit Agreement, dated June 9, 2021, by and among Ecovyst Catalyst Technologies LLC , Ecovyst Midco II Inc, Eco Services Operations Corp and Credit Suisse AG 10-K 001-38221 10.27 2/28/2023 10.21 Fourth Amendment Agreement, dated February 17, 2023 to the ABL Credit Agreement, dated May 4, 2016 by and among Ecovyst Catalyst Technologies LLC, Ecovyst Catalyst Technologies UK Limited, Ecovyst Midco II Inc. and Citibank, N.A. 10-K 001-38221 10.28 2/28/2023 61 Table of Contents Incorporated by Reference Exhibit No. Exhibit Description Filed Herewith Form File No. Exhibit Filing Date 10.22* Letter of employment, dated July 19, 2022, between Ecoservices and George L. Vann 10-K 001-38221 10.30 2/28/2023 10.23* Letter of employment, dated November 28, 2022, between Ecovyst Catalyst Technologies LLC and Paul Whittleston 10-K 001-38221 10.31 2/28/2023 10.24* Form of 2024 Performance Stock Unit Award Agreement under the Ecovyst Inc. 2017 Omnibus Incentive Plan, as Amended and Restated 10-Q 001-38221 10.1 5/03/2024 10.25 Second Amendment Agreement, dated as of June 12, 2024, by and among the Borrowers, Ecovyst Midco II Inc., UBS AG Cayman Islands Branch, as administrative agent, and the lenders party thereto. 10-Q 001-38221 10.1 8/02/2024 10.26 Third Amendment Agreement, dated as of January 30, 2025, by and among the Borrowers, Ecovyst Midco II Inc., UBS AG, Stamford Branch, as administrative agent, and the lenders party thereto 8-K 001-38221 10.1 1/31/2025 10.27 ABL Credit Agreement, dated as of May 4, 2016, by and among PQ Corporation, CPQ Midco I Corporation, the Canadian Borrowers from time to time party thereto, the European Borrowers from time to time party thereto, the Lenders from time to time party thereto and Citibank, N.A., as Administrative Agent and Collateral Agent, with Citigroup Global Markets Inc., Credit Suisse Securities (USA) LLC, JPMorgan Chase Bank, N.A., Morgan Stanley Senior Funding, Inc., Deutsche Bank Securities Inc., Goldman Sachs Lending Partners LLC, Jefferies Finance LLC and KeyBanc Capital Markets Inc., as Joint Lead Arrangers and Joint Bookrunners S-1 333-218650 10.3 6/09/2017 10.28 First Amendment Agreement, dated as of March 20, 2020, to the ABL Credit Agreement, dated as of May 4, 2016, by and among PQ Corporation, CPQ Midco I Corporation, the Canadian Borrowers from time to time party thereto, the European Borrowers from time to time party thereto, the Guarantors from time to time party thereto, the Replacement Lenders from time to time party thereto, and Citibank, N.A., as Administrative Agent and as Collateral Agent 8-K 001-38221 10.1 05/11/2020 10.29 Fifth Amendment Agreement, dated as of April 10, 2025 to the ABL Credit Agreement, dated as of May 4, 2016, by and among Ecovyst Catalyst Technologies LLC, Ecovyst Catalyst Technologies UK Limited, Ecovyst Midco II Inc., the guarantors party thereto, the replacement lenders party thereto and Citibank, N.A., as administrative agent and collateral agent 8-K 001-38221 10.1 4/11/2025 10.30* Transition Agreement and General Release, effective as of August 11, 2025, between Ecovyst Inc. and George L. Vann, Jr. 10-Q 001-38221 10.1 10/05/2025 19.1 Form of Insider Trading Policy 10-K 001-38221 19.1 2/28/2025 21.1 Subsidiaries of Ecovyst Inc. X 23.1 Consent of PricewaterhouseCoopers LLP related to the consolidated financial statements and financial statement schedule of Ecovyst Inc. as of December 31, 2025 and 2024 and for each of the three years in the period ended December 31, 2025 X 62 Table of Contents Incorporated by Reference Exhibit No. Exhibit Description Filed Herewith Form File No. Exhibit Filing Date 23.2 Consent of PricewaterhouseCoopers LLP related to the financial statements of Zeolyst International as of December 31, 2025 and 2024 and for each of the three years in the period ended December 31, 2025 X 31.1 Certification of Chief Executive Officer of Ecovyst Inc. pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 X 31.2 Certification of Chief Financial Officer of Ecovyst Inc. pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 X 32.1** Certification of Chief Executive Officer of Ecovyst Inc. pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 X 32.2** Certification of Chief Financial Officer of Ecovyst Inc. pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 X 97.1 Policy relating to Recovery of Erroneously Awarded Compensation 10-K 001-38221 97.1 2/29/2024 101 The following financial statements from the Annual Report on Form 10-K of Ecovyst Inc. for the year ended December 31, 2025, formatted in Inline XBRL: (i) Consolidated Statements of (Loss) Income, (ii) Consolidated Statements of Comprehensive (Loss) Income, (iii) Consolidated Balance Sheets, (iv) Consolidated Statements of Stockholders’ Equity, (v) Consolidated Statements of Cash Flows, and (vi) Notes to Consolidated Financial Statements, tagged as blocks of text and including detailed tags X 104 The cover page from the Annual Report on Form 10-K of Ecovyst Inc. for the year ended December 31, 2025, formatted in Inline XBRL X * Management contract or compensatory plan ** This certification is being furnished pursuant to 18 U.S.C. Section 1350 and is not being filed for purposes of Section 18 of the Exchange Act and is not to be incorporated by reference into any filing of the registrant, whether made before or after the date hereof. ITEM 16. FORM 10-K SUMMARY. None. 63 Table of Contents SIGNATURES Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized. ECOVYST INC. Date: February 27, 2026 By: /s/ MICHAEL FEEHAN Michael Feehan Vice President and Chief Financial Officer (Duly Authorized Officer and Principal Financial and Accounting Officer) 64 Table of Contents Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated. Signature Title Date /s/ KURT J. BITTING Chief Executive Officer and Director February 27, 2026 Kurt J. Bitting (Principal Executive Officer) /s/ MICHAEL FEEHAN Vice President and Chief Financial Officer February 27, 2026 Michael Feehan (Principal Financial and Accounting Officer) /s/ KEVIN M. FOGARTY Chairperson of the Board February 27, 2026 Kevin M. Fogarty /s/ DAVID A. BRADLEY Director February 27, 2026 David A. Bradley /s/ BRYAN K. BROWN Director February 27, 2026 Bryan K. Brown /s/ ANNA CATALANO Director February 27, 2026 Anna Catalano /s/ SUSAN F. WARD Director February 27, 2026 Susan F. Ward /s/ SARAH LORANCE Director February 27, 2026 Sarah Lorance /s/ DONALD ALTHOFF Director February 27, 2026 Donald Althoff 65 Table of Contents INDEX TO CONSOLIDATED FINANCIAL STATEMENTS ECOVYST INC. AND SUBSIDIARIES Audited Consolidated Financial Statements Report of Independent Registered Public Accounting Firm (PCAOB ID 238 ) F- 2 Consolidated Statements of (Loss) Income for the Years Ended December 31, 2025, 2024 and 2023 F- 4 Consolidated Statements of Comprehensive (Loss) Income for the Years Ended December 31, 2 025, 2024 and 2023 F- 5 Consolidated Balance Sheets as of December 31, 2025 and 2024 F- 6 Consolidated Statements of Stockholders’ Equity for the Years Ended December 31, 2025, 2024 and 2023 F- 7 Consolidated Statements of Cash Flows for the Years Ended December 31, 2025, 2024 and 2023 F- 8 Notes to Consolidated Financial Statements F- 10 Schedule I—Parent Company Financial Information F- 62 ZEOLYST INTERNATIONAL Audited Financial Statements Report of Independent Auditors F- 66 Statements of Operations and Accumulated Earnings for the Years Ended December 31, 2025, 2024 and 2023 F- 68 Balance Sheets as of December 31, 202 5 and 202 4 F- 69 Statements of Changes in Partners’ Capital for the Years Ended December 31, 202 5 , 202 4 and 202 3 F- 70 Statements of Cash Flows for the Years Ended December 31, 202 5 , 202 4 and 202 3 F- 71 Notes to the Financial Statements F- 72 F-1 Table of Contents Report of Independent Registered Public Accounting Firm To the Board of Directors and Stockholders of Ecovyst Inc. Opinions on the Financial Statements and Internal Control over Financial Reporting We have audited the accompanying consolidated balance sheets of Ecovyst Inc. and its subsidiaries (the “Company”) as of December 31, 2025 and 2024, and the related consolidated statements of (loss) income, of comprehensive (loss) income, of stockholders’ equity and of cash flows for each of the three years in the period ended December 31, 2025, including the related notes and schedule I – parent company financial information as of December 31, 2025 and 2024 and for each of the three years in the period ended December 31, 2025 listed in the accompanying index (collectively referred to as the “consolidated financial statements”). We also have audited the Company’s internal control over financial reporting as of December 31, 2025, based on criteria established in Internal Control - Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO). In our opinion, the consolidated financial statements referred to above present fairly, in all material respects, the financial position of the Company as of December 31, 2025 and 2024, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2025 in conformity with accounting principles generally accepted in the United States of America. Also in our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, 2025, based on criteria established in Internal Control - Integrated Framework (2013) issued by the COSO. Basis for Opinions The Company’s management is responsible for these consolidated financial statements, for maintaining effective internal control over financial reporting, and for its assessment of the effectiveness of internal control over financial reporting, included in Management’s Annual Report on Internal Control over Financial Reporting appearing under Item 9A. Our responsibility is to express opinions on the Company’s consolidated financial statements and on the Company’s internal control over financial reporting based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB. We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audits to obtain reasonable assurance about whether the consolidated financial statements are free of material misstatement, whether due to error or fraud, and whether effective internal control over financial reporting was maintained in all material respects. Our audits of the consolidated financial statements included performing procedures to assess the risks of material misstatement of the consolidated financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the consolidated financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the consolidated financial statements. Our audit of internal control over financial reporting included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, and testing and evaluating the design and operating effectiveness of internal control based on the assessed risk. Our audits also included performing such other procedures as we considered necessary in the circumstances. We believe that our audits provide a reasonable basis for our opinions. Definition and Limitations of Internal Control over Financial Reporting A company’s internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. A company’s internal control over financial reporting includes those policies and procedures that (i) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (ii) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in accordance with authorizations of F-2 Table of Contents management and directors of the company; and (iii) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect on the financial statements. Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate. Critical Audit Matters The critical audit matter communicated below is a matter arising from the current period audit of the consolidated financial statements that was communicated or required to be communicated to the audit committee and that (i) relates to accounts or disclosures that are material to the consolidated financial statements and (ii) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the consolidated financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates. Carrying Value - Advanced Materials & Catalysts Disposal Group As described in Notes 1 and 4 to the consolidated financial statements, on September 10, 2025, the Company entered into a definitive agreement to sell its Advanced Materials & Catalysts business to Technip Energies N.V. for a purchase price of $556.0 million subject to certain adjustments including indebtedness, cash, working capital and transaction expenses. In the third quarter of 2025, the Advanced Materials & Catalysts business met the criteria for classification as held for sale and discontinued operations, as the sale represents a strategic shift that will have a major effect on the Company’s operations and financial results. As a result of the Advanced Materials & Catalysts business meeting held for sale criteria in the third quarter of 2025, the Company was required to measure the disposal group at the lower of its carrying value or fair value less costs to sell. As such, management performed an impairment analysis using a fair value estimate based on the agreed upon arm's length sales price resulting in the recognition of an impairment charge for assets classified as held for sale of $83.9 million during the quarter ended September 30, 2025. This impairment charge primarily consisted of a $49.6 million impairment charge to goodwill along with a $34.3 million valuation allowance for the estimated loss on sale. The Company completed the sale of its Advanced Materials & Catalysts business effective on December 31, 2025. The Company recognized a disposal loss of $33.0 million during the year ended December 31, 2025, which was comprised of the $34.3 million estimated loss recognized during the quarter ended September 30, 2025, and a gain of $1.3 million recognized upon the closing of the transaction. The carrying value of the net assets of the disposal group, net of cash, utilized in the calculation of the loss on sale as of December 31, 2025 was $577.0 million. The principal considerations for our determination that performing procedures relating to the carrying value of the Advanced Materials & Catalysts disposal group is a critical audit matter are a high degree of auditor effort in performing procedures and evaluating audit evidence related to the disposal group. Addressing the matter involved performing procedures and evaluating audit evidence in connection with forming our overall opinion on the consolidated financial statements. These procedures included testing the effectiveness of the controls related to management’s accounting for the discontinued operations of the Advanced Materials & Catalysts disposal group, including controls over determining the carrying value of the disposal group. These procedures also included, among others (i) reading the executed sale agreement and (ii) testing management’s process for identifying legal entities in the disposal group and classifying the related transactions between discontinued operations and continuing operations that informed management's determination of the carrying value of the Advanced Materials & Catalysts disposal group. /s/ PricewaterhouseCoopers LLP Philadelphia, Pennsylvania February 27, 2026 We have served as the Company’s auditor since 2015. F-3 Table of Contents ECOVYST INC. AND SUBSIDIARIES CONSOLIDATED STATEMENTS OF (LOSS) INCOME (in thousands, except share and per share amounts) Years ended December 31, 2025 2024 2023 Sales $ 723,515 $ 598,295 $ 584,845 Cost of goods sold 565,429 434,911 418,396 Gross profit 158,086 163,384 166,449 Selling, general and administrative expenses 66,016 65,391 60,535 Other operating expense, net 27,185 12,860 16,363 Operating income 64,885 85,133 89,551 Interest expense, net 34,203 36,488 31,697 Debt modification and extinguishment costs 5,538 4,560 — Other (income) expense, net ( 642 ) ( 1,120 ) 905 Income from continuing operations before income taxes 25,786 45,205 56,949 Provision (benefit) for income taxes 19,498 ( 299 ) 8,726 Net income from continuing operations 6,288 45,504 48,223 Net (loss) income from discontinued operations, net of tax ( 77,414 ) ( 52,156 ) 22,931 Net (loss) income $ ( 71,126 ) $ ( 6,652 ) $ 71,154 Net (loss) income per share: Basic income per share—continuing operations $ 0.05 $ 0.39 $ 0.41 Diluted income per share—continuing operations $ 0.05 $ 0.39 $ 0.40 Basic (loss) income per share—discontinued operations $ ( 0.67 ) $ ( 0.45 ) $ 0.19 Diluted (loss) income per share—discontinued operations $ ( 0.67 ) $ ( 0.44 ) $ 0.19 Basic (loss) income per share $ ( 0.62 ) $ ( 0.06 ) $ 0.60 Diluted (loss) income per share $ ( 0.61 ) $ ( 0.06 ) $ 0.60 Weighted average shares outstanding: Basic 115,291,879 116,719,437 118,367,214 Diluted 115,957,562 117,447,438 119,487,709 See accompanying notes to consolidated financial statements. F-4 Table of Contents ECOVYST INC. AND SUBSIDIARIES CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS) INCOME (in thousands) Years ended December 31, 2025 2024 2023 Net (loss) income $ ( 71,126 ) $ ( 6,652 ) $ 71,154 Other comprehensive income (loss), net of tax: Pension and postretirement benefits 983 855 1,120 Net loss from hedging activities ( 9,081 ) ( 2,644 ) ( 12,126 ) Foreign currency translation 18,776 ( 4,660 ) 4,056 Total other comprehensive income (loss) 10,678 ( 6,449 ) ( 6,950 ) Comprehensive (loss) income $ ( 60,448 ) $ ( 13,101 ) $ 64,204 See accompanying notes to consolidated financial statements. F-5 Table of Contents ECOVYST INC. AND SUBSIDIARIES CONSOLIDATED BALANCE SHEETS (in thousands, except share and per share amounts) December 31, 2025 2024 ASSETS Cash and cash equivalents $ 197,193 $ 131,390 Accounts receivable, net 85,313 53,204 Inventories, net 26,803 17,973 Derivative assets 1,312 6,532 Prepaid and other current assets 8,736 10,931 Current assets held for sale — 83,684 Total current assets 319,357 303,714 Property, plant and equipment, net 481,159 458,684 Goodwill 326,744 326,589 Other intangible assets, net 59,288 67,700 Right-of-use lease assets 37,935 33,082 Other long-term assets 36,495 37,342 Long-term assets held for sale — 575,210 Total assets $ 1,260,978 $ 1,802,321 LIABILITIES Current maturities of long-term debt $ — $ 8,730 Accounts payable 48,048 32,936 Operating lease liabilities—current 9,495 9,053 Accrued liabilities 63,272 39,825 Current liabilities held for sale — 24,582 Total current liabilities 120,815 115,126 Long-term debt, excluding current portion 392,581 852,099 Deferred income taxes 113,288 105,395 Operating lease liabilities—noncurrent 28,666 23,927 Other long-term liabilities 2,188 3,146 Long-term liabilities held for sale — 2,168 Total liabilities 657,538 1,101,861 Commitments and contingencies (Note 22) EQUITY Common stock ($ 0.01 par); authorized shares 450,000,000 ; issued shares 140,872,846 and 140,872,846 on December 31, 2025 and 2024, respectively; outstanding shares 111,805,102 and 116,534,803 on December 31, 2025 and 2024, respectively 1,409 1,409 Preferred stock ($ 0.01 par); authorized shares 50,000,000 ; no shares issued or outstanding on December 31, 2025 and 2024, respectively — — Additional paid-in capital 1,108,525 1,106,792 Accumulated deficit ( 248,634 ) ( 177,508 ) Treasury stock, at cost; shares 29,067,744 and 24,338,043 on December 31, 2025 and 2024, respectively ( 261,131 ) ( 222,826 ) Accumulated other comprehensive income (loss) 3,271 ( 7,407 ) Total equity 603,440 700,460 Total liabilities and equity $ 1,260,978 $ 1,802,321 See accompanying notes to consolidated financial statements. F-6 Table of Contents ECOVYST INC. AND SUBSIDIARIES CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY (in thousands, except share data) Shares of Common stock Common stock Additional paid-in capital Accum. deficit Shares of Treasury stock Treasury stock, at cost Accum. other comp. income (loss) Total Balance, December 31, 2022 139,571,272 $ 1,396 $ 1,091,475 $ ( 242,010 ) ( 17,385,034 ) $ ( 149,624 ) $ 5,992 $ 707,229 Net income — — — 71,154 — — — 71,154 Other comprehensive loss — — — — — — ( 6,950 ) ( 6,950 ) Repurchases of common shares — — — — ( 7,541,494 ) ( 78,718 ) — ( 78,718 ) Tax withholdings on equity award vesting — — — — ( 315,635 ) ( 3,372 ) — ( 3,372 ) Excise tax on repurchase of common shares — — — — — ( 638 ) — ( 638 ) Stock compensation expense — — 16,252 — — — — 16,252 Shares issued under equity incentive plan, net of forfeitures 1,172,773 11 ( 5,146 ) — 615,013 5,642 — 507 Balance, December 31, 2023 140,744,045 1,407 1,102,581 ( 170,856 ) ( 24,627,150 ) ( 226,710 ) ( 958 ) 705,464 Net loss — — — ( 6,652 ) — — — ( 6,652 ) Other comprehensive loss — — — — — — ( 6,449 ) ( 6,449 ) Repurchases of common shares — — — — ( 552,081 ) ( 5,010 ) — ( 5,010 ) Tax withholdings on equity award vesting — — — — ( 128,801 ) ( 1,218 ) — ( 1,218 ) Stock compensation expense — — 14,037 — — — — 14,037 Shares issued under equity incentive plan, net of forfeitures 128,801 2 ( 9,826 ) — 969,989 10,112 — 288 Balance, December 31, 2024 140,872,846 1,409 1,106,792 ( 177,508 ) ( 24,338,043 ) ( 222,826 ) ( 7,407 ) 700,460 Net loss — — — ( 71,126 ) — — — ( 71,126 ) Other comprehensive income — — — — — — 10,678 10,678 Repurchases of common shares — — — — ( 5,752,285 ) ( 47,501 ) — ( 47,501 ) Tax withholdings on equity award vesting — — — — ( 189,446 ) ( 1,477 ) — ( 1,477 ) Excise tax on repurchase of common shares — — — — — ( 392 ) — ( 392 ) Stock compensation expense — — 12,316 — — — — 12,316 Shares issued under equity incentive plan, net of forfeitures — — ( 10,583 ) — 1,212,030 11,065 — 482 Balance, December 31, 2025 140,872,846 $ 1,409 $ 1,108,525 $ ( 248,634 ) ( 29,067,744 ) $ ( 261,131 ) $ 3,271 $ 603,440 See accompanying notes to consolidated financial statements. F-7 Table of Contents ECOVYST INC. AND SUBSIDIARIES CONSOLIDATED STATEMENTS OF CASH FLOWS (in thousands) Years ended December 31, 2025 2024 2023 Cash flows from operating activities: Net income $ ( 71,126 ) $ ( 6,652 ) $ 71,154 Net income (loss) from discontinued operations 77,414 52,156 ( 22,931 ) Net income from continuing operations 6,288 45,504 48,223 Adjustments to reconcile net income to net cash provided by operating activities: Depreciation 67,806 59,863 55,345 Amortization 10,791 10,685 10,685 Amortization of deferred financing costs and original issue discount 1,212 1,384 1,733 Debt extinguishment costs 4,578 90 — Deferred income tax provision (benefit) 32,206 ( 5,009 ) ( 10,382 ) Net loss on asset disposals 5,371 2,254 4,101 Stock compensation 9,746 11,126 12,984 Other, net ( 5,356 ) ( 12,904 ) ( 6,223 ) Working capital changes that provided (used) cash: Receivables ( 22,118 ) 6,236 ( 2,433 ) Inventories ( 5,571 ) ( 4,544 ) ( 107 ) Prepaids and other current assets ( 962 ) 2,795 178 Accounts payable 15,531 1,164 1,713 Accrued liabilities ( 1,416 ) ( 14,821 ) ( 15,270 ) Net cash provided by operating activities, continuing operations 118,106 103,823 100,547 Net cash provided by operating activities, discontinued operations 22,199 46,067 37,050 Net cash provided by operating activities 140,305 149,890 137,597 Cash flows from investing activities: Purchases of property, plant and equipment ( 70,410 ) ( 55,594 ) ( 59,039 ) Proceeds from business divestitures, net of cash transferred 568,427 — — Business combinations ( 41,480 ) — — Net cash provided by (used in) investing activities, continuing operations 456,537 ( 55,594 ) ( 59,039 ) Net cash used in investing activities, discontinued operations ( 21,125 ) ( 17,859 ) ( 6,296 ) Net cash provided by (used in) investing activities 435,412 ( 73,453 ) ( 65,335 ) F-8 Table of Contents Years ended December 31, 2025 2024 2023 Cash flows from financing activities: Draw down of revolving credit facilities — — 14,500 Repayments of revolving credit facilities — — ( 14,500 ) Issuance of long-term debt, net of original issue discount and financing fees 870,817 870,817 — Repayments of long-term debt ( 1,344,548 ) ( 879,683 ) ( 9,000 ) Repurchases of common shares ( 46,948 ) ( 5,010 ) ( 78,717 ) Tax withholdings on equity award vesting ( 1,477 ) ( 1,218 ) ( 3,372 ) Other, net 460 210 438 Net cash used in financing activities, continuing operations ( 521,696 ) ( 14,884 ) ( 90,651 ) Net cash used in financing activities, discontinued operations ( 3,264 ) ( 2,957 ) ( 2,847 ) Net cash used in financing activities ( 524,960 ) ( 17,841 ) ( 93,498 ) Effect of exchange rate changes on cash and cash equivalents 423 ( 948 ) ( 1,319 ) Net change in cash and cash equivalents 51,180 57,648 ( 22,555 ) Cash and cash equivalents at beginning of period 146,013 88,365 110,920 Cash and cash equivalents at end of period 197,193 146,013 88,365 Less: cash and cash equivalents of discontinued operations — ( 14,623 ) ( 15,715 ) Cash and cash equivalents at end of period of continuing operations $ 197,193 $ 131,390 $ 72,650 For supplemental cash flow disclosures, see Note 24. See accompanying notes to consolidated financial statements. F-9 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) 1. Background and Basis of Presentation: Description of Business Ecovyst Inc. and subsidiaries (the “Company” or “Ecovyst”) is a leading provider of virgin and regenerated sulfuric acid products and services. The Company supports customers through its strategically located network of manufacturing facilities. The Company believes that its products and services contribute to improving the sustainability of the environment. The Company has a uniquely positioned specialty business, Ecoservices, which provides sulfuric acid recycling to the North American refining industry for the production of alkylate and provides high quality and high strength virgin sulfuric acid for mining and industrial applications. Ecoservices also provides chemical waste handling and treatment services, as well as ex-situ catalyst activation services for the refining and petrochemical industry. The Company’s regeneration services product group typically experiences seasonal fluctuations as a result of higher demand for gasoline products in the summer months and lower demand in the winter months. These demand fluctuations result in higher sales and working capital requirements in the second and third quarters. Basis of Presentation On September 10, 2025, the Company entered into a definitive agreement to sell its Advanced Materials & Catalysts busines s, which includes the Company’s investment in affiliated companies, Zeolyst International and Zeolyst C.V. (collectively, the “Zeolyst Joint Venture”) to Technip Energies N.V. On December 31, 2025, the Company completed the sale of its Advanced Materials & Catalysts business for a purchase price of $ 556,000 , subject to certain purchase price adjustments as set forth in the agreement. The financial results of this business are presented as discontinued operations in the consolidated financial statements. See Note 4 to these consolidated financial statements for further information on this transaction. The notes to the consolidated financial statements, unless otherwise indicated, are on a continuing operations basis. 2. Summary of Significant Accounting Policies: Principles of Consolidation. The consolidated financial statements include the accounts of the Company and its controlled subsidiaries. All intercompany transactions have been eliminated. Investments in Affiliated Companies. Investments in affiliated companies are accounted for using the equity method of accounting if the investment provides the Company with the ability to exercise significant influence, but not control, over the investee. Significant influence is generally deemed to exist if the Company’s ownership interest in the voting stock of the investee ranges between 20% and 50%, although other factors, such as representation on the investee’s board of directors and the impact of commercial arrangements, are considered in determining whether the equity method of accounting is appropriate. Under the equity method of accounting, the investments in equity-method investees are recorded in the consolidated balance sheets as investments in affiliated companies, and the Company’s share of the investees’ earnings or losses, together with other than temporary impairments in value, is recorded as equity in net income from affiliated companies in the consolidated statements of income. Any differences between the Company’s cost of an equity method investment and the underlying equity in the net assets of the investment, such as fair value step-ups resulting from acquisitions, are accounted for according to their nature and impact the amounts recognized as equity in net income from affiliated companies in the consolidated statements of income. Foreign Currency Translation. All assets and liabilities of foreign subsidiaries and affiliated companies are translated to U.S. dollars using exchange rates in effect at the balance sheet date. Income and expense items are translated at average exchange rates during the year. Adjustments resulting from translation of the balance sheets and statements of income are included in stockholders’ equity as part of accumulated other comprehensive income (loss) (“AOCI”), and are included in earnings only upon the sale or liquidation of the underlying foreign subsidiary or affiliated company. F-10 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) During the fourth quarter of 2025, the Company completed the sale of its Advanced Materials & Catalysts business, which included all of the Company’s foreign subsidiaries and affiliated companies. Historical foreign currency translation adjustments, which were previously recognized in AOCI, were fully reclassified from equity to net (loss) income from discontinued operations, net of tax in the consolidated income statement for the year ended December 31, 2025. See Note 8 to these consolidated financial statements for further information. Cash and Cash Equivalents. Cash and cash equivalents include highly liquid investments with original terms to maturity of 90 days or less from the time of purchase. Restricted Cash. Restricted cash, which is restricted as to withdrawal or usage, is classified separately from cash and cash equivalents on the Company’s consolidated balance sheets. The Company had no restricted cash balances as of December 31, 2025 and 2024. Accounts Receivable and Allowance for Credit Losses. Trade accounts receivable are recorded at the invoiced amount and do not bear interest. The allowance for credit losses is the Company’s best estimate of the amount of probable credit losses in its existing accounts receivable and is reviewed during each reporting period over their contractual life. The Company recognizes an allowance for credit losses based on historical collection experience, current regional economic and market conditions, the aging of accounts receivable and assessments of current creditworthiness of customers. Account balances are charged against the allowance when the Company believes it is probable that the associated receivables will not be recovered. If the financial condition of the Company’s customers were to deteriorate resulting in an impairment of their ability to make payments, additional allowances may be required. The Company does not have any off-balance sheet credit exposure related to its customers. The Company’s allowance for credit losses was not material as of December 31, 2025 and 2024. Inventories. All inventories are stated at the lower of cost or net realizable value and valued using the weighted average cost or first-in, first-out (“FIFO”) methods. Property, Plant and Equipment. Property, plant and equipment are carried at cost and include expenditures for new facilities, major renewals and betterments. The Company capitalizes the cost of furnace rebuilds as part of property, plant and equipment. Maintenance, repairs and minor renewals are charged to expense as incurred. The Company capitalizes certain internal costs associated with the implementation of purchased software. When property, plant and equipment is retired or otherwise disposed of, the net carrying amount is eliminated with any gain or loss on disposition recognized in earnings at that time. Depreciation is provided on the straight-line method based on the estimated useful lives of the assets, which generally range from 15 to 33 years for buildings and improvements and 3 to 10 years for machinery and equipment. Leasehold improvements are depreciated using the straight-line method based on the shorter of the useful life of the improvement or remaining lease term. The Company capitalizes the interest cost associated with the development and construction of significant new plant and equipment and depreciates that amount over the lives of the related assets. Capitalized interest recorded during the years ended December 31, 2025, 2024 and 2023 was $ 1,664 , $ 1,008 and $ 1,964 , respectively. Lea ses . The Company has operating and finance lease agreements with remaining lease terms as of December 31, 2025 of up to 16 years, including leases of land, buildings, railcars, vehicles, manufacturing equipment and general office equipment. Some leases include options to terminate or extend for one or more years. These options are incorporated in the Compan y’s lease term when it is reasonably certain that the option will be exercised. Some leases include options to purchase, which the Company assesses under the guidance to determine if these leases should be classified as finance lease agreements. When the Company enters into an arrangement, at inception, the Company determines if the arrangement contains a lease and whether that lease meets the classification criteria of a finance or operating lease. Some of the Company’s lease arrangements contain lease components (e.g. minimum rent payments) and non-lease components (e.g. maintenance). The Company accounts for the lease and non-lease components separately based on the estimated standalone price of each component. Certain of the Company’s lease agreements include rental payments that are adjusted periodically for an index or rate and these are initially measured using the index or rate in effect at the commencement date. Variable lease expense is recognized in the period in which the obligation for those payments is F-11 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) incurred. The Company’s lease agreements do not contain any material residual value guarantees or material restrictive covenants. The Company recognizes a right-of-use lease asset and lease liability at the lease commencement date based on the present value of the remaining lease payments over the lease term. The Company assesses its leasing arrangements to determine the rate implicit in the lease arrangement. Historically, the Company’s leasing arrangements do not contain the information necessary to determine the rate implicit in the lease. As such, the Company utilizes its incremental borrowing rate over the relevant lease term, which is the rate of interest that it would have to pay to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. The incremental borrowing rate is determined at the lease commencement date and is developed utilizing a readily available market interest rate curve adjusted for the Company’s credit quality. The Company has elected to use a portfolio approach to apply its incremental borrowing rate to individual leases based on lease term and geographic jurisdiction. Short-term leases, which have an initial term of twelve months or less, are not recorded on the Company’s balance sheet. Lease expense for operating leases is recognized on a straight-line basis over the lease term. Lease expense for financing leases is bifurcated into two components, with the amortization expense component of the right-of-use asset recognized on a straight-line basis and the interest expense component recognized using the effective interest method over the lease term. The amortization expense component of the right-of-use lease asset is included in cost of goods sold and in selling, general and administrative expenses and the interest expense component is included in interest expense, net on the consolidated statements of (loss) income. Spare Parts. Spare parts are maintained by the Company’s facilities to keep machinery and equipment in working order. Spare parts are capitalized and included in other long-term assets. Spare parts are measured at cost and are not depreciated or expensed until utilized; however, reserves may be provided on aged spare parts. When a spare part is utilized as part of an improvement to property, plant and equipment, the carrying value is depreciated over the applicable life once placed in service. Otherwise, the spare part is expensed and charged as a cost of production when utilized. Goodwill and Intangible Assets. Goodwill is an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. The Company is required to test goodwill associated with its reporting unit for impairment at least annually and whenever events or circumstances indicate that it is more likely than not that goodwill may be impaired. The Company completed its annual goodwill impairment test as of October 1. Goodwill is tested for impairment at the reporting unit level. In performing tests for goodwill impairment, the Company is able to use its discretion to first perform an optional qualitative assessment about the likelihood of the carrying value of a reporting unit exceeding its fair value. The qualitative assessment need not be applied to all reporting units. If the Company determines that it is more likely than not that the fair value of a reporting unit is less than its carrying amount based on the qualitative assessment, the Company will perform a quantitative goodwill impairment test to identify the potential goodwill impairment and measure the amount of the goodwill impairment loss, if any, to be recognized for that reporting unit. For the annual assessments in 2025 and 2024, the Company bypassed the option to perform the qualitative assessment and proceeded directly to performing the quantitative goodwill impairment test at the reporting unit level. The quantitative test identifies both the potential existence of impairment and the amount of impairment loss. In applying the quantitative test, the Company calculates and compares the reporting unit’s estimated fair value to its carrying value, including goodwill. If the fair value of a reporting unit exceeds its carrying value, goodwill is not impaired. If the carrying value of a reporting unit exceeds its fair value, an impairment loss is recognized for the amount by which the carrying value exceeds the reporting unit’s fair value. An impairment loss cannot exceed the carrying value of goodwill assigned to a reporting unit and the loss establishes a new basis in the goodwill. Subsequent reversal of an impairment loss is not permitted. For intangible assets other than goodwill, definite-lived intangible assets are amortized over their respective estimated useful lives. Intangible assets with indefinite lives are not amortized, but rather are tested for impairment at least annually or more frequently if events occur or circumstances change that would more likely than not reduce the fair value of the intangible asset below its carrying amount. The Company tests its indefinite-lived intangible assets as of October 1 of each year in conjunction with its annual goodwill impairment test. F-12 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) Impairment Assessment of Long-Lived Assets. The Company performs an impairment review of property, plant and equipment and definite-lived intangible assets when facts and circumstances indicate that the carrying value of an asset or asset group may not be recoverable from its undiscounted future cash flows. When evaluating long-lived assets for impairment, if the carrying amount of an asset or asset group is found not to be recoverable, a potential impairment loss may be recognized. An impairment loss is measured by comparing the carrying amount of the asset or asset group to its fair value. Fair value is determined using quoted market prices when available, or other techniques including discounted cash flows. The Company’s estimates of future cash flows involve assumptions concerning future operating performance, economic conditions and technological changes that may affect the future useful lives of the assets. Long-lived assets classified as held for sale are measured at the lower of carrying amount or fair value less cost to sell. A loss is recognized for any initial adjustment required to reduce the carrying amount to the fair value less cost to sell in the period the held for sale criteria are met. The fair value less cost to sell is assessed each reporting period that the asset or asset group remains classified as held for sale. Gains or losses not previously recognized resulting from the sale of an asset group will be recognized on the date of sale. Derivative Financial Instruments. The Company utilizes certain derivative financial instruments to enhance its ability to manage risk, including exposure to interest rate fluctuations that exist as part of ongoing business operations. Derivative instruments are entered into for periods consistent with the related underlying exposures and do not constitute positions independent of those exposures. All derivatives are recognized on the consolidated balance sheets at fair value. The Company may designate a derivative as a hedge of the fair value of a recognized asset or liability or of an unrecognized firm commitment (fair value hedge), a hedge of a forecasted transaction or the variability of cash flows to be received or paid related to a recognized asset or liability (cash flow hedge), a foreign currency fair-value or cash-flow hedge (foreign currency hedge), or a hedge of a net investment in a foreign operation (net investment hedge). The Company’s hedging strategies include derivatives designated as cash flow hedges. Changes in the fair value of a derivative that is highly effective and that is designated and qualifies as a cash flow hedge are recorded in other comprehensive income and subsequently reclassified into earnings in the same period(s) in which the hedged transaction affects earnings. Changes in the fair value of a derivative that is highly effective and that is designated and qualifies as a hedge of a net investment in a foreign operation are recorded in the foreign currency translation adjustment account within AOCI, where the associated gains and losses will remain until such time that the hedged net investment (foreign subsidiary) is sold or liquidated. Changes in the fair value of a derivative that is not designated or does not qualify as a hedge are recorded in the same line on the consolidated statements of (loss) income as the changes in the fair value from the items being hedged. Cash flows from derivative instruments are reported in the same cash flow category as the cash flows from the items being hedged. The Company formally documents all relationships between hedging instruments and hedged items, as well as its risk-management objective and strategy for undertaking various hedge transactions. The Company also formally assesses whether each hedging relationship is highly effective in achieving offsetting changes in fair values or cash flows of the hedged item during the period, both at the inception of the hedge and on an ongoing basis. If it is determined that a derivative is not highly effective as a hedge, or if a derivative ceases to be a highly-effective hedge, hedge accounting is discontinued with respect to that derivative prospectively. Fair Value Measurements. The Company measures fair value using the guidelines under U.S. generally accepted accounting principles (“GAAP”). An asset’s fair value is defined as the price at which the asset could be exchanged in a current transaction between market participants. A liability’s fair value is defined as the amount that would be paid to transfer the liability to a market participant, not the amount that would be paid to settle the liability with the creditor. The carrying values of cash, accounts receivable, accounts payable and accrued liabilities approximate fair value due to the short-term nature of these items. See Note 7 to these consolidated financial statements for further information regarding the application of fair value measurements on the Company’s recurring and non-recurring bases and Note 16 regarding the fair value of debt. F-13 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) Treasury Stock. The Company records repurchases of its common stock for treasury at cost. Upon the reissuance of the Company’s common stock from treasury, differences between the proceeds from reissuance and the average cost of the treasury stock are credited or charged to capital in excess of par value to the extent of prior credits related to the reissuance of treasury stock. If no such credits exist, the differences are charged to retained earnings. See Note 8 of these consolidated financial statements for further information regarding the Company’s treasury stock repurchases. Revenue Recognition. In determining the appropriate amount of revenue to be recognized as the Company fulfills its obligations under its agreements, the Company performs the following steps: (i) identification of the contract with the customer; (ii) determination of whether the promised goods or services are performance obligations, including whether they are distinct in the context of the contract; (iii) measurement of the transaction price; (iv) allocation of the transaction price to the performance obligations based on estimated selling prices; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. The Company identifies a contract when an agreement with a customer creates legally enforceable rights and obligations, which occurs when a contract has been approved by both parties, the parties are committed to perform their respective obligations, each party’s rights and payment terms are clearly identified, commercial substance exists and it is probable that the Company will collect the consideration to which it is entitled. The Company may offer rebates to customers who have reached a specified volume of optional purchases. The Company recognizes rebates given to customers as a reduction of revenue based on an allocation of the cost of honoring rebates earned and claimed to each of the underlying revenue transactions that result in progress by the customer toward earning the rebate. Rebates are recognized at the time revenue is recorded. The Company measures the rebate obligation based on the estimated amount of sales that will result in a rebate at the adjusted sales price per the respective sales agreement. Shipping and Handling. Amounts billed to a customer in a sale transaction related to shipping and handling, if any, represent revenues earned for the goods provided and are classified as revenue. Costs related to shipping and handling of products shipped to customers are classified as cost of goods sold. See Note 6 of these consolidated financial statements for disclosures regarding the recognition of revenue for shipping and handling costs that are billed to customers. Income Taxes. The Company operates within multiple state taxing jurisdictions and is subject to tax filing requirements and potential audits within these jurisdictions. The Company uses the asset and liability method in accounting for income taxes. Deferred tax assets and liabilities are recorded for temporary differences between the tax basis of assets and liabilities and their reported amounts in the financial statements, using statutory tax rates in effect for the year in which the differences are expected to reverse. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the results of operations in the period that includes the enactment date. The Company evaluates its deferred tax assets each period to ensure that estimated future taxable income will be sufficient in character (e.g., capital gain versus ordinary income treatment), amount and timing, to result in their realizability. A valuation allowance is recorded to reduce the carrying amounts of deferred tax assets, unless it is more likely than not that those assets will be realized. The Company recognizes a financial statement benefit for positions taken for tax return purposes when it will be more likely than not (i.e. greater than 50%) that the positions will be sustained upon tax examination, based solely on the technical merits of the tax positions. Otherwise, no tax benefit is recognized. The tax benefits recognized are measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate settlement. The Company recognizes potential accrued interest and penalties related to unrecognized tax benefits as a component of income tax expense. Tax examinations are often complex as tax authorities may disagree with the treatment of items reported by the Company and may require several years to resolve. These accrued liabilities represent a provision for taxes that are reasonably expected to be incurred on the basis of available information but which are not certain. Environmental Expenditures. Environmental expenditures that pertain to current operations or to future revenues are expensed or capitalized consistent with the Company’s capitalization policy for property, plant and equipment. Expenditures that result from the remediation of an existing condition caused by past operations and that do not contribute to current or future revenues are expensed. Liabilities are recognized for remedial activities when the remediation is probable and the cost can be reasonably estimated. Recoveries of expenditures for environmental F-14 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) remediation are recognized as assets only when recovery is deemed probable. See Note 22 to these consolidated financial statements for further information regarding commitments and contingencies. Deferred Financing Costs. Financing costs incurred in connection with the issuance of long-term debt are deferred and presented as a direct reduction from the related debt instruments on the Company’s consolidated balance sheets. Deferred financing costs are amortized as interest expense using the effective interest method over the respective terms of the associated debt instruments. Stock-Based Compensation. The Company applies the fair value based method to account for stock options, restricted stock awards, restricted stock units and performance stock units issued in connection with its equity incentive plans. Stock-based compensation expense is recognized on a straight-line basis over the vesting periods of the respective awards, and the Company accounts for forfeitures of equity incentive awards as they occur. In connection with the vesting of restricted stock awards, restricted stock units and performance stock units, shares of common stock may be delivered to the Company by employees to satisfy withholding tax obligations at the instruction of the employee award holders. These transactions, when they occur, are accounted for as stock repurchases by the Company, with the shares returned to treasury stock at a cost representing the payment by the Company of the tax obligations on behalf of the employees in lieu of shares for the vesting event. See Note 20 to these consolidated financial statements regarding compensation expense associated with the Company’s equity incentive awards. Pensions and Postretirement Benefits. The Company sponsors two funded defined benefit pension plans that cover certain employees. Benefits for the plans are generally based on average final pay and years of service. The Company’s funding policy is to fund the minimum required contributions consistent with statutory requirements based on actuarial computations utilizing the projected unit credit method of calculation. The pension plans’ assets include equity and fixed income securities. Certain assumptions are made regarding the occurrence of future events affecting pension costs, such as mortality, withdrawal, disa blement and retirement, changes in compensation and benefits, and discount rates to reflect the time value of money. The major elements in determining pension income and expense are pension liability discount rates and the expected return on plan assets. The Company references rates of return on high quality, fixed income investments when estimating the discount rate, and the expected period over which payments will be made based upon historical experience. The long-term rate of return used to calculate the expected return on plan assets is the average rate of return estimated to be earned on invested funds for providing pension benefits. In addition to pension benefits, the Company provides certain health care benefits for employees who meet age, participation and length of service requirements at retirement. The Company uses explicit assumptions using the best estimates available of the plan’s future experience. Principal actuarial assumptions include: discount rates, present value factors, retirement age, participation rates, mortality rates, cost trend rates, Medicare reimbursement rates and per capita claims cost by age. Current interest rates as of the measurement date are used for discount rates in present value calculations. The Company also has defined contribution plans covering domestic employees of the Company and certain subsidiaries. Contingencies. Certain conditions may exist as of the date the financial statements are issued, which may result in a loss to the Company but which will only be resolved when one or more future events occur or fail to occur. The Company’s management and its legal counsel assess such contingent liabilities, and such assessment inherently involves an exercise of judgment. In assessing loss contingencies related to legal proceedings that are pending against the Company or unasserted claims that may result in such proceedings, the Company and legal counsel evaluate the perceived merits of any legal proceedings or unasserted claims as well as the perceived merits of the amount of relief sought or expected to be sought therein. If the assessment of a contingency indicates that it is probable that a loss has been incurred and the amount of the liability can be estimated, then the estimated liability is accrued in the Company’s financial statements. If the assessment indicates that a loss contingency is not probable, but is reasonably possible, or is probable but cannot be estimated, then the nature of the contingent liability, together with an estimate of the range of possible loss if determinable and material, would be disclosed. Loss contingencies considered remote are generally not disclosed unless they involve guarantees, in which case the nature of the guarantee would be disclosed, including the F-15 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) approximate term, how the guarantee arose, and the events or circumstances that would require the guarantor to perform under the guarantee. Use of Estimates. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Correction of Errors . Net (loss) income from discontinued operations, net of tax for the year ended December 31, 2024 included an adjustment of $ 1,025 related to the Advanced Materials & Catalysts inventory valuation and an adjustment of $ 939 for the Company’s equity in net income of affiliated companies related to revised Zeolyst International results for the year ended December 31, 2023 and 2022. The total 2024 net benefit of $ 1,964 from these adjustments was not material to the consolidated financial statements for prior interim or annual periods. 3. New Accounting Standards: Accounting Standards Recently Adopted In December 2023, the Financial Accounting Standards Board (“FASB”) issued guidance to improve disclosures related to incomes taxes. This new guidance requires public business entities (“PBEs”) to disaggregate information on the effective tax rate reconciliation and income taxes paid to provide greater transparency. PBEs will be required to provide additional information in specified categories related to effective tax rate reconciliation in tabular form and provide income taxes paid by jurisdictions, with further disaggregation needed if amounts exceed 5% of the total. The new guidance is effective for fiscal years beginning after December 15, 2024. The Company has applied the guidance prospectively for the fiscal year ended December 31, 2025. Accounting Standards Not Yet Adopted In July 2025, FASB issued guidance related to the estimation of expected credit losses for current accounts receivable and current contract assets that arise from transactions accounted for under ASC 606 . This new guidance introduces a practical expedient for entities that assumes that current conditions as of the balance sheet date do not change for the remaining life of the asset. The new guidance is effective for fiscal years beginning after December 15, 2025 and interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the impact of this guidance. In November 2024, FASB issued guidance requiring PBEs to disclose additional information on the nature of certain expenses presented in the income statement. The new guidance requires tabular disclosure of significant expense categories and qualitative descriptions for amounts not disaggregated from relevant expense categories. PBEs are required to define selling expenses and disaggregate the components. The new guidance is effective for fiscal years beginning after December 15, 2026 and interim periods within fiscal years beginning after December 15, 2027, with early adoption permitted. The requirements must be applied prospectively however PBEs have the option to apply the guidance retrospectively. The disclosure will be implemented as required for the fiscal year ended December 31, 2027. The Company is currently evaluating the impact of this guidance. F-16 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) 4. Divestitures: Advanced Materials & Catalysts On September 10, 2025, the Company entered into a definitive agreement to sell its Advanced Materials & Catalysts business, which includes the Zeolyst Joint Venture, to Technip Energies N.V. (the “Buyer”) for a purchase price of $ 556,000 subject to certain adjustments including indebtedness, cash, working capital and transaction expenses, as set forth in the definitive agreement (the “Advanced Materials & Catalysts Sale”). The Company completed the sale of its Advanced Materials & Catalysts business effective on December 31, 2025. The net cash proceeds to the Company from the sale were $ 568,427 after certain customary adjustments for indebtedness, working capital and cash at the closing of the transaction. The Company classified the proceeds within net cash provided by (used in) investing activities, continuing operations in the consolidated statements of cash flows and used a portion of the net proceeds from the sale to pay down debt. In the third quarter of 2025, the Advanced Materials & Catalysts business met the criteria set forth in Accounting Standards Codification 205-20, Presentation of Financial Statements – Discontinued Operations (“ASC 205-20”) , as the sale represents a strategic shift that will have a major effect on the Company’s operations and financial results. As a result, the Company’s consolidated financial statements for all periods presented reflect the Advanced Materials & Catalysts business as a discontinued operation. The Advanced Materials & Catalysts business historically represented a reportable segment of the Company. As a result of the Advanced Materials & Catalysts business meeting held for sale criteria in the third quarter of 2025, the Company was required to measure the disposal group at the lower of its carrying value or fair value less costs to sell. As such, the Company performed an impairment analysis using a fair value estimate based on the agreed upon arm's length sales price resulting in the recognition of an impairment charge for assets classified as held for sale of $ 83,898 during the quarter ended September 30, 2025. This impairment charge consisted of a $ 49,636 impairment charge to goodwill along with a $ 34,262 valuation allowance for the estimated loss on sale. The Company recognized a disposal loss of $ 32,967 during the year ended December 31, 2025, which was comprised of the $ 34,262 estimated loss recognized during the quarter ended September 30, 2025, and a gain of $ 1,295 recognized upon the closing of the transaction (see below), which was included in net (loss) income from discontinued operations, net of tax on the consolidated statements of (loss) income for the respective periods. During the year ended December 31, 2025, the Company incurred transaction costs of $ 18,105 which is included in net (loss) income from discontinued operations, net of tax. Transaction costs consist of $ 5,906 incurred prior to meeting held for sale classification and included in other operating expense, net and $ 12,199 included in loss on sale, before taxes during the year ended December 31, 2025. In connection with the sale of the Advanced Materials & Catalysts business and the related loss, as noted above, the Company has recognized tax expense of $ 15,868 within net (loss) income from discontinued operations, net of tax on the consolidated statements of (loss) income. The calculation of the tax gain on the sale is inherently based on estimates which might ultimately be challenged by the taxing authorities. F-17 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) The following is a reconciliation of the loss recorded on the sale: Sale price $ 556,000 Less: Cash transferred ( 12,073 ) Add: Working capital and other customary closing adjustments 24,500 Proceeds from sale, net of cash transferred and net working capital and customary closing adjustments 568,427 Less: Estimated future net working capital and customary closing and other adjustments (1) ( 5,081 ) Proceeds from sale, net of cash transferred and estimated net working capital and customary closing adjustments 563,346 Less: Carrying value of net assets divested, net of cash 577,039 Direct costs to sell 12,199 Accumulated other comprehensive loss reclassification adjustment, foreign currency translation 7,075 Loss on sale, before taxes $ ( 32,967 ) (1) Certain working capital and other adjustments are to be finalized over a defined period from the close of sale. Any resulting revisions will be settled in cash, with an offsetting impact recognized in loss on sale. The following table summarizes the results of discontinued operations for the years ended December 31, 2025, 2024 and 2023: Years ended December 31, 2025 2024 2023 Sales $ 96,890 $ 106,198 $ 106,273 Cost of goods sold 61,997 68,060 74,757 Gross profit 34,893 38,138 31,516 Selling, general and administrative expenses 18,828 18,485 18,680 Goodwill impairment charge (1) 49,636 — — Other operating expense, net (2) 8,311 6,692 5,737 Loss on sale, before taxes 32,967 — — Operating (loss) income ( 74,849 ) 12,961 7,099 Equity in net (income) from affiliated companies ( 19,381 ) ( 15,112 ) ( 30,624 ) Impairment of investment of affiliated companies (3) — 65,000 — Interest expense, net (4) 10,595 12,938 13,033 Other expense (income), net 466 362 ( 300 ) (Loss) income from discontinued operations before income taxes ( 66,529 ) ( 50,227 ) 24,990 Provision for income taxes 10,885 1,929 2,059 Net (loss) income from discontinued operations, net of tax $ ( 77,414 ) $ ( 52,156 ) $ 22,931 (1) As a result of the Advanced Materials & Catalysts business meeting held for sale criteria in the third quarter of 2025, the Company was required to measure the disposal group at the lower of its carrying values or fair values less costs to sell. As such, the Company performed an impairment analysis using a fair value estimate based on the agreed upon arm's length sales price resulting in the recognition of a goodwill impairment charge of 49,636 in the third quarter of 2025 related to the Advanced Materials & Catalysts business. F-18 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) (2) As part of the annual goodwill impairment test in 2024, the Company recognized an impairment charge of $ 3,900 within this line item related to the Advanced Materials & Catalysts in-process research and development intangible asset upon the conclusion that the associated project could no longer support the valuation due to extended time to commercialization and reductions in associated forecasted revenues. (3) The disposal group’s investments in affiliated companies balance as of December 31, 2025 and 2024 includes net purchase accounting fair value adjustments of $ 153,444 and $ 155,138 , respectively, related to a historical business combination consisting primarily of goodwill and intangible assets such as customer relationships, technical know-how and trade names. Equity in net income from affiliates is net of $ 1,694 , $ 3,761 and $ 6,403 of amortization expense related to purchase accounting fair value adjustments for the years ended December 31, 2025, 2024 and 2023, respectively. During the year ended December 31, 2024, the Company recognized a $ 65,000 other than temporary impairment charge on its investment in the Zeolyst Joint Venture to reduce the carrying value of the Company’s investment to its estimated fair value. This impairment was an adjustment to the goodwill and trade name components of the purchase accounting fair value adjustments recorded as a result of the historical business combination. (4) The closing of the transaction triggered the Company’s obligation to provide partial repayment under its Term Loan Credit Agreement, dated January 30, 2025 (the “2025 Term Loan Facility”). As such, interest expense has been allocated to discontinued operations on the basis of the Company’s mandatory partial repayment of $ 161,500 of the 2025 Term Loan Facility due June 12, 2031. F-19 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) The following table summarizes the assets and liabilities of discontinued operations as of December 31, 2024: December 31, 2024 ASSETS Cash and cash equivalents $ 14,623 Accounts receivables, net 24,733 Inventories, net 39,153 Prepaid and other current assets 5,175 Current assets held for sale $ 83,684 Investments in affiliated companies $ 349,308 Property, plant and equipment, net 110,591 Goodwill 77,513 Other intangible assets, net 30,713 Right-of-use lease assets 476 Other long-term assets 6,609 Long-term assets held for sale $ 575,210 LIABILITIES Accounts payable $ 10,992 Operating lease liabilities—current 214 Accrued liabilities 13,376 Current liabilities held for sale $ 24,582 Operating lease liabilities—noncurrent $ 262 Other long-term liabilities 1,906 Long-term liabilities held for sale $ 2,168 Upon the close of the transaction, the Company entered into a Transition Services Agreement with the buyer pursuant to which the buyer is receiving certain services to provide for the orderly transition of various functions and processes after the closing of the transaction. The services under the Transition Services Agreement include information technology, accounting, tax, financial services, human resources and other administrative support services. These services are being provided at cost for a period of 10 months, with the ability to extend the initial term up to two extensions, the first of which shall not exceed two months and the second shall not exceed one month. The Company did not bill any amount under the Transition Services Agreement to the buyer during the year ended December 31, 2025. F-20 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) Investments in affiliated companies The disposal group includes the Company’s investment in the Zeolyst Joint Venture, each of which are 50/50 joint ventures with CRI Zeolites Inc. (a wholly-owned subsidiary of Royal Dutch Shell). The Zeolyst Joint Venture was historically accounted for under the equity method. As of December 31, 2025, the Company’s consolidated balance sheet does not include any investments related to the Zeolyst Joint Venture. The following table provides summarized financial information of the combined investments in affiliated companies that were included within the divested business unit: December 31, 2024 Current assets $ 254,541 Noncurrent assets 166,999 Current liabilities 27,226 Noncurrent liabilities 5,649 Years ended December 31, 2025 2024 2023 Sales $ 312,629 $ 286,283 $ 345,002 Gross profit 78,535 78,043 107,865 Operating income 40,562 37,230 70,783 Net income 41,739 37,746 74,053 Related party transactions The Company entered into a joint venture agreement (the “ZI Partnership Agreement”) in 1988 with Shell Catalysts & Technologies, an affiliate of Royal Dutch Shell plc, to form Zeolyst International, a 50/50 joint venture partnership (the “Partnership”). Under the terms of the ZI Partnership Agreement, the Partnership leases certain land used in its Kansas City production facilities from Advanced Materials & Catalysts. This lease, which has been recorded as an operating lease and with evergreen terms as long as the ZI Partnership Agreement is in place, provided for rental payments to Advanced Materials & Catalysts of $ 310 during the years ended December 31, 2025, 2024 and 2023. These rental payments were included in Advanced Materials & Catalysts’ cost of goods sold within net (loss) income from discontinued operations, net of tax. The Partnership had no sales to Advanced Materials & Catalysts for the years ended December 31, 2025 and 2024, and sales of $ 236 to Advanced Materials & Catalysts for the year ended December 31, 2023. The Partnership purchases certain raw materials from Advanced Materials & Catalysts and was charged for various manufacturing costs incurred at Advanced Materials & Catalysts’ Kansas City production facility. The amount of these costs charged to the Partnership were $ 19,553 , $ 17,315 and $ 20,594 for the years ended December 31, 2025, 2024 and 2023, respectively. Of these charges, $ 4,842 , $ 2,110 and $ 2,457 were included in Advanced Materials & Catalysts’ sales within net (loss) income from discontinued operations, net of tax, and $ 14,711 , $ 15,205 and $ 18,137 were included in Advanced Materials & Catalysts’ cost of goods sold within net (loss) income from discontinued operations, net of tax for the years ended December 31, 2025, 2024 and 2023, respectively. In addition, the Partnership was charged certain product demonstration costs of $ 1,058 , $ 1,029 and $ 1,819 during the years ended December 31, 2025, 2024 and 2023, respectively, which were also included in Advanced Materials & Catalysts’ cost of goods sold within net (loss) income from discontinued operations, net of tax. Certain administrative services were provided to the affiliated company by the Company. The Company charged $ 2,304 , $ 2,749 and $ 2,134 for the years ended December 31, 2025, 2024 and 2023, respectively, which were included in selling, general and administrative expenses in the consolidated statements of (loss) income. Certain administrative, marketing, engineering, management-related and research and development services are provided to the Partnership by Advanced Materials & Catalysts. The Partnership was charged $ 14,528 , $ 14,454 and $ 12,624 for the years ended December 31, 2025, 2024 and 2023, respectively and were included in Advanced Materials F-21 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) & Catalysts’ selling, general and administrative expenses within net (loss) income from discontinued operations, net of tax. Advanced Materials & Catalysts had an accounts receivable from the Partnership of $ 2,794 as of December 31, 2024, which was included in Advanced Materials & Catalysts’ prepaid and other current assets within current assets held for sale in the consolidated balance sheets. Advanced Materials & Catalysts had no accounts payable with the Partnership as of December 31, 2024. Other Divestitures During the year ended December 31, 2025, the Company recorded an adjustment related to a historical divestiture in the amount of of $ 2,409 which is included in net (loss) income from discontinued operations, net of tax. 5. Acquisition: On May 6, 2025 (the “Closing Date”), the Company completed its acquisition of the sulfuric acid production assets of Cornerstone Chemical Company LLC (“Cornerstone”) located in Waggaman, Louisiana. As part of an asset purchase agreement (the “Acquisition”), the Company paid $ 41,480 in cash, consisting of the $ 35,000 purchase price plus $ 6,480 of adjustments for working capital, pursuant to the agreement. The sulfuric acid production assets will be used to increase capacity of virgin sulfuric acid and regenerated sulfuric acid to current and future customers. The Acquisition is a business combination, therefore the acquisition method was applied. Under the acquisition method, the purchase price was allocated to the identifiable assets acquired based on the fair values of the identifiable assets acquired as of the Closing Date. The excess of the purchase price over fair values of the identifiable assets acquired was recorded to goodwill. The following table sets forth the calculation and allocation of the purchase price to the identifiable net assets acquired with respect to the Acquisition, which was complete as of December 31, 2025: Preliminary Purchase Price Allocation Adjustments Purchase Price Allocation Cash paid $ 41,315 $ 165 $ 41,480 Recognized amounts of identifiable assets acquired: Accounts receivable $ 9,812 $ 179 $ 9,991 Inventories 3,055 204 3,259 Property, plant and equipment 25,000 — 25,000 Other intangible assets 2,390 ( 10 ) 2,380 Other long-term assets 695 — 695 Fair value of identifiable assets acquired 40,952 373 41,325 Goodwill 363 ( 208 ) 155 Total assets acquired $ 41,315 $ 165 $ 41,480 The final purchase price allocation was updated during the fourth quarter of 2025 for certain adjustments based on revised estimates of fair value as shown above. In accordance with the requirements of the purchase method of accounting for acquisitions, accounts receivable and inventories were recorded at fair market value. As of the Closing Date, the fair value of accounts receivable approximated historical cost. The gross contractual amount of accounts receivable at the Closing Date was $ 9,991 , of which there was no amount deemed uncollectible. Fair value of inventory is defined as estimated selling prices less the sum of (a) costs of disposal and (b) a reasonable profit allowance for the selling effort of the acquiring entity. F-22 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) Prior to the acquisition, the Company had a preexisting relationship with Cornerstone. The Company had a net payable for a sulfuric acid exchange balance that was settled in the amount of $ 450 . As part of the acquisition terms, the payable was settled at cost, which was recorded separate from the business combination. The valuation of intangibles assets acquired and the related weighted-average amortization period are as follows: Amount Weighted-Average Expected Useful Life (in years) Intangible assets subject to amortization: Customer relationships $ 2,380 15 The Company evaluated the disclosure requirements under ASC 805 and determined the Acquisition was not considered a material business combination for purposes of disclosing the sales and earnings attributable to Cornerstone since the date of acquisition or supplemental pro forma information. Acquisition and integration costs were $ 6,086 for the year ended December 31, 2025, and are included in other operating expense, net in the Company’s consolidated statements of (loss) income. The Company entered into an agreement with Cornerstone to lease the land where the acquired assets are located for a 7-year term plus renewal options. Additionally, Cornerstone will charge the Company for site services and utilities for the location. 6. Revenue from Contracts with Customers: Revenue Recognition Model As described in Note 2, the Company applies the five-step revenue recognition model to each contract with its customers. Evidence of a contract between the Company and its customers may take the form of a master service agreement (“MSA”), a MSA in combination with an underlying purchase order, a combination of a pricing quote with an underlying purchase order or an individual purchase order received from a customer. The Company and certain of its customers enter into MSAs that establish the terms, including prices, under which orders to purchase goods may be placed. In cases where the MSA contains a distinct order for goods or contains an enforceable minimum quantity to be purchased by the customer, the Company considers the MSA to be evidence of a contract between the Company and its customer as the MSA creates enforceable rights and obligations. In cases where the MSA does not contain a distinct order for goods, the Company’s contract with a customer is the purchase order issued under the MSA. Customers of the Company may also negotiate orders via pricing quotes, which typically detail product pricing, delivery terms and payment information. When a customer procures goods under this method, the Company considers the combination of the pricing quote and the purchase order to create enforceable rights and obligations. Absent either a MSA or pricing quote, the Company considers an individual purchase order remitted by a customer to create enforceable rights and obligations. The Company identifies a performance obligation in a contract for each promised good that is separately identifiable from other promises in the contract and for which the customer can benefit from the good. The majority of the Company’s contracts have a single performance obligation, which is the promise to transfer individual goods to the customer. Single performance obligations are satisfied according to the shipping terms noted within the MSA or purchase order. The Company has certain contracts that include multiple performance obligations under which the purchase price for each distinct performance obligation is defined in the contract. Revenue from product sales are recorded at the sales price, which includes estimates of variable consideration for which reserves are established and which result from discounts, returns or other allowances that are offered within contracts between the Company and its customers. The Company recognizes revenues when performance obligations under the terms of a contract with its customer are satisfied, which generally occurs at a point in time by transferring control of a product to the customer. The Company determines the point in time when a customer obtains control of a product and the Company satisfies the performance F-23 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) obligation by considering factors including when the Company has a right to payment for the product, the customer has legal title to the product, the Company has transferred possession of the product, the customer has assumed the risks and rewards of ownership of the product and the customer has accepted the product. Revenue is measured as the amount of consideration the Company expects to receive in exchange for transferring goods. The Company does not have any significant payment terms as payment is received at, or shortly after, the point of sale. Contracts are typically evidenced by entering into a MSA which generally has a stated contract term in excess of one year. Though each MSA is unique, the terms typically stipulate promises that the Company has determined represent one distinct performance obligation, which is to provide a specified quantity of regenerated or virgin sulfuric acid. MSAs may contain raw material pricing adjustments which are typically based on a commodity index or Ecoservices’ cost to acquire the commodity. The Company’s exposure to fluctuations in raw material prices is limited, as the majority of pass-through contract provisions reset based on fluctuations in the underlying raw material price. These raw material pass-through provisions reset on a periodic basis and prospectively adjust the raw material cost component of the goods sold to the customer. The Company accounts for the raw material costs on a prospective basis, as the price changes affect the future consideration of the sale of goods. Certain of the Company’s MSAs contain minimum purchase requirements that expire within the calendar year, creating enforceable rights and obligations during the period of the minimum purchase requirement. In cases where the MSA contains an enforceable minimum quantity to be purchased by the customer, the Company considers the MSA to be evidence of a contract between the Company and its customer as the MSA creates enforceable right and obligations. The Company reviews each contract with minimum purchase requirements to determine if the customer will meet the provisions within the current calendar year. During the year ended December 31, 2025, we recognized $ 5,482 in sales for customer contractual minimums. During the years ended December 31, 2024 and 2023, there were no material instances where the Company’s customers failed to meet their contractual obligations. Contract Assets and Liabilities A contract asset is a right to consideration in exchange for goods that the Company has transferred to a customer when that right is conditional on something other than the passage of time. A contract liability exists when the Company receives consideration in advance of the fulfillment of its performance obligations. The Company has no contract assets or material contract liabilities recorded on its consolidated balance sheets as of December 31, 2025 and 2024, respectively. Practical Expedients and Accounting Policy Elections The Company has elected to use certain practical expedients and has made certain accounting policy elections as permitted under the revenue recognition guidance. The majority of the Company’s contracts with customers are based on an individual purchase order or a MSA in combination with an individual purchase order; thus, the duration of these contracts are for one year or less. As described above, the Company’s performance obligations reset either monthly or at the end of the calendar year. The Company has made an accounting policy election to omit certain disclosures related to these performance obligations, as the initial term of the Company’s performance obligations are for a term of one year or less. When the Company performs shipping and handling activities after the transfer of control to the customer (e.g. when control transfers prior to delivery), they are considered fulfillment activities as opposed to separate performance obligations, and the Company recognizes revenue upon the transfer of control to the customer. Accordingly, the costs associated with these shipping and handling activities are accrued when the related revenue is recognized under the Company’s policy election. The Company does not utilize sales-based commissions plans, and as a result, the Company does not capitalize any costs which could be considered incremental costs of obtaining a contract. Sales, value added and other taxes the Company collects concurrent with revenue producing activities are excluded from revenues. F-24 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) Disaggregated Revenue The Company’s portfolio of products is integrated into a variety of end uses. The Company’s primary means of disaggregating revenues is by key end uses, which are described in the table below. Key End Uses Key Products Regeneration and treatment services • Regenerated sulfuric acid • Hazardous waste treatment services Industrial, mining & automotive • Virgin sulfuric acid for mining • Virgin sulfuric acid derivatives for industrial production • Virgin sulfuric acid derivatives for nylon production Other • Catalyst activation • Aluminum sulfate solution • Ammonium bisulfite solution The following table disaggregates the Company’s sales, by key end uses, for the years ended December 31, 2025, 2024 and 2023, respectively: Years ended December 31, 2025 2024 2023 Regeneration and treatment services (1) $ 361,240 $ 357,376 $ 354,606 Industrial, mining & automotive 327,935 206,923 200,389 Other 34,340 33,996 29,850 Total sales $ 723,515 $ 598,295 $ 584,845 (1) As described in Note 1 to these consolidated financial statements, the Company experiences seasonal sales fluctuations to customers in the regeneration services product group. F-25 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) 7. Fair Value Measurements: Fair values are based on quoted market prices when available. When market prices are not available, fair values are generally estimated using discounted cash flow analyses, incorporating current market inputs for similar financial instruments with comparable terms and credit quality. In instances where there is little or no market activity for the same or similar instruments, the Company estimates fair values using methods, models and assumptions that management believes a hypothetical market participant would use to determine a current transaction price. These valuation techniques involve some level of management estimation and judgment that becomes significant with increasingly complex instruments or pricing models. Where appropriate, adjustments are included to reflect the risk inherent in a particular methodology, model or input used. The Company’s financial assets and liabilities carried at fair value have been classified based upon a fair value hierarchy. The hierarchy gives the highest ranking to fair values determined using unadjusted quoted prices in active markets for identical assets and liabilities (Level 1) and the lowest ranking to fair values determined using methodologies and models with unobservable inputs (Level 3). The classification of an asset or a liability is based on the lowest level input that is significant to its measurement. For example, a Level 3 fair value measurement may include inputs that are both observable (Levels 1 and 2) and unobservable (Level 3). The levels of the fair value hierarchy are as follows: • Level 1—Values are unadjusted quoted prices for identical assets and liabilities in active markets accessible at the measurement date. Active markets provide pricing data for trades occurring at least weekly and include exchanges and dealer markets. • Level 2—Inputs include quoted prices for similar assets or liabilities in active markets, quoted prices from those willing to trade in markets that are not active, or other inputs that are observable or can be corroborated by market data for the term of the instrument. Such inputs include market interest rates and volatilities, spreads and yield curves. • Level 3—Certain inputs are unobservable (supported by little or no market activity) and significant to the fair value measurement. Unobservable inputs reflect the Company’s best estimate of what hypothetical market participants would use to determine a transaction price for the asset or liability at the reporting date. Fair value on a recurring basis The following tables present information about the Company’s assets and liabilities that were measured at fair value on a recurring basis as of December 31, 2025 and 2024, and indicates the fair value hierarchy of the valuation techniques the Company utilized to determine such fair value: December 31, 2025 Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Derivative assets: Interest rate caps (Note 17) $ 1,312 $ — $ 1,312 $ — Derivative liabilities: Interest rate caps (Note 17) $ 1,237 $ — $ 1,237 $ — December 31, 2024 Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Derivative assets: Interest rate caps (Note 17) $ 12,500 $ — $ 12,500 $ — Derivative liabilities: Interest rate caps (Note 17) $ 710 $ — $ 710 $ — F-26 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) Derivative contracts Derivative assets and liabilities can be exchange-traded or traded over-the-counter (“OTC”). The Company generally values exchange-traded derivatives using models that calibrate to market transactions and eliminate timing differences between the closing price of the exchange-traded derivatives and their underlying instruments. OTC derivatives are valued using market transactions and other market evidence whenever possible, including market-based inputs to models, model calibration to market transactions, broker or dealer quotations or alternative pricing sources with reasonable levels of price transparency. When models are used, the selection of a particular model to value an OTC derivative depends on the contractual terms of, and specific risks inherent in, the instrument as well as the availability of pricing information in the market. The Company generally uses similar models to value similar instruments. Valuation models require a variety of inputs, including contractual terms, market prices and rates, forward curves, measures of volatility, and correlations of such inputs. For OTC derivatives that trade in liquid markets, such as forward contracts, swaps and options, model inputs can generally be corroborated by observable market data by correlation or other means, and model selection does not involve significant management judgment. As of December 31, 2025, the Company had interest rate caps that were fair valued using Level 2 inputs. In addition, the Company applies a credit valuation adjustment to reflect credit risk which is calculated based on credit default swaps. To the extent that the Company’s net exposure under a specific master agreement is an asset, the Company utilizes the counterparty’s default swap rate. If the net exposure under a specific master agreement is a liability, the Company utilizes a default swap rate comparable to Ecovyst. The credit valuation adjustment is added to the discounted fair value to reflect the exit price that a market participant would be willing to receive to assume the Company’s liabilities or that a market participant would be willing to pay for the Company’s assets. 8. Stockholders' Equity: Accumulated Other Comprehensive Income (Loss) The following table presents the components of AOCI, net of tax, as of December 31, 2025 and 2024: December 31, 2025 2024 Amortization and unrealized gains on pension and postretirement plans, net of tax expense of $( 4,951 ) and $( 4,628 ) respectively $ 2,450 $ 1,467 Net changes in fair values of derivatives, net of tax expense of $( 380 ) and $( 3,504 ) respectively 821 9,902 Foreign currency translation adjustments — ( 18,776 ) AOCI, net of tax $ 3,271 $ ( 7,407 ) F-27 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) The following table presents the tax effects of each component of other comprehensive income (loss) for the years ended December 31, 2025, 2024 and 2023: Years ended December 31, 2025 2024 2023 Pre-tax amount Tax benefit/(expense) After-tax amount Pre-tax amount Tax benefit/(expense) After-tax amount Pre-tax amount Tax benefit/(expense) After-tax amount Defined benefit and other postretirement plans: Net gain $ 1,295 $ ( 312 ) $ 983 $ 1,169 $ ( 291 ) $ 878 $ 1,511 $ ( 297 ) $ 1,214 Net prior service cost — — — ( 30 ) 7 ( 23 ) ( 125 ) 31 ( 94 ) Benefit plans, net 1,295 ( 312 ) 983 1,139 ( 284 ) 855 1,386 ( 266 ) 1,120 Net loss from hedging activities ( 12,495 ) 3,414 ( 9,081 ) ( 3,525 ) 881 ( 2,644 ) ( 17,312 ) 5,186 ( 12,126 ) Foreign currency translation 18,776 — 18,776 ( 4,660 ) — ( 4,660 ) 4,056 — 4,056 Other comprehensive income (loss) $ 7,576 $ 3,102 $ 10,678 $ ( 7,046 ) $ 597 $ ( 6,449 ) $ ( 11,870 ) $ 4,920 $ ( 6,950 ) The following table presents the changes in AOCI, net of tax, by component for the years ended December 31, 2025 and 2024: Defined benefit and other postretirement plans Net loss from hedging activities Foreign currency translation Total December 31, 2023 $ 612 $ 12,546 $ ( 14,116 ) $ ( 958 ) Other comprehensive income (loss) before reclassifications 883 10,254 ( 4,660 ) 6,477 Amounts reclassified from AOCI (1) ( 28 ) ( 12,898 ) — ( 12,926 ) Net current period other comprehensive income (loss) 855 ( 2,644 ) ( 4,660 ) ( 6,449 ) December 31, 2024 1,467 9,902 ( 18,776 ) ( 7,407 ) Other comprehensive income (loss) before reclassifications 987 ( 3,115 ) 11,701 9,573 Amounts reclassified from AOCI (1) ( 4 ) ( 5,966 ) — ( 5,970 ) Disposal of Advanced Materials & Catalysts — — 7,075 7,075 Net current period other comprehensive income (loss) 983 ( 9,081 ) 18,776 10,678 December 31, 2025 $ 2,450 $ 821 $ — $ 3,271 (1) See the following table for details about these reclassifications. Amounts in parentheses indicate debits. F-28 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) The following table presents the reclassifications out of AOCI for the years ended December 31, 2025 and 2024: Details about AOCI Components Amount reclassified from AOCI (1) Affected line item where income is presented Years ended December 31, 2025 2024 Amortization of defined benefit and other postretirement items: Net loss $ 5 $ 8 Other expense (2) Net prior service cost — 30 Other expense (2) 5 38 Total before tax ( 1 ) ( 10 ) Tax benefit $ 4 $ 28 Net of tax Gains and losses on cash flow hedges: Interest rate caps $ 8,208 $ 17,197 Interest expense ( 2,242 ) ( 4,299 ) Tax benefit 5,966 12,898 Net of tax Total reclassifications for the period $ 5,970 $ 12,926 Net of tax (1) Amounts in parentheses indicate debits to profit/loss. (2) These AOCI components are components of net periodic pension and other postretirement cost. See Note 19 to these consolidated financial statements for additional details. Treasury Stock Repurchases 2022 Stock Repurchase Program On April 27, 2022, the Company’s board of directors (the “Board”) approved a stock repurchase program that authorized the Company to purchase up to $ 450,000 of the Company’s common stock over the four-year period from the date of approval (the “Stock Repurchase Program”). On October 30, 2025, the Board amended the Stock Repurchase Program to remove the limitation that all repurchases must be made within the four-year period from the date of original approval. Under the plan, the Company is permitted to repurchase shares from time to time for cash in open market transactions or in privately negotiated transactions in accordance with applicable federal securities laws, with the Company determining the timing and the amount of any repurchases based on its evaluation of market conditions, share price and other factors. During the year ended December 31, 2025, the Company repurchased 5,752,285 shares on the open market at an average price of $ 8.24 per share, for a total of $ 47,387 , excluding brokerage commissions and accrued excise tax . During the year ended December 31, 2025, t he Company accrued $ 392 of excise tax related to these repurchases, net of shares issued under the Company’s equity incentive program (see Note 18 to these consolidated financial statements). As of December 31, 2025, $ 182,207 was available for share repurchases under the program. During the year ended December 31, 2024, the Company repurchased 552,081 shares on the open market at an average price of $ 9.05 per share, for a total of $ 4,998 , excluding brokerage commissions and accrued excise tax. During the year ended December 31, 2024, the Company did not need to accrue excise tax related to these repurchases, net of shares issued under the Company’s equity incentive program. F-29 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) Tax Withholdings on Equity Award Vesting In connection with the vesting of restricted stock awards (“RSA” or “RSAs”), restricted stock units (“RSU” or “RSUs”) and performance stock units (“PSU” or “PSUs”), shares of common stock may be delivered to the Company by employees to satisfy withholding tax obligations at the instruction of the employee award holders. These transactions, when they occur, are accounted for as stock repurchases by the Company, with the shares returned to treasury stock at a cost representing the payment by the Company of the tax obligations on behalf of the employees in lieu of shares for the vesting event. There were 189,446 and 128,801 shares delivered to the Company to cover tax payments for the years ended December 31, 2025 and 2024 , respectively and the fair value of those shares withheld were $ 1,477 and $ 1,218 for the years ended December 31, 2025 and 2024 , respectively. 9. Other Operating Expense, Net: A summary of other operating expense, net is as follows: Years ended December 31, 2025 2024 2023 Amortization expense $ 8,626 $ 8,520 $ 8,520 Transaction and other related costs 3,428 423 2,924 Restructuring, integration and business optimization costs 4,746 267 449 Net loss on asset disposals 5,371 2,254 4,101 Other, net 5,014 1,396 369 Total other operating expense, net $ 27,185 $ 12,860 $ 16,363 10. Inventories, Net: Inventories, net are classified and valued as follows: December 31, 2025 2024 Finished products and work in process $ 21,781 $ 15,810 Raw materials 5,022 2,163 Total inventories, net $ 26,803 $ 17,973 11. Property, Plant and Equipment: A summary of property, plant and equipment, at cost, and related accumulated depreciation is as follows: December 31, 2025 2024 Land $ 89,988 $ 89,988 Buildings and improvements 59,557 54,424 Machinery and equipment 781,236 712,349 Construction in progress 32,368 25,349 Property, plant and equipment, gross 963,149 882,110 Less: accumulated depreciation ( 481,990 ) ( 423,426 ) Total property, plant and equipment, net $ 481,159 $ 458,684 Depreciation expense was $ 67,806 , $ 59,863 and $ 55,345 for the years ended December 31, 2025, 2024 and 2023, respectively. F-30 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) 12. Leases: Operating lease costs of $ 12,396 , $ 10,360 and $ 10,218 are included in cost of goods sold and in selling, general and administrative expenses on the consolidated statements of (loss) income for the years ended December 31, 2025, 2024 and 2023, respectively. Finance lease costs of $ 21 , $ 74 and $ 77 are included in cost of goods sold and in selling, general, and administrative expenses on the consolidated statements of (loss) income for the years ended December 31, 2025, 2024 and 2023, respectively. Lease income is not material to the results of operations for the years ended December 31, 2025, 2024 and 2023. The table below presents the operating and finance leases right-of-use assets and liabilities recognized on the consolidated balance sheets as of December 31, 2025 and 2024: December 31, Balance Sheet location 2025 2024 Assets Operating lease Right-of-use lease assets $ 37,935 $ 33,082 Finance lease Property, plant and equipment, net 986 1,116 Total leased assets $ 38,921 $ 34,198 Liabilities Current: Operating lease Operating lease liabilities—current $ 9,495 $ 9,053 Finance lease Accrued liabilities — 23 Noncurrent: Operating lease Operating lease liabilities—noncurrent 28,666 23,927 Total leased liabilities $ 38,161 $ 33,003 The Company’s weighted average remaining lease term and weighted average discount rate for operating and financing leases as of December 31, 2025 and 2024 are as follows: December 31, 2025 2024 Weighted average remaining lease term (in years): Operating leases 5.14 4.81 Finance leases 0.00 0.44 Weighted average discount rate: Operating leases 6.26 % 6.24 % Finance leases 0.00 % 4.09 % F-31 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) Maturities of lease liabilities as of December 31, 2025 are as follows: Year Operating Leases 2026 $ 11,788 2027 9,857 2028 7,401 2029 5,726 2030 4,111 Thereafter 5,912 Total lease payments 44,795 Less: Interest ( 6,634 ) Total lease liabilities (1) $ 38,161 (1) Refer to the above table regarding the Company’s right-of-use lease assets and lease liabilities for the classification of lease liabilities in the Company’s consolidated balance sheets as of December 31, 2025. The following table presents other information related to the Company’s operating and finance leases and the impact on the Company’s consolidated statements of cash flows: Years ended December 31, 2025 2024 Cash paid for amounts included in the measurement of lease liabilities: Payments on operating leases included in operating cash flows $ 12,079 $ 10,359 Interest payments under finance leases included in operating cash flows — 2 Principal payments under finance leases included in financing cash flows 23 76 Right-of-use assets obtained in exchange for new lease liabilities (non-cash): Operating leases 15,101 18,274 F-32 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) 13. Segment Information: The segment information herein excludes the results of the divested Advanced Materials & Catalysts segment, which is reflected in discontinued operations as described in Note 4, for all periods presented. Following the divestiture of the Advanced Materials & Catalysts segment, it was determined that the Company has one operating segment which represents one reportable segment under GAAP. The Company’s single reportable segment, Ecoservices, derives its revenue through the sale of virgin and regenerated sulfuric acid products and services. The Company’s chief operating decision maker (“CODM”) is its Chief Executive Officer. The Company’s CODM evaluates the segment operating results for performance assessment and resource allocation purposes based upon entity-wide sales and expense information reported in the consolidated statements of (loss) income. The primary measure of segment profit is net income from continuing operations as reported in the consolidated statements of (loss) income. Significant segment expense categories evaluated by the CODM include cost of goods sold, selling, general and administrative expenses, and the other line items reported in the consolidated statements of (loss) income. As the Company has a single reportable segment, assets are reported in the consolidated balance sheets and capital expenditures are reported in the consolidated statements of cash flows. The CODM evaluates entity-wide results to allocate resources (including employees, property and financial or capital resources) for the segment primarily in the annual budget and forecasting process. The CODM considers budget-to-actual variances on a monthly basis when making decisions about allocating capital and personnel to the segment. The CODM also uses consolidated results to evaluate the return on assets of the segment in connection with performance evaluation and to inform the compensation for certain employees. Geographic Information All long-lived assets are located in the United States. Substantially all of the Company’s revenue was generated from the United States. Sales by Customers The Company sold products to two customers having 10% or more of total net sales. Customer A accounted for 12.3 %, 14.0 % and 13.2 % of the Company’s total net sales for the years ended December 31, 2025, 2024 and 2023, respectively. Customer B accounted for less than 10% of the Company’s total net sales for the year ended December 31, 2025, 11.8 % of total net sales for the year ended December 31, 2024, and less than 10% of total net sales for the year ended December 31, 2023. F-33 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) 14. Goodwill and Other Intangible Assets: For the October 1, 2024 goodwill assessment, the Company identified two reporting units, which aligned with the Company’s operating segments at the time. As of September 10, 2025, the Advanced Materials & Catalysts segment was classified as held for sale and as of December 31, 2025, the Advanced Materials & Catalysts segment was sold. See Note 4 for additional information. The Company has identified one reporting unit and one reporting segment, Ecoservices, as of December 31, 2025. The following relates to our remaining Ecoservices reporting unit, unless otherwise stated. The carrying amount of goodwill associated with the Ecoservices segment was unchanged for the year ended December 31, 2024. The following table provides a summary of the change in the carrying amount of goodwill associated with the Ecoservices segment for the year ended December 31, 2025: Balance as of December 31, 2024 $ 326,589 Goodwill recognized (Note 5) 155 Balance as of December 31, 2025 $ 326,744 The Company completed its annual goodwill impairment test as of October 1, 2025 and 2024. For the annual assessments, the Company bypassed the option to perform the qualitative assessment and proceeded directly to performing the quantitative goodwill impairment test for its Ecoservices reporting unit. The quantitative test identifies both the potential existence of impairment and the amount of impairment loss. The Company determined the fair value of its reporting unit using both a market approach and an income, or discounted cash flow, approach. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The Company estimates reporting unit market approach fair value using publicly traded comparable company values and applies the selected market multiples to the reporting unit’s trailing twelve months Adjusted EBITDA. The Company estimates reporting unit income-based fair value using the discounted cash flow approach. This approach requires use of significant assumptions about future cash flows and based on management’s assessment of a number of factors. Such factors include reporting unit revenue growth rates from implementation of strategic plans, operating margin growth rates, the perpetual growth rate, and the weighted average cost of capital, as well as the reporting unit’s recent performance and management’s ability to execute on planned future strategic initiatives. Discount rate assumptions are based on an assessment of the risk inherent in those future cash flows. As of October 1, 2025, the fair value of the Company’s Ecoservices reporting unit exceeded its respective carrying value and therefore, no goodwill impairment exists for the year ended December 31, 2025. In addition to the annual goodwill impairment assessment, the Company also performed the annual impairment test over its other indefinite-lived intangible assets as of October 1, 2025 and 2024. The Company bypassed the option to perform the qualitative assessment and proceeded directly to performing the quantitative impairment test. The fair values of the Company’s indefinite-lived trade names were in excess of their carrying amounts as of the respective testing dates, and as such, there was no impairment of the Company’s indefinite-lived intangible assets for the years ended December 31, 2025 and 2024. F-34 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) Gross carrying amounts and accumulated amortization for intangible assets other than goodwill are as follows: December 31, 2025 December 31, 2024 Gross Carrying Amount Accumulated Amortization Net Balance Gross Carrying Amount Accumulated Amortization Net Balance Technical know-how $ 28,790 $ ( 21,620 ) $ 7,170 $ 28,790 $ ( 19,455 ) $ 9,335 Customer relationships 117,680 ( 81,212 ) 36,468 115,300 ( 72,885 ) 42,415 Non-compete agreements 700 ( 677 ) 23 700 ( 537 ) 163 Trade names 1,600 ( 773 ) 827 1,600 ( 613 ) 987 Total definite-lived intangible assets 148,770 ( 104,282 ) 44,488 146,390 ( 93,490 ) 52,900 Indefinite-lived trade names 14,800 — 14,800 14,800 — 14,800 Total intangible assets $ 163,570 $ ( 104,282 ) $ 59,288 $ 161,190 $ ( 93,490 ) $ 67,700 The Company amortizes technical know-how over periods that range from ten years to twenty years , customer relationships over periods that range from ten years to fifteen years , non-compete agreements over five years , trademarks over fifteen years , and trade names over ten years . Amortization expense related to technical know-how is included in cost of goods sold in the consolidated statements of (loss) income and was $ 2,165 for the years ended December 31, 2025, 2024 and 2023. Amortization expense related to customer relationships, non-compete agreements, and trade names is included in other operating expense, net in the consolidated statements of (loss) income and was $ 8,626 for the year ended December 31, 2025 and $ 8,520 for the years ended December 31, 2024 and 2023, respectively. Estimated future aggregate amortization expense of intangible assets is as follows: Year Amount 2026 $ 10,727 2027 10,704 2028 10,555 2029 8,367 2030 2,299 Thereafter 1,836 Total estimated future aggregate amortization expense $ 44,488 F-35 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) 15. Accrued Liabilities: The following table summarizes the components of accrued liabilities as follows: December 31, 2025 2024 Compensation and bonus $ 19,496 $ 16,624 Interest 4,880 10,181 Property tax 2,499 1,878 Environmental reserves (Note 22) 1,627 783 Income taxes 10,218 — Finance lease and financing obligation liabilities — 23 Derivative liabilities 841 235 Accrued net working capital adjustment (Note 4) 7,496 — Other 16,215 10,101 Total accrued liabilities $ 63,272 $ 39,825 16. Long-term Debt: The summary of long-term debt is as follows: December 31, 2025 2024 2025 Term Loan Facility $ 397,088 $ 870,817 ABL Facility — — Total debt 397,088 870,817 Original issue discount ( 2,886 ) ( 7,201 ) Deferred financing costs ( 1,621 ) ( 2,787 ) Total debt, net of original issue discount and deferred financing costs 392,581 860,829 Less: current portion — ( 8,730 ) Total long-term debt, excluding current portion $ 392,581 $ 852,099 Term Loan Facility On June 9, 2021, PQ Corporation (“PQ Corp”) and Ecovyst Catalyst Technologies LLC (“Ecovyst LLC” and, effective August 1, 2021, the “Borrower”), an indirect, wholly owned subsidiary of the Company, entered into an agreement for a senior secured term loan facility (the “2021 Term Loan Facility”) in an aggregate principal amount of $ 900,000 with an original issue discount of 0.25 % and interest at a floating rate of LIBOR (with a 0.50 % minimum LIBOR floor) plus 2.75 % per annum (or, depending on the Borrower’s first lien net leverage ratio, 2.50 %), with a maturity date of June 9, 2028. The 2021 Term Loan Facility required scheduled quarterly amortization payments, each equal to 0.25 % of the original principal amount of the loans under the 2021 Term Loan Facility. On February 9, 2023, the Company amended the 2021 Term Loan Facility to replace LIBOR with a Secured Overnight Financing Rate (“SOFR”) as the benchmark interest rate. Following this amendment, the 2021 Term Loan Facility bore interest at an adjusted SOFR rate (with a 0.50 % minimum floor) plus 2.75 % per annum (or, depending on the Borrower’s first lien net leverage ratio, 2.50 %). F-36 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) On June 12, 2024, the Company amended the 2021 Term Loan Facility to, among other things, (a) reduce the interest rate applicable to all outstanding SOFR term loans to term SOFR plus 2.25 % per annum from a maximum of adjusted term SOFR plus 2.75 % per annum, (b) reduce the interest rate applicable to all outstanding base rate term loans to the alternate base rate plus 1.25 % per annum from a maximum of the alternate base rate plus 1.75 % per annum and (c) extend the maturity date of all outstanding term loans to June 12, 2031. As a result of the amendment, there is no longer a credit spread adjustment of 10 basis points. On January 30, 2025, the Company amended the 2021 Term Loan Facility to, among other things, (a) reduce the interest rate applicable to all outstanding SOFR term loans to term SOFR plus 2.00 % per annum from a maximum of term SOFR plus 2.25 % per annum and (b) reduce the interest rate applicable to all outstanding base rate term loans to the alternate base rate plus 1.00 % per annum from a maximum of the alternate base rate plus 1.25 % per annum (the amended term loans, the “2025 Term Loan Facility”). The interest rate on the 2025 Term Loan Facility was 5.65 % as of December 31, 2025. The 2025 Term Loan Facility is guaranteed by Ecovyst Catalyst Technologies LLC and Ecoservices Operations Corp, as well as other material U.S. subsidiaries of the Company. The obligations under the 2025 Term Facility are secured (i) by a first-priority security interest in, among other things, a pledge of substantially all of the Borrower’s and the guarantors’ assets (other than collateral securing the ABL Facility on a first-priority basis) and (ii) by a second-priority security interest in receivables, inventory, deposit accounts and other collateral of the Borrower and the U.S. subsidiary guarantors securing the ABL Facility. The Company may at any time voluntarily prepay loans under the 2025 Term Loan Facility in whole or in part without premium or penalty. As a result of the Advanced Materials & Catalysts Sale, the Company was required to make a mandatory partial repayment of its 2025 Term Loan Facility in the amount of $ 161,500 . On December 31, 2025, utilizing proceeds from the Advanced Materials & Catalysts Sale, the Company completed this mandatory repayment and also made a voluntary prepayment of $ 303,500 on its 2025 Term Loan Facility, for a total repayment of $ 465,000 . As a result of the prepayment, the Company is no longer required to make quarterly amortization payments on the 2025 Term Loan Facility. Debt modification and extinguishment costs The Company evaluated the terms of the amendments in accordance with ASC 470-50 Debt - Modification and Extinguishment and determined that the amendments were a modification of debt. As a result of the mandatory repayment and voluntary prepayment, the Company wrote off $ 1,228 of unamortized deferred financing costs and $ 3,350 of original issue discount, which are included in debt modification and extinguishment costs in the consolidated statements of (loss) income during the year ended December 31, 2025. As a result of the January 2025 amendment, the Company recorded $ 960 of third-party financing costs, which is included in debt modification and extinguishment costs in the consolidated statements of (loss) income for the year ended December 31, 2025. No original issue discount was paid for the year ended December 31, 2025. As a result of the June 2024 amendment, the Company recorded $ 4,471 of third-party financing costs as debt modification and extinguishment costs in the consolidated statements of (loss) income for the year ended December 31, 2024 and capitalized $ 2,183 of original issued discount within long-term debt, excluding current portion on the consolidated balance sheets. In addition, as a result of the June 2024 amendment, $ 90 of previous unamortized deferred financing costs and original issue discount associated with the previously outstanding debt were written off as debt modification and extinguishment costs for the year ended December 31, 2024 ABL Facility On May 4, 2016, PQ Corp entered into a $ 200,000 senior secured asset-based revolving credit facility (the “ABL Facility”), which provided for $ 200,000 revolving credit commitments. On March 20, 2020, PQ Corp amended its existing ABL Facility to increase the aggregate amount of the revolving loan commitments available by $ 50,000 to $ 250,000 , consisting of up to $ 195,000 in U.S. commitments, up to $ 15,000 in Canadian commitments and up to $ 40,000 in European commitments. The maturity of the facility was extended to F-37 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) March 20, 2025. In addition, there was an annual commitment fee equal to 0.375 %, with a step-down to 0.25 % based on average usage of the revolving credit borrowings available Following the amendment, the borrowings under the amended ABL Facility bear interest at a rate equal to the LIBOR rate or the base rate plus a margin of between 1.25 % to 1.75 % or 0.25 % to 0.75 %, respectively. On June 9, 2021, PQ Corp and Ecovyst LLC entered into a third amendment agreement (the “ABL Amendment”), which amended its ABL Credit Agreement, dated as of May 4, 2016 (the “ABL Credit Agreement” and, as amended by the ABL Amendment, the “Amended ABL Credit Agreement”). The ABL Amendment, among other things, decreased the aggregate amount of revolving loan commitments available to the borrowers thereunder by an aggregate amount of $ 150,000 to $ 100,000 , consisting of $ 90,000 in U.S. commitments and $ 10,000 in European commitments and extended the maturity date with respect to borrowings under the Amended ABL Credit Agreement to August 2, 2026. On February 17, 2023, the Company amended the ABL Facility to replace LIBOR with SOFR as the benchmark interest rate. Following this amendment, the borrowings under the ABL Facility bears interest at a rate equal to an adjusted term SOFR, which includes a credit spread adjustment of 10 basis points or the base rate plus a margin of between 1.25 % to 1.75 % or 0.25 % to 0.75 %, respectively. The interest rate on the ABL Facility was 7.00 % as of December 31, 2025. On April 10, 2025, the Company amended its ABL credit agreement to, among other things, (a) reallocate all European revolving loan commitments thereunder as United States revolving loan commitments, (b) extend the maturity date with respect to borrowings under the ABL Credit Agreement by over three years to April 10, 2030 (subject to acceleration under certain circumstances), (c) reduce the interest rate applicable to outstanding revolving loans that bear interest at a rate equal to Term SOFR by removing the credit spread adjustment that was applied to Term SOFR in the ABL Credit Agreement in calculating adjusted Term SOFR, and (d) reduce the frequency of borrowing base reporting, field examinations and appraisals (subject to higher frequency under certain circumstances). As a result of the amendment, the Company capitalized $ 551 of deferred financing costs within long-term debt, excluding current portion in the condensed consolidated balance sheets during the year ended December 31, 2025. As of December 31, 2025, there were no revolving credit borrowings outstanding under the ABL Facility. Revolving credit borrowings are payable at the option of the Borrower throughout the term of the ABL Facility with the balance due August 2, 2026. The Company has the ability to request letters of credit under the ABL Facility. The Company had $ 3,230 of letters of credit outstanding as of December 31, 2025, which reduce available borrowings under the ABL Facility by such amounts. The obligations of the Borrower under the ABL Facility are guaranteed by the same U.S. subsidiary guarantors that guarantee the 2025 Term Loan Facility (as described above). The obligations of the borrowers and guarantors under the ABL Facility are secured (i) by a first-priority security interest in, among other things, substantially all of their receivables, inventory, deposit accounts and other collateral securing the ABL Facility on a first-priority basis and (ii) by a second-priority security interest in the property and assets of the Borrower and the U.S. subsidiary guarantors that secure the 2025 Term Loan Facility. The ABL Facility and the 2025 Term Loan Facility contain various restrictive covenants. Each limits the ability of the Borrower and its restricted subsidiaries to incur certain indebtedness or liens, merge, consolidate or liquidate, dispose of certain property, make investments or declare or pay dividends, make optional payments, modify certain debt instruments, enter into certain transactions with affiliates, enter into certain sales and leasebacks, and certain other non-financial restrictive covenants. The ABL Facility also contains one financial covenant which applies when minimum availability under the ABL Facility exceeds a certain threshold. During such time, the Company is required to maintain a fixed-charge coverage ratio of at least 1 .0 to 1.0. The Company was in compliance with all debt covenants as of December 31, 2025 and 2024, respectively. F-38 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) Fair Value of Debt The fair value of a financial instrument is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants. As of December 31, 2025 and 2024, the fair value of the Company’s term loan facility was $ 396,591 and $ 874,083 , respectively. The fair value is classified as Level 2 based upon the fair value hierarchy (see Note 7 to these consolidated financial statements for further information on fair value measurements). Aggregate Long-term Debt Maturities The aggregate long-term debt maturities are: Year Amount 2026 $ — 2027 — 2028 — 2029 — 2030 — Thereafter 397,088 Total aggregate long-term debt maturities $ 397,088 17. Financial Instruments: The Company uses interest rate related derivative instruments to manage its exposure to changes in interest rates on its variable-rate debt instruments. The Company does not speculate using derivative instruments. By using derivative financial instruments to hedge exposures to changes in interest rates, the Company exposes itself to credit risk and market risk. Credit risk is the failure of the counterparty to perform under the terms of the derivative contract. When the fair value of a derivative contract is an asset, the counterparty owes the Company, which creates credit risk for the Company. When the fair value of a derivative contract is a liability, the Company owes the counterparty and therefore, the Company is not exposed to the counterparty’s credit risk in those circumstances. The Company minimizes counterparty credit risk in derivative instruments by entering into transactions with high quality counterparties. The derivative instruments entered into by the Company do not contain credit-risk-related contingent features. Market risk is the adverse effect on the value of a derivative instrument that results from a change in interest rates. The market risk associated with the Company’s derivative instruments is managed by establishing and monitoring parameters that limit the types and degree of market risk that may be undertaken. Use of Derivative Financial Instruments to Manage Interest Rate Risk. The Company is exposed to fluctuations in interest rates on its senior secured credit facilities. Changes in interest rates will not affect the market value of such debt but will affect the Company’s interest payments over the term of the loans. Likewise, an increase in interest rates could have a material impact on the Company’s consolidated statements of cash flows. The Company hedges the interest rate fluctuations on debt obligations through interest rate cap agreements. The Company records these agreements at fair value as assets or liabilities in the consolidated balance sheets. As the derivatives are designated and qualify as cash flow hedges, the gains or losses on the interest rate cap agreements are recorded in stockholders’ equity as a component of other comprehensive income, net of tax. Reclassifications of the gains and losses on the interest rate cap agreements into earnings are recorded as part of interest expense in the consolidated statements of income as the Company makes its interest payments on the hedged portion of its senior secured credit facilities. Fair value is determined based on estimated amounts that would be received or paid to terminate the contracts at the reporting date based on quoted market prices. F-39 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) The following table provides a summary of the Company’s interest rate cap agreements: Financial instrument Number of instruments In effect as of December 31, 2025 Current notional amount of instruments in effect Annuitized premium of instruments in effect Cap rate in effect for all agreements at December 31, 2025 Interest rate caps 3 2 $ 625,000 $ 30,698 1.00 % The current notional amounts of the two interest rate cap agreements in effect at December 31, 2025 are $ 175,000 and $ 450,000 . The Company entered into a $ 175,000 interest rate cap agreement to mitigate interest rate volatility from August 2024 to July 2026 and a $ 450,000 to mitigate interest rate volatility from November 2025 to October 2026. During the year ended December 31, 2025, the Company dedesignated a portion of its interest rate caps. With the Company’s prepayments on the 2025 Term Loan Facility (see Note 16 to these consolidated financial statements for additional information), the original forecasted interest rate payments associated with the dedesignated portion of the interest rate cap agreement are no longer highly probable of occurring. As a result of the discontinuance of cash flow hedge accounting on this portion of the interest rate cap agreement, the Company immediately reclassified the remaining loss of $ 743 located in AOCI into earnings as part of interest expense in the consolidated statements of (loss) income. Any future gains and losses associated with the dedesignated portion of the interest rate cap agreement through its maturity in October 2026 will be recognized in earnings. The Company had a $ 150,000 interest rate cap agreement to mitigate interest rate volatility from August 2023 to July 2024, a $ 250,000 interest rate cap to mitigate interest rate volatility from September 2023 to October 2025, and a $ 200,000 interest rate cap agreement to mitigate interest rate volatility from November 2024 to October 2025. The Company also entered into a $ 200,000 forward starting interest rate cap agreement to mitigate interest volatility from August 2026 to July 2028. The fair values of derivative instruments held as of December 31, 2025 and 2024, respectively are shown below: December 31, Balance sheet location 2025 2024 Derivative assets: Derivatives designated as cash flow hedges: Interest rate caps Prepaid and other current assets $ 446 $ 6,532 Interest rate caps Other long-term assets — 5,968 446 12,500 Derivative not designated as hedging instrument: Interest rate caps Prepaid and other current assets 866 — Total derivative assets $ 1,312 $ 12,500 Derivative liabilities: Derivatives designated as cash flow hedges: Interest rate caps Accrued liabilities $ 841 $ 235 Interest rate caps Other long-term liabilities 396 475 Total derivative liabilities $ 1,237 $ 710 F-40 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) The following tables show the effect of the Company’s derivative instruments designated as cash flow hedges on AOCI and the consolidated statements of (loss) income for the years ended December 31, 2025, 2024 and 2023, respectively: Amount of (loss) gain recognized in other comprehensive income Years ended December 31, 2025 2024 2023 Interest rate caps $ ( 4,287 ) $ 13,672 $ 5,419 Amount of loss reclassified from AOCI Years ended December 31, 2025 2024 2023 Interest rate caps $ ( 8,208 ) $ ( 17,197 ) $ ( 22,731 ) Amount of loss reclassified into income Years ended December 31, 2025 2024 2023 Interest rate caps $ 8,208 $ 17,197 $ 22,731 The following table shows the amounts for the line items presented on the consolidated statements of (loss) income in which the effects of cash flow hedges are recorded for the years ended December 31, 2025, 2024 and 2023, respectively: Years ended December 31, Location and amount of gain (loss) recognized in income on cash flow hedging relationships 2025 2024 2023 Derivatives designated as cash flow hedges: Interest rate caps Interest (expense) income $ ( 34,203 ) $ ( 36,488 ) $ ( 31,697 ) The amount of net unrealized gains in AOCI related to the Company’s cash flow hedges that is expected to be reclassified to the consolidated statements of (loss) income over the next twelve months is $ 584 as of December 31, 2025. F-41 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) 18. Income Taxes: Income from continuing operations before income taxes is shown below: Years ended December 31, 2025 2024 2023 $ 25,786 $ 45,205 $ 56,949 The provision (benefit) for income taxes as shown in the accompanying consolidated statements of (loss) income consists of the following: Years ended December 31, 2025 2024 2023 Current: Federal $ ( 10,251 ) $ 3,287 $ 16,707 State ( 2,457 ) 1,423 2,401 ( 12,708 ) 4,710 19,108 Deferred: Federal 17,381 ( 2,973 ) ( 132 ) State 14,825 ( 2,036 ) ( 10,250 ) 32,206 ( 5,009 ) ( 10,382 ) Provision (benefit) for income taxes $ 19,498 $ ( 299 ) $ 8,726 During the year ended December 31, 2025, the Company has adopted ASU 2023-09 to enhance the income taxes disclosure regarding income taxes paid and the rate reconciliation disclosure. The Company has elected to apply the guidance in ASU 2023-09 prospectively. The income taxes paid by the Company, from both continuing and discontinued operations, are as follows: Year ended December 31, 2025 Federal $ 5,600 State 208 Foreign 5,240 Income taxes paid, net of refunds $ 11,048 Income taxes paid (net of refunds) exceeds 5 percent of total income taxes paid (net of refunds) in the following jurisdictions: Year ended December 31, 2025 State and local taxes Louisiana $ ( 557 ) Other states 765 Foreign taxes United Kingdom 4,606 Other foreign 634 F-42 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) Cash payments for income taxes, net of refunds, which includes activity from both continuing and discontinued operations, prior to the adoption of the guidance in ASU 2023-09 is as follows: Years ended December 31, 2024 2023 Domestic $ 22,860 $ 21,973 Foreign 3,399 464 Cash payments for income taxes, net of refunds $ 26,259 $ 22,437 The differences between income taxes expected at the U.S. federal statutory income tax rate and income taxes reported were as follows: Year ended December 31, 2025 Income from continuing operations before income taxes $ 25,786 U.S. federal statutory tax rate 5,415 21.0 % State and local income taxes, net of federal income tax effect (1) 12,884 50.0 % Nontaxable or nondeductible items Sec. 162(m) compensation disallowance 278 1.1 % Stock compensation 819 3.2 % Other 218 0.8 % Changes in unrecognized tax benefits ( 116 ) ( 0.4 ) % Provision for income taxes $ 19,498 75.6 % (1) Kansas makes up the majority (greater than 50%) of the state income tax expense (benefit), net of federal income tax effect category. Additionally, this line item includes tax expense of $ 13,305 related to the establishment of a valuation allowance on the Company’s Kansas Investment Tax Credits (“ITCs”). After the Advanced Materials & Catalysts divestiture, the Company determined that it is no longer more likely than not that these credits will be realized as it no longer owns the Kansas property which previously qualified for the respective ITCs. A reconciliation of income tax expense at the U.S. federal statutory income tax rate to actual income tax (benefit) expense prior to the adoption of the guidance in ASU 2023-09 is as follows: Years ended December 31, 2024 2023 Tax at statutory rate $ 9,493 $ 11,959 State income taxes, net of federal income tax benefit ( 919 ) 1,859 Changes in uncertain tax positions ( 9,413 ) 985 State credit - valuation allowance release — ( 10,203 ) Stock compensation 222 1,624 Compensation disallowance under 162(m) 148 2,088 Other, net 170 414 (Benefit) provision for income taxes $ ( 299 ) $ 8,726 F-43 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) Deferred tax assets (liabilities) are comprised of the following: December 31, 2025 2024 Deferred tax assets: Net operating loss carryforwards $ 13,300 $ 13,667 Interest disallowance carryforward — 2,968 Pension — 280 Inventory 1,389 — Operating lease liability 10,424 8,163 Other 10,811 17,795 State credits 13,305 14,359 Total deferred tax assets, gross 49,229 57,232 Valuation allowance ( 20,790 ) ( 7,588 ) Total deferred tax assets, net 28,439 49,644 Deferred tax liabilities: Depreciation $ ( 69,470 ) $ ( 67,888 ) Pension ( 57 ) — Inventory — ( 3,306 ) Intangibles ( 58,478 ) ( 70,677 ) Operating lease right-of-use assets ( 10,363 ) ( 8,189 ) Other ( 3,359 ) ( 4,979 ) Total deferred tax liabilities ( 141,727 ) ( 155,039 ) Net deferred tax liabilities $ ( 113,288 ) $ ( 105,395 ) Under the tax laws of various jurisdictions in which we operate, deductions or credits that cannot be fully utilized for tax purposes during the year may be carried forward, subject to statutory limitations, to reduce taxable income or taxes payable in a future year. As of December 31, 2025, the Company has $ 13,305 of deferred tax assets related to state tax credits, which are subject to a 16-year carryforward period. The Company has recorded a full valuation allowance against the state tax credits as it is more likely than not that the benefit from these state tax credits will not be realized. The Company has $ 13,300 of deferred tax assets related to state net operating losses, which are subject to various carryforward periods of 5 to 20 years. A partial valuation allowance of $ 7,485 has been recorded due to the expected expiration of these state net operating losses before they are able to be utilized. The change in net deferred tax liabilities for the years ended December 31, 2025 and 2024 was primarily driven by the Advanced Materials & Catalysts sale and reversal of the related deferred balances, differences between book and tax basis depreciation, activity with respect to tax deductible goodwill, activity with respect to interest rate caps recorded against other comprehensive income, activity with respect to the interest disallowance carryforward and activity with respect to the amortization of previously capitalized research and experimentation costs. The net change in the total valuation allowance was an increase of $ 13,202 in 2025. The valuation allowance at December 31, 2025 was related to state net operating loss carryforwards and state tax credits that, in the judgment of management, are not more likely than not to be realized. In assessing the ability to realize deferred tax assets, management considered whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Management considered the scheduled reversal of F-44 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) deferred tax liabilities (including the impact of available carryback and carryforward periods), projected future taxable income, and tax-planning strategies that are prudent in making this assessment. In order to fully realize deferred tax assets, the Company will need to generate future taxable income prior to the expiration of the net operating loss and credit carryforwards. The amount of the deferred tax assets considered realizable, however, could be reduced in the near term if estimates of future taxable income during the carryforward period are reduced. The following table summarizes the activity related to the Company’s gross unrecognized tax benefits. The amounts listed in the below table also represents the total unrecognized tax benefits that, if recognized, would impact the effective tax rate as of December 31, 2025 and 2024, respectively: Years ended December 31, 2025 2024 Balance at beginning of period $ 87 $ 8,110 Uncertain tax benefit sustained due to lapsing of statue of limitations ( 87 ) ( 8,023 ) Balance at end of period $ — $ 87 To the extent interest and penalties are not assessed with respect to uncertain tax positions, amounts accrued will be reduced and reflected as a reduction of the overall income tax provision in the period for which the event occurs requiring the adjustment. There were no interest and penalties recognized in provision (benefit) for income taxes on continuing operations for the year ended December 31, 2025. The total amount of interest and penalties recognized in provision (benefit) for income taxes on continuing operations was $ 1,390 for the year ended December 31, 2024. There were no accrued interest and penalties as of December 31, 2025. The Company files numerous consolidated and separate income tax returns in the U.S. federal jurisdiction. The following describes the open tax years, by significant tax jurisdiction, as of December 31, 2025: Jurisdiction Period United States-Federal 2022-2025 United States-State 2020-2025 Given that the Company has utilized state net operating losses in the current and prior years, the statute for examination by the state taxing authorities will typically remain open for a period following the use of such net operating loss carryforwards, extending the period for examination beyond the years indicated above. 19. Benefit Plans: The Company sponsors two funded defined benefit pension plans that cover certain employees. Benefits for the plans are generally based on average final pay and years of service. The Company’s funding policy is to fund the minimum required contributions consistent with statutory requirements based on actuarial computations utilizing the projected unit credit method of calculation. The Company sponsors an unfunded plan to provide health care benefits to certain retired employees. The plan pays a stated percentage of medical expenses reduced by deductibles and other coverage and obligations are paid out of the Company’s operations. The Company uses a December 31 measurement date for all of its defined benefit pension and postretirement medical plans. The Company has two defined benefit pension plans: the Eco Services Hourly Pension Plan which was frozen to future accruals as of December 31, 2020 and the Eco Services Pension Equity Plan which was frozen to future accruals as of December 31, 2016. The retiree healthcare plan was closed to new retirees effective July 1, 2017. F-45 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) The following tables summarize changes in the benefit obligation, plan assets and funded status of the Company’s defined benefit pension plans and other postretirement benefit plan: Defined Benefit Pension Plans Other Postretirement Benefit Plan December 31, December 31, 2025 2024 2025 2024 Change in benefit obligation: Benefit obligation at beginning of period $ 61,721 $ 66,556 $ 463 $ 475 Interest cost 3,278 3,227 26 24 Plan settlements ( 1,013 ) ( 1,348 ) — — Benefits paid ( 3,464 ) ( 3,254 ) — — Premiums paid — — ( 3 ) ( 3 ) Actuarial loss (gain) 1,529 ( 3,460 ) 2 ( 33 ) Benefit obligation at end of the period 62,051 61,721 488 463 Change in plan assets: Fair value of plan assets at beginning of period $ 59,689 $ 61,618 $ — $ — Actual return on plan assets 6,066 1,048 — — Employer contributions 480 1,625 3 3 Plan settlements ( 1,013 ) ( 1,348 ) — — Benefits paid ( 3,464 ) ( 3,254 ) — — Premiums paid — — ( 3 ) ( 3 ) Fair value of plan assets at end of the period 61,758 59,689 — — Funded status of the plans (underfunded) $ ( 293 ) $ ( 2,032 ) $ ( 488 ) $ ( 463 ) Defined Benefit Pension Plans — The actuarial loss for the year ended December 31, 2025 was $ 1,529 , which was driven by decreases in the discount rates of $ 1,429 and declines in general demographic experience of $ 100 . The actuarial gain for the year ended December 31, 2024 was $ 3,460 , which was driven by increases in the discount rates of $ 2,760 and improvements in general demographic experience of $ 700 . Amounts recognized in the consolidated balance sheets consist of: Defined Benefit Pension Plans Other Postretirement Benefit Plan December 31, December 31, 2025 2024 2025 2024 Noncurrent asset $ 1,043 $ 90 $ — $ — Current liability — — ( 22 ) ( 20 ) Noncurrent liability ( 1,337 ) ( 2,122 ) ( 466 ) ( 443 ) AOCI, net of tax 2,374 1,386 76 81 Net amount recognized $ 2,080 $ ( 646 ) $ ( 412 ) $ ( 382 ) The net amount of projected benefit obligation and plan assets for all underfunded plans was classified as noncurrent liabilities in the consolidated balance sheets. F-46 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) Amounts recognized in AOCI consist of: Defined Benefit Pension Plans Other Postretirement Benefit Plan December 31, December 31, 2025 2024 2025 2024 Net gain $ 3,143 $ 1,849 $ 101 $ 107 Gross amount recognized 3,143 1,849 101 107 Deferred income taxes ( 769 ) ( 463 ) ( 25 ) ( 26 ) Net amount recognized $ 2,374 $ 1,386 $ 76 $ 81 Components of net periodic (benefit) expense consist of: Defined Benefit Pension Plans Other Postretirement Benefit Plan Years ended December 31, Years ended December 31, 2025 2024 2023 2025 2024 2023 Interest cost $ 3,278 $ 3,227 $ 3,453 $ 26 $ 24 $ 24 Expected return on plan assets ( 3,234 ) ( 3,367 ) ( 3,305 ) — — — Amortization of prior service credit — — — — ( 30 ) ( 125 ) Amortization of net (gain) loss — — — ( 4 ) ( 2 ) ( 2 ) Settlement (gain) loss ( 1 ) ( 6 ) 61 — — — Net periodic (benefit) expense $ 43 $ ( 146 ) $ 209 $ 22 $ ( 8 ) $ ( 103 ) All components of net periodic (benefit) expense are presented within other (income) expense, net in the Company’s consolidated statements of (loss) income. F-47 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) Components of other changes in plan assets and benefit obligations recognized in other comprehensive income consists of: Defined Benefit Pension Plans Other Postretirement Benefit Plan December 31, December 31, 2025 2024 2025 2024 Net (gain) loss $ ( 1,297 ) $ ( 1,136 ) $ 2 $ ( 33 ) Amortization of prior service credit — — — 30 Amortization or settlement recognition of net gain 1 6 4 2 Total recognized in other comprehensive (income) loss ( 1,296 ) ( 1,130 ) 6 ( 1 ) Total recognized in net periodic benefit cost and other comprehensive (income) loss $ ( 1,258 ) $ ( 1,280 ) $ 28 $ ( 9 ) The following table presents selected information about the Company’s pension plans with projected benefit obligations and accumulated benefit obligations in excess of plan assets: Defined Benefit Pension Plans Other Postretirement Benefit Plan December 31, December 31, 2025 2024 2025 2024 Projected benefit obligation $ 17,791 $ 18,305 $ 488 $ 463 Accumulated benefit obligation 17,791 18,305 — — Fair value of plan assets 16,454 16,183 — — Significant weighted average assumptions used in determining the pension obligations include the following: Defined Benefit Pension Plans Other Postretirement Benefit Plan December 31, December 31, 2025 2024 2025 2024 Discount rate 5.40 % 5.67 % 5.50 % 5.70 % Rate of compensation increase N/A N/A N/A N/A The discount rate for net periodic benefit costs is determined by utilizing a yield curve model. The model develops a spot rate curve based on the yields available from a broad-based universe of high quality corporate bonds. The discount rate is then set as the weighted average spot rate, using the respective plan’s expected benefit cash flows as the weights. Significant weighted average assumptions used in determining net periodic benefit cost include the following: Defined Benefit Pension Plans Other Postretirement Benefit Plan Years ended December 31, Years ended December 31, 2025 2024 2023 2025 2024 2023 Discount rate 5.47 % 5.23 % 5.39 % 5.70 % 5.20 % 5.50 % Expected return on assets 5.69 % 5.76 % 5.74 % — % — % — % Rate of compensation increase N/A N/A N/A N/A N/A N/A F-48 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) Fair value of plan assets The investment objective for the plans is to generate returns sufficient to meet future obligations. The strategy to meet the objective includes generating attractive returns using higher returning assets such as equity securities and balancing risk using less volatile assets such as fixed income securities. The plans invest in an allocation of assets across the two broadly-defined financial asset categories of equity and fixed income securities. The target allocations for the plan assets across the two U.S. plans are as follows: 30 % equity securities and 70 % fixed income investments for the Eco Services Pension Equity Plan; and 20 % equity securities and 80 % fixed income investments for the Eco Services Hourly Pension Plan. The Company classifies plan assets based upon a fair value hierarchy where each asset within the hierarchy is based on the lowest level input that is significant to its measurement. The fair value hierarchy consists of three levels as follows: • Level 1—Values are unadjusted quoted prices for identical assets and liabilities in active markets accessible at the measurement date. Active markets provide pricing data for trades occurring at least weekly and include exchanges and dealer markets. Level 1 assets primarily include investments in publicly traded equity securities and mutual funds. These securities (or the underlying investments of the funds) are actively traded and valued using quoted prices for identical securities from the market exchanges. • Level 2—Inputs include quoted prices for similar assets or liabilities in active markets, quoted prices from those willing to trade in markets that are not active, or other inputs that are observable or can be corroborated by market data for the term of the instrument. Such inputs include market interest rates and volatilities, spreads and yield curves. Level 2 assets primarily consist of fixed-income securities and commingled funds that are not actively traded or whose underlying investments are valued using observable marketplace inputs. The fair value of plan assets invested in fixed-income securities is generally determined using valuation models that use observable inputs such as interest rates, bond yields, low-volume market quotes and quoted prices for similar assets. Plan assets that are invested in commingled funds are valued using a unit price or net asset value (“NAV”) that is based on the underlying investments of the fund. • Level 3—Certain inputs are unobservable (supported by little or no market activity) and significant to the fair value measurement. Unobservable inputs reflect the Company’s best estimate of what hypothetical market participants would use to determine a transaction price for the asset or liability at the reporting date. Level 3 assets include investments covered by insurance contracts and real estate funds valued using significant unobservable inputs. F-49 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) The following tables set forth by level, within the fair value hierarchy, plan assets at fair value: December 31, 2025 Total Level 1 Level 2 Level 3 Cash and cash equivalents $ 298 $ 298 $ — $ — Equity securities: Domestic stocks 8,430 8,430 — — International stocks 5,558 5,558 — — Fixed income securities: Treasury funds 12,209 12,209 — — Corporate and other bonds 35,263 35,263 — — Total $ 61,758 $ 61,758 $ — $ — December 31, 2024 Total Level 1 Level 2 Level 3 Cash and cash equivalents $ — $ — $ — $ — Equity securities: Domestic stocks 8,248 8,248 — — International stocks 5,335 5,335 — — Fixed income securities: Treasury funds 11,853 11,853 — — Corporate and other bonds 34,253 34,253 — — Total $ 59,689 $ 59,689 $ — $ — The following benefit payments, which reflect expected future service as appropriate, are expected to be paid: Year Defined Benefit Pension Plans Other Postretirement Benefit Plan 2026 $ 7,186 $ 22 2027 4,671 24 2028 4,813 25 2029 4,660 27 2030 5,149 29 2031-2035 21,801 177 The Company expects to contribute $ 680 to its defined benefit pension plans and $ 22 to the other postretirement benefit plan in 2026. There are no Medicare subsidy receipts expected in future periods. Defined Contribution Plans The Company has defined contribution plans covering domestic employees of the Company. Prior to the closing of the Advanced Materials & Catalysts sale, the defined contribution plans also covered a foreign subsidiary. The Company recorded expenses, including expenses related to discontinued operations, of $ 8,528 , $ 7,619 and $ 7,015 related to these plans for the years ended December 31, 2025, 2024 and 2023, respectively. F-50 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) 20. Stock-Based Compensation: The Company has an equity incentive plan under which it grants common stock awards to employees, directors and affiliates of the Company. At December 31, 2025, 7,405,254 shares of common stock were available for issuance under the plan. Beginning on July 1, 2023, the Company settles these awards through the issuance of treasury shares under its equity incentive plan. The Company has granted RSAs, RSUs and PSUs as part of its equity incentive compensation program. Modifications Sale of Advanced Materials & Catalysts The Compensation Committee of the Company’s Board (“Compensation Committee”) approved modifications with respect to RSUs held by employees of the Advanced Materials & Catalysts business at the time of the sale (see Note 4 to these consolidated financial statements). These modifications provide that any unvested RSUs held by Advanced Materials & Catalysts employees which are due to vest by April 30, 2026, will continue to follow their initial vesting schedule, as long as the employee stays employed by the Buyer until the vesting date. Any unvested RSUs that were scheduled to vest after April 30, 2026, were forfeited at the time of the sale in accordance with the original RSU terms. This modification did not have a material impact on stock-based compensation expense. Stock Options The Company has issued stock options to purchase Ecovyst Inc. common stock as part of its equity incentive compensation program. There are various vesting conditions associated with stock options issued prior to the launch of the Company’s initial public offering (“IPO”) in September 2017, including satisfaction of certain service and/or performance based conditions. Subsequent to the IPO, the Company’s stock option grants have been subject to graded vesting conditions based on service. The maximum contractual term of the Company’s stock options is ten years . The following table summarizes the activity of common stock options for the period from December 31, 2022 through the year ended December 31, 2025: Number of Options Weighted Average Exercise Price Weighted Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2022 1,520,997 $ 7.24 Exercised ( 197,941 ) $ 2.58 Forfeited ( 284,956 ) $ 3.39 Expired ( 328,677 ) $ 12.36 Outstanding at December 31, 2023 709,423 $ 7.73 Exercised ( 93,962 ) $ 3.04 Outstanding at December 31, 2024 615,461 $ 8.44 Exercised ( 158,574 ) $ 3.05 Outstanding at December 31, 2025 456,887 $ 10.31 1.55 $ 574 Exercisable at December 31, 2025 456,887 $ 10.31 1.55 $ 574 The aggregate intrinsic value per the above table represents the difference between the fair value the Company’s common stock on the last trading day of the reporting period (determined in accordance with the plan terms) and the exercise price of in-the-money stock options multiplied by the respective number of stock options as of that date. The total intrinsic value of stock options exercised were $ 896 , $ 472 and $ 1,693 during the years ended December 31, 2025, 2024 and 2023 respectively. Additionally, cash proceeds received by the Company from the exercise of stock options were no t material for the years ended December 31, 2025, 2024 and 2023 respectively. F-51 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) There were no stock option awards granted during the years ended December 31, 2025, 2024 and 2023. The Company uses the Black-Scholes option pricing model to determine the fair value of its stock option grants. Restricted Stock Awards, Restricted Stock Units and Performance Stock Units RSA The Company has granted RSAs subject to vesting conditions based on (1) service only, (2) performance only or (3) a combination of service and performance conditions, dependent on which event occurs first. The vesting requirements for the majority of these awards were based upon the achievement of a performance condition. As defined in the award agreements, each award subject to the performance condition fully vests upon the occurrence of a defined liquidity event upon which certain investment funds affiliated with CCMP, a former stockholder, receive proceeds exceeding certain thresholds. Although achievement of the performance condition is subject to continued service with the Company, the terms of awards issued with performance conditions stipulate that the performance vesting condition can be attained for a period of six months following separation from service under certain circumstances, depending on the means of separation from the Company and subject to other factors such as individual separation agreements. The same performance vesting condition for the Company’s RSAs also governs the achievement of the performance vesting condition for the Company’s stock options. During the year ended December 31, 2025, the Company did not grant any RSAs. As of December 31, 2025, the Company did not have any outstanding unvested RSAs subject to performance vesting condition. RSU During the year ended December 31, 2025, the Company granted 985,551 RSUs under its equity incentive plan. Each RSU provides the recipient with the right to receive a share of common stock subject to graded vesting terms based on service, which for the awards granted during the year ended December 31, 2025, generally requires approximately one year of service for members of the Company’s board of directors and approximately three years of service for employees. The value of the RSUs granted during the year ended December 31, 2025 was based on the average of the high and low trading prices of the Company’s common stock on the NYSE on the preceding trading day, in accordance with the Company’s policy for valuing such awards. Compensation expense related to the RSUs is recognized on a straight-line basis over the respective vesting period. PSU 2025 Grants During the year ended December 31, 2025, the Company granted 508,109 PSUs (at target) under its equity incentive plan. The PSUs granted during the year ended December 31, 2025 provide the recipients with the right to receive shares of common stock dependent on 50 % of a Company-specific financial performance target and 50 % on the relative increase in the total shareholder return (“TSR”) goal (“the Performance measures”). The Performance measures are measured independently of each other, but achievement of both metrics is measured on the same three-year performance period from January 1, 2025 through December 31, 2027 (“Performance period”). Depending on the Company’s performance relative to the Performance measures, each PSU award recipient is eligible to receive a percentage of the target number of shares granted to the recipient, ranging from zero to 200 %. The PSUs, to the extent earned, will vest on the date the Compensation Committee certifies the achievement of the Performance measures for the Performance period, which will occur subsequent to the end of the Performance period and after the Company files its annual consolidated financial statements for the year ending December 31, 2027. F-52 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) Achievement of the Company-specific financial performance target is measured based on the actual three-year cumulative results across the Performance period. The TSR goal is based on the Company’s actual TSR performance against companies in the S&P 1500 Specialty Chemicals Index over the Performance period. The TSR goal, which determines how much of the 50 % of the PSUs granted during 2025 may be earned, is considered a market condition as opposed to a vesting condition. Because a market condition is not considered a vesting condition, it is reflected in the grant date fair value of the award and the associated compensation cost based on the fair value of the award is recognized over the Performance period, regardless of whether the Company actually achieves the market condition or the level of achievement, as long as service is provided by the recipient. 2024 Grants During the year ended December 31, 2024, the Company granted 535,629 PSUs (at target) under its equity incentive plan. The PSUs granted during the year ended December 31, 2025 provide the recipients with the right to receive shares of common stock dependent on 50 % of a Company-specific financial performance target and 50 % on the relative increase in the total shareholder return (“TSR”) goal (“the Performance measures”). The Performance measures are measured independently of each other, but achievement of both metrics is measured on the same three-year performance period from January 1, 2024 through December 31, 2026 (“Performance period”). Depending on the Company’s performance relative to the Performance measures, each PSU award recipient is eligible to receive a percentage of the target number of shares granted to the recipient, ranging from zero to 200 %. The PSUs, to the extent earned, will vest on the date the Compensation Committee of the Company’s Board of Directors (“Compensation Committee”) certifies the achievement of the Performance measures for the Performance period, which will occur subsequent to the end of the Performance period and after the Company files its annual consolidated financial statements for the year ending December 31, 2026. Achievement of the Company-specific financial performance target is measured based on the actual three-year cumulative results across the Performance period. The TSR goal is based on the Company’s actual TSR performance against companies in the S&P 1500 Specialty Chemicals Index over the Performance period. The TSR goal, which determines how much of the 50 % of the PSUs granted during 2024 may be earned, is considered a market condition as opposed to a vesting condition. Because a market condition is not considered a vesting condition, it is reflected in the grant date fair value of the award and the associated compensation cost based on the fair value of the award is recognized over the Performance period, regardless of whether the Company actually achieves the market condition or the level of achievement, as long as service is provided by the recipient. 2023 Grants During the year ended December 31, 2023, the Company granted 721,537 PSUs (at target) under its equity incentive plan. The PSUs granted during the year ended December 31, 2023 provide the recipients with the right to receive shares of common stock dependent on the achievement of a TSR goal, and are generally subject to the provision of service through the vesting date of the award. The performance period for the TSR goal is measured based on a three-year performance period from January 1, 2023 through December 31, 2025. The TSR goal is based on the Company’s actual TSR percentage increase over the performance period. Depending on the Company’s performance relative to the TSR goal, each PSU award recipient is eligible to receive a percentage of the target number of shares granted to the recipient, ranging from zero to 200 %. The PSUs, to the extent earned, will vest on the date the Compensation Committee certifies the achievement of the performance metric for the three-year period ending December 31, 2025, which will occur subsequent to the end of the performance period and after the Company files its annual consolidated financial statements for the year ending December 31, 2025. F-53 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) 2022 Grants In February 2025, the Compensation Committee certified the achievement of the performance metrics for the three-year period ended December 31, 2024, related to the PSUs granted during the year ended December 31, 2022. The PSUs granted during the year ended December 31, 2022 provide the recipients with the right to receive shares of common stock dependent on the achievement of a TSR goal and are generally subject to the provision of service through the vesting date of the award. The TSR goal was based on the Company’s actual TSR percentage increase over the performance period. The awards vested during the year ended December 31, 2025 with no percentage of the TSR goal earned. Weighted Average Assumptions The following table shows the weighted average assumptions for each of the unvested grants: 2025 Grants 2024 Grants 2023 Grants Weighted average fair value based on Monte Carlo simulation $ 10.80 (1) $ 11.64 (1) $ 12.27 Expected dividend yield — % — % — % Risk-free interest rate 4.19 % 4.09 % 3.80 % Expected volatility 40.39 % 39.45 % 48.82 % Expected term (in years) 2.90 2.95 2.96 (1) Relative to the TSR performance measure only. Award Activity The following table summarizes the activity of restricted stock awards, restricted stock units and performance stock units for the period from December 31, 2022 through the year ended December 31, 2025: Restricted Stock Awards Restricted Stock Units Performance Stock Units Number of Shares Weighted Average Grant Date Fair Value (per share) Number of Units Weighted Average Grant Date Fair Value (per share) Number of Units Weighted Average Grant Date Fair Value (per share) Nonvested as of December 31, 2022 277,056 $ 15.66 2,464,718 $ 11.73 639,532 (1) $ 16.32 Granted 5,081 $ 9.84 1,195,835 $ 9.84 721,537 $ 12.28 Vested ( 5,081 ) $ 9.84 ( 1,436,301 ) $ 11.84 ( 200,204 ) $ 20.16 Forfeited ( 277,056 ) $ 15.66 ( 261,424 ) $ 11.27 ( 201,648 ) $ 18.57 Nonvested as of December 31, 2023 — $ — 1,962,828 $ 10.55 959,217 (1) $ 11.84 Granted 4,540 $ 8.81 1,126,166 $ 8.84 535,629 $ 10.23 Vested ( 4,540 ) $ 8.81 ( 1,000,288 ) $ 11.10 — $ — Forfeited — $ — ( 111,333 ) $ 9.27 ( 141,437 ) $ 12.82 Nonvested as of December 31, 2024 — $ — 1,977,373 $ 9.37 1,353,409 (1) $ 11.10 Granted — $ — 985,551 $ 7.76 508,109 $ 9.28 Vested — $ — ( 1,053,456 ) $ 9.53 — $ — Forfeited — $ — ( 445,337 ) $ 8.46 ( 370,004 ) $ 9.56 Nonvested as of December 31, 2025 — $ — 1,464,131 $ 8.45 1,491,514 (1) $ 10.86 (1) Based on target. F-54 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) Cash proceeds received by the Company from the exercise of stock options were not material for the year ended December 31, 2025. The total fair value of RSAs that vested during the years ended December 31, 2025, 2024 and 2023 was $ 0 , $ 40 and $ 50 , respectively. The total fair value of RSUs that vested during the years ended December 31, 2025, 2024 and 2023 was $ 10,040 , $ 11,102 and $ 17,008 , respectively. The total fair value of PSUs that vested during the years ended December 31, 2025, 2024 and 2023 was $ 0 , $ 0 and $ 4,035 , respectively. Prior to the Company’s IPO, the Company issued restricted stock awards and stock options with performance conditions that were based on the occurrence of a defined liquidity event upon which certain investment funds affiliated with CCMP receive proceeds exceeding defined thresholds. In addition to the defined liquidity event, subsequent to the Company’s IPO, the performance vesting condition can also be achieved if the average closing trading price of the Company’s common stock on the NYSE over any consecutive ten-day trading period equals or exceeds a price that would be equivalent to the achievement of the threshold proceeds to CCMP. When a liquidity event occurred on March 7, 2023, the investment funds affiliated with CCMP received proceeds that did not exceed the defined thresholds. As a result, all of the Company’s RSAs and stock options subject to the performance condition were forfeited and cancelled. See Note 21 to these consolidated financial statements for further information on the number of RSAs and stock options outstanding subject to performance-based vesting. Stock-Based Compensation Expense For the years ended December 31, 2025, 2024 and 2023, total stock-based compensation expense for the Company included in continuing operations was $ 9,746 , $ 11,126 and $ 12,984 , respectively. The associated income tax benefit recognized in the consolidated statements of income for the years ended December 31, 2025, 2024 and 2023 was $ 1,597 , $ 2,493 and $ 1,655 , respectively. As of December 31, 2025, there was no unrecognized compensation cost related to nonvested RSAs subject to service vesting conditions. As of December 31, 2025, unrecognized compensation cost was $ 4,567 for RSUs and $ 3,786 for PSUs. The weighted-average period over which these costs are expected to be recognized at December 31, 2025 is 1.64 years for the RSUs and 1.79 years for the PSUs. No expense has been recognized for any stock options subject to the performance condition for the years ended December 31, 2025, 2024 and 2023, and no expense has been recognized for any RSAs subject to the performance condition for the years ended December 31, 2025 and 2024, as the performance-based criteria was not achieved nor considered probable of achievement. 21. Earnings per Share: Basic earnings per share is calculated as income available to common stockholders, divided by the weighted average number of common shares outstanding during the period. The weighted average number of common shares outstanding during the period for the computation of basic earnings per share excludes RSAs that have legally been issued but are nonvested during the period, as the sale of these shares is prohibited pending satisfaction of certain vesting conditions by the award recipients in order to earn the rights to the shares (see Note 20 to these consolidated financial statements for further information regarding outstanding nonvested restricted stock awards). Diluted earnings per share is calculated as income available to common stockholders, divided by the weighted average number of common and potential common shares outstanding during the period, if dilutive. Potential common shares reflect (1) unvested RSAs and RSUs with service vesting conditions, (2) PSUs with vesting conditions considered probable of achievement and (3) options to purchase common stock, all of which have been included in the diluted earnings per share calculation using the treasury stock method. F-55 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) The reconciliation from basic to diluted weighted average shares outstanding is as follows: Years ended December 31, 2025 2024 2023 Weighted average shares outstanding – Basic 115,291,879 116,719,437 118,367,214 Dilutive effect of unvested common shares and RSUs with service conditions, PSUs considered probable of vesting and assumed stock option exercises and conversions 665,683 728,001 1,120,495 Weighted average shares outstanding – Diluted 115,957,562 117,447,438 119,487,709 The Company utilizes the control number concept in the computation of diluted earnings per share to determine whether potential common stock equivalents are dilutive. The control number used is income from continuing operations. The control number concept requires that the same number of potentially dilutive securities applied in computing diluted earnings per share from continuing operations be applied to all other categories of income or loss, regardless of their anti-dilutive effect on such categories. Basic and diluted income per share are calculated as follows: Years ended December 31, 2025 2024 2023 Numerator: Net income from continuing operations $ 6,288 $ 45,504 $ 48,223 Net (loss) income from discontinued operations, net of tax ( 77,414 ) ( 52,156 ) 22,931 Net (loss) income $ ( 71,126 ) $ ( 6,652 ) $ 71,154 Denominator: Weighted average shares outstanding – Basic 115,291,879 116,719,437 118,367,214 Weighted average shares outstanding – Diluted 115,957,562 117,447,438 119,487,709 Net (loss) income per share: Basic income per share—continuing operations $ 0.05 $ 0.39 $ 0.41 Diluted income per share—continuing operations $ 0.05 $ 0.39 $ 0.40 Basic (loss) income per share—discontinued operations $ ( 0.67 ) $ ( 0.45 ) $ 0.19 Diluted (loss) income per share—discontinued operations $ ( 0.67 ) $ ( 0.44 ) $ 0.19 Basic (loss) income per share $ ( 0.62 ) $ ( 0.06 ) $ 0.60 Diluted (loss) income per share $ ( 0.61 ) $ ( 0.06 ) $ 0.60 F-56 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) The table below presents additional details of the Company’s weighted average equity-based awards outstanding during each respective year that were excluded from the calculation of diluted earnings per share: Years ended December 31, 2025 2024 2023 Stock options with performance only targets not yet achieved — — 51,526 Anti-dilutive RSUs and PSUs 282,675 387,078 286,729 Anti-dilutive stock options 367,100 367,100 508,623 RSAs and stock options with performance only vesting conditions were not included in the dilution calculation, as the performance targets have not been achieved nor were probable of achievement as of the end of the respective periods. These awards and stock options were canceled on March 7, 2023 (see Note 20 to these consolidated financial statements for additional information). Certain stock options to purchase shares of common stock were excluded from the computation of diluted earnings per share for the respective periods because the options’ exercise price was greater than the average market price of the common shares. These stock options and anti-dilutive awards are not included in the dilution calculation, as their inclusion would have the effect of increasing diluted income per share or reducing diluted loss per share. 22. Commitments and Contingent Liabilities: Environmental Contingencies There is a risk of environmental impact in the Company’s manufacturing operations. The Company’s environmental policies and practices are designed to comply with existing laws and regulations and to minimize the possibility of significant environmental impact. The Company is also subject to various other lawsuits and claims with respect to matters such as governmental regulations, labor and other actions arising out of the normal course of business. All claims that are probable and reasonably estimable have been accrued for in the Company’s consolidated financial statements. When these matters are ultimately concluded and determined, the Company believes that there will be no material adverse effect on its consolidated financial position, results of operations or liquidity. The Company has recorded a reserve of $ 1,286 and $ 530 as of December 31, 2025 and 2024, respectively, to address remaining subsurface remedial and wetlands/marsh management activities at the Company’s Martinez, California site. Although currently a sulfuric acid regeneration plant, the site was originally operated by Mountain Copper Company (“Mococo”) as a copper smelter. Also, the site sold iron pyrite to various customers and allowed their customers to deposit waste iron pyrite cinder and slag on the site. The property is adjacent to the now capped former Peyton Slough, where Mococo had a permitted discharge point from its process and the current Peyton Slough. In 1997, the San Francisco Bay Regional Water Quality Control Board (“RWQCB”) required characterization and remediation of the former Peyton Slough for Copper, Zinc and Acidic Soils. Various remediation activities were undertaken and completed, including the excavation of a new Peyton Slough, which is the current site. The site received final concurrence from the Army Corps with respect to the completed work. The RWQCB agreed that Ecoservices has achieved the goals for vegetative cover. The current marsh condition is being sustained by the opening and subsequent closing of the tide gates on a periodic basis. Through facilitation between the Company, the RWQCB and various other governmental and private stakeholders, an alliance was formed and recently culminated in an independent environmental-related settlement agreement between the RWQCB and a company not associated with the facilitation efforts. Under the settlement agreement, another company agreed to fund a Supplemental Environmental Project for the Peyton Slough Marshes Water Quality Improvements and Management Project (Peyton Slough SEP). The Peyton Slough SEP is being managed by the Contra Costa Resource Conservation District and is intended to improve water circulation and water quality within the marshes adjacent to Carquinez Strait, including the Peyton Slough Channel and McNabney Marsh, by automating tide gate operations to improve exchange between Peyton Slough and Carquinez Strait. The project will also assess sediment quality and distribution within the system to evaluate methods of further enhancing water quality and marsh habitat. In addition, the Company has negotiated and is currently in the process of negotiating, modified permits with various governmental agencies, including the RWQCB, for the long-term maintenance of the capped Peyton Slough and the associated levees and berms. F-57 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) As of December 31, 2025 and 2024, the Company has recorded a reserve of $ 296 and $ 216 , respectively, for subsurface remediation, including the Soil Vapor Extraction Project, at the Company’s Dominguez, California site. In the 1980s and 1990s, the EPA and the Los Angeles Regional Water Quality Control Board conducted investigations of the site due to historic chlorinated pesticide and chlorinated solvent use. Soil and groundwater beneath the site were impacted by chlorinated solvents and associated breakdown products, petroleum hydrocarbons, chlorinated pesticides and metals. A Corrective Measures Plan approved in October 2011 requires (1) soil vapor extraction (“SVE”) in affected areas, (2) covering of unpaved areas containing pesticide impacted soil, and (3) annual groundwater monitoring of the perched water-bearing zone. Annual groundwater sampling and soil vapor monitoring indicates that the SVE system has been effective in reducing subsurface contaminant levels. The Company is moving in the direction of rendering the SVE system dormant and potentially closing this matter within the next few years following rebound testing, including the preparation of soil vapor and groundwater cleanup goals as requested by the California Department of Toxic Substances Control. Annual inspections of the now covered areas containing pesticide impacted soil and repairs, as warranted, are expected to continue. As of December 31, 2025 and 2024, the Company has recorded a reserve of $ 45 and $ 37 , respectively, for the ongoing groundwater monitoring efforts associated with the Company’s Hammond, Indiana site. Numerous environmental-related investigations have been conducted at the site, including, but not limited to, under a Voluntary Corrective Action Agreement (“VCAA”) executed by one of the Company’s predecessors (Rhodia Inc.) with the Indiana Department of Environmental Management (“IDEM”) on April 28, 2010 and most recently in accordance with an 2018 Corrective Measures Proposal (“CMP”). Groundwater monitoring has been conducted at the site since 2011 to address chlorinated volatile organic compound (“CVOC”) impacts from a former railcar unloading area in the northern portion of the site. The Company only uses this area for loading virgin sulfuric acid and unloading spent sulfuric acid. The CMP established monitored natural attenuation (“MNA”) as the corrective measure for addressing CVOCs present in groundwater in the northern portion of the site and offsite beneath the adjacent Northern Indiana Commuter Transportation District (“NICTD”) property and a gas station; and has been and continues to be implemented since 2018. In light of increasing CVOC concentrations in one deep perimeter well, the criteria for ceasing monitoring under the CMP has not yet been achieved. The Company plans to meet with IDEM to discuss potential options for closing out this matter. Letters of Credit At December 31, 2025, the Company had outstanding letters of credit of $ 3,230 . Letters of credit are guarantees of payment to third parties. The Company’s letters of credit are used primarily as collateral for various items, including energy and insurance payments. The letters of credit are supported by the Company’s ABL facility. F-58 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) 23. Quarterly Financial Summary (Unaudited): The following tables summarize the Company’s quarterly financial results during the years ended December 31, 2025 and 2024: 2025 First Quarter Second Quarter Third Quarter Fourth Quarter Sales $ 143,109 $ 176,065 $ 204,907 $ 199,434 Gross profit 19,098 40,161 52,075 46,752 Operating (loss) income ( 981 ) 15,780 28,275 21,811 Net (loss) income from continuing operations ( 8,134 ) 5,022 185 9,215 Net income (loss) from discontinued operations, net of tax 4,537 964 ( 79,440 ) ( 3,475 ) Net (loss) income ( 3,597 ) 5,986 ( 79,255 ) 5,740 (Loss) earnings per common share - basic: Continuing operations $ ( 0.07 ) $ 0.04 $ 0.00 $ 0.08 Discontinued operations $ 0.04 $ 0.01 $ ( 0.70 ) $ ( 0.03 ) Net (loss) earnings per share - basic $ ( 0.03 ) $ 0.05 $ ( 0.70 ) $ 0.05 (Loss) earnings per common share - diluted: Continuing operations $ ( 0.07 ) $ 0.04 $ 0.00 $ 0.08 Discontinued operations $ 0.04 $ 0.01 $ ( 0.69 ) $ ( 0.03 ) Net (loss) earnings per share - diluted $ ( 0.03 ) $ 0.05 $ ( 0.69 ) $ 0.05 Weighted average shares outstanding: Basic 117,264,124 116,232,528 113,901,834 113,357,158 Diluted 117,264,124 116,535,060 114,869,273 114,454,479 F-59 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) 2024 First Quarter Second Quarter Third Quarter Fourth Quarter Sales $ 141,602 $ 153,958 $ 153,868 $ 148,867 Gross profit 33,232 42,028 45,135 42,989 Operating income 13,481 21,667 27,543 22,442 Net income from continuing operations 2,048 5,027 14,612 23,817 Net (loss) income from discontinued operations, net of tax ( 827 ) 3,268 ( 361 ) ( 54,236 ) Net income (loss) 1,221 8,295 14,251 ( 30,419 ) Earnings (loss) per common share - basic: Continuing operations $ 0.02 $ 0.04 $ 0.13 $ 0.20 Discontinued operations $ ( 0.01 ) $ 0.03 $ 0.00 $ ( 0.47 ) Net earnings (loss) per share - basic $ 0.01 $ 0.07 $ 0.12 $ ( 0.26 ) Earnings (loss) per common share - diluted: Continuing operations $ 0.02 $ 0.04 $ 0.12 $ 0.20 Discontinued operations $ ( 0.01 ) $ 0.03 $ 0.00 $ ( 0.46 ) Net earnings (loss) per share - diluted $ 0.01 $ 0.07 $ 0.12 $ ( 0.26 ) Weighted average shares outstanding: Basic 116,955,043 116,912,332 116,490,634 116,518,933 Diluted 117,451,149 117,635,289 117,187,054 117,515,453 24. Supplemental Cash Flow Information: The following table presents supplemental cash flow information for the Company, which includes activity from both continuing and discontinued operations: Years ended December 31, 2025 2024 2023 Cash paid during the year for: Income taxes, net of refunds $ 11,048 $ 26,259 $ 22,437 Interest (1) 50,836 48,972 42,081 Non-cash investing activity: Capital expenditures acquired on account but unpaid as of the year end 3,573 4,882 3,427 Non-cash financing activities (2) : Accrued excise tax on share repurchases (Note 8) 392 — 638 (1) Cash paid for interest is shown net of capitalized interest and includes the cash received or paid on the Company’s interest rate cap agreements for the periods presented (see Note 17 to these consolidated financial statements for details). (2) For the supplemental non-cash information on lease liabilities arising from obtaining right-of-use lease assets, see Note 12 to these consolidated financial statements for further information. F-60 Table of Contents ECOVYST INC. AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (Dollars in thousands, except share and per share amounts) 25. Subsequent Events: The Company has evaluated subsequent events since the balance sheet date and determined that there are no additional items to disclose. F-61 Table of Contents SCHEDULE I ECOVYST INC. AND SUBSIDIARIES (PARENT) CONDENSED FINANCIAL INFORMATION CONDENSED STATEMENTS OF (LOSS) INCOME (in thousands) Years ended December 31, 2025 2024 2023 Stock compensation expense $ 12,316 $ 14,043 $ 16,031 Equity in net (income) from subsidiaries 58,810 ( 7,391 ) ( 87,185 ) Net (loss) income ( 71,126 ) ( 6,652 ) 71,154 Other comprehensive income (loss), net of tax: Pension and postretirement benefits 983 855 1,120 Net loss from hedging activities ( 9,081 ) ( 2,644 ) ( 12,126 ) Foreign currency translation 18,776 ( 4,660 ) 4,056 Total other comprehensive (loss) income 10,678 ( 6,449 ) ( 6,950 ) Comprehensive (loss) income $ ( 60,448 ) $ ( 13,101 ) $ 64,204 See accompanying notes to condensed financial statements. F-62 Table of Contents SCHEDULE I ECOVYST INC. AND SUBSIDIARIES (PARENT) CONDENSED FINANCIAL INFORMATION CONDENSED BALANCE SHEETS (in thousands, except share and per share amounts) December 31, 2025 2024 ASSETS Investment in subsidiaries $ 603,440 $ 700,460 Total assets $ 603,440 $ 700,460 LIABILITIES Total liabilities $ — $ — STOCKHOLDERS' EQUITY Common stock ( 0.01 par); authorized shares 450,000,000 ; issued shares 140,872,846 and 140,872,846 on December 31, 2025 and 2024, respectively; outstanding shares 111,805,102 and 116,534,803 on December 31, 2025 and 2024, respectively 1,409 1,409 Preferred stock ( 0.01 par); authorized shares 50,000,000 ; no shares issued or outstanding on December 31, 2025 and 2024, respectively — — Additional paid-in capital 1,108,525 1,106,792 Accumulated deficit ( 248,634 ) ( 177,508 ) Treasury stock, at cost; shares 29,067,744 and 24,338,043 on December 31, 2025 and 2024, respectively ( 261,131 ) ( 222,826 ) Accumulated other comprehensive income (loss) 3,271 ( 7,407 ) Total equity 603,440 700,460 Total liabilities and equity $ 603,440 $ 700,460 See accompanying notes to condensed financial statements. F-63 Table of Contents SCHEDULE I ECOVYST INC. AND SUBSIDIARIES (PARENT) CONDENSED FINANCIAL INFORMATION CONDENSED STATEMENTS OF CASH FLOWS (in thousands) Years ended December 31, 2025 2024 2023 Cash flows from operating activities: Net (loss) income $ ( 71,126 ) $ ( 6,652 ) $ 71,154 Adjustments to reconcile net income to net cash provided by operating activities: Equity in net (income) from subsidiaries 58,810 ( 7,391 ) ( 87,185 ) Stock compensation expense 12,316 14,043 16,031 Net cash provided by operating activities — — — Effect of exchange rate changes on cash and cash equivalents — — — Net change in cash and cash equivalents — — — Cash and cash equivalents at beginning of period — — — Cash and cash equivalents at end of period $ — $ — $ — See accompanying notes to condensed financial statements. F-64 Table of Contents SCHEDULE I ECOVYST INC. AND SUBSIDIARIES (PARENT) CONDENSED FINANCIAL INFORMATION NOTES TO CONDENSED SCHEDULE I 1. Description of Ecovyst Inc. and Subsidiaries Ecovyst Inc. (“Ecovyst” or the “Parent Company”) is a holding company that conducts substantially all of its business operations through its wholly owned subsidiary, Ecovyst Catalyst Technologies LLC. As specified in certain of Ecovyst Catalyst Technologies LLC’s debt agreements, there are restrictions on the ability of Ecovyst Catalyst Technologies LLC to make payments to its stockholder, Ecovyst, on behalf of its equity interests (refer to Note 16 to the Ecovyst consolidated financial statements for further information regarding Ecovyst debt). 2. Basis of Presentation The accompanying condensed Parent Company financial statements are required in accordance with Rule 4-08(e)(3) of Regulation S-X. These condensed financial statements have been presented on a “parent-only” basis and are not the general-purpose financial statements of Ecovyst. Under a parent-only presentation, the Parent Company’s investment in its consolidated subsidiary is recorded based upon its proportionate share of the subsidiary’s net assets, similar to presenting it under the equity method of accounting. Under the equity method, the investment in subsidiary is stated at cost plus contributions and equity in undistributed income (loss) of the subsidiary, less distributions received since the date of acquisition. These parent-only financial statements should be read in conjunction with Ecovyst’s audited consolidated financial statements and the accompanying notes thereto. 3. Stock-Based Compensation Refer to Note 20 of the notes to the Ecovyst consolidated financial statements for a description of stock-based compensation. F-65 Table of Contents Report of Independent Auditors To the Management Committee of Zeolyst International Opinion We have audited the accompanying financial statements of Zeolyst International (the “Partnership”), which comprise the balance sheets as of December 31, 2025 and 2024, and the related statements of operations and accumulated earnings, of changes in partners’ capital and of cash flows for each of the three years in the period ended December 31, 2025, including the related notes (collectively referred to as the “financial statements”). In our opinion, the accompanying financial statements present fairly, in all material respects, the financial position of the Partnership as of December 31, 2025 and 2024, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2025 in accordance with accounting principles generally accepted in the United States of America. Basis for Opinion We conducted our audit in accordance with auditing standards generally accepted in the United States of America (US GAAS). Our responsibilities under those standards are further described in the Auditors' Responsibilities for the Audit of the Financial Statements section of our report. We are required to be independent of the Partnership and to meet our other ethical responsibilities, in accordance with the relevant ethical requirements relating to our audit. We believe that the audit evidence we have obtained is sufficient and appropriate to provide a basis for our audit opinion. Emphasis of Matter As discussed in Note 15 to the financial statements, the Partnership has entered into significant related party transactions with its partners and affiliates of its partners. Our opinion is not modified with respect to this matter. Responsibilities of Management for the Financial Statements Management is responsible for the preparation and fair presentation of the financial statements in accordance with accounting principles generally accepted in the United States of America, and for the design, implementation, and maintenance of internal control relevant to the preparation and fair presentation of financial statements that are free from material misstatement, whether due to fraud or error. In preparing the financial statements, management is required to evaluate whether there are conditions or events, considered in the aggregate, that raise substantial doubt about the Partnership’s ability to continue as a going concern for one year after the date the financial statements are available to be issued. Auditors’ Responsibilities for the Audit of the Financial Statements Our objectives are to obtain reasonable assurance about whether the financial statements as a whole are free from material misstatement, whether due to fraud or error, and to issue an auditors' report that includes our opinion. Reasonable assurance is a high level of assurance but is not absolute assurance and therefore is not a guarantee that an audit conducted in accordance with US GAAS will always detect a material misstatement when it exists. The risk of not detecting a material misstatement resulting from fraud is higher than for one resulting from error, as fraud may involve collusion, forgery, intentional omissions, misrepresentations, or the override of internal control. Misstatements are considered material if there is a substantial likelihood that, individually or in the aggregate, they would influence the judgment made by a reasonable user based on the financial statements. F-66 Table of Contents In performing an audit in accordance with US GAAS, we: • Exercise professional judgment and maintain professional skepticism throughout the audit. • Identify and assess the risks of material misstatement of the financial statements, whether due to fraud or error, and design and perform audit procedures responsive to those risks. Such procedures include examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. • Obtain an understanding of internal control relevant to the audit in order to design audit procedures that are appropriate in the circumstances, but not for the purpose of expressing an opinion on the effectiveness of the Partnership's internal control. Accordingly, no such opinion is expressed. • Evaluate the appropriateness of accounting policies used and the reasonableness of significant accounting estimates made by management, as well as evaluate the overall presentation of the financial statements. • Conclude whether, in our judgment, there are conditions or events, considered in the aggregate, that raise substantial doubt about the Partnership's ability to continue as a going concern for a reasonable period of time. We are required to communicate with those charged with governance regarding, among other matters, the planned scope and timing of the audit, significant audit findings, and certain internal control-related matters that we identified during the audit. /s/ PricewaterhouseCoopers LLP Philadelphia, Pennsylvania February 27, 2026 F-67 Table of Contents ZEOLYST INTERNATIONAL STATEMENTS OF OPERATIONS AND ACCUMULATED EARNINGS (in thousands) Years ended December 31, 2025 2024 2023 Sales $ 263,155 $ 233,079 $ 312,963 Cost of goods sold 184,615 157,139 206,583 Gross profit 78,540 75,940 106,380 Selling, general and administrative expenses (SG&A) 37,942 40,176 37,203 Other operating (income) expense, net (193) 540 (217) Operating income 40,791 35,224 69,394 Interest income, net (947) (705) (453) Other expense (income), net 2,338 2,557 (497) Net income 39,400 33,372 70,344 Accumulated earnings at beginning of year 234,379 277,007 262,663 Dividends paid (80,000) (76,000) (56,000) Accumulated earnings at end of year $ 193,779 $ 234,379 $ 277,007 See accompanying notes to financial statements. F-68 Table of Contents ZEOLYST INTERNATIONAL BALANCE SHEETS (in thousands) December 31, 2025 December 31, 2024 ASSETS Cash $ 26,163 $ 35,267 Trade receivables, net: Receivables from third parties 23,274 41,217 Receivables from affiliates 4,017 3,666 Inventories 127,163 123,428 Other current assets 1,246 1,942 Total current assets 181,863 205,520 Property, plant and equipment, net 87,558 96,015 Intangible assets 1,800 2,850 Right-of-use lease asset 5,449 5,581 Other long-term assets 8,609 9,529 Total assets $ 285,279 $ 319,495 LIABILITIES Trade accounts payable $ 8,261 $ 9,996 Accounts payable to affiliates 21,257 13,336 Operating lease liability—current 136 131 Accrued liabilities 1,603 1,273 Total current liabilities 31,257 24,736 Operating lease liability—noncurrent 5,313 5,450 Revolver — — Total liabilities 36,570 30,186 Commitments and contingencies (Note 14) PARTNERS’ CAPITAL Contributed capital 54,930 54,930 Accumulated earnings 193,779 234,379 Net partners’ capital 248,709 289,309 Total liabilities and partners' capital $ 285,279 $ 319,495 See accompanying notes to financial statements. F-69 Table of Contents ZEOLYST INTERNATIONAL STATEMENTS OF CHANGES IN PARTNERS’ CAPITAL (in thousands) Contributed capital Accumulated earnings Net partners' capital Ecovyst Inc.: Balance, December 31, 2022 $ 27,465 $ 131,332 $ 158,797 Dividends paid (28,000) (28,000) Net income 35,172 35,172 Balance, December 31, 2023 $ 27,465 $ 138,504 $ 165,969 Dividends paid (38,000) (38,000) Net income 16,686 16,686 Balance, December 31, 2024 $ 27,465 $ 117,190 $ 144,655 Dividends paid $ (40,000) $ (40,000) Net income $ 19,700 $ 19,700 Balance, December 31, 2025 (1) $ 27,465 $ 96,890 $ 124,355 Shell Catalysts & Technologies: Balance, December 31, 2022 $ 27,465 $ 131,332 $ 158,797 Dividends paid (28,000) (28,000) Net income 35,172 35,172 Balance, December 31, 2023 $ 27,465 $ 138,504 $ 165,969 Dividends paid (38,000) (38,000) Net income 16,686 16,686 Balance, December 31, 2024 $ 27,465 $ 117,190 $ 144,655 Dividends paid $ (40,000) $ (40,000) Net income $ 19,700 $ 19,700 Balance, December 31, 2025 $ 27,465 $ 96,890 $ 124,355 Total partners' capital at December 31, 2023 $ 54,930 $ 277,007 $ 331,937 Total partners' capital at December 31, 2024 $ 54,930 $ 234,379 $ 289,309 Total partners' capital at December 31, 2025 $ 54,930 $ 193,779 $ 248,709 (1) Partners’ capital transferred from Ecovyst Inc. to Technip Energies N.V. as a result of Ecovyst completing the sale of its Advanced Materials & Catalysts business on December 31, 2025 (see Note 1 for additional information). See accompanying notes to financial statements. F-70 Table of Contents ZEOLYST INTERNATIONAL STATEMENTS OF CASH FLOWS (in thousands) Years ended December 31, 2025 2024 2023 Cash flows from operating activities: Net income $ 39,400 $ 33,372 $ 70,344 Adjustments to reconcile net income to net cash provided by operating activities: Depreciation and amortization 16,925 15,937 16,282 Loss on sale or disposal of capital assets 3 21 79 Amortization of deferred financing fees 33 33 33 Net change in returns allowance — 135 — Net change in inventory reserve 77 (1,520) 1,319 Other (37) (2,562) (3,597) Working capital changes that provided (used) cash: Receivables, including affiliates 17,592 68,804 (25,010) Inventories (3,812) (4,582) 15,292 Other current assets 663 (192) 90 Accounts payable, including affiliates 5,629 1,443 (1,352) Other current liabilities 335 (2,783) (198) Net cash provided by operating activities 76,808 108,106 73,282 Cash flows from investing activities: Purchases of property, plant and equipment (5,912) (5,256) (4,273) Net cash used in investing activities (5,912) (5,256) (4,273) Cash flows from financing activities: Draw down of revolver — 5,000 20,000 Payments on revolver — (5,000) (30,000) Payments of cash dividends (80,000) (76,000) (56,000) Net cash used in financing activities (80,000) (76,000) (66,000) Net change in cash (9,104) 26,850 3,009 Cash at beginning of period 35,267 8,417 5,408 Cash at end of period $ 26,163 $ 35,267 $ 8,417 Non-cash investing activity: Capital expenditures acquired on account but unpaid $ 2,437 $ 1,880 $ 1,518 See accompanying notes to financial statements. F-71 Table of Contents ZEOLYST INTERNATIONAL NOTES TO FINANCIAL STATEMENTS (in thousands) 1. Organization: Background Zeolyst International is a Kansas general partnership (“Partnership”) by and formerly between Ecovyst Catalyst Technologies LLC (“Ecovyst”) and Shell Catalysts & Technologies (formerly referred to as CRI Zeolites Inc. (“CRI”)), a Royal Dutch Shell affiliate (collectively, the “Partners”) formed pursuant to a Partnership Agreement dated February 1, 1988, as amended (“the Agreement”). Pursuant to a Contribution, Assignment, and Assumption Agreement dated July 29, 2021 (the “Contribution Agreement”) by and between Ecovyst and PQ Corporation (“PQ”), PQ transferred and Ecovyst assumed PQ’s interest in the Partnership and the Agreement. The percentage interests as December 31, 2025 and 2024 are as follows: December 31, 2025 2024 Technip Energies N.V. (1) 50% Ecovyst 50% Shell Catalysts & Technologies 50% Shell Catalysts & Technologies 50% (1) Reflects the change in ownership as a result of Ecovyst completing the sale of its Advanced Materials & Catalysts business on December 31, 2025 (see below). The Partnership was formed pursuant to the Kansas Uniform Partnership Act. The Agreement specifies that the partners share equally in capital contributions. The Agreement states that the profits and losses of the Partnership will be allocated in accordance with the partners’ interests in the Partnership. The intent of the Partnership is to develop, manufacture, and sell zeolites and zeolite-containing catalysts. The Partnership has significant transactions with its partners and related affiliates. See Note 15 for further information on related party transactions. Recent Developments On December 31, 2025, Ecovyst completed the sale of its Advanced Materials & Catalysts business, which included its equity interest in the Partnership, to Technip Energies N.V. for a purchase price of $556,000. As a result of this transaction, Technip Energies N.V. succeeded Ecovyst as a partner in Zeolyst International, subject to the terms of the Partnership and the Agreement. 2. Partnership Business: The Partnership manufactures zeolites and zeolytic catalysts that are used by refiners to capture impurities in the processing of petroleum based feed streams while increasing value. The selectivity and activity of zeolites used for this purpose can improve yields and have a general life cycle of 3-4 years. As a result, a significant portion of the Partnership’s customer base tends to change on an annual basis. A significant percentage of the base materials purchased for the Partnership’s manufacturing process are acquired from related parties. In addition, a significant portion of the Partnership’s sales are transacted through Shell Catalysts & Technologies (“Shell”). The Partnership compensates Shell with a 2% sales commission or royalty fee on specific sales transactions. 3. Summary of Significant Accounting Policies: These financial statements have been prepared in accordance with generally accepted accounting principles. These financial statements are accounted for on a historical cost basis and do not reflect the results of any purchase accounting adjustments recorded in the Partners’ respective financial statements. Cash and Cash Equivalents. Cash and cash equivalents include investments with original terms to maturity of 90 days or less from the time of purchase. F-72 Table of Contents ZEOLYST INTERNATIONAL NOTES TO FINANCIAL STATEMENTS (in thousands) Restricted Cash. Restricted cash, which is restricted as to withdrawal or usage, is classified separately from cash and cash equivalents on the Partnership’s balance sheets. The Partnership had no restricted cash balances as of December 31, 2025 and 2024. Trade Accounts Receivable and Allowance for Doubtful Accounts. Trade accounts receivable are recorded at the invoiced amount and do not bear interest. The Partnership maintains allowances for doubtful accounts for estimated losses resulting from the inability of its customers to make required payments. Allowances for doubtful accounts are based on historical experience and known factors regarding specific customers. If the financial condition of the Partnership’s customers were to deteriorate, resulting in an impairment of their ability to make payments, additional allowances would be required. Account balances are charged off against the allowance when it is probable the receivable will not be recovered. Inventories. Inventories are stated at the lower of cost or net realizable value, valued on the first-in, first-out (“FIFO”) method. The Partnership establishes reserves for slow-moving and obsolete inventory. Property, Plant and Equipment. Property, plant, and equipment are carried at cost and include expenditures for new facilities and major renewals and betterments. Interest is capitalized on capital projects as applicable. Maintenance, repairs and minor renewals are charged to expense as incurred. When assets are sold or otherwise disposed of, the related cost and accumulated depreciation are removed from the accounts, and any resulting gain or loss is included in the results of operations. Depreciation is generally provided on the straight-line method based on estimated useful lives of the assets, ranging up to 33 years for buildings and improvements and 10 years for machinery and equipment. We perform an impairment review of property, plant and equipment and other long-lived assets when events and circumstances indicate that those assets may be impaired by comparing the carrying amount of the assets to their fair value. Fair value is determined using quoted market prices where available, or other techniques including discounted cash flows. The Partnership’s estimates of future cash flows involve assumptions concerning future operating performance, economic conditions, and technological changes that may affect the future useful lives of the assets. Leases . The Partnership has an evergreen land lease agreement with a remaining lease term of 26 years as of December 31, 2025. Accounting Standards Codification Topic 842, Leases (“ASC 842”) , does not provide definitive guidance as to determining the length of evergreen leasing arrangements. As such, the Partnership estimated the term of the lease agreement to be commensurate with the estimated useful life of the buildings located on the land that is being leased. Upon adoption of ASC 842 on January 1, 2019, the Partnership assigned a 33 year life to the land lease agreement. When the Partnership enters into an arrangement, at inception, the Partnership determines if the arrangement contains a lease and whether that lease meets the classification criteria of a finance or operating lease. The Partnership’s lease arrangement only contains lease components. The Partnership’s lease agreement does not contain any material residual value guarantees or material restrictive covenants. The Partnership recognizes a right-of-use lease asset and lease liability at the lease commencement date based on the present value of the remaining lease payments over the lease term. The Partnership was unable to readily determine the discount rate implicit in the lease agreement in accordance with the policy. As such, the Partnership utilized its incremental borrowing rate over the relevant lease term, which is the rate of interest that it would have to pay to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. Short-term leases, which have an initial term of twelve months or less, are not recorded on the Partnership’s balance sheet. Lease expense for the operating lease is recognized on a straight-line basis over the lease term. The amortization expense component of the right-of-use lease asset is included in cost of goods sold and in selling, general and administrative expenses on the accompanying statements of operations and accumulated earnings. Intangibles and Other Long-term Assets. Other long-term assets primarily include intangible assets, at cost and spare parts. In May 2017, the Partnership made a $6,500 strategic investment for license of materials-based solutions for catalytic and separations processes. In April 2018, the Partnership made a $4,000 strategic investment to buy down F-73 Table of Contents ZEOLYST INTERNATIONAL NOTES TO FINANCIAL STATEMENTS (in thousands) royalty obligations related to certain license agreements. The Partnership amortizes these intangible assets over a ten-year period and includes the expense in selling, general and administrative expenses on the accompanying statements of operations and accumulated earnings. The Partnership incurred intangible asset related amortization expense of $1,050 for the years ended December 31, 2025, 2024 and 2023, respectively, related to these investments. Estimated future aggregate amortization expense of intangible assets is as follows: Year Amount 2026 $ 1,050 2027 617 2028 133 2029 — 2030 — Thereafter — Total estimated future aggregate amortization expense $ 1,800 Revenue Recognition. In determining the appropriate amount of revenue to be recognized as the Partnership fulfills its obligations under its agreements, the Partnership performs the following steps: (i) identification of the contract with the customer; (ii) determination of whether the promised goods or services are performance obligations, including whether they are distinct in the context of the contract; (iii) measurement of the transaction price; (iv) allocation of the transaction price to the performance obligations based on estimated selling prices; and (v) recognition of revenue when (or as) the Partnership satisfies each performance obligation. The Partnership identifies a contract when an agreement with a customer creates legally enforceable rights and obligations, which occurs when a contract has been approved by both parties, the parties are committed to perform their respective obligations, each party’s rights and payment terms are clearly identified, commercial substance exists and it is probable that the Partnership will collect the consideration to which it is entitled. The Partnership may recognize revenue from bill-and-hold arrangements initiated by a customer. Under these bill-and-hold arrangements, a customer pays for the goods but does not take physical possession immediately. The Partnership considers satisfaction of performance obligations when they have finished manufacturing the products based on the agreed upon specifications in accordance with the order. These products are custom made to each customer’s specifications and cannot be made available for use with another customer’s order. Once the goods have been segregated in a designated space in the warehouse and the customer has been invoiced, title to the goods and risk of loss has transferred to the customer. The customers have access to their products to inspect and can take possession prior to the scheduled delivery dates. The Partnership may offer rebates to customers who have reached a specified volume of optional purchases. The Partnership recognizes rebates given to customers as a reduction of revenue based on an allocation of the cost of honoring rebates earned and claimed to each of the underlying revenue transactions that result in progress by the customer toward earning the rebate. Rebates are recognized at the time revenue is recorded. The Partnership measures the rebate obligation based on the estimated amount of sales that will result in a rebate at the adjusted sales price per the respective sales agreement. The Partnership recognizes revenue when all essential elements of the sales order have shipped and both title and risk of loss has passed to the customer. Hydrocracking and specialty catalyst orders are typically filled by a number of individual shipments, and those shipments may span the end of a fiscal quarter or year. If a portion of the order has not shipped and it is essential to the functionality of the customer’s end use, revenue is recognized when the order is completed. A shipment is considered essential if each individual shipment has no value to the customer on a stand-alone basis and if the remaining shipment is not considered inconsequential and perfunctory. The Partnership currently reserves approximately 2% of the Hydrocracking catalyst sales due to a clause in the contract that allows customers to return up to 5% of the unused products they purchase within 90 days, and based on historical experience. The total sales returns reserve was $1,188 for the years ended December 31, 2025 and 2024. F-74 Table of Contents ZEOLYST INTERNATIONAL NOTES TO FINANCIAL STATEMENTS (in thousands) Shipping and Handling. Amounts billed to a customer in a sale transaction related to shipping and handling, if any, represent revenues earned for the goods provided and are classified as revenue. Costs related to shipping and handling of products shipped to customers are classified as cost of goods sold. See Note 5 for disclosures regarding the recognition of revenue for shipping and handling costs that are billed to customers. Research and Development: Research and development costs of $12,160, $17,667 and $15,388 for the years ended December 31, 2025, 2024 and 2023, respectively, were expensed as incurred and reported in selling, general and administrative expenses in the accompanying statements of operations and accumulated earnings. Costs include salaries, contractor fees, building costs, utilities and administrative expenses. Foreign Exchange Transactions. The functional currency of the Partnership is the U.S. Dollar. The Partnership enters into transactions that are denominated in other currencies. Gains and losses on foreign currency transactions are included in other (income) / expense, net on the accompanying statements of operations and accumulated earnings. Foreign exchange (gain) loss of $(377), $1,296 and $(67) were recognized for the years ended December 31, 2025, 2024 and 2023, respectively. Fair Value Measurements. The Partnership’s financial assets and liabilities are reflected in the financial statements at amortized cost which approximates fair market value. Fair value is defined as the price at which an asset could be exchanged in a current transaction between willing market participants. A liability’s fair value is defined as the amount that would be paid to transfer the liability to a market participant, not the amount that would be paid to settle the liability with a creditor. The Partnership’s cash balances approximate fair value due to their short-term maturity. Use of Estimates. The preparation of the Partnership’s financial statements in conformity with generally accepted accounting principles requires management to make estimates that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates. 4. Recently Issued Accounting Standards: In July 2025, the Financial Accounting Standards Board (“FASB”) issued guidance related to the estimation of expected credit losses for current accounts receivable and current contract assets that arise from transactions accounted for under ASC 606 . This new guidance introduces a practical expedient for entities that assumes that current conditions as of the balance sheet date do not change for the remaining life of the asset. The new guidance is effective for fiscal years beginning after December 15, 2025 and interim periods within those fiscal years, with early adoption permitted. The Partnership is currently evaluating the impact of this guidance. In November 2024, FASB issued guidance requiring public business entities to disclose additional information on the nature of certain expenses presented in the income statement. The new guidance requires tabular disclosure of significant expense categories and qualitative descriptions for amounts not disaggregated from relevant expense categories. Public business entities are required to define selling expenses and disaggregate the components. The new guidance is effective for fiscal years beginning after December 15, 2026 and interim periods within fiscal years beginning after December 15, 2027, with early adoption permitted. The requirements must be applied prospectively however public business entities have the option to apply the guidance retrospectively. The disclosure will be implemented as required for the fiscal year ended December 31, 2027. The Partnership is currently evaluating the impact of this guidance. F-75 Table of Contents ZEOLYST INTERNATIONAL NOTES TO FINANCIAL STATEMENTS (in thousands) 5. Revenue from Contracts with Customers: The Partnership applies the five-step revenue recognition model to each contract with its customers. Evidence of a contract between the Partnership and its customers may take the form of a master service agreement (“MSA”), a MSA in combination with an underlying purchase order, a combination of a pricing quote with an underlying purchase order or an individual purchase order received from a customer. The Partnership and certain of its customers enter into MSAs that establish the terms, including prices, under which orders to purchase goods may be placed. In cases where the MSA contains a distinct order for goods or contains an enforceable minimum quantity to be purchased by the customer, the Partnership considers the MSA to be evidence of a contract between the Partnership and its customer as the MSA creates enforceable rights and obligations. In cases where the MSA does not contain a distinct order for goods, the Partnership’s contract with a customer is the purchase order issued under the MSA. Customers of the Partnership may also negotiate orders via pricing quotes, which typically detail product pricing, delivery terms and payment information. When a customer procures goods under this method, the Partnership considers the combination of the pricing quote and the purchase order to create enforceable rights and obligations. Absent either a MSA or pricing quote, the Partnership considers an individual purchase order to create enforceable rights and obligations. The Partnership identifies a performance obligation in a contract for each promised good that is separately identifiable from other promises in the contract and for which the customer can benefit from the good. The Partnership’s contracts have a single performance obligation, which is the promise to transfer individual goods to the customer. Single performance obligations are satisfied according to the shipping terms noted within the MSA or purchase order. As described above, the Partnership’s MSAs with its customers may outline prices for individual products or contract provisions. Revenue from product sales are recorded at the sales price, which includes estimates of variable consideration for which reserves are established and which result from discounts, returns or other allowances that are offered within contracts between the Partnership and its customers. The Partnership recognizes revenues when performance obligations under the terms of a contract with its customer are satisfied, which generally occurs at a point in time by transferring control of a product to the customer. The Partnership determines the point in time when a customer obtains control of a product and the Partnership satisfies the performance obligation by considering factors including when the Partnership has a right to payment for the product, the customer has legal title to the product, the Partnership has transferred possession of the product, the customer has assumed the risks and rewards of ownership of the product and the customer has accepted the product. Revenue is measured as the amount of consideration the Partnership expects to receive in exchange for transferring goods. The Partnership does not have any significant payment terms as payment is received at, or shortly after, the point of sale. Contract Assets and Liabilities A contract asset is a right to consideration in exchange for goods that the Partnership has transferred to a customer when that right is conditional on something other than the passage of time. A contract liability exists when the Partnership receives consideration in advance of performance obligations. The Partnership has not recorded any contract assets or contract liabilities on its balance sheet as of December 31, 2025 and 2024. Practical Expedients and Accounting Policy Elections The Partnership has elected to use certain practical expedients and has made certain accounting policy elections as permitted under the revenue recognition guidance. Certain of the Partnership’s contracts with customers are based on an individual purchase order; thus, the duration of these contracts are for one year or less. The Partnership has made an accounting policy election to omit certain disclosures related to remaining performance obligations for contracts which have an initial term of one year or less. When the Partnership performs shipping and handling activities after the transfer of control to the customer (e.g. when control transfers prior to delivery), they are considered fulfillment activities as opposed to separate performance obligations, and the Partnership recognizes revenue upon the transfer of control to the customer. Accordingly, the costs associated with these shipping and handling activities are accrued when the related revenue is recognized under the Partnership’s policy election. The Partnership expenses incremental costs of obtaining a contract as incurred if the expected amortization period of the asset that the Partnership would have recognized is one year or less. Sales, value added and other taxes the Partnership collects concurrent with revenue producing activities are excluded from revenues. F-76 Table of Contents ZEOLYST INTERNATIONAL NOTES TO FINANCIAL STATEMENTS (in thousands) Disaggregated Revenue The following table disaggregates the Partnership’s sales by end use for the years ended December 31, 2025, 2024 and 2023: Years ended December 31, 2025 2024 2023 Clean fuels, emission control & other $ 205,064 $ 180,506 $ 254,066 Polyethylene, polymers & engineered plastics 58,091 52,573 58,897 Total $ 263,155 $ 233,079 $ 312,963 6. Trade Accounts Receivable and Allowance for Doubtful Accounts: The components of trade receivables, net are as follows: December 31, 2025 2024 Trade accounts receivable $ 28,479 $ 46,071 Allowance for doubtful accounts (1,188) (1,188) Trade receivables, net $ 27,291 $ 44,883 7. Inventories: Inventories were classified as follows: December 31, 2025 2024 Finished products and work in process $ 121,067 $ 116,593 Raw materials and containers 6,096 6,835 Total inventories $ 127,163 $ 123,428 F-77 Table of Contents ZEOLYST INTERNATIONAL NOTES TO FINANCIAL STATEMENTS (in thousands) 8. Property, Plant and Equipment: A summary of property, plant and equipment, at cost, and related accumulated depreciation is as follows: December 31, 2025 2024 Buildings and improvements $ 71,089 $ 70,265 Machinery and equipment 226,153 222,162 Construction in progress 4,331 2,819 301,573 295,246 Less: accumulated depreciation (214,015) (199,231) Total property, plant and equipment, net $ 87,558 $ 96,015 Depreciation expense was $14,926, $14,871 and $15,217 for the years ended December 31, 2025, 2024 and 2023, respectively. Disposal of assets reduced gross property, plant and equipment by $145, $610 and $521, respectively with a loss of $3, $21 and $79 for the years ended December 31, 2025, 2024 and 2023, respectively. 9. Leases: Operating lease costs of $310 are included in cost of goods sold on the accompanying statements of operations and accumulated earnings for the years ended December 31, 2025, 2024 and 2023, respectively. Cash payments on operating leases included in operating cash flows were $310 for the years ended December 31, 2025, 2024 and 2023, respectively. The remaining lease term is 26 years with a weighted average discount rate of 3.25%. The current portion of the lease liability is included on the Partnership’s balance sheets in other current liabilities. There were no finance lease costs for the year ended December 31, 2025. Maturities of lease liabilities as of December 31, 2025 are as follows: Year Operating Lease 2026 $ 310 2027 310 2028 310 2029 310 2030 310 Thereafter 6,509 Total lease payments 8,059 Less: Interest (2,610) Total lease liabilities $ 5,449 F-78 Table of Contents ZEOLYST INTERNATIONAL NOTES TO FINANCIAL STATEMENTS (in thousands) 10. Accrued Liabilities: A summary of accrued liabilities is as follows: December 31, 2025 2024 Royalties and license fees $ 578 $ 763 Commissions 44 6 Rebates 191 91 Property tax 239 238 Other 551 175 $ 1,603 $ 1,273 11. Revolver: In March 2016, the Partnership entered into a five-year revolving line of credit facility of $60,000, which carries an initial interest rate of LIBOR or the base rate plus an interest margin of 0.75% per annum. In May 2020, this agreement was amended to extend the term to May 25, 2022. In November 2021, this agreement was amended again to extend the term to November 29, 2026. The interest rate on the facility was LIBOR or the base rate plus an interest margin of 1.00% per annum. In March 2023, the Partnership amended the revolving line to replace LIBOR with SOFR as the benchmark interest rate. Following this amendment, the revolving line of credit facility bears interest at an adjusted term SOFR rate or the base rate plus an interest margin of 1.00% per annum. As of December 31, 2025, availability under this agreement was $60,000. A commitment fee is paid to the bank for this agreement. The revolving credit agreement contains certain restrictions and covenants that require the Partnership to maintain a minimum partners’ equity, as defined, of $200,000 plus 10% of net income, and a minimum EBITDA of $40,000 on a last twelve month basis measured quarterly. The Partnership was in compliance with all covenants during 2025. Cash payments for interest were approximately $150, $174 and $157 for the years ended December 31, 2025, 2024 and 2023, respectively. The fair value of a financial instrument is the amount at which the instrument could be exchanged in a current transaction. The carrying amount of the revolving line of credit approximates fair value because it is a short term liquidity tool to fund operations, which is drawn down and paid back with cash generated from operations. F-79 Table of Contents ZEOLYST INTERNATIONAL NOTES TO FINANCIAL STATEMENTS (in thousands) 12. Partners’ Contributions: In accordance with the Agreement, in the event that cash flow from operations is insufficient to meet the Partnership’s requirements, following a majority vote by the Management Committee of the Partnership to request capital from the partners, the partners will provide additional capital to enable the Partnership to meet its obligations. No such contributions were made during the years ended December 31, 2025, 2024 or 2023 as the Partnership had the ability to finance operations through cash flow from operations and borrowings under the Partnership’s revolving line of credit facility. 13. Income Taxes: As a partnership, Zeolyst International is not liable for the payment of taxes on income in the U.S. Net income and losses are allocated to the respective partners on an annual basis, and it is the partners’ responsibility to pay income taxes, if any, thereon according to their respective tax positions. 14. Commitments and Contingent Liabilities: In 1998, the Partnership entered into a ten year tolling agreement (“the Tolling Agreement”) with Shell, a related party, for the manufacture of specialty extruded products. Effective January 2004, the 1998 Tolling Agreement was replaced by a new evergreen ten-year tolling agreement. Both parties can terminate this agreement without cause with twenty-four months notice. By letter dated January 19, 2024, Shell provided a notice of termination of the Tolling Agreement effective twenty-four months from the date of such letter. The Tolling Agreement terminated effective December 30, 2025. The Partnership entered into a new ten-year tolling agreement with Shell effective December 31, 2025, which contained updates to certain terms and conditions from the original Tolling Agreement. The Partnership pays Shell for materials utilized plus a daily charge rate based on the actual days of production. This charge is included in cost of goods sold and totaled $45,561, $27,610 and $28,698 for the years ended December 31, 2025, 2024 and 2023, respectively. In addition, for certain capital expenditures, that are beneficial to the Partnership, the parties will mutually agree on future adjustments to the daily charge rates or propose an alternative method of the Partnership’s contribution to those costs. 15. Related Party Transactions: The Partnership maintains certain policies and procedures for the review, approval, and ratification of related party transactions. All significant relationships and transactions are separately identified by management if they meet the definition of a related party or a related party transaction. Related party transactions include transactions that occurred during the year, in which the Partnership was or will be a participant and which any related person had or will have a direct or indirect material interest. Due to the nature of the Partnership, material related party transactions are identified on a transaction-based approach. The types of transactions identified and reviewed include, but are not limited to, sales of products, purchases of inventory, tolling costs, sales and marketing costs, research and development and management-related fees. All related party transactions are reviewed, approved and documented by the appropriate level of the Partnership’s management in accordance with these policies and procedures. F-80 Table of Contents ZEOLYST INTERNATIONAL NOTES TO FINANCIAL STATEMENTS (in thousands) Ecovyst Pursuant to the Contribution Agreement, PQ transferred and Ecovyst assumed PQ’s interest in a lease agreement by and between PQ and the Partnership dated February 1, 1988 (the “Lease”) pursuant to which the Partnership leases certain land used in its Kansas City production facilities, and PQ transferred to Ecovyst the land underlying the Partnership’s Kansas City production facility. The Lease, which has been recorded as an operating lease, provided for rental payments of $310 for the years ended December 31, 2025, 2024 and 2023, respectively. The rent expense is included in the cost of goods sold line item in the accompanying statements of operations and accumulated earnings. The term of the Lease continues as long as the agreement is in effect. The Partnership purchases certain of its raw materials from Ecovyst and is charged for various manufacturing costs incurred at the Ecovyst Kansas City production facility. The amount of these costs charged to the Partnership by Ecovyst during the years ended December 31, 2025, 2024 and 2023 were $19,553, $17,315 and $20,594, respectively. These costs are a component of production costs and are included in the cost of goods sold line item in the accompanying statements of operations and accumulated earnings when the inventory is sold. Certain administrative, marketing, engineering, management-related and research and development services are provided to the Partnership by Ecovyst. During the years ended December 31, 2025, 2024 and 2023, the Partnership was charged by Ecovyst $16,832, $17,203 and $14,758, respectively, for these services. These amounts are included in the selling, general and administrative line item in the accompanying statements of operations and accumulated earnings. In addition, certain product demonstration costs of $1,058, $1,029 and $1,819 during the years ended December 31, 2025, 2024 and 2023, respectively, were recorded in the cost of goods sold line of the accompanying statements of operations and accumulated earnings. The Partnership recognized an immaterial amount of sales to Ecovyst for the year ended December 31, 2025, no sales to Ecovyst for the year ended December 31, 2024 and $236 sales to Ecovyst during the year ended December 31, 2023. As of December 31, 2025 and 2024, the accounts payable to affiliates consisted of $3,917 and $2,794 due to Ecovyst. As of December 31, 2025 and 2024, there were no trade receivables due from Ecovyst. In December 2013 and annually thereafter, Ecovyst and the Partnership entered into ten year real estate tax abatement agreements with the Unified Government of Wyandotte County in Kansas City, Kansas (the “Unified Government”). The agreements utilize an Industrial Revenue Bond (“IRB,” “IRBs”) financing structure to achieve a 75% real estate tax abatement on the value of the improvements that were constructed during the expansion of the then-current fiscal year to Ecovyst and the Partnership’s facilities at the jointly-operated Kansas City, Kansas plant. The IRB financing structure requires Ecovyst to lease its rights to the facility improvements to the Unified Government, which leases the improvements back to Ecovyst. Ecovyst’s rental payments under the sub-leases of the improvements are equal to the amount of the interest payable on the IRBs that the Unified Government sells to Ecovyst. Ecovyst’s sublease payment obligations and the IRB interest payment receivables have been presented net, as the sublease rental payment obligations and the IRB interest payment receivables meet the criteria for right of set off conditions under GAAP. As described in Note 1, on December 31, 2025, Ecovyst completed the sale of its Advanced Materials & Catalysts segment, which included its equity interest in the Partnership, to Technip Energies N.V. As a result of this transaction, Ecovyst is no longer a related party of the Partnership as of December 31, 2025. Shell Catalysts & Technologies Shell Catalysts & Technologies include CRI, Criterion, Shell Development Company, Shell Research and Technology Center-Amsterdam, CRI Center Marketing Asia Pacific, Shell International Oil Products, CRI Belgium, CRI Technology Services and Royal Dutch Shell affiliates. As described in Note 2, a significant portion of the Partnership’s sales are transacted through Shell. During the years ended December 31, 2025, 2024 and 2023, the Partnership recognized sales transacted through Shell of $153,782, $101,223 and $133,618, respectively. The Partnership purchases certain of its raw materials and is charged for tolling, customer distribution and packaging costs incurred by Shell. The amount of these costs charged to the Partnership during the years ended December 31, 2025, 2024 and 2023 were $47,223, $29,502 and $32,282, respectively. These costs are a component of production costs and are included in the cost of goods sold line item in the accompanying statements of operations and accumulated earnings when the inventory is sold. Certain engineering, management-related, broker-related, and research and development services are provided to the Partnership by Shell. During the years ended December 31, 2025, 2024 and 2023, the Partnership was charged F-81 Table of Contents ZEOLYST INTERNATIONAL NOTES TO FINANCIAL STATEMENTS (in thousands) $18,661, $23,388 and $20,699, respectively, for these services. These amounts are included in the selling, general and administrative line item in the accompanying statements of operations and accumulated earnings. Shell constructed a manufacturing asset at its facility wherein the Partnership agreed to share the cost of construction as both parties benefit from the associated asset. The asset was placed in service in 2024 and is being depreciated using the straight-line method over its estimated useful life. As of December 31, 2025, the balance of this asset amounted to $8,370, and is recorded in other long-term assets on the balance sheet. Depreciation expense related to this asset is $939 for the year ended December 31, 2025. As of December 31, 2025 and 2024, the accounts payable to affiliates balance consisted of $6,814 and $5,770, respectively, due to Shell. Included in trade accounts receivable as of December 31, 2025 and 2024 was $4,017 and $3,666, respectively, of receivables related to sales transacted through Shell, as described above. Zeolyst C.V. Zeolyst C.V. is a limited partnership formed in 1993 pursuant to a joint venture agreement between PQ Zeolites B.V. and Shell for the purpose of the production of Zeolite powders. The Partnership entered into an agreement with Zeolyst C.V. to purchase Zeolite powders manufactured by Zeolyst C.V. Under the terms of the agreement, products manufactured by Zeolyst C.V. are supplied solely to the Partnership. The Partnership has performed a qualitative and quantitative analysis and concluded that for Zeolyst C.V. for which it holds a variable interest but will not absorb a majority of the expected losses or residual returns, the Partnership is not the primary beneficiary and therefore, this VIE was not consolidated in the Partnership’s financial statements. The Partnership has no unfunded commitments or guarantees as a result of its involvement with Zeolyst C.V. The total carrying value of assets and liabilities for Zeolyst C.V was $121,562 and $6,477 as of December 31, 2025 and was $105,242 and $5,484 as of December 31, 2024, respectively. The Partnership currently does not have any exposure to any losses by Zeolyst C.V. The Partnership has purchased $53,894, $49,585 and $48,906 through the sales agreement during the years ended December 31, 2025, 2024 and 2023, respectively. These costs are a component of production costs and are included in the cost of goods sold line item in the accompanying statements of operations and accumulated earnings when the inventory is sold. There were no accounts receivable from affiliates due from Zeolyst C.V. as of December 31, 2025 and 2024. There were $10,526 of accounts payable due to Zeolyst C.V. as of December 31, 2025 and $4,772 of accounts payable due to Zeolyst C.V. as of December 31, 2024. 16. Subsequent Events: The Partnership has evaluated subsequent events from the balance sheet date through February 27, 2026 and determined there are no further items to disclose. F-82