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Trinseo PLC_December 31, 2025

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

For the fiscal year ended: December 31, 2025

For the transition period from to

Commission File Number: 001-36473

Trinseo PLC

(Exact name of registrant as specified in its charter)

Ireland N/A

440 East Swedesford Road, Suite 301

Wayne, PA19087

(Address of Principal Executive Offices)

(610) 240-3200

(Registrant’s telephone number)

Securities registered pursuant to Section 12(b) of the Act:

Title of Each Class Trading Symbol Name of Each Exchange on Which Registered

Ordinary Shares, par value $0.01 per share TSE New York Stock Exchange*

Securities registered pursuant to Section 12(g) of the Act:

None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes ☐No☒

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes ☐No☒

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes☒ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes☒ No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Large accelerated filer ☐ Accelerated filer ☒

Non-accelerated filer ☐ Smaller reporting company ☐ Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant has filed a report on and attestation to its management's assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. ☒

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements. ☐

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant’s executive officers during the relevant recovery period pursuant to §240.10D-1(b). ☐

Indicate by check mark whether the Company is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ☒

As of March 5, 2026, there were 36,559,868shares of the registrant’s ordinary shares outstanding.

The aggregate market value of the voting and non-voting shares of the registrant held by non-affiliates of Trinseo PLC computed by reference to the closing price of the registrant’s common shares on the New York Stock Exchange as of June 30, 2025 was approximately $108,936,270.

*On March 2, 2026, Trinseo PLC received notice from the New York Stock Exchange that it would commence proceedings to delist the Company’s ordinary shares.

Documents Incorporated by Reference

Portions of the registrant’s definitive proxy statement for the 2026 annual general meeting of shareholders to be filed with the Securities and Exchange Commission pursuant to Regulation 14A of the Securities Exchange Act of 1934 are incorporated by reference into Part III of this report.

Cautionary Note Regarding Forward-Looking Statements

This annual report on Form 10-K (“Annual Report”) contains, without limitation, statements concerning plans, objectives, goals, projections, forecasts, strategies, future events or performance, and underlying assumptions and other statements, which are not statements of historical facts. Forward-looking statements may be identified by the use of words like “expect,” “anticipate,” “believe,” “intend,” “forecast,” “estimate,” “see,” “outlook,” “will,” “may,” “might,” “potential,” “likely,” “target,” “plan,” “contemplate,” “seek,” “attempt,” “should,” “could,” “would,” or expressions of similar meaning. Forward-looking statements reflect management’s evaluation of information currently available and are based on our current expectations and assumptions regarding our business, the economy, our current indebtedness and other future conditions. Because forward-looking statements relate to the future, they are subject to inherent uncertainties, risks and changes in circumstances that are difficult to predict.

Specific factors that may cause future results to differ from those expressed by the forward-looking statements, or otherwise impact performance or other predictions of future actions have, in many but not all cases, been identified in connection with specific forward-looking statements. Our actual results may differ materially from those contemplated by the forward-looking statements. They are neither statements of historical fact nor guarantees or assurances of future performance. Important factors that could cause actual results to differ materially from those in the forward-looking statements include economic, business, competitive, market and regulatory conditions and the following:

● our ability to continue as a going concern;

● ongoing discussions with our financial stakeholders;

● the delisting of our ordinary shares from the New York Stock Exchange;

● the stability of our joint ventures;

● changes in global and local tax regulations;

● the limitations of our intellectual property licensing arrangements with Dow;

● our infringement on the intellectual property rights of others;

● cybersecurity incidents, including data breaches or cyber-attacks;

● implementation of our enterprise resource planning system;

● local business risks in the different countries in which we operate;

● fluctuations in currency exchange rates; and

We derive many of our forward-looking statements from our operating budgets and forecasts, which are based upon many detailed assumptions. While we believe that our assumptions are reasonable, we caution that it is very difficult to predict the impact of known factors, and it is impossible for us to anticipate all factors that could affect our actual results. Accordingly, forward-looking statements should not be relied upon as a prediction of actual results. Important factors that could cause actual results to differ materially from our expectations, or cautionary statements, are disclosed under the sections entitled “Risk Factors,” “Management’s Discussion and Analysis of Financial Condition and Results of Operations,” and “Quantitative and Qualitative Disclosures About Market Risk” and in other portions of this Annual Report. All written and oral forward-looking statements attributable to us, or persons acting on our behalf, are expressly qualified in their entirety by the cautionary statements as well as other cautionary statements that are made from time to time in our other public communications. You should evaluate all forward-looking statements made in this Annual Report in the context of these risks and uncertainties.

We caution you that the important factors referenced above may not contain all of the factors that are important to you. Should unknown risks or uncertainties materialize or underlying assumptions prove inaccurate, actual results could differ materially from past results and/or those anticipated, estimated or projected. In addition, we cannot assure you that we will realize the results or developments we expect or anticipate or, even if substantially realized, that they will result in the consequences or affect us or our operations in the way we expect. The forward-looking statements included in this Annual Report are made only as of the date hereof. We undertake no obligation to publicly update or revise any forward-looking statement as a result of new information, future events or otherwise, except as otherwise required by law.

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Page

Part I

Item 1. Business 5

Item 1A. Risk Factors 18

Item 1B. Unresolved Staff Comments 37

Item 1C. Cybersecurity 37

Item 2. Properties 38

Item 3. Legal Proceedings 39

Item 4. Mine Safety Disclosures 39

Part II

Item 6. Reserved 41

Item 7A. Quantitative and Qualitative Disclosures About Market Risk 58

Item 8. Financial Statements and Supplementary Data 60

Item 9A. Controls and Procedures 60

Item 9B. Other Information 61

Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections 62

Part III

Item 10. Directors, Executive Officers and Corporate Governance 62

Item 11. Executive Compensation 62

Item 14. Principal Accounting Fees and Services 63

Part IV

Item 15. Exhibits, Financial Statement Schedules 64

Signatures 71

Index to Consolidated Financial Statements F-1

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Trinseo PLC

Form 10-K Annual Report

For the Fiscal Year Ended December 31, 2025

Unless otherwise indicated or required by context, as used in this Annual Report on Form 10-K (“Annual Report”), the term “Trinseo” refers to Trinseo PLC (NYSE: TSE), a public limited company existing under the laws of Ireland, and not its subsidiaries. The terms “Company,” “we,” “us” and “our” refer to Trinseo and its consolidated subsidiaries, taken as a consolidated entity. All financial data provided in this Annual Report is the financial data of Trinseo PLC, unless otherwise indicated. Prior to the formation of the Company, our business was wholly owned by The Dow Chemical Company (together with other affiliates, “Dow”).

Definitions of capitalized terms not defined herein appear in the notes to our consolidated financial statements. Specifically, refer to Note 16 in the consolidated financial statements for definitions of the Company’s debt facilities.

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PART I

Item 1. Business

Business

The Company

Trinseo PLC is a public limited company existing under the laws of Ireland. Trinseo PLC was merged with our former publicly traded parent entity, Trinseo S.A., with Trinseo PLC as the surviving entity. Prior to the formation of Trinseo S.A., our business was wholly owned by The Dow Chemical Company (together with its affiliates, we refer to as “Dow”). Our predecessor business was sold by Dow in 2010 to investment funds advised or managed by affiliates of Bain Capital Partners, LP (the “Dow Separation”), which fully divested its ownership in the Company in 2016. We have been listed on the New York Stock Exchange (“NYSE”) since June 2014 under the ticker symbol “TSE.” On March 2, 2026, Trinseo PLC received notice from the New York Stock Exchange that it would commence proceedings to delist the Company’s ordinary shares because the Company had fallen below the NYSE continued listing standard requiring companies to maintain an average market capitalization over a 30-trading day period of at least $15 million. The Notice also stated that trading in the Company’s ordinary shares would be suspended effective immediately.

Trinseo PLC is a specialty material solutions provider with a focus on partnering with companies to bring ideas to life in an imaginative, smart, and sustainability-focused manner. Our products are incorporated into a wide range of our customers’ products throughout the world, including products for building and construction, automotive applications, paper and board, appliances, packaging, textile, and consumer electronics, among others. We have long-standing relationships with a diverse base of global customers, many of whom are leaders in their markets and rely on us for formulation, technological differentiation, and compounding expertise to find sustainable solutions for their businesses. Many of our products represent only a small portion of a finished product’s manufacturing costs but provide critical functionality to the finished product and are often specifically developed to customer specifications. Therefore, we seek to regularly develop new and improved products and processes, supported by our intellectual property portfolio and manufacturing know-how, designed to enhance our customers’ product offerings. We believe these products’ traits result in substantial customer loyalty.

We have manufacturing and production operations around the world, which allow us to serve our global customer base. As of December 31, 2025, our production facilities included manufacturing plants and one recycling facility at sites across the globe, including the Company’s joint venture, Americas Styrenics LLC. Additionally, as of December 31, 2025, we operated 11 research and development (“R&D”) facilities globally, including technology and innovation development centers, which we believe are critical to our global presence and innovation capabilities. Our global operations also provide diversity in the end markets for our products.

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Our Strategy

In 2025, we continued to focus our efforts and investments on specialty materials and sustainable solutions product offerings which are less cyclical and offer higher growth and margin potential. We have invested in differentiated and sustainable product offerings serving the applications within our compounding business segments, as well as coatings, adhesives, sealants, and elastomers (“CASE”) applications within the Latex Binders business segment, while closing underperforming or unprofitable product lines to focus on improving cash flow.

We have capabilities to convert post-consumer and post-industrial waste for use in a wide range of high-end applications. We have a polycarbonate (“PC”) dissolution pilot facility in our Terneuzen, the Netherlands plant, a polymethyl methacrylates (“PMMA”) depolymerization plant in Rho, Italy and an acrylonitrile butadiene styrene (“ABS”) dissolution pilot facility in Terneuzen, the Netherlands. These facilities demonstrate our commitment to sustainability and progress toward our sustainable product portfolio goals.

In the face of ongoing challenges affecting the chemical industry and the end markets which we serve, including historically low demand, geopolitical turmoil, and pricing volatility, we have implemented multiple restructuring initiatives including product line shutdowns and workforce reductions which are designed to reduce costs, streamline commercial and operational activities, improve profitability and cash flow generation. We have also taken steps to further reduce our exposure to cyclical markets and strengthen our competitive position through the closure of certain underperforming or uncompetitive plants and product lines and exit from underperforming assets. These steps included the closure of our global styrene manufacturing operations and closure of our virgin polycarbonate manufacturing and polycarbonate plant at our Stade, Germany facility, the closure of our methyl methacrylate (MMA) production operations in Rho, Italy and the related acetone cyanohydrin (ACH) production operations in Porto Marghera, Italy, and polystyrene (“PS”) production operations in Schkopau, Germany. Following these actions, our downstream styrene, polycarbonate, and MMA needs will be purchased from external suppliers. We also have right sized the workforce as a result of the combination of management and supporting functions of our Engineered Materials, Plastics Solutions and Polystyrene businesses.

The Company continues to seek organic growth through expansion into key markets or strategic capital investments targeting technologies and solutions that meet the evolving needs of our customers, and to continue to provide innovative products to our customers who seek our technological and development capabilities to create specialty grades, new and sustainable products, and technologically-differentiated formulations. The Company will continue to focus on growing margins and reducing earnings volatility through such organic investments.

We continue to evaluate strategic alternatives to divest all or a portion of our styrenics businesses, which includes our polystyrene business and our interest in Americas Styrenics LP. In 2024, we announced our interest to sell our share in Americas Styrenics pursuant to an ownership exit provision in the joint venture agreement. The styrenics business separation remains an integral part of our long-term strategy, and we continue to evaluate actions to transform the Company into a higher growth, higher margin and less cyclical specialty and sustainable materials provider.

For more information regarding our strategic highlights see Item 7 – Management’s Discussion and Analysis of Financial Condition and Results of Operations – 2025 Highlights.

Business Segments

The Company operates under four reportable segments: Engineered Materials, Latex Binders, Polymer Solutions, and Americas Styrenics. Our reportable segments reflect the model under which the business is being managed and results are being reviewed by the Chief Executive Officer, who is the Company’s chief operating decision maker.

For additional information regarding business segment results, refer to Item 7 – Management’s Discussion and Analysis of Financial Condition and Results of Operations and Note 23 in the consolidated financial statements.

Engineered Materials Segment

Overview

Our Engineered Materials segment consists of rigid thermoplastic compounds and blends products sold into high growth and high value applications in markets such as consumer electronics, medical and automotive, as well as soft thermoplastic elastomers (“TPEs”) products which are sold into markets such as footwear and automotive. The

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Engineered Materials segment also includes polymethyl methacrylates (“PMMA”) and activated methyl methacrylates (“MMA”) products, which are sold into a variety of applications including automotive, building and construction, medical, consumer electronics, and wellness, among others. During fourth quarter 2025 we ceased MMA production operations in Rho, Italy and ACH production operations in Porto Marghera, Italy. Going forward, all MMA will be purchased from third parties through a combination of long-term supply contracts and spot market purchases.

In 2025, approximately 34% of total Engineered Materials net sales were generated in Europe, approximately 45% were generated in the United States, and approximately 14% were generated in Asia.

Products and End Uses

Products in the Engineered Materials segment are split into rigid compounds, soft plastic compounds, and PMMA resins and sheets. Rigid compounds include PC compounds, ABS compounds, and PC blends, mostly PC/ABS, and support primarily the automotive, consumer electronics and medical markets for equipment housing applications. Thermoplastic elastomer (“TPE”) soft plastic compounds are focused on supporting footwear shoe sole applications, personal care, consumer electronics, and automotive high-end applications such as overmolds, sealings, tubing, and films. PMMA products can be sold as resin compounds or sheets produced through continuous-cast, extrusion, and cell-cast processes. PMMA products are sold primarily into building & construction, automotive, medical and consumer goods applications.

The benefit of Trinseo’s portfolio in our Engineered Materials segment is the high level of customization for high-end applications at selected premium brand owners and clear orientation to sustainable solutions. Our current portfolio includes sustainable solutions, such as high-content post-consumer recycled (“PCR”) polycarbonate and bio-based raw materials. We continue to develop solutions to expand our sustainable offering using PCR ABS, PCR TPE, PCR PMMA and recycled MMA (“R-MMA”) which is chemically recycled. Sustainable products represented 5% of Engineered Materials segment volume in 2025 and are a core growth area.

Compounding. Our compounding products consist of PC/ABS compounds, PC blends, and PC and polypropylene compounds. In 2025, compounding products represented approximately 29% of total segment net sales.

We have a significant position in PC/ABS blends, which combine the heat resistance and impact strength of PC with the easy-to-process qualities and resilience of our ABS. We have also developed compounds containing PCR content in their products.

We sell our compounds products mainly under the EMERGE brand for consumer electronics, and under the CALIBRE brand for medical markets. For the automotive industry, we manufacture PC/ABS blends under the PULSE brand, and we innovate collaboratively with our customers to develop performance solutions to meet industry needs, such as reducing the weight of vehicles or providing products using recycled or sustainable content. We sell our PMMA products primarily under PLEXIGLAS in the United States and ALTUGLAS in Europe and Asia. As a result, we are a key supplier of these products to leading automotive companies in North America and Europe, who tend to specify these products on a per car platform basis, making it difficult to be displaced as a supplier once selected and providing us with relatively stable and predictable cash flows for several years during the production lifecycle. We have an established position in China and are working to further increase our presence in Asia.

We foresee growth in applications of building & construction, consumer goods, and automotive as well as continued initiatives toward light-weighting, paint replacement and digitization. Supported by current macro trends, we believe that we have additional growth opportunities in existing consumer electronics applications, including tablets, notebooks, smart phones and other handheld devices, as well as new voice control systems, home entertainment and delivery equipment. We also foresee growth in medical wearables, home equipment, and drug delivery devices. In serving these markets, we leverage our polymer and compound technologies to meet increasingly stringent performance requirements along with our customers’ aesthetic and color-matching requirements, which are crucial characteristics for the products involved.

We sell our PMMA sheet products primarily under the trade names ALTUGLAS, PLEXIGLAS, ACRYSPA, AVONITE and STUDIO. We foresee growth in wellness applications such as hot tubs and swim spas as well as sanitary applications like bathtubs. More specifically, we are able to effectively serve these markets through our specialized continuous cast sheet production capabilities that allow us to provide large scale PMMA sheet with specific color

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requirements. We have also expanded our product offerings into transportation applications and continue to provide customer solutions in architectural applications such as signage and countertops.

We manufacture our TPE soft plastic compounds principally under the trade names MEGOL, APILON, APIGO, and APINAT. Growth in footwear is supported by bio thermoplastic polyurethane solutions in both luxury and sport premium markets, while automotive growth is orientated to hygienic interiors and both robust and smart surfaces.

Competition and Customers

Our main competitors are Sabic, Covestro, Styrolution, Shanghai Pret Composites Co. Ltd., LG Chem, Lotte Chemical Corporation, and Kingfa for compound technologies, Kraiburg, Celanese, Avient, Hexpol and BASF for TPEs, and Roehm, Plaskolite, Mitsubishi Chemicals and Schweiter Technologies for PMMA resins and sheets.

We compete in the Engineered Materials segment primarily based on our ability to offer differentiated, sustainable and reliable products, high quality customer service, and deep relationships with prioritized customers. We believe that growth in this segment will stem from the continued high demand for engineered and sustainable product solutions serving the consumer electronics, automotive, building & construction, wellness, footwear, medical and lighting application markets. We believe our track record of innovation and our focus on differentiated products enhances our growth prospects in this segment. We also believe that our global organization and facilities are a competitive advantage that allows us to provide customers with consistent grades across different regions and positions us to strategically serve emerging markets.

Seasonality

Due to the steady demand state of a portfolio of applications in many markets, such as consumer electronics, medical devices, footwear, rigid compounds and soft TPE products do not experience significant seasonality. PMMA and compound applications geared towards automotive, building and construction and wellness markets do experience some seasonality.

Latex Binders Segment

Overview

In 2025, approximately 41% of our Latex Binders segment’s sales were generated in Europe, 35% were generated in the United States, and the majority of the remaining net sales were generated in Asia. Additionally, this segment includes the results of our styrene-acrylate latex (“SA latex”) and all-acrylic latex (“AA latex”)production facilities and related infrastructure in the United States, Europe and Asia. The Company’s key area of focus in the Latex Binders segment is to grow our product offerings serving CASE and battery applications, as these offer significantly higher growth and margin potential.

Products and End Uses

SB latex is widely used as a binder for mineral pigments as it allows high coating speeds, improved smoothness, higher gloss level, opacity and water resistance that is valued in the product’s end use in advertising, magazines, and packaging board coatings.

We offer a diverse range of latex binders products to the carpet and artificial turf market for use in residential and commercial applications. We produce SB latex, SA latex, vinylidene chloride, and butadiene-methacrylate latex products for the commercial and niche carpet markets. SB latex is also used in flooring as an adhesive for carpet and artificial turf fibers. We continue to implement new chemistries for paper coating and carpet backing applications.

We also offer a broad range of performance latex binders products, including SB latex, SA latex, and vinylidene chloride latex for CASE applications. Net sales to CASE applications made up approximately 17% of total Latex Binders net sales in 2025.

Competition and Customers

Our principal competitors in our Latex Binders segment include BASF Group and Synthomer plc. In this segment, we compete primarily based on our ability to offer differentiated and reliable products, the quality of our customer

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service, and the length and depth of our relationships. This industry has seen capacity reduction and consolidation which we believe could positively impact our competitive standing.

We believe our Latex Binders segment is able to differentiate itself by offering customers value-added formulations and product development expertise. Our R&D team and Technical Services and Development (“TS&D”) team are able to use our pilot coating facility, paper fabrication and testing labs, carpet technology centers located near carpet producers, and product development and process research centers to assist customers in designing new products and enhancing their manufacturing processes. Many of our major customers rely on our dedicated R&D and TS&D teams to complement their limited in-house resources for formulation and reformulation tests and trials. We believe that this capability allows us to capture new business, strengthen our existing customer relationships and broaden our technological expertise.

Additionally, our global manufacturing footprint is key in allowing us to serve our customers in a cost-effective manner, as latex binders products are costly to ship over long distances due to their high water content. We believe that our global network of service and manufacturing facilities is highly valued by our customers. We seek to capture the value of our R&D and TS&D services and manufacturing capabilities through our pricing strategy.

Seasonality

Polymer Solutions Segment

Overview

Our Polymer Solutions segment consists of a variety of polymers, the majority of which are for building and construction applications. The segment includes our mass acrylonitrile butadiene styrene (“ABS”), styrene-acrylonitrile (“SAN”), and polystyrene businesses, as well as our polycarbonate technology. The Polymer Solutions segment also includes the results of converting post-consumer and post-industrial PMMA, PC, ABS, polystyrene, and other thermoplastic waste for use in a wide range of high-end applications. In 2025, approximately 62% of net sales from our Polymer Solutions segment were generated in Europe, 15% were generated in North America, and the majority of the remaining net sales were generated in Asia.

Products and End Uses

Copolymers. Our copolymers products consist of ABS and SAN. In 2025, copolymers represented approximately 44% of total segment net sales.

We produce mass ABS (“mABS”), a variation of ABS that has lower conversion and capital costs compared to the more common emulsion ABS (“eABS”) process, marketed under our MAGNUM brand. mABS has similar properties to eABS but has greater colorability, thermal stability and lower gloss. mABS products can be manufactured to stricter specifications because they are produced in a continuous process as opposed to the batch process used in eABS. mABS also has environmental benefits such as waste reduction and higher yields. In addition to our own mABS production capacity, we have licensed our proprietary mABS technology to other producers.

Primary end uses for our ABS products include automotive and construction sheet applications. We maintain a significant share of ABS sales into these markets, which we believe is due to the differentiating attributes of our mABS products, our reputation as a knowledgeable and reliable supplier, our broad product mix, and our customer collaboration, including design capabilities.

SAN is composed of styrene and acrylonitrile, which together provide clarity, stiffness, an enhanced ability to be processed, mechanical strength, barrier properties, chemical resistance and heat resistance. Our SAN products are manufactured in Terneuzen, The Netherlands and are used mainly in appliances, consumer goods and construction sheets, due to their low cost, clarity and chemical resistance properties.

Polycarbonate (PC). In December 2024, following the decommissioning of the Stade, Germany polycarbonate plant, the Company no longer manufactures virgin PC and sources its PC needs from external suppliers. However, the

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Company continues to leverage its know-how and IP regarding our proprietary PC technology in the form of licensing agreements, as well as innovation in recycled PC technology.

PC has high levels of clarity, impact resistance and temperature resistance. PC can be used in its neat form (prior to any compounding or blending) for markets such as construction sheets and profiles, medical and lighting. Additionally, PC can be compounded or blended with other polymers, such as ABS, which imparts specific performance attributes tailored to the product’s end use.

Our products for glazing and construction sheets are marketed under the CALIBRE brand name and offer customers a combination of clarity, heat resistance and impact performance.

Polystyrene. We produce polystyrene with a focus on sales to injection molding and thermoforming customers. Our product offerings include a variety of general purpose polystyrenes (“GPPS”) and high impact polystyrene (“HIPS”). HIPS is polystyrene that has been modified with polybutadiene rubber to increase its impact resistant properties. These products provide customers with performance and aesthetics at a relatively low cost across applications, including appliances, packaging, including food packaging and food service disposables, consumer electronics and building and construction materials. We view recycled polystyrene products as important not only for the benefit of the environment but also as a way to better serve our customers by addressing their need for sustainable solutions.

The STYRONTM brand is widely recognized in the global marketplace and we believe our R&D capabilities provide valuable, differentiated solutions for our customers, making us well-positioned to address the sustainability, weight reduction, and safety needs.

In 2025, we closed our PS production operations in Schkopau, Germany with consolidation of remaining PS operations in Tessenderlo, Belgium.

Competition and Customers

Our principal competitors in our Polymer Solutions segment are Covestro AG, Saudi Basic Industries Corporation, INEOS Styrolution, Versalis S.p.A., Shanghai Kumho Sunny Plastics Co., Ltd., LG Chem, Lotte Chemical Corporation, Total S.p.A., Sinopec Corp., Formosa Chemicals & Fibre Corp., and Chi Mei Corporation.

In our Polymer Solutions segment, we compete primarily based on our ability to offer innovative, differentiated, sustainable and reliable products, the quality of our customer service, operational reliability and the length and depth of our customer relationships.

We believe potential growth in the Polymer Solutions segment will be impacted by a number of factors, including consumer preference for lighter-weight and impact-resistant products. Additionally, we believe growth prospects are bolstered by sustainability trends such as electric vehicles and potential government mandates, such as the substitution of lighter-weight plastics for metal in automobiles. Our innovation has contributed to long-standing relationships with customers who are recognized leaders in their respective end markets.

Our customer-centric model focuses on understanding customers’ needs and developing tailored relationships that add value beyond the value of the actual product performance. For durable applications, we focus our efforts on product design engineering initiatives for developing and specifying plastics in the next generation of construction applications and appliances. In non-durable applications, we focus on innovative products that provide clear cost advantages to our customers, serving customers with our cost-advantaged technology and operating excellence. We are also able to offer various sustainable product innovations in our non-durable applications, especially packaging.

Seasonality

Reporting periods impacted by the winter season and unfavorable weather conditions that typically affect the construction and building materials end markets may result in seasonally lower performance in our Polymer Solutions segment. Additionally, sales volumes may fluctuate from quarter-to-quarter as customers may adjust their purchasing patterns based on their expectations of polystyrene price changes caused by underlying raw material cost changes.

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Americas Styrenics Segment

Overview

This segment consists solely of the operations of our 50%-owned joint venture with Chevron Phillips Chemical Company, Americas Styrenics LLC (“Americas Styrenics”), which continues to be a leading producer in North America of both styrene and polystyrene. In 2025, Americas Styrenics supplied 18% of the styrene monomer capacity in North America. We received a total of $12.5 million in cash dividends from Americas Styrenics during 2025.

Products and End Uses

Styrene monomer is a basic building block of plastics and a key input to many of the Company’s products. Styrene monomer is a key raw material for the production of polystyrene, and in 2025 approximately 59% of the styrene monomer produced by Americas Styrenics was consumed in its own production of polystyrene. The remainder of Americas Styrenics’ product is sold as a key raw material to other manufacturers of polystyrene, expandable polystyrene, SB latex, ABS resins, unsaturated polyethylene resins, and styrene-butadiene rubber.

Americas Styrenics also produces GPPS, high heat, high impact resin, and STYRON A-TECHTM polystyrene products. Major applications for these polystyrene products include appliances, food packaging, food service disposables, consumer electronics, and building and construction materials.

Competition and Customers

Americas Styrenics’ principal competitors are INEOS Styrolution, Total S.p.A., and LyondellBasell. In our Americas Styrenics segment, we compete primarily based on our ability to offer reliable products as well as the quality of our customer service and the length and depth of our relationships.

As a leading styrenics producer in North America, this segment is well-positioned to benefit from consolidation dynamics in the styrene and polystyrene industries within the region. Effective operating rates can, from time to time, be impacted by planned and unplanned outages, leading to periods of elevated margins.

Seasonality

Our Relationship with Dow

Following the Dow Separation, we entered into certain long-term agreements with Dow to provide services. We maintain a significant relationship with Dow for certain site services, utilities and certain raw materials purchases. The failure of Dow to perform their obligations, or the termination of these agreements, could adversely affect our operations. See Item 1A—Risk Factors for more information.

We are party to various site services agreements (“SAR SSAs”) for Dow to provide site services to the Company at Dow-owned sites. Conversely, we entered into similar agreements with Dow, where, at Company-owned sites, we provide such services to Dow. These agreements cover general services that are provided at certain facilities co-located with Dow, including utilities, site administration, environmental health and safety, site maintenance and supply chain. These agreements generally have 25-year terms and include options to renew. These agreements may be terminated at any time by agreement of the parties, or, by either party, for cause or under certain circumstances for a material breach. In addition, we may terminate with 12-months’ prior notice to Dow any services identified in any SAR SSA as “terminable.” Highly integrated services, such as electricity and steam, generally cannot be terminated prior to the termination date unless we experience a permanent production unit shut down for which we provide Dow with 15-months’ prior notice, or upon payment of a shutdown fee. Upon expiration or termination, we would be obligated to pay a monthly fee to Dow for a period of 45 to 60 months following the expiration or termination of such SAR SSA. The agreements under which Dow receives services from us may be terminated under the same circumstances and conditions.

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Additionally, we are party to several agreements with Dow for the provision of certain raw materials, including butadiene, and other products, services and other operational arrangements. We are also party to a Capacity Reservation Contract which is an evergreen contract that provides guaranteed access to a certain portion of MMA capacity at a Dow-owned manufacturing facility in North America, which was assumed in connection with our acquisition of the PMMA business from Arkema S.A. (the “PMMA Acquisition”). See Sources and Availability of Raw Materials for more information. Under the Amended and Restated MOD5 Computerized Process Control Software, Licenses and Services Agreement, with Rofan Services (“AR MOD5 Agreement”), Dow provided worldwide process control technology, including hardware, software licenses and support services, and related enterprise resource planning services. We have converted all plant locations from the MOD5 process control technology and do not expect to incur any significant costs going forward.

The Second Amended and Restated Master Outsourcing Services Agreement (“SAR MOSA”) provides for ongoing worldwide services, substantially all of which were no longer provided by Dow. The Company continues to incur certain costs related to the SAR MOSA in 2025, which are expected to decrease in future years based on anticipated site shutdowns and demolition.

For the years ended December 31, 2025, 2024, and 2023, we incurred a total of $37.5 million, $54.5 million, and $140.5 million, respectively, in expenses under the SAR MOSA, AR MOD5 Agreement, and SAR SSAs (including utilities) including $37.5 million, $53.5 million, and $138.5 million, respectively, for both the variable and fixed cost components of the site services agreements and $1.0 million and $2.0 million, for the years ended December 31, 2024 and 2023, respectively, covering all other agreements.

For the years ended December 31, 2025, 2024, and 2023, purchases and other charges from Dow (excluding the SAR MOSA, AR MOD5 Agreement, and SAR SSAs) were approximately $185.3 million, $202.7 million, and $570.5 million, respectively. These purchases and other charges primarily relate to the purchase of raw materials for manufacturing our products. Additionally, for the years ended December 31, 2025, 2024, and 2023, sales to Dow were approximately $11.2 million, $65.4 million, and $95.1 million, respectively principally related to manufacturing of Dow’s products.

Sources and Availability of Raw Materials

The prices of our key raw materials are volatile and can fluctuate significantly over time. While the predominant reason for this volatility is the impact of market imbalances in supply and demand from time to time, energy prices, transportation costs and supplier force majeures have impacted and may continue to impact the volatility of some of our raw materials. The table below shows our key raw materials by reportable segment.

Latex Engineered Polymer Americas

Binders Materials Solutions Styrenics

Acetone X

Benzene X

Bisphenol A X X

Butadiene X X X

Ethylene X

Methyl Methacrylate (MMA) X X

Polycarbonate X X

Styrenic resins X X

Styrene X X X X

We have supply contracts in place to help maintain our supply of raw materials at competitive market prices and seek to implement the most efficient and reliable raw material strategy for each of our segments, including utilizing multiple sources where feasible and maintaining a balance between contracted and spot purchases of raw materials. We also produce raw materials for use by our businesses, and we purchase PCR materials for use in products such as our PC compounds. PMMA products use MMA as the key raw material, which is sourced through supply agreements. During 2025, Dow has supplied us with an aggregate 59% of the MMA used in our PMMA production, both in the United States

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through various supply agreements. In 2025, we obtained approximately 9% of our raw materials from Dow (based on aggregate purchase price).

Following our decision to cease production of styrene, PC, and MMA, these materials are purchased through strategic contracts and/or spot market purchases.

Technology

Our “One Trinseo R&D” operating model refers to our customer-focused R&D and TS&D activities, which are streamlined across our Engineered Materials, Polymer Solutions and Latex Binders business segments. As part of our customer-centric approach, our R&D and TS&D teams interface with our sales and marketing teams, and directly with customers, to determine their product requirements. These teams then consider material scientific factors, as well as industry and market segment trends in order to select, execute and commercialize new sustainable material solutions that are value-enhancing for both our customers and the Company.

Our global network of R&D Centers of Excellence (CoEs) and Technical Centers support our technological and R&D/TS&D capabilities, where our cross-functional teams work and engage with customers on technology and innovation development. We have three R&D CoE locations bringing innovation excellence across the globe in Rheinmünster, Germany, Terneuzen, The Netherlands and Exton Pennsylvania. In addition, our R&D/TS&D efforts are supported by certain “mini-plants” used to make samples of experimental products for testing, which we believe is a critical step in our new product development process. We also operate a plastics research center, which integrates two existing technical support centers and research lab operations in a single location at our Terneuzen R&D CoE location. Further, we operate pilot plants to facilitate new production technology. Finally, our network of global R&D CoEs in Europe and the United States, are responsible for knowledge sharing, synergies and best-practice standardization and talent development across our business segments.

R&D and TS&D costs are included in expenses as incurred. Our R&D and TS&D costs were $63.6 million, $63.5 million, and $57.6 million for the years ended December 31, 2025, 2024, and 2023, respectively.

Sales and Marketing

We have a customer-centric business model that has helped us to develop strong relationships with many customers. Our sales and marketing professionals are primarily located at our facilities or at virtual offices within their respective geographies. We have approximately 180 professionals working in sales and marketing around the world, along with approximately 90 customer service professionals, and we sell our products to customers in approximately80countries. We primarily market our products through our direct sales force. We also leverage various channel management partners, distributors, and agents in the sale of our products. Typically, our direct sales are made by our employees in the regions closest to the given customer.

Intellectual Property

We evaluate on a case-by-case basis how best to utilize patents, trademarks, copyrights, trade secrets and other intellectual property to protect our products and our critical investments in research and development, manufacturing and marketing. We focus on securing and maintaining patents for certain inventions, while maintaining other inventions as trade secrets, derived from our customer-centric business model, to maximize the value of our product portfolio and manufacturing capabilities. Our policy is to seek appropriate protection for significant product and process developments in the major markets where the relevant products are manufactured or sold. Patents may cover products, processes, intermediate products and product uses. Patents extend for varying periods in accordance with the date of patent application filing and the legal life of patents in the various countries. The protection afforded, which may also vary from country to country, depends upon the type of subject matter covered by the patent and the scope of the claims of the patent. The intellectual property that we have created or acquired since our formation covers areas such as material formulations, material process technologies and various end-use industrial applications.

In most industrial countries, patent protection may be available for new substances and formulations, as well as for unique applications and production processes. However, given the geographical scope of our business and our continued growth strategy, there are regions of the world in which we do business or may do business in the future where

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intellectual property protection may be limited and difficult to enforce. We maintain strict information security policies and procedures wherever we do business. These information security policies and procedures include data encryption, controls over the disclosure and safekeeping of confidential information, as well as employee awareness training. Moreover, we monitor our competitors’ products and, if circumstances were to dictate that we do so, we would vigorously challenge the actions of others that conflict with our patents, trademarks and other intellectual property rights.

The technologies we utilize in some of our businesses have been in use for many years (e.g., SB latex, polystyrene, PMMA and ABS) and a number of our patents relating to such technologies have expired or will expire in the future. As patents expire, or are allowed to lapse, the products and processes described and claimed in those patents become generally available for use by the public. We believe that the expiration of any single patent or family of patents that is scheduled to expire would not materially adversely affect our business or financial results. We believe that our trade secrets relating to manufacturing and other processes used in connection with products to which expiring patents relate will continue to provide us with a competitive advantage after the expiration of these patents.

We use trademarks as a means of differentiating our products. We protect our trademarks against infringement where we deem appropriate. We have successfully registered the TRINSEOTM trademark in 130 countries, and also own the Plexiglas®, Altuglas®, Solarkote® and Oroglas® marks as well as other trademarks acquired from Arkema S.A.

Dow has either transferred to us or granted perpetual, royalty-free licenses to us to use Dow’s intellectual property that was used by Dow to operate the acquired business (the “Dow Acquired Business”) prior to the Dow Separation. This intellectual property includes certain processes, compositions and apparatus used in the manufacture of certain of our legacy products. In addition to our license rights to use Dow’s intellectual property related to the Dow Acquired Business, we have obtained licenses to use Dow’s intellectual property to the extent necessary to perform our obligations under the contracts transferred to us in the Dow Separation and to use such intellectual property (other than patents) for products outside of the Dow Acquired Business as it was conducted by Dow prior to the Dow Separation, subject to certain limitations. While we believe our license rights with respect to Dow’s intellectual property are sufficient to allow us to operate our current business, growth opportunities, involving new products may fall outside of our license rights with Dow. Therefore, our ability to develop new products may be impacted by intellectual property rights that have not been licensed to us by Dow. We have the right, with Dow’s cooperation, to directly enforce the patents that are exclusively licensed to us by Dow where infringement is primarily within the scope of our business; but nothing obligates Dow to enforce against third parties the intellectual property rights of Dow that are licensed to us on a non-exclusive basis or where the infringement is primarily outside the scope of our business.

Environmental, Health, Safety and Product Stewardship

Obtaining, producing and distributing many of our products involve the use, storage, transportation and disposal of toxic and hazardous materials. We are subject to extensive, evolving and increasingly stringent environmental and safety laws and regulations, which address, among other things:

● emissions to the air;

● discharges to soils and surface and subsurface waters;

● other releases into the environment;

● climate change impacts;

● process and maintenance of safe conditions in the workplace;

● registration and evaluation of chemicals;

● production, handling, labeling or use of chemicals used or produced by us;

● stewardship of products after manufacture; and

● circular solutions, for polystyrene, PMMA, PC, ABS and other products.

We monitor compliance with applicable local, national, and international environmental, health and safety requirements and maintain policies and procedures to monitor and control environmental, health and safety risks, which

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may in some circumstances exceed the requirements imposed by applicable law. We have an environmental, health and safety organization with a staff of professionals who are responsible for environmental, health, personal safety, process safety, and product regulatory compliance and stewardship, in addition to comprehensive standards and tools. We supplement our programs with our participation in trade associations which monitor developments in legislation impacting our businesses. Additionally, our Supplier Code of Conduct includes our expectations for our suppliers to comply with applicable laws and regulations and encourages them to adhere to the highest principles of environmental responsibility.

We follow the American Chemistry Council Responsible Care® Guiding Principles for our global facilities and products and have received third party certification of our Responsible Care® Management System. Many of our facilities have been certified to ISO 14001 and other ISO management systems. We have a mature corporate environmental, health and safety audit program for our facilities. We conduct regular emergency preparedness and crisis planning and drills, at both the facility and corporate level. We expect that stringent environmental regulations will continue to be imposed on us and our industry in general.

Sustainability and Climate Change

We recognize that climate change has had and will continue to have significant impacts on our environment, particularly as it relates to extreme weather conditions and rising sea levels, and which has prompted regulations limiting, among other things, the emission of greenhouse gases. In the countries in which we operate, particularly in the EU, we are required to comply with increasingly extensive regulations to address climate change impacts and resource conservation requirements. We also monitor legislative actions and their potential impacts on the end markets we serve.

We track and publicly report our greenhouse gas emissions, water usage, waste, and energy consumptions and our facilities continue to target reductions and improvements in these areas. Our annual Sustainability and Corporate Social Responsibility Report (the “Sustainability Report”), which is available on our website, provides our most recent sustainability highlights for our products, performance and operations. The report highlights sustainability goals and other initiatives to improve our sustainability performance.

Sustainability is a key focus area of our long-term strategy. As part of this strategy, we have successfully opened a PMMA depolymerization pilot facility in Rho, Italy, which uses a continuous process to produce high-purity regenerated MMA from pre- and post-consumer acrylic solutions. This technology returns material to its monomer form and allows additives and contaminants to be removed, which previously could not be done through mechanical recycling. We also operate a polycarbonate dissolution pilot facility and an ABS dissolution technology recycling pilot plant in our Terneuzen, the Netherlands site. These sites, along with our Heathland B.V. recycling operations, represent important steps in realizing our sustainability goals.

We continue to publish an annual Sustainability & Corporate Responsibility Report with reference to the Global Reporting Initiative (“GRI”) framework, the Sustainability Accounting Standards Board (“SASB”) framework and strive to set a high standard for safety and Employee Health & Safety (“EH&S”) goals. We expect the costs of administering our sustainability program and complying with evolving disclosure regulations to increase as we continue to focus and improve our sustainability initiatives and reporting.

Environmental Remediation

Environmental laws and regulations require mitigation or remediation of the effects of the disposal or release of chemical substances. Under some of these regulations, as the current owner or operator of a property, we could be held liable for the costs of removal or remediation of hazardous substances on or under the property, without regard to whether we knew of or caused the contamination, and regardless of whether the practices that resulted in the contamination were permitted at the time they occurred. Many of our production sites have an extended history of industrial use, and it is impossible to predict precisely what effect these laws and regulations will have on us in the future. In March 2023, we reported an accidental release of acrylic latex emulsion which occurred at our Bristol, Pennsylvania site, which a portion of this material ultimately flowed into a local waterway, and certain environmental claims related to this release, some of which are still ongoing. In the past, soil and groundwater contamination occurred at some of the sites and might occur or be discovered at other sites. Subject to certain limitations, Dow is obligated to indemnify and hold us harmless with respect to releases of hazardous material that existed at our sites prior to the Dow Separation, however, the period for new claims at these sites has expired. Any active remedial projects on our properties

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which were part of the Dow Separation are being performed by Dow pursuant to its indemnification obligations. We cannot be certain that Dow will continue to fully honor their existing indemnity obligations or that the indemnity will be sufficient to satisfy all claims that we may incur. Sites acquired after the Dow Separation are subject to different limitations or may not be covered by an indemnity. We conduct comprehensive environmental due diligence for potential acquisitions to mitigate the risk of assuming obligations to conduct material levels of environmental remediation. For a more detailed description of the risks related to environmental remediation, see Item 1A—Risk Factors.

Board Oversight

The Environmental, Health, Safety, Sustainability and Public Policy Committee (the “EHSS&PP Committee”) of the Company’s Board of Directors assists the Board with oversight of Company programs, policies and initiatives that support the environment, health and safety, sustainability, corporate social responsibility and climate change. The EHSS&PP Committee is responsible for supporting alignment between the Company and the Board on the Company’s sustainability, social, and public policy goals; guiding the Company and overseeing management of risks arising from our sustainability programs, policies, partnerships, activities and goals; reviewing external public policy/governmental affairs issues and trends and recommending Company response to these issues. The EHSS&PP Committee also reviews the Company’s annual Sustainability Report for Board approval and publication on the Company’s website.

Government Regulation

In addition to environmental, health, and safety laws and regulations, our operations subject us to numerous federal, state, and local laws and regulations in the countries in which we operate. International trade laws and trade agreements, tariffs, and export and customs controls can limit the countries in which we can do business or add significant cost to the import or export of our products or raw materials. Changes or violations of these regulations could impact the costs of our goods or cause delay in shipments. Our products are also used in a variety of end-uses that have specific regulatory or consumer safety requirements such as those relating to food packaging or medical devices. Changes in these requirements could result in increased compliance costs, product recalls, or fines, which could prevent or inhibit the development and sale of our products. These and other laws and regulations impact the manner in which the Company conducts its business, and changes in legislation or government regulations can affect the Company’s global operations, both favorably and unfavorably. For a more detailed description of the various laws and regulations that affect the Company’s business, see Item 1A—Risk Factors.

Security

We recognize the importance of security and safety to our employees and the community. Physical security measures have been combined with process safety measures (including the use of technology) and emergency response preparedness into integrated security plans. We have conducted information security assessments at our operating facilities worldwide and, on an ongoing basis, we work to implement appropriate measures to protect these facilities from physical and cyber-attacks. Effort and resources in assessing security requirements at our manufacturing facilities will continue, as required by U.S. Department of Homeland Security and other requirements.

The Company has implemented information security solutions, resources, policies, programs, and monitoring alerts to respond to potential information security events and to maintain compliance with the increasing amount of data privacy laws and regulation. Our Board of Directors provides oversight of security risks, measures and incidents, with input from members of management and our information security team. For a more information on the Company’s cyber risk management program, see Item 1C—Cybersecurity.

Human Capital Resources and Objectives

As of December 31, 2025, we had approximately 2,800 employees worldwide, with the majority (approximately 55%) located in the EMEA region (Europe, Middle East and Africa), approximately 30% in the Americas, and the remainder in Asia Pacific. Approximately 97% of our workforce is full-time.

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Nearly 70% of our personnel are located at the various manufacturing sites, research and development, and technology centers. The remaining employees are located at operating centers, virtual locations or geographically dispersed marketing and sales locations. Our facilities in Midland, Michigan, Bristol, Pennsylvania, as well as Louisville and Florence, Kentucky have union representation, while employees at certain of our other locations are represented by work councils. We believe we maintain good relations with our personnel and various labor organizations. There have been no labor strikes or work stoppages in these locations in recent history.

People Strategy

We strive to retain a talented and inclusive workforce and understand that our success requires ongoing investment in our employees. Our approach to attracting and retaining talent is our commitment to our core values of Responsible Care®, Innovation, Respect & Integrity, Accountability & Value Creation, and Commitment to Customers. As applied to our employees, these values prioritize health and safety, accountability and rewards for achievement, and treatment of all persons in our organization with respect, honesty, and dignity.

Our core values are reflected in the goals of our “People Strategy,” which is designed to support employees through Organizational Development, Talent Management, Equity & Inclusion and Recognition & Rewards. Organizational Development focuses on the design of organization models to achieve our business strategies, assess employee engagement, shape our culture and facilitate open communication. Talent Management measures our ability to attract and select the right talent for the right roles, onboard new employees to improve integration, build critical capabilities, and develop leaders of the future, with a culture of collaboration among high-performing and diverse teams. Equity & Inclusion challenges us to create and maintain an environment that welcomes a broad range of diverse talent and facilitates and fosters a culture of inclusion. Recognition & Rewards means our efforts to manage, measure, and pay for performance; differentiate and recognize job growth with base salary increases, promotions, new assignments, annual performance awards and recognition of outstanding contributions from employees.

Employee Health & Safety

Focus on the safety of our employees is a critical aspect of our operations. We strive towards achieving zero injuries, spills, or process safety incidents in our facilities every year. Our EH&S management system promotes a culture of rigorous investigation, corrective action, and continuous improvement applied over many years and has delivered a world-class set of internal safety policies, processes, and procedures. This system is designed to meet our objectives to continually reduce safety and environmental incidents and risks, maintain full regulatory compliance, satisfy stakeholder expectations, optimize resources, and continuously improve. We have developed a set of leading indicators and training programs to help highlight and drive improvement in Operational Safety, Process Safety, and Product Safety across the company, with effectiveness assessed on a regular basis and modified as needed to drive improvement.

Equity & Inclusion

We are committed to maintaining an inclusive workforce that offers a broad range of perspectives, backgrounds and experience, and creating an environment in which all Trinseo employees have an equal opportunity to reach their potential and contribute fully to the success of the Company. Trinseo provides an equal employment opportunity, with a policy to recruit, hire, develop, and promote qualified applicants or employees without regard to race, color, religion, sex, pregnancy, gender identity, sexual orientation, veteran status, national origin, age, disability, or genetic information. We believe our commitment to equity and inclusion, and attracting the best candidates, is reflected in our Board and executive leadership team. Fifty-five percent of our Board and thirty-three percent of our executive leadership team are women, and three of our Board members self-identify as a member of an underrepresented minority group. Our executive leadership team also represents broad citizenship and geographic diversity.

Talent Management and Employee Development

We provide opportunities for career development through a combination of training, coaching, and on-the-job experiences. We believe this approach to development provides our employees with the right balance of learning options. Further, we believe that early investment in our employees ensures that our future leaders have the skills they will need to be successful within a complex and ever-changing business environment. Our annual succession planning process identifies successors for some of our most critical roles and recommends tangible developmental actions for incorporation into their long-term personal development plans. We also utilize a goal setting scorecard that enables

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employees to document and align their goals within a leadership team and across functions, which goals are set against annual Company priorities. Employees are evaluated on their performance versus individual goals and on the Company’s performance versus corporate goals (which includes financial and safety metrics). Part of the annual performance review process includes personal assessment goals which are tracked and reviewed throughout the year.

Compensation Policies

Our process for determination of remuneration consists of two main components: base pay and an annual variable program, and we are committed to ensuring equitable compensation among our employees. As stated above, equal opportunity and diversity are important at Trinseo. We conduct internal reviews to assess fair treatment to determine if our pay practices are being implemented appropriately in all jurisdictions where we operate. In the United States, we also conduct internal reviews with new hires as well as an annual exam to determine the impact of ethnicity on pay decisions.

Available Information

Our annual reports on Form 10-K, quarterly reports on Form 10-Q and current reports on Form 8-K, and amendments to those reports filed or furnished pursuant to Section 13(a) or 15(d) of the Securities Exchange Act of 1934, are available free of charge through the Investor Relations section of our website, www.trinseo.com, as soon as reasonably practicable after the reports are electronically filed or furnished with the U.S. Securities and Exchange Commission (“SEC”). Copies of our board committee charters, code of conduct, corporate governance guidelines and other corporate governance information are also available on our website. See Part III–Item 10–Code of Ethics. We provide this website and the information contained in or connected to it for informational purposes only. This information is not included in, or incorporated by reference to, this Annual Report.

Item 1A. Risk Factors

SUMMARY OF RISK FACTORS

The following is a summary of the principal risks that could adversely affect our business, operations and financial results. For a more complete discussion of the material risks facing our business, please see below. As noted under “Forward-Looking Statements” above, these factors could affect our future results and cause actual results to differ materially from those expressed in our forward-looking statements. Investors and other readers are urged to consider all of these risks, uncertainties and other factors carefully in evaluating our business.

● Risks associated with our ability to continue as a going concern.

● Deterioration of our credit profile limiting our access to commercial credit.

● Risks related to our current and future level of indebtedness.

● Our ability to successfully innovate and develop new products.

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● Operation of our joint venture with our joint venture partners.

● Risks related to strategic acquisitions or dispositions of assets.

● The impact of global trade conflicts and the imposition of tariffs.

● Our ability to comply with environmental, health and safety laws.

● We face competitive risks related to excess supply capacity.

● Negative impacts of fluctuations in currency exchange rates.

Risks Related to Our Ability to Continue as a Going Concern

We have identified conditions and events that raise substantial doubt about our ability to continue as a going concern.Doubts regarding our ability to continue as a going concern could materially adversely affect our business, results of operations and financial condition, and share price.

We have identified certain conditions or events, which, considered in the aggregate, could raise substantial doubt about our ability to continue as a going concern, including our continued compliance with certain financial covenants contained in our debt agreements and the current maturities of our existing debt facilities, our continued liquidity and anticipated capital requirements, including service of our debt, the significant uncertainty created by the current macroeconomic and geopolitical operating environment, including global trade conflicts and the imposition of tariffs,

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inflation, geopolitical tensions or conflicts (such as the Russia-Ukraine war and military conflict in Iran), and weak demand in many of our end markets.

Based on our substantial debt balance, the uncertainty surrounding compliance with our debt covenants, our ability to obtain waivers or amendments, or our ability to restructure our indebtedness, including through an in-court or out-of-court process, we have determined that there is substantial doubt regarding our ability to continue as a going concern for a period of twelve months from the issuance of the accompanying audited consolidated financial statements.

Doubts regarding our ability to continue as a going concern could result in the loss of confidence by customers, vendors, suppliers, employees and others, which in turn could materially adversely affect our business, results of operations and financial condition. Concerns about our financial condition could adversely impact the payment terms we can obtain from some of our vendors and suppliers. As a result of such actions, our suppliers may stop extending us trade credit, demand cash in advance payments, refuse to ship materials to us and otherwise threaten to terminate their relationship with us, among other remedies.

Furthermore, we depend on our ability to retain our key employees at all levels of our business and on our ability to attract new qualified personnel. If we are unable to retain our key employees and we do not succeed in attracting new qualified personnel as a result of the uncertainty regarding our ability to continue as a going concern, our business and results of operations could suffer.

Doubts regarding our ability to continue as a going concern may also adversely impact our customers’ perceptions of our business and our continued viability, which in turn could further negatively impact our revenues. Further declines in our revenues as a result of these perceptions or otherwise may have a material adverse impact on our cash flows, results of operations and financial condition, which may require us to curtail or cease operations.

We caution that trading in our ordinary shares may be highly speculative and pose a substantial risk of loss. Trading prices for our ordinary shares may bear little or no relationship to their actual value.

See “Potential Restructuring of Our Indebtedness” in Note 1, “Going Concern” in Note 2, and “Compliance with Debt Covenants” in Note 16 to our consolidated financial statements and Item 7—Management’s Discussion and Analysis of Financial Conditions and Results of Operations— Capital Resources, Indebtedness and Liquidity, for additional information.

Unexpected payment obligations or unanticipated liabilities may create liquidity challenges and further challenge our ability to continue as a going concern.

Unexpected payment obligations or unanticipated liabilities, including, without limitation, matters arising from ongoing litigation or arbitration, governmental investigations, regulatory enforcement actions, fines or penalties, adverse tax assessments, contractual indemnities, product liability or warranty claims, intellectual property disputes, environmental remediation obligations, data privacy or cybersecurity incidents, employment-related claims, and other contingent or off-balance sheet obligations, may result in adverse outcomes, monetary awards, settlements, fines, penalties, remediation costs, or other charges against the Company, representing a condition that may raise substantial doubt about our ability to continue as a going concern, and we may not have sufficient liquidity or capital resources to meet our current or future obligations as a result. If we become subject to future unanticipated large liability claims, obligations, or losses, unexpected risks may arise and previously known risks may materialize in a manner not consistent with our preliminary risk analysis, which may adversely affect our reputation, share price, liquidity, results of operations, cash flows, and overall financial condition.

We may be unsuccessful in discussions with our financial stakeholders, including for the potential restructuring of our indebtedness or may be unable to obtain necessary waivers or amendments.

Due to the uncertainty concerning our ability to service our substantial indebtedness and meet the related financial covenant requirements, we are engaged in ongoing discussions with our financial stakeholders to review potential alternatives regarding our capital structure, including refinancings, exchange offers, consent solicitations, the issuance of new indebtedness, amendments to the terms of our existing indebtedness and/or other transactions. We have also

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engaged outside advisors with respect to these alternatives and have recently appointed two new board members with significant experience in debt restructuring and strategic transactions.

Among these alternatives is a restructuring that would, on a consensual basis, seek to modify the terms of substantially all of our outstanding indebtedness, including through an in-court or out-of-court restructuring process. We may offer to exchange the indebtedness under our 2028 Refinance Term Loans, 2028 Term Loan B, or 2029 Refinance Senior Notes for new debt and/or equity securities. In conjunction with any such transactions, we may seek consents to amend the documents governing our indebtedness to amend or eliminate certain covenants or collateral provisions. Because the terms of any such transactions will be subject to negotiations with the holders of our indebtedness, they may differ materially from those described above and are, to a large extent, outside of our control. There can be no assurance that we will decide to pursue, or be able to complete any such transactions, and there can be no assurance that any such measures will be successful.

In February 2026 we entered into an amendment to the credit agreement governing our 2028 Term Loan B (the “Senior Credit Facility”), which extended the grace period for payment of interest due before March 1, 2026 until March 19, 2026, and elected to utilize the contractually-available grace periods for payment of interest on both the 2028 Term Loan B and our 2029 Refinance Senior Notes. These grace periods will both expire on March 19, 2026. A failure to make the interest payment owed under either the Senior Credit Facility or the 2029 Refinance Senior Notes indenture (the “2L Note Indenture”) at the end of the contractually-available grace period would result in an event of default under such facilities and a cross-default under the other facility, and also result in a cross-default under our 2028 Refinance Credit Facility, our Opco Super-Priority Revolver, and our accounts receivable securitization facility.

We expect to seek amendments to our Senior Credit Facility, our 2028 Refinance Credit Facility, our OpCo Super-Priority Revolver and our accounts receivable securitization facility to waive certain acceleration and collateral enforcement rights under such facilities following certain events of default or cross-defaults. and to remove certain covenants and other provisions. There can be no assurance that any such additional waivers or amendments would be available on acceptable terms or at all.

If we seek but are unable to obtain necessary consents, waivers or amendments from our lenders, and a default or cross-default occurs under our indebtedness and our debt is accelerated, there can be no assurance that we would be able to obtain replacement financing arrangements or successfully restructure our indebtedness. Our failure to complete any of these potential alternatives, including obtaining waivers or amendments to prevent the acceleration of our indebtedness, to prevent the exercise of remedies against the collateral securing such indebtedness, such as the possession and disposal of pledged assets, or our failure to restructure our indebtedness through an in-court or out-of-court process, could have a material adverse impact on our liquidity and financial condition.

Deterioration of our credit profile could limit our access to commercial credit.

We currently maintain credit ratings near the lower end of the rating scale, which limits our financial flexibility and affects the cost and availability of our capital. Operating at these rating levels may reduce the number of lenders and counterparties willing to provide credit on acceptable terms and require us to provide cash-in-advance payments to raw material suppliers and other vendors. Any downgrade from our current ratings, any further deterioration in our credit profile, doubts about our ability to meet our payment obligations or covenants under our indebtedness, or doubts about our ability continue as a going concern, could increase our borrowing costs, reduce our credit capacity, restrict our access to commercial credit markets, or trigger additional collateral, covenant, or liquidity requirements under certain agreements. These developments could adversely affect our liquidity, financial condition, and results of operations.

Risks Related to Delisting of our Ordinary Shares

We have received notice of delisting procedures from the New York Stock Exchange (“NYSE”) and trading in our shares has been suspended, and trading may continue to be restricted with no trading market readily available.

On March 2, 2026, we received written notice (the “Notice”) from the New York Stock Exchange (the “NYSE”) that they determined to commence proceedings to delist the Company’s ordinary shares and will file a Form 25 with the SEC to delist the Company’s ordinary shares from the NYSE upon completion of applicable procedures. The delisting will be effective 10 days after the filing of the Form 25. As stated in the Notice, the NYSE reached its decision to delist the Company’s securities pursuant to Section 802.01B of the NYSE Listed Company Manual because the Company had

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fallen below the NYSE continued listing standard requiring listed companies to maintain an average market capitalization over a 30-trading day period of at least $15.0 million.

Upon suspension of trading and delisting of the Company’s ordinary shares from the NYSE, transfers of ordinary shares will be subject to Irish stamp duty at a rate of 1% of the higher of the purchase price or the market value of the shares, unless an exemption or relief is available to the purchaser. The Company’s clearing and settlement agent, Depository Trust Company, has notified the Company that as a result of the application of Irish stamp duty it will cease clearing or settling trades in our ordinary shares. Our shareholders may not be able to continue to trade in our ordinary shares without transferring their shares to another clearing and settlement agent, or into a registered position directly with the Company’s transfer agent. The Company can provide no assurance that its ordinary shares will continue trading on any market, without transfer of shares to another settlement agent or direct registration with its transfer agent. However, the Company can provide no assurance that its ordinary shares will trade or be quoted on the OTC Pink Limited Market or any other market, or, if such trading or quotation does commence, that such trading will continue, whether broker-dealers will continue to provide public quotes of its ordinary shares on this market, or whether the trading volume of its ordinary shares will be sufficient to provide for an efficient trading market for existing and potential holders of its ordinary shares. Shareholders are advised to consult with their own tax and legal counsel regarding the potential issues related to trading the ordinary shares following the suspension of trading and delisting from the NYSE. Shareholders are advised to consult with their brokers to inquire about the process to register their ordinary shares into a direct position in their name with the Company’s transfer agent, Computershare Trust Company, N.A., if they wish to sell their shares in the Company

Delisting also could limit our strategic or financial alternatives and have other negative results, including the potential loss of employee confidence or the loss of institutional investors. Similarly, customers, vendors, landlords, banks or other third parties may be less willing to transact business with us if they believe our future is uncertain, any of which could adversely impact our business, financial performance, financial position or future prospects.

Risks Related to Our Indebtedness

Our current and future level of indebtedness of our subsidiaries could adversely affect our financial condition.

Our current level of indebtedness, as well as future borrowings or other indebtedness, could have significant consequences for our business, including but not limited to:

● substantially increasing our borrowing costs;

The terms of our debt contain significant restrictions on the incurrence of additional indebtedness and pledge of existing or future assets. These restrictions are subject to certain qualifications and exceptions which could allow us to incur additional indebtedness. If new debt is added to our subsidiaries’ current debt levels, the risks related to indebtedness that we now face could intensify.

In addition, the majority of our current indebtedness is secured by virtually all of our assets, which may make it more difficult to secure additional borrowings at reasonable costs. If we default or declare bankruptcy, after these

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obligations are met, there may not be sufficient funds or assets to satisfy our subordinate interests, including those of our shareholders.

For more information regarding our indebtedness, see Item 7—Management’s Discussion and Analysis of Financial Conditions and Results of Operations— Capital Resources, Indebtedness and Liquidity.

The terms of our subsidiaries’ indebtedness may restrict our current and future operations, particularly our ability to respond to change or to take certain actions.

Our credit, debt and refinance agreements contain covenants imposing certain restrictions on our subsidiaries’ businesses. These restrictions may affect our ability to operate our business and may limit our ability to take advantage of business opportunities. These agreements restrict, among other things, our subsidiaries’ ability to:

● sell or assign assets;

● incur additional indebtedness;

● pay dividends to Trinseo PLC;

● make investments or acquisitions;

● incur liens;

● repurchase or redeem capital shares;

● engage in mergers or consolidations;

● materially alter the business they conduct;

● engage in transactions with affiliates; and

● consolidate, merge or transfer all or substantially all of their assets.

We are required to meet a minimum liquidity test under our 2028 Refinance Credit Agreement, our OpCo Super-Priority Revolver and our accounts receivable securitization facility. The OpCo Super-Priority Revolver also contains a revised springing covenant and an anti-cash hoarding covenant. The ability of our subsidiaries to comply with the covenants, financial ratios and tests contained in the Credit Agreement, the 2028 Refinance Credit Agreement, the OpCo Super-Priority Revolver and the Indenture, to pay interest on indebtedness, fund working capital, and make anticipated capital expenditures depends on our future performance, which is subject to general economic conditions and other factors, some of which are beyond our control. There can be no assurance that our business will generate sufficient cash flow from operations in an amount sufficient to enable us to service our indebtedness, or that sufficient borrowings will be available under our Senior Credit Facility, OpCo Super-Priority Revolver, 2028 Refinance Credit Facility or our accounts receivable securitization facility to fund future liquidity needs. Furthermore, if we need additional capital for general corporate purposes or to execute on an expansion strategy, there can be no assurance that this capital will be available on satisfactory terms or at all.

A failure to service or repay amounts owed under the Senior Credit Facility, 2028 Refinance Credit Facility, OpCo Super-Priority Revolver or 2L Note Indenture when due, or at the end of any applicable grace period, would result in a default. In addition, a breach of any of the covenants in the Credit Agreement, 2028 Refinance Credit Agreement, OpCo Super-Priority Revolver, Indenture or accounts receivable securitization facility, or our inability to comply with the required financial ratios, tests or limits could result in a default. A default under one of our subsidiaries’ debt agreements may trigger a cross-default under some or all of our other debt agreements. If a default occurs, lenders may refuse to lend us additional funds or terminate existing commitments, lenders or noteholders could declare all of the debt and any accrued interest and fees immediately due and payable and demand immediate repayment, or certain lenders could exercise remedies against the collateral securing their debt agreements, including but not limited to rights to take possession and dispose of certain of our assets. For more information regarding our indebtedness, please see Item 7—Management’s Discussion and Analysis of Financial Conditions and Results of Operations— Capital Resources, Indebtedness and Liquidity.

Risks Related to Our Operations

We are subject to risks associated with our strategy to transform to a specialty materials and sustainable solutions provider.

We have taken steps toward executing on our strategy to transform the Company to a specialty materials and sustainable solutions provider, including the PMMA Acquisition, the acquisition of Aristech Surfaces LLC, the sale of

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our synthetic rubber business, and the sale of our proprietary polycarbonate manufacturing assets in Stade, Germany. We plan to continue to prioritize investments in higher growth, higher margin and lower earnings volatility areas such as Engineered Materials and CASE applications, products containing recycled materials, and to deemphasize the more volatile, lower growth assets in our portfolio.

The implementation of our transformation strategy has resulted in, and may continue to result in, changes to our business, operations, capital allocation, operational and organizational structure, increased demands on management, and could result in short-term and one-time costs, including higher than expected restructuring costs, loss of revenue, and other negative impacts on our business. We cannot guarantee that the execution of this strategy, including the steps taken to date, will lead to higher growth, higher margins and lower earnings volatility. We also cannot be certain that we will be successful in identifying investments in assets we believe best fit our portfolio transformation, whether such opportunities will be available at a price and at terms acceptable to us, or at all, or whether we will face difficulties due to timing or funding availability. Implementation of this transformation may take longer than anticipated, and once implemented, we may not realize, in full or in part, the anticipated benefits or such benefits may be realized more slowly than anticipated. The failure to realize benefits, which may be due to our inability to execute, delays in implementation, global or local economic conditions, accessibility to capital markets, inflation, high interest rates, competition, and the other risks described herein, could have a material adverse effect on our business, prospects, financial condition, results of operations, cash flows, as well as the trading price of our securities.

We may be unable to achieve cost savings and other benefits from our restructuring activities and cost reduction initiatives.

We have announced several restructuring programs designed to reduce costs, streamline commercial and operational activities, improve profitability, preserve cash flow and reduce exposure to cyclical markets. These plans included workforce reductions and the elimination and consolidation of certain executive positions to streamline the Company’s internal general & administrative network. As a result of these closures, we no longer produce certain products and instead will purchase from external suppliers.

We believe these actions will reduce production risk and exposure to cyclical markets, reduce ongoing capital expenditures and future turnaround costs. We believe these actions will increase our profitability and cash generation until market conditions improve, while allowing us to continue focusing on transformation projects such as recycling and material substitution innovations, which offer growth potential even in the current market environment.

Our efforts to achieve these improvements and efficiencies may not be successful or generate expected cost savings, and we may incur greater costs than currently anticipated to complete these initiatives, which could have an adverse impact on our financial condition or results of operations. We cannot guarantee that these initiatives will successfully generate the expected cost savings or will not require additional expenditures beyond our initial estimates. The actual timing and costs of this asset restructuring may differ from our expectations and estimates, and such differences may be material.

Volatility in the cost of raw materials, disruption in the supply of raw materials, may adversely affect our financial condition and results of operations or cause our financial results to differ materially from our forecasts.

Our results of operations can be directly affected, positively and negatively, by volatility in the cost of our raw materials, which are subject to global supply and demand and other factors beyond our control. Our principal raw materials (butadiene, MMA, and styrene) together represent approximately 44% of our total cost of goods sold. Crude oil prices also impact our raw material and energy costs. Generally, higher crude oil prices lead to higher costs of natural gas and raw materials, although some raw materials are impacted less than others. Volatility in the cost of energy or raw materials makes it more challenging to manage pricing and pass the increases on to our customers in a timely manner. We believe that rapid changes in pricing have affected, and can continue to affect, the volume our customers consume. As a result, our gross profit and margins could also be adversely affected and our financial results may differ materially from our forecasts.

We have supply agreements with Dow and other suppliers for certain raw materials critical to our business. As these supply agreements expire, we may be unable to renegotiate or renew these contracts or obtain new long-term supply agreements on terms comparable to us, or at all, which may significantly impact our operations. See Item 1—Business— Sources and Availability of Raw Materials.

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If the availability of any of our principal raw materials is limited, we may be unable to produce some of our products in the quantities demanded by our customers, which could have an adverse effect on plant utilization and our sales of products requiring such raw materials. Suppliers may have temporary limitations preventing them from meeting our requirements, and we may not be able to obtain substitute alternative suppliers in a timely manner.

Increased energy costs, shipping costs and supply constraints, including as a result of ongoing global conflicts, could adversely impact our results of operations.

We use natural gas and electricity to operate our facilities and generate heat and steam for our various manufacturing processes, and these operations can be directly affected by volatility in the cost and availability of energy, which is often subject to factors outside of our control. The war between Russia and Ukraine continues to affect global energy markets, particularly in Europe, contributing to elevated volatility and higher prices for natural gas and other energy supplies. Reductions in Russian natural gas deliveries to Europe have resulted in supply constraints which are expected to persist. Prolonged or worsening natural gas shortages could lead to additional price increases, energy-supply rationing, or temporary reductions or shutdowns of our European manufacturing operations, any of which could materially and adversely affect our business or results of operations. In the past we have entered into certain commodity swap agreements to protect against fluctuations in energy prices, including natural gas, some of which have generated losses when prices stabilized. We may continue to enter into commodity swaps, forward contracts, or options from time to time. The outcome of our hedges against energy price volatility could adversely impact our results of operations.

Global conflicts and geopolitical instability may adversely affect our regional and global shipping networks, increase transportation and logistics costs, and delay shipments of our products or the raw materials on which we rely. The recent escalation of military conflict involving Iran, including retaliatory strikes across the Middle East and disruptions to commercial shipping lanes, has further strained transit routes through the Red Sea and surrounding regions. These conditions have contributed to longer transit times, elevated freight and insurance costs, and increased uncertainty for vessel availability. A broader or prolonged regional conflict could amplify these impacts, potentially disrupting key supply chains, increasing our operating costs, and materially and adversely affecting our results of operations.

Chemical manufacturing is inherently hazardous and production at our manufacturing facilities could be disrupted for a variety of reasons. Disruptions could expose us to significant losses or liabilities.

There are hazards and risks of disruption inherent in chemical manufacturing and the related storage and transportation of raw materials, products and wastes which exist in our operations and the operations of other occupants with whom we share manufacturing sites. These potential risks of disruption include, but are not necessarily limited to:

● pipeline and storage tank leaks and ruptures;

● explosions and fires;

● terrorist attacks;

● cyber-attacks to our operations or those of critical third parties;

● failures or delays in properly implementing new technologies and processes;

● exposure to toxic chemicals.

These hazards could expose employees, customers, the community and others to toxic chemicals and other hazards, contaminate the environment, damage property, result in personal injury or death, lead to an interruption or suspension of operations, damage our reputation and adversely affect the productivity and profitability of a particular manufacturing facility or us as a whole, and result in the need for remediation, governmental enforcement, regulatory shutdowns, the imposition of government fines and penalties, and claims brought by governmental entities or third parties. Legal claims and regulatory actions could subject us to both civil and criminal penalties, which could affect our product sales, reputation and profitability. Liabilities associated with the investigation and cleanup of hazardous substances, as well as personal injury, property damage or environmental damages arising from the release of, or

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exposure to, such hazardous substances, may be imposed in many situations without regard to violations of laws or regulations or other fault. These liabilities may be material and can be difficult to identify or quantify.

We are dependent upon the continued safe and reliable operation of our production facilities to minimize risks associated with our manufacturing processes, but we cannot eliminate the risk of accidental contamination, discharge or injury resulting from these materials. We have been in the past, and may be in the future, subject to claims relating to exposure to hazardous materials, and have had, from time to time in the past, incidents that have temporarily shut down or otherwise disrupted our manufacturing, causing production delays and resulting in liability for workplace injuries, environmental remediation, regulatory penalties or other claims. Systems in place to manage environmental, health and safety compliance, and our emergency response and crisis management plans may not address or foresee all potential risks or causes of disruption, or sufficiently address the impacts of such incidents on our employees, customers or the communities in which our plants reside. We cannot assure you that we will not experience these types of incidents in the future or that these incidents will not result in production delays or otherwise have a material adverse effect on our business, reputation, financial condition or results of operations.

If disruptions occur, alternative facilities with sufficient capacity or capabilities may not be available, may cost substantially more or may take a significant time to start production. Each of these scenarios could negatively affect our business and financial performance. If one of our key manufacturing facilities is unable to produce our products for an extended period of time, our sales may be reduced by the shortfall caused by the disruption and we may not be able to meet our customers’ needs, which could cause them to seek other suppliers. Furthermore, to the extent a production disruption occurs at a manufacturing facility that has been operating at or near full capacity, the resulting shortage of our product could be particularly harmful because production at the manufacturing facility may not be able to reach levels achieved prior to the disruption. Our insurance policies may not fully insure against all potential causes of disruption due to limitations and exclusions in those policies. Therefore, incidents that significantly disrupt our operations may expose us to significant losses and/or liabilities.

If we are not able to continue the technological innovation and successful commercial introduction of new products, our customers may turn to other producers to meet their requirements.

Our industry and the end markets into which we sell our products experience periodic technological changes and ongoing product improvements. Our customers may introduce new generations of their own products or require new technological and increased performance specifications that would require us to develop customized products. Our future growth will depend on our ability to predict and react to changes in key end markets, and to successfully develop, manufacture and market products in such changing end markets. We need to continue to identify, develop and market innovative products on a timely basis to replace existing products in order to maintain our profit margins and our competitive position. We may not be successful in developing new products and technology that successfully compete with these materials, and our customers may not accept any of our new products. We may also face regulatory or operational difficulties in our ability to scale up new technologies, including recycling technology, to meet customer demand or keep up with competition. If we fail to keep pace with evolving technological innovations or fail to modify our products in response to our customers’ needs, then our business, financial condition and results of operations could be adversely affected as a result of reduced sales of our products.

If we are unable to execute on our capital projects, growth or maintenance projects within their expected budget and timelines, or if the market conditions assumed in our projections deteriorate, our business, financial condition, results of operations and cash flows could be materially and adversely affected.

We rely on capital projects, including plant improvements, maintenance activities, turnaround projects, and growth initiatives, to maintain the reliability of our operations and support our long-term strategy. Our recent actions to close certain underperforming or uncompetitive plants and product lines and exit from underperforming assets have reduced overall capital expenditure requirements. Further, we have proactively reduced capital expenditures in response to our financial performance, capital allocation priorities, and elevated borrowing costs. Operating with this reduced capital spending may increase the risk of equipment failures, unplanned outages, or delays in implementing operational improvements, any of which could adversely affect our production capabilities, costs, and financial results.

Capital projects and other investments often require long lead times, and market conditions may change materially between the approval of a project and its completion, negatively affecting expected returns. Decisions to defer, scale back, or cancel projects due to liquidity constraints, credit-rating considerations, or other financial pressures may limit

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our ability to maintain or enhance our manufacturing capabilities, pursue strategic initiatives, or respond to market opportunities.

In addition, delays or cost increases related to engineering, procurement, and construction activities, or to the development of new technologies, could materially adversely affect our ability to achieve forecasted operating results. Project delays or budget overruns may arise from factors beyond our control, including:

● delays in obtaining required regulatory approvals, licenses, or permits;

● increases in the cost of construction materials, labor, or utilities;

● transportation disruptions affecting components or materials;

● disease outbreaks and related governmental responses;

● shortages of skilled labor or labor disputes; or

● non‐performance or disputes with vendors, suppliers, contractors, or partners

If we are unable to execute capital projects within expected budgets or timelines, or if market conditions deteriorate during the project period, our business, financial condition, results of operations, and cash flows could be materially and adversely affected.

Risks Related to Acquisitions and Dispositions

We may not be successful in the proposed divestiture of our interest in Americas Styrenics.

In 2024 we announced that we had commenced a sale process for our interest in Americas Styrenics LLC, pursuant to an ownership exit provision in our joint venture agreement. We may not be able to accurately estimate the timing of the Americas Styrenics sale process or signing of a final agreement, valuation or purchase price, or whether economic or other market conditions will impact the timing, price or market interest. We cannot estimate whether economic conditions, capital markets, or other factors will allow us to successfully complete the sale of Americas Styrenics, or to locate an adequate buyer or buyers for our remaining styrenics business, negotiate terms of a sale acceptable to the Company or successfully complete such sale.

A successful divestiture depends on various factors, including our ability to effectively transfer liabilities, contracts, facilities and employees to any purchaser, revise our legal entity structure, negotiate continued equity ownership, identify and separate intellectual property, reduce fixed costs previously associated with the divested assets or business, and collect the proceeds from any sale. Any divestiture may result in a dilutive impact to our future earnings if we are unable to offset the dilutive impacts from the loss of revenue associated with the divested business, as well as significant write-offs, including those related to long-lived assets, including goodwill and other intangible assets, which could have a material adverse effect on our results of operations and financial condition. All of these efforts require varying levels of management resources, which may divert our attention from other business operations.

Joint ventures may not operate according to their business plans if we or our partners fail to fulfill our or their obligations, or differences in views among our joint venture partners result in delayed decisions, which may adversely affect our results of operations and may force us to dedicate additional resources to these joint ventures.

For the year ended December 31, 2025, we received dividends of $12.5 million from our Americas Styrenics joint venture. We may enter into additional joint ventures in the future. The nature of a joint venture requires us to share control with unaffiliated third parties. If joint venture partners do not fulfill their obligations, the affected joint venture may not be able to operate according to its business plan. In that case, our results of operations may be adversely affected and we may be required to increase the level of our commitment to the joint venture. Differences in views among joint venture participants and our inability to unilaterally implement sales and production strategies or determine cash distributions from joint ventures may significantly impact short-term and longer-term financial results, financial condition and the value of our ordinary shares.

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We may fail to realize the anticipated benefits of acquisitions or such benefits may take longer to realize than expected, and we may encounter difficulty integrating these businesses into our operations. We may also be required to incur impairment and other charges, which would adversely affect our operating results.

Our ability to realize the anticipated benefits of acquisitions will depend on our ability to successfully integrate the underlying businesses into ours. The Company has devoted significant attention and resources integrating the operations, systems, processes and procedures of the acquired businesses, and we expect to continue to do so. If we fail to effectively integrate or grow acquired businesses, we could lose or diminish the expected benefits of these acquisitions. We also face risks that we fail to meet our financial and strategic goals, due to, among other things, inability to grow the acquired business, achieve expected margins and grow relationships with customers. Further, these acquisitions may not result in the realization of the cost and revenue synergies and benefits that we expected at the time of the acquisitions, nor can we give assurances that these benefits will be achieved when expected or at all.

These risks may force us to write down the book value of underperforming acquired businesses. We may also be adversely affected by other economic, business, and/or competitive factors which did not exist at the time of closing. Such conditions could materially adversely impact our business and results of operations.

We may engage in other future strategic disposition or acquisitions of certain assets and/or businesses that could affect our business, results of operations, financial condition and liquidity.

We may selectively pursue collaboration agreements, joint ventures or complimentary acquisitions which inherently involves a number of risks and presents financial, managerial and operational challenges, including, but not limited to:

● difficulty maintaining relationships with customers;

● hiring additional management and other critical personnel;

● generating expected cost savings and synergies from the acquisition; and

● increasing the scope, geographic diversity and complexity of our operations.

Also, the presence of one or more material liabilities of an acquired company that are unknown to us at the time of acquisition may have a material adverse effect on our business or financial results. Our acquisition and joint venture strategy may not be successfully received by customers or other stakeholders, and we may not realize any anticipated benefits from these other acquisitions or joint ventures.

We may pursue dispositions of certain other assets and/or businesses, which may involve material amounts of assets or lines of business, and adversely affect our results of operations, financial condition and liquidity. If any such dispositions were to occur, under the terms of our outstanding third party indebtedness we may be required to apply the proceeds of the sale to repay any borrowings under such facilities and may also involve continued financial involvement in the divested business, such as through continuing equity ownership, transition service agreements, supply agreements, guarantees, indemnities or other current or contingent financial obligations.

Risks Related to Regulation and Compliance

We are subject to customs, international trade, export control, and antitrust laws that could require us to modify our current business practices and incur increased costs.

We are subject to numerous regulations, including customs and international trade laws, export/import control laws, and associated regulations. These laws and regulations limit the countries in which we can do business; the persons or entities with whom we can do business; the products which we can buy or sell; and the terms under which we can do business, including anti-dumping restrictions. In addition, we are subject to antitrust laws and zoning and occupancy laws that regulate manufacturers generally and/or govern the importation, promotion and sale of our products, the operation of factories and warehouse facilities and our relationship with our customers, suppliers and competitors. If any of these laws or regulations were to change or were violated by our management, employees, suppliers, buying agents or trading companies, the costs of certain goods could increase, or we could experience delays in shipments of our goods, be subject to fines or penalties, or suffer reputational harm, which could reduce demand for our products and hurt our business and negatively impact results of operations. In addition, in some areas we benefit from certain trade protections,

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including anti-dumping protection and the EU’s Authorized Economic Operator program, which provides expedited customs treatment for materials crossing national borders. If we were to lose these protections, our results of operations could be adversely affected.

Global trade conflicts and the imposition of tariffs may have a material adverse impact on our business and results of operations.

Various governments have adopted or may adopt protectionist trade policies seeking to impose tariffs, or renegotiate or terminate certain existing trade relationships or trade agreements. During 2025, the Trump administration announced and changed tariff polices on certain goods imported to the United States. The tariff landscape is continually changing and varies by country. We are not able to predict whether such tariffs will be permanent, whether new tariffs will be implemented or which jurisdictions would be impacted. In addition, recent U.S. Supreme Court decisions addressing executive authority and administrative rulemaking have added further uncertainty to the tariff and trade policy environment. Uncertainty over global tariffs has and may continue to delay purchasing decisions by our customers as they assess the impact of such trade policies on their business. Further changes in trade policy, trade restrictions, tariffs, or other governmental action have the potential to adversely impact our costs, including prices of raw materials, or demand for our products or our customers’ products, which in turn could adversely impact our business, financial condition and results of operations.

We could be subject to changes in the global and local tax regulatory environments in the jurisdictions in which we operate, which could adversely impact our results of operations.

We are subject to income taxes in Ireland, the United States, and numerous other foreign jurisdictions where our subsidiaries are organized. Due to economic and political conditions, tax rates in these jurisdictions may change significantly. Our effective tax rate in the future can be impacted by changes in the mix of earnings in countries with different statutory tax rates, changes in the valuation of deferred tax assets and liabilities, changes in tax laws or their interpretations, and other administrative or judicial rulings, and changes to our uncertain tax positions. Our tax returns are subject to examination by local tax authorities and other governmental bodies. We regularly assess the probability of an adverse outcome resulting from these examinations when determining our provision for income taxes. There is an inherent uncertainty to the outcome of these examinations. If it is determined that the taxes we owe are in excess of amounts previously accrued, our operating results and cash flows could be adversely affected.

Effective from 2024, the Organization for Economic Co-operation and Development’s Global Anti-Base Erosion rules under Pillar Two have been enacted by the European Union and other countries in which the Company operates. These rules impose a global minimum corporate tax rate of 15% on multinational enterprises. As the OECD continues to update their administrative guidance, additional jurisdictions enact similar legislation, transitional relief expires, and other provisions and guidance of Pillar Two go into effect, our effective tax rate and cash tax payments could increase in future years which could have an adverse impact on our future operating results and cash flows.

Regulatory and statutory changes, including those related to climate change and sustainability, applicable to our raw materials and products or our customers’ products, or changes to consumer preferences or public perception, could require material expenditures, changes in our operations and could adversely affect our financial condition and results of operations.

Changes in environmental, health and safety regulations in jurisdictions where we manufacture and sell our products could lead to a decrease in demand for our products. In addition to changes in regulations, customers, investors and other stakeholders are increasingly focusing on environmental issues and disclosures, including climate change, energy and water use, greenhouse gas emissions and other sustainability concerns. Change in public sentiment may result in changing demands for our products or could cause changes in the market dynamics of our existing products, impacting pricing, or cause us to incur additional costs to make changes to our operations to comply with such demand changes. Compliance with new regulations could increase the costs incurred to manufacture our products, or costs incurred by our customers to use our products and otherwise limit the use of these products and lead to decreased demand which would have an adverse effect on our business and results of operations. Our inability to meet investor, industry or stakeholder sustainability goals could materially impact our financial condition and results of operations.

Materials such as acrylonitrile, ethylbenzene, styrene, butadiene, bisphenol-A (“BPA”), MMA, UV-stabilizers, and halogenated flame retardant and others are used in the manufacturing of our products and have come under scrutiny due

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to potentially significant or perceived health and safety concerns. In addition, per- and polyfluoroalkyl substances (“PFAS”), chemicals used in products which require anti-dripping, temperature, chemicals, or fire resistance properties, are under heightened governmental and regulatory scrutiny in the U.S., Europe and other countries for potential contamination of soil, air and water, specifically in drinking water. The hazard classification of our products, or materials in our products, could change due to new data or toxicology studies, which may make sales of such products difficult to certain customers or in certain markets if we are unable to manufacture products without such classified materials. Heightened regulatory scrutiny, consumer protection actions or customer disapproval of these types of materials could lead to regulatory action or declining sales and could adversely affect our results of operations and financial condition.

Moreover, bans on single-use plastic, restrictions on microplastics and similar regulatory actions to reduce plastic waste and influence consumer preferences for sustainable and recyclable materials may reduce the demand for some of our products over time. New or proposed legislation addressing the global challenge of plastic waste may place responsibility on producers and sellers to include recycled content in their products. This legislation or other market factors, may impact our sales and place more importance on our initiatives to further develop technologies for recycled products.

Additionally, these regulatory regimes currently require significant compliance expenditures and future regulatory changes applicable to our raw materials and products or our customers’ products, could require significant additional expenditures or changes in our operations. Governmental inquiries or lawsuits involving these chemicals could lead us to incur liability for damages or other costs, lead to civil proceedings, the imposition of fines and penalties, or other remedies, and potentially add costs or restrictions to our manufacturing operations in the future.

Our products are also used in a variety of end-uses that have specific regulatory requirements such as those relating to products that have contact with food or medical device end-uses. Our customers or distributors may not follow our policies and advice regarding the safe use and application of our products, which may unknowingly expose us to third-party claims. We and many of the applications for the products in the end markets in which we sell our products are regulated by various national and local rules, laws and regulations, such as the U.S. Toxic Substances Control Act and the EU’s Registration, Evaluation, Authorisation and Restriction of Chemicals regulations. An increasing number of countries continue to adopt similar requirements, which could require significant compliance expenditures or changes to our sales and marketing strategies and operations. Changes to existing regulations could result in additional compliance costs, seizures, confiscations, recall or monetary fines, any of which could prevent or inhibit the development, distribution and sale of our products. Changes in environmental and safety laws and regulations banning or restricting the use of these residual materials in our products, or our customers’ products, could adversely affect our results of operations and financial condition. Failure to appropriately manage safety, human health, product liability and environmental risks associated with our products, product life cycles and production processes could adversely impact employees, communities, stakeholders, our reputation and the results of our operations.

Compliance with extensive and evolving environmental, health and safety laws may require substantial expenditures.

We use large quantities of hazardous substances, generate hazardous waste and emit wastewater and air pollutants in our manufacturing operations. Consequently, our operations are subject to extensive environmental, health and safety laws and regulations at both the national and local level in multiple jurisdictions. Many of these laws and regulations have become more stringent over time and the costs of compliance with these requirements may continue to increase, including costs associated with any capital investments for pollution control facilities. In addition, our production facilities and operations require operating permits, licenses or other approvals that may be subject to periodic renewal and, in circumstances of noncompliance, may be subject to revocation. The necessary licenses, permits or other approvals may not be issued or continue in effect, and any issued licenses, permits or approvals may contain more stringent limitations that restrict our operations or that require further expenditures to meet the permit requirements.

This continuing focus on climate change in jurisdictions in which we operate has and will continue to result in new environmental regulations that may require us to incur additional costs in complying with new regulatory and customer requirements, which may adversely impact our operations and financial condition. Compliance with more stringent environmental requirements would likely increase our costs of transportation and storage of raw materials and finished products, as well as the costs of storage and disposal of waste. Additionally, we may incur substantial costs, including penalties, fines, damages, criminal or civil sanctions and remediation costs for the failure to comply with these laws or permit requirements.

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We may be subject to losses due to liabilities or lawsuits related to contaminated land we own or operate or arising out of environmental damage or personal injuries associated with exposure to chemicals or the release of chemicals.

Under the Comprehensive Environmental Response, Compensation and Liability Act (“CERCLA”) and similar statutes outside the U.S., the current or former owner or operator of a property contaminated by hazardous substance releases is subject to strict, unlimited, joint, several and retroactive liability for the investigation and remediation of the property, and also may be liable for natural resource damages associated with the releases. In addition to potential statutory liability, we also face the risk that individuals could seek damages for personal injury due to exposure to chemicals at our facilities, chemicals which have been released from our facilities, chemicals otherwise owned or controlled by us, or chemicals which allegedly migrated from products containing our materials. We face ongoing regulatory action by certain government agencies related to a spill at our Bristol site (see Item 3—Legal Proceedings). We may be subject to claims with respect to workplace exposure, workers’ compensation and other health and safety matters. Legal claims and regulatory actions could subject us to both civil and criminal penalties, which could affect our reputation as well as our results of operations, financial condition, and liquidity.

There are several properties which we own on which Dow has been conducting remediation to address historical contamination, while there are other properties with historical contamination that are owned by Dow that we lease for our operations. While we did not assume the liabilities associated with these properties in the U.S., because CERCLA and similar laws can impose liability for contamination on the current owner or operator of a property, even if it did not create the contamination, there is a possibility that a governmental authority or private party could seek to include us in an action or claim for remediation or damages, even though the contamination may have occurred prior to our ownership or occupancy. While Dow has agreed to indemnify us for liability for releases of hazardous materials that occurred prior to our separation from Dow, the indemnity is subject to monetary and temporal limitations. The period for new claims at these sites has expired. Sites acquired after the Dow Separation are subject to a different limitations period or may not be subject to any indemnification. We cannot be certain that Dow will fully honor the indemnity or that the indemnity will be sufficient to satisfy all claims that we may incur. Any active remedial projects on our properties which were part of the Dow Separation are being performed by Dow pursuant to its indemnification obligations. In addition, we face the risk that future claims might fall partially or fully outside of the scope of the indemnity, particularly if there is a release of hazardous materials that occurs in the future or at any time after our separation from Dow or if the condition requiring remediation is attributable to a combination of events or operations occurring prior to and after our separation from Dow. The Company believes it has set adequate reserves for all remediation projects it is currently undertaking.

Risks Related to Litigation

We are party to certain legal proceedings, and may be subject to additional litigation, arbitration or legal proceedings in the future.

From time to time, we may be involved in litigation, arbitration or other legal proceedings relating to claims arising out of our operations, business, including but not limited to disputes over prior dispositions or other transactions, disputes over pricing or payments, or disputes over service or maintenance costs at sites we do not own. The results of any current or future legal proceedings cannot be predicted with certainty and, regardless of the outcome, we may incur significant costs and experience a diversion of management resources as a result of such proceedings. The results of any such proceedings could have a material adverse impact on our business, financial condition, cash flows and results of operations.

The Company records accruals for legal matters which are both probable and reasonably estimable, and the Company believes that it has adequately accrued for ongoing legal matters as appropriate. Litigation and arbitration are inherently unpredictable and, although the Company believes that its accruals are adequate and/or that it has valid defenses in such matters, unfavorable resolutions could occur that are in excess of amounts accrued or which could have a material adverse effect on the Company’s financial condition, results of operations or cash flows.

Risks Related to Our Relationship with Dow

Dow provides significant operating and other services, and certain raw materials used in the production of our products, under agreements that are important to our business. The failure of Dow to perform its obligations, or the termination of these agreements, could adversely affect our operations.

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Prior to the Dow Separation, we were operated by Dow, which has provided and continues to provide services under certain agreements that are important to our business. We are a party to (i) SAR SSAs; (ii) supply and sales agreements; and (iii) the AR MOD5 Agreement, the terms of which permit either party to terminate the applicable agreement in a variety of situations, including in the event of the other party’s uncured material breach, insolvency, change of control or cessation of operations. Should Dow fail to provide these services or raw materials, or should any of the above agreements be terminated, we would be forced to obtain these services and raw materials from third parties or provide them ourselves. Additionally, if Dow terminates agreements pursuant to which we are obligated to provide certain services, we may lose the fees received by us under these agreements. The failure of Dow to perform its obligations under, or our inability to renegotiate, renew or replace any of these contracts, particularly without an alternative source of raw materials, could adversely affect our operations. Depending on market conditions at the time of any such termination, we may not be able to enter into substitute arrangements in a timely manner. For more information regarding our relationship with Dow, please see Item 1—Business — Our Relationship with Dow.

We are party to certain license agreements with Dow relating to intellectual property that is essential to our business. Because of this relationship, we may have limited ability to expand our use of certain intellectual property beyond the field of the license or to police infringement that may be harmful to our business.

In connection with the Dow Separation, we acquired ownership of, or in some cases, a worldwide right and license to use, certain patents, patent applications and other intellectual property of Dow that were used by Dow to operate our business segments or held by Dow primarily for the benefit of our business segments, prior to the Dow Separation. Generally, we acquired ownership of the intellectual property that was primarily used in our business segments and acquired a license to a more limited set of intellectual property that had broader application within Dow beyond our core business segments. Our license from Dow is perpetual, irrevocable, fully paid, and royalty-free. Furthermore, our license from Dow is exclusive within our business segments for certain patents and patent applications that were used by Dow primarily prior to our separation, subject to licenses previously granted by Dow, and to certain retained rights of Dow, including Dow’s retained right to use patents and patent applications outside of our business segments and for internal consumption by Dow. Our license from Dow relates to polymeric compositions, manufacturing processes and end applications for the polymeric compositions; and is limited to use in defined areas corresponding to our current business segments excluding certain products and end-use application technology retained by Dow. Our ability to develop, manufacture or sell products and technology outside of these defined areas may be impeded by the intellectual property rights that have been retained by Dow, which could adversely affect our business, financial condition and results of operations. Additionally, infringement on these intellectual property rights could also impact our business and competitive position. We may not be able to enforce our rights, and Dow may be unwilling to enforce its rights, with respect to this intellectual property that has been licensed by Dow.

Risks Related to Our Intellectual Property

Our business relies on intellectual property and other proprietary information and our failure to adequately protect or effectively enforce our rights, or our ability to successfully license our intellectual property, could harm our competitive advantages with respect to the manufacturing of some of our products.

Our success depends to a significant degree upon our ability to protect, preserve and enforce our intellectual property rights, including patents, trademarks, licenses, trade secrets and other proprietary information of our business. However, we may be unable to prevent third parties from using our intellectual property and other proprietary information without our authorization or independently developing intellectual property and other proprietary information that is similar to or competes with ours. Any inability by us to effectively prevent the unauthorized use of our intellectual property and other proprietary information by others could reduce or eliminate any competitive advantage we have developed, cause us to lose sales or otherwise harm our business or goodwill. If it becomes necessary for us to initiate litigation to protect our proprietary rights, any proceedings could be burdensome and costly, and we may not prevail.

We may be unable to determine when third parties are using our intellectual property rights without our authorization, particularly our manufacturing processes. In addition, we cannot be certain that any intellectual property rights that we have licensed to third parties are being used only as authorized by the applicable license agreement. The undetected, unremedied, or unauthorized use of our intellectual property rights or the legitimate development or acquisition of intellectual property that is similar to or competes with ours by third parties could reduce or eliminate the

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competitive advantage we have as a result of our intellectual property, adversely affecting our financial condition and results of operations.

We have licensed certain intellectual property and proprietary manufacturing processes to a third party as part of a sale and license of our polycarbonate manufacturing plant assets in Stade, Germany. Our inability to enforce our licensing rights or ownership of our intellectual property could have an adverse effect on our financial condition.

If we fail to adequately protect our intellectual property and other proprietary information, including our processes, apparatuses, technology, trade secrets, trade names and proprietary manufacturing know how, methods and compounds, through obtaining patent protection, securing trademark registrations and securing our trade secrets through the use of confidentiality agreements of appropriate scope and other means, our competitive advantages over other producers could be materially adversely affected. If we determine to take legal action to protect, defend or enforce our intellectual property rights, any suits or proceedings could result in significant costs and diversion of our resources and our management’s attention. We may not prevail in any such suits or proceedings. A failure to protect, defend or enforce our intellectual property rights could have an adverse effect on our financial condition and results of operations.

Our products may infringe the intellectual property rights of others, which may cause us to incur unexpected costs or prevent us from selling our products.

Many of our competitors have a substantial amount of intellectual property that we must continually strive to avoid infringing as we improve our own business processes and develop new products and applications. Although it is our policy and intention not to infringe valid patents of which we are aware, we cannot provide assurances that our processes and products and other activities do not and will not infringe issued patents (whether present or future) or other intellectual property rights belonging to others. There nonetheless could be third-party patents that cover our products, processes or technologies, and it is possible that we could be liable for infringement of such patents and could be required to take remedial or curative actions to continue our manufacturing and sales activities with respect to one or more products that are found to be infringing. We may also be subject to indemnity claims by our business partners arising out of claims of their alleged infringement of the patents, trademarks and other intellectual property rights of third parties in connection with their use of our products. Intellectual property litigation often is expensive and time-consuming, regardless of the merits of any claim, and our involvement in such litigation could divert our management’s attention from operating our business. If we were to discover that any of our processes, technologies or products infringe on the valid intellectual property rights of others, we may not be able to obtain the necessary licenses on acceptable terms, or at all, or be able to modify our processes or technologies or re-engineer our products in a manner that is successful in avoiding infringement. Moreover, if we are sued for infringement and lose, we could be required to pay substantial damages and/or be enjoined from using or selling the infringing products or technology. Any of the foregoing could cause us to incur significant costs and prevent us from selling our products and could have an adverse effect on our financial condition and results of operations.

Risks Related to Data Security

Cybersecurity incidents including data breaches could compromise confidential information related to our business or the private information of our employees, vendors, and customers, or could negatively impact our operations, which could adversely affect our business and our reputation.

Cybersecurity incidents including data breaches could compromise our confidential information, personal identifiable information (“PII”) of our employees, vendors, or customers, or cause a failure of our computer systems. A cyber security incident or data breach could result in the loss of confidential information or PII, and could negatively impact business operations and pose a negative impact on our operations, reputation or financial results. Such incidents may result from external threats including cyber-attacks by criminal groups, state-sponsored actors or social-activist (hacktivist) organizations or internal threats including malicious employees, mishandled information or inappropriate access. Cybersecurity threats are constantly evolving, becoming more sophisticated and being made by groups and individuals with a wide range of expertise and motives, increasing the difficulty of detecting and successfully defending against them. Furthermore, in addition to using our computer systems, we rely on computer systems operated by third-party service providers. If our third-party service providers experience a cybersecurity incident, it could compromise our confidential information or cause a disruption in our operations. A cybersecurity incident or breach of our systems, or that of a third-party service provider, could lead to ransom, shutdown or destruction of our critical manufacturing systems, manufacturing downtimes or operational disruptions, and other significant costs, which could adversely affect

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our reputation, financial condition and results of operations. In addition, the loss or disclosure of PII of our employees, vendors, or customers as a result of a data breach may result in violations of various data privacy regulations and expose us to litigation, fines and other penalties. Therefore, any such cybersecurity incident, disruptions to our operations or violations of data privacy laws could negatively impact our business, reputation and results of operations.

Risks Related to our Information Systems

The suspension of a new enterprise resource planning (“ERP”) system implementation could cause disruption to our operations.

We began a multi-year transition to a new ERP system intended to replace most of our core financial systems, but the project was paused in 2023 as a cost-control measure and has not restarted. At this time, we do not expect the project to resume in the foreseeable future. The continued suspension of the ERP implementation, or any future restart that does not proceed as planned or fails to operate as intended, could negatively affect the effectiveness of our internal control over financial reporting. These types of disruptions could adversely impact our business, operating results, and financial condition. Additionally, if the ERP project is eventually reinitiated, significant resources and further refinement may be required to achieve the anticipated benefits.

Risks Related to Our Ordinary Shares

Irish law differs from the laws in effect in the U.S. and may afford less protection to holders of our securities than companies formed in the U.S.

It may not be possible to enforce court judgments obtained in the U.S. against us in Ireland based on the civil liability provisions of the U.S. federal or state securities laws. In addition, there is some uncertainty as to whether the courts of Ireland would recognize or enforce judgments of U.S. courts obtained against us or our directors or officers based on the civil liabilities provisions of the U.S. federal or state securities laws or hear actions against us or those persons based on those laws. There is no treaty between Ireland and the U.S. providing for the reciprocal enforcement of foreign judgments. Therefore, a final judgment for the payment of money rendered by any U.S. federal or state court based on civil liability, whether or not based solely on U.S. federal or state securities laws, would not automatically be enforceable in Ireland.

As an Irish company, Trinseo is governed by the Irish Companies Acts, which differ in some material respects from laws generally applicable to U.S. corporations and shareholders, including, among others, differences relating to interested director and officer transactions and shareholder lawsuits. Likewise, the duties of directors and officers of an Irish company generally are owed to the company only. Shareholders of Irish companies generally do not have a personal right of action against directors or officers of the company and may exercise such rights of action on behalf of the company only in limited circumstances. Accordingly, holders of our shares may have more difficulty protecting their interests than would holders of securities of a corporation incorporated in a jurisdiction of the U.S.

Provisions of our articles of association and Irish law could delay or prevent a takeover of us by a third party.

Our articles of association could delay, defer or prevent a third-party from acquiring us, despite the possible benefit to our shareholders. For example, our articles of association impose advance notice requirements for shareholder proposals and nominations of directors to be considered at shareholder meetings, and our articles also require supermajority approval from shareholders to amend or repeal our articles of association.

In addition, several mandatory provisions of Irish law could prevent or delay an acquisition of Trinseo. For example, Irish law does not permit shareholders of an Irish public limited company to take action by written consent with less than unanimous consent. We are also subject to provisions of Irish law relating to mandatory bids, voluntary bids, requirements to make a cash offer and minimum price requirements, as well as rules requiring the disclosure of interests in our ordinary shares in certain circumstances.

These provisions may discourage potential takeover attempts, discourage bids for our ordinary shares at a premium over the market price, and may negatively impact the voting and other rights of our shareholders. These provisions could also discourage proxy contests and make it more difficult for our shareholders to elect directors other than those nominated by our board of directors.

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Any attempts to take us over will be subject to Irish Takeover Rules and subject to review by the Irish Takeover Panel.

We are subject to the Irish Takeover Rules, under which our board of directors will not be permitted to take any action which might frustrate an offer for our ordinary shares once it has received an approach which may lead to an offer or has reason to believe an offer is imminent.

As an Irish public limited company, certain capital structure decisions regarding the Company will require the approval of shareholders, which may limit the Company’s flexibility to manage its capital structure.

Irish law provides that a board of directors may allot shares (or rights to subscribe for or convertible into shares) only with the prior authorization of shareholders, for a maximum period of five years, as specified in the articles of association or relevant shareholder resolution. At our most recent annual general meeting, shareholders authorized the allotment of up to 20% of the nominal value of the Company’s issued ordinary share capital for a period of 18 months. Approval from the Company’s shareholders, by ordinary resolution, being a resolution passed by a simple majority of votes cast, on or prior to expiration, will be required to renew this authorization. Our ability to issue equity without this authorization could be limited which could adversely affect our securities holders.

Irish law also generally provides shareholders with preemptive rights when new shares are issued for cash; however, it is possible for the Company’s articles of association, or shareholders in general meeting, to exclude preemptive rights. At our most recent annual general meeting, shareholders authorized the exclusion of preemptive rights for a period of 18 months for (i) the issuance of shares for cash in connection with any rights issue; and (ii) the issuance of shares for cash not to exceed 5% of our issued ordinary share capital (with an additional 5% provided the company uses it for an acquisition or specified capital investment). Renewal of this exclusion requires approval by Company’s shareholders, by special resolution, being a resolution passed by not less than 75% of votes cast, on or prior to expiration. Should this exclusion not be approved, our ability to issue equity could be limited which could adversely affect our securities holders.

General Risks

Conditions in the global economy and capital markets may adversely affect our results of operations, financial condition and cash flows.

Our products are sold in markets that are sensitive to changes in general economic conditions, such as sales of automotive and construction products. Downturns in general economic conditions can cause fluctuations in demand for our products, product prices, volumes and margins.

Trinseo PLC TSEOQ US Equity

TSEOQ · 10-K · period ended 2025-12-31

Item 1. Business

Item 1A. Risk Factors

Trinseo PLC TSEOQ US Equity☆

TSEOQ · 10-K · period ended 2025-12-31

Item 1. Business

Item 1A. Risk Factors

Trinseo PLC TSEOQ US Equity