NYSE: WLK

We began operations in 1986 and since then, we have grown rapidly into an integrated global producer of building products and chemicals through effectively executing our growth strategy.

In 2014, we formed Westlake Chemical Partners LP ("Westlake Partners") to operate, acquire and develop ethylene production facilities and related assets. Also in 2014, Westlake Partners completed an initial public offering of common units (the "Westlake Partners IPO"). As of February 18, 2026, Westlake Partners' assets consisted of a 22.8% limited partner interest in Westlake Chemical OpCo LP ("OpCo"), as well as the general partner interest in OpCo. OpCo's assets include two ethylene production facilities at our olefins facility in Lake Charles, Louisiana, one ethylene production facility at our Calvert City, Kentucky site and a 200-mile common carrier ethylene pipeline that runs from Mont Belvieu, Texas to the Longview, Texas site, which includes our Longview polyethylene production facility. We retain a 77.2% limited partner interest in OpCo, a 40.1% limited partner interest in Westlake Partners (consisting of 14,122,230 common units), a general partner interest in Westlake Partners and incentive distribution rights. The operations of Westlake Partners are consolidated in our financial statements. We are party to certain agreements with Westlake Partners and OpCo whereby, among other items, OpCo sells us 95% of the ethylene it produces on a cost-plus basis that is expected to generate a fixed margin per pound of $0.10. We use this ethylene in the production processes of our Performance and Essential Materials segment.

Since 2022, we own an aggregate 50% membership interest in LACC, LLC ("LACC"), which owns an ethylene plant that is adjacent to our chlor-alkali facility in Lake Charles and has 2.2 billion pounds per year of ethylene production capacity. We receive our proportionate share of LACC's ethylene production on a cash-cost basis, which benefits our integrated downstream operations.

We have grown organically and completed multiple acquisitions as we seek to either expand our existing business or add new complementary businesses. In 2016, we completed the acquisition of Axiall Corporation ("Axiall"), a manufacturer and international marketer of chemicals and building products with manufacturing sites in North America, for purchase consideration of approximately $2.5 billion.

In 2021, we completed the acquisition of Boral Limited's North American building products businesses in roofing; siding; trim; and shutters; decorative stone; and windows for total consideration of approximately $2.1 billion. In 2022, we completed the acquisition of the global epoxy business of Hexion Inc. ("Westlake Epoxy") for total consideration of approximately $1.2 billion. In 2025, we completed the expansion of chlorine, caustic soda and VCM productions capacities at our Geismar, Louisiana site. In January 2026, we acquired the global compounding solutions businesses of the ACI/Perplastic Group (collectively, "ACI"). ACI, a Portugal-based manufacturer of specialty materials serving the wire and cable sectors with manufacturing locations in Portugal, Mexico, Tunisia and Romania.

Sustainability

We are continually seeking ways to enhance the safety, efficiency, and overall impact of our operations on our employees, the communities where we operate, and the environment. We endeavor to produce and deliver our products in increasingly sustainable ways, to reduce the environmental footprint of our operations and to develop products with improved sustainability features. To achieve these objectives, we continue to focus on recycling opportunities within our businesses, reducing waste at our facilities, incorporating more recycled content into our products, seeking to incorporate renewable and bio-based materials, and producing products that support greater efficiency and durability.

Housing and Infrastructure Products Business

Our HIP segment is primarily comprised of residential and non-residential building products, PVC pipe and fittings, and compound products made from PVC and other polymers.

Our Brands and Products

We manufacture and sell housing and infrastructure products including residential PVC siding; PVC trim and mouldings; architectural stone veneer; windows; PVC decking; polymer composite and cement roof tiles; PVC pipe and fittings for various water, sewer, electrical and industrial applications; compounds used in various housing, medical and automobile products; and a variety of consumer and commercial products such as landscape edging; industrial, home and office matting; marine dock edging; and masonry joint controls.

Our HIP business consists of several product groups including: (i) exterior and interior building products, which includes siding, trim and mouldings, stone, roofing, windows and outdoor living products; (ii) PVC pipe, specialty PVC pipe and fittings; and (iii) compounds primarily made from PVC. Many of our products are made from PVC, including PVC products for water and sewer systems and home and light commercial applications for siding, trim and mouldings, outdoor living products, windows and PVC compounds.

Siding. Our siding products include insulated siding and vinyl siding and accessory products. Additionally, we offer premium siding products such as Celect® Cellular Composite Siding, TruExterior® Siding and Cedar Renditions™ Siding. Our siding business is also a leader in non-wood shutters and siding accessories along with an array of specialty tools to aid installation. Our brands include Royal® Siding, Portsmouth® Shake and Shingle, Foundry® Specialty Siding, TruExterior Siding & Trim, Celect Cellular Exteriors, Mid-America® Exteriors, Tapco Tools®, and many more.

Trim and Mouldings. We offer a wide variety of trim and moulding products, including exterior and interior products for homes, multi-family and light commercial structures that are used as substitute for wood and wood composite offerings. Our brands include Royal Trim and Mouldings, TruExterior Siding & Trim, and Kleer Lumber®, among others.

Stone. We are a leader in the masonry stone veneer category, with both mortar applied products and mechanically fastened products that are used as a substitute for stone on exterior walls and accents as well as in interior applications such as fireplaces, kitchens and bathrooms. Our stone brands include Cultured Stone®, Eldorado Stone®, Versetta Stone®, StoneCraft Industries® and Dutch Quality Stone®.

Roofing. Our DaVinci® Roofscapes is a premium composite roofing. Additional product offerings include concrete and clay roof tiles and stone-coated steel roofing. Our other roofing brands include NewPoint™ Concrete Roof Tile, US Tile® Clay Roofing Products, and Unified Steel® Stone Coated Roofing, among others.

Windows. We are a regional fabricator of vinyl windows in the South and Southeast markets of the United States. Our brands include Legacy Collection™, the Krestmark® Collection, and the Magnolia Collection™.

Outdoor Living Products. Our outdoor living products include Zuri® Premium Decking.

PVC Pipe. We manufacture and sell PVC pipe ranging in sizes from ½ inch to 36 inches in diameter, in gasketed, solvent welded, and restrained joint configurations. Our pipe products are used in residential water and sewer applications; municipal potable water and sewer infrastructure; plumbing and industrial applications, including drain, waste and vent ("DWV"); electrical duct and conduit; turf irrigation, water well and other major water transport market segments. We manufacture and market pipe for water, sewer, irrigation and conduit pipe products under the Westlake Pipe & Fittings brand name.

Specialty PVC Pipe. Our specialty PVC pipe includes the Certa-Lok® pipe and Certa-Lok CLIC® joining systems, which provide restrained joints with rapid assembly, designed for use in potable water, sewer, fire protection, agriculture, well-casing, electrical conduit and other piping system applications in the residential and various infrastructure markets. Other specialty products include a system for high rise DWV installations that incorporates low-smoke and flame properties. Our molecularly-oriented PVC ("PVCO") pipe, AquaMax®, is produced with less PVC than conventional pipe improving our environmental footprint while delivering higher performance. We also manufacture and market specialty pipe under the Certa-Set®, Certa-Flo®, Certa-Com®, Yelomine®, Fluid-Tite®, Kwik-Set® and Sure-Fit® brand names, among others.

Fittings. Our fittings products include a range of injection-molded and custom fabricated-fittings including: injection mold DWV fittings for residential, low-rise and high-rise commercial installations; molded gasketed and solvent weld sewer fittings up to 12 inches, molded gasketed municipal pressure fittings and molded fittings for the pool, spa, industrial markets and electrical assemblies; and fabricated custom fittings up to 36 inches for municipal and plumbing installations. We manufacture and market specialty fittings under the Westlake Pipe & Fittings brand name.

Compounds. Compounds are custom blended formulations made by combining PVC resin or other polymers with functional additives. They offer specific end-use properties based on customer-determined specifications and are used to produce rigid and flexible applications. Our compounds are processed (by our customers) via extrusion, injection molding, blow molding calendering. Our primary markets are building materials (housing), pipe and fittings, industrial materials, automotive, healthcare, telecommunications and consumer goods. Flexible compounds are used for, but not limited to, the following applications: wire and cable, flooring, roofing, wall coverings, window and door trims, gaskets, industrial applications, automotive interior and exterior trims, footwear and medical applications. Rigid extrusion compounds are commonly used for pipe, window and door profiles, fencing, decking, railing, siding and trim. Injection molding and blow molding compounds are commonly used for pipe fittings, electrical components, industrial applications and packaging for consumer goods. We manufacture and market custom compounds under the Westlake Global Compounds brand names.

Recycled Products. Westlake Dimex is a producer of post-industrial-recycled PVC, PE and thermoplastic elastomer (TPE) compounds in addition to various consumer and professional products made from recycled PVC, PE and TPE materials. These products include landscape edging; industrial, home and office matting; marine dock edging; and masonry control joints.

Raw Materials and Suppliers

Our North American PVC facilities in the PEM segment supply most of the PVC required for our housing exteriors and PVC pipe and fittings plants. Our raw materials for stone, roofing and accessories, windows, shutters, and specialty tool products are purchased externally. PVC required for the compounds plants is either internally sourced from our PEM segment or externally purchased based on the location of the plants. The remaining raw materials required, including pigments, fillers, stabilizers, and other ingredients, are typically purchased under short-term contracts, long-term contracts and in the spot market based on prevailing market prices.

Manufacturing

We operate 53 manufacturing facilities primarily in North America where we produce siding, trim and mouldings, stone, roofing, windows, outdoor living products, PVC pipes, specialty PVC pipe and fittings. We also operate 11 manufacturing facilities in North America, Europe and Asia where we produce compounds. The following table illustrates the properties owned and leased by the HIP business for manufacturing products:

Manufacturing Facilities

OwnedLeased

North America4315

Europe22

Asia2—

Marketing, Sales and Distribution

We sell a majority of our siding, trim and mouldings, stone, roofing, windows and outdoor living products, PVC pipe, specialty PVC pipe and fittings through a combination of our internal sales force and some external manufacturer's representatives. In North America, we operate 39 leased and 8 owned distribution centers, storage facilities and warehouses that service and supply these products to local customers, contractors and distributors. We also engage in advertising programs primarily directed at trade professionals and homeowners that are designed to increase awareness of and interest in our products. We also display our products at trade shows. Additionally, our 11 compounds manufacturing facilities across the world sell through a combination of our internal sales force and distributors.

No single customer accounted for 10% or more of net sales for the HIP segment in 2025.

Competition

Our HIP businesses operate in highly competitive markets. Competition in the housing and infrastructure products market is based on product quality and product innovation, technical support and customer service, product consistency, availability of potential substitute materials, on-time delivery and price. We compete in the housing and infrastructure products market with other producers and fabricators including Associated Materials LLC., CertainTeed Corporation, Cornerstone Building Brands, Inc., Diamond Plastics Corporation, IPEX Inc., JM Eagle Inc., Trex Company, Inc. and James Hardie, and with producers of compounds including GEON Performance Solutions and Teknor Apex Company, Inc.

Seasonality

Though we generally see demand for our products throughout the year, our sales have historically experienced some seasonality, particularly for our housing products. We have typically experienced moderately higher levels of sales of our residential products in the second and third quarters of the calendar year due to inventory restocking and improved weather for construction. Our sales are affected by the individual decisions of distributors and dealers on the levels of inventory they carry, their views on product demand, their financial condition and the manner in which they choose to manage inventory risk. Sales are also generally impacted by the number of days in a quarter or a year that contractors and other professionals are able to install our products. The number of days can vary dramatically based on, among other things, weather events such as rain, snow and extreme temperatures. We generally experienced lower levels of sales of our housing products in the fourth quarter due to adverse weather conditions in certain markets, which typically reduces the construction and renovation activity during the winter season.

Performance and Essential Materials Business

Our PEM products such as ethylene, PVC, polyethylene, epoxy and caustic soda are some of the most widely used materials in the world and are upgraded into a wide variety of higher value-added products used in many end-markets. We are one of the largest producers of chlor-alkali and PVC in the world, which makes us a leading global chlorovinyls producer. Our performance and essential materials are used by customers in PVC pipe applications; housing and construction products; food and specialty packaging; industrial and consumer packaging; renewable wind energy; coatings; consumer durables; medical health applications; and mobility and transportation, among others.

Chlor-alkali and petrochemicals are typically manufactured globally in large volume by a number of different producers using widely available technologies. We are a leading supplier of liquid and solid epoxy resins that are used in a wide variety of industrial coating applications. We are also one of the leading producers of epoxy specialty resins, modifiers and curing agents in Europe, the United States and Asia with a global reach to our end markets. Epoxy resins are the fundamental component of many types of materials and are often used in the automotive, construction, wind energy, aerospace and electronics industries due to their superior adhesion, strength and durability.

Products

Principal products in our integrated PEM segment include ethylene, PE, chlor-alkali (chlorine and caustic soda), chlorinated derivative products, ethylene dichloride ("EDC"), VCM and PVC. We manage our integrated vinyls production chain to optimize product margins and capacity utilization.

We manufacture ethylene through three of the OpCo plants and our portion of LACC's production capacity. These facilities are located in Lake Charles and Calvert City. Chlor-alkali materials are produced at our three plants located in Lake Charles, two plants located in Germany and one plant located in each of Calvert City, Geismar and Plaquemine, Louisiana, Natrium, West Virginia, Longview, Washington and Beauharnois, Quebec, Canada. Our VCM is produced at each of our plants at Calvert City, Plaquemine, Geismar and Lake Charles and two plants located in Germany. Our PVC is produced at our four plants located in Germany and one plant in each of Calvert City, Plaquemine and Geismar. Polyethylene and associated products are produced at our two PE plants in Lake Charles and three PE plants and a specialty PE wax plant at our Longview site. Our chlorinated derivative products are primarily produced at our plants in Lake Charles and Natrium. Epoxy Specialty Resins are produced at two plants located in Germany, two plants in the United States, one plant in Spain and one plant in South Korea. Base Epoxy Resins and Intermediaries are produced at our plant in Deer Park, United States. Our other Asian manufacturing facilities are located near Shanghai, in China, and in Kaohsiung, Taiwan, through our 95%- and 60%-owned joint ventures. As of February 18, 2026, we (directly and through OpCo, our investment in LACC, and our 95%- and 60%-owned joint ventures in China and Taiwan, respectively) had approximately 39.2 billion pounds per year of aggregate production capacity at numerous manufacturing sites in North America, Europe and Asia in our PEM segment.

The following table illustrates our PEM segment production capacities at February 18, 2026 by principal product and the end uses of these products:

Product (1)(5)

Annual Capacity (2)
End Uses
Principal Manufacturing Facilities (9)(10)

(Millions of pounds)

Ethylene (7)
4,820 VCM, polyethylene, EDC, styrene, ethylene oxide/ethylene glycolCalvert City, Kentucky

Lake Charles, Louisiana

Chlorine (4)(6)
6,670 VCM, EDC, organic/inorganic chemicals, bleach and water treatmentCalvert City, Kentucky

Geismar, Louisiana

Lake Charles, Louisiana

Plaquemine, Louisiana

Natrium, West Virginia

Gendorf and Knapsack, Germany

Caustic Soda (4)(6)
7,510 Pulp and paper, organic/inorganic chemicals, neutralization and aluminaCalvert City, Kentucky

Geismar, Louisiana

Lake Charles, Louisiana

Plaquemine, Louisiana

Natrium, West Virginia

Gendorf and Knapsack, Germany

VCM (4)(6)
7,630 PVC, PVC CompoundsCalvert City, Kentucky

Geismar, Louisiana

Lake Charles, Louisiana

Plaquemine, Louisiana

Gendorf and Knapsack, Germany

Specialty PVC980 Automotive sealants, cable sheathing, medical applications and other applicationsBurghausen, Cologne, and Gendorf, Germany

Commodity PVC (4)(8)
5,520 Construction materials including pipe, siding, profiles for windows and doors, film and sheet for packaging and other applicationsCalvert City, Kentucky

Geismar, Louisiana

Plaquemine, Louisiana

Cologne and Knapsack, Germany

Low-Density Polyethylene ("LDPE")1,500 High clarity packaging and bags, shrink films, food packaging, coated paper board, cup stock, paper folding cartons, lids, closures and general purpose moldingLake Charles, Louisiana

Longview, Texas

Linear Low-Density Polyethylene ("LLDPE")1,070 Heavy-duty films and bags, general purpose linersLake Charles, Louisiana

Longview, Texas

Chlorinated Derivative Materials2,280 Coatings, flavorants, films, refrigerants, water treatment applications, chemicals and pharmaceutical productionLake Charles, Louisiana

Natrium, West Virginia

Longview, Washington

Beauharnois, Canada

Product (1)(5)

Annual Capacity (2)
End Uses
Principal Manufacturing Facilities (9)(10)

(Millions of pounds)

Epoxy Specialty Resins580
Protective coatings and adhesive applications; building and bridge construction, flooring, transportation, oil & gas electrical applications; generators and bushings, transformers, medium and high-voltage switch gear components composites epoxy resins; wind energy, automotive, aerospace, construction, industrial applications

Lakeland, Florida

Argo, Illinois

Duisburg and Esslingen, Germany

Onsan, South Korea

Barbastro, Spain

Base Epoxy Resins and Intermediaries (3) (BERI)
610
Electrocoat; automotive, general industry powder coatings; white goods, pipes for oil and gas transmission, general industry heat cured coatings; metal packaging and coil coated steel for construction and general industry
Deer Park, Texas

______________________________

(1) EDC, a VCM intermediate product, is not included in the table.

(2) Includes capacity related to our 95%- and 60%-owned Asian joint ventures.

(3) Excludes production capacity related to our Pernis, Rotterdam, The Netherlands facility, which was closed in 2025. Annual production capacity of BERI associated with Pernis facility was approximately 675 million pounds.

(4) Excludes production capacity related to our chlorovinyl facilities that were closed in December 2025, including (i) our PVC plant at the Aberdeen, Mississippi site, which had an annual capacity of approximately 1.0 billion pounds of suspension PVC, (ii) our VCM plant at the Lake Charles, Louisiana North site, which had an annual capacity of approximately 910 million pounds of VCM, and (iii) one of our diaphragm chlor-alkali units at the Lake Charles, Louisiana site, which had an annual capacity of approximately 825 million pounds of chlorine and 910 million pounds of caustic soda.

(5) Excludes styrene production related to our styrene production plant located at the Lake Charles, Louisiana site, which was closed in December 2025 and had an annual production capacity of approximately 570 million pounds of styrene.

(6) Includes increased chlorine, caustic soda and VCM production capacities of 220 million pounds, 242 million pounds and 600 million pounds, respectively, as a result of expansions at our Geismar, Louisiana facilities in 2025.

(7) Includes production capacity in Lake Charles and Calvert City owned by OpCo and our portion of LACC's production capacity in Lake Charles. For additional information on OpCo, see "Ethylene" below.

(8) Excludes production capacity related to the PVC resin unit owned by the Company's 95% owned joint venture Suzhou Huasu Plastics, which was closed in October 2025.

(9) Except as noted in notes (10) and (11) below, we own each of these facilities.

(10) We lease the land on which our Gendorf, Burghausen, Knapsack, Cologne and Esslingen, Germany facilities, Longview and Deer Park, Texas facilities and Argo, Illinois facility are located. We also lease the Esslingen, Germany building.

(11) We lease a portion of the land on which our Calvert City facility is located.

Ethylene. Ethylene is the world's most widely used petrochemical in terms of volume. It is the key building block used to produce a large number of higher value-added chemicals including PE, EDC, and VCM. We are party to certain agreements with Westlake Partners and OpCo whereby, among other things, OpCo sells us 95% of the ethylene it produces on a cost-plus basis that is expected to generate a fixed margin per pound of $0.10. OpCo has the capacity to produce approximately 3.0 billion pounds of ethylene per year at our Lake Charles site, and we have the capability to consume all of OpCo's production that we purchase at Lake Charles to produce EDC, VCM, and polyethylene. In addition, we (through OpCo) produce ethylene co-products including chemical grade propylene, crude butadiene, pyrolysis gasoline and hydrogen. We (through OpCo) sell our entire output of these co-products to external customers. The ethylene from OpCo's facility in Calvert City and LACC's facility in Lake Charles is used to produce VCM at our facilities. We obtain the remainder of the ethylene we need for our business from third party purchases. The use of ethane feedstock by our ethylene plants enables us to enhance our low-cost materials chain integration.

Chlorine and Caustic Soda. We are one of the largest producers of chlor-alkali in the world, having the capacity to produce approximately 6.7 billion pounds of chlorine and 7.5 billion pounds of caustic soda. We combine salt and electricity to produce chlorine and caustic soda, commonly referred to as chlor-alkali, at our Lake Charles, Plaquemine, Natrium, Calvert City, Geismar, Beauharnois, Longview (Washington), Gendorf, Knapsack and Kaohsiung facilities. Our Lake Charles, Plaquemine and Natrium cogeneration assets have the capacity to generate approximately 790, 240 and 100 megawatts of electricity, respectively, per year. We use our chlorine production in our VCM and chlorinated derivative products plants. We currently have the capacity to supply all of our chlorine requirements internally. Any remaining chlorine is sold into the merchant chlorine market. Our caustic soda is sold to external customers who use it for, among other things, to produce pulp and paper, organic and inorganic chemicals and alumina.

VCM. VCM is used to produce PVC, solvents and PVC-related products. We use ethylene and chlorine to produce EDC, which is used in turn, to produce VCM. We have the capacity to produce approximately 6.1 billion pounds and 1.6 billion pounds of VCM per year at our North American and European facilities, respectively. The majority of our VCM is used internally in our PVC operations. VCM and EDC not used internally are sold externally.

PVC. PVC, the world's third most widely used plastic, is an attractive alternative to traditional materials such as glass, metal, wood, concrete and other plastic materials because of its versatility, durability and cost-competitiveness. PVC is produced from VCM, which is, in turn, made from chlorine and ethylene.

We are one of the largest PVC producers in the world. We have the capacity to produce approximately 5.5 billion pounds and 1.0 billion pounds of commodity and specialty PVC per year, respectively, at our various facilities globally. We use some of our PVC internally in the HIP segment for the production of our building products, pipe and fittings and compounds. The remainder of our PVC is sold to downstream fabricators and the international markets.

Polyethylene. Polyethylene, the world's most widely consumed polymer, is used to manufacture a wide variety of film, coatings and molded product applications primarily used in packaging. PE is generally classified as either LDPE, LLDPE or high-density polyethylene ("HDPE"). The density correlates to the relative stiffness of the end-use products. The difference between LDPE and LLDPE is molecular, and products produced from LLDPE, in general, have higher strength properties than products produced from LDPE. LDPE exhibits better clarity and other physical properties and is used in end products such as bread bags, food wraps, milk carton coatings and food packaging. LLDPE is used for higher film strength applications such as stretch film and heavy-duty sacks. HDPE is used to manufacture products such as groceries, merchandise and trash bags, rigid plastic containers, plastic closures and pipes.

We are a leading producer of LDPE by capacity in North America and predominantly use the autoclave technology (versus tubular technology), which is capable of producing higher-margin specialty PE products. In 2025, our annual capacity of approximately 1.5 billion pounds of LDPE was available in numerous formulations to meet the needs of our diverse customer base. We also have the capacity to produce approximately 1.1 billion pounds of LLDPE per year in various formulations. We produce LDPE and LLDPE at both the Lake Charles and Longview (Texas) facilities. Our Lake Charles and Longview facilities also have the capability to produce HDPE. We sell PE to external customers as a final product in pellet form.

Chlorinated Derivative Materials. Our chlorinated derivative products include ethyl chloride, perchloroethylene, trichloroethylene, tri-ethane® solvents, VersaTRANS® solvents, calcium hypochlorite, hydrochloric acid (HCL) and pelletized caustic soda. We have the capacity to produce approximately 2.3 billion pounds of chlorinated derivative products per year, primarily at our Lake Charles, Natrium, Beauharnois and Longview (Washington) facilities. The majority of our chlorinated derivative products are sold to external customers who use these products for, among other things, refrigerants, water treatment applications, chemicals and pharmaceutical production, food processing, steel pickling, solvent and cleaning chemicals and natural gas and oil production.

Epoxy Specialty Resins. We are one of the leading producers of epoxy specialty resins, modifiers and curing agents in Europe, the United States and Asia with a global reach to our end markets. Epoxy resins are the fundamental component of many types of materials and are often used in the automotive, construction, wind energy, aerospace and electronics industries due to their superior adhesion, strength and durability. Epoxy specialty resins are used for a variety of high-end coating applications that require superior adhesion, corrosion resistance and durability of epoxy such as protective coatings that are used for construction, flooring and transportation, among others. We produce epoxy specialty resins at our plants located in Duisburg and Esslingen, Germany, Barbastro, Spain, Onsan, South Korea, and Lakeland, Florida and Argo, Illinois in the United States. We have the total capacity to produce approximately 580 million pounds of epoxy specialty resins per year, all of which is sold to external customers.

Base Epoxy Resins and Intermediaries (BERI). We are a leading supplier of Liquid and Solid Epoxy Resin. These base epoxies are used in a wide variety of industrial coatings applications. In addition, we are a major producer of bisphenol-A ("BPA"), a key precursor in the downstream manufacturing of basic epoxy resins and specialty resins. We internally consume the majority of our BPA, which ensures consistent supply of our required intermediate materials. We produce base epoxies and intermediaries at our Deer Park, Texas facility, where we have the capacity to produce approximately 610 million pounds per year.

Product and Application Development. Our product and application development activities are geared towards developing and enhancing products, processes and applications. Facilities where we perform such activities are located in the United States, Germany and China.

Feedstocks

We are highly integrated along our materials production chain. We (through OpCo) produce most of the ethylene required to produce our PE and vinyl products. Ethylene can be produced from either petroleum liquid feedstocks, such as naphtha, condensates and gas oils, or from natural gas liquid feedstocks, such as ethane, propane and butane. Both of OpCo's Lake Charles ethylene plants use ethane as the primary feedstock. Pursuant to a feedstock supply agreement between us and OpCo, OpCo receives ethane feedstock at our Lake Charles site through several pipelines from a variety of suppliers in Texas and Louisiana. We own a 50% interest in a 104-mile natural gas liquids pipeline from Mont Belvieu to our Lake Charles facility. OpCo owns a 200-mile ethylene pipeline that runs from Mont Belvieu to our Longview (Texas) site. Additionally, through OpCo, we produce most of the ethylene required at our Calvert City facility utilizing ethane feedstock. The LACC ethylene facility is located adjacent to our chlor-alkali facility in Lake Charles and has an ethylene production capacity of 2.2 billion pounds per year. At December 31, 2025, we, through one of our subsidiaries, owned 50% of the membership interests in LACC. We receive our proportionate share in ethylene production on a cash-cost basis and primarily use it to produce VCM. In Germany, we have access to, and partially own, an ethylene pipeline.

We acquire butene and hexene to manufacture PE. We receive butene and hexene at the Lake Charles site and hexene at the Longview (Texas) site by rail car from several suppliers. We purchase butene and hexene pursuant to multi-year contracts.

The salt requirements for several of our larger chlor-alkali plants are supplied internally from salt domes we either own or lease and the salt-water brine is transported by pipelines we own. We purchase the salt required for our other chlor-alkali plants pursuant to long-term contracts. Electricity and steam for one of our Lake Charles facilities and our Plaquemine facility are produced by on-site cogeneration units. A portion of our Natrium facility's electricity requirements is produced by our on-site generation unit, and the remainder is purchased. We purchase electricity for our remaining facilities under long-term contracts. We purchase VCM for our Asian PVC plant on a contract and spot basis.

The raw materials used to manufacture our epoxy products include chlorine, caustic soda, phenol and acetone, all of which are available from more than one source. Prices for our main feedstocks are generally driven by the underlying petrochemical benchmark prices and energy costs, which are subject to price fluctuations.

Marketing, Sales and Distribution

We have a dedicated sales force for our business, organized by product line and region that sells our products directly to our customers. In addition, we rely on distributors to market products to smaller customers. Our PE customers are some of the nation's largest producers of film and flexible packaging. We and OpCo sell ethylene and ethylene co-products to external customers. OpCo's primary ethylene co-products are chemical grade propylene, crude butadiene, pyrolysis gasoline and hydrogen. We have storage agreements and exchange agreements that provide us and OpCo with access to customers who are not directly connected to the pipeline system that we own. OpCo ships crude butadiene and pyrolysis gasoline by rail or truck. Additionally, we transport our polyethylene by rail or truck.

We use some of our PVC internally to produce our building products, pipe and fittings and compounds in the HIP segment. The remainder of our PVC is sold to downstream fabricators and the international markets. We have the capacity to use a majority of our chlorine internally to produce VCM and EDC, most of which, in turn, is used to produce PVC. We also use our chlorine internally to produce chlorinated derivative products. We sell the remainder of our chlorine and substantially all of our caustic soda production to external customers. The majority of our products are shipped from production facilities directly to the customer via pipeline, truck, rail, barge and/or ship. The remaining products are shipped from production facilities to third party chemical terminals and warehouses until being sold to customers.

No single customer accounted for 10% or more of net sales for the PEM segment in 2025.

Competition

The markets in which our PEM businesses operate are highly competitive, with competition based primarily on price and to a lesser extent, on product availability, product quality and consistency, product performance and customer service. We sell our commodities products in global markets, with prices related to the balance of supply and demand, which is affected by production and exports from other countries. As such, our competitive position is affected by trade regulations, international fair trade laws, policies and disputes, trade barriers, tariffs, duties or other taxes.

Our competitors in the ethylene and PE markets are some of the world's largest chemical companies, including Chevron Phillips Chemical Company, Dow Inc., ExxonMobil Chemical Company, Formosa Plastics Corporation, LyondellBasell Industries, N.V., NOVA Chemicals Corporation and Sasol Limited. We compete in the chlor-alkali and PVC markets with other producers including Formosa Plastics Corporation, INOVYN ChlorVinyls Limited, KEM ONE Group SAS, Olin Corporation, Orbia Advance Corporation, Occidental Chemical Corporation, Shintech, Inc. and VYNOVA Group. Our competitors in the epoxy value chain include Olin Corporation, Nan Ya Plastics Corporation, the Spolchemie Group, LEUNA-Harze GmbH, Aditya Birla Chemicals (Thailand) Ltd., Huntsman Corporation, Swancor Holding Company Limited, Ningbo Bohui Chemical Technology Co., Ltd., Techstorm Advanced Material Co., Ltd., Shanghai Kangda Chemical New Material Group Co., Ltd., Evonik Industries AG, Allnex Management GmbH, Kukdo Chemical Co., Ltd., Kumhu Asiana Group and Chang Chun Plastics Co., Ltd.

Seasonality

Our sales of chlorovinyls products have historically experienced some seasonality. We have typically experienced moderately higher levels of sales of our PEM products in the first half of the year and lower levels in the fourth quarter coinciding with the seasonal trends of our HIP business. The chlor-alkali and petrochemical industries in general exhibit cyclical commodity characteristics influenced by changes in the balance between global supply and demand and the resulting operating rates, the level of general economic activity, turnaround activities and the price of raw materials.

Environmental

As is common in our industry, we are subject to environmental laws and regulations related to the use, storage, handling, generation, transportation, emission, discharge, disposal and remediation of, and exposure to, hazardous and non-hazardous substances and wastes in all of the countries in which we do business. National, state or provincial and local standards regulating air, water and land quality affect substantially all of our manufacturing locations around the world. Compliance with such laws and regulations has required and will continue to require capital expenditures and increase operating costs.

It is our policy to comply with all environmental, health and safety requirements and to provide safe and environmentally sound workplaces for our employees. In some cases, compliance can be achieved only by incurring capital expenditures. In 2025, we made capital expenditures of $49 million related to environmental compliance. We estimate that we will make capital expenditures of approximately $103 million in 2026 and $125 million in 2027, respectively, related to environmental compliance. The expected 2026 and 2027 capital expenditures are relatively higher than the amounts we have spent related to environmental compliance in recent years in large part due to capital expenditures related to previously existing and new Environmental Protection Agency (the "EPA") regulations, including the EPA's 2024 update to the hazardous organic national emission standards for hazardous air pollutants ("NESHAPs"). The remainder of the 2026 and 2027 estimated expenditures are related to equipment replacement and upgrades. We anticipate that stringent environmental regulations will continue to be imposed on us and the industry in general.

From time to time, we receive notices or inquiries from government entities regarding alleged violations of environmental laws and regulations pertaining to, among other things, the disposal, emission and storage of chemical substances, including hazardous wastes. Pursuant to Item 103 of the SEC's Regulation S-K, the following environmental matters involve a governmental authority as a party to the proceedings and potential monetary sanctions that we believe could exceed $1 million (which is less than one percent of our current assets on a consolidated basis as of December 31, 2025):

•Natrium Facility Discharge Investigation. To resolve alleged violations associated with exceedances of discharge limits under the Natrium facility's National Pollutant Discharge Elimination System ("NPDES") permit effective August 2020, we have entered into enforcement negotiations with the West Virginia Department of Environmental Protection ("WVDEP"). The resolution of this matter may involve a penalty in excess of $1 million.

Also see our discussion of our environmental matters contained in Item 1A, "Risk Factors" below, Item 3, "Legal Proceedings" below and Note 21 "Commitments and Contingencies" to Consolidated Financial Statements included in Item 8 of this Form 10-K.

Human Capital

Westlake is committed to acting in a safe, ethical and environmentally and socially responsible manner. While we have been a public company for 21 years, we still think of our employees as members of our extended family. We value the integrity, creativity, dedication and diversity of ideas that our employees bring to work every day.

Headcount

As of December 31, 2025, we had approximately 14,600 employees in the following areas:

CategoryNumber

Housing and Infrastructure Products segment
7,400

Performance and Essential Materials segment
6,500

Corporate and other
700

Our employees are distributed across 18 countries. As of December 31, 2025, approximately 68% were employed in the United States. Approximately 24% of our employees are represented by labor unions, including works councils in Europe, and our collective bargaining agreements in Europe, North America and Asia expire at various times through 2029. We believe that our relationship with our employees and unions is open and positive.

Attracting, developing and retaining talented people is crucial to executing our strategy and achieving our business goals. Our ability to recruit and retain such talent depends on a number of factors, including compensation and benefits, career opportunities and work environment. We provide our employees with competitive compensation packages, development programs that enable continued learning and growth, and comprehensive and competitive benefit packages. Our global compensation and benefits arrangements generally are tailored to local markets of operation.

Training and Professional Development

As part of our retention and promotion efforts, we invest in internal leadership development. We regularly provide our employees with a blend of live, virtual, and digital training opportunities. Depending on an employee's position and job responsibilities, these opportunities include safety training, technical courses, compliance training relating to company policies, business and professional development training, and professional growth classes. We also periodically conduct employee surveys to gauge employee engagement and identify areas for additional focus.

Culture and Community

Engaging with the communities in which we live and work is important to Westlake, and our employees around the world regularly engage in local community events and organizations. These service opportunities include supporting programs developing interest in science, technology, engineering and mathematics (STEM) and manufacturing careers for children and young adults, improving the environment, supporting veterans, and participating in sporting events raising awareness of various causes that are important to our communities.

Health and Safety

The health and safety of our employees and our operations is our highest priority. Our health and safety programs are designed around global standards with appropriate variations to address multiple jurisdictions and regulations, specific hazards and unique working environments of our manufacturing, research and development, and administrative office locations. We require each of our locations to perform regular safety audits to ensure proper safety policies, program procedures, analyses and training are in place.

Our focus on safety starts with our Board of Directors. Safety is a key performance indicator that is reported on and discussed at every Board meeting. Our Health, Safety and Environment ("HSE") team plays a pivotal role in overseeing all related policy protections, risk identification and other aspects of our business.

Several of our U.S. manufacturing sites have been recognized by the U.S. Occupational Safety & Health Administration's ("OSHA") Voluntary Protection Program for their low injury rates, employee engagement, and safety programs. Several of our manufacturing sites have achieved ISO 45001 certification, which are internationally recognized standards for Occupational Health and Safety.

Intellectual Property and Technology

We rely upon both trademark and service mark protection to protect our brands and intellectual property, and have registered or applied to register many of these on a world-wide basis. We have more than 1,900 active and pending trademark registrations worldwide for our various business segments. We also rely on a combination of patents and un-patented proprietary know-how and trade secrets to preserve our competitive technology position in the market. We have more than 1,100 issued patents and pending-patent applications in the United States and several other countries. While some of our production capacity operates under licenses from third parties, other parts of our production operate under technology that was developed internally. We offer our own independently developed technology for licensing when the opportunity makes sense on a commercial basis. Although we consider our patents, licenses, trademarks and trade secrets in the aggregate to constitute a valuable asset that provides us with a competitive advantage, we do not regard any one of our businesses as being materially dependent upon any single or group of related patents, trademarks, licenses, or trade secrets.

Available Information

Our website address is www.westlake.com. Our website content is available for information purposes only. It should not be relied upon for investment purposes, nor is it incorporated by reference in this Form 10-K. We make available on this website under "Investor Relations/Financials," free of charge, our proxy statements, annual reports on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K and amendments to those materials as soon as reasonably practicable after we electronically file those materials with, or furnish those materials to, the SEC. The SEC also maintains a website at www.sec.gov that contains reports, proxy statements and other information regarding SEC registrants, including us.

We intend to satisfy the requirement under Item 5.05 of Form 8-K to disclose any amendments to our Code of Ethics and any waiver from a provision of our Code of Ethics by posting such information on our website at www.westlake.com under "Investor Relations/Governance."