Sixth Consecutive Year of Recognition

PITTSBURGH, Dec. 16, 2025 /PRNewswire/ -- Koppers Holdings Inc. (NYSE:KOP), an integrated global provider of treated wood products, wood treatment chemicals and carbon compounds, has been named as one of America's Most Responsible Companies by Newsweek magazine for the sixth consecutive year for 2026. 

"We are honored to once again be named among America's Most Responsible Companies – a reflection of our employees' unwavering commitment to living out our values of People, Planet and Performance," said Stephanie Apostolou, Chief Legal and Sustainability Officer and Secretary. "Looking ahead we will continue to integrate Sustainability with our long-term business strategy as we work to advance infrastructure through safer, stronger, more sustainable solutions."

Notable results from Koppers most recent Corporate Sustainability Report (2024) include:

• 2.52 total recordable injury rate, the lowest in company history.
• 53% increase in solar energy production year-over-year.
• 27% of energy consumed being produced from renewable sources.
• 38% of timber purchases in the Utility and Industrial Products business were sustainably certified, the highest on record.
• 81% of employees reported being happy working at Koppers, the highest score since 2018.

Top companies are selected from the 2,000 largest publicly traded companies headquartered in the U.S., with scores based on quantitative research, including more than 30 key performance indicators in the areas of environmental, social and corporate governance, as well as a large-scale public perception survey.

The full America's Most Responsible Companies list for 2026 can be viewed here. To learn more about Koppers Sustainability reporting, click here.

About Koppers

Koppers (NYSE:KOP) is an integrated global provider of essential treated wood products, wood preservation technologies and carbon compounds. Our team of 1,850 employees create, protect and preserve key elements of our global infrastructure – including railroad crossties, utility poles, outdoor wooden structures, and production feedstocks for steel, aluminum and construction materials, among others – applying decades of industry-leading expertise while constantly innovating to anticipate the needs of tomorrow. Together we are providing safe and sustainable solutions to enable rail transportation, keep power flowing, and create spaces of enjoyment for people everywhere. Protecting What Matters, Preserving The Future. Learn more at Koppers.com.

Safe Harbor Statement 

Certain statements in this press release are "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995 and may include, but are not limited to, statements about sales levels, acquisitions, restructuring, declines in the value of Koppers assets and the effect of any related impairment charges, profitability and anticipated expenses and cash outflows. All forward-looking statements involve risks and uncertainties.

All statements contained herein that are not clearly historical in nature are forward-looking, and words such as "outlook," "guidance," "forecast," "believe," "anticipate," "expect," "estimate," "may," "will," "should," "continue," "plan," "potential," "intend," "likely," or other similar words or phrases are generally intended to identify forward-looking statements. Any forward-looking statement contained herein, in other press releases, written statements or other documents filed with the Securities and Exchange Commission, or in Koppers communications and discussions with investors and analysts in the normal course of business through meetings, phone calls and conference calls, regarding future dividends, expectations with respect to sales, earnings, cash flows, operating efficiencies, restructurings, cost reduction efforts, transformation initiatives, product introductions or expansions, the benefits of acquisitions, divestitures, joint ventures or other matters as well as financings and debt reduction, are subject to known and unknown risks, uncertainties and contingencies.

Many of these risks, uncertainties and contingencies are beyond our control, and may cause actual results, performance or achievements to differ materially from anticipated results, performance or achievements. Factors that might affect such forward-looking statements include, among other things, availability of and fluctuations in the prices of key raw materials, including coal tar, lumber and scrap copper; the impact of changes in commodity prices, such as oil, copper and chemicals, on product margins; the successful implementation of multi-year cost mitigation programs; the extent of the dependence of certain of our businesses on certain market sectors and customers; economic, political and environmental conditions in international markets, including governmental changes, tariffs, restrictions on trade and restrictions on the ability to transfer capital across countries; current and potential future tariffs or duties; general economic and business conditions; potential difficulties in protecting our intellectual property; the ratings on our debt and our ability to repay or refinance our outstanding indebtedness as it matures; our ability to operate within the limitations of our debt covenants; unexpected business disruptions; potential delays in timing or changes to expected benefits from cost reduction efforts; timing and results of any transformation initiatives, including estimates and assumptions related to the cost and the anticipated benefits of the transformation initiatives; potential impairment of our goodwill and/or long-lived assets; demand for Koppers goods and services; competitive conditions; capital market conditions, including interest rates, borrowing costs and foreign currency rate fluctuations; disruptions and inefficiencies in the supply chain; changes in laws; the impact of environmental laws and regulations and compliance therewith; unfavorable resolution of claims against us, as well as those discussed more fully elsewhere in this release and in documents filed with the Securities and Exchange Commission by Koppers, particularly our latest annual report on Form 10-K and any subsequent filings by Koppers with the Securities and Exchange Commission. We caution you that the foregoing list of important factors may not contain all of the material factors that are important to you. In addition, in light of these risks and uncertainties, the matters referred to in the forward-looking statements contained in this release may not in fact occur. Any forward-looking statements in this release speak only as of the date of this release, and we undertake no obligation to update any forward-looking statement to reflect events or circumstances after that date or to reflect the occurrence of unanticipated events.

Media Contact:

Jessica Black, Senior Manager, Corporate Communications

412 227 2025

BlackJF@koppers.com

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SOURCE KOPPERS HOLDINGS INC.