Ecovyst Inc. (NYSE: ECVT) shares plummeted 9.18% in pre-market trading on Tuesday after the company reported disappointing third-quarter results and lowered its full-year 2025 guidance. The provider of virgin sulfuric acid and sulfuric acid regeneration services faced headwinds from unplanned customer downtime and lower regeneration volumes.

For the third quarter, Ecovyst reported sales of $204.9 million, missing the analyst consensus estimate of $219.2 million. The company's adjusted EBITDA came in at $57.5 million, falling short of the expected $67 million. Despite beating adjusted EPS estimates at $0.19 per share, Ecovyst posted a net loss from continuing operations of $2.4 million for the first nine months of 2025, compared to net income of $22.4 million in the same period last year.

Adding to investor concerns, Ecovyst lowered its 2025 sales guidance for continuing operations to a range of $700 million to $740 million, down from its previous outlook of $795 million to $835 million. The company now expects 2025 adjusted EBITDA of approximately $170 million. The reduced guidance and missed estimates, coupled with ongoing restructuring efforts including the planned divestiture of its Advanced Materials & Catalysts segment, have likely contributed to the sharp stock price decline.