Form 4 Filing for Ecovyst Inc.

This filing details a transaction by Patti A. Humble, a director at Ecovyst Inc. On September 10, 2026, Ms. Humble acquired 24,875 shares of Common Stock at a price of $10.05 per share. Following this transaction, her total ownership of the company's stock amounts to 33,974 shares. The transaction was made directly, as indicated by the ownership nature code "D". The filing was signed on September 14, 2026, by Joseph S. Koscinski, acting as attorney-in-fact for Ms. Humble.