X0306 4 2022-05-05 0 0001708035 Ecovyst Inc. ECVT 0001478560 Fogarty Kevin Michael C/O ECOVYST INC. 300 LINDENWOOD DRIVE MALVERN PA 19355 1 0 0 0 Common Stock 2022-05-05 4 P 0 40000 9.8532 A 40000 I GBBH Family Limited Partnership Common Stock 39800 D The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $9.68 to $9.98, inclusive. The reporting person undertakes to provide to Ecovyst Inc., any security holder of Ecovyst Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in footnote (1) to this Form 4. /s/ Joseph S. Koscinski, as attorney-in-fact for Kevin M Fogarty 2022-05-09