X0306 4 2022-01-17 0 0001708035 Ecovyst Inc. ECVT 0001717989 Sichko William J. Jr. C/O ECOVYST INC. 300 LINDENWOOD DRIVE MALVERN PA 19355 0 1 0 0 See Remarks Common Stock 2022-01-17 4 A 0 72887 0.00 A 356250 D Common Stock 2022-01-17 4 A 0 97182 0.00 A 453432 D Common Stock 585042 I By family trust Represents shares of common stock held by a family trust. Mr. Sichko disclaims beneficial ownership of such securities except to the extent of his pecuniary interest therein, and the filing of this report is not an admission that Mr. Sichko is the beneficial owner of such securities for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose. Vice President, Chief Administrative Officer /s/ Joseph S. Koscinski, as attorney-in-fact for William J. Sichko Jr. 2022-01-19