As Of	Filer	Filing¹	For·On·As	Docs:Size	Issuer		Filing Agent

  5/9/24  Ecovyst Inc.                      8-K:5,8,9    5/8/24   11:170K                                   Donnelley … Solutions/FA 
  5/9/24  Ecovyst Inc.                      8-K/A:5     2/22/24   10:135K                                   Donnelley … Solutions/FA 
  5/6/24  Ecovyst Inc.                      DEFA14A                1:25K                                    Donnelley … Solutions/FA 
  5/6/24  Ecovyst Inc.                      8-K:5        5/3/24   10:134K                                   Donnelley … Solutions/FA 
  5/3/24  Ecovyst Inc.                      10-Q        3/31/24   97:7.3M                                                            
  5/2/24  Ecovyst Inc.                      8-K:2,9      5/2/24   11:707K                                                            
  4/8/24  Ecovyst Inc.                      ARS        12/31/23    1:11M                                    Broadridge Fin’l So… Inc 
  4/8/24  Ecovyst Inc.                      DEF 14A      5/8/24   11:18M                                    Broadridge Fin’l So… Inc 
 3/26/24  Ward Susan F                      4          Director²   1:5K   Ecovyst Inc.                      Ecovyst Inc.             
 3/22/24  Ward Susan F                      144                    1:5K   Ecovyst Inc.                      E TRADE Fin’l… Office/FA 
 3/15/24  Ecovyst Inc.                      PRE 14A      5/8/24   12:11M                                    Broadridge Fin’l So… Inc 
 3/12/24  Lorance Sarah                     4          Director²   1:4K   Ecovyst Inc.                      Ecovyst Inc.             
  3/8/24  Lorance Sarah                     3          Director²   2:348K Ecovyst Inc.                      Ecovyst Inc.             
 2/29/24  Ecovyst Inc.                      10-K       12/31/23  167:20M                                                             
 2/28/24  Ecovyst Inc.                      8-K:5,8     2/22/24   10:140K                                   Donnelley … Solutions/FA 
 2/28/24  Ecovyst Inc.                      8-K:2,9     2/28/24   11:889K                                                            
 2/13/24  Vanguard Group Inc.               SC 13G/A               1:13K  Ecovyst Inc.                      Toppan Merrill/FA        
 2/13/24  Hotchkis & Wiley Capital Mgmt LLC SC 13G                 1:53K  Ecovyst Inc.                      Adviser Compliance … LLC 
 2/12/24  CCMP Capital Investors III, L.P.  SC 13G/A               1:202K Ecovyst Inc.                      Donnelley … Solutions/FA 
          CCMP Capital Associates III GP, LLC³
          CCMP Capital Associates III, L.P.³
          CCMP Capital GP, LLC³
          CCMP Capital Investors III (Av-10), L.P.³
          CCMP Capital Investors III (Av-7), L.P.³
          CCMP Capital Investors III (Av-8), L.P.³
          CCMP Capital Investors III (Av-9), L.P.³
          CCMP Capital Investors III (Employee), L.P.³
          CCMP Capital, LP³
          CCMP Co-Invest III A GP, LLC³
          Quartz Co-Invest, L.P.³
  2/9/24  Dimensional Fund Advisors LP      SC 13G                 1:17K  Ecovyst Inc.                                               

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¹	Filing/Form Types:
	3	Initial Statement of Beneficial Ownership of Securities by an Insider — Form 3 { The Filer is an Insider² of the Issuer }.
	4	Statement of Changes in Beneficial Ownership of Securities by an Insider — Form 4 { The Filer is an Insider² of the Issuer }.
	8-K	Current Report — Form 8-K { Item 1: Business & Operations;  2: Financial Info;  3: Securities & Trading;  4: Accountants & Accounting;  5: Governance & Management;  6: Asset-Backed Securities;  7: Disclosures;  8: Events;  9: Financials }.
	10-K	Annual Report — Form 10-K.
	10-Q	Quarterly Report — Form 10-Q.
	144	Notice of a Proposed Sale of Securities by an Insider — Form 144 { The Filer is an Insider² of the Issuer }.
	ARS	Annual Report to Security Holders.
	DEF 14A	Definitive Proxy Statement — Schedule 14A.
	DEFA14A	Definitive Additional Proxy Soliciting Material — Schedule 14A.
	PRE 14A	Preliminary Proxy Statement — Schedule 14A.
	SC 13G	Statement of Acquisition of Beneficial Ownership by a “Passive” Investor — Schedule 13G.
	/A	Amendment to, or Amended version of, a previous Filing of this Type.
²	Insider:  The Filer is a Director, Officer, 10% Owner and/or Other “insider” of the Issuer.
³	Group Member:  A Registrant or non-Registrant party to this Filing made by a Group.