v3.26.1
Schedule H, Line 4i – Schedule of Assets (Held At End of Year)
 12 Months Ended
Dec. 31, 2025
EBP 003  
EBP, Schedule of Asset Held for Investment [Line Items]  
Schedule H, Line 4i – Schedule of Assets (Held At End of Year)
ECOVYST 401(K) SAVINGS PLAN
Schedule H, Line 4i - Schedule of Assets (Held at End of Year)

EIN 86-2551862, Plan Number 003
December 31, 2025
(a)(b) Identity of issue, borrower, lessor, or similar party(c) Description of investment including maturity date, rate of interest, collateral, par, or maturity value(d) Cost(e) Current
Value
*The Vanguard GroupVanguard Institutional Index Fund Inst'l Sharesa$33,031,544 
*The Vanguard GroupVanguard PRIMECAP Fund Admiral Sharesa32,067,409 
*The Vanguard GroupVanguard Target Retirement 2030 Funda16,827,078 
*The Vanguard GroupVanguard Total Bond Market Index Fund: Inst'l Shra15,922,855 
*The Vanguard GroupVanguard Target Retirement 2035 Funda15,716,107 
*The Vanguard GroupVanguard Target Retirement 2025 Funda15,462,144 
*The Vanguard GroupVanguard Total Stock Market Index Fund: Inst'l Shra13,828,623 
*The Vanguard GroupVanguard Target Retirement 2045 Funda12,361,330 
*The Vanguard GroupVanguard Target Retirement 2040 Funda12,015,248 
*The Vanguard GroupVanguard Total International Stock Index Fund: Inst'l Shra11,689,867 
*The Vanguard GroupVanguard Wellington Fund Admiral Sharesa11,121,700 
*The Vanguard GroupVanguard Cash Reserves Federal MM Fund Admiral Sharesa10,745,014 
*The Vanguard GroupVanguard Windsor II Fund Admiral Sharesa10,122,637 
*The Vanguard GroupVanguard Target Retirement 2050 Funda9,340,928 
*The Vanguard GroupVanguard U.S. Growth Fund Investor Sharesa8,519,787 
*The Vanguard GroupVanguard Target Retirement 2020 Funda7,443,503 
*The Vanguard GroupVanguard Target Retirement 2055 Funda6,677,518 
*The Vanguard GroupVanguard Mid-Cap Index Fund Investor Sharesa5,939,888 
*The Vanguard GroupVanguard Target Retirement Incomea5,712,944 
*The Vanguard GroupVanguard Small-Cap Index Fund Investor Sharesa4,703,783 
*The Vanguard GroupVanguard Wellesley Income Fund Investor Sharesa4,669,505 
*The Vanguard GroupVanguard International Growth Fund Investor Sharesa4,178,031 
*The Vanguard GroupVanguard Explorer Fund Investor Sharesa3,592,111 
*The Vanguard GroupVanguard Target Retirement 2060 Funda3,292,320 
PIMCOPIMCO Total Return Fund, Administrative Classa1,755,622 
Fidelity InvestmentsFidelity Value Fund; Retail Classa1,582,243 
*The Vanguard GroupVanguard Target Retirement 2065 Funda869,934 
*Ecovyst Inc.Ecovyst Stock Funda323,303 
*The Vanguard GroupVanguard Target Retirement 2070 Funda32,098 
*Notes receivable from participants
Interest rates from 4.25% to 9.50%
—3,413,165 
Total$282,958,239 
* - Indicates a party-in-interest to the Plan
a - The cost of participant directed investments is not required to be disclosed