# EDGAR Filing Document

**Accession Number:** 0001708035
**File Stem:** 0001193125-25-317640
**Filing Date:** 2025-12
**Character Count:** 5200
**Document Hash:** 4d556fbc0641c26c9f3579256cd7cd77
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-25-317640.hdr.sgml**: 20251212

**ACCESSION NUMBER**: 0001193125-25-317640

**CONFORMED SUBMISSION TYPE**: 8-K

**PUBLIC DOCUMENT COUNT**: 12

**CONFORMED PERIOD OF REPORT**: 20251208

**ITEM INFORMATION**: Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers: Compensatory Arrangements of Certain Officers

**FILED AS OF DATE**: 20251212

**DATE AS OF CHANGE**: 20251212

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Ecovyst Inc.
- **CENTRAL INDEX KEY:** 0001708035
- **STANDARD INDUSTRIAL CLASSIFICATION:** CHEMICALS & ALLIED PRODUCTS [2800]
- **ORGANIZATION NAME:** 08 Industrial Applications and Services
- **EIN:** 813406833
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 8-K
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-38221
- **FILM NUMBER:** 251568534

**BUSINESS ADDRESS:**
- **STREET 1:** 600 LEE ROAD, SUITE 200
- **CITY:** WAYNE
- **STATE:** PA
- **ZIP:** 19087
- **BUSINESS PHONE:** 484-617-1200

**MAIL ADDRESS:**
- **STREET 1:** 600 LEE ROAD, SUITE 200
- **CITY:** WAYNE
- **STATE:** PA
- **ZIP:** 19087

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** PQ Group Holdings Inc.
- **DATE OF NAME CHANGE:** 20170531

?xml version='1.0' encoding='ASCII'? 8-K

### UNITED STATES

### SECURITIES AND EXCHANGE COMMISSION

#### Washington, D.C. 20549

### FORM 8-K

#### CURRENT REPORT

#### Pursuant to Section 13 or 15(d)

#### of The Securities Exchange Act of 1934

#### Date of Report (Date of earliest event reported): December 8, 2025

## Ecovyst Inc.
(Exact Name of Registrant as Specified in its Charter)

#### Commission File Number: 001-38221

---

| | |
|:---|:---|
| **Delaware** | **81-3406833** |
| **(State or other jurisdiction of**<br> **incorporation or organization)** | **(I.R.S. Employer<br>Identification No.)** |
| **600 Lee Road, Suite 200** |  |
| **Wayne, Pennsylvania** | **19087** |
| **(Address of principal executive offices)** | **(Zip Code)** |

---

---

| |
|:---|
| **(484) 617-1200** |
| **(Registrant's telephone number, including area code)** |

---

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

#### Securities registered pursuant to Section 12(b) of the Act:

---

| | | |
|:---|:---|:---|
| **Title of each class** | **Trading<br>symbol** | **Name of each exchange<br>on which registered** |
| Common stock, par value $0.01 per share | ECVT | New York Stock Exchange |

---

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

------

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| | |
|:---|:---|
| **Item 5.02** | **Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.**  |

---

On December 8, 2025, the Compensation Committee (the "Committee") of the Board of Directors of Ecovyst Inc. (the "Company") approved a supplemental bonus grant to Paul Whittleston, the Company's Vice President and President – Advanced Materials & Catalysts ("AM&C"), pursuant to the retention bonus program previously adopted by the Committee on December 9, 2024 and under which certain employees of the Company, including Mr. Whittleston, were granted retention bonuses tied to certain outcomes of the strategic review process relating to the AM&C business. Pursuant to this supplemental bonus award, Mr. Whittleston would be entitled to an amount equal to three months of his base salary, payable following a successful consummation of the Company's previously announced agreement to sell the AM&C business to Technip Energies N.V., in addition to the amounts already granted to Mr. Whittleston pursuant to the retention bonus program approved by the Committee on December 9, 2024.

------

#### SIGNATURE
Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

---

| | | |
|:---|:---|:---|
| Date: December 12, 2025 | **Ecovyst Inc.** | **Ecovyst Inc.** |
|  | By: | /s/ Joseph S. Koscinski |
|  | Name: | Joseph S. Koscinski |
|  | Title: | Vice President, Chief Administrative Officer, General Counsel and Secretary |

---