# EDGAR Filing Document

**Accession Number:** 0000003197
**File Stem:** 0001193125-26-255977
**Filing Date:** 2026-6
**Character Count:** 8891
**Document Hash:** 3732ea4341c21577ccef2e163a82903d
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-26-255977.hdr.sgml**: 20260603

**ACCESSION NUMBER**: 0001193125-26-255977

**CONFORMED SUBMISSION TYPE**: 4

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20260601

**FILED AS OF DATE**: 20260603

**DATE AS OF CHANGE**: 20260603

**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Harris-Peterson Candace
- **CENTRAL INDEX KEY:** 0001777558

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 000-07099
- **FILM NUMBER:** 261062664

**MAIL ADDRESS:**
- **STREET 1:** 7171 SOUTHWEST PARKWAY
- **STREET 2:** BUILDING 300, SUITE 200
- **CITY:** AUSTIN
- **STATE:** TX
- **ZIP:** 78735
**ISSUER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** CECO ENVIRONMENTAL CORP
- **CENTRAL INDEX KEY:** 0000003197
- **STANDARD INDUSTRIAL CLASSIFICATION:** INDUSTRIAL & COMMERCIAL FANS & BLOWERS & AIR PURIFYING EQUIP [3564]
- **ORGANIZATION NAME:** 06 Technology
- **EIN:** 132566064
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**BUSINESS ADDRESS:**
- **STREET 1:** 5080 SPECTRUM DRIVE
- **STREET 2:** SUITE 800E
- **CITY:** ADDISON
- **STATE:** TX
- **ZIP:** 75001
- **BUSINESS PHONE:** (513) 458-2600

**MAIL ADDRESS:**
- **STREET 1:** 5080 SPECTRUM DRIVE
- **STREET 2:** SUITE 800E
- **CITY:** ADDISON
- **STATE:** TX
- **ZIP:** 75001

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** API ENTERPRISES INC
- **DATE OF NAME CHANGE:** 19920703

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** ALARM PRODUCTS INTERNATIONAL INC
- **DATE OF NAME CHANGE:** 19851210

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## FORM 4

### STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

[ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

[ ] Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>Harris-Peterson Candace<br><sub>(Last) (First) (Middle)</sub><br>5080 SPECTRUM DRIVE<br>SUITE 800E<br><sub>(Street)</sub><br>ADDISON, TX 75001<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2026-06-01 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director [ ] 10% Owner<br>[X] Officer (give title below) [ ] Other (specify below)<br>_Chief Human Resources Officer_ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>CECO ENVIRONMENTAL CORP [ CECO ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[X] Form filed by One Reporting Person<br>[ ] Form filed by More than One Reporting Person |

---

## Table I - Non-Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | 3. Transaction Code (V) | 3. Transaction Code (V) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | Code | V | Amount | (A) or (D) | Price | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| Common Stock | 2026-06-01 |  | A |  | 3133<sup>(3)</sup> | A | <sup>(1)(2)</sup> | 3133 | D |  |
| Common Stock | 2026-06-01 |  | A |  | 2735<sup>(4)</sup> | A | <sup>(1)(2)</sup> | 5868 | D |  |
| Common Stock | 2026-06-01 |  | A |  | 6313<sup>(5)</sup> | A | <sup>(1)(2)</sup> | 12181 | D |  |
| Common Stock | 2026-06-01 |  | A |  | 1401<sup>(6)</sup> | A | <sup>(1)(2)</sup> | 13582 | D |  |
| Common Stock | 2026-06-01 |  | A |  | 4679<sup>(7)</sup> | A | <sup>(1)(2)</sup> | 18261 | D |  |
| Common Stock | 2026-06-01 |  | A |  | 625<sup>(8)</sup> | A | <sup>(1)(2)</sup> | 18886 | D |  |

---

## Table II - Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | 4. Transaction Code (V) | 4. Transaction Code (V) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 6. Date Exercisable and Expiration Date | 6. Date Exercisable and Expiration Date | 7. Title and Amount of Underlying Securities | 7. Title and Amount of Underlying Securities | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | Code | V | (A) | (D) | Date Exercisable | Expiration Date | Title | Amount or Number of Shares | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

---

### Footnotes:

(1) On June 1, 2026 (the "Closing Date"), pursuant to an Agreement and Plan of Merger, dated as of February 23, 2026 (the "Merger Agreement"), by and among CECO Environmental Corp. (the "Issuer"), Thermon Group Holdings, Inc. ("Thermon"), Longhorn Merger Sub, Inc. ("Merger Sub, Inc.") and Longhorn Merger Sub LLC ("Merger Sub LLC"), (i) Merger Sub, Inc. merged with and into Thermon, with Thermon continuing as a wholly-owned subsidiary of the Issuer and the surviving corporation of the merger (the "First Merger") and (ii) Thermon, as the surviving corporation of the First Merger, merged with and into Merger Sub LLC, with Merger Sub LLC being the surviving entity of the merger.

(2) (Continued from Footnote 1) Pursuant to the Merger Agreement, at the effective time of the First Merger (the "Effective Time"), each outstanding restricted stock unit of Thermon (each a "Thermon RSU") and outstanding award of performance units (each a "Thermon PU"), was automatically assumed by the Issuer and converted into a restricted stock unit with respect to a number of shares of the Issuer's common stock equal to the product of (x) the number of shares of Thermon's common stock subject to such Thermon RSU or Thermon PU and (y) 0.8110 (each, a "Converted RSU Award").

(3) On May 12, 2026, the Reporting Person was granted an award of Thermon RSUs, which was assumed and converted into a Converted RSU Award that vests in equal installments on each of June 1, 2027, June 1, 2028 and June 1, 2029.

(4) On June 1, 2025, the Reporting Person was granted an award of Thermon RSUs, which was assumed and converted into a Converted RSU Award that vested as to one-third on June 1, 2026 and vests as to one-third on each of June 1, 2027 and June 1, 2028.

(5) On June 1, 2025, the Reporting Person was granted an award of Thermon PUs, which was assumed and converted into a Converted RSU Award that vests in full on March 31, 2028.

(6) On June 1, 2024, the Reporting Person was granted an award of Thermon RSUs, which was assumed and converted into a Converted RSU Award that vested as to one-half on June 1, 2026 and vests as to one-half on June 1, 2027.

(7) On June 1, 2024, the Reporting Person was granted an award of Thermon PUs, which was assumed and converted into a Converted RSU Award that vests in full on March 31, 2027.

(8) On June 1, 2023, the Reporting Person was granted an award of Thermon RSUs, which was assumed and converted into a fully vested Converted RSU Award.

**Signature:** /s/ Kiril Kovachev as Attorney-in-Fact for Candace Harris-Peterson  
**Date:** 2026-06-03

### Remarks:

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.

**Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.**