# EDGAR Filing Document

**Accession Number:** 0001436126
**File Stem:** 0001193125-26-174325
**Filing Date:** 2026-4
**Character Count:** 18457
**Document Hash:** caa13cf2f433ae862ef0de7dd79a9186
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-26-174325.hdr.sgml**: 20260423

**ACCESSION NUMBER**: 0001193125-26-174325

**CONFORMED SUBMISSION TYPE**: SCHEDULE 13D/A

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20260423

**DATE AS OF CHANGE**: 20260423

**SUBJECT COMPANY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Mistras Group, Inc.
- **CENTRAL INDEX KEY:** 0001436126
- **STANDARD INDUSTRIAL CLASSIFICATION:** SERVICES-ENGINEERING SERVICES [8711]
- **ORGANIZATION NAME:** 07 Trade & Services
- **EIN:** 223341267
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 005-85079
- **FILM NUMBER:** 26890120

**BUSINESS ADDRESS:**
- **STREET 1:** 195 CLARKSVILLE ROAD
- **CITY:** PRINCETON JUNCTION
- **STATE:** NJ
- **ZIP:** 08550
- **BUSINESS PHONE:** 609-716-4000

**MAIL ADDRESS:**
- **STREET 1:** 195 CLARKSVILLE ROAD
- **CITY:** PRINCETON JUNCTION
- **STATE:** NJ
- **ZIP:** 08550
**FILED BY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Mill Road Capital III, L.P.
- **CENTRAL INDEX KEY:** 0001767199

**ORGANIZATION NAME:**
- **EIN:** 981461868
- **STATE OF INCORPORATION:** E9
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A

**BUSINESS ADDRESS:**
- **STREET 1:** 334 PEMBERWICK ROAD
- **STREET 2:** SECOND FLOOR
- **CITY:** GREENWICH
- **STATE:** CT
- **ZIP:** 06831
- **BUSINESS PHONE:** 203-987-3500

**MAIL ADDRESS:**
- **STREET 1:** C/O MILL ROAD CAPITAL MANAGEMENT LLC
- **STREET 2:** 328 PEMBERWICK ROAD
- **CITY:** GREENWICH
- **STATE:** CT
- **ZIP:** 06831

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

## SCHEDULE 13D

### Under the Securities Exchange Act of 1934

**(Amendment No. 2)**

**Mistras Group, Inc.**

*(Name of Issuer)*

**Common stock, $0.01 par value**

*(Title of Class of Securities)*

**—**

*(CUSIP Number)*

**Mill Road Capital III, L.P.**<br>Attn: Thomas E. Lynch<br>328 Pemberwick Road<br>Greenwich CT 06831<br>203-987-3500

*(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)*

**04/21/2026**

*(Date of Event Which Requires Filing of this Statement)*

| **CUSIP No.** | **—** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Mill Road Capital III, L.P.** | Name of reporting person<br>**Mill Road Capital III, L.P.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**WC** | Source of funds (See Instructions)<br>**WC** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**CAYMAN ISLANDS** | Citizenship or place of organization<br>**CAYMAN ISLANDS** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**1870580.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**1870580.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**0.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**1870580.00** | Aggregate amount beneficially owned by each reporting person<br>**1870580.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**5.9%** | Percent of class represented by amount in Row (11)<br>**5.9%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**PN** | Type of Reporting Person (See Instructions)<br>**PN** | |

---

| **CUSIP No.** | **—** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Mill Road Capital III GP LLC** | Name of reporting person<br>**Mill Road Capital III GP LLC** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**AF** | Source of funds (See Instructions)<br>**AF** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**CAYMAN ISLANDS** | Citizenship or place of organization<br>**CAYMAN ISLANDS** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**1870580.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**1870580.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**0.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**1870580.00** | Aggregate amount beneficially owned by each reporting person<br>**1870580.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**5.9%** | Percent of class represented by amount in Row (11)<br>**5.9%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**HC** | Type of Reporting Person (See Instructions)<br>**HC** | |

---

| **CUSIP No.** | **—** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Thomas E. Lynch** | Name of reporting person<br>**Thomas E. Lynch** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**AF** | Source of funds (See Instructions)<br>**AF** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**X1** | Citizenship or place of organization<br>**X1** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**1870580.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**1870580.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**1870580.00** | Aggregate amount beneficially owned by each reporting person<br>**1870580.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**5.9%** | Percent of class represented by amount in Row (11)<br>**5.9%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**HC** | Type of Reporting Person (See Instructions)<br>**HC** | |

---

**Item 1. Security and Issuer**

**(a) Title of Class of Securities:**
Common stock, $0.01 par value

**(b) Name of Issuer:**
Mistras Group, Inc.

**(c) Address of Issuer's Principal Executive Offices:**
195 Clarksville Road, Princeton Junction, NJ, 08550

This Amendment No. 2 to the joint statement on Schedule 13D with respect to the common stock, par value $0.01 (the "Common Stock"), of Mistras Group, Inc., a Delaware corporation (the "Issuer"), filed by Thomas E. Lynch, Mill Road Capital III GP LLC, a Cayman Islands limited liability company, and Mill Road Capital III, L.P., a Cayman Islands exempted limited partnership (collectively, the "Reporting Persons") on July 9, 2024, as amended by Amendment No. 1 on Schedule 13D with respect to the Common Stock filed by the Reporting Persons on March 10, 2025 (such joint statement, as so amended and as amended herein, the "Schedule 13D"), amends the Schedule 13D as follows:

**Item 5. Interest in Securities of the Issuer**

**(a)**
Paragraph (a) of Item 5 of the Schedule 13D shall hereby be amended and restated in full as follows:

The percentages of beneficial ownership reported in this Item 5, and on each Reporting Person's cover page to this Schedule 13D, are based on a total of 31,816,681 shares of Common Stock issued and outstanding as of March 31, 2026, as reported in the definitive proxy statement on Schedule 14A filed by the Issuer on April 7, 2026. All of the share numbers reported herein are as of April 23, 2026, unless otherwise indicated. Each Reporting Person's cover page to this Schedule 13D is incorporated by reference into this Item 5(a, b).

Each of the Reporting Persons beneficially owns 1,870,580 shares of Common Stock, or approximately 5.9% of the outstanding shares of Common Stock, and the Reporting Persons beneficially own, in the aggregate, 1,870,580 shares of Common Stock, or approximately 5.9% of the outstanding shares of Common Stock.

**(b)**
Paragraph (b) of Item 5 of the Schedule 13D shall hereby be amended and restated in full as follows:

The Fund directly holds, and thus has sole voting and dispositive power over, 1,870,580 shares of Common Stock. The GP, as sole general partner of the Fund, also has sole authority to vote (or direct the vote of), and to dispose (or direct the disposal) of, these shares on behalf of the Fund, and Mr. Lynch has shared authority to vote (or direct the vote of), and to dispose (or direct the disposal) of, these shares in his capacity as Chairman and Management Committee Director of the GP.

**(c)**
Paragraph (c) of Item 5 of the Schedule 13D shall hereby be amended and restated in full as follows:

Except as otherwise described in this Schedule 13D, no Reporting Person, other than the Fund as set forth in the table below, effected any transaction in the Common Stock from February 22, 2026 (the date 60 days prior to the filing of this Schedule 13D) to April 23, 2026 (the "Reporting Period"):

Date of Purchase                              Shares Purchased (#)                                   Purchase Price per Share ($)

2/24/2026                                           160                                                                      $14.6400
3/9/2026*                                            2,700                                                                   $17.5000
3/9/2026                                             15,085                                                                 $13.9062
3/10/2026*                                          500                                                                      $17.5000
3/12/2026*                                          700                                                                      $17.5000
3/19/2026*                                          67,900                                                                 $15.0000
3/19/2026                                           10,654                                                                 $13.9583
3/20/2026*                                          83,800                                                                 $15.0000
3/20/2026*                                         16,400                                                                  $17.5000

*Effected pursuant to the assignment of Put Options

Except as otherwise described in this Schedule 13D, the above-listed transactions were conducted in the ordinary course of business on the open market for cash, and the purchase prices do not reflect brokerage commissions paid.

In addition, during the Reporting Period, the Fund sold the Put Options described in Item 6, which is incorporated by reference into this Item 5(c).

**Item 6. Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer.**

Item 6 of the Schedule 13D shall hereby be amended and restated in full as follows:

The table below lists the standard American-style, exchange-traded put options ("Put Options") sold by the Fund during the Reporting Period that are outstanding as of April 23, 2026.  Each of the below listed transactions was conducted in the ordinary course of business on the open market for cash, and the sale prices do not reflect brokerage commissions paid.

Date of Sale                            Value per Underlying                  Shares Underlying                Put Options' Strike               Put Options'
                                                 Share at which Put                      Put Options (100s)               Price per Share ($)               Expiration Date
                                                 Options were Sold ($)

3/5/2026                                  $0.5000                                          2                                            $12.50                                     5/15/2026
3/5/2026                                  $1.5000                                          6                                            $15.00                                     5/15/2026
3/6/2026                                  $1.6465                                          75                                          $15.00                                     5/15/2026
3/9/2026                                  $0.5702                                          85                                          $12.50                                     5/15/2026
3/9/2026                                  $1.7028                                          355                                        $15.00                                     5/15/2026
3/11/2026                                $1.5825                                          186                                        $15.00                                     5/15/2026
3/12/2026                                $1.6167                                          45                                          $15.00                                     5/15/2026
3/13/2026                                $1.6378                                          41                                          $15.00                                     5/15/2026
3/18/2026                                $1.5500                                          58                                          $15.00                                     5/15/2026
3/19/2026                                $1.6209                                          86                                          $15.00                                     5/15/2026
4/16/2026                                $1.1806                                          575                                        $17.50                                     5/15/2026
4/20/2026                                $3.5060                                          915                                        $20.00                                     11/20/2026
4/21/2026                                $3.4559                                          1,136                                     $20.00                                     11/20/2026
4/22/2026                                $3.4000                                           3                                           $20.00                                     11/20/2026

Each Put Option gives the holder the right (but not the obligation) to sell to the Fund and require the Fund to purchase, on or before the expiration date, the number of underlying shares of Common Stock, at a purchase price per share equal to the strike price. If a Put Option is assigned (exercised) on or before its expiration date, the Fund must purchase the shares of Common Stock underlying such Put Option in exchange for the aggregate exercise price.

Except as otherwise described in this Schedule 13D, including the Exhibits attached hereto, there are no contracts, arrangements, understandings or relationships (legal or otherwise) among the Reporting Persons, or between the Reporting Persons and any third party, with respect to any securities of the Issuer, including, but not limited to, those involving the transfer or voting of securities, finder's fees, joint ventures, loan or option arrangements, puts or calls, guarantees of profits, division of profits or losses, or the giving or withholding of proxies.

### SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** Mill Road Capital III, L.P.

**Signature:** /s/ Deven Petito

**Name/Title:** Deven Petito, Management Committee Director of Mill Road Capital III GP LLC, its General Partner

**Date:** 04/23/2026

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** Mill Road Capital III GP LLC

**Signature:** /s/ Deven Petito

**Name/Title:** Deven Petito, Management Committee Director

**Date:** 04/23/2026

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** Thomas E. Lynch

**Signature:** /s/ Deven Petito

**Name/Title:** Deven Petito, attorney-in-fact

**Date:** 04/23/2026