Mill Road Capital boosts Mistras Group (MG) stake to 1.87M shares with puts

Rhea-AI Filing Summary

Mill Road Capital III, L.P. has amended its Schedule 13D on Mistras Group, Inc., reporting beneficial ownership of 1,870,580 shares of common stock. This represents 5.9% of Mistras’s outstanding shares, based on 31,816,681 shares outstanding as of March 31, 2026.

The fund acquired these shares for an aggregate $12,723,026, using working capital and margin loan facilities. Recent activity includes multiple open‑market purchases between February 24 and March 20, 2026, some resulting from assignments of exchange‑traded put options previously sold by the fund.

Mill Road Capital III, L.P. holds sole voting and dispositive power over the 1,870,580 shares, with Mill Road Capital III GP LLC exercising authority as general partner and Thomas E. Lynch sharing voting and dispositive authority through his role at the GP. The fund also has outstanding standard American‑style, exchange‑traded put options on Mistras stock with strike prices of $12.50, $15.00, $17.50, and $20.00, expiring on May 15, 2026 and November 20, 2026.

Key Figures

Beneficial ownership: 1,870,580 shares Ownership percentage: 5.9% Shares outstanding: 31,816,681 shares +4 more

7 metrics

Beneficial ownership 1,870,580 shares Common stock held by each reporting person as of April 23, 2026

Ownership percentage 5.9% Portion of Mistras Group common stock outstanding as of March 31, 2026

Shares outstanding 31,816,681 shares Mistras Group common stock issued and outstanding as of March 31, 2026

Aggregate purchase cost $12,723,026 Total consideration paid to acquire 1,870,580 Mistras shares

Open-market purchase 83,800 shares at $15.00 Bought on March 20, 2026, some via put option assignments

Put options strike $12.50–$20.00 per share Strike prices of standard American‑style, exchange‑traded puts sold

Put options expirations May 15, 2026 and Nov 20, 2026 Expiration dates of outstanding Mistras Group put options

Key Terms

beneficial ownership, margin loan facilities, standard American-style, exchange-traded put options, sole voting and dispositive power, +1 more

5 terms

beneficial ownership financial

"The percentages of beneficial ownership reported in this Item 5..."

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

margin loan facilities financial

"using working capital from the Fund and the proceeds of margin loans under margin loan facilities maintained..."

standard American-style, exchange-traded put options financial

"The table below lists the standard American-style, exchange-traded put options ("Put Options") sold by the Fund..."

sole voting and dispositive power financial

"The Fund directly holds, and thus has sole voting and dispositive power over, 1,870,580 shares..."

Schedule 13D regulatory

"This Amendment No. 2 to the joint statement on with respect to the common stock..."

A Schedule 13D is a legal document that investors file with regulators when they buy a large enough stake in a company to potentially influence its management or decisions. It provides details about the investor’s intention, ownership stake, and plans, helping other investors understand who is gaining control and what their motives might be.

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)

60649T107

(CUSIP Number)

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

Peter M. Rosenblum, Esq.
Foley Hoag LLP, 155 Seaport Blvd.
Boston, MA, 02210
617-832-1000

(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)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

schemaVersion:

SCHEDULE 13D

CUSIP Number(s): 60649T107

1

Name of reporting person

Mill Road Capital III, L.P.

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

WC

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

CAYMAN ISLANDS

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 1,870,580.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 1,870,580.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

1,870,580.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

5.9 %

14

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13D

CUSIP Number(s): 60649T107

1

Name of reporting person

Mill Road Capital III GP LLC

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

CAYMAN ISLANDS

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 1,870,580.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 1,870,580.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

1,870,580.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

5.9 %

14

Type of Reporting Person (See Instructions)

HC, OO

SCHEDULE 13D

CUSIP Number(s): 60649T107

1

Name of reporting person

Thomas E. Lynch

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 1,870,580.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 1,870,580.00

11

Aggregate amount beneficially owned by each reporting person

1,870,580.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

5.9 %

14

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13D

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, NEW JERSEY , 08550.
Item 1 Comment: 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 3.	Source and Amount of Funds or Other Consideration
	Item 3 of the Schedule 13D shall hereby be amended and restated in its entirety as follows: The Reporting Persons have acquired beneficial ownership of an aggregate of 1,870,580 shares of Common Stock for $12,723,026 using working capital from the Fund and the proceeds of margin loans under margin loan facilities maintained in the ordinary course of business by the Fund with a broker on customary terms and conditions. The purchase price of shares acquired pursuant to the assignment of Put Options (as defined in Item 6) is not reduced by the premium received by the Reporting Persons upon sale of the Put Options.
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.

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

Mill Road Capital III GP LLC

Signature:	/s/ Deven Petito
Name/Title:	Deven Petito, Management Committee Director
Date:	04/23/2026

Thomas E. Lynch

Signature:	/s/ Deven Petito
Name/Title:	Deven Petito, attorney-in-fact
Date:	04/23/2026

FAQ

How many Mistras Group (MG) shares does Mill Road Capital currently own?

Mill Road Capital III, L.P. beneficially owns 1,870,580 shares of Mistras Group common stock. This stake equals 5.9% of the company’s outstanding shares, based on 31,816,681 shares reported as outstanding as of March 31, 2026.

What percentage of Mistras Group (MG) does Mill Road Capital’s stake represent?

Mill Road Capital’s reported holdings represent 5.9% of Mistras Group’s common stock. This percentage is calculated using 31,816,681 shares issued and outstanding as of March 31, 2026, as disclosed in Mistras’s definitive proxy statement on Schedule 14A.

How much has Mill Road Capital paid in total for its Mistras Group (MG) position?

Mill Road Capital reports paying an aggregate of $12,723,026 to acquire its 1,870,580 Mistras shares. The firm used working capital from its fund and proceeds of margin loans under margin loan facilities maintained with a broker on customary terms.

How did Mill Road Capital finance its purchase of Mistras Group (MG) shares?

Mill Road Capital financed its Mistras stake using working capital from its fund and margin loan facilities with a broker. These margin loans were maintained in the ordinary course of business and used together with fund capital to reach $12,723,026 of total share purchases.

What recent Mistras Group (MG) share purchases did Mill Road Capital make?

During the reporting period ending April 23, 2026, Mill Road Capital’s fund bought Mistras shares in several open‑market trades, including 83,800 shares at $15.00 on March 20, 2026 and 67,900 shares at $15.00 on March 19, 2026, among other transactions.

What put option positions on Mistras Group (MG) has Mill Road Capital sold?

Mill Road Capital’s fund sold standard American‑style, exchange‑traded put options on Mistras stock. Outstanding positions include puts with $15.00, $17.50, and $20.00 strike prices, expiring on May 15, 2026 and November 20, 2026, covering multiple hundreds of underlying shares.