Mistras Group major holder reports 19.2% stake

Rhea-AI Filing Summary

Mistras Group, Inc. has a significant shareholder, Aspasia Vahaviolos, who reports beneficial ownership of 6,105,650 shares of common stock on a Schedule 13G/A. This consists of 1,794,839 shares held directly and 4,310,811 shares held in a grantor retained annuity trust. The trust is overseen by her daughter as trustee, who currently holds the power to vote and dispose of the trust shares. Based on 31,849,893 shares outstanding as of August 5, 2026, Vahaviolos’ holdings represent 19.2% of Mistras Group’s common stock, giving her a sizable position with both sole and shared voting and dispositive powers.

Key Figures

Beneficially owned shares: 6,105,650 shares Directly held shares: 1,794,839 shares Trust-held shares: 4,310,811 shares +4 more

7 metrics

Beneficially owned shares 6,105,650 shares Total beneficial ownership reported by Aspasia Vahaviolos

Directly held shares 1,794,839 shares Shares of Mistras Group common stock held directly

Trust-held shares 4,310,811 shares Shares held in a grantor retained annuity trust

Ownership percentage 19.2% Portion of Mistras Group common stock beneficially owned

Shares outstanding 31,849,893 shares Outstanding shares of Mistras Group as of August 5, 2026

Sole voting power 1,794,839 shares Shares over which Vahaviolos has sole power to vote

Shared voting power 4,310,811 shares Shares over which voting power is shared via the trust

Key Terms

grantor retained annuity trust, beneficial ownership, sole voting power, shared dispositive power

4 terms

grantor retained annuity trust financial

"4,310,811 shares held in a grantor retained annuity trust (the "Trust")."

A grantor retained annuity trust (GRAT) is an estate-planning tool where the person who creates the trust transfers assets into it but receives fixed cash payments (an annuity) from the trust for a set number of years; whatever remains after that term passes to designated beneficiaries. It matters to investors because it can shift future appreciation of assets out of the creator’s taxable estate—like putting an asset into a timed vending machine that pays you fixed amounts while any extra value that grows inside the machine goes to heirs with reduced gift or estate tax consequences.

beneficial ownership financial

"The Reporting Person may be deemed to have beneficial ownership of the shares"

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.

sole voting power financial

"Sole Voting Power 1,794,839.00"

Sole voting power is the exclusive right to cast votes attached to a shareholder’s stock without needing approval from anyone else. Like holding the only remote control for a TV, it lets that holder decide corporate matters such as board members, mergers, and policy changes, making it important to investors because it concentrates control and can strongly influence a company’s strategy and the value of its shares.

shared dispositive power financial

"Shared Dispositive Power 4,310,811.00"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

How many Mistras Group (MG) shares does Aspasia Vahaviolos beneficially own?

Aspasia Vahaviolos beneficially owns 6,105,650 Mistras Group shares. This includes 1,794,839 shares held directly and 4,310,811 shares held through a grantor retained annuity trust associated with her.

What percentage of Mistras Group (MG) does Aspasia Vahaviolos own?

Aspasia Vahaviolos reports beneficial ownership of 19.2% of Mistras Group’s common stock. This percentage is calculated using 31,849,893 outstanding shares as of August 5, 2026, as reported by the company.

How are Aspasia Vahaviolos’ Mistras Group (MG) shares held?

Her 6,105,650 shares are split between 1,794,839 shares held directly and 4,310,811 shares held in a grantor retained annuity trust. Her daughter is trustee and has current voting and disposition power over the trust shares.

What voting powers does Aspasia Vahaviolos report for Mistras Group (MG)?

She reports 1,794,839 shares with sole voting power and 4,310,811 shares with shared voting power. The shared voting power relates to shares held in a grantor retained annuity trust managed by her daughter as trustee.

Why is Aspasia Vahaviolos deemed to have beneficial ownership of MG shares held in the trust?

She may be deemed to have beneficial ownership of the trust’s 4,310,811 shares because she has a potential right to re-acquire those shares within sixty days, even though her daughter currently controls voting and disposition as trustee.

What outstanding share count did Mistras Group (MG) use to calculate the 19.2% ownership?

The 19.2% ownership figure is based on 31,849,893 Mistras Group shares outstanding as of August 5, 2026. This outstanding share count was reported by the company and used to calculate the reported ownership percentage.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 08/13/2026 - 04:22 PM Accepted by SEC EDGAR 08/13/2026 - 04:21 PM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 1)

Mistras Group, Inc.

(Name of Issuer)

Common Stock, $0.01 par value

(Title of Class of Securities)

(CUSIP Number)

06/30/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP No.

1

Names of Reporting Persons

Aspasia Felice Vahaviolos

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 1,794,839.00
6	Shared Voting Power 4,310,811.00
7	Sole Dispositive Power 1,794,839.00
8	Shared Dispositive Power 4,310,811.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

6,105,650.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

19.2 %

12

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Mistras Group, Inc.
(b)	Address of issuer's principal executive offices: 195 Clarksville Road, Princeton Junction, NJ, 08550.
Item 2.
(a)	Name of person filing: Aspasia Vahaviolos
(b)	Address or principal business office or, if none, residence: 7 Ridgeview Road Princeton, NJ 08540
(c)	Citizenship: United States of America
(d)	Title of class of securities: Common Stock, $0.01 par value
(e)	CUSIP No.:
Item 4.	Ownership
(a)	Amount beneficially owned: 6,105,650* * The 6,105,650 shares reported as beneficially owned by the Reporting Person consists of (i) 1,794,839 shares held directly by the Reporting Person and (ii) 4,310,811 shares held in a grantor retained annuity trust (the "Trust"). The Reporting Person's daughter, who does not reside with her, is the trustee for the Trust and currently holds power over the voting and disposition of the shares of common stock held by the Trust. The Reporting Person may be deemed to have beneficial ownership of the shares held by the Trust because of a potential right to re-acquire the shares within sixty days.
(b)	Percent of class: 19.2* * This percentage calculation is based on 31,849,893 outstanding shares as of August 5, 2026 as reported by the issuer.
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 1,794,839
	(ii) Shared power to vote or to direct the vote: 4,310,811
	(iii) Sole power to dispose or to direct the disposition of: 1,794,839
	(iv) Shared power to dispose or to direct the disposition of: 4,310,811
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	Not Applicable
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

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.

Aspasia Felice Vahaviolos

Signature:	/s/ Aspasia Vahaviolos
Name/Title:	Aspasia Vahaviolos
Date:	08/13/2026