T. Rowe Price Investment Management (MIAX) discloses 5.3% holding in Miami International

Rhea-AI Filing Summary

T. Rowe Price Investment Management, Inc., a Maryland corporation, filed a Schedule 13G reporting a significant position in Miami International Holdings common stock. The firm reports beneficial ownership of 5,032,970 shares, representing 5.3% of the class.

T. Rowe Price Investment Management reports sole voting power5,019,927 shares and sole dispositive power5,032,970 shares, with no shared voting or dispositive power. The firm expressly states that this filing should not be construed as an admission that it is the beneficial owner of these securities and that such beneficial ownership is denied.

Key Figures

Shares beneficially owned: 5,032,970 shares Percent of class owned: 5.3% Sole voting power: 5,019,927 shares +1 more

4 metrics

Shares beneficially owned 5,032,970 shares Common stock of Miami International Holdings reported on Schedule 13G

Percent of class owned 5.3% Percentage of Miami International Holdings common stock class

Sole voting power 5,019,927 shares Shares over which T. Rowe Price Investment Management has sole voting power

Sole dispositive power 5,032,970 shares Shares over which T. Rowe Price Investment Management has sole dispositive power

Key Terms

beneficially owned, Sole voting power, Sole dispositive power, Percent of class

4 terms

beneficially owned financial

"Ownership (a) | Amount beneficially owned: 5032970"

Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.

Sole voting power financial

"5 | Sole Voting Power 5,019,927.00"

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.

Sole dispositive power financial

"7 | Sole Dispositive Power 5,032,970.00"

Sole dispositive power is the exclusive legal authority to decide what happens to a security — for example, whether to sell, transfer, or retain shares — without needing anyone else’s permission. Investors care because it signals who truly controls the economic outcome of an investment: like holding the only key to a safe, the holder can realize gains or losses and may trigger regulatory reporting, insider rules, or influence over corporate ownership.

Percent of class financial

"Ownership (b) | Percent of class: 5.3 %"

Percent of class is the portion of a specific category of securities—such as a company’s common shares, preferred shares, or a bond series—that takes part in or approves a corporate action (vote, consent, tender, etc.). Investors watch this number because it reveals how much support or opposition exists within that particular shareholder group; like counting how many members of a club back a proposal, it can determine whether a plan passes or how influence is distributed.

FAQ

What stake in MIAX does T. Rowe Price Investment Management report?

T. Rowe Price Investment Management reports beneficial ownership of 5,032,970 shares of Miami International Holdings (MIAX) common stock, representing 5.3% of the outstanding class according to its Schedule 13G filing.

How much voting power does T. Rowe Price Investment Management have in MIAX?

The firm reports sole voting power over 5,019,927 shares of MIAX common stock and no shared voting power. This indicates it can vote those shares independently, subject to its internal and client arrangements.

What is the difference between voting and dispositive power in the MIAX 13G filing?

T. Rowe Price Investment Management reports sole voting power over 5,019,927 shares but sole dispositive power over 5,032,970 shares, meaning it can decide how slightly more shares are held or sold than it directly votes.

Does T. Rowe Price Investment Management admit being the beneficial owner of MIAX shares?

No. The firm explicitly states that the filing shall not be construed as an admission that it is the beneficial owner of the MIAX securities referenced and that such beneficial ownership is expressly denied.

What class of MIAX securities is covered by this Schedule 13G?

The Schedule 13G relates to Miami International Holdings common stock, identified in the filing as the title of class of securities: COMMON STOCK, with CUSIP number 59356Q108.

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Available on EDGAR 08/14/2026 - 10:41 AM Accepted by SEC EDGAR 08/14/2026 - 10:39 AM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

MIAMI INTERNATIONAL HOLDINGS

(Name of Issuer)

COMMON STOCK

(Title of Class of Securities)

59356Q108

(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 Number(s): 59356Q108

1

Names of Reporting Persons

T. Rowe Price Investment Management, Inc.

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

MARYLAND

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 5,019,927.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 5,032,970.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

5,032,970.00

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)

5.3 %

12

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13G

Item 1.
(a)	Name of issuer: MIAMI INTERNATIONAL HOLDINGS
(b)	Address of issuer's principal executive offices: 7 ROSZEL ROAD, FIFTH FLOOR, SUITE 1-A, PRINCETON, NJ, 08540
Item 2.
(a)	Name of person filing: T. Rowe Price Investment Management, Inc.
(b)	Address or principal business office or, if none, residence: 1307 Point Street, Baltimore, MD 21231
(c)	Citizenship: Maryland
(d)	Title of class of securities: COMMON STOCK
(e)	CUSIP Number(s): 59356Q108
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: 5032970
(b)	Percent of class: 5.3 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 5019927
	(ii) Shared power to vote or to direct the vote: 0
	(iii) Sole power to dispose or to direct the disposition of: 5032970
	(iv) Shared power to dispose or to direct the disposition of: 0
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 acquired and are held in the ordinary course of business and 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. T. Rowe Price Investment Management, Inc. hereby declares and affirms that the filing of Schedule 13G shall not be construed as an admission that Price Investment Management is the beneficial owner of the securities referred to, which beneficial ownership is expressly denied.

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.

T. Rowe Price Investment Management, Inc.

Signature:	Ellen York
Name/Title:	Vice President
Date:	08/14/2026