Dimensional Fund Advisors reports 5.0% stake in MDU Resources (NYSE: MDU)

Rhea-AI Filing Summary

Dimensional Fund Advisors LP, an institutional investment adviser, reports deemed beneficial ownership of 10,435,060 shares of MDU Resources Group Inc common stock, representing 5.0% of the outstanding class. It has sole power to vote 10,287,408 shares and sole power to dispose of all 10,435,060 shares, with no shared voting or dispositive authority.

The shares are owned by various investment companies, commingled funds, group trusts and separate accounts for which Dimensional or its subsidiaries provide advisory or management services. Dimensional states that all securities are owned by these funds and expressly disclaims beneficial ownership of the shares beyond what is required for Section 13(d) reporting. To Dimensional’s knowledge, no individual fund holds more than 5% of the class.

Key Figures

Beneficial ownership: 10,435,060 shares Ownership percentage: 5.0 % Sole voting power: 10,287,408 shares +3 more

6 metrics

Beneficial ownership 10,435,060 shares Shares of MDU Resources Group Inc common stock deemed beneficially owned by Dimensional Fund Advisors LP

Ownership percentage 5.0 % Percentage of MDU Resources Group Inc common stock class beneficially owned

Sole voting power 10,287,408 shares Shares over which Dimensional Fund Advisors LP has sole power to vote or direct the vote

Shared voting power 0 shares Shares over which Dimensional Fund Advisors LP has shared power to vote

Sole dispositive power 10,435,060 shares Shares over which Dimensional Fund Advisors LP has sole power to dispose or direct the disposition

Shared dispositive power 0 shares Shares over which Dimensional Fund Advisors LP has shared power to dispose

Key Terms

beneficial owner, sole voting power, disclaims beneficial ownership, Investment Company Act of 1940, +1 more

5 terms

beneficial owner financial

"may be deemed to be the beneficial owner of the shares of the Issuer"

A beneficial owner is the person who ultimately owns or controls a financial asset or property, even if their name isn't directly on official documents. Think of it like someone who secretly holds the keys to a safe deposit box—others may appear to have access, but the true owner is the one who benefits from what's inside. Identifying beneficial owners helps ensure transparency and prevent illegal activities like money laundering or fraud.

sole voting power financial

"Sole power to vote or to direct the vote: 10,287,408"

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.

disclaims beneficial ownership financial

"Dimensional disclaims beneficial ownership of such securities"

Investment Company Act of 1940 regulatory

"four investment companies registered under the Investment Company Act of 1940"

A U.S. federal law that sets the rulebook for pooled investment vehicles such as mutual funds, exchange-traded funds and similar money managers, requiring them to register with regulators, disclose holdings and fees, limit conflicts of interest, and follow governance standards. It matters to investors because these protections and transparency rules act like a referee and scoreboard, helping people compare funds, trust that managers follow fair practices, and spot hidden costs or risks.

Section 13(d) of the Securities Exchange Act of 1934 regulatory

"for any other purposes than Section 13(d) of the Securities Exchange Act of 1934"

Section 13(d) of the Securities Exchange Act of 1934 is a U.S. rule that requires anyone who buys more than 5% of a public company’s shares to publicly disclose who they are, how many shares they own, and their intentions toward the company. For investors, this is like a neighborhood alert when someone acquires a large stake in a building: it reveals potential changes in control or strategy that could affect the stock’s price, governance, or future direction.

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

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Available on EDGAR 07/14/2026 - 01:29 PM Accepted by SEC EDGAR 07/14/2026 - 01:27 PM Learn about SEC filing dates

FAQ

What percentage of MDU (MDU) is held by Dimensional Fund Advisors?

Dimensional Fund Advisors reports deemed beneficial ownership of 5.0% of MDU Resources Group Inc’s common stock, corresponding to 10,435,060 shares held across client funds it advises or manages.

How many MDU (MDU) shares does Dimensional have sole voting power over?

Dimensional Fund Advisors has sole power to vote or direct the vote of 10,287,408 MDU Resources common shares, with no shared voting power reported in the ownership disclosure.

Does Dimensional share dispositive power over MDU (MDU) shares with others?

No. Dimensional Fund Advisors reports sole dispositive power over 10,435,060 MDU Resources shares and 0 shares with shared dispositive power, indicating exclusive authority to direct their disposition.

Who is the actual owner of the MDU (MDU) shares reported by Dimensional?

All MDU Resources shares are owned by the funds and accounts advised or managed by Dimensional or its subsidiaries. Dimensional may be deemed a beneficial owner for Section 13(d) purposes but disclaims beneficial ownership of the securities.

Does any single Dimensional-advised fund own more than 5% of MDU (MDU)?

According to Dimensional, the interest of any one fund in MDU Resources does not exceed 5% of the common stock class, with the reported 5.0% stake spread across multiple client funds.

What is Dimensional Fund Advisors’ legal status in relation to its MDU (MDU) holdings?

Dimensional Fund Advisors LP is described as an investment adviser registered under Section 203 of the Investment Advisers Act of 1940 and may be deemed a beneficial owner for Section 13(d) reporting, while disclaiming ownership of client securities.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 1)

MDU Resources Group Inc

(Name of Issuer)

Common Stock

(Title of Class of Securities)

552690109

(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): 552690109

1

Names of Reporting Persons

Dimensional Fund Advisors LP

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 10,287,408.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 10,435,060.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

10,435,060.00

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)

5.0 %

12

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13G

Item 1.
(a)	Name of issuer: MDU Resources Group Inc
(b)	Address of issuer's principal executive offices: 1200 West Century Avenue, Bismarck, ND 58503
Item 2.
(a)	Name of person filing: Dimensional Fund Advisors LP
(b)	Address or principal business office or, if none, residence: 6300 Bee Cave Road, Building One, Austin, TX 78746
(c)	Citizenship: Delaware Limited Partnership
(d)	Title of class of securities: Common Stock
(e)	CUSIP No.: 552690109
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: 10,435,060 ** see Note 1 ** ** Note 1 ** Dimensional Fund Advisors LP, an investment adviser registered under Section 203 of the Investment Advisors Act of 1940, furnishes investment advice to four investment companies registered under the Investment Company Act of 1940, and serves as investment manager or sub-adviser to certain other commingled funds, group trusts and separate accounts (such investment companies, trusts and accounts, collectively referred to as the "Funds"). In certain cases, subsidiaries of Dimensional Fund Advisors LP may act as an adviser or sub-adviser to certain Funds. In its role as investment advisor, sub-adviser and/or manager, Dimensional Fund Advisors LP or its subsidiaries (collectively, "Dimensional") may possess voting and/or investment power over the securities of the Issuer that are owned by the Funds, and may be deemed to be the beneficial owner of the shares of the Issuer held by the Funds. However, all securities reported in this schedule are owned by the Funds. Dimensional disclaims beneficial ownership of such securities. In addition, the filing of this Schedule 13G shall not be construed as an admission that the reporting person or any of its affiliates is the beneficial owner of any securities covered by this Schedule 13G for any other purposes than Section 13(d) of the Securities Exchange Act of 1934.
(b)	Percent of class: 5.0 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 10,287,408** see Note 1 **
	(ii) Shared power to vote or to direct the vote: 0
	(iii) Sole power to dispose or to direct the disposition of: 10,435,060** see Note 1 **
	(iv) Shared power to dispose or to direct the disposition of: 0
Item 5.	Ownership of 5 Percent or Less of a Class.
	Ownership of 5 percent or less of a class
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required. The Funds described in Note 1 above have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of the securities held in their respective accounts. To the knowledge of Dimensional, the interest of any one such Fund does not exceed 5% of the class of securities. Dimensional Fund Advisors LP disclaims beneficial ownership of all such securities.
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.

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.

Dimensional Fund Advisors LP

Signature:	Selwyn Notelovitz
Name/Title:	Global Chief Compliance Officer
Date:	07/14/2026