MDU RESOURCES GROUP INC

Note 9 -Debt

Due to the Knife River separation, Centennial repaid all of its outstanding debt in the second quarter of 2023, which was funded by the Knife River repayment and the Company entering into various new debt instruments. Refer to Note 3 for additional information related to the repayment of debt associated with the Knife River separation.

Certain debt instruments of the Company and its subsidiaries contain restrictive and financial covenants and cross-default provisions. In order to borrow under the respective debt agreements, the Company and its subsidiaries must be in compliance with the applicable covenants and certain other conditions. Intermountain was not in compliance with its minimum interest coverage ratio for the period ended September 30, 2025, which constituted an event of default under the terms of the Intermountain NPAs. In addition, the event of default under the terms of the Intermountain NPAs constituted a cross-default under the terms of certain NPAs of MDU Energy Capital and revolving credit agreements held by the Company and Intermountain. Subsequent to September 30, 2025, Intermountain and MDU Energy Capital obtained waivers for this non-compliance from the holders of a majority of their respective outstanding notes, and Intermountain and the Company obtained waivers from the lenders of the revolving credit agreements, which collectively cured the impact of any events of default. The Company and its subsidiaries were in compliance with applicable covenants at December 31, 2025. In the event the Company or its subsidiaries do not comply with the applicable covenants and other conditions, alternative sources of funding may need to be pursued.

Credit facilities

Montana-Dakota's commercial paper program is supported by a revolving credit agreement. While the amount of commercial paper outstanding does not reduce available capacity under the revolving credit agreement, Montana-Dakota does not issue commercial paper in an aggregate amount exceeding the available capacity under the credit agreement. Commercial paper borrowings under this agreement are classified as long-term debt as they are intended to be refinanced on a long-term basis through continued commercial paper borrowings. The commercial paper and revolving credit agreement borrowings may vary during the period, largely the result of fluctuations in working capital requirements due to the seasonality of certain operations of Montana-Dakota.

The Company's borrowings under revolving credit agreements are classified as long-term debt as they are intended to be refinanced on a long-term basis through continued borrowings. All of the credit agreements contain customary covenants and provisions, including covenants not to permit, as of the end of any fiscal quarter, the ratio of funded debt to total capitalization (determined on a consolidated basis) to be greater than 65 percent. Other covenants include restrictions on the sale of certain assets, limitations on indebtedness and the making of certain investments.

Montana-Dakota On December 11, 2025, Montana-Dakota amended and restated its revolving credit agreement to extend the maturity date from October 18, 2028 to December 11, 2030. This amendment sets forth the terms and conditions under which the syndicate of lenders would make loans to or for the benefit of Montana-Dakota. These terms and conditions outline the pricing level and applicable facility fee for borrowings or letters of credit under the agreement. Montana-Dakota's revolving credit agreement supports its commercial paper program.

Cascade On December 11, 2025, Cascade amended and restated its revolving credit agreement to extend the maturity date from June 20, 2029 to December 11, 2030. This amendment sets forth the terms and conditions under which the syndicate of lenders would make loans to or for the benefit of Cascade. These terms and conditions outline the pricing level and applicable facility fee for borrowings or letters of credit under the agreement. Any borrowings under the revolving credit agreement are classified as long-term debt as they are intended to be refinanced on a long-term basis through continued borrowings.

MDU Resources Group, Inc. Form 10-K 89

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Intermountain On December 11, 2025, Intermountain amended and restated its revolving credit agreement to extend the maturity date from June 20, 2029 to December 11, 2030. This amendment sets forth the terms and conditions under which the syndicate of lenders would make loans to or for the benefit of Intermountain. These terms and conditions outline the pricing level, pricing level change date and applicable facility fee for borrowings or letters of credit under the agreement. Upon the pricing level change date, Intermountain is required under the agreement to deliver financial statements and officers compliance certificate to the assigned administrative agent. Any borrowings under the revolving credit agreement are classified as long-term debt as they are intended to be refinanced on a long-term basis through continued borrowings.

MDU Resources Group, Inc. On December 11, 2025, the Company amended and restated its revolving credit agreement to extend the maturity date from May 31, 2028 to December 11, 2030. This amendment sets forth the terms and conditions under which the syndicate of lenders would make loans to or for the benefit of MDU Resources Group, Inc. These terms and conditions outline the pricing level and applicable facility fee for borrowings or letters of credit under the agreement. Any borrowings under the revolving credit agreement are classified as long-term debt as they are intended to be refinanced on a long-term basis through continued borrowings.

The following table summarizes the outstanding revolving credit facilities of the Company and its subsidiaries:

Long-term debt

Long-term Debt Outstanding Long-term debt outstanding was as follows:

Montana-Dakota On July 11, 2024, Montana-Dakota issued $125.0 million of senior notes under a NPA with maturity dates of July 11, 2039 and July 11, 2054, at a weighted average interest rate of 5.96 percent. The agreement contains customary covenants and provisions, including a covenant of Montana-Dakota not to permit, at any time, the ratio of total debt to capitalization to be greater than 65 percent. The covenants also include certain restrictions on the sale of certain assets, loans and investments.

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On October 28, 2025, Montana-Dakota entered into a NPA to issue $250.0 million of senior notes, with maturity dates of October 28, 2035, October 28, 2040, and February 2, 2056, at a weighted average interest rate of 5.96 percent. On October 28, 2025, Montana-Dakota issued $150.0 million in senior notes under the NPA with the remaining $100.0 million issued on February 2, 2026. The agreement contains customary covenants and provisions, including a covenant of Montana-Dakota not to permit, at any time, the ratio of total debt to capitalization to be greater than 65 percent. Other covenants include a minimum interest coverage ratio and restrictions on the sale of certain assets.

On December 30, 2025, Montana-Dakota entered into a $250.0 million term loan agreement with a SOFR-based variable interest rate and a maturity date of January 29, 2027. On February 3, 2026, Montana-Dakota paid down $100.0 million of the outstanding balance under the term loan agreement. The agreement contains customary covenants and provisions, including a covenant of Montana-Dakota not to permit, at any time, the ratio of total debt to capitalization to be greater than 65 percent. The covenants also include certain restrictions on the sale of certain assets, loans, and investments.

Intermountain On July 15, 2025, Intermountain entered into a NPA to issue a total of $50.0 million of senior notes, with a maturity date of July 15, 2055, at an interest rate of 6.39 percent. On July 15, 2025, Intermountain issued $25.0 million in senior notes under the NPA with the remaining $25.0 million issued on November 14, 2025. This NPA is one of three distinct Intermountain NPAs that contain certain customary covenants, including a minimum interest coverage ratio.

WBI Energy Transmission On January 15, 2026, WBI Energy Transmission extended its $350.0 million uncommitted note purchase and private shelf agreement from December 22, 2025 to December 22, 2028, unless either party terminates such issuance right. WBI Energy Transmission had $235.0 million of notes outstanding at December 31, 2025, which reduced the remaining capacity under this uncommitted private shelf agreement to $115.0 million. The principal amount and interest rate of any series of shelf notes will be determined at the applicable time of issuance and purchase. On December 22, 2025, WBI Energy Transmission entered into a NPA to issue a total of $20.0 million of senior notes, with a maturity date of December 22, 2045, at an interest rate of 6.29 percent. This agreement contains customary covenants and provisions, including a covenant of WBI Energy Transmission not to permit, as of the end of any fiscal quarter, the ratio of total debt to total capitalization to be greater than 55 percent. Other covenants include a limitation on priority debt, restrictions on the sale of certain assets and the making of certain investments.

On April 1, 2024, WBI Energy Transmission entered into a $60.0 million term loan agreement with an interest rate of 4.52 percent and a maturity date of April 1, 2039, with the principal to be repaid in equal annual installments of $4.0 million each, beginning March 2025 and continuing through the maturity date. The agreement contains customary covenants and provisions, including a covenant of WBI Energy Transmission not to permit, at any time, the ratio of total debt to total capitalization to be greater than 65 percent. The covenants also include certain restrictions on the sale of certain assets, loans and investments.

WBI Energy Transmission's ratio of total debt to total capitalization at December 31, 2025 was 39 percent.

Schedule of Debt Maturities Long-term debt maturities, which excludes unamortized debt issuance costs and discount, for the five years and thereafter following December 31, 2025, were as follows: