MDU RESOURCES GROUP INC

Note 1 -Basis of presentation

The accompanying consolidated interim financial statements were prepared in accordance with GAAP for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Interim financial statements do not include all disclosures provided in annual financial statements and, accordingly, these financial statements should be read in conjunction with those appearing in the 2025 Annual Report. The information is unaudited but includes all adjustments that are, in the opinion of management, necessary for a fair presentation of the accompanying consolidated interim financial statements and are of a normal recurring nature. Depreciation and amortization expense is reported separately on the Consolidated Statements of Income and therefore is excluded from the other line items within operating expenses.

On September 30, 2026, the Company reached a positive final investment decision to proceed with Bakken East. As a result, preliminary investigation costs incurred in 2026 prior to the final investment decision were reclassified from Other noncurrent assets to CWIP within Property, plant and equipment on the Consolidated Balance Sheets as of September 30, 2026, and are reflected as investing activities in the Consolidated Statement of Cash Flows. Additionally, $11.0 million of costs incurred in prior fiscal years were also reclassified from Other noncurrent assets to CWIP within Property, plant, and equipment on the Consolidated Balance Sheets as of September 30, 2026. The prior year reclassification represents a non-cash investing activity and is excluded from the main body of the Consolidated Statement of Cash Flows.

Management has evaluated the impact of events occurring after September 30, 2026, up to the date of issuance of these consolidated interim financial statements on November 5, 2026, that would require recognition or disclosure in the Consolidated Financial Statements.