What changed in this filing

/stocks — the workspaceLOADING

Item 8. Financial Statements and Supplementary Data

2026-02-20 compared with 2025-02-20 · 413 added, 481 removed, 1470 unchanged (38% of the section changed)

19 unchanged sentences

We have audited the accompanying consolidated balance sheets of MDU Resources Group, Inc.

and subsidiaries (the "Company") as of December 31, 2024 and 2023, the related consolidated statements of income, comprehensive income, equity, and cash flows for each of the three years in the period ended December 31, 2024, and the related notes and the schedule listed in the Index at Item 15 (collectively referred to as the "financial statements").

In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2024 and 2023, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2024, in conformity with accounting principles generally accepted in the United States of America.

and subsidiaries (the “Company”) as of December 31, 2025 and December 31, 2024, the related consolidated statements of income, comprehensive income, equity, and cash flows for each of the three years in the period ended December 31, 2025, and the related notes and the schedules listed in the Index at Item 15 (collectively referred to as the “financial statements”).

In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2025 and December 31, 2024, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2025, in conformity with accounting principles generally accepted in the United States of America.

We have also audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the Company’s internal control over financial reporting as of December 31, 2025, based on criteria established in Internal Control—Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission and our report dated February 20, 2026, expressed an unqualified opinion on the Company’s internal control over financial reporting.

10 unchanged sentences

We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matters

The critical audit matters communicated below are matters arising from the current-period audit of the financial statements that were communicated or required to be communicated to the audit committee and that (1) relate to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective, or complex judgments.

The communication of critical audit matters does not alter in any way our opinion on the financial statements, taken as a whole, and we are not, by communicating the critical audit matters below, providing separate opinions on the critical audit matters or on the accounts or disclosures to which they relate.

Critical Audit Matter

The critical audit matter communicated below is a matter arising from the current-period audit of the financial statements that was communicated or required to be communicated to the audit committee and that (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective, or complex judgments.

The communication of critical audit matters does not alter in any way our opinion on the financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.

Regulatory Matters—Impact of Rate Regulation on the Financial Statements—Refer to Notes 2 and 6 to the financial statements

9 unchanged sentences

and income taxes.

64 MDU Resources Group, Inc.

Rates are determined and approved in regulatory proceedings based on an analysis of the Company’s costs to provide utility service and a return on the Company’s investment in the regulated businesses.

2 unchanged sentences

Decisions to be made by the Commissions in the future will impact the accounting for regulated operations.

We identified the impact of rate regulation as a critical audit matter due to the significant judgments made by management to support its assertions about impacted account balances and disclosures and the degree of subjectivity involved in assessing the impact of future regulatory orders on the

58 MDU Resources Group, Inc.

financial statements.

Management judgments include assessing the likelihood of (1) recovery in future rates of incurred costs and (2) refunds or future rate reduction to customers.

12 unchanged sentences

We also inquired of management regarding current year rate filings and new regulatory assets or liabilities.

Operating Revenues of Discontinued Operations - Construction Contracts with Customers—Refer to Note 3 to the financial statements

Critical Audit Matter Description

The Company recognized certain construction contract revenue over time using an input method based on the ratio of incurred costs to total estimated costs of the performance obligation (the cost-to-cost method) when this method was determined to best depict the transfer of the related performance obligation to the customer.

This method depends largely on the ability of management to make reasonably dependable estimates related to the extent of progress toward completion of the contract and the contract’s transaction price, which estimates involve management’s judgment.

Assumptions as to the occurrence of future events and the likelihood and amount of variable consideration, including liquidated damages, performance bonuses or incentives, claims, unpriced change orders and penalties or index pricing are made during the contract performance period.

The Company estimated variable consideration at the most likely amount it expects to be entitled and included those estimated amounts in the transaction price to the extent it was probable that a significant reversal of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration was resolved.

Given the judgments necessary to account for the Company’s construction contracts including the use of estimates to determine the transaction price and total costs for the performance obligations which are used to recognize revenue for construction contracts, auditing such estimates required extensive audit effort due to the volume and complexity of construction contracts and a high degree of auditor judgment when performing audit procedures and evaluating the results of those procedures.

How the Critical Audit Matter Was Addressed in the Audit

Our audit procedures related to management’s estimates of the transaction price and total costs for the performance obligations used to recognize revenue for construction contracts included the following, among others:

• We developed an expectation of the amount of construction contract revenues for certain performance obligations based on prior year markups, and taking into account current year events, applied to the construction contract costs in the current year and compared our expectation to the amount of construction contract revenues recorded by management.

MDU Resources Group, Inc.

• We selected a sample of construction contracts and performed the following:

– Evaluated whether the contracts were properly included in management’s calculation of construction contract revenue based on the terms and conditions of each contract, including whether continuous transfer of control to the customer occurred as progress was made toward fulfilling the performance obligation.

– Observed the work sites and inspected the progress toward completion for certain construction contracts.

– Compared the transaction prices, including estimated variable consideration, to the consideration expected to be received based on current rights and obligations under the contracts and any modifications that were agreed upon with the customers.

– Confirmed the transaction prices with the customer.

– Evaluated management’s identification of distinct performance obligations by evaluating whether the underlying goods and services were highly interdependent and interrelated.

– Tested the accuracy and occurrence of the costs incurred to date for the performance obligation.

– We evaluated the reasonableness of the estimated variable consideration in the contract revenue by evaluating the information supporting management’s judgement as to their estimate of the most likely amount it expects to receive without a significant reversal of cumulative revenue occurring when the uncertainty associated with the variable consideration is resolved.

– Evaluated the estimates of total cost for the performance obligation by:

– Evaluating management’s ability to achieve the estimates of total cost and profit by performing corroborating inquiries with the Company’s project managers and engineers, and comparing the estimates to management’s work plans, engineering specifications, and/or supplier contracts for certain selected contracts.

– Comparing management’s estimates for the selected contracts to costs and profits of similar performance obligations, when applicable.

– Tested the mathematical accuracy of management’s calculation of construction contract revenue for the performance obligation for certain selected contracts.

• We evaluated management’s ability to estimate total costs and profits accurately by comparing actual costs and profits to management’s historical estimates for performance obligations that have been fulfilled.

/s/ DELOITTE & TOUCHE LLP

9 unchanged sentences

In our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, 2025, based on criteria established in Internal Control — Integrated Framework (2013) issued by COSO.

We have also audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the consolidated financial statements as of and for the year ended December 31, 2024, of the Company and our report dated February 20, 2025, expressed an unqualified opinion on those consolidated financial statements.

We have also audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the consolidated financial statements as of and for the year ended December 31, 2025, of the Company and our report dated February 20, 2026, expressed an unqualified opinion on those financial statements.

Basis for Opinion

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Operation and maintenance 433,023 414,491 407,081

414,491 407,081 379,951

Depreciation and amortization 206,708 200,078 190,450

200,078 190,450 188,560

Taxes, other than income 114,497 106,216 103,133

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Postretirement liability adjustment:

Postretirement liability gains (losses) arising during the period, net of tax of $ 360 , $( 201 ) and $ 3,965 in 2024, 2023 and 2022, respectively

Postretirement liability (losses) gains arising during the period, net of tax of $( 202 ), $ 360 and $( 201 ) in 2025, 2024 and 2023, respectively

( 397 ) 1,049 ( 646 )

Amortization of postretirement liability losses included in net periodic benefit credit, net of tax of $ 168 , $ 145 and $ 78 in 2025, 2024 and 2023, respectively

432 242 1,819

Reclassification of postretirement liability adjustment from regulatory asset, net of tax of $ 0 , $ 0 and $( 1,086 ) in 2024, 2023 and 2022, respectively

— — ( 3,265 )

Postretirement liability adjustment ( 42 ) 1,481 ( 404 )

Net unrealized gain (loss) on available-for-sale investments:

Net unrealized gain (loss) on available-for-sale investments arising during the period, net of tax of $ 23 , $ 46 and $( 177 ) in 2024, 2023 and 2022, respectively

85 173 ( 667 )

Net unrealized gain on available-for-sale investments:

Net unrealized gain on available-for-sale investments arising during the period, net of tax of $ 29 , $ 23 and $ 46 in 2025, 2024 and 2023, respectively

Reclassification adjustment for loss on available-for-sale investments included in net income, net of tax of $ 4 , $ 5 and $ 11 in 2025, 2024 and 2023, respectively

Net unrealized gain (loss) on available-for-sale investments

105 216 ( 553 )

Net unrealized gain on available-for-sale investments

Other comprehensive income (loss) 83 1,586 ( 107 )

7 unchanged sentences

Cash, cash equivalents and restricted cash $ 28,212 $ 66,904

$ 66,904 $ 60,473

Receivables, net 258,631 274,303

1 unchanged sentence

Inventories 39,052 44,940

Current environmental allowances

26,194 23,304

Prepayments and other current assets 40,768 41,372

Current assets of discontinued operations — 769,490

Total current assets 572,436 666,259

2 unchanged sentences

Less accumulated depreciation and amortization 2,304,787 2,209,771

2,209,771 2,076,375

Net property, plant and equipment 5,960,185 5,344,292

2 unchanged sentences

Investments 121,177 115,459

Environmental allowances

112,376 66,170

Other 213,078 178,552

Noncurrent assets of discontinued operations — 347,865

Total noncurrent assets 7,049,770 6,372,559

2 unchanged sentences

Current liabilities:

Short-term borrowings $ — $ 95,000

Long-term debt due within one year $ 144,700 $ 161,700

4 unchanged sentences

Accrued compensation 34,666 35,264

Current environmental obligations

24,086 19,561

Other accrued liabilities 110,917 104,953

Current liabilities of discontinued operations — 443,280

Total current liabilities 685,223 678,598

4 unchanged sentences

Asset retirement obligations 431,587 406,351

Environmental obligations

108,448 58,457

Other 182,261 173,438

Noncurrent liabilities of discontinued operations

Total noncurrent liabilities 4,164,066 3,669,646

Commitments and contingencies

Stockholders' equity:

19 unchanged sentences

Net income — — — 414,707 — — — 414,707

Other comprehensive income

Other comprehensive loss

— — — — ( 107 ) — — ( 107 )

2 unchanged sentences

Repurchase of common stock — — — — — ( 153,622 ) ( 4,811 ) ( 4,811 )

— — — — — ( 266,821 ) ( 7,399 ) ( 7,399 )

Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings — — ( 7,851 ) — — 153,622 4,811 ( 3,040 )

Separation of Knife River

( 538,921 ) ( 539 ) — ( 970,119 ) 12,306 538,921 3,626 ( 954,726 )

Issuance of common stock 65,197 65 1,268 — — — — 1,333

2 unchanged sentences

Net Income — — — 281,108 — — — 281,108

Other comprehensive loss

Other comprehensive income

— — — — 1,586 — — 1,586

1 unchanged sentence

Employee stock-based compensation — — 9,572 — — — — 9,572

Repurchase of common stock — — — — — ( 153,622 ) ( 4,811 ) ( 4,811 )

Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings 199,147 199 ( 2,822 ) — — — — ( 2,623 )

Separation of Knife River

Separation of Everus

— — — ( 400,316 ) — — — ( 400,316 )

4 unchanged sentences

Other comprehensive income — — — — 83 — — 83

— — — — 1,586 — — 1,586

Dividends declared on common stock — — — ( 111,200 ) — — — ( 111,200 )

1 unchanged sentence

Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings 396,592 396 ( 4,872 ) — — — — ( 4,476 )

Separation of Everus

— — — ( 400,316 ) — — — ( 400,316 )

Issuance of common stock 51,651 52 933 — — — — 985

8 unchanged sentences

Net income $ 190,395 $ 281,108 $ 414,707

Income from discontinued operations, net of tax 100,035 84,590 250,237

(loss) income from discontinued operations, net of tax ( 1,012 ) 100,035 84,590

Income from continuing operations 191,407 181,073 330,117

1 unchanged sentence

Depreciation and amortization 206,708 200,078 190,450

200,078 190,450 188,560

Deferred income taxes ( 8,923 ) ( 16,078 ) ( 1,309 )

3 unchanged sentences

Pension and postretirement benefit plan net periodic benefit credit ( 1,069 ) ( 3,837 ) ( 5,380 )

Unrealized (gains) losses on investments

Unrealized (gains) on investments

( 6,575 ) ( 5,942 ) ( 7,431 )

(Gains) losses on sales of assets ( 857 ) ( 347 ) 15

Losses (gains) on sales of assets 25 ( 857 ) ( 347 )

Gain on tax-free exchange of the retained shares in Knife River

9 unchanged sentences

Net cash provided by continuing operations 474,090 411,813 305,333

Net cash provided by discontinued operations 90,505 27,294 188,449

Net cash (used in) provided by discontinued operations ( 725 ) 90,505 27,294

Net cash provided by operating activities 473,365 502,318 332,627

3 unchanged sentences

Cost of removal, net of salvage value ( 11,283 ) ( 5,539 ) 1,170

( 5,539 ) 1,170 ( 11,779 )

Investments ( 4,182 ) ( 5,155 ) ( 2,423 )

Proceeds from investment cost basis withdrawal 9,000 20,000 —

Proceeds from investment excess cash and cost basis withdrawal

5,000 9,000 20,000

Net cash used in continuing operations ( 780,859 ) ( 523,827 ) ( 465,129 )

8 unchanged sentences

Costs of issuance of common stock ( 79 ) ( 50 ) —

( 50 ) — ( 150 )

Dividends paid ( 108,244 ) ( 102,939 ) ( 161,316 )

1 unchanged sentence

Tax withholding on stock-based compensation ( 4,476 ) ( 2,623 ) ( 3,040 )

Net cash (used in) provided by continuing operations ( 76,603 ) 230,228 ( 2,792 )

Net cash provided by (used in) continuing operations 268,802 ( 76,603 ) 230,228

Net cash provided by (used in) discontinued operations — 116,899 ( 25,606 )

Net cash provided by financing activities 268,802 40,296 204,622

(Decrease) increase in cash, cash equivalents and restricted cash ( 10,071 ) ( 3,542 ) 26,356

Decrease in cash, cash equivalents and restricted cash ( 38,692 ) ( 10,071 ) ( 3,542 )

Cash, cash equivalents and restricted cash - beginning of year 66,904 76,975 80,517

76,975 80,517 54,161

Cash, cash equivalents and restricted cash - end of year * $ 28,212 $ 66,904 $ 76,975

MDU Resources Group, Inc.

Supplemental cash flow information:

Cash expenditures during the year for:

Interest, net**

$ 99,210 $ 108,242 $ 112,839

*Includes cash of discontinued operations of $ 16.5 million and $ 9.7 million for the years ended December 31, 2023 and 2022, respectively.

Income taxes paid, net*** $ 30,838 $ 43,572 $ 12,162

Noncash investing and financing transactions:

Property, plant and equipment additions in accounts payable

$ 45,338 $ 36,820 $ 46,364

Right-of-use assets obtained in exchange for new operating lease liabilities

$ 14,905 $ 1,787 $ 2,265

Debt for equity exchange of retained shares in Knife River

$ — $ — $ 293,239

* Includes cash of discontinued operations of $ 16.5 million for the year ended December 31, 2023.

** AFUDC - borrowed was $ 7.4 million, $ 11.0 million and $ 10.0 million for the years ended December 31, 2025, 2024, and 2023, respectively.

*** Income taxes paid, including discontinued operations, were $ 30.8 million, $ 80.9 million and $ 62.5 million for the years ended December 31, 2025, 2024, and 2023, respectively.

The accompanying notes are an integral part of these consolidated financial statements.

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For more information on discontinued operations, see Note 3.

Additionally, certain amounts recorded in prior year financial statements have been reclassified to conform to the current year presentation.

The Company has reclassified $ 26.9 million and $ 27.4 million of transmission-related expenses from operation and maintenance to electric fuel and purchased power for the years ended December 31, 2023 and 2022, respectively, in the Consolidated Statements of Income.

These transmission-related expenses are an integral component of the cost of electricity sold to customers and therefore, more appropriately reflected in electric fuel and purchased power than operation and maintenance expense.

These reclassifications had no effect on previously reported results of operations or cash flows.

Management has also evaluated the impact of events occurring after December 31, 2025, up to the date of issuance of these consolidated financial statements on February 20, 2026, that would require recognition or disclosure in the financial statements.

5 unchanged sentences

See Note 16 for additional information.

MDU Resources Group, Inc.

Use of estimates

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Consequently, operating results can be affected by revisions to prior accounting estimates.

MDU Resources Group, Inc.

Note 2 - Significant Accounting Policies

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Recently adopted accounting standards

ASU 2022-06 - Reference Rate Reform:

Deferral of Sunset Date In December 2022, the FASB included a sunset provision within ASC 848 based on expectations of when LIBOR would cease being published.

At the time ASU 2020-04 was issued, the UK Financial Conduct Authority had established its intent to cease overnight tenors of LIBOR after December 31, 2021.

In March 2021, the UK Financial Conduct Authority announced that the intended cessation date of the overnight tenors of LIBOR would be June 30, 2023 which is beyond the current sunset date of ASC 848.

The amendments in this Update defer the sunset date of ASC 848 from December 31, 2022 to December 31, 2024, after which entities will no longer be permitted to apply the relief in ASC 848.

December 31, 2024 The Company has updated its credit agreements to include language regarding the successor or alternate rate to LIBOR.

The Company did not have a material impact on its results of operations, financial position, cash flows or disclosures.

ASU 2023-07 Segment Reporting - Improvements to Reportable Segment Disclosures

In November 2023, the FASB issued guidance on improving financial reporting by requiring disclosure of incremental segment information, primarily through enhanced disclosures about significant segment expenses, on an annual and interim basis for all public entities to enable investors to develop more decision-useful financial analyses.

December 31, 2024 The Company identified and updated disclosures to ensure compliance with the new guidance.

Recently issued accounting standards not yet adopted

ASU 2023-09 Income Taxes - Improvements to Income Tax Disclosures an Amendment, December 2023

In December 2023, the FASB issued guidance to address investors requests for more transparency about income tax information through improvements to income tax disclosures primarily related to the rate reconciliation and income taxes paid information and effectiveness of income tax disclosures.

Effective for annual reporting periods beginning after 2024 on a prospective basis.

The Company is currently evaluating the impact the guidance will have on its disclosures for the year ended December 31, 2025.

ASU 2023-09 Income Taxes - Improvements to Income Tax Disclosures an Amendment, December 2023 In December 2023, the FASB issued guidance to address investors requests for more transparency about income tax information through improvements to income tax disclosures primarily related to the rate reconciliation and income taxes paid information and effectiveness of income tax disclosures.

December 31, 2025 The Company has adopted the guidance prospectively and disclosures have been updated to ensure compliance with the new guidance.

ASU 2024-01 Compensation - Stock Compensation In March 2024, the FASB issued Improvements to GAAP through an example to demonstrate application of the scope of paragraph 718-10-15-3 to determine whether profits interest and similar awards should be accounted in Compensation - Stock Compensation.

Effective for fiscal year beginning after December 15, 2024.

The Company is currently evaluating the impact the guidance will have on its disclosures for the year ended December 31, 2025.

ASU 2024-03 Disaggregation of Income Statement Expenses

In November 2024, the FASB issued guidance to improve the disclosures about a public business entity's expenses and address requests from investors for more detailed information about the types of expenses (including purchases of inventory, employee compensation, depreciation, amortization, and depletion) in commonly presented expense captions (such as cost of sales, selling, general, and administrative;

December 31, 2025 The Company has evaluated and did not have a material impact from the scope clarification in the new guidance.

See Note 12 for additional information on Stock Compensation.

Recently issued accounting standards not yet adopted

ASU 2024-03 Disaggregation of Income Statement Expenses In November 2024, the FASB issued guidance to improve the disclosures about a public business entity's expenses and address requests from investors for more detailed information about the types of expenses (including purchases of inventory, employee compensation, depreciation, amortization, and depletion) in commonly presented expense captions (such as cost of sales, selling, general, and administrative;

and research and development).

1 unchanged sentence

The Company is currently evaluating the impact the guidance will have on its disclosures for the year ended December 31, 2027.

ASU 2025-05 Measurement of Credit Losses for Accounts Receivable and Contract Assets In July 2025, the FASB issued guidance on applying a practical expedient when estimating expected credit losses on current accounts receivable and/or current contract assets arising from transactions under ASC Topic 606 - Revenue from Contracts with Customers.

Effective for annual reporting periods beginning after December 15, 2025.

The Company is currently evaluating the impact the guidance will have on its results of operations, financial position, cash flows, and disclosures for the year ended December 31, 2026.

ASU 2025-06 Targeted Improvements to the Accounting of Internal-Use Software In September 2025, the FASB issued guidance on accounting for capitalization of development costs for internal-use software under ASC Subtopic 350-40 and the transition approaches to use.

Effective for annual reporting periods beginning after December 15, 2027.

The Company is currently evaluating the impact the guidance will have on its results of operations, financial position, cash flows, and disclosures for the year ended December 31, 2028.

ASU 2025-10 Accounting for Government Grants Received By Business Entities In December 2025, the FASB issued guidance on accounting for government grants received by business entities that are related to an asset (purchase, construction, or acquisition of a long-lived asset or inventory) or income (reimbursements to a business entity for operating expenses).

Effective for annual reporting periods beginning after December 15, 2028.

The Company is currently evaluating the impact the guidance will have on its results of operations, financial position, cash flows, and disclosures for the year ended December 31, 2029.

Cash, cash equivalents and restricted cash

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The Company's trade receivables are all due in 12 months or less.

The total balance of receivables past due 90 days or more was $ 3.6 million and $ 3.7 million at December 31, 2024 and 2023, respectively.

The total balance of receivables past due 90 days or more was $ 3.6 million at both December 31, 2025 and 2024.

MDU Resources Group, Inc.

The Company's expected credit losses are determined through a review using historical credit loss experience, changes in asset specific characteristics, current conditions and reasonable and supportable future forecasts, among other specific account data, and is performed at least quarterly.

3 unchanged sentences

Management has reviewed the balance reserved through the allowance for expected credit losses and believes it is reasonable.

MDU Resources Group, Inc.

Details of the Company's expected credit losses were as follows:

7 unchanged sentences

Less write-offs charged against the allowance

1,994 7,355 2 9,351

Credit loss recoveries collected

388 1,152 — 1,540

At December 31, 2023

414 1,189 — 1,603

Current expected credit loss provision 1,891 4,667 — 6,558

2 unchanged sentences

At December 31, 2024 473 1,366 — 1,839

Current expected credit loss provision 2,197 4,723 — 6,920

Less write-offs charged against the allowance 2,559 5,782 — 8,341

Credit loss recoveries collected 395 1,136 — 1,531

At December 31, 2025 $ 506 $ 1,443 $ — $ 1,949

Receivables also consist of accrued unbilled revenue representing revenues recognized in excess of amounts billed.

Accrued unbilled revenue at MDU Energy Capital was $ 143.2 million and $ 132.0 million at December 31, 2024 and 2023, respectively.

Accrued unbilled revenue within the electric and natural gas distribution segments was $ 128.1 million and $ 143.2 million at December 31, 2025 and 2024, respectively.

Inventories and natural gas in storage

7 unchanged sentences

Total $ 39,052 $ 44,940

The remainder of natural gas in storage, which largely represents the cost of gas required to maintain pressure levels for normal operating purposes, was included in noncurrent assets - other and was $ 48.5 million at both December 31, 2024 and 2023, respectively.

The remainder of natural gas in storage, which largely represents the cost of gas required to maintain pressure levels for normal operating purposes, was included in noncurrent assets - other and was $ 47.8 million and $ 48.5 million at December 31, 2025 and 2024, respectively.

76 MDU Resources Group, Inc.

Property, plant and equipment

12 unchanged sentences

These amounts are recorded as regulatory liabilities on the Consolidated Balance Sheets.

70 MDU Resources Group, Inc.

Impairment of long-lived assets, excluding goodwill

20 unchanged sentences

For more information on the Company's operating segments, see Note 14.

MDU Resources Group, Inc.

Goodwill impairment, if any, is measured by comparing the fair value of each reporting unit to its carrying value.

1 unchanged sentence

If the carrying value of a reporting unit exceeds its fair value, the Company must record an impairment loss for the amount that the carrying value of the reporting unit, including goodwill, exceeds the fair value of the reporting unit.

For the years ended December 31, 2024, 2023 and 2022, there were no impairment losses recorded.

For the years ended December 31, 2025, 2024 and 2023, the carrying amount of goodwill at the natural gas distribution segment, was $ 345.7 million.

There have been no impairment losses recorded.

The Company's investments include the cash surrender value of life insurance policies, insurance contracts, mortgage-backed securities and U.S.

11 unchanged sentences

The Company's evaluation of whether it qualifies as the primary beneficiary of a VIE involves significant judgments, estimates and assumptions and includes a qualitative analysis of the activities that most significantly impact the VIE's economic performance and whether the Company has the power to direct those activities, the design of the entity, the rights of the parties and the purpose of the arrangement.

MDU Resources Group, Inc.

Derivative instruments

14 unchanged sentences

If the rate is unknown or cannot be determined, the Company uses an incremental borrowing rate, which is determined by the length of the contract, asset class and the Company's borrowing rates, as of the commencement date of the contract.

78 MDU Resources Group, Inc.

Asset retirement obligations

2 unchanged sentences

Over time, the liability is accreted to its present value each period and the capitalized cost is depreciated over the useful life of the related asset.

Upon settlement of the liability, the Company either settles the obligation for the recorded amount or incurs a gain or loss at its non-regulated operations or incurs a regulatory asset or liability at its regulated operations.

Upon settlement of the liability, the Company either settles the obligation for the recorded amount or incurs a regulatory asset or liability.

Stock-based compensation

4 unchanged sentences

Inception-to-date expense was adjusted based upon the determination of the potential achievement of the performance target at each reporting date.

The Company recognized compensation expense related to PSAs with market-based performance metrics on a straight-line basis over the requisite service period.

The Company recognizes compensation expense related to PSAs with market-based performance metrics on a straight-line basis over the requisite service period.

Outstanding PSAs were converted to RSUs in connection with the completed separation of Knife River through the spinoff.

The Company records the compensation expense for PSAs using an estimated forfeiture rate.

The Company records the compensation expense for RSUs and PSAs using an estimated forfeiture rate.

The estimated forfeiture rate is calculated based on an average of actual historical forfeitures.

3 unchanged sentences

Basic earnings per share is computed by dividing net income by the weighted average number of shares of common stock outstanding during the year.

Diluted earnings per share is computed by dividing net income by the total of the weighted average number of shares of common stock outstanding during the year, plus the effect of nonvested performance share awards and restricted stock units.

Diluted earnings per share is computed by dividing net income by the total of the weighted average number of shares of common stock outstanding during the year, plus the effect of nonvested PSAs and RSUs, as well as potentially issuable shares pursuant to FSAs using the treasury stock method.

Common stock outstanding includes issued shares less shares held in treasury.

4 unchanged sentences

A reconciliation of the weighted average common shares outstanding used in the basic and diluted earnings per share calculations follows:

72 MDU Resources Group, Inc.

2025 2024 2023

1 unchanged sentence

Weighted average common shares outstanding - basic 204,291 203,867 203,640

Effect of dilutive performance share awards 786 298 104

Effect of dilutive PSAs, RSUs, and FSAs

1,009 786 298

Weighted average common shares outstanding - diluted 205,300 204,653 203,938

1 unchanged sentence

Income from continuing operations $ .94 $ .89 $ 1.62

$ .89 $ 1.62 $ .58

Discontinued operations, net of tax ( .01 ) .49 .42

3 unchanged sentences

Income from continuing operations $ .93 $ .88 $ 1.62

$ .88 $ 1.62 $ .58

Discontinued operations, net of tax — .49 .41

4 unchanged sentences

$ .5400 $ .5100 $ .6950

MDU Resources Group, Inc.

The Company provides deferred federal and state income taxes on all temporary differences between the book and tax basis of the Company's assets and liabilities by using enacted tax rates in effect for the year in which the differences are expected to reverse.

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The Company’s consolidated financial statements and accompanying notes for prior periods have been restated.

For the comparative periods, Everus' operations are only reflected through October 2024 compared to the full year in 2023 and 2022 and Knife River's operations are only reflected through May 2023 compared to the full year in 2022.

MDU Resources Group, Inc.

For the comparative periods, Everus' operations are only reflected through October 2024 compared to the full year in 2023 and Knife River's operations are only reflected through May 2023.

On April 25, 2023, Knife River issued $ 425.0 million of senior notes, pursuant to an indenture, due in 2031 to qualified institutional buyers.

4 unchanged sentences

Following the separation of Knife River, the 538,921 treasury shares were retired.

80 MDU Resources Group, Inc.

The Company provided to Knife River and Knife River provided to the Company transition services in accordance with the transition services agreement entered into on May 31, 2023.

3 unchanged sentences

The Company provided and will provide to Everus and Everus provided and will provide to the Company transition services in accordance with the transition services agreement entered into on October 31, 2024.

For the twelve months ended December 31, 2024, the Company received $ 727,000 ;

and paid $ 47,000 , for these related activities.

The majority of the transition services are expected to be provided for a period of approximately eighteen months , however, no longer than two years after the separation.

For the twelve months ended December 31, 2025 and 2024, the Company received $ 7.9 million, which include certain software costs and $ 727,000 , respectively;

and paid $ 49,000 and $ 47,000 , respectively, for these related activities.

The transition services are expected to be complete as of March 2026.

Separation related costs of $ 1.0 million, $ 41.7 million and $ 58.6 million net of tax, were incurred during the twelve months ended December 31, 2025, 2024 and 2023, respectively.

1 unchanged sentence

These charges primarily relate to transaction and third-party support costs, one-time business separation fees and related tax charges.

74 MDU Resources Group, Inc.

The Company had no assets or liabilities related to the discontinued operations of Knife River on its balance sheet as of December 31, 2024 and 2023.

The carrying amounts of the major classes of assets and liabilities related to the discontinued operations of Everus included in the Company’s Consolidated Balance Sheet at December 31, 2023 were as follows:

December 31, 2023

Assets (In Thousands)

Current assets:

Cash and cash equivalents $ 16,501

Receivables, net 692,629

Inventories 42,709

Prepayments and other current assets 17,651

Total current assets of discontinued operations 769,490

Noncurrent assets:

Net property, plant and equipment 116,018

Goodwill 143,224

Other intangible assets, net 2,004

Investments 11,760

Operating lease right-of-use assets 53,232

Total noncurrent assets of discontinued operations 347,865

Total assets of discontinued operations $ 1,117,355

Current liabilities:

Accounts payable $ 315,240

Taxes payable 8,557

Accrued compensation 44,721

Operating lease liabilities due within one year 21,143

Other accrued liabilities 53,619

Total current liabilities of discontinued operations 443,280

Noncurrent liabilities:

Long-term debt 132,000

Deferred income taxes 6,212

Operating lease liabilities 32,504

Total noncurrent liabilities of discontinued operations 179,650

Total liabilities of discontinued operations $ 622,930

The Company had no assets or liabilities related to the discontinued operations of Everus on its balance sheet as of December 31, 2025 or 2024.

The reconciliation of the major classes of income and expense constituting pretax income from discontinued operations to the after-tax income from discontinued operations on the Consolidated Statements of Income were as follows:

4 unchanged sentences

Operating (loss) income ( 1,158 ) 136,170 166,858

136,170 166,858 373,358

Other income (expense) 12,446 10,599 4,119

Other income — 12,446 10,599

Interest expense — 7,118 47,229

Income from discontinued operations before income taxes

141,498 130,228 338,887

Income taxes 41,463 45,638 88,650

(Loss) income from discontinued operations before income taxes ( 1,158 ) 141,498 130,228

Income tax (benefit) expense ( 146 ) 41,463 45,638

Discontinued operations, net of tax $ ( 1,012 ) $ 100,035 $ 84,590

MDU Resources Group, Inc.

Note 4 - Revenue from Contracts with Customers

4 unchanged sentences

As part of the adoption of ASC 606 - Revenue from Contracts with Customers , the Company elected the practical expedient to recognize the incremental costs of obtaining a contract as an expense when incurred if the amortization period of the asset that the Company otherwise would have recognized is 12 months or less.

MDU Resources Group, Inc.

Disaggregation

30 unchanged sentences

Total external operating revenues $ 414,406 $ 1,200,975 $ 142,597 $ — $ 1,757,978

76 MDU Resources Group, Inc.

Year ended December 31, 2023 Electric Natural gas distribution Pipeline Other Total

11 unchanged sentences

Total external operating revenues $ 401,037 $ 1,287,236 $ 115,079 $ — $ 1,803,352

82 MDU Resources Group, Inc.

Remaining performance obligations

1 unchanged sentence

The Company has applied the practical expedient that does not require additional disclosures for contracts with an original duration of less than 12 months to certain firm transportation and non-regulated contracts.

The Company's firm transportation and storage contracts included in the remaining performance obligations have weighted average remaining durations of less than five years and one year , respectively.

At December 31, 2024, the Company's remaining performance obligations were $ 606.5 million.

The Company expects to recognize the following revenue amounts in future periods related to these remaining performance obligations:

$ 82.1 million within the next 12 months or less;

$ 81.5 million within the next 13 to 24 months;

and $ 442.9 million in 25 months or more.

The Company's firm transportation and storage contracts included in the remaining performance obligations have weighted average remaining durations of less than four years and one year , respectively.

At December 31, 2025, the Company expects to recognize revenue in future periods from remaining performance obligations, as follows:

12 months or less Next 13-24 months

25 months or more Total

(In Millions)

$ 86.8 $ 79.1 $ 365.6 $ 531.5

Note 5 - Property, Plant and Equipment

20 unchanged sentences

Land and other

4,148 31,654 7

4,147 4,148 NM

Less accumulated depreciation and amortization

1 unchanged sentence

Net property, plant and equipment $ 5,960,185 $ 5,344,292

NM - not meaningful

MDU Resources Group, Inc.

Note 6 - Regulatory Assets and Liabilities

Note 6 - Regulatory Matters

Regulatory assets & liabilities

The following table summarizes the individual components of unamortized regulatory assets and liabilities as of December 31:

2 unchanged sentences

Regulatory assets:

Natural gas costs recoverable through rate adjustments Up to 1 year

$ 91,091 $ 98,844

Environmental compliance programs Up to 1 year

$ 78,784 $ 76,964

Conservation programs Up to 1 year

29,148 19,123

Electric fuel and purchased power deferral Up to 1 year

Natural gas costs recoverable through rate adjustments Up to 1 year

22,897 91,091

Decoupling mechanisms Up to 1 year

Cost recovery mechanisms Up to 1 year

Electric fuel and purchased power deferral Up to 1 year

Other Up to 1 year

6 unchanged sentences

Taxes recoverable from customers Over plant lives 12,250 12,221

Electric fuel and purchased power deferral Up to 2 years

Covid-19 deferred costs - 4,167 2,746

Covid-19 deferred costs Up to 3 years

Long-term debt refinancing costs Up to 37 years

Environmental compliance programs - — 66,806

Natural gas costs recoverable through rate adjustments Up to 2 years

Electric fuel and purchased power deferral - — 4,349

Other Up to 13 years

3 unchanged sentences

Environmental compliance Up to 1 year

$ 89,306 $ 72,387

Natural gas costs refundable through rate adjustments Up to 1 year

1 unchanged sentence

Margin sharing Up to 1 year

Provision for rate refund Up to 1 year

Taxes refundable to customers Up to 1 year

Provision for rate refund Up to 1 year

Conservation programs Up to 1 year

8 unchanged sentences

Pension and postretirement benefits ** 4,776 4,862

Environmental compliance programs - — 61,941

Other Up to 12 years

11 unchanged sentences

The compliance costs for these regulations and the revenues from the sale of the allocated emissions allowances are passed through to customers in rates and the Company has, accordingly, deferred the environmental compliance costs as a regulatory asset and proceeds from the sale of allowances as a regulatory liability.

For a discussion of the Company's most recent cases by jurisdiction, see Note 20.

If, for any reason, the Company's regulated businesses cease to meet the criteria for application of regulatory accounting for all or part of their operations, the regulatory assets and liabilities relating to those portions ceasing to meet such criteria would be written off and included in the statement of income or accumulated other comprehensive loss in the period in which the discontinuance of regulatory accounting occurs.

Regulatory proceedings

The Company regularly reviews the need for electric and natural gas rate changes in each of the jurisdictions in which service is provided.

The Company files for rate adjustments to seek recovery of operating costs and capital investments, as well as reasonable returns as allowed by regulators.

Certain regulatory proceedings and cases may also contain recurring mechanisms that can have an annual true-up.

Examples of these recurring mechanisms include:

infrastructure riders, transmission trackers, renewable resource cost adjustment riders, as well as weather normalization and decoupling mechanisms.

The Company is unable to predict the ultimate outcome of these matters, the timing of final decisions of the various regulators and courts, or the effect on the Company's results of operations, financial position or cash flows.

The following table summarizes the Company's significant regulatory proceedings and cases by jurisdiction:

State Filing Date Annual Revenue Increase (%) *

Annual Revenue Increase

(in millions) *

Status Key Drivers and Additional Information

General Rate Cases Pending

June 30, 2025 18.6 % $ 5.8 9.7 % Settlement agreement filed January 23, 2026

Final rates requested to be effective April 1, 2026

• Increases in operation and maintenance expense

• Investments made since the last rate case

• Corresponding depreciation on those infrastructure investments

• Settlement includes a stipulation to withdraw the requested Reliability and Safety Rider

September 30, 2025 20.2 % $ 14.1 10.8 % Pending

• Investments, including Badger Wind Farm

• Corresponding depreciation on those investments

• Increased operation and maintenance expense

Natural Gas Distribution

November 25, 2025 15.8 % $ 16.4 10.4 % Pending

• Rate base growth

• Growth in operations and maintenance expense

• Growth in depreciation expense associated with new investments in rate base

MDU Resources Group, Inc.

State Filing Date Annual Revenue Increase (%) *

Annual Revenue Increase

(in millions) *

Status Key Drivers and Additional Information

General Rate Cases Finalized

Natural Gas Distribution Washington

March 29, 2024 7.9 %

9.5 % Approved February 24, 2025

Final rates effective March 5, 2025

$ 3.7 M revenue reduction effective June 1, 2025

Final rates effective March 1, 2026, subject to provisional plant review

• Multi-year rate case

• Infrastructure investments necessary to provide safe and reliable service

• Higher operating costs due to inflation

• $ 3.7 M revenue reduction was driven by forecasted plant that was not placed in service by December 31, 2024

Natural Gas Distribution

May 30, 2025 4.2 % $ 13.0 9.5 % Approved

Final rates effective January 1, 2026

• Increased operating expenses

• Costs associated with plant additions

• Revenues necessary to produce a fair rate of return to enable continued safe and reliable service

Natural Gas Distribution

July 15, 2024 8.6 % $ 7.3 9.6 % Approved

Interim rates of $ 7.7 M effective February 1, 2025

Final rates effective November 1, 2025

• Investments in system upgrades pipeline replacement projects enhancing the reliability, safety and integrity of the natural gas system

• Increased costs to operate and maintain that system

Natural Gas Distribution

October 31, 2024 11.7 % $ 2.1 9.65 % Approved

Final rates effective August 1, 2025

• Investments in system upgrades and pipeline replacement projects enhancing the reliability, safety and integrity of the natural gas system

• Increased costs to operate and maintain that system

* Annual revenue increase and percent increase for general rate cases pending and general rate cases finalized, reflects the final approved amount or the amount reflected in the most recent settlement agreement, if applicable.

State Filing Date Annual Revenue Increase

(in millions)

Status Key Drivers and Additional Information

Other Filings

July 15, 2025 $ 7.2 Approved

Rates effective November 1, 2025 Transmission Cost Adjustment Rider

• Allows recovery of transmission costs, including capital investments, and associated revenue

Natural Gas Distribution Wyoming

August 15, 2025 N/A

System Safety and Integrity Rider

• Would allow Montana-Dakota to recover costs and expenses associated with a pipeline replacement program

September 30, 2025 N/A

Pending Systems Management Cost Adjustment Mechanism

• Recovery of transmission and wildfire related costs

Electric North Dakota

October 31, 2025 $ 25.3 Approved

Rates effective February 1, 2026

Renewable Resource Cost Adjustment

• Allows for annual adjustments for recent projected capital costs and related expenses for projects determined to be recoverable

• Update includes Badger Wind Farm

Electric South Dakota

October 31, 2025 $ 1.1 Pending Infrastructure Rider

• Allows annual adjustments for recent projected capital costs and related expenses for projects determined to be recoverable

• Update includes Badger Wind Farm

Note 7 - Environmental Allowances and Obligations

Beginning in 2023, the Company's natural gas distribution segment acquires environmental allowances as part of its requirement to comply with environmental regulations in certain states.

The Company's natural gas distribution segment acquires environmental allowances as part of its requirement to comply with environmental regulations in certain states.

Allowances are allocated by the respective states to the Company at no cost and additional allowances are required to be purchased as needed based on the requirements in the respective states.

The segment records purchased and allocated environmental allowances at weighted average cost under the inventory method of accounting.

Environmental allowances are included in Prepayments and other current assets and noncurrent assets - Other on the Consolidated Balance Sheets.

Environmental allowances are included as Current environmental allowances and Environmental allowances in current and noncurrent assets on the Consolidated Balance Sheets.

86 MDU Resources Group, Inc.

Environmental compliance obligations, which are based on GHG emissions, are measured at the carrying value of environmental allowances held plus the estimated value of additional allowances necessary to satisfy the compliance obligation.

Environmental compliance obligations are included in current liabilities - Other accrued liabilities and noncurrent liabilities - Other on the Consolidated Balance Sheets.

Environmental compliance obligations are included as Current environmental obligations and Environmental obligations in current and noncurrent liabilities on the Consolidated Balance Sheets.

The Company recognizes revenue from the sale of emissions allowances allocated under the environmental programs when the allowances are sold at auction.

3 unchanged sentences

For more information on the Company’s regulatory assets and liabilities, see Note 6.

Note 8 - Goodwill

The carrying amount of goodwill at the natural gas distribution segment, which remained unchanged, was $ 345.7 million, respectively, at both December 31, 2024 and 2023.

No impairments of goodwill have been recorded in these periods.

MDU Resources Group, Inc.

Note 8 - Fair Value Measurements

5 unchanged sentences

These investments, which totaled $ 67.4 million and $ 59.3 million at December 31, 2025 and 2024, respectively, are classified as Investments on the Consolidated Balance Sheets.

The net unrealized gain on these investments for the year ended December 31, 2024 and 2023, was $ 5.9 million and $ 7.4 million, respectively.

The net unrealized loss on these investments for the year ended December 31, 2022 was $ 11.2 million.

The net unrealized gain on these investments for the year ended December 31, 2025, 2024, and 2023 was $ 6.6 million, $ 5.9 million, and $ 7.4 million, respectively.

The change in fair value, which is considered part of the cost of the plan, is classified in Other income on the Consolidated Statements of Income.

In the first quarter of 2024 and the fourth quarter of 2023, the Company withdrew $ 9.0 million and $ 20.0 million, respectively, of its cost basis, which reduced Investments on the Consolidated Balance Sheets.

In the second quarter of 2025 the Company withdrew $ 5.0 million of cash in excess of 125 percent of the full funding amount, which had no effect on the cost basis of the investments held.

In the first quarter of 2024 the Company withdrew $ 9.0 million of its cost basis, which reduced Investments on the Consolidated Balance Sheets.

The Company did not elect the fair value option, which records gains and losses in income, for its available-for-sale securities, which include mortgage-backed securities and U.S.

42 unchanged sentences

Total assets measured at fair value $ — $ 83,739 $ — $ 83,739

* The insurance contracts invest approximately 60 percent in fixed-income investments, 15 percent in common stock of large-cap companies, 8 percent in target date investments, 7 percent in common stock of mid-cap companies, 5 percent in common stock of small-cap companies, 3 percent in cash equivalents, 1 percent in high yield investments, and 1 percent in international investments.

* The insurance contracts invest approximately 58 percent in fixed-income investments, 17 percent in common stock of large-cap companies, 8 percent in target date investments, 8 percent in common stock of mid-cap companies, 4 percent in common stock of small-cap companies, 4 percent in cash equivalents, and 1 percent in international investments.

The Company's money market funds are valued at the net asset value of shares held at the end of the period, based on published market quotations on active markets, or using other known sources including pricing from outside sources.

20 unchanged sentences

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, all of which the Company and its subsidiaries, as applicable, were in compliance with at December 31, 2024.

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.

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:

Company Facility Facility

Company Debt-to-Total Capitalization Ratio Provisions for Increased Borrowings, up to a maximum of:

Limit Amount Outstanding at December 31, 2025

3 unchanged sentences

Montana-Dakota Utilities Co.

Commercial paper/Revolving credit agreement (a) $ 200.0 $ 81.4 $ 144.2 $ — 10/18/28

55 % $ 250.0 $ 200.0 $ 132.0 $ 81.4 $ — 12/11/30

Cascade Natural Gas Corporation

Revolving credit agreement

$ 175.0 (b) $ 64.6 $ 15.4 $ 2.2 (c) 6/20/29

50 % $ 225.0 $ 175.0 $ 96.5 $ 64.6 $ 2.2 12/11/30

Intermountain Gas Company

Revolving credit agreement

52 % $ 225.0 $ 175.0 $ 67.3 $ 105.1 $ — 12/11/30

MDU Resources Group, Inc.

Revolving credit agreement

$ — $ — $ 12.1 (c) 5/31/28

(a) The commercial paper program is supported by a revolving credit agreement with various banks (provisions allow for increased borrowings, at the option of Montana-Dakota on stated conditions, up to a maximum of $ 250.0 million).

At December 31, 2024 and 2023, there were no amounts outstanding under the revolving credit agreement.

(b) Certain provisions allow for increased borrowings, up to a maximum of $ 225.0 million.

(d) Certain provisions allow for increased borrowings, up to a maximum of $ 250.0 million.

Montana-Dakota's commercial paper program is supported by a revolving credit agreement.

Short-term debt

Cascade On January 20, 2023, Cascade entered into a $ 150.0 million term loan agreement with a SOFR-based variable interest rate and a maturity date of January 19, 2024.

On December 5, 2023, Cascade paid down $ 100.0 million of the outstanding balance.

On January 19, 2024, Cascade made the final $ 50.0 million repayment on the term loan agreement.

Intermountain On January 20, 2023, Intermountain entered into a $ 125.0 million term loan agreement with a SOFR-based variable interest rate and a maturity date of January 19, 2024.

In March, April and May 2023, Intermountain paid down $ 20.0 million, $ 30.0 million, and $ 30.0 million, respectively, of the outstanding balance.

On January 19, 2024 Intermountain made the final $ 45.0 million repayment on the term loan agreement.

MDU Resources Group, Inc.

On May 31, 2023, the Company entered into a $ 150.0 million revolving credit agreement with a SOFR-based variable interest rate and a maturity date of May 29, 2024.

At December 31, 2023, the Company had no amount outstanding, which remained that way until this agreement matured and subsequently terminated in May 2024.

82 MDU Resources Group, Inc.

49 % $ 250.0 $ 200.0 $ 32.9 $ — $ 1.0 12/11/30

Long-term debt

2 unchanged sentences

(In thousands)

Senior notes due on dates ranging from August 23, 2025 to June 15, 2062

Senior notes due on dates ranging from July 15, 2026 to June 15, 2062

4.76 % $ 2,010,000 $ 1,947,000

Credit agreements due on June 20, 2029

Term loan agreements due on dates ranging from January 29, 2027 to April 1, 2039

4.68 % 310,900 65,600

Commercial paper supported by revolving credit agreement

Credit agreements due on December 11, 2030

5.17 % 196,700 169,700

Term loan agreements due on dates ranging from September 3, 2032 to April 1, 2039

Commercial paper supported by revolving credit agreement

4.00 % 132,000 81,400

1 unchanged sentence

7.32 % 35,000 35,000

Other notes due on dates ranging from May 31, 2028 to November 30, 2038

Other notes due on November 30, 2038

6.00 % 329 346

3 unchanged sentences

Net long-term debt $ 2,532,155 $ 2,130,910

Montana-Dakota On October 18, 2023, Montana-Dakota amended and restated its revolving credit agreement to increase the borrowing capacity to $ 200.0 million and extend the maturity date to October 18, 2028.

Montana-Dakota's revolving credit agreement supports its commercial paper program.

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 credit agreement contains customary covenants and provisions, including covenants of Montana-Dakota 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 limitations on the sale of certain assets and on the making of certain loans and investments.

On July 11, 2024, Montana-Dakota issued $ 125.0 million of senior notes under a note purchase agreement with maturity dates ranging from July 11, 2039 to July 11, 2054, at a weighted average interest rate of 5.96 percent.

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.

Montana-Dakota's ratio of total debt to total capitalization at December 31, 2024, was 48 percent.

Cascade On June 20, 2024, Cascade amended and restated its revolving credit agreement to increase the borrowing capacity from $ 100.0 million to $ 175.0 million and extend the maturity date to June 20, 2029.

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 credit agreement contains customary covenants and provisions, including a covenant of Cascade not to permit, at any time, the ratio of total debt to total capitalization 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.

Cascade's ratio of total debt to total capitalization at December 31, 2024, was 50 percent.

Intermountain On June 20, 2024, Intermountain amended and restated its revolving credit agreement to increase the borrowing capacity from $ 100.0 million to $ 175.0 million and extend the maturity date to June 20, 2029.

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 credit agreement contains customary covenants and provisions, including a covenant of Intermountain not to permit, at any time, the ratio of total debt to total capitalization 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.

Intermountain's ratio of total debt to total capitalization at December 31, 2024, was 60 percent.

90 MDU Resources Group, Inc.

On May 31, 2023, the Company entered into a $ 200.0 million revolving credit agreement with a SOFR-based variable interest rate and a maturity date of May 31, 2028.

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 credit agreement contains customary covenants and provisions, including a covenant of the Company not to permit, at any time, the ratio of total debt to total capitalization to be greater than 65 percent.

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.

On May 31, 2023, the Company entered into a $ 375.0 million term loan agreement with a SOFR-based variable interest rate and a maturity date of May 31, 2025.

On November 15, 2023, the Company paid down $ 185.0 million of the term loan agreement.

On November 1, 2024, the Company repaid its remaining outstanding balance of $ 190.0 million and the term loan agreement subsequently terminated.

The Company's repayment was

MDU Resources Group, Inc.

funded by the Everus repayment of debt in connection with the separation.

Refer to Note 3 for additional information related to the repayment of debt associated with the Everus separation.

The Company's ratio of total debt to total capitalization at December 31, 2024, was 46 percent.

WBI Energy Transmission WBI Energy Transmission has a $ 350.0 million uncommitted note purchase and private shelf agreement with an expiration date of December 22, 2025.

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.

10 unchanged sentences

The Company records obligations related to retirement costs of natural gas distribution lines, natural gas transmission lines, natural gas storage wells, decommissioning of certain electric generating facilities, special handling and disposal of hazardous materials at certain electric generating facilities, natural gas distribution facilities and buildings, and certain other obligations as asset retirement obligations.

MDU Resources Group, Inc.

A reconciliation of the Company's liability, which the current portion is included in other accrued liabilities on the Consolidated Balance Sheets, for the years ended December 31 was as follows:

4 unchanged sentences

Accretion expense**

20,883 19,655

Revisions in estimates ( 221 ) 4,388

Balance at end of year $ 431,916 $ 406,647

* 2025 includes $ 4.8 million for the future decommissioning of Badger Wind Farm.

** Includes $ 20.9 million and $ 19.6 million in 2025 and 2024, respectively, recorded to regulatory assets.

8 unchanged sentences

For the years ended December 31, 2025, 2024 and 2023, the dividends declared to common stockholders were $ 110.3 million, $ 103.9 million and $ 141.5 million, respectively.

84 MDU Resources Group, Inc.

The declaration and payment of dividends of the Company is at the sole discretion of the board of directors.

6 unchanged sentences

Any public offer and sale of such securities will be made only by means of a prospectus meeting the requirements of the Securities Act and the rules and regulations thereunder.

At-the-Market Offering Program On August 7, 2025, the Company entered into an EDA pursuant to which it may issue, offer, and sell, from time to time, up to an aggregate gross sales price of $ 400.0 million of shares of its common stock through an ATM offering program, which includes the ability to enter into FSAs.

Since the establishment of the ATM offering program, the Company did not issue common stock pursuant to the EDA nor enter into any FSAs related to the EDA.

Equity Forward Sale Agreements On December 5, 2025, the Company completed a follow-on public offering of 10,152,284 shares of the Company's common stock at a public offering price of $ 19.70 per share.

In addition, on December 23, 2025, the underwriters exercised their option to purchase 1,522,842 additional shares of common stock.

Pursuant to the FSAs entered into in connection with the offering, the Company has discretion to settle the FSAs on one or more settlement dates prior to December 6, 2027, subject to certain price adjustments as set forth in the FSAs as well as adjustments for transaction and other associated fees.

The FSAs will be physically settled with shares of common stock issued by the Company, unless the Company elects to settle the FSAs in net cash or net shares, subject to certain conditions.

If the Company elects to physically settle the FSAs, the Company will physically issue shares of common stock to the banking counterparties at the then-applicable forward sale price and receive proceeds at that time.

92 MDU Resources Group, Inc.

At December 31, 2025, the Company could have settled all of its outstanding FSAs with physical delivery of 11,675,126 shares of common stock to the banking counterparties in exchange for cash of approximately $ 221.1 million.

If the FSAs had been net cash or net share settled at December 31, 2025, the Company estimates that the counterparties, in aggregate, would have been entitled to a net settlement of $ 6.8 million or 349,596 shares, respectively.

The forward price used to determine amounts due at settlement is calculated based on the public offering price, subject to transaction and other associated fees, adjusted by the overnight bank funding rate, less a spread, and less expected dividends on the Company's common stock during the period the FSAs are outstanding.

The FSAs are indexed to the Company's stock and meets the other requirements for equity classification.

As a result of the equity classification, no gain or loss is recognized in earnings associated with the subsequent changes in fair value of the FSAs.

Stockholders' equity equal to cash proceeds net of deferred issuance costs will be recorded upon settlement.

FSAs earnings per share dilution Prior to settlement, the potentially issuable shares pursuant to the FSAs will be reflected in the Company's diluted earnings per share calculation using the treasury stock method.

Share dilution occurs when the average market price of the Company's stock during the reporting period is higher than the then-applicable forward sale price at the end of the reporting period.

For more information on earnings per share, see Note 2.

The K-Plan provides participants the option to invest in the Company's common stock.

13 unchanged sentences

The combined performance factors were determined based on the performance of the Company as of December 31, 2022.

As a result, there were no outstanding PSAs at December 31, 2023.

Outstanding awards at the time of the spinoffs were converted into awards of the holder’s employer following each separation.

The Company incurred $ 1.7 million of incremental compensation expense related to the conversion of the RSUs associated with the Everus spinoff, of which $ 854,000 was recognized in 2024 and the remainder will be recognized in expense over the remaining service periods of the applicable awards.

The Company incurred $ 1.7 million of incremental compensation expense related to the conversion of the RSUs associated with the Everus spinoff, of which $ 536,000 and $ 854,000 were recognized in 2025 and 2024, respectively, and the remainder will be recognized in expense over the remaining service period of the applicable awards.

Total stock-based compensation expense (after tax) was $ 5.9 million, $ 7.1 million and $ 5.1 million in 2025, 2024 and 2023, respectively.

The Company uses the straight-line amortization method to recognize compensation expense related to RSUs, which only has a service condition.

The Company recognized compensation expense related to PSAs with market-based performance metrics on a straight-line basis over the requisite service period.

The Company recognizes compensation expense related to PSAs with market-based and performance metrics on a straight-line basis over the requisite service period.

As of December 31, 2025, total remaining unrecognized compensation expense related to stock-based compensation was approximately $ 8.7 million (before income taxes) which will be amortized over a weighted average period of 1.3 years.

Non-employee directors receive shares of common stock in addition to and in lieu of cash payment for directors' fees.

There were 46,341 shares with a fair value of $ 850,000 , 50,717 shares with a fair value of $ 950,000 and 40,800 shares with a fair value of $ 1.2 million issued to non-employee directors during the years ended December 31, 2024, 2023 and 2022, respectively.

There were 51,651 shares with a fair value of $ 1.1 million, 46,341 shares with a fair value of $ 850,000 and 50,717 shares with a fair value of $ 950,000 issued to non-employee directors during the years ended December 31, 2025, 2024 and 2023, respectively.

MDU Resources Group, Inc.

Restricted stock units

In February 2025, 2024 and 2023, key employees were granted RSUs under the long-term performance-based incentive plan authorized by the Company's compensation committee.

4 unchanged sentences

As previously discussed, adjustments were made to the number of RSUs to preserve the intrinsic value of the awards in connection with the spinoffs of Knife River and Everus and outstanding PSAs in place at the time of the Knife River spinoff were converted to RSUs.

MDU Resources Group, Inc.

Target grants of RSUs outstanding at December 31, 2025, were as follows:

Grant Date Performance Period Target Grant of Shares

February 2023/ July 2023 2023-2025 542,233

February 2024/ June 2024 2024-2026 648,885

February 2025 2025-2027 126,910

A summary of the status of the RSUs for the year ended December 31, 2025, was as follows:

Number of Shares

Fair Value **

Nonvested at beginning of period 1,240,517 $ 12.56

Granted pre-separation of Everus

126,910 16.83

( 49,399 ) 12.12

Non-vested pre-separation of Everus

Adjustments related to the Everus separation*

Vested shares

1 unchanged sentence

Nonvested at end of period 775,795 $ 12.89

* Includes the conversion adjustments to preserve the intrinsic value of the awards and the cancellation of outstanding awards held by employees that transferred to Everus, which were replaced with awards issued by Everus as part of the separation.

* Weighted average grant-date fair values post-separation of Everus reflects incremental fair value related to modifying the awards and the Company's adjusted stock price due to the separation.

Historical PSAs

Performance share awards

In February 2025, key employees were granted PSAs under the long-term performance-based incentive plan authorized by the Company's compensation committee.

1 unchanged sentence

Upon vesting, participants receive dividends that accumulate during the vesting period.

Share awards were generally earned over a three-year vesting period and tied to financial metrics.

However, in connection with the spinoff of Knife River, the outstanding PSAs were converted to RSUs.

As a result, there were no outstanding PSAs at December 31, 2024.

Entitlement to performance shares is established by either the market condition or the performance metrics and service condition relative to the designated awards.

Target grants of PSAs outstanding at December 31, 2025, were as follows:

Grant Date Performance Period Target Grant of Shares

February 2025 2025-2027 296,128

94 MDU Resources Group, Inc.

Under the market condition for these PSAs, participants could earn from zero to 200 percent of the apportioned target grant of shares based on the Company's total stockholder return relative to that of the selected peer group.

Compensation expense was based on the grant-date fair value as determined by Monte Carlo simulation.

The blended volatility term structure ranges were comprised of 50 percent historical volatility and 50 percent implied volatility.

Compensation expense is based on the grant-date fair value as determined by Monte Carlo simulation.

The blended volatility term structure ranges are comprised of 50 percent historical volatility and 50 percent implied volatility.

Risk-free interest rates were based on U.S.

5 unchanged sentences

Weighted average discounted dividends per share $ 1.30

Under the performance conditions for these PSAs, participants could earn from zero to 200 percent of the apportioned target grant of shares.

The performance conditions were based on the Company's compound annual growth rate in earnings from continuing operations.

The weighted average grant-date fair value per share for the PSAs applicable to these performance conditions issued in 2022 was $ 27.73 .

The fair value of the PSAs that vested during the year ended December 31, 2022, was $ 7.6 million.

86 MDU Resources Group, Inc.

Note 14 - Accumulated Other Comprehensive Loss

The Company's accumulated other comprehensive loss is comprised of losses on derivative instruments qualifying as hedges, postretirement liability adjustments and gain (loss) on available-for-sale investments.

The after-tax changes in the components of accumulated other comprehensive loss were as follows:

as Hedges Post-

Adjustment Net

Gain (Loss) on

Investments Total

Comprehensive

(In thousands)

At December 31, 2022 $ ( 125 ) $ ( 29,900 ) $ ( 558 ) $ ( 30,583 )

Other comprehensive income (loss) before reclassifications — ( 646 ) 173 ( 473 )

Amounts reclassified from accumulated other comprehensive loss 81 242 43 366

Net current-period other comprehensive income (loss) 81 ( 404 ) 216 ( 107 )

Amounts reclassified related to the separation of Knife River 44 12,262 — 12,306

At December 31, 2023 — ( 18,042 ) ( 342 ) ( 18,384 )

Other comprehensive income before reclassifications

— 1,049 85 1,134

Amounts reclassified from accumulated other comprehensive loss — 432 20 452

Net current-period other comprehensive income

— 1,481 105 1,586

At December 31, 2024 $ — $ ( 16,561 ) $ ( 237 ) $ ( 16,798 )

The following amounts were reclassified out of accumulated other comprehensive loss into net income.

The amounts presented in parentheses indicate a decrease to net income on the Consolidated Statements of Income.

The reclassifications for the years ended December 31 were as follows:

2024 2023 Location on Consolidated

Statements of Income

(In thousands)

Reclassification adjustment for loss on derivative instruments included in net income $ — $ ( 96 ) Interest expense

— 15 Income taxes

Amortization of postretirement liability losses included in net periodic benefit credit ( 577 ) ( 320 ) Other income

145 78 Income taxes

( 432 ) ( 242 )

Reclassification adjustment on available-for-sale investments included in net income ( 25 ) ( 54 ) Other income

5 11 Income taxes

Under the performance condition for these PSAs, participants could earn from zero to 200 percent of the apportioned target grant of shares.

The performance condition was based on the Company's cumulative earnings per share growth.

The weighted average grant-date fair value per share for the PSAs applicable to this performance condition issued in 2025 was $ 16.83 .

A summary of the status of the PSAs for the year ended December 31, 2025, was as follows:

Number of Shares

Nonvested at beginning of period — $ —

296,128 17.03

Total reclassifications $ ( 452 ) $ ( 366 )

MDU Resources Group, Inc.

Vested shares

Nonvested at end of period 296,128 $ 17.03

Note 13 - Income Taxes

16 unchanged sentences

Total income tax expense $ 19,570 $ 17,589 $ 10,213

MDU Resources Group, Inc.

Components of deferred tax assets and deferred tax liabilities at December 31 were as follows:

12 unchanged sentences

Pension and postretirement 47,931 48,355

Purchased gas adjustment 20,441 34,618

Environmental compliance 17,260 16,221

Cost recovery mechanisms 18,109 19,245

Environmental compliance 17,173 17,260

Legal and environmental contingencies 6,399 6,300

Purchased gas adjustment 5,137 20,441

Other 23,695 19,931

2 unchanged sentences

Net deferred income tax liability $ 437,286 $ 441,320

As of both December 31, 2024 and 2023, the Company had various state income tax net operating loss carryforwards of $ 1.0 million and state income tax credit carryforwards, excluding alternative minimum tax credit carryforwards, of $ 31.6 million and $ 33.7 million, respectively.

As of December 31, 2025 and 2024, the Company had various state income tax net operating loss carryforwards of $ 819,000 and $ 1.0 million, respectively, and state income tax credit carryforwards, excluding alternative minimum tax credit carryforwards, of $ 28.5 million and $ 31.6 million, respectively.

The state income tax credit carryforwards are due to expire between 2027 and 2039.

Changes in tax regulations or assumptions regarding current and future taxable income could require additional valuation allowances in the future.

88 MDU Resources Group, Inc.

The following table reconciles the change in the net deferred income tax liability from December 31, 2023, to December 31, 2024, to deferred income tax expense:

The following table reconciles the change in the net deferred income tax liability from December 31, 2024, to December 31, 2025, to deferred income tax benefit:

(In thousands)

Change in net deferred income tax liability from the preceding table $ ( 4,034 )

Excess deferred income tax amortization ( 8,121 )

Effects of rate-regulated accounting ( 4,890 )

Deferred taxes associated with other comprehensive income 1

Deferred income tax expense for the period $ ( 16,078 )

Deferred income tax benefit for the period

96 MDU Resources Group, Inc.

Total income tax expense differs from the amount computed by applying the statutory federal income tax rate to income before taxes.

The reasons for this difference were as follows:

Year ended December 31, 2025

federal statutory tax rate $ 44,305 21.0

State and local income taxes, net of federal income tax effect * 2,917 1.4

Federal renewable energy credit ( 19,324 ) ( 9.2 )

Other ( 1,938 ) ( 0.9 )

Nontaxable or nondeductible Items ( 265 ) ( 0.1 )

Effects of rate-regulated accounting ( 5,169 ) ( 2.5 )

Other ( 956 ) ( 0.4 )

Total income tax expense and effective tax rate $ 19,570 9.3

* In 2025, state income taxes in Oregon and Montana made up the majority (greater than 50%) of the tax effect in this category.

Years ended December 31, 2024 2023

Amount % Amount % Amount %

(Dollars in thousands)

Amount % Amount %

Computed tax at federal statutory rate $ 41,719 21.0 $ 71,469 21.0

1 unchanged sentence

State income taxes, net of federal income tax 4,047 2.0 3,605 1.1

4,047 2.0 3,605 1.1 2,484 2.0

State investment tax credit, net of federal income tax 2,400 1.2 1,545 0.5

1 unchanged sentence

Federal renewable energy credit ( 16,871 ) ( 8.5 ) ( 15,175 ) ( 4.5 )

( 16,871 ) ( 8.5 ) ( 15,175 ) ( 4.5 ) ( 15,343 ) ( 12.4 )

Excess deferred income tax amortization ( 8,121 ) ( 4.1 ) ( 8,383 ) ( 2.5 )

6 unchanged sentences

The Company's effective tax rate for 2025 differs from the U.S.

federal statutory rate of 21 percent due primarily to the impact of credits and deductions provided by law and excess deferred income tax amortization.

federal statutory rate of 21 percent due primarily to the impact of credits and deductions provided by law and the effects of rate-regulated accounting, primarily the amortizations of excess deferred income taxes and deferred investment tax credits.

Income taxes paid (net of refunds) for the year ended December 31, 2025, was $ 30.8 million, consisting of $ 27.7 million in federal income taxes and $ 3.1 million in state income taxes.

Income taxes paid (net of refunds) in Montana of $ 1.8 million exceeded 5 percent of total income taxes paid (net of refunds).

The Company and its subsidiaries file income tax returns in the U.S.

4 unchanged sentences

The Company recognizes interest and penalties accrued relative to unrecognized tax benefits in income tax expense.

Note 16 - Cash Flow Information

Cash expenditures for interest and income taxes for the years ended December 31 were as follows:

2024 2023 2022

(In thousands)

Interest, net*

$ 108,242 $ 112,839 $ 49,036

Income taxes paid (refunded), net**

$ 43,572 $ 12,162 $ ( 27,884 )

* AFUDC - borrowed was $ 11.0 million, $ 10.0 million and $ 2.2 million for the years ended December 31, 2024, 2023 and 2022, respectively.

** Income taxes paid, including discontinued operations, were $ 80.9 million, $ 62.5 million and $ 26.4 million for the years ended December 31, 2024, 2023 and 2022, respectively.

Noncash investing and financing transactions at December 31 were as follows:

2024 2023 2022

(In thousands)

Property, plant and equipment additions in accounts payable $ 36,820 $ 46,364 $ 34,886

Right-of-use assets obtained in exchange for new operating lease liabilities $ 1,787 $ 2,265 $ 1,324

Debt for equity exchange of retained shares in Knife River

$ — $ 293,239 $ —

MDU Resources Group, Inc.

18 unchanged sentences

Discontinued operations includes the results of operations for Knife River and Everus and certain associated separation costs, including interest on certain debt facilities repaid in connection with the separations.

For the comparative periods below, Everus' operations are only reflected through October 2024 compared to the full year in 2023 and 2022 and Knife River's operations are only reflected through May 2023, compared to the full year in 2022.

For the comparative periods below, Everus' operations are only reflected through October 2024 compared to the full year in 2023 and Knife River's operations are only reflected through May 2023.

Discontinued operations also includes the supporting activities of Fidelity other than certain general and administrative costs and interest expense as described above.

14 unchanged sentences

Electric fuel and purchased power 158,995 — — — 158,995

141,148 — — — 141,148

Depreciation and amortization 69,608 104,976 32,124 — 206,708

2 unchanged sentences

External other income 7,470 15,792 3,488 1,599 28,349

8,205 25,509 5,850 1,803 41,367

Intersegment other income — — 243 4,992 5,235

— — 655 14,798 15,453

Interest expense:

2 unchanged sentences

Income tax expense (benefit) ( 9,578 ) 9,604 19,932 ( 388 ) 19,570

( 2,414 ) 7,974 17,470 ( 5,441 ) 17,589

Income (loss) from continuing operations 64,896 56,052 68,178 2,281 191,407

74,793 46,937 68,042 ( 8,699 ) 181,073

Discontinued operations, net of tax — — — ( 1,012 ) ( 1,012 )

1 unchanged sentence

Capital expenditures (a) $ 422,929 $ 298,553 $ 59,348 $ — $ 780,830

$ 110,812 $ 286,152 $ 126,806 $ 1,728 $ 525,498

Assets $ 1,976,912 (b)

$ 3,730,532 (b) $ 1,151,317 $ 180,057 (c)

Assets $ 2,367,067 (b) $ 3,909,046 (b) $ 1,196,959 $ 149,134 (c) $ 7,622,206

Property, plant and equipment $ 2,868,379 (b) $ 4,003,754 (b) $ 1,388,691 $ 4,148 $ 8,264,972

Accumulated depreciation and amortization

$ 716,736 (b)

$ 1,139,223 (b)

$ 351,045 $ 2,767 $ 2,209,771

Accumulated depreciation and amortization $ 734,674 (b) $ 1,194,279 (b) $ 373,020 $ 2,814 $ 2,304,787

(a) Capital expenditures include noncash transactions such as capital expenditure-related accounts payable and AFUDC totaling $( 10.8 ) million.

15 unchanged sentences

Electric fuel and purchased power 141,148 — — — 141,148

134,779 — — — 134,779

Depreciation and amortization 66,524 101,958 29,362 2,234 200,078

Taxes, other than income 17,605 76,042 12,175 394 106,216

Realized gain on tax-free exchange of the retained shares in Knife River — — — 186,556 186,556

Other income:

5 unchanged sentences

Income tax expense (benefit) ( 2,414 ) 7,974 17,470 ( 5,441 ) 17,589

( 1,019 ) 6,927 12,409 ( 8,104 ) 10,213

Income from continuing operations 74,793 46,937 68,042 ( 8,699 ) 181,073

71,559 48,520 47,375 162,663 330,117

Discontinued operations, net of tax — — — 100,035 100,035

1 unchanged sentence

Capital expenditures (a) $ 110,812 $ 286,152 $ 126,806 $ 1,728 $ 525,498

$ 109,805 $ 274,836 $ 115,903 $ ( 2,825 ) $ 497,719

Assets $ 1,955,644 (b)

$ 3,532,142 (b)

$ 1,045,704 $ 1,299,669 (c)

Property, plant and equipment

$ 2,369,039 (b)

$ 3,462,187 (b)

$ 1,218,387 $ 31,654 $ 7,081,267

Accumulated depreciation and amortization

$ 660,438 (b)

$ 1,068,037 (b)

$ 328,010 $ 19,890 $ 2,076,375

Assets $ 1,976,912 (b) $ 3,730,532 (b) $ 1,151,317 $ 180,057 (c) $ 7,038,818

Property, plant and equipment $ 2,480,816 (b) $ 3,731,093 (b) $ 1,338,006 $ 4,148 $ 7,554,063

Accumulated depreciation and amortization $ 716,736 (b) $ 1,139,223 (b) $ 351,045 $ 2,767 $ 2,209,771

(a) Capital expenditures include noncash transactions such as capital expenditure-related accounts payable and AFUDC totaling $ 7.1 million.

15 unchanged sentences

Electric fuel and purchased power 134,779 — — — 134,779

119,405 — — — 119,405

Depreciation and amortization 64,253 95,300 26,811 4,086 190,450

Taxes, other than income 16,695 75,207 10,822 409 103,133

Realized gain on tax-free exchange of the retained shares in Knife River

— — — 186,556 186,556

Other income:

5 unchanged sentences

Income tax expense (benefit) ( 1,019 ) 6,927 12,409 ( 8,104 ) 10,213

( 5,420 ) 7,805 10,522 ( 6,712 ) 6,195

Income (loss) from continuing operations 71,559 48,520 47,375 162,663 330,117

57,077 45,171 36,194 ( 21,190 ) 117,252

Discontinued operations, net of tax — — ( 457 ) 85,047 84,590

1 unchanged sentence

Capital expenditures (a) $ 109,805 $ 274,836 $ 115,903 $ ( 2,825 ) $ 497,719

$ 133,970 $ 240,064 $ 61,923 $ 2,272 $ 438,229

Assets $ 1,856,258 (b)

$ 3,214,452 (b)

$ 961,893 $ 3,628,178 (c)

Property, plant and equipment

$ 2,276,613 (b)

$ 3,208,059 (b)

$ 1,108,141 $ 36,705 $ 6,629,518

Accumulated depreciation and amortization

$ 625,813 (b)

$ 1,009,788 (b)

$ 308,516 $ 19,143 $ 1,963,260

Assets $ 1,955,644 (b) $ 3,532,142 (b) $ 1,045,704 $ 1,299,669 (c) $ 7,833,159

Property, plant and equipment $ 2,369,039 (b) $ 3,462,187 (b) $ 1,218,387 $ 31,654 $ 7,081,267

Accumulated depreciation and amortization $ 660,438 (b) $ 1,068,037 (b) $ 328,010 $ 19,890 $ 2,076,375

(a) Capital expenditures include noncash transactions such as capital expenditure-related accounts payable and AFUDC totaling $( 13.6 ) million.

16 unchanged sentences

MDU Resources Group, Inc.

Form 10-K 101

Note 15 - Employee Benefit Plans

10 unchanged sentences

Effective January 1, 2013, post-65 coverage was replaced by a fixed-dollar subsidy for retirees and spouses to be used to purchase individual insurance through a healthcare exchange.

In connection with the previously discussed separation of Knife River on May 31, 2023, Knife River's pension plan, including the associated assets and liabilities, was transferred to Knife River and therefore is no longer reflected as part of the Company.

Also in connection with the separation, a remeasurement of the Company's postretirement plan and the Company's unfunded, non-qualified defined benefit plan were performed and the applicable liabilities from the plans relating to transferring employees were transferred to Knife River.

Changes in benefit obligation and plan assets and amounts recognized in the Consolidated Balance Sheets at December 31 were as follows:

8 unchanged sentences

Plan participants' contributions — — 384 412

Actuarial (gain) loss

Actuarial loss (gain)

3,080 ( 11,040 ) ( 355 ) ( 3,420 )

25 unchanged sentences

For more information on regulatory assets and liabilities, see Note 6.

In 2024, the actuarial gain recognized in the benefit obligation was primarily the result of an increase in the discount rate.

In 2025, the actuarial loss recognized in the benefit obligation was primarily the result of a decrease in the discount rate.

In 2024, the actuarial gain recognized in the benefit obligation was primarily the result of an increase in the discount rate.

For more information on the discount rates, see the table below.

1 unchanged sentence

The market-related value of assets is determined using a five-year average of assets.

The pension plans all have accumulated benefit obligations in excess of plan assets.

All but one of the pension plans have accumulated benefit obligations in excess of plan assets.

The projected benefit obligation, accumulated benefit obligation and fair value of plan assets for these plans at December 31 were as follows:

22 unchanged sentences

Other changes in plan assets and benefit obligations recognized in accumulated comprehensive loss:

Net loss (gain)

Net (gain) loss

( 14 ) 401 187 ( 119 ) 71 ( 604 )

1 unchanged sentence

Amortization of prior service credit — — — 49 45 78

Reclassification of postretirement liability adjustment from regulatory asset — — 5,343 — — ( 992 )

Total recognized in accumulated other comprehensive loss ( 414 ) 42 ( 105 ) 12 246 ( 418 )

Other changes in plan assets and benefit obligations recognized in regulatory assets or liabilities:

Net loss (gain)

Net (gain) loss

( 1,523 ) 3,520 1,826 ( 2,186 ) ( 472 ) ( 107 )

1 unchanged sentence

Amortization of prior service credit

Reclassification of postretirement liability adjustment from regulatory asset — — ( 5,343 ) — — 992

— — — 1,109 1,273 1,273

Total recognized in regulatory assets or liabilities ( 5,897 ) ( 270 ) ( 975 ) ( 839 ) 959 1,470

1 unchanged sentence

MDU Resources Group, Inc.

Form 10-K 103

Weighted average assumptions used to determine benefit obligations at December 31 were as follows:

17 unchanged sentences

9.5 %/ 7.00 %

8.5 %/ 6.25 %

Health care cost trend rate - ultimate 4.5 % 4.5 %

18 unchanged sentences

2031-2035 $ 95,250 $ 13,410 $ 15

104 MDU Resources Group, Inc.

Outside investment managers manage the Company's pension and postretirement assets.

5 unchanged sentences

The Company's practice is to periodically review and rebalance asset categories based on its targeted asset allocation percentage policy.

96 MDU Resources Group, Inc.

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the measurement date.

9 unchanged sentences

Government securities are valued mainly using other observable inputs, including benchmark yields, reported trades, broker/dealer quotes, bids, offers, to be announced prices, future cash flows and other reference data.

The estimated fair value of the pension plans' Level 2 pooled separate accounts are determined using observable inputs in active markets or the net asset value of shares held at year end, or other observable inputs.

Some of these securities are valued using pricing from outside sources.

All investments measured at net asset value in the tables that follow are invested in commingled funds, separate accounts or common collective trusts which do not have publicly quoted prices.

2 unchanged sentences

Though the Company believes the methods used to estimate fair value are consistent with those used by other market participants, the use of other methods or assumptions could result in a different estimate of fair value.

The fair value of the Company's pension plans' assets (excluding cash) by class were as follows:

MDU Resources Group, Inc.

Form 10-K 105

The fair value of the Company's pension plans' assets by class were as follows:

Fair Value Measurements

10 unchanged sentences

Government securities 36,744 26,281 — 63,025

Investments measured at net asset value (b) — — — 260

Total assets measured at fair value $ 123,182 $ 108,490 $ — $ 231,672

(a) Collective and mutual funds invest approximately 35 percent in corporate bonds, 30 percent in U.S.

Government securities, 17 percent in other investments, 15 percent in common stock of international companies, 9 percent in common stock of large-cap and mid-cap U.S.

companies, and 1 percent cash and cash equivalents.

(b) In accordance with ASC 820 - Fair Value Measurements, certain investments that were measured at net asset value per share (or its equivalent) have not been classified in the fair value hierarchy.

The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the line items presented in the Consolidated Balance Sheets.

MDU Resources Group, Inc.

Government securities, 13 percent in common stock of international companies, 12 percent in common stock of large-cap and mid-cap U.S.

companies, and 10 percent in other investments.

Fair Value Measurements

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Total assets measured at fair value $ 106,391 $ 123,975 $ — $ 230,626

(a) Collective and mutual funds invest approximately 51 percent in corporate bonds, 15 percent in common stock of international companies, 11 percent in common stock of large-cap and mid-cap U.S.

companies, 7 percent cash and cash equivalents, 7 percent in U.S.

Government securities and 9 percent in other investments.

(a) Collective and mutual funds invest approximately 39 percent in corporate bonds, 19 percent in U.S.

Government securities, 17 percent in other investments, 15 percent in common stock of international companies, 9 percent in common stock of large-cap and mid-cap U.S.

companies, and 1 percent cash and cash equivalents.

(b) In accordance with ASC 820 - Fair Value Measurements, certain investments that were measured at net asset value per share (or its equivalent) have not been classified in the fair value hierarchy.

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The fair value of the Company's other postretirement benefit plans' assets (excluding cash) by asset class were as follows:

106 MDU Resources Group, Inc.

The fair value of the Company's other postretirement benefit plans' assets by asset class were as follows:

Fair Value Measurements

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Insurance contract (a) — 74,655 — 74,655

Plan assets (b)

Total assets measured at fair value $ 2,833 $ 80,168 $ — $ 83,409

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companies and 1 percent in other investments.

98 MDU Resources Group, Inc.

(b) Deposits held by service providers or claims processors.

Fair Value Measurements

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Total assets measured at fair value $ 2,880 $ 75,885 $ — $ 78,765

(a) The insurance contract invests approximately 60 percent in corporate bonds, 16 percent in common stock of large-cap U.S.

companies, 15 percent in U.S.

Government securities, 5 percent in common stock of small-cap U.S.

(a) The insurance contract invests approximately 41 percent in corporate bonds, 28 percent in U.S.

Government securities, 19 percent in common stock of large-cap U.S.

companies, 6 percent in common stock of small-cap U.S.

companies and 6 percent in other investments.

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Accumulated benefit obligation $ 49,598 $ 52,007

MDU Resources Group, Inc.

Form 10-K 107

The components of net periodic benefit cost are included in other income on the Consolidated Statements of Income.

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Nonqualified benefits $ 5,620 $ 5,810 $ 5,550 $ 5,170 $ 4,560 $ 19,870

MDU Resources Group, Inc.

In 2012, the Company established a nonqualified defined contribution plan for certain key management employees.

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A new nonqualified defined contribution plan was adopted in 2020, effective January 1, 2021, to replace the plan originally established in 2012 with similar provisions.

Expenses incurred under these plans for 2024, 2023 and 2022 were $ 4.0 million, $ 2.7 million and $ 538,000 , respectively.

Expenses incurred under these plans for 2025, 2024 and 2023 were $ 4.7 million, $ 4.0 million and $ 2.7 million, respectively.

The amount of investments that the Company anticipates using to satisfy obligations under these plans at December 31 was as follows:

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The Company sponsors a defined contribution plan for eligible employees and the costs incurred under this plan were $ 19.1 million in 2025, $ 10.7 million in 2024 and $ 17.0 million in 2023.

108 MDU Resources Group, Inc.

Multiemployer plans

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MDU Resources Group, Inc.

Form 10-K 109

Note 16 - Jointly Owned Facilities

The consolidated financial statements include the Company's ownership interests in three coal-fired electric generating facilities (Big Stone Station, Coyote Station and Wygen III) and two major transmission lines (BSSE and JETx).

Each owner of the jointly owned facilities is responsible for financing its investment.

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and taxes, other than income) in the Consolidated Statements of Income.

In December 2025, the Company completed the acquisition of a 49 percent undivided ownership interest in Badger Wind Farm for approximately $ 294.0 million, located near Wishek, ND, and placed the asset in service.

The purchase was recorded as an asset acquisition to Net, property, plant and equipment on the Company's Consolidated Balance Sheet.

The completed transaction secures 122.5 MW of the project's total 250 MW generation capacity for the Company and follows the NDPSC's Advance Determination of Prudence and Certificate of Public Convenience and Necessity approvals, confirming the project is a prudent, cost-effective investment for customers.

The Company previously executed a PPA for 150 MW of output from the project, which included the option to purchase the 49 percent ownership interest.

With the closing now complete, the PPA has been reduced to 27.5 MW.

At December 31, the Company's share of the cost of utility plant in service, construction work in progress and related accumulated depreciation for the jointly owned facilities was as follows:

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(In thousands)

Badger Wind Farm:

Utility plant in service $ 299,823 $ —

Less accumulated depreciation — —

$ 299,823 $ —

Big Stone Station:

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110 MDU Resources Group, Inc.

Form 10-K 101

Note 20 - Regulatory Matters

The Company regularly reviews the need for electric and natural gas rate changes in each of the jurisdictions in which service is provided.

The Company files for rate adjustments to seek recovery of operating costs and capital investments, as well as reasonable returns as allowed by regulators.

Certain regulatory proceedings and cases may also contain recurring mechanisms that can have an annual true-up.

Examples of these recurring mechanisms include:

infrastructure riders, transmission trackers, renewable resource cost adjustment riders, as well as weather normalization and decoupling mechanisms.

The following paragraphs summarize the Company's significant open regulatory proceedings and cases by jurisdiction.

On July 15, 2024, Montana-Dakota filed a request with the MTPSC for a natural gas general rate increase of approximately $ 9.4 million annually or 11.1 percent above current rates.

The requested increase is primarily to recover investments in system upgrades and pipeline replacement projects enhancing the reliability, safety and integrity of the natural gas system, as well as increased costs to operate and maintain that system.

On October 15, 2024, the MTPSC denied Montana-Dakota's request for an interim rate increase of approximately $ 8.0 million annually or 10.2 percent above current rates.

On October 25, 2024, Montana-Dakota filed a motion for reconsideration of the interim rate increase.

On January 14, 2025, the MTPSC approved an interim increase of approximately $ 7.7 million with interim rates effective on and after February 1, 2025.

On November 1, 2023, Montana-Dakota filed a request with the NDPSC for a natural gas general rate increase of approximately $ 11.6 million annually or 7.5 percent above current rates.

On December 13, 2023, the NDPSC approved an interim rate increase of approximately $ 10.1 million annually or 6.5 percent above current rates, subject to refund, for service rendered on and after January 1, 2024.

On September 16, 2024, an all-party settlement agreement was filed reflecting an annual revenue increase of $ 9.4 million or 6.1 percent overall.

The reduction from the original filing includes lower incentives and a decreased return on equity.

On November 7, 2024, the NDPSC approved the settlement with rates effective on and after December 1, 2024.

Montana-Dakota has a renewable resource cost adjustment rate tariff that allows for annual adjustments for recent projected capital costs and related expenses for projects determined to be recoverable under the tariff.

On November 1, 2024, Montana-Dakota filed an annual update to its renewable resource cost adjustment requesting to recover a revenue requirement of approximately $ 18.3 million annually.

The update reflects a decrease of approximately $ 2.8 million annually from the revenues currently included in rates.

The NDPSC approved the renewable resource cost adjustment on January 22, 2025, with rates effective February 1, 2025.

On March 29, 2024, Cascade filed a request with the WUTC for a multi-year natural gas general rate increase of $ 43.8 million or 11.6 percent effective March 1, 2025 and $ 11.7 million or 2.8 percent to be effective March 1, 2026.

Multi-year filings are now required by Washington law that went into effect on January 1, 2022.

The requested increase is primarily to recover infrastructure investments necessary to provide safe and reliable service and higher operating costs due to inflation.

On December 11, 2024, a multi-party settlement agreement was filed reflecting rate increases of $ 29.8 million or 7.9 percent proposed to be effective March 1, 2025, and $ 10.8 million or 2.6 percent proposed to be effective March 1, 2026.

On October 31, 2024, Montana-Dakota filed a request with the WYPSC for a natural gas general rate increase of approximately $ 2.6 million annually or 14.0 percent above current rates.

This matter is pending before the WYPSC.

On August 29, 2024, Montana-Dakota filed an update to its transmission formula rate under the MISO tariff for its multi-value project and network upgrade changes for $ 19.7 million.

Rates were effective January 1, 2025.

102 MDU Resources Group, Inc.

Note 17 - Commitments and Contingencies

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At December 31, 2025 and 2024, the Company accrued liabilities which have not been discounted of $ 26.1 million and $ 24.1 million, respectively.

At December 31, 2024 and 2023, the Company also recorded corresponding insurance receivables of $ 24,000 and $ 152,000 , respectively, and regulatory assets of $ 22.9 million and $ 21.6 million, respectively, related to the accrued liabilities.

The accruals are for contingencies resulting from litigation and environmental matters.

At December 31, 2025 and 2024, the Company also recorded corresponding receivables of $ 1.6 million and $ 24,000 , respectively, and regulatory assets of $ 23.2 million and $ 22.9 million, respectively, related to the accrued liabilities.

The accruals are for contingencies resulting from litigation, regulatory and environmental matters.

This includes amounts that have been accrued for matters discussed in Environmental matters within this note.

The Company will continue to monitor each matter and adjust accruals as might be warranted based on new information and further developments.

In January 2026, the Company received a final order on a regulatory commission complaint for $ 2.0 million, with $ 250,000 suspended on the condition that the Company complete additional compliance actions outlined in the order.

At December 31, 2025, the Company had $ 1.75 million included in accrued liabilities for this matter.

Management believes that the outcomes with respect to probable and reasonably possible losses in excess of the amounts accrued, net of insurance recoveries, while uncertain, either cannot be estimated or will not have a material effect upon the Company's financial position, results of operations or cash flows.

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For more information, see Note 6.

Demand has been made of Montana-Dakota to participate in investigation and remediation of environmental contamination at a site in Missoula, Montana.

The site operated as a former manufactured gas plant from approximately 1907 to 1938 when it was converted to a butane-air plant that operated until 1956.

Montana-Dakota or its predecessors owned or controlled the site for a period of the time it operated as a manufactured gas plant and Montana-Dakota operated the butane-air plant from 1940 to 1951, at which time it sold the plant.

There are no documented wastes or by-products resulting from the mixing or distribution of butane-air gas.

Preliminary assessment of a portion of the site provided a recommended remedial alternative for that portion of approximately $ 560,000 .

However, the recommended remediation would not address any potential contamination to adjacent parcels that may be impacted from historic operations of the manufactured gas plant.

An environmental assessment, which was started in 2020 and is still underway, is estimated to cost approximately $ 2.0 million.

A claim was made against Montana-Dakota for contamination at a manufactured gas plant site in Missoula, Montana.

Montana-Dakota and another party agreed to voluntarily investigate and remediate the site and that Montana-Dakota will pay two-thirds of the costs for further investigation and remediation of the site.

Montana-Dakota has accrued costs of $ 645,000 for the remediation and investigation costs and has incurred costs of $ 1.2 million as of December 31, 2024.

Montana-Dakota received notice from a prior insurance carrier that it will participate in payment of defense costs incurred in relation to the claim.

On December 9, 2021, Montana Dakota filed an application with the MTPSC for deferred accounting treatment for costs associated with the investigation and remediation of the site.

The MTPSC approved the application for deferred accounting treatment as requested on July 26, 2022.

A claim was made against Cascade for contamination at the Bremerton Gasworks Superfund Site in Bremerton, Washington, which was received in 1997.

A preliminary investigation has found soil and groundwater at the site contain impacts requiring further investigation and cleanup.

The EPA conducted a Targeted Brownfields Assessment of the site and released a report summarizing the results of that assessment in August 2009.

The assessment confirmed that impacts have affected soil and groundwater at the site, as well as sediments in the adjacent Port Washington Narrows.

An environmental assessment was started in 2020 and is still underway.

In July 2022, the MTPSC approved Montana-Dakota's application for deferred accounting treatment of costs associated with the investigation and remediation of the site.

In 1997, a claim was made against Cascade for contamination at the Bremerton Gasworks Superfund Site in Bremerton, Washington.

The EPA conducted a Targeted Brownfields Assessment of the site which confirmed contamination at the site and in the adjacent Port Washington Narrows.

In April 2010, the Washington DOE issued notice it considered Cascade a PRP for hazardous substances at the site.

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Cascade entered into an administrative settlement agreement and consent order with the EPA regarding the scope and schedule for a remedial investigation and feasibility study for the site.

Current estimates for the cost to complete the remedial investigation and feasibility study are approximately $ 16.0 million of which $ 11.7 million has been incurred as of December 31, 2024.

Based on the site investigation, preliminary remediation alternative costs were provided by consultants in August 2020.

The preliminary information received through the completion of the data report allowed for the projection of possible costs for a variety of site configurations, remedial measures and potential natural resource damage claims of between $ 13.6 million and $ 71.5 million.

At December 31, 2024, Cascade has accrued $ 4.3 million for the remedial investigation and feasibility study, as well as $ 17.5 million for remediation of this site.

The preliminary information received through the completion of the data report in August 2020, allowed for the projection of possible costs for a variety of site configurations, remedial measures and potential natural resource damage claims between $ 13.6 million and $ 71.5 million.

The accrual for remediation costs will be reviewed and adjusted, if necessary, after the completion of the feasibility study.

In April 2010, Cascade filed a petition with the WUTC for authority to defer the costs incurred in relation to the environmental remediation of this site.

The WUTC approved the petition in September 2010, subject to conditions set forth in the order.

In September 2010, the WUTC approved the petition filed by Cascade regarding deferral of remediation costs, subject to conditions set forth in the order.

A significant portion of the costs incurred to date have been recovered by insurance.

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Form 10-K 111

A claim was made against Cascade for impacts at a site in Bellingham, Washington.

Cascade received notice from a party in May 2008 that Cascade may be a PRP, along with other parties, for impacts from a manufactured gas plant owned by Cascade and its predecessor from about 1946 to 1962.

A claim was made against Cascade for impacts at a manufactured gas plant site in Bellingham, Washington.

Cascade received notice from a party in May 2008 that Cascade may be a PRP, along with other parties.

Other PRPs reached an agreed order and work plan with the Washington DOE for completion of a remedial investigation and feasibility study for the site.

A feasibility study prepared for one of the PRPs in March 2018 identifies five cleanup action alternatives for the site with estimated costs ranging from $ 8.0 million to $ 20.4 million with a selected preferred alternative having an estimated total cost of $ 9.3 million.

The other PRPs developed a cleanup action plan and completed public review in 2020.

The development of the remediation design is underway, with the Pre-Remedial Design Investigation Data Report and Engineering Design Report submitted to Washington Ecology in June 2023 and November 2024, respectively.

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Cascade believes its proportional share of any liability will be relatively small in comparison to other PRPs.

The plant manufactured gas from coal between approximately 1890 and 1946.

In 1946, shortly after Cascade's predecessor acquired the plant, the plant converted to a propane-air gas facility.

There are no documented wastes or by-products resulting from the mixing or distribution of propane-air gas.

Cascade has recorded an accrual for this site for an amount that is not material.

1 unchanged sentence

To the extent these claims are not covered by insurance, the Company intends to seek recovery of remediation costs through its natural gas rates charged to customers.

Details of the estimates for remedial investigations, feasibility studies and remediation, as well as incurred and accrued costs at these manufactured gas plant sites were as follows:

December 31, 2025 Total Estimated Costs

Total Incurred Costs

Total Accrued Costs

(In thousands)

Montana-Dakota - Missoula MGP (a)

$ 2,042 $ 1,232 $ 810

Cascade - Bremerton MGP (b)

$ 34,730 $ 12,772 $ 21,958

(a) Total estimated, incurred and accrued costs for Montana-Dakota's two-thirds share of the ongoing remedial investigation

and remediation of the Missoula site.

(b) Total estimated, incurred and accrued costs for the ongoing remedial investigation, feasibility study and remediation of

the Bremerton site.

Purchase commitments

4 unchanged sentences

Certain of these contracts are subject to variability in volume and price.

The Company's purchase commitments decreased from those reported in the 2024 Annual Report due to a decrease in electric supply contracts as a result of the Company's purchase of a 49 percent undivided ownership interest Badger Wind Farm on December 31, 2025.

The commitment terms vary in length, up to 34 years.

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These commitments were not reflected in the Company's consolidated financial statements.

Amounts purchased under various commitments for the years ended December 31, 2024, 2023 and 2022, were $ 841.7 million, $ 1.0 billion and $ 870.6 million, respectively.

Amounts purchased under various commitments for the years ended December 31, 2025, 2024 and 2023, were $ 873.5 million, $ 841.7 million and $ 1.0 billion, respectively.

The Company and certain subsidiaries have outstanding letters of credit to third parties related to insurance policies and other agreements, some of which are guaranteed by other subsidiaries of the Company.

At December 31, 2024, the fixed maximum amounts guaranteed under these letters of credit aggregated $ 14.3 million.

The amounts of scheduled expiration of the maximum amounts guaranteed under these letters of credit aggregate to $ 14.3 million in 2025.

At December 31, 2025, the fixed maximum amounts guaranteed under these letters of credit aggregated $ 3.2 million, all of which have scheduled expiration of the maximum amounts in 2026.

There were no amounts outstanding under the previously mentioned letters of credit at December 31, 2025.

3 unchanged sentences

At December 31, 2025, approximately $ 13.4 million of surety bonds were outstanding, which were not reflected on the Consolidated Balance Sheet.

112 MDU Resources Group, Inc.

Most of the leases the Company enters into are for equipment, buildings, easements and vehicles as part of their ongoing operations.

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To date, the Company does not have any residual value guarantee amounts probable of being owed to a lessor, financing leases or material agreements with related parties.

104 MDU Resources Group, Inc.

The following tables provide information on the Company's operating leases at and for the years ended December 31:

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Total operating lease liabilities*

*The Company's increase in operating lease liabilities in 2025 is primarily due to the Company's 49 percent share of Badger Wind Farm leases.

MDU Resources Group, Inc.

Form 10-K 113

Lessor accounting The Company leases certain equipment to third parties through its utility businesses, which are considered short-term operating leases with terms of less than 12 months.

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114 MDU Resources Group, Inc.

Form 10-K 105

Note 22 - Subsequent Events

On February 13, 2025, Montana-Dakota entered into a definitive purchase and sale agreement with Badger Wind, LLC, a subsidiary of Orsted Onshore North America, LLC.

Pursuant to the terms of the agreement, Montana-Dakota will purchase a 49 percent undivided ownership interest in a wind project being constructed and located in North Dakota that is anticipated to have a net generating capacity of approximately 250 MW for a purchase price of $ 294.0 million, which would represent 122.5 MW of wind generation to be owned by Montana-Dakota.

The purchase agreement is contingent on regulatory approval from the NDPSC.

This transaction would reduce Montana-Dakota's purchase requirements under the existing power purchase agreement with Badger Wind, LLC, dated November 4, 2024.

106 MDU Resources Group, Inc.

Changes in and Disagreements With Accountants on Accounting and Financial Disclosure

Compared sentence by sentence after normalising whitespace, quotation marks, case and digits, so re-formatting and restated figures do not read as changed language. Wording changes appear as one removal and one addition. The current filing and the prior one are authoritative.

What changed 10-K

Item 8. Financial Statements and Supplementary Data