Material Agreement (Form 8-K)

As previously disclosed, on December 3, 2025, MDU Resources Group, Inc. (the "Company") entered into an Underwriting Agreement (the "Underwriting Agreement") with Wells Fargo Securities, LLC, BofA Securities, Inc. and J.P. Morgan Securities, LLC, as representatives of the several underwriters named therein (the "Underwriters"), Wells Fargo Bank, National Association, Bank of America, N.A. and JPMorgan Chase Bank, National Association, New York Branch (the "Forward Purchasers"), and Wells Fargo Securities, LLC, BofA Securities, Inc. and J.P. Morgan Securities, LLC, as forward sellers (in such capacities, the "Forward Sellers"), with respect to the offering and sale in an underwritten public offering by the Underwriters (the "Offering") of an aggregate of 10,152,284 shares (the "Forward Shares") of the Company's common stock, par value $1.00 per share (the "Common Stock"). All of the Forward Shares were borrowed from third parties and sold by the Forward Sellers to the Underwriters. In addition, the Underwriters were granted a 30-day option to purchase from time to time all or any part of 1,522,842 additional shares of Common Stock on the same terms.

In addition, as previously disclosed, on December 3, 2025, the Company entered into separate forward sale agreements (the "Forward Sale Agreements") with each of the Forward Purchasers, relating to the Forward Shares, to be borrowed from third parties and sold by the Forward Sellers to the Underwriters.

On December 23, 2025, the Underwriters exercised in full their option to purchase an additional 1,522,842 shares of Common Stock (the "Additional Forward Shares") pursuant to the Underwriting Agreement and, in connection therewith, the Company entered into separate additional forward sale agreements with each of the Forward Purchasers, relating to an aggregate of 1,522,842 shares of Common Stock (the "Additional Forward Sale Agreements"), on terms substantially similar to those contained in the Forward Sale Agreements.

On December 26, 2025, as contemplated by the Additional Forward Sale Agreements, the Forward Sellers borrowed the Additional Forward Shares from third parties and the Forward Sellers sold all such Additional Forward Shares in connection with the Additional Forward Sale Agreements to the Underwriters pursuant to the Underwriting Agreement.

The Additional Forward Sale Agreements provide for settlement on a settlement date or dates to be specified at the Company's discretion by December 6, 2027. On a settlement date or dates, if the Company decides to physically settle the Additional Forward Sale Agreements, the Company will issue shares of Common Stock to the Forward Purchasers at the then-applicable forward sale price. The forward sale price will initially be $18.90 per share, which is the price at which the Underwriters have agreed to buy the shares of Common Stock pursuant to the Underwriting Agreement. The Additional Forward Sale Agreements provide that the initial forward sale price will be subject to adjustment based on a floating interest rate factor equal to the overnight bank funding rate less a spread, and will be subject to decrease on each of certain dates specified in the Additional Forward Sale Agreements by amounts related to expected dividends on shares of the Common Stock during the term of the Additional Forward Sale Agreements. If the overnight bank funding rate is less than the spread on any day, the interest rate factor will result in a daily reduction of the forward sale price. The forward sale price will also be subject to decrease if the cost to a Forward Seller of borrowing the number of shares of the Common Stock underlying the applicable Additional Forward Sale Agreement exceeds a specified amount.

Before the issuance of the shares of Common Stock, if any, upon settlement of the Additional Forward Sale Agreements, the Company expects that the shares issuable upon settlement of the Additional Forward Sale Agreements will be reflected in the Company's diluted earnings per share calculations using the treasury stock method. Under this method, the number of shares of the Common Stock used in calculating diluted earnings per share is deemed to be increased by the excess, if any, of the number of shares of the Common Stock that would be issued upon full physical settlement of the Additional Forward Sale Agreements over the number of shares of the Common Stock that could be purchased by the Company in the market (based on the average market price of the Common Stock during the applicable reporting period) using the proceeds receivable upon full physical settlement (based on the adjusted forward sale price at the end of the applicable reporting period). Consequently, the Company anticipates there will be no dilutive effect on the Company's earnings per share except during periods when the average market price of shares of the Common Stock is above the applicable adjusted forward sale price, which is initially $18.90 per share, subject to increase or decrease based on the overnight bank funding rate, less a spread, and subject to decrease by amounts related to expected dividends on shares of the Common Stock during the term of the Additional Forward Sale Agreements.