Company Update

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K/A (Amendment No. 1) CURRENT REPORT PURSUANT TO SECTION 13 OR 15 (d) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): June 24, 2016 MDU Resources Group, Inc. (Exact name of registrant as specified in its charter) Delaware 1-3480 41-0423660 (State or other jurisdiction of (Commission File Number) (I.R.S. Employer Identification No.)   incorporation)     1200 West Century Avenue P.O. Box 5650 Bismarck, North Dakota 58506-5650 (Address of principal executive offices) (Zip Code) Registrant’s telephone number, including area code (701) 530-1000 Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:   q Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)   q Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)   q Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))   q Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))      1 Explanatory Note: On June 28, 2016, MDU Resources Group, Inc. (the “Company”) filed a Current Report on Form 8-K (the “Form 8-K”) to report a number of matters in connection with the sale of Dakota Prairie Refining, LLC. The Company is filing this amendment to the Form 8-K to include certain exhibits and to provide unaudited pro forma consolidated financial information that was inadvertently omitted from the Form 8-K. Item 9.01. Financial Statements and Exhibits. (b)   Pro Forma Financial Information.   Ÿ Unaudited pro forma consolidated balance sheet of the Company as of March 31, 2016.   Ÿ Unaudited pro forma consolidated statements of income of the Company for the three months ended March 31, 2016 and the years ended December 31, 2015, 2014 and 2013.   Ÿ Notes to the unaudited pro forma consolidated financial statements. (d)   Exhibits.     2.1* Membership Interest Purchase Agreement, dated as of June 24, 2016, between WBI Energy, Inc. and Tesoro Refining & Marketing Company LLC.     2.2+ Purchase and Sale Agreement, dated as of June 9, 2016, by and among Calumet North Dakota, LLC, WBI Energy, Inc., and, as applicable, MDU Resources Group, Inc., Centennial Energy Holdings, Inc., and Calumet Specialty Products Partners, L.P.     2.3 Amendment No. 1 to Purchase and Sale Agreement, dated as of June 9, 2016, by and among Calumet North Dakota, LLC, WBI Energy, Inc., and, as applicable, MDU Resources Group, Inc., Centennial Energy Holdings, Inc., and Calumet Specialty Products Partners, L.P.     99.1 Unaudited pro forma consolidated financial information.           * Certain schedules and exhibits have been omitted from Exhibit 2.1 pursuant to Item 601(b)(2) of Regulation S-K. The Company hereby undertakes to furnish supplemental copies of any of the omitted schedules and exhibits upon request by the Securities and Exchange Commission; provided, however, that the Company may request confidential treatment pursuant to Rule 24b-2 of the Exchange Act for any schedules or exhibits so furnished. The Exhibit Index to this Form 8-K/A lists the omitted schedules and exhibits. + Certain schedules and exhibits have been omitted from Exhibit 2.2 pursuant to Item 601(b)(2) of Regulation S-K. The Company hereby undertakes to furnish supplemental copies of any of the omitted schedules and exhibits upon request by the Securities and Exchange Commission; provided, however, that the Company may request confidential treatment pursuant to Rule 24b-2 of the Exchange Act for any schedules or exhibits so furnished. The Exhibit Index to this Form 8-K/A lists the omitted schedules and exhibits.         2 SIGNATURE Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this amendment to be signed on its behalf by the undersigned hereunto duly authorized. Date: July 20, 2016   MDU RESOURCES GROUP, INC.           By: /s/ Doran N. Schwartz     Doran N. Schwartz     Vice President and        Chief Financial Officer 3 EXHIBIT INDEX Exhibit Number Description of Exhibit 2.1*   Membership Interest Purchase Agreement, dated as of June 24, 2016, between WBI Energy, Inc. and Tesoro Refining & Marketing Company LLC. 2.2+   Purchase and Sale Agreement, dated as of June 9, 2016, by and among Calumet North Dakota, LLC, WBI Energy, Inc., and, as applicable, MDU Resources Group, Inc., Centennial Energy Holdings, Inc., and Calumet Specialty Products Partners, L.P. 2.3   Amendment No. 1 to Purchase and Sale Agreement, dated as of June 9, 2016, by and among Calumet North Dakota, LLC, WBI Energy, Inc., and, as applicable, MDU Resources Group, Inc., Centennial Energy Holdings, Inc., and Calumet Specialty Products Partners, L.P. 99.1   Unaudited pro forma consolidated financial information. * Certain schedules and exhibits have been omitted from Exhibit 2.1 pursuant to Item 601(b)(2) of Regulation S-K. The Company hereby undertakes to furnish copies of the omitted schedules and exhibits upon request by the Securities and Exchange Commission; provided, however, that the Company may request confidential treatment pursuant to Rule 24b-2 of the Exchange Act for any schedules or exhibits so furnished.   Omitted Schedules and Exhibits   Schedule 1.3          Working Capital Statement   Schedule 2.2(a)(ii)     Purchaser Account Information   Schedule 2.2(a)(iii)     Escrow Account Information   Schedule 2.2(a)(ix)     Indebtedness   Schedule 2.2(a)(xv) Governmental Authorizations and Third-Party Authorizations and Consents   Schedule 2.2(b)(i)      Seller Account Information   Schedule 3.2(a)     No Conflicts   Schedule 3.2(b)     Consents of any Governmental Authority   Schedule 3.3(a)      Ownership and Control   Schedule 3.6          No Undisclosed Liabilities   Schedule 3.7          Absence of Certain Changes and Events   Schedule 3.8      Tax Matters   Schedule 3.8(b)     Tax Returns   Schedule 3.9     Litigation   Schedule 3.10     Compliance with Laws   Schedule 3.11(a) Governmental Authorizations   Schedule 3.11(b)      Compliance with Governmental Authorizations   Schedule 3.12      Environmental Matters   Schedule 3.13(a)      Real Property   Schedule 3.13(d)      Violations Regarding Real Property and Improvements   Schedule 3.13(e)      Other Real Property Matter   Schedule 3.13(f)      Real Property Documents Modifications and Defaults   Schedule 3.13(h)      Real Property Notices and Consents 4   Schedule 3.13(i)      Real Property Options or Rights of First Refusal   Schedule 3.14(a)(i)      Trademarks   Schedule 3.14(d)(i)      Third Party Software   Schedule 3.15(a)      Title to Assets   Schedule 3.16(a) Benefits Plans   Schedule 3.16(i) Payments under Benefits Plans   Schedule 3.17(a)     Company Employees   Schedule 3.18     Insurance   Schedule 3.19(a)     Agreement List & Status   Schedule 3.20 Affiliate Transactions   Schedule 3.21(a)      Material Suppliers and Material Customers   Schedule 3.21(b)      Relationships with Material Suppliers and Material Customers   Schedule 3.24(c)      Import and Export Compliance   Schedule 4.3(a)      No Conflicts   Schedule 4.3(b)      Consents of any Governmental Authority         Exhibit A     General Release   Exhibit B Ventech Assignment and Assumption Agreement   Exhibit C Transition Services Agreement   Exhibit D Company Release   Exhibit E Calumet Release   Exhibit F Seller Release   Exhibit G Indemnification Agreement   Exhibit H Financial Statements   Exhibit I Escrow Agreement + Certain schedules and exhibits have been omitted from Exhibit 2.2 pursuant to Item 601(b)(2) of Regulation S-K. The Company hereby undertakes to furnish copies of the omitted schedules and exhibits upon request by the Securities and Exchange Commission; provided, however, that the Company may request confidential treatment pursuant to Rule 24b-2 of the Exchange Act for any schedules or exhibits so furnished.   Omitted Schedules and Exhibits   Exhibit A Letter of Resignation   Exhibit B Form of Mutual Tesoro Release   Exhibit C Form of Mutual Calumet Release 5