UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant To Section 13 OR 15(d)

of The Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): November 28, 2016

NiSource Inc.

(Exact name of registrant as specified in its charter)

Commission file number 001-16189

Registrant’s telephone number, including area code (877) 647-5990

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.

On November 28, 2016, NiSource Finance Corp. (“NiSource Finance”), as borrower, and NiSource Inc. (the “Company”), as guarantor, entered into a Fourth Amended and Restated Revolving Credit Agreement (the “Agreement”) with the lenders party thereto, Barclays Bank PLC, as Administrative Agent, JPMorgan Chase Bank, N.A. and The Bank of Tokyo-Mitsubishi UFJ, Ltd., as Co-Syndication Agents, Citibank, N.A., Credit Suisse AG, Cayman Islands Branch and Wells Fargo Bank, National Association, as Co-Documentation Agents, and Barclays Bank PLC, JPMorgan Chase Bank, N.A., The Bank of Tokyo-Mitsubishi UFJ, Ltd., Credit Suisse Securities (USA) LLC, Citigroup Global Markets, Inc. and Wells Fargo Securities, LLC, as Joint Lead Arrangers and Joint Bookrunners. The Agreement amends NiSource Finance’s existing $1.5 billion Revolving Credit Agreement to increase the facility by $350 million to $1.85 billion and to extend the term from July 1, 2020 until November 28, 2021. Up to $150 million of the facility will be available in the form of standby letters of credit. NiSource Finance has the right to increase the facility by up to an additional $500 million, subject to certain conditions and the consent of the increasing lenders. The Agreement provides that revolving loans will bear interest at the option of the Company at:

Other than increasing the size of the facility and extending the term, the Agreement substantially restates the existing Third Amended and Restated Revolving Credit Agreement, including representations and warranties, financial and other covenants and events of default.

A copy of the Agreement is filed as Exhibit 10.1 to this Current Report on Form 8-K and is incorporated herein by reference. The foregoing discussion of the Agreement in this report is a summary and is qualified in its entirety by the terms of the Agreement.

The information set forth under Item 1.01 of this Current Report on Form 8-K is incorporated by reference herein.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.