Other Events. 6.250% Fixed-to-Fixed Reset Rate Junior Subordinated Notes due 2057 On August 13, 2026, NiSource Inc. (the “Company”) and Barclays Capital Inc., Goldman Sachs & Co. LLC, J.P. Morgan Securities LLC, Morgan Stanley & Co. LLC and Wells Fargo Securities, LLC, as lead underwriters, entered into a Terms Agreement (the “Terms Agreement”) with respect to the offering and sale of $750,000,000 aggregate principal amount of the Company’s 6.250% Fixed-to-Fixed Reset Rate Junior Subordinated…

RESULTS OF OPERATIONS AND FINANCIAL CONDITION On August 5, 2026, NiSource Inc. (the “Company”) reported its financial results for the period ended June 30, 2026. The Company’s press release, dated August 5, 2026, is attached as Exhibit 99.1.

Other Events. Senior Notes Due 2031 and 2036 On May 11, 2026, NiSource Inc. (the “Company”) and BNP Paribas Securities Corp., BofA Securities, Inc., MUFG Securities Americas Inc. and U.S. Bancorp Investments, Inc., as Lead Underwriters, entered into a Terms Agreement (the “Terms Agreement”) with respect to the offering and sale of $500,000,000 aggregate principal amount of the Company’s 4.750% Notes due 2031 (the “2031 Notes”) and $750,000,000 aggregate principal amount of the Company’s 5.300…

RESULTS OF OPERATIONS AND FINANCIAL CONDITION On May 6, 2026, NiSource Inc. (the “Company”) reported its financial results for the period ended March 31, 2026. The Company’s press release, dated May 6, 2026, is attached as Exhibit 99.1.

RESULTS OF OPERATIONS AND FINANCIAL CONDITION On February 11, 2026, NiSource Inc. (the “Company”) reported its financial results for the year ended December 31, 2025. The Company’s press release, dated February 11, 2026, is attached as Exhibit 99.1.

Entry into a Material Definitive Agreement. On December 11, 2025, NiSource Inc. (“NiSource”), as Borrower, entered into a Seventh Amended and Restated Revolving Credit Agreement (the “Agreement”) with the lenders party thereto, Barclays Bank PLC, as Administrative Agent, JPMorgan Chase Bank, N.A., MUFG Bank, Ltd. and Wells Fargo Bank, National Association, as Co-Syndication Agents, Bank of America, National Association, Bank of Montreal and Mizuho Bank, Ltd., as Co-Documentation Agents, and B…

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant. The information set forth under

Other Events. 5.750% Fixed-to-Fixed Reset Rate Junior Subordinated Notes due 2056 On November 3, 2025, NiSource Inc. (the “Company”) and Barclays Capital Inc., Goldman Sachs & Co. LLC, Mizuho Securities USA LLC, Morgan Stanley & Co. LLC and MUFG Securities Americas Inc., as lead underwriters, entered into a Terms Agreement (the “Terms Agreement”) with respect to the offering and sale of $1,000,000,000 aggregate principal amount of the Company’s 5.750% Fixed-to-Fixed Reset Rate Junior Subordin…

Entry into a Material Definitive Agreement On October 31, 2025, NiSource Inc. (the “ Company ”) entered into eleven separate equity distribution agreements, each dated October 31, 2025 (the “ Equity Distribution Agreements ”), (i) among the Company, Barclays Capital Inc., as sales agent and as forward seller, and Barclays Bank PLC, as forward purchaser, (ii) among the Company, BMO Capital Markets Corp., as sales agent and forward seller, and Bank of Montreal, as forward purchaser, (iii) among…

RESULTS OF OPERATIONS AND FINANCIAL CONDITION On October 29, 2025, NiSource Inc. (the “Company”) reported its financial results for the period ended September 30, 2025. The Company’s press release, dated October 29, 2025, is attached as Exhibit 99.1.

of Form 8-K and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference into any of the Company’s filings under the Securities Act of 1933 or the Securities Exchange Act of 1934, whether made before or after the date hereof and regardless of any general incorporation language in such filings, except to the extent expressly set forth by specific refer…

RESULTS OF OPERATIONS AND FINANCIAL CONDITION On August 6, 2025, NiSource Inc. (the “Company”) reported its financial results for the period ended June 30, 2025. The Company’s press release, dated August 6, 2025, is attached as Exhibit 99.1.

Other Events. Senior Notes Due 2035 and 2055 On June 23, 2025, NiSource Inc. (the “Company”) and BMO Capital Markets Corp., BNP Paribas Securities Corp., J.P. Morgan Securities LLC, PNC Capital Markets LLC, Scotia Capital (USA) Inc. and U.S. Bancorp Investments, Inc., as Lead Underwriters, entered into a Terms Agreement (the “Terms Agreement”) with respect to the offering and sale of $900,000,000 aggregate principal amount of the Company’s 5.350% Notes due 2035 (the “2035 Notes”) and $750,000…

RESULTS OF OPERATIONS AND FINANCIAL CONDITION On May 7, 2025, NiSource Inc. (the “Company”) reported its financial results for the period ended March 31, 2025. The Company’s press release, dated May 7, 2025, is attached as Exhibit 99.1.

Other Events. Senior Notes Due 2055 On March 20, 2025, NiSource Inc. (the “Company”) and Barclays Capital Inc., BofA Securities, Inc., KeyBanc Capital Markets Inc. and Wells Fargo Securities, LLC, as representatives of the underwriters, entered into a Terms Agreement (the “Terms Agreement”) with respect to the offering and sale of $750,000,000 aggregate principal amount of the Company’s 5.850% Notes due 2055 (the “Notes”) under the Company’s Registration Statement on Form S-3 (File No. 333-26…

RESULTS OF OPERATIONS AND FINANCIAL CONDITION On February 12, 2025, NiSource Inc. (the “Company”) reported its financial results for the year ended December 31, 2024. The Company’s press release, dated February 12, 2025, is attached as Exhibit 99.1.

Executive Vice President — Michael Luhrs: The filing discloses a one-time equity compensation award to a senior executive, not a change in management status or departure.

RESULTS OF OPERATIONS AND FINANCIAL CONDITION On October 30, 2024, NiSource Inc. (the “Company”) reported its financial results for the period ended September 30, 2024. The Company’s press release, dated October 30, 2024, is attached as Exhibit 99.1.

Material Modification to Rights of Security Holders. The information set forth under

Other Events. 6.375% Fixed-to-Fixed Reset Rate Junior Subordinated Notes due 2055 On September 3, 2024, NiSource Inc. (the “Company”) and BofA Securities, Inc., Goldman Sachs & Co. LLC, J.P. Morgan Securities LLC, Morgan Stanley & Co, LLC and Wells Fargo Securities, LLC, as underwriters, entered into a Terms Agreement (the “Terms Agreement”) with respect to the offering and sale of $500,000,000 aggregate principal amount of the Company’s 6.375% Fixed-to-Fixed Reset Rate Junior Subordinated No…

RESULTS OF OPERATIONS AND FINANCIAL CONDITION On August 7, 2024, NiSource Inc. (the “Company”) reported its financial results for the period ended June 30, 2024. The Company’s press release, dated August 7, 2024, is attached as Exhibit 99.1.

Other Events. Senior Notes Due 2029 On June 17, 2024, NiSource Inc. (the “Company”) and Barclays Capital Inc., BNP Paribas Securities Corp., KeyBanc Capital Markets Inc., MUFG Securities Americas Inc. and Scotia Capital (USA) Inc., as representatives of the underwriters, entered into a Terms Agreement (the “Terms Agreement”) with respect to the offering and sale of $600,000,000 aggregate principal amount of the Company’s 5.200% Notes due 2029 (the “Notes”) under the Company’s Registration Sta…

Other Events. 6.950% Fixed-to-Fixed Reset Rate Junior Subordinated Notes due 2054 On May 13, 2024, NiSource Inc. (the “Company”) and BofA Securities, Inc., Goldman Sachs & Co. LLC, J.P. Morgan Securities LLC, Morgan Stanley & Co. LLC and Wells Fargo Securities, LLC, as representatives of the underwriters, entered into a Terms Agreement (the “Terms Agreement”) with respect to the offering and sale of $500,000,000 aggregate principal amount of the Company’s 6.950% Fixed-to-Fixed Reset Rate Juni…

RESULTS OF OPERATIONS AND FINANCIAL CONDITION On May 8, 2024, NiSource Inc. (the “Company”) reported its financial results for the period ended March 31, 2024. The Company’s press release, dated May 8, 2024, is attached as Exhibit 99.1.

Director — Aristides S. Candris: A board member retired and was immediately replaced by a qualified successor, representing an orderly succession rather than a loss of senior executive management.