NI

nix-20260211February 11, 20260001111711False00011117112026-02-112026-02-110001111711us-gaap:CommonStockMember2026-02-112026-02-11

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): February 11, 2026 NiSource Inc. (Exact name of registrant as specified in its charter)

DE 001-16189 35-2108964

(State or other jurisdiction of incorporation or organization) Commission file number  (I.R.S. Employer Identification No.)

801 East 86th Avenue Merrillville,

IN46410

(Address of principal executive offices)(Zip Code)

Registrant’s telephone number, including area code (614) 460-6000

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.

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2 (b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4 (c))

Securities registered pursuant to Section 12(b) of the Act:

Title of Each ClassTrading Symbol(s)Name of Each Exchange on Which Registered Common Stock, par value $0.01 per shareNINYSE

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

ITEM 2.02.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.

ITEM 9.01.FINANCIAL STATEMENTS AND EXHIBITS

(d) Exhibits

Exhibit Number  Description

99.1  Press Release, dated February 11, 2026, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)

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.

NiSource Inc. (Registrant)

Date: February 11, 2026 By: /s/ Gunnar J. Gode Gunnar J. Gode Senior Vice President, Chief Accounting and Tax Officer (Principal Accounting Officer)

nix-20251029October 29, 20250001111711False00011117112025-10-292025-10-290001111711us-gaap:CommonStockMember2025-10-292025-10-29

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): October 29, 2025 NiSource Inc. (Exact name of registrant as specified in its charter)

DE 001-16189 35-2108964

(State or other jurisdiction of incorporation or organization) Commission file number  (I.R.S. Employer Identification No.)

801 East 86th Avenue Merrillville,

IN46410

(Address of principal executive offices)(Zip Code)

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.

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2 (b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4 (c))

Securities registered pursuant to Section 12(b) of the Act:

Title of Each ClassTrading Symbol(s)Name of Each Exchange on Which Registered Common Stock, par value $0.01 per shareNINYSE

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

ITEM 2.02.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.

ITEM 9.01.FINANCIAL STATEMENTS AND EXHIBITS

(d) Exhibits

Exhibit Number  Description

99.1  Press Release, dated October 29, 2025, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)

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.

NiSource Inc. (Registrant)

Date: October 29, 2025 By: /s/ Gunnar J. Gode Gunnar J. Gode Senior Vice President, Chief Accounting and Tax Officer (Principal Accounting Officer)

nix-20250806August 6, 20250001111711False00011117112025-08-062025-08-060001111711us-gaap:CommonStockMember2025-08-062025-08-06

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): August 6, 2025 NiSource Inc. (Exact name of registrant as specified in its charter)

DE 001-16189 35-2108964

(State or other jurisdiction of incorporation or organization) Commission file number  (I.R.S. Employer Identification No.)

801 East 86th Avenue Merrillville,

IN46410

(Address of principal executive offices)(Zip Code)

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.

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2 (b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4 (c))

Securities registered pursuant to Section 12(b) of the Act:

Title of Each ClassTrading Symbol(s)Name of Each Exchange on Which Registered Common Stock, par value $0.01 per shareNINYSE

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

ITEM 2.02.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.

ITEM 9.01.FINANCIAL STATEMENTS AND EXHIBITS

(d) Exhibits

Exhibit Number  Description

99.1  Press Release, dated August 6, 2025, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)

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.

NiSource Inc. (Registrant)

Date: August 6, 2025 By: /s/ Gunnar J. Gode Gunnar J. Gode Senior Vice President, Chief Accounting and Tax Officer (Principal Accounting Officer)

nix-20250507May 7, 20250001111711False00011117112025-05-072025-05-070001111711us-gaap:CommonStockMember2025-05-072025-05-07

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): May 7, 2025 NiSource Inc. (Exact name of registrant as specified in its charter)

DE 001-16189 35-2108964

(State or other jurisdiction of incorporation or organization) Commission file number  (I.R.S. Employer Identification No.)

801 East 86th Avenue Merrillville,

IN46410

(Address of principal executive offices)(Zip Code)

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.

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2 (b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4 (c))

Securities registered pursuant to Section 12(b) of the Act:

Title of Each ClassTrading Symbol(s)Name of Each Exchange on Which Registered Common Stock, par value $0.01 per shareNINYSE

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

ITEM 2.02.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.

ITEM 9.01.FINANCIAL STATEMENTS AND EXHIBITS

(d) Exhibits

Exhibit Number  Description

99.1  Press Release, dated May 7, 2025, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)

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.

NiSource Inc. (Registrant)

Date: May 7, 2025 By: /s/ Gunnar J. Gode Gunnar J. Gode Vice President, Chief Accounting Officer (Principal Accounting Officer)

nix-20250212February 12, 20250001111711False00011117112025-02-122025-02-120001111711us-gaap:CommonStockMember2025-02-122025-02-12

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): February 12, 2025 NiSource Inc. (Exact name of registrant as specified in its charter)

DE 001-16189 35-2108964

(State or other jurisdiction of incorporation or organization) Commission file number  (I.R.S. Employer Identification No.)

801 East 86th Avenue Merrillville,

IN46410

(Address of principal executive offices)(Zip Code)

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.

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2 (b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4 (c))

Securities registered pursuant to Section 12(b) of the Act:

Title of Each ClassTrading Symbol(s)Name of Each Exchange on Which Registered Common Stock, par value $0.01 per shareNINYSE

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

ITEM 2.02.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.

ITEM 9.01.FINANCIAL STATEMENTS AND EXHIBITS

(d) Exhibits

Exhibit Number  Description

99.1  Press Release, dated February 12, 2025, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)

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.

NiSource Inc. (Registrant)

Date: February 12, 2025 By: /s/ Gunnar J. Gode Gunnar J. Gode Vice President, Chief Accounting Officer (Principal Accounting Officer)

nix-20241030October 30, 20240001111711False00011117112024-10-302024-10-300001111711us-gaap:CommonStockMember2024-10-302024-10-30

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): October 30, 2024 NiSource Inc. (Exact name of registrant as specified in its charter)

DE 001-16189 35-2108964

(State or other jurisdiction of incorporation or organization) Commission file number  (I.R.S. Employer Identification No.)

801 East 86th Avenue Merrillville,

IN46410

(Address of principal executive offices)(Zip Code)

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.

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2 (b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4 (c))

Securities registered pursuant to Section 12(b) of the Act:

Title of Each ClassTrading Symbol(s)Name of Each Exchange on Which Registered Common Stock, par value $0.01 per shareNINYSE

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

ITEM 2.02.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.

ITEM 9.01.FINANCIAL STATEMENTS AND EXHIBITS

(d) Exhibits

Exhibit Number  Description

99.1  Press Release, dated October 30, 2024, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)

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.

NiSource Inc. (Registrant)

Date: October 30, 2024 By: /s/ Gunnar J. Gode Gunnar J. Gode Vice President, Chief Accounting Officer (Principal Accounting Officer)

nix-20240807August 7, 20240001111711False00011117112024-08-072024-08-070001111711us-gaap:CommonStockMember2024-08-072024-08-07

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): August 7, 2024 NiSource Inc. (Exact name of registrant as specified in its charter)

DE 001-16189 35-2108964

(State or other jurisdiction of incorporation or organization) Commission file number  (I.R.S. Employer Identification No.)

801 East 86th Avenue Merrillville,

IN46410

(Address of principal executive offices)(Zip Code)

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.

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2 (b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4 (c))

Securities registered pursuant to Section 12(b) of the Act:

Title of Each ClassTrading Symbol(s)Name of Each Exchange on Which Registered Common Stock, par value $0.01 per shareNINYSE

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

ITEM 2.02.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.

ITEM 9.01.FINANCIAL STATEMENTS AND EXHIBITS

(d) Exhibits

Exhibit Number  Description

99.1  Press Release, dated August 7, 2024, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)

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.

NiSource Inc. (Registrant)

Date: August 7, 2024 By: /s/ Gunnar J. Gode Gunnar J. Gode Vice President, Chief Accounting Officer (Principal Accounting Officer)

nix-20240508May 8, 20240001111711False00011117112024-05-082024-05-080001111711us-gaap:CommonStockMember2024-05-082024-05-08

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): May 8, 2024 NiSource Inc. (Exact name of registrant as specified in its charter)

DE 001-16189 35-2108964

(State or other jurisdiction of incorporation or organization) Commission file number  (I.R.S. Employer Identification No.)

801 East 86th Avenue Merrillville,

IN46410

(Address of principal executive offices)(Zip Code)

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.

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2 (b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4 (c))

Securities registered pursuant to Section 12(b) of the Act:

Title of Each ClassTrading Symbol(s)Name of Each Exchange on Which Registered Common Stock, par value $0.01 per shareNINYSE

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

ITEM 2.02.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.

ITEM 9.01.FINANCIAL STATEMENTS AND EXHIBITS

(d) Exhibits

Exhibit Number  Description

99.1  Press Release, dated May 8, 2024, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)

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.

NiSource Inc. (Registrant)

Date: May 8, 2024 By: /s/ Gunnar J. Gode Gunnar J. Gode Vice President, Chief Accounting Officer (Principal Accounting Officer)

nix-20240221February 21, 20240001111711False00011117112024-02-212024-02-210001111711us-gaap:CommonStockMember2024-02-212024-02-210001111711us-gaap:PreferredStockMember2024-02-212024-02-21

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): February 21, 2024 NiSource Inc. (Exact name of registrant as specified in its charter)

DE 001-16189 35-2108964

(State or other jurisdiction of incorporation or organization) Commission file number  (I.R.S. Employer Identification No.)

801 East 86th Avenue Merrillville,

IN46410

(Address of principal executive offices)(Zip Code)

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.

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2 (b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4 (c))

Securities registered pursuant to Section 12(b) of the Act:

Title of Each ClassTrading Symbol(s)Name of Each Exchange on Which Registered Common Stock, par value $0.01 per shareNINYSE Depositary Shares, each representing a 1/1,000th ownership interest in a share of 6.50% Series B Fixed-Rate Reset Cumulative Redeemable Perpetual Preferred Stock, par value $0.01 per share, liquidation preference $25,000 per share and a 1/1,000th ownership interest in a share of Series B-1 Preferred Stock, par value $0.01 per share, liquidation preference $0.01 per share

NI PR BNYSE

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

ITEM 2.02.RESULTS OF OPERATIONS AND FINANCIAL CONDITION

On February 21, 2024, NiSource Inc. (the “Company”) reported its financial results for the year ended December 31, 2023. The Company’s press release, dated February 21, 2024, is attached as Exhibit 99.1.

ITEM 9.01.FINANCIAL STATEMENTS AND EXHIBITS

(d) Exhibits

Exhibit Number  Description

99.1  Press Release, dated February 21, 2024, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)

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.

NiSource Inc. (Registrant)

Date: February 21, 2024 By: /s/ Gunnar J. Gode Gunnar J. Gode Vice President, Chief Accounting Officer (Principal Accounting Officer)

nix-20231101November 1, 20230001111711False00011117112023-11-012023-11-010001111711us-gaap:CommonStockMember2023-11-012023-11-010001111711us-gaap:PreferredStockMember2023-11-012023-11-010001111711nix:SeriesACorporateUnitsMember2023-11-012023-11-01

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 1, 2023 NiSource Inc. (Exact name of registrant as specified in its charter)

DE 001-16189 35-2108964

(State or other jurisdiction of incorporation or organization) Commission file number  (I.R.S. Employer Identification No.)

801 East 86th Avenue Merrillville,

IN46410

(Address of principal executive offices)(Zip Code)

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.

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2 (b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4 (c))

Securities registered pursuant to Section 12(b) of the Act:

Title of Each ClassTrading Symbol(s)Name of Each Exchange on Which Registered Common Stock, par value $0.01 per shareNINYSE Depositary Shares, each representing a 1/1,000th ownership interest in a share of 6.50% Series B Fixed-Rate Reset Cumulative Redeemable Perpetual Preferred Stock, par value $0.01 per share, liquidation preference $25,000 per share and a 1/1,000th ownership interest in a share of Series B-1 Preferred Stock, par value $0.01 per share, liquidation preference $0.01 per share

NI PR BNYSE

Series A Corporate UnitsNIMCNYSE

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

ITEM 2.02.RESULTS OF OPERATIONS AND FINANCIAL CONDITION

On November 1, 2023, NiSource Inc. (the “Company”) reported its financial results for the period ended September 30, 2023. The Company’s press release, dated November 1, 2023, is attached as Exhibit 99.1.

ITEM 9.01.FINANCIAL STATEMENTS AND EXHIBITS

(d) Exhibits

Exhibit Number  Description

99.1  Press Release, dated November 1, 2023, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)

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.

NiSource Inc. (Registrant)

Date: November 1, 2023 By: /s/ Gunnar J. Gode Gunnar J. Gode Vice President, Chief Accounting Officer (Principal Accounting Officer)

nix-20230802August 2, 20230001111711False00011117112023-08-022023-08-020001111711us-gaap:CommonStockMember2023-08-022023-08-020001111711us-gaap:PreferredStockMember2023-08-022023-08-020001111711nix:SeriesACorporateUnitsMember2023-08-022023-08-02

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): August 2, 2023 NiSource Inc. (Exact name of registrant as specified in its charter)

DE 001-16189 35-2108964

(State or other jurisdiction of incorporation or organization) Commission file number  (I.R.S. Employer Identification No.)

801 East 86th Avenue Merrillville,

IN46410

(Address of principal executive offices)(Zip Code)

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.

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2 (b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4 (c))

Securities registered pursuant to Section 12(b) of the Act:

Title of Each ClassTrading Symbol(s)Name of Each Exchange on Which Registered Common Stock, par value $0.01 per shareNINYSE Depositary Shares, each representing a 1/1,000th ownership interest in a share of 6.50% Series B Fixed-Rate Reset Cumulative Redeemable Perpetual Preferred Stock, par value $0.01 per share, liquidation preference $25,000 per share and a 1/1,000th ownership interest in a share of Series B-1 Preferred Stock, par value $0.01 per share, liquidation preference $0.01 per share

NI PR BNYSE

Series A Corporate UnitsNIMCNYSE

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

ITEM 2.02.RESULTS OF OPERATIONS AND FINANCIAL CONDITION

On August 2, 2023, NiSource Inc. (the “Company”) reported its financial results for the period ended June 30, 2023. The Company’s press release, dated August 2, 2023, is attached as Exhibit 99.1.

ITEM 9.01.FINANCIAL STATEMENTS AND EXHIBITS

(d) Exhibits

Exhibit Number  Description

99.1  Press Release, dated August 2, 2023, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)

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.

NiSource Inc. (Registrant)

Date: August 2, 2023 By: /s/ Gunnar J. Gode Gunnar J. Gode Vice President, Chief Accounting Officer (Principal Accounting Officer)

nix-20230503May 3, 20230001111711False00011117112023-05-032023-05-030001111711us-gaap:CommonStockMember2023-05-032023-05-030001111711us-gaap:PreferredStockMember2023-05-032023-05-030001111711nix:SeriesACorporateUnitsMember2023-05-032023-05-03

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): May 3, 2023 NiSource Inc. (Exact name of registrant as specified in its charter)

DE 001-16189 35-2108964

(State or other jurisdiction of incorporation or organization) Commission file number  (I.R.S. Employer Identification No.)

801 East 86th Avenue Merrillville,

IN46410

(Address of principal executive offices)(Zip Code)

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.

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2 (b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4 (c))

Securities registered pursuant to Section 12(b) of the Act:

Title of Each ClassTrading Symbol(s)Name of Each Exchange on Which Registered Common Stock, par value $0.01 per shareNINYSE Depositary Shares, each representing a 1/1,000th ownership interest in a share of 6.50% Series B Fixed-Rate Reset Cumulative Redeemable Perpetual Preferred Stock, par value $0.01 per share, liquidation preference $25,000 per share and a 1/1,000th ownership interest in a share of Series B-1 Preferred Stock, par value $0.01 per share, liquidation preference $0.01 per share

NI PR BNYSE

Series A Corporate UnitsNIMCNYSE

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

ITEM 2.02.RESULTS OF OPERATIONS AND FINANCIAL CONDITION

On May 3, 2023, NiSource Inc. (the “Company”) reported its financial results for the year ended March 31, 2023. The Company’s press release, dated May 3, 2023, is attached as Exhibit 99.1.

ITEM 9.01.FINANCIAL STATEMENTS AND EXHIBITS

(d) Exhibits

Exhibit Number  Description

99.1  Press Release, dated May 3, 2023, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)

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.

NiSource Inc. (Registrant)

Date: May 3, 2023 By: /s/ Gunnar J. Gode Gunnar J. Gode Vice President, Chief Accounting Officer (Principal Accounting Officer)

nix-20230222February 22, 20230001111711False00011117112023-02-222023-02-220001111711us-gaap:CommonStockMember2023-02-222023-02-220001111711us-gaap:PreferredStockMember2023-02-222023-02-220001111711nix:SeriesACorporateUnitsMember2023-02-222023-02-22

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): February 22, 2023 NiSource Inc. (Exact name of registrant as specified in its charter)

DE 001-16189 35-2108964

(State or other jurisdiction of incorporation or organization) Commission file number  (I.R.S. Employer Identification No.)

801 East 86th Avenue Merrillville,

IN46410

(Address of principal executive offices)(Zip Code)

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.

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2 (b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4 (c))

Securities registered pursuant to Section 12(b) of the Act:

Title of Each ClassTrading Symbol(s)Name of Each Exchange on Which Registered Common Stock, par value $0.01 per shareNINYSE Depositary Shares, each representing a 1/1,000th ownership interest in a share of 6.50% Series B Fixed-Rate Reset Cumulative Redeemable Perpetual Preferred Stock, par value $0.01 per share, liquidation preference $25,000 per share and a 1/1,000th ownership interest in a share of Series B-1 Preferred Stock, par value $0.01 per share, liquidation preference $0.01 per share

NI PR BNYSE

Series A Corporate UnitsNIMCNYSE

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

ITEM 2.02.RESULTS OF OPERATIONS AND FINANCIAL CONDITION

On February 22, 2023, NiSource Inc. (the “Company”) reported its financial results for the year ended December 31, 2022. The Company’s press release, dated February 22, 2023, is attached as Exhibit 99.1.

ITEM 9.01.FINANCIAL STATEMENTS AND EXHIBITS

(d) Exhibits

Exhibit Number  Description

99.1  Press Release, dated February 22, 2023, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)

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.

NiSource Inc. (Registrant)

Date: February 22, 2023 By: /s/ Gunnar J. Gode Gunnar J. Gode Vice President, Chief Accounting Officer and Controller (Principal Accounting Officer)

nix-20221107November 7, 20220001111711False00011117112022-11-072022-11-070001111711us-gaap:CommonStockMember2022-11-072022-11-070001111711us-gaap:PreferredStockMember2022-11-072022-11-070001111711nix:SeriesACorporateUnitsMember2022-11-072022-11-07

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 7, 2022 NiSource Inc. (Exact name of registrant as specified in its charter)

DE 001-16189 35-2108964

(State or other jurisdiction of incorporation or organization) Commission file number  (I.R.S. Employer Identification No.)

801 East 86th Avenue Merrillville,

IN46410

(Address of principal executive offices)(Zip Code)

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.

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2 (b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4 (c))

Securities registered pursuant to Section 12(b) of the Act:

Title of Each ClassTrading Symbol(s)Name of Each Exchange on Which Registered Common Stock, par value $0.01 per shareNINYSE Depositary Shares, each representing a 1/1,000th ownership interest in a share of 6.50% Series B Fixed-Rate Reset Cumulative Redeemable Perpetual Preferred Stock, par value $0.01 per share, liquidation preference $25,000 per share and a 1/1,000th ownership interest in a share of Series B-1 Preferred Stock, par value $0.01 per share, liquidation preference $0.01 per share

NI PR BNYSE

Series A Corporate UnitsNIMCNYSE

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

ITEM 2.02.RESULTS OF OPERATIONS AND FINANCIAL CONDITION

On November 7, 2022, NiSource Inc. (the “Company”) reported its financial results for the year ended September 30, 2022. The Company’s press release, dated November 7, 2022, is attached as Exhibit 99.1.

ITEM 7.01.REGULATION FD DISCLOSURE

On November 7, 2022, the Company issued a press release to provide information regarding the Company’s business review, long-term growth plan and 2040 net-zero emissions goal, in connection with and in advance of the Company’s Investor Day event scheduled for noon Eastern Time at the New York Stock Exchange. A copy of the press release is furnished as an exhibit to this report.

The information furnished in this Item 7.01 (including Exhibit 99.2) shall not be deemed to be “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, and is not incorporated by reference into any filing under the Securities Act of 1933, as amended, or the Exchange Act.

ITEM 9.01.FINANCIAL STATEMENTS AND EXHIBITS

(d) Exhibits

Exhibit Number  Description

99.1  Press Release, dated November 7, 2022, issued by NiSource Inc.

99.2Press Release, dated November 7, 2022, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)

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.

NiSource Inc. (Registrant)

Date: November 7, 2022 By: /s/ Gunnar J. Gode Gunnar J. Gode Vice President, Chief Accounting Officer and Controller (Principal Accounting Officer)

EXHIBIT INDEX

Exhibit Number  Description

99.1  Press Release, dated November 7, 2022, issued by NiSource Inc.

99.2Press Release, dated November 7, 2022, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive

nix-20220803August 3, 20220001111711False00011117112022-08-032022-08-030001111711us-gaap:CommonStockMember2022-08-032022-08-030001111711us-gaap:PreferredStockMember2022-08-032022-08-030001111711nix:SeriesACorporateUnitsMember2022-08-032022-08-03

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): August 3, 2022 NiSource Inc. (Exact name of registrant as specified in its charter)

DE 001-16189 35-2108964

(State or other jurisdiction of incorporation or organization) Commission file number  (I.R.S. Employer Identification No.)

801 East 86th Avenue Merrillville,

IN46410

(Address of principal executive offices)(Zip Code)

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.

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2 (b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4 (c))

Securities registered pursuant to Section 12(b) of the Act:

Title of Each ClassTrading Symbol(s)Name of Each Exchange on Which Registered Common Stock, par value $0.01 per shareNINYSE Depositary Shares, each representing a 1/1,000th ownership interest in a share of 6.50% Series B Fixed-Rate Reset Cumulative Redeemable Perpetual Preferred Stock, par value $0.01 per share, liquidation preference $25,000 per share and a 1/1,000th ownership interest in a share of Series B-1 Preferred Stock, par value $0.01 per share, liquidation preference $0.01 per share

NI PR BNYSE

Series A Corporate UnitsNIMCNYSE

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

ITEM 2.02.RESULTS OF OPERATIONS AND FINANCIAL CONDITION

On August 3, 2022, NiSource Inc. (the “Company”) reported its financial results for the year ended June 30, 2022. The Company’s press release, dated August 3, 2022, is attached as Exhibit 99.1.

ITEM 9.01.FINANCIAL STATEMENTS AND EXHIBITS

(d) Exhibits

Exhibit Number  Description

99.1  Press Release, dated August 3, 2022, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)

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.

NiSource Inc. (Registrant)

Date: August 3, 2022 By: /s/ Gunnar J. Gode Gunnar J. Gode Vice President, Chief Accounting Officer and Controller (Principal Accounting Officer)

EXHIBIT INDEX

Exhibit Number  Description

99.1  Press Release, dated August 3, 2022, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)

nix-20220504May 4, 20220001111711False00011117112022-05-042022-05-040001111711us-gaap:CommonStockMember2022-05-042022-05-040001111711us-gaap:PreferredStockMember2022-05-042022-05-040001111711nix:SeriesACorporateUnitsMember2022-05-042022-05-04

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): May 4, 2022 NiSource Inc. (Exact name of registrant as specified in its charter)

DE 001-16189 35-2108964

(State or other jurisdiction of incorporation or organization) Commission file number  (I.R.S. Employer Identification No.)

801 East 86th Avenue Merrillville,

IN46410

(Address of principal executive offices)(Zip Code)

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.

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2 (b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4 (c))

Securities registered pursuant to Section 12(b) of the Act:

Title of Each ClassTrading Symbol(s)Name of Each Exchange on Which Registered Common Stock, par value $0.01 per shareNINYSE Depositary Shares, each representing a 1/1,000th ownership interest in a share of 6.50% Series B Fixed-Rate Reset Cumulative Redeemable Perpetual Preferred Stock, par value $0.01 per share, liquidation preference $25,000 per share and a 1/1,000th ownership interest in a share of Series B-1 Preferred Stock, par value $0.01 per share, liquidation preference $0.01 per share

NI PR BNYSE

Series A Corporate UnitsNIMCNYSE

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

ITEM 2.02.RESULTS OF OPERATIONS AND FINANCIAL CONDITION

On May 4, 2022, NiSource Inc. (the “Company”) reported its financial results for the year ended March 31, 2022. The Company’s press release, dated May 4, 2022, is attached as Exhibit 99.1.

ITEM 9.01.FINANCIAL STATEMENTS AND EXHIBITS

(d) Exhibits

Exhibit Number  Description

99.1  Press Release, dated May 4, 2022, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)

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.

NiSource Inc. (Registrant)

Date: May 4, 2022 By: /s/ Gunnar J. Gode Gunnar J. Gode Vice President, Chief Accounting Officer and Controller (Principal Accounting Officer)

EXHIBIT INDEX

Exhibit Number  Description

99.1  Press Release, dated May 4, 2022, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)

nix-20220223February 23, 20220001111711False00011117112022-02-232022-02-230001111711us-gaap:CommonStockMember2022-02-232022-02-230001111711us-gaap:PreferredStockMember2022-02-232022-02-230001111711nix:SeriesACorporateUnitsMember2022-02-232022-02-23

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): February 23, 2022 NiSource Inc. (Exact name of registrant as specified in its charter)

DE 001-16189 35-2108964

(State or other jurisdiction of incorporation or organization) Commission file number  (I.R.S. Employer Identification No.)

801 East 86th Avenue Merrillville,

IN46410

(Address of principal executive offices)(Zip Code)

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.

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2 (b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4 (c))

Securities registered pursuant to Section 12(b) of the Act:

Title of Each ClassTrading Symbol(s)Name of Each Exchange on Which Registered Common Stock, par value $0.01 per shareNINYSE Depositary Shares, each representing a 1/1,000th ownership interest in a share of 6.50% Series B Fixed-Rate Reset Cumulative Redeemable Perpetual Preferred Stock, par value $0.01 per share, liquidation preference $25,000 per share and a 1/1,000th ownership interest in a share of Series B-1 Preferred Stock, par value $0.01 per share, liquidation preference $0.01 per share

NI PR BNYSE

Series A Corporate UnitsNIMCNYSE

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

ITEM 2.02.RESULTS OF OPERATIONS AND FINANCIAL CONDITION

On February 23, 2022, NiSource Inc. (the “Company”) reported its financial results for the year ended December 31, 2021. The Company’s press release, dated February 23, 2022, is attached as Exhibit 99.1.

ITEM 9.01.FINANCIAL STATEMENTS AND EXHIBITS

(d) Exhibits

Exhibit Number  Description

99.1  Press Release, dated February 23, 2022, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)

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.

NiSource Inc. (Registrant)

Date: February 23, 2022 By: /s/ Gunnar J. Gode Gunnar J. Gode Vice President, Chief Accounting Officer and Controller (Principal Accounting Officer)

EXHIBIT INDEX

Exhibit Number  Description

99.1  Press Release, dated February 23, 2022, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)

nix-20211103November 3, 20210001111711FalseDepositary Shares, each representing a 1/1,000th ownership interest in a share of 6.50% Series B Fixed-Rate Reset Cumulative Redeemable Perpetual00011117112021-11-032021-11-030001111711us-gaap:CommonStockMember2021-11-032021-11-030001111711us-gaap:PreferredStockMember2021-11-032021-11-030001111711nix:SeriesACorporateUnitsMember2021-11-032021-11-03

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 3, 2021 NiSource Inc. (Exact name of registrant as specified in its charter)

DE 001-16189 35-2108964

(State or other jurisdiction of incorporation or organization) Commission file number  (I.R.S. Employer Identification No.)

801 East 86th Avenue Merrillville,

IN46410

(Address of principal executive offices)(Zip Code)

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.

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2 (b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4 (c))

Securities registered pursuant to Section 12(b) of the Act:

Title of Each ClassTrading Symbol(s)Name of Each Exchange on Which Registered Common Stock, par value $0.01 per shareNINYSE Depositary Shares, each representing a 1/1,000th ownership interest in a share of 6.50% Series B Fixed-Rate Reset Cumulative Redeemable Perpetual Preferred Stock, par value $0.01 per share, liquidation preference $25,000 per share and a 1/1,000th ownership interest in a share of Series B-1 Preferred Stock, par value $0.01 per share, liquidation preference $0.01 per share

NI PR BNYSE

Series A Corporate UnitsNIMCNYSE

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

ITEM 2.02.RESULTS OF OPERATIONS AND FINANCIAL CONDITION

On November 3, 2021, NiSource Inc. (the “Company”) reported its financial results for the year ended September 30, 2021. The Company’s press release, dated November 3, 2021, is attached as Exhibit 99.1.

ITEM 9.01.FINANCIAL STATEMENTS AND EXHIBITS

(d) Exhibits

Exhibit Number  Description

99.1  Press Release, dated November 3, 2021, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)

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.

NiSource Inc. (Registrant)

Date: November 3, 2021 By: /s/ Gunnar J. Gode Gunnar J. Gode Vice President, Chief Accounting Officer and Controller (Principal Accounting Officer)

EXHIBIT INDEX

Exhibit Number  Description

99.1  Press Release, dated November 3, 2021, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)

nix-20210804August 4, 20210001111711False00011117112021-08-042021-08-040001111711us-gaap:CommonStockMember2021-08-042021-08-040001111711us-gaap:PreferredStockMember2021-08-042021-08-040001111711nix:SeriesACorporateUnitsMember2021-08-042021-08-04

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): August 4, 2021 NiSource Inc. (Exact name of registrant as specified in its charter)

DE 001-16189 35-2108964

(State or other jurisdiction of incorporation or organization) Commission file number  (I.R.S. Employer Identification No.)

801 East 86th Avenue Merrillville,

IN46410

(Address of principal executive offices)(Zip Code)

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.

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2 (b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4 (c))

Securities registered pursuant to Section 12(b) of the Act:

Title of Each ClassTrading Symbol(s)Name of Each Exchange on Which Registered Common Stock, par value $0.01 per shareNINYSE Depositary Shares, each representing a 1/1,000th ownership interest in a share of 6.50% Series BNI PR BNYSE Fixed-Rate Reset Cumulative Redeemable Perpetual Preferred Stock, par value $0.01 per share, liquidation preference $25,000 per share and a 1/1,000th ownership interest in a share of Series B-1 Preferred Stock, par value $0.01 per share, liquidation preference $0.01 per share Series A Corporate UnitsNIMCNYSE

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

ITEM 2.02.RESULTS OF OPERATIONS AND FINANCIAL CONDITION

On August 4, 2021, NiSource Inc. (the “Company”) reported its financial results for the year ended June 30, 2021. The Company’s press release, dated August 4, 2021, is attached as Exhibit 99.1.

ITEM 9.01.FINANCIAL STATEMENTS AND EXHIBITS

(d) Exhibits

Exhibit Number  Description

99.1  Press Release, dated August 4, 2021, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)

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.

NiSource Inc. (Registrant)

Date: August 4, 2021 By: /s/ Gunnar J. Gode Gunnar J. Gode Vice President, Chief Accounting Officer and Controller (Principal Accounting Officer)

EXHIBIT INDEX

Exhibit Number  Description

99.1  Press Release, dated August 4, 2021, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)

nix-20210505May 5, 20210001111711False00011117112021-05-052021-05-050001111711us-gaap:CommonStockMember2021-05-052021-05-050001111711us-gaap:PreferredStockMember2021-05-052021-05-050001111711nix:SeriesACorporateUnitsMember2021-05-052021-05-05

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): May 5, 2021 NiSource Inc. (Exact name of registrant as specified in its charter)

DE 001-16189 35-2108964

(State or other jurisdiction of incorporation or organization) Commission file number  (I.R.S. Employer Identification No.)

801 East 86th Avenue Merrillville,

IN46410

(Address of principal executive offices)(Zip Code)

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.

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2 (b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4 (c))

Securities registered pursuant to Section 12(b) of the Act:

Title of Each ClassTrading Symbol(s)Name of Each Exchange on Which Registered Common Stock, par value $0.01 per shareNINYSE Depositary Shares, each representing a 1/1,000th ownership interest in a share of 6.50% Series BNI PR BNYSE Fixed-Rate Reset Cumulative Redeemable Perpetual Preferred Stock, par value $0.01 per share, liquidation preference $25,000 per share and a 1/1,000th ownership interest in a share of Series B-1 Preferred Stock, par value $0.01 per share, liquidation preference $0.01 per share Series A Corporate UnitsNIMCNYSE

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

ITEM 2.02.RESULTS OF OPERATIONS AND FINANCIAL CONDITION

On May 5, 2021, NiSource Inc. (the “Company”) reported its financial results for the year ended March 31, 2021. The Company’s press release, dated May 5, 2021, is attached as Exhibit 99.1.

ITEM 9.01.FINANCIAL STATEMENTS AND EXHIBITS

(d) Exhibits

Exhibit Number  Description

99.1  Press Release, dated May 5, 2021, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)

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.

NiSource Inc. (Registrant)

Date: May 5, 2021 By: /s/ Gunnar J. Gode Gunnar J. Gode Vice President, Chief Accounting Officer and Controller (Principal Accounting Officer)

EXHIBIT INDEX

Exhibit Number  Description

99.1  Press Release, dated May 5, 2021, issued by NiSource Inc.

101.INSInline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.

101.SCHInline XBRL Schema Document

101.CALInline XBRL Calculation Linkbase Document

101.LABInline XBRL Labels Linkbase Document

101.PREInline XBRL Presentation Linkbase Document

101.DEFInline XBRL Definition Linkbase Document

104Cover page Interactive Data File (formatted as inline XBRL, and contained in Exhibit 101.)