NI

SEC.gov | Request Rate Threshold Exceeded

U.S. Securities and Exchange Commission

You’ve Exceeded the SEC’s Traffic Limit

Your request rate has exceeded the SEC’s maximum allowable requests per second. Your access to SEC.gov will be limited for 10 minutes.

Current guidelines limit each user to a total of no more than 10 requests per second, regardless of the number of machines used to submit requests. To ensure that SEC.gov remains available to all users, we reserve the right to block IP addresses that submit excessive requests.

The block will be lifted automatically by waiting 10 minutes. Continuing to exceed the SEC’s maximum allowable request rate during the time-out period will extend the duration of the time-out period. To ensure fair access for all users, please reduce the rate of your requests and visit SEC.gov again after the 10 minute time-out period has passed.

For best practices on efficiently downloading information from SEC.gov, including the latest EDGAR filings, visit sec.gov/developer. You can also sign up for email updates on the SEC open data program, including best practices that make it more efficient to download data, and SEC.gov enhancements that may impact scripted downloading processes. For more information, contact opendata@sec.gov.

For more information, please see the SEC’s Web Site Privacy and Security Policy. Thank you for your interest in the U.S. Securities and Exchange Commission.

Reference ID: 0.e618d017.1786280939.b9d49d1d

More Information

Internet Security Policy

By using this site, you are agreeing to security monitoring and auditing. For security purposes, and to ensure that the public service remains available to users, this government computer system employs programs to monitor network traffic to identify unauthorized attempts to upload or change information or to otherwise cause damage, including attempts to deny service to users.

Unauthorized attempts to upload information and/or change information on any portion of this site are strictly prohibited and are subject to prosecution under the Computer Fraud and Abuse Act of 1986 and the National Information Infrastructure Protection Act of 1996 (see Title 18 U.S.C. §§ 1001 and 1030).

To ensure our website performs well for all users, the SEC monitors the frequency of requests for SEC.gov content to ensure automated searches do not impact the ability of others to access SEC.gov content. We reserve the right to block IP addresses that submit excessive requests. Current guidelines limit users to a total of no more than 10 requests per second, regardless of the number of machines used to submit requests.

If a user or application submits more than 10 requests per second, further requests from the IP address(es) may be limited for a brief period. Once the rate of requests has dropped below the threshold for 10 minutes, the user may resume accessing content on SEC.gov. This SEC practice is designed to limit excessive automated searches on SEC.gov and is not intended or expected to impact individuals browsing the SEC.gov website.

Note that this policy may change as the SEC manages SEC.gov to ensure that the website performs efficiently and remains available to all users.

Note: We do not offer technical support for developing or debugging scripted downloading processes.

EX-99.1

2 ni-ex991_20260331.htm

EX-99.1

Document

Exhibit 99.1

FOR IMMEDIATE RELEASE

May 6, 2026

FOR ADDITIONAL INFORMATION

Media                    Investors

media@nisource.com            investors@nisource.com

NiSource announces first quarter results

•GenCo cost savings expand to approximately $1.4 billion for existing customers through Alphabet and Amazon collaboration

•Raising 2026-2033 non-GAAP consolidated adjusted EPS compound annual growth rate to 9%-10%

•Reaffirming 2026 non-GAAP consolidated adjusted EPS guidance reflecting approximately 8% year-over-year growth at the midpoint

MERRILLVILLE, Ind. - NiSource Inc. (NYSE: NI) today announced, on a GAAP basis, net income available to common shareholders for the quarter ended March 31, 2026 of $510.7 million, or $1.06 of earnings per diluted share, compared to net income available to common shareholders of $474.8 million, or $1.00 of earnings per diluted share, for the same period of 2025.

NiSource also reported first quarter 2026 non-GAAP adjusted net income available to common shareholders of $509.6 million, or $1.06 of consolidated adjusted EPS, compared to consolidated non-GAAP adjusted net income available to common shareholders of $462.3 million, or $0.98 of adjusted EPS, for the same period of 2025. Schedule 1 of this press release contains a complete reconciliation of GAAP measures to non-GAAP measures. **

NiSource is reaffirming its 2026 non‑GAAP consolidated adjusted EPS guidance of $2.02-$2.07 and raising its consolidated compound annual growth rate (CAGR) with respect to non‑GAAP consolidated adjusted EPS to 9%-10% from 2026 through 2033.

"We are off to a strong start in 2026, continuing to execute on our strategy and deliver value for our customers, communities, and shareholders," said President and CEO Lloyd Yates. "We are seeing the impact of our GenCo model through new and expanded collaboration with Alphabet and Amazon, which together are expected to deliver approximately $1.4 billion in customer value, drive economic development across Indiana, strengthen our grid and position NiSource to reliably serve the growing energy demand. None of this would be possible without the continued dedication of our employees and partners as we work together to deliver safe, reliable service."

1

**Non-GAAP Disclosure Statement

This press release includes financial results and guidance for NiSource with respect to adjusted net income available to common shareholders, base plan adjusted EPS and consolidated adjusted EPS, which are non-GAAP financial measures as defined by the SEC. Commencing in 2026, the company began to present base plan adjusted EPS and consolidated adjusted EPS. As presented, guidance with respect to base plan adjusted EPS, including annual base plan adjusted EPS growth, excludes, in addition to the items historically excluded from adjusted EPS, the impact of data center operations and development activities relating to provision of electric service to current and future data center or other large load customers. The company provides guidance regarding base plan adjusted EPS because it expects that the earnings from its data center operations and development activities will experience a different growth profile compared to the base plan adjusted EPS growth. Providing guidance with respect to base plan adjusted EPS growth, together with guidance regarding consolidated adjusted EPS growth, provides investors with the same information that management considers to evaluate the company’s ongoing business performance and provide greater transparency into the performance of different aspects of our business that are impacted by distinct trends and factors. Consolidated adjusted EPS represents base plan adjusted EPS together with adjusted EPS from our data center operations and development activities. The company includes these measures because management believes they permit investors to view the company’s performance using the same tools that management uses and to better evaluate the company’s ongoing business performance. With respect to guidance on base plan adjusted EPS and consolidated adjusted EPS, NiSource reminds investors that it does not provide a GAAP equivalent of its guidance on base plan adjusted EPS or consolidated adjusted EPS due to the impact of unpredictable factors such as fluctuations in weather, impact of asset sales and impairments and other unusual or infrequent items included in the comparable GAAP measures, which may be material. The company is not able to estimate the impact of such factors on the comparable GAAP measures and, as such, the company is not able to provide a reconciliation of its non-GAAP base plan adjusted EPS guidance or its non-GAAP consolidated adjusted EPS guidance to the comparable GAAP equivalents without unreasonable efforts.

Additional Information

Additional information for the quarter ended March 31, 2026, is available on the Investors section of www.nisource.com and i

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)