# EDGAR Filing Document

**Accession Number:** 0001111711
**File Stem:** 0001140361-26-011852
**Filing Date:** 2026-3
**Character Count:** 2258
**Document Hash:** 75433cf047304741f3e2c2bb7bb7dd30
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001140361-26-011852.hdr.sgml**: 20260330

**ACCESSION NUMBER**: 0001140361-26-011852

**CONFORMED SUBMISSION TYPE**: DEFA14A

**PUBLIC DOCUMENT COUNT**: 3

**FILED AS OF DATE**: 20260330

**DATE AS OF CHANGE**: 20260330

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** NISOURCE INC.
- **CENTRAL INDEX KEY:** 0001111711
- **STANDARD INDUSTRIAL CLASSIFICATION:** ELECTRIC & OTHER SERVICES COMBINED [4931]
- **ORGANIZATION NAME:** 01 Energy & Transportation
- **EIN:** 352108964
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** DEFA14A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-16189
- **FILM NUMBER:** 26809872

**BUSINESS ADDRESS:**
- **STREET 1:** 801 EAST 86TH AVE
- **CITY:** MERRILLVILLE
- **STATE:** IN
- **ZIP:** 46410-6272
- **BUSINESS PHONE:** 2196475200

**MAIL ADDRESS:**
- **STREET 1:** 801 EAST 86TH AVE
- **CITY:** MERRILLVILLE
- **STATE:** IN
- **ZIP:** 46410-6272

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** NISOURCE INC/DE
- **DATE OF NAME CHANGE:** 20001103

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** NEW NISOURCE INC
- **DATE OF NAME CHANGE:** 20000412

#### UNITED STATES

### SECURITIES AND EXCHANGE COMMISSION

#### Washington, D.C. 20549

#### <br>

### SCHEDULE 14A INFORMATION

#### <br>

#### Proxy Statement Pursuant to Section 14(a) of the

#### Securities Exchange Act of 1934

#### (Amendment No.)

#### <br>
Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐

Check the appropriate box:

☐ Preliminary Proxy Statement

☐ **Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))**

☐ Definitive Proxy Statement

☒ Definitive Additional Materials

☐ Soliciting Material under Rule 14a-12

## NISOURCE INC.

#### (Name of Registrant as Specified In Its Charter)

#### <br>

#### (Name of Person(s) Filing Proxy Statement, if other than the registrant)

#### <br>
Payment of Filing Fee (Check the appropriate box):

☒ No fee required. <br> ☐ Fee paid previously with preliminary materials. <br> ☐ Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(4) and 0-11.

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