NISOURCE INC.

In accordance with SEC rules, we are using the internet as our primary means of furnishing proxy materials to stockholders. Consequently, most stockholders will not receive paper copies of our proxy materials. We will instead send these stockholders a Notice of Internet Availability of Proxy Materials with instructions for accessing the proxy materials, including our Proxy Statement and Annual Report for the year ended December 31, 2025, and voting via the internet. The Notice of Internet Availability of Proxy Materials also provides information on how stockholders may obtain paper copies of our proxy materials if they so choose. This makes the proxy distribution process more efficient and less costly and helps conserve natural resources. If you previously elected to receive our proxy materials electronically, these materials will continue to be sent via email unless you change your election.