NISOURCE INC.

8. Long-Term Debt

In May 2026, we completed the issuance and sale of $500.0 million of 4.75% senior unsecured notes maturing in 2031 and $750.0 million of 5.30% senior unsecured notes maturing in 2036. The issuances resulted in approximately $1.236 billion of total net proceeds after discount and debt issuance costs.

In August 2026, we completed the issuance and sale of$750.0 million of 6.25% fixed-to-fixed reset rate junior subordinated notes maturing in 2057, which resulted in approximately$740.1 million of net proceeds after debt issuance costs. The subordinated notes bear interest (i) from and including August 2026 to, but excluding, April 2032 at a rate of 6.25% per annum and (ii) from and including April 2032, during each five-year reset period at a rate per annum equal to the five-year U.S. treasury rate (determined as described in the prospectus supplement filed with the SEC in August 2026) as of the most recent reset interest determination date plus a spread of 1.93%, to be reset on each reset date; provided that the interest rate during any reset period will not reset below 6.25% per annum. At our option, we may redeem some or all of the subordinated notes during specified periods, and upon the occurrence of certain ratings, tax or tax credit events, all as described in the prospectus supplement. In accordance with the terms of the subordinated notes, we have the right, from time to time, to defer the payment of interest on the outstanding subordinated notes on one or more occasions for up to ten consecutive years. In the event that we were to exercise such right to defer interest on the subordinated notes, we would not be able to pay cash dividends on the common stock during the periods in which such payments were deferred.