NiSource(NI) - 2025 Q3 - Quarterly Results

Exhibit 99.1 FOR IMMEDIATE RELEASE October 29, 2025 FOR ADDITIONAL INFORMATION Media Investors media@nisource.com investors@nisource.com NiSource announces third quarter results • Reaffirming upper half of 2025 non-GAAP adjusted EPS guidance • Introducing 2026 non-GAAP consolidated adjusted EPS guidance • Extending base plan expected non-GAAP adjusted EPS annual growth guidance of 6%-8% to 2026- 2030 • Introducing 2026-2033 consolidated non-GAAP adjusted EPS compound annual growth rate of 8%-9% • Announcing ...