LNT: Material agreement · New financial obligation

Item 1.01 Entry into a Material Definitive Agreement. On October 26, 2026, pursuant to the U.S. Department of Energy (the “DOE”) loan guarantee program (the “DOE Loan Guarantee Program”) established under Title XVII of the Energy Policy Act of 2005, as amended (“Title XVII”), Wisconsin Power and Light Company (“WPL”), a wholly owned subsidiary of Alliant Energy Corporation (the “Company”), entered into (i) a loan guarantee agreement, dated as of October 26, 2026 (the “WPL LGA”), between WPL and the DOE, as guarantor and loan servicer, (ii) a note purchase agreement, dated as of October 26, 2026 (the “WPL NPA”), among WPL, the Federal Financing Bank (the “FFB”) and the U.S. Secretary of Energy, acting through the DOE, and (iii) a future advance promissory note, dated October 26, 2026, made by WPL in favor of the FFB (the “WPL FFB Note” and, together with the WPL NPA, the “WPL FFB Credit Facility Documents”). The WPL LGA and the WPL FFB Credit Facility Documents are referred to herein together as the “WPL Loan Documents.” In addition, on October 26, 2026, pursuant to the DOE Loan Guarantee Program, Interstate Power and Light Company (“IPL”), a wholly owned subsidiary of the Company, entered into (i) a loan guarantee agreement, dated as of October 26, 2026 (the “IPL LGA” and, together with the WPL LGA, the “Loan Guarantee Agreements”), between IPL and the DOE, as guarantor and loan servicer, (ii) a note purchase agreement, dated as of October 26, 2026 (the “IPL NPA”), among IPL, the FFB and the U.S. Secretary of Energy, acting through the DOE, and (iii) a future advance promissory note, dated October 26, 2026, made by IPL in favor of the FFB (the “IPL FFB Note” and, together with the IPL NPA, the “IPL FFB Credit Facility Documents”). The IPL LGA and the IPL FFB Credit Faci