ALLIANT ENERGY CORP

NOTE 14. DERIVATIVE INSTRUMENTS

Commodity Derivatives -

Purpose -Derivative instruments were utilized for risk management purposes to mitigate pricing volatility for fuel used to supply natural gas-fired EGUs, natural gas supplied to retail customers, and purchased electricity, as well as optimize the value of natural gas pipeline capacity and electric generation, which may include swap, physical forward and option contracts. In addition, FTRs help manage transmission congestion costs in the MISO market. Risk policies are maintained that govern the use of such derivative instruments.

Notional Amounts -As of December 31, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts and FTRs that were accounted for as commodity derivative instruments were as follows (units in thousands):

Financial Statement Presentation - Derivative instruments are recorded at fair value each reporting date on the balance sheet as assets or liabilities. At December 31, based on the maturities of the underlying contracts, the fair values of current derivative assets are included in “Other current assets,” non-current derivative assets are included in “Deferred charges and other,” current derivative liabilities are included in “Other current liabilities” and non-current derivative liabilities are included in “Other liabilities” on the balance sheets as follows (in millions):

Based on IPL’s and WPL’s cost recovery mechanisms, the changes in the fair value of derivative liabilities/assets resulted in comparable changes to regulatory assets/liabilities on the balance sheets.

Credit Risk-related Contingent Features -Various agreements contain credit risk-related contingent features, including requirements to maintain certain credit ratings and/or limitations on liability positions under the agreements based on credit ratings. Certain of these agreements with credit risk-related contingency features are accounted for as derivative instruments. In the event of a material change in creditworthiness or if liability positions exceed certain contractual limits, credit support may need to be provided up to the amount of exposure under the contracts, or the contracts may need to be unwound and underlying liability positions paid. At December 31, 2025 and 2024, the aggregate fair value of all derivative instruments with credit risk-related contingent features in a net liability position was not materially different than amounts that would be required to be posted as credit support to counterparties by Alliant Energy, IPL or WPL if the most restrictive credit risk-related contingent features for derivative agreements in a net liability position were triggered.

Balance Sheet Offsetting - The fair value amounts of derivative instruments subject to a master netting arrangement are not netted by counterparty on the balance sheets. However, if the fair value amounts of derivative instruments by counterparty were netted, derivative assets and derivative liabilities related to commodity contracts would have been presented on the balance sheets at December 31 as follows:

Fair value amounts recognized for the right to reclaim cash collateral (receivable) or the obligation to return cash collateral (payable) are not offset against fair value amounts recognized for derivative instruments executed with the same counterparty under the same master netting arrangement.

Interest Rate Derivative - In January 2023, AEF entered into a $300 million interest rate swap maturing in January 2026 to mitigate interest rate risk. Under the terms of the swap, AEF exchanged a variable interest rate for a fixed interest rate of 3.93% on a portion of its variable-rate term loan borrowings. In 2025, 2024 and 2023, $1 million, $4 million and $3 million, respectively, of reductions to interest expense were recorded in Alliant Energy’s income statements related to the interest rate swap.

In October 2025, AEC entered into a $300 million forward starting interest rate swap maturing in March 2028 to mitigate forecasted interest rate risk. Under the terms of the swap, AEC exchanged a variable interest rate for a fixed interest rate of 3.10% on a portion of its forecasted variable-rate term loan borrowings expected to be issued in 2026. The related interest rate derivative was valued based on quoted prices that utilize current market interest rate forecasts. As of December 31, 2025, $1 million of non-current interest rate derivative assets was recorded in “Deferred charges and other” on Alliant Energy’s balance sheet. This interest rate derivative was designated as a cash flow hedge, with changes in fair value recorded as other comprehensive income. As of December 31, 2025, accumulated other comprehensive income included $1 million of income related to the interest rate swap. In 2025, there were no increases or reductions to interest expense recorded in Alliant Energy’s income statement related to the interest rate swap.