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Derivative Instruments | 9 Months Ended
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Sep. 30, 2025
Derivative Instruments [Line Items] |
Derivative Instruments | DERIVATIVE INSTRUMENTS Commodity Derivatives - Notional Amounts - As of September 30, 2025, 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):
| Electricity |  | FTRs |  | Natural Gas |  |  |  | Diesel Fuel
| MWhs |  | Years |  | MWhs |  | Years |  | Dths |  | Years |  |  |  |  |  | Gallons |  | Years
Alliant Energy | 1,689 |  |  | 2025-2026 |  | 17,992 |  |  | 2025-2026 |  | 136,910 |  |  | 2025-2032 |  |  |  |  |  | 630 |  |  | 2025
IPL | 563 |  |  | 2025-2026 |  | 7,143 |  |  | 2025-2026 |  | 56,355 |  |  | 2025-2030 |  |  |  |  |  | — |  |  | —
WPL | 1,126 |  |  | 2025-2026 |  | 10,849 |  |  | 2025-2026 |  | 80,555 |  |  | 2025-2032 |  |  |  |  |  | 630 |  |  | 2025
Financial Statement Presentation - Derivative instruments are recorded at fair value each reporting date on the balance sheets as assets or liabilities as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| September 30, 2025 |  | December 31, 2024 |  | September 30, 2025 |  | December 31, 2024 |  | September 30, 2025 |  | December 31, 2024
Current derivative assets | $55 |  | $41 |  | $38 |  | $29 |  | $17 |  | $12
Non-current derivative assets | 27 |  | 34 |  | 14 |  | 19 |  | 13 |  | 15
Current derivative liabilities | 22 |  | 26 |  | 8 |  | 11 |  | 14 |  | 15
Non-current derivative liabilities | 26 |  | 32 |  | 2 |  | 2 |  | 24 |  | 30
Based on IPL’s and WPL’s cost recovery mechanisms, the changes in the fair value of derivative liabilities/assets result 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 September 30, 2025 and December 31, 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 as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| Gross |  |  |  | Gross |  |  |  | Gross |  |
| (as reported) |  | Net |  | (as reported) |  | Net |  | (as reported) |  | Net
September 30, 2025 |  |  |  |  |  |  |  |  |  |  |
Derivative assets | $82 |  | $72 |  | $52 |  | $47 |  | $30 |  | $25
Derivative liabilities | 48 |  | 38 |  | 10 |  | 5 |  | 38 |  | 33
December 31, 2024 |  |  |  |  |  |  |  |  |  |  |
Derivative assets | 75 |  | 64 |  | 48 |  | 43 |  | 27 |  | 21
Derivative liabilities | 58 |  | 47 |  | 13 |  | 8 |  | 45 |  | 39
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.
IPL [Member] |
Derivative Instruments [Line Items] |
Derivative Instruments | DERIVATIVE INSTRUMENTS Commodity Derivatives - Notional Amounts - As of September 30, 2025, 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):
| Electricity |  | FTRs |  | Natural Gas |  |  |  | Diesel Fuel
| MWhs |  | Years |  | MWhs |  | Years |  | Dths |  | Years |  |  |  |  |  | Gallons |  | Years
Alliant Energy | 1,689 |  |  | 2025-2026 |  | 17,992 |  |  | 2025-2026 |  | 136,910 |  |  | 2025-2032 |  |  |  |  |  | 630 |  |  | 2025
IPL | 563 |  |  | 2025-2026 |  | 7,143 |  |  | 2025-2026 |  | 56,355 |  |  | 2025-2030 |  |  |  |  |  | — |  |  | —
WPL | 1,126 |  |  | 2025-2026 |  | 10,849 |  |  | 2025-2026 |  | 80,555 |  |  | 2025-2032 |  |  |  |  |  | 630 |  |  | 2025
Financial Statement Presentation - Derivative instruments are recorded at fair value each reporting date on the balance sheets as assets or liabilities as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| September 30, 2025 |  | December 31, 2024 |  | September 30, 2025 |  | December 31, 2024 |  | September 30, 2025 |  | December 31, 2024
Current derivative assets | $55 |  | $41 |  | $38 |  | $29 |  | $17 |  | $12
Non-current derivative assets | 27 |  | 34 |  | 14 |  | 19 |  | 13 |  | 15
Current derivative liabilities | 22 |  | 26 |  | 8 |  | 11 |  | 14 |  | 15
Non-current derivative liabilities | 26 |  | 32 |  | 2 |  | 2 |  | 24 |  | 30
Based on IPL’s and WPL’s cost recovery mechanisms, the changes in the fair value of derivative liabilities/assets result 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 September 30, 2025 and December 31, 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 as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| Gross |  |  |  | Gross |  |  |  | Gross |  |
| (as reported) |  | Net |  | (as reported) |  | Net |  | (as reported) |  | Net
September 30, 2025 |  |  |  |  |  |  |  |  |  |  |
Derivative assets | $82 |  | $72 |  | $52 |  | $47 |  | $30 |  | $25
Derivative liabilities | 48 |  | 38 |  | 10 |  | 5 |  | 38 |  | 33
December 31, 2024 |  |  |  |  |  |  |  |  |  |  |
Derivative assets | 75 |  | 64 |  | 48 |  | 43 |  | 27 |  | 21
Derivative liabilities | 58 |  | 47 |  | 13 |  | 8 |  | 45 |  | 39
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.
WPL [Member] |
Derivative Instruments [Line Items] |
Derivative Instruments | DERIVATIVE INSTRUMENTS Commodity Derivatives - Notional Amounts - As of September 30, 2025, 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):
| Electricity |  | FTRs |  | Natural Gas |  |  |  | Diesel Fuel
| MWhs |  | Years |  | MWhs |  | Years |  | Dths |  | Years |  |  |  |  |  | Gallons |  | Years
Alliant Energy | 1,689 |  |  | 2025-2026 |  | 17,992 |  |  | 2025-2026 |  | 136,910 |  |  | 2025-2032 |  |  |  |  |  | 630 |  |  | 2025
IPL | 563 |  |  | 2025-2026 |  | 7,143 |  |  | 2025-2026 |  | 56,355 |  |  | 2025-2030 |  |  |  |  |  | — |  |  | —
WPL | 1,126 |  |  | 2025-2026 |  | 10,849 |  |  | 2025-2026 |  | 80,555 |  |  | 2025-2032 |  |  |  |  |  | 630 |  |  | 2025
Financial Statement Presentation - Derivative instruments are recorded at fair value each reporting date on the balance sheets as assets or liabilities as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| September 30, 2025 |  | December 31, 2024 |  | September 30, 2025 |  | December 31, 2024 |  | September 30, 2025 |  | December 31, 2024
Current derivative assets | $55 |  | $41 |  | $38 |  | $29 |  | $17 |  | $12
Non-current derivative assets | 27 |  | 34 |  | 14 |  | 19 |  | 13 |  | 15
Current derivative liabilities | 22 |  | 26 |  | 8 |  | 11 |  | 14 |  | 15
Non-current derivative liabilities | 26 |  | 32 |  | 2 |  | 2 |  | 24 |  | 30
Based on IPL’s and WPL’s cost recovery mechanisms, the changes in the fair value of derivative liabilities/assets result 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 September 30, 2025 and December 31, 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 as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| Gross |  |  |  | Gross |  |  |  | Gross |  |
| (as reported) |  | Net |  | (as reported) |  | Net |  | (as reported) |  | Net
September 30, 2025 |  |  |  |  |  |  |  |  |  |  |
Derivative assets | $82 |  | $72 |  | $52 |  | $47 |  | $30 |  | $25
Derivative liabilities | 48 |  | 38 |  | 10 |  | 5 |  | 38 |  | 33
December 31, 2024 |  |  |  |  |  |  |  |  |  |  |
Derivative assets | 75 |  | 64 |  | 48 |  | 43 |  | 27 |  | 21
Derivative liabilities | 58 |  | 47 |  | 13 |  | 8 |  | 45 |  | 39
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.

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