ALLIANT ENERGY CORPLNT
ALLIANT ENERGY CORP Debt Disclosure
DEBT(a) Short-term Debt - Alliant Energy and its subsidiaries maintain committed bank lines of credit to provide short-term borrowing flexibility and back-stop liquidity for commercial paper outstanding. At December 31, 2025, the short-term borrowing capacity under a single credit facility agreement, which expires in December 2030, totaled $1.3 billion ($550 million for Alliant Energy at the parent company level, $350 million for IPL and $400 million for WPL). Subject to certain conditions, Alliant Energy (at the parent company level), IPL and WPL may each reallocate and change its sublimit up to $1 billion, $400 million and $500 million, respectively, within the $1.3 billion total commitment. Information regarding Alliant Energy’s, IPL’s and WPL’s commercial paper and borrowings under the single credit facility classified as short-term debt was as follows (dollars in millions):
(b) Long-Term Debt - Long-term debt, net as of December 31 was as follows (dollars in millions):
| Alliant Energy | IPL | WPL | |||||||||||||||||||||||||||||||||
| December 31 | 2025 | 2024 | 2025 | 2024 | 2025 | 2024 | |||||||||||||||||||||||||||||
| Amount outstanding | $88 | $558 | $88 | $50 | $— | $183 | |||||||||||||||||||||||||||||
| Weighted average interest rates | 3.8% | 4.5% | 3.8% | 4.6% | N/A | 4.5% | |||||||||||||||||||||||||||||
| Available credit facility capacity | $1,212 | $742 | $262 | $250 | $400 | $217 | |||||||||||||||||||||||||||||
| Alliant Energy | IPL | WPL | |||||||||||||||||||||||||||||||||
| For the year ended | 2025 | 2024 | 2025 | 2024 | 2025 | 2024 | |||||||||||||||||||||||||||||
| Maximum amount outstanding (based on daily outstanding balances) | $741 | $632 | $141 | $80 | $297 | $390 | |||||||||||||||||||||||||||||
| Average amount outstanding (based on daily outstanding balances) | $349 | $327 | $25 | $1 | $176 | $70 | |||||||||||||||||||||||||||||
| Weighted average interest rates | 4.5% | 5.3% | 4.6% | 5.1% | 4.5% | 5.4% | |||||||||||||||||||||||||||||
| 2025 | 2024 | ||||||||||||||||||||||||||||||||||
| Alliant Energy | IPL | WPL | Alliant Energy | IPL | WPL | ||||||||||||||||||||||||||||||
| Senior Debentures (a): | |||||||||||||||||||||||||||||||||||
4.1%, due 2028 | $ | 500 | $ | 500 | $ | — | $ | 500 | $ | 500 | $ | — | |||||||||||||||||||||||
3.6%, due 2029 | 300 | 300 | — | 300 | 300 | — | |||||||||||||||||||||||||||||
2.3%, due 2030 | 400 | 400 | — | 400 | 400 | — | |||||||||||||||||||||||||||||
5.7%, due 2033 | 300 | 300 | — | 300 | 300 | — | |||||||||||||||||||||||||||||
6.45%, due 2033 | 100 | 100 | — | 100 | 100 | — | |||||||||||||||||||||||||||||
4.95%, due 2034 | 350 | 350 | — | 350 | 350 | — | |||||||||||||||||||||||||||||
6.3%, due 2034 | 125 | 125 | — | 125 | 125 | — | |||||||||||||||||||||||||||||
5.6%, due 2035 (b) | 600 | 600 | — | — | — | — | |||||||||||||||||||||||||||||
6.25%, due 2039 | 300 | 300 | — | 300 | 300 | — | |||||||||||||||||||||||||||||
4.7%, due 2043 | 250 | 250 | — | 250 | 250 | — | |||||||||||||||||||||||||||||
3.7%, due 2046 | 300 | 300 | — | 300 | 300 | — | |||||||||||||||||||||||||||||
3.5%, due 2049 | 300 | 300 | — | 300 | 300 | — | |||||||||||||||||||||||||||||
3.1%, due 2051 | 300 | 300 | — | 300 | 300 | — | |||||||||||||||||||||||||||||
5.45%, due 2054 | 300 | 300 | — | 300 | 300 | — | |||||||||||||||||||||||||||||
5.6%, due 2055 (b) | 300 | 300 | — | — | — | — | |||||||||||||||||||||||||||||
3.4%, (Retired in 2025) | — | — | — | 250 | 250 | — | |||||||||||||||||||||||||||||
5.5%, (Retired in 2025) | — | — | — | 50 | 50 | — | |||||||||||||||||||||||||||||
| 4,725 | 4,725 | — | 4,125 | 4,125 | — | ||||||||||||||||||||||||||||||
| Debentures (a): | |||||||||||||||||||||||||||||||||||
3.05%, due 2027 | 300 | — | 300 | 300 | — | 300 | |||||||||||||||||||||||||||||
3%, due 2029 | 350 | — | 350 | 350 | — | 350 | |||||||||||||||||||||||||||||
1.95%, due 2031 | 300 | — | 300 | 300 | — | 300 | |||||||||||||||||||||||||||||
3.95%, due 2032 | 600 | — | 600 | 600 | — | 600 | |||||||||||||||||||||||||||||
4.95%, due 2033 | 300 | — | 300 | 300 | — | 300 | |||||||||||||||||||||||||||||
5.375%, due 2034 | 300 | — | 300 | 300 | — | 300 | |||||||||||||||||||||||||||||
6.25%, due 2034 | 100 | — | 100 | 100 | — | 100 | |||||||||||||||||||||||||||||
6.375%, due 2037 | 300 | — | 300 | 300 | — | 300 | |||||||||||||||||||||||||||||
7.6%, due 2038 | 250 | — | 250 | 250 | — | 250 | |||||||||||||||||||||||||||||
4.1%, due 2044 | 250 | — | 250 | 250 | — | 250 | |||||||||||||||||||||||||||||
3.65%, due 2050 | 350 | — | 350 | 350 | — | 350 | |||||||||||||||||||||||||||||
5.7%, due 2055 (c) | 300 | — | 300 | — | — | — | |||||||||||||||||||||||||||||
| 3,700 | — | 3,700 | 3,400 | — | 3,400 | ||||||||||||||||||||||||||||||
| Other: | |||||||||||||||||||||||||||||||||||
AEF term loan credit agreement through March 2026, 5% at December 31, 2025 (with Alliant Energy as guarantor) (d) | 300 | — | — | — | — | — | |||||||||||||||||||||||||||||
AEF 1.4% senior notes, due 2026 (with Alliant Energy as guarantor) (a) | 200 | — | — | 200 | — | — | |||||||||||||||||||||||||||||
Alliant Energy 3.875% convertible senior notes, due 2026 (e) | 575 | — | — | 575 | — | — | |||||||||||||||||||||||||||||
AEF 5.4% senior notes, due 2027 (with Alliant Energy as guarantor) (a) | 375 | — | — | 375 | — | — | |||||||||||||||||||||||||||||
Alliant Energy 3.25% convertible senior notes, due 2028 (e) | 575 | — | — | — | — | — | |||||||||||||||||||||||||||||
AEF 4.25% senior notes, due 2028 (with Alliant Energy as guarantor) (a) | 300 | — | — | 300 | — | — | |||||||||||||||||||||||||||||
AEF 5.95% senior notes, due 2029 (with Alliant Energy as guarantor) (a) | 300 | — | — | 300 | — | — | |||||||||||||||||||||||||||||
AEF 3.6% senior notes, due 2032 (with Alliant Energy as guarantor) (a) | 350 | — | — | 350 | — | — | |||||||||||||||||||||||||||||
Alliant Energy 5.75% junior subordinated notes, due 2056 (f) | 725 | — | — | — | — | — | |||||||||||||||||||||||||||||
AEF term loan credit agreement, 6% at December 31, 2024 (with Alliant Energy as guarantor) (Retired in 2025) (d) | — | — | — | 300 | — | — | |||||||||||||||||||||||||||||
| 3,700 | — | — | 2,400 | — | — | ||||||||||||||||||||||||||||||
| Subtotal | 12,125 | 4,725 | 3,700 | 9,925 | 4,125 | 3,400 | |||||||||||||||||||||||||||||
| Current maturities | (1,074) | — | — | (1,171) | (300) | — | |||||||||||||||||||||||||||||
| Unamortized debt issuance costs | (70) | (30) | (21) | (55) | (25) | (20) | |||||||||||||||||||||||||||||
| Unamortized debt (discount) and premium, net | (27) | (15) | (10) | (22) | (10) | (10) | |||||||||||||||||||||||||||||
| Long-term debt, net (g) | $10,954 | $4,680 | $3,669 | $8,677 | $3,790 | $3,370 | |||||||||||||||||||||||||||||
(a)Contains optional redemption provisions which, if elected by the issuer at its sole discretion, could require material redemption premium payments by the issuer. The redemption premium payments under these optional redemption provisions are variable and dependent on applicable U.S. Treasury rates at the time of redemption.
(b)In May 2025, IPL issued $600 million of 5.6% senior debentures due 2035. A portion of the net proceeds was used for the retirement of IPL’s $50 million 5.5% senior debentures and $250 million 3.4% senior debentures. The remainder of the proceeds were used to reduce cash amounts received from its sale of accounts receivable program and commercial paper classified as long-term debt, and for general corporate purposes. In September 2025, IPL issued $300 million of 5.6% senior debentures due 2055. The net proceeds were used to reduce cash amounts received from its sale of accounts receivable program, to reduce outstanding commercial paper, and for general corporate purposes.
(c)In December 2025, WPL issued $300 million of 5.7% debentures due 2055. The net proceeds were used to reduce outstanding commercial paper and for general corporate purposes.
(d)In March 2025, AEF entered into a $300 million variable rate term loan credit agreement, which amended and restated the term loan credit agreement that expired in March 2025, and retired the $300 million variable rate term loan set forth therein, which was classified as a non-cash financing activity. AEF’s restated agreement includes an option to increase the amount outstanding with one or more additional term loans in an aggregate amount not to exceed $100 million. Refer to Note 14 for information on AEF’s related interest rate swap. In January 2026, AEF retired its $300 million term loan.
(f)In September 2025, Alliant Energy issued $725 million of junior subordinated notes due 2056. The interest rate will reset every 5 years beginning April 1, 2031, to equal the then-current five-year U.S. Treasury rate plus a spread of 2.077%, provided the interest rate will not reset below 5.75%. The net proceeds were used to reduce outstanding commercial paper, retire long term debt and for general corporate purposes. Long term debt to be retired includes AEF’s $300 million variable rate term loan which was retired in January 2026, AEF’s $200 million of 1.4% senior notes and Alliant Energy’s $575 million of 3.875% convertible senior notes, each of which matures in March 2026 and is expected to be retired at or prior to maturity. Alliant Energy has the option to redeem the notes prior to maturity upon the occurrence of certain events and during specified periods, at redemption prices specified in the governing agreements.
(g)There were no significant sinking fund requirements related to the outstanding long-term debt.
Convertible Senior Notes
2026 Notes - In March 2023, Alliant Energy issued $575 million of 3.875% convertible senior notes (the 2026 Notes), which are senior unsecured obligations, and used the net proceeds from the issuance for general corporate purposes. The 2026 Notes will mature on March 15, 2026 unless earlier converted or repurchased. Alliant Energy may not redeem the 2026 Notes prior to the maturity date. Holders could have converted their 2026 Notes at their option at any time prior to the close of business on the business day immediately preceding December 15, 2025 only under the following circumstances:
•during any calendar quarter commencing after the calendar quarter ending on June 30, 2023 (and only during such calendar quarter), if the last reported sale price of Alliant Energy’s common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day during such period;
•during the 5 business day period after any 10 consecutive trading day period (the “measurement period”) in which the trading price (as defined in the related Indenture) per $1,000 principal amount of 2026 Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of Alliant Energy’s common stock and the conversion rate on each such trading day; or
•upon the occurrence of specified corporate events.
On or after December 15, 2025 until the close of business on the business day immediately preceding the maturity date, holders may convert all or any portion of their 2026 Notes at any time, regardless of the foregoing circumstances. Upon conversion of the 2026 Notes, Alliant Energy will pay cash up to the aggregate principal amount of the 2026 Notes to be converted and deliver shares of its common stock, in respect of the remainder, if any, of its conversion obligation in excess of the aggregate principal amount of the 2026 Notes being converted.
The initial conversion rate is 15.5461 shares of common stock per $1,000 principal amount of 2026 Notes (equivalent to an initial conversion price of approximately $64.32 per share of Alliant Energy’s common stock). The conversion rate is subject to adjustment in some events but will not be adjusted for any accrued and unpaid interest. In addition, following certain corporate events that occur prior to the maturity date, Alliant Energy will, in certain circumstances, increase the conversion rate for a holder who elects to convert its 2026 Notes in connection with such a corporate event.
If Alliant Energy undergoes a fundamental change (as defined in the related Indenture), then, subject to certain conditions, holders of the 2026 Notes may require Alliant Energy to repurchase for cash all or any portion of its 2026 Notes at a fundamental change repurchase price equal to 100% of the principal amount of the 2026 Notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change repurchase date.
As of December 31, 2025 and 2024, the 2026 Notes were classified on Alliant Energy’s balance sheets as “Current maturities of long-term debt”. As of December 31, 2025 and 2024, the net carrying amount of the 2026 Notes was $574 million and $571 million, with unamortized debt issuance costs of $1 million and $4 million, and the estimated fair value (Level 2) of the 2026 Notes was $599 million and $591 million. As of December 31, 2025, there were 407,821 shares of Alliant Energy’s common stock related to the potential conversion of the 2026 Notes included in diluted EPS based on Alliant Energy’s average stock prices and the relevant terms of the 2026 Notes.
2028 Notes - In May 2025, Alliant Energy issued $575 million of 3.25% convertible senior notes (the 2028 Notes), which are senior unsecured obligations, and used the net proceeds from the issuance to reduce Alliant Energy’s outstanding commercial paper and for general corporate purposes. The 2028 Notes will mature on May 30, 2028 unless earlier converted or repurchased, and no sinking fund is provided for the 2028 Notes. Alliant Energy may not redeem the 2028 Notes prior to the maturity date. Holders may convert their 2028 Notes at their option at any time prior to the close of business on the business day immediately preceding March 1, 2028 only under the following circumstances:
•during any calendar quarter commencing after the calendar quarter ending on September 30, 2025 (and only during such calendar quarter), if the last reported sale price of Alliant Energy’s common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day during such period;
•during the 5 business day period after any 10 consecutive trading day period (the “measurement period”) in which the trading price (as defined in the related Indenture) per $1,000 principal amount of 2028 Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of Alliant Energy’s common stock and the conversion rate on each such trading day; or
•upon the occurrence of specified corporate events.
On or after March 1, 2028 until the close of business on the business day immediately preceding the maturity date, holders may convert all or any portion of their 2028 Notes at any time, regardless of the foregoing circumstances. Upon conversion of the 2028 Notes, Alliant Energy will pay cash up to the aggregate principal amount of the 2028 Notes to be converted and pay or deliver, as the case may be, cash, shares of its common stock or a combination of cash and shares of its common stock, at its election, in respect of the remainder, if any, of its conversion obligation in excess of the aggregate principal amount of the 2028 Notes being converted.
The initial conversion rate is 13.1773 shares of common stock per $1,000 principal amount of 2028 Notes (equivalent to an initial conversion price of approximately $75.89 per share of Alliant Energy’s common stock). The conversion rate is subject to adjustment in some events but will not be adjusted for any accrued and unpaid interest. In addition, following certain corporate events that occur prior to the maturity date, Alliant Energy will, in certain circumstances, increase the conversion rate for a holder who elects to convert its 2028 Notes in connection with such a corporate event.
If Alliant Energy undergoes a fundamental change (as defined in the related Indenture), then, subject to certain conditions, holders of the 2028 Notes may require Alliant Energy to repurchase for cash all or any portion of its 2028 Notes at a fundamental change repurchase price equal to 100% of the principal amount of the 2028 Notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change repurchase date.
As of December 31, 2025, the conditions allowing holders of the 2028 Notes to convert their 2028 Notes were not met, and the 2028 Notes were classified as “Long-term debt, net” on Alliant Energy’s balance sheet. As of December 31, 2025, the net carrying amount was $569 million, with unamortized debt issuance costs of $6 million, and the estimated fair value (Level 2) was $587 million for the 2028 Notes. As of December 31, 2025, there were no shares of Alliant Energy’s common stock related to the potential conversion of the 2028 Notes included in diluted EPS based on Alliant Energy’s average stock prices and the relevant terms of the 2028 Notes.
Five-Year Schedule of Long-term Debt Maturities - At December 31, 2025, long-term debt maturities for 2026 through 2030 were as follows (in millions):
| 2026 | 2027 | 2028 | 2029 | 2030 | |||||||||||||||||||||||||
| IPL | $— | $— | $500 | $300 | $400 | ||||||||||||||||||||||||
| WPL | — | 300 | — | 350 | — | ||||||||||||||||||||||||
| AEF | 500 | 375 | 300 | 300 | — | ||||||||||||||||||||||||
| Alliant Energy parent company | 575 | — | 575 | — | — | ||||||||||||||||||||||||
| Alliant Energy | $1,075 | $675 | $1,375 | $950 | $400 | ||||||||||||||||||||||||
Historical Timeline
| Fiscal Year | Filed | |
|---|---|---|
| 2025 | Feb 20, 2026 | Showing above |
| 2024 | Feb 21, 2025 | |
| 2023 | Feb 16, 2024 | |
| 2022 | Feb 24, 2023 | |
| 2021 | Feb 18, 2022 | |
| 2020 | Feb 19, 2021 | |
About Debt Disclosures
Debt disclosures detail a company's borrowing structure — the types of instruments, interest rates, maturity schedule, and covenant restrictions that define its financial obligations and flexibility. This section is essential for assessing refinancing risk, interest rate exposure, and the margin of safety against financial distress.
Key signals: the maturity schedule reveals concentration risk — large maturities within 1-2 years during tight credit markets can force dilutive refinancing or asset sales. Compare the fair value of debt against carrying amount to gauge whether the market views the company's credit risk differently than the balance sheet suggests. Watch covenant compliance disclosures for tightening cushions, especially leverage and interest coverage ratios. Variable-rate debt exposure quantifies sensitivity to interest rate changes. Secured versus unsecured mix affects recovery rates and future borrowing capacity. Compare net debt-to-EBITDA against industry peers and covenant limits to assess financial health.