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Fair Value Measurements

9 Months Ended

Sep. 30, 2025

FAIR VALUE MEASUREMENTS

Fair Value of Financial Instruments - The carrying amounts of current assets and current liabilities approximate fair value because of the short maturity of such financial instruments. Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions):


Alliant Energy	September 30, 2025					December 31, 2024
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$477	$477	$—	$—	$477	$52	$52	$—	$—	$52
Time deposits	250	—	250	—	250	—	—	—	—	—
Commodity derivatives	82	—	42	40	82	75	—	48	27	75

Deferred proceeds	231	—	—	231	231	163	—	—	163	163
Liabilities:
Commodity derivatives	48	—	47	1	48	58	—	56	2	58

Long-term debt (incl. current maturities)	11,729	—	11,504	—	11,504	9,848	—	9,577	—	9,577


IPL	September 30, 2025					December 31, 2024
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$194	$194	$—	$—	$194	$9	$9	$—	$—	$9
Commodity derivatives	52	—	21	31	52	48	—	26	22	48
Deferred proceeds	231	—	—	231	231	163	—	—	163	163
Liabilities:
Commodity derivatives	10	—	9	1	10	13	—	11	2	13
Long-term debt (incl. current maturities)	4,679	—	4,465	—	4,465	4,090	—	3,736	—	3,736


WPL	September 30, 2025					December 31, 2024
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$—	$—	$—	$—	$—	$43	$43	$—	$—	$43
Commodity derivatives	30	—	21	9	30	27	—	22	5	27
Liabilities:
Commodity derivatives	38	—	38	—	38	45	—	45	—	45
Long-term debt	3,372	—	3,287	—	3,287	3,370	—	3,170	—	3,170

Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):


Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2025	2024	2025	2024
Beginning balance, July 1	$56	$51	$235	$171
Total net gains (losses) included in changes in net assets (realized/unrealized)	(2)	2	—	—



Sales	(2)	—	—	—
Settlements (a)	(13)	(16)	(4)	41
Ending balance, September 30	$39	$37	$231	$212
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	($4)	$2	$—	$—



Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2025	2024	2025	2024
Beginning balance, January 1	$25	$24	$163	$216
Total net gains (losses) included in changes in net assets (realized/unrealized)	5	(7)	—	—


Purchases	50	59	—	—
Sales	(2)	(1)	—	—
Settlements (a)	(39)	(38)	68	(4)
Ending balance, September 30	$39	$37	$231	$212
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$4	($7)	$—	$—


IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2025	2024	2025	2024
Beginning balance, July 1	$44	$40	$235	$171
Total net losses included in changes in net assets (realized/unrealized)	(5)	—	—	—



Sales	(1)	—	—	—
Settlements (a)	(8)	(11)	(4)	41
Ending balance, September 30	$30	$29	$231	$212
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at September 30	($6)	$—	$—	$—



IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2025	2024	2025	2024
Beginning balance, January 1	$20	$19	$163	$216
Total net gains (losses) included in changes in net assets (realized/unrealized)	1	(7)	—	—


Purchases	40	45	—	—
Sales	(1)	(1)	—	—
Settlements (a)	(30)	(27)	68	(4)
Ending balance, September 30	$30	$29	$231	$212
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$1	($7)	$—	$—


WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Three Months Ended September 30	2025	2024
Beginning balance, July 1	$12	$11
Total net gains included in changes in net assets (realized/unrealized)	3	2



Sales	(1)	—
Settlements	(5)	(5)
Ending balance, September 30	$9	$8
The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at September 30	$2	$2



WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Nine Months Ended September 30	2025	2024
Beginning balance, January 1	$5	$5
Total net gains included in changes in net assets (realized/unrealized)	4	—


Purchases	10	14
Sales	(1)	—
Settlements	(9)	(11)
Ending balance, September 30	$9	$8
The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at September 30	$3	$—

(a)Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for expected credit losses associated with the receivables sold and cash amounts received from the receivables sold.

Commodity Contracts - The fair value of FTRs and natural gas commodity contracts categorized as Level 3 was recognized as net derivative assets as follows (in millions):


	Alliant Energy		IPL		WPL
	Excluding FTRs	FTRs	Excluding FTRs	FTRs	Excluding FTRs	FTRs
September 30, 2025	$3	$36	$3	$27	$—	$9
December 31, 2024	—	25	—	20	—	5

IPL [Member]

Fair Value Measurements

FAIR VALUE MEASUREMENTS


Alliant Energy	September 30, 2025					December 31, 2024
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$477	$477	$—	$—	$477	$52	$52	$—	$—	$52
Time deposits	250	—	250	—	250	—	—	—	—	—
Commodity derivatives	82	—	42	40	82	75	—	48	27	75

Deferred proceeds	231	—	—	231	231	163	—	—	163	163
Liabilities:
Commodity derivatives	48	—	47	1	48	58	—	56	2	58

Long-term debt (incl. current maturities)	11,729	—	11,504	—	11,504	9,848	—	9,577	—	9,577


IPL	September 30, 2025					December 31, 2024
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$194	$194	$—	$—	$194	$9	$9	$—	$—	$9
Commodity derivatives	52	—	21	31	52	48	—	26	22	48
Deferred proceeds	231	—	—	231	231	163	—	—	163	163
Liabilities:
Commodity derivatives	10	—	9	1	10	13	—	11	2	13
Long-term debt (incl. current maturities)	4,679	—	4,465	—	4,465	4,090	—	3,736	—	3,736


WPL	September 30, 2025					December 31, 2024
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$—	$—	$—	$—	$—	$43	$43	$—	$—	$43
Commodity derivatives	30	—	21	9	30	27	—	22	5	27
Liabilities:
Commodity derivatives	38	—	38	—	38	45	—	45	—	45
Long-term debt	3,372	—	3,287	—	3,287	3,370	—	3,170	—	3,170

Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):


Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2025	2024	2025	2024
Beginning balance, July 1	$56	$51	$235	$171
Total net gains (losses) included in changes in net assets (realized/unrealized)	(2)	2	—	—



Sales	(2)	—	—	—
Settlements (a)	(13)	(16)	(4)	41
Ending balance, September 30	$39	$37	$231	$212
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	($4)	$2	$—	$—



Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2025	2024	2025	2024
Beginning balance, January 1	$25	$24	$163	$216
Total net gains (losses) included in changes in net assets (realized/unrealized)	5	(7)	—	—


Purchases	50	59	—	—
Sales	(2)	(1)	—	—
Settlements (a)	(39)	(38)	68	(4)
Ending balance, September 30	$39	$37	$231	$212
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$4	($7)	$—	$—


IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2025	2024	2025	2024
Beginning balance, July 1	$44	$40	$235	$171
Total net losses included in changes in net assets (realized/unrealized)	(5)	—	—	—



Sales	(1)	—	—	—
Settlements (a)	(8)	(11)	(4)	41
Ending balance, September 30	$30	$29	$231	$212
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at September 30	($6)	$—	$—	$—



IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2025	2024	2025	2024
Beginning balance, January 1	$20	$19	$163	$216
Total net gains (losses) included in changes in net assets (realized/unrealized)	1	(7)	—	—


Purchases	40	45	—	—
Sales	(1)	(1)	—	—
Settlements (a)	(30)	(27)	68	(4)
Ending balance, September 30	$30	$29	$231	$212
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$1	($7)	$—	$—


WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Three Months Ended September 30	2025	2024
Beginning balance, July 1	$12	$11
Total net gains included in changes in net assets (realized/unrealized)	3	2



Sales	(1)	—
Settlements	(5)	(5)
Ending balance, September 30	$9	$8
The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at September 30	$2	$2



WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Nine Months Ended September 30	2025	2024
Beginning balance, January 1	$5	$5
Total net gains included in changes in net assets (realized/unrealized)	4	—


Purchases	10	14
Sales	(1)	—
Settlements	(9)	(11)
Ending balance, September 30	$9	$8
The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at September 30	$3	$—

Commodity Contracts - The fair value of FTRs and natural gas commodity contracts categorized as Level 3 was recognized as net derivative assets as follows (in millions):


	Alliant Energy		IPL		WPL
	Excluding FTRs	FTRs	Excluding FTRs	FTRs	Excluding FTRs	FTRs
September 30, 2025	$3	$36	$3	$27	$—	$9
December 31, 2024	—	25	—	20	—	5

WPL [Member]

Fair Value Measurements

FAIR VALUE MEASUREMENTS


Alliant Energy	September 30, 2025					December 31, 2024
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$477	$477	$—	$—	$477	$52	$52	$—	$—	$52
Time deposits	250	—	250	—	250	—	—	—	—	—
Commodity derivatives	82	—	42	40	82	75	—	48	27	75

Deferred proceeds	231	—	—	231	231	163	—	—	163	163
Liabilities:
Commodity derivatives	48	—	47	1	48	58	—	56	2	58

Long-term debt (incl. current maturities)	11,729	—	11,504	—	11,504	9,848	—	9,577	—	9,577


IPL	September 30, 2025					December 31, 2024
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$194	$194	$—	$—	$194	$9	$9	$—	$—	$9
Commodity derivatives	52	—	21	31	52	48	—	26	22	48
Deferred proceeds	231	—	—	231	231	163	—	—	163	163
Liabilities:
Commodity derivatives	10	—	9	1	10	13	—	11	2	13
Long-term debt (incl. current maturities)	4,679	—	4,465	—	4,465	4,090	—	3,736	—	3,736


WPL	September 30, 2025					December 31, 2024
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$—	$—	$—	$—	$—	$43	$43	$—	$—	$43
Commodity derivatives	30	—	21	9	30	27	—	22	5	27
Liabilities:
Commodity derivatives	38	—	38	—	38	45	—	45	—	45
Long-term debt	3,372	—	3,287	—	3,287	3,370	—	3,170	—	3,170

Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):


Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2025	2024	2025	2024
Beginning balance, July 1	$56	$51	$235	$171
Total net gains (losses) included in changes in net assets (realized/unrealized)	(2)	2	—	—



Sales	(2)	—	—	—
Settlements (a)	(13)	(16)	(4)	41
Ending balance, September 30	$39	$37	$231	$212
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	($4)	$2	$—	$—



Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2025	2024	2025	2024
Beginning balance, January 1	$25	$24	$163	$216
Total net gains (losses) included in changes in net assets (realized/unrealized)	5	(7)	—	—


Purchases	50	59	—	—
Sales	(2)	(1)	—	—
Settlements (a)	(39)	(38)	68	(4)
Ending balance, September 30	$39	$37	$231	$212
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$4	($7)	$—	$—


IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2025	2024	2025	2024
Beginning balance, July 1	$44	$40	$235	$171
Total net losses included in changes in net assets (realized/unrealized)	(5)	—	—	—



Sales	(1)	—	—	—
Settlements (a)	(8)	(11)	(4)	41
Ending balance, September 30	$30	$29	$231	$212
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at September 30	($6)	$—	$—	$—



IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2025	2024	2025	2024
Beginning balance, January 1	$20	$19	$163	$216
Total net gains (losses) included in changes in net assets (realized/unrealized)	1	(7)	—	—


Purchases	40	45	—	—
Sales	(1)	(1)	—	—
Settlements (a)	(30)	(27)	68	(4)
Ending balance, September 30	$30	$29	$231	$212
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$1	($7)	$—	$—


WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Three Months Ended September 30	2025	2024
Beginning balance, July 1	$12	$11
Total net gains included in changes in net assets (realized/unrealized)	3	2



Sales	(1)	—
Settlements	(5)	(5)
Ending balance, September 30	$9	$8
The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at September 30	$2	$2



WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Nine Months Ended September 30	2025	2024
Beginning balance, January 1	$5	$5
Total net gains included in changes in net assets (realized/unrealized)	4	—


Purchases	10	14
Sales	(1)	—
Settlements	(9)	(11)
Ending balance, September 30	$9	$8
The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at September 30	$3	$—

Commodity Contracts - The fair value of FTRs and natural gas commodity contracts categorized as Level 3 was recognized as net derivative assets as follows (in millions):


	Alliant Energy		IPL		WPL
	Excluding FTRs	FTRs	Excluding FTRs	FTRs	Excluding FTRs	FTRs
September 30, 2025	$3	$36	$3	$27	$—	$9
December 31, 2024	—	25	—	20	—	5

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References

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+ Details