v3.25.2
Fair Value Measurements (Tables)
 6 Months Ended
Jun. 30, 2025
Statement [Line Items]  
Fair Value Measurements Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions):
Alliant EnergyJune 30, 2025December 31, 2024
Fair ValueFair Value
CarryingLevelLevelLevelCarryingLevelLevelLevel
Amount123TotalAmount123Total
Assets:
Money market fund investments and time deposits$303 $303 $— $— $303 $52 $52 $— $— $52 
Commodity derivatives105 — 48 57 105 75 — 48 27 75 
Deferred proceeds235 — — 235 235 163 — — 163 163 
Liabilities:
Commodity derivatives53 — 52 1 53 58 — 56 2 58 
Long-term debt (incl. current maturities)11,015 — 10,617 — 10,617 9,848 — 9,577 — 9,577 
IPLJune 30, 2025December 31, 2024
Fair ValueFair Value
CarryingLevelLevelLevelCarryingLevelLevelLevel
Amount123TotalAmount123Total
Assets:
Money market fund investments and time deposits$194 $194 $— $— $194 $9 $9 $— $— $9 
Commodity derivatives69 — 24 45 69 48 — 26 22 48 
Deferred proceeds235 — — 235 235 163 — — 163 163 
Liabilities:
Commodity derivatives12 — 11 1 12 13 — 11 2 13 
Long-term debt (incl. current maturities)4,684 — 4,408 — 4,408 4,090 — 3,736 — 3,736 
WPLJune 30, 2025December 31, 2024
Fair ValueFair Value
CarryingLevelLevelLevelCarryingLevelLevelLevel
Amount123TotalAmount123Total
Assets:
Money market fund investments$— $— $— $— $— $43 $43 $— $— $43 
Commodity derivatives36 — 24 12 36 27 — 22 5 27 
Liabilities:
Commodity derivatives41 — 41 — 41 45 — 45 — 45 
Long-term debt3,371 — 3,238 — 3,238 3,370 — 3,170 — 3,170 
Fair Value Measurements Using Significant Unobservable Inputs
Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):
Alliant EnergyCommodity Contract Derivative
Assets and (Liabilities), netDeferred Proceeds
Three Months Ended June 302025202420252024
Beginning balance, April 1 $9$7$86$184
Total net gains (losses) included in changes in net assets (realized/unrealized)
10(5)——
Purchases5059——
Sales(1)(1)——
Settlements (a)(12)(9)149(13)
Ending balance, June 30
$56$51$235$171
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 June 30
$10($5)$—$—
Alliant EnergyCommodity Contract Derivative
Assets and (Liabilities), netDeferred Proceeds
Six Months Ended June 302025202420252024
Beginning balance, January 1$25$24$163$216
Total net gains (losses) included in changes in net assets (realized/unrealized)
8(8)——
Purchases5059——
Sales(1)(1)——
Settlements (a)(26)(23)72(45)
Ending balance, June 30
$56$51$235$171
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 June 30
$8($8)$—$—
IPLCommodity Contract Derivative
Assets and (Liabilities), netDeferred Proceeds
Three Months Ended June 302025202420252024
Beginning balance, April 1 $9$5$86$184
Total net gains (losses) included in changes in net assets (realized/unrealized)
6(2)——
Purchases4045——
Sales(1)(1)——
Settlements (a)(10)(7)149(13)
Ending balance, June 30
$44$40$235$171
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 June 30
$6($2)$—$—
IPLCommodity Contract Derivative
Assets and (Liabilities), netDeferred Proceeds
Six Months Ended June 302025202420252024
Beginning balance, January 1$20$19$163$216
Total net gains (losses) included in changes in net assets (realized/unrealized)
6(6)——
Purchases4045——
Sales(1)(1)——
Settlements (a)(21)(17)72(45)
Ending balance, June 30
$44$40$235$171
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 June 30
$6($6)$—$—
WPLCommodity Contract Derivative
Assets and (Liabilities), net
Three Months Ended June 3020252024
Beginning balance, April 1 $—$2
Total net gains (losses) included in changes in net assets (realized/unrealized)
4(3)
Purchases1014
Settlements(2)(2)
Ending balance, June 30
$12$11
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 June 30
$4($3)
WPLCommodity Contract Derivative
Assets and (Liabilities), net
Six Months Ended June 3020252024
Beginning balance, January 1$5$5
Total net gains (losses) included in changes in net assets (realized/unrealized)
2(2)
Purchases1014
Settlements(5)(6)
Ending balance, June 30
$12$11
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 June 30
$2($2)

(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.
Fair Value Of Net Derivative Assets (Liabilities) 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 EnergyIPLWPL
Excluding FTRsFTRsExcluding FTRsFTRsExcluding FTRsFTRs
June 30, 2025$6$50$6$38$—$12
December 31, 2024—25—20—5
IPL [Member]  
Statement [Line Items]  
Fair Value Measurements Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions):
Alliant EnergyJune 30, 2025December 31, 2024
Fair ValueFair Value
CarryingLevelLevelLevelCarryingLevelLevelLevel
Amount123TotalAmount123Total
Assets:
Money market fund investments and time deposits$303 $303 $— $— $303 $52 $52 $— $— $52 
Commodity derivatives105 — 48 57 105 75 — 48 27 75 
Deferred proceeds235 — — 235 235 163 — — 163 163 
Liabilities:
Commodity derivatives53 — 52 1 53 58 — 56 2 58 
Long-term debt (incl. current maturities)11,015 — 10,617 — 10,617 9,848 — 9,577 — 9,577 
IPLJune 30, 2025December 31, 2024
Fair ValueFair Value
CarryingLevelLevelLevelCarryingLevelLevelLevel
Amount123TotalAmount123Total
Assets:
Money market fund investments and time deposits$194 $194 $— $— $194 $9 $9 $— $— $9 
Commodity derivatives69 — 24 45 69 48 — 26 22 48 
Deferred proceeds235 — — 235 235 163 — — 163 163 
Liabilities:
Commodity derivatives12 — 11 1 12 13 — 11 2 13 
Long-term debt (incl. current maturities)4,684 — 4,408 — 4,408 4,090 — 3,736 — 3,736 
WPLJune 30, 2025December 31, 2024
Fair ValueFair Value
CarryingLevelLevelLevelCarryingLevelLevelLevel
Amount123TotalAmount123Total
Assets:
Money market fund investments$— $— $— $— $— $43 $43 $— $— $43 
Commodity derivatives36 — 24 12 36 27 — 22 5 27 
Liabilities:
Commodity derivatives41 — 41 — 41 45 — 45 — 45 
Long-term debt3,371 — 3,238 — 3,238 3,370 — 3,170 — 3,170 
Fair Value Measurements Using Significant Unobservable Inputs
Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):
Alliant EnergyCommodity Contract Derivative
Assets and (Liabilities), netDeferred Proceeds
Three Months Ended June 302025202420252024
Beginning balance, April 1 $9$7$86$184
Total net gains (losses) included in changes in net assets (realized/unrealized)
10(5)——
Purchases5059——
Sales(1)(1)——
Settlements (a)(12)(9)149(13)
Ending balance, June 30
$56$51$235$171
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 June 30
$10($5)$—$—
Alliant EnergyCommodity Contract Derivative
Assets and (Liabilities), netDeferred Proceeds
Six Months Ended June 302025202420252024
Beginning balance, January 1$25$24$163$216
Total net gains (losses) included in changes in net assets (realized/unrealized)
8(8)——
Purchases5059——
Sales(1)(1)——
Settlements (a)(26)(23)72(45)
Ending balance, June 30
$56$51$235$171
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 June 30
$8($8)$—$—
IPLCommodity Contract Derivative
Assets and (Liabilities), netDeferred Proceeds
Three Months Ended June 302025202420252024
Beginning balance, April 1 $9$5$86$184
Total net gains (losses) included in changes in net assets (realized/unrealized)
6(2)——
Purchases4045——
Sales(1)(1)——
Settlements (a)(10)(7)149(13)
Ending balance, June 30
$44$40$235$171
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 June 30
$6($2)$—$—
IPLCommodity Contract Derivative
Assets and (Liabilities), netDeferred Proceeds
Six Months Ended June 302025202420252024
Beginning balance, January 1$20$19$163$216
Total net gains (losses) included in changes in net assets (realized/unrealized)
6(6)——
Purchases4045——
Sales(1)(1)——
Settlements (a)(21)(17)72(45)
Ending balance, June 30
$44$40$235$171
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 June 30
$6($6)$—$—
WPLCommodity Contract Derivative
Assets and (Liabilities), net
Three Months Ended June 3020252024
Beginning balance, April 1 $—$2
Total net gains (losses) included in changes in net assets (realized/unrealized)
4(3)
Purchases1014
Settlements(2)(2)
Ending balance, June 30
$12$11
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 June 30
$4($3)
WPLCommodity Contract Derivative
Assets and (Liabilities), net
Six Months Ended June 3020252024
Beginning balance, January 1$5$5
Total net gains (losses) included in changes in net assets (realized/unrealized)
2(2)
Purchases1014
Settlements(5)(6)
Ending balance, June 30
$12$11
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 June 30
$2($2)

(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.
Fair Value Of Net Derivative Assets (Liabilities) 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 EnergyIPLWPL
Excluding FTRsFTRsExcluding FTRsFTRsExcluding FTRsFTRs
June 30, 2025$6$50$6$38$—$12
December 31, 2024—25—20—5
WPL [Member]  
Statement [Line Items]  
Fair Value Measurements Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions):
Alliant EnergyJune 30, 2025December 31, 2024
Fair ValueFair Value
CarryingLevelLevelLevelCarryingLevelLevelLevel
Amount123TotalAmount123Total
Assets:
Money market fund investments and time deposits$303 $303 $— $— $303 $52 $52 $— $— $52 
Commodity derivatives105 — 48 57 105 75 — 48 27 75 
Deferred proceeds235 — — 235 235 163 — — 163 163 
Liabilities:
Commodity derivatives53 — 52 1 53 58 — 56 2 58 
Long-term debt (incl. current maturities)11,015 — 10,617 — 10,617 9,848 — 9,577 — 9,577 
IPLJune 30, 2025December 31, 2024
Fair ValueFair Value
CarryingLevelLevelLevelCarryingLevelLevelLevel
Amount123TotalAmount123Total
Assets:
Money market fund investments and time deposits$194 $194 $— $— $194 $9 $9 $— $— $9 
Commodity derivatives69 — 24 45 69 48 — 26 22 48 
Deferred proceeds235 — — 235 235 163 — — 163 163 
Liabilities:
Commodity derivatives12 — 11 1 12 13 — 11 2 13 
Long-term debt (incl. current maturities)4,684 — 4,408 — 4,408 4,090 — 3,736 — 3,736 
WPLJune 30, 2025December 31, 2024
Fair ValueFair Value
CarryingLevelLevelLevelCarryingLevelLevelLevel
Amount123TotalAmount123Total
Assets:
Money market fund investments$— $— $— $— $— $43 $43 $— $— $43 
Commodity derivatives36 — 24 12 36 27 — 22 5 27 
Liabilities:
Commodity derivatives41 — 41 — 41 45 — 45 — 45 
Long-term debt3,371 — 3,238 — 3,238 3,370 — 3,170 — 3,170 
Fair Value Measurements Using Significant Unobservable Inputs
Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):
Alliant EnergyCommodity Contract Derivative
Assets and (Liabilities), netDeferred Proceeds
Three Months Ended June 302025202420252024
Beginning balance, April 1 $9$7$86$184
Total net gains (losses) included in changes in net assets (realized/unrealized)
10(5)——
Purchases5059——
Sales(1)(1)——
Settlements (a)(12)(9)149(13)
Ending balance, June 30
$56$51$235$171
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 June 30
$10($5)$—$—
Alliant EnergyCommodity Contract Derivative
Assets and (Liabilities), netDeferred Proceeds
Six Months Ended June 302025202420252024
Beginning balance, January 1$25$24$163$216
Total net gains (losses) included in changes in net assets (realized/unrealized)
8(8)——
Purchases5059——
Sales(1)(1)——
Settlements (a)(26)(23)72(45)
Ending balance, June 30
$56$51$235$171
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 June 30
$8($8)$—$—
IPLCommodity Contract Derivative
Assets and (Liabilities), netDeferred Proceeds
Three Months Ended June 302025202420252024
Beginning balance, April 1 $9$5$86$184
Total net gains (losses) included in changes in net assets (realized/unrealized)
6(2)——
Purchases4045——
Sales(1)(1)——
Settlements (a)(10)(7)149(13)
Ending balance, June 30
$44$40$235$171
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 June 30
$6($2)$—$—
IPLCommodity Contract Derivative
Assets and (Liabilities), netDeferred Proceeds
Six Months Ended June 302025202420252024
Beginning balance, January 1$20$19$163$216
Total net gains (losses) included in changes in net assets (realized/unrealized)
6(6)——
Purchases4045——
Sales(1)(1)——
Settlements (a)(21)(17)72(45)
Ending balance, June 30
$44$40$235$171
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 June 30
$6($6)$—$—
WPLCommodity Contract Derivative
Assets and (Liabilities), net
Three Months Ended June 3020252024
Beginning balance, April 1 $—$2
Total net gains (losses) included in changes in net assets (realized/unrealized)
4(3)
Purchases1014
Settlements(2)(2)
Ending balance, June 30
$12$11
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 June 30
$4($3)
WPLCommodity Contract Derivative
Assets and (Liabilities), net
Six Months Ended June 3020252024
Beginning balance, January 1$5$5
Total net gains (losses) included in changes in net assets (realized/unrealized)
2(2)
Purchases1014
Settlements(5)(6)
Ending balance, June 30
$12$11
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 June 30
$2($2)

(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.
Fair Value Of Net Derivative Assets (Liabilities) 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 EnergyIPLWPL
Excluding FTRsFTRsExcluding FTRsFTRsExcluding FTRsFTRs
June 30, 2025$6$50$6$38$—$12
December 31, 2024—25—20—5