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Common Equity (Tables)

9 Months Ended

Sep. 30, 2025

Schedule of Capitalization, Equity [Line Items]

Common Share Activity

A summary of Alliant Energy’s common stock activity was as follows:

Shares outstanding, January 1, 2025			256,690,222
Shareowner Direct Plan			277,090
Equity-based compensation plans			86,377
Shares outstanding, September 30, 2025			257,053,689

Changes in Shareowners' Equity

A summary of changes in shareowners’ equity was as follows (in millions):

Alliant Energy																					Accumulated						Shares in
									Additional												Other						Deferred												Total
			Common						Paid-In						Retained						Comprehensive						Compensation												Common
			Stock						Capital						Earnings						Income (Loss)						Trust												Equity
Three Months Ended September 30, 2025
Beginning balance, June 30, 2025			$3						$3,075						$4,080						$—						($13)												$7,145
Net income attributable to Alliant Energy common shareowners															281																								281
Common stock dividends ($0.5075 per share)															(130)																								(130)
Shareowner Direct Plan issuances									6																														6
Equity-based compensation plans and other									6																		(1)												5
Ending balance, September 30, 2025			$3						$3,087						$4,231						$—						($14)												$7,307
Three Months Ended September 30, 2024
Beginning balance, June 30, 2024			$3						$3,042						$3,755						$3						($12)												$6,791
Net income attributable to Alliant Energy common shareowners															295																								295
Common stock dividends ($0.48 per share)															(123)																								(123)
Shareowner Direct Plan issuances									6																														6
Equity-based compensation plans and other									4																		(1)												3
Other comprehensive loss, net of tax																					(4)																		(4)
Ending balance, September 30, 2024			$3						$3,052						$3,927						($1)						($13)												$6,968

Alliant Energy																					Accumulated						Shares in
									Additional												Other						Deferred												Total
			Common						Paid-In						Retained						Comprehensive						Compensation												Common
			Stock						Capital						Earnings						Income (Loss)						Trust												Equity
Nine Months Ended September 30, 2025
Beginning balance, December 31, 2024			$3						$3,060						$3,954						$1						($14)												$7,004
Net income attributable to Alliant Energy common shareowners															668																								668
Common stock dividends ($1.5225 per share)															(391)																								(391)
Shareowner Direct Plan issuances									18																														18
Equity-based compensation plans and other									9																														9
Other comprehensive loss, net of tax																					(1)																		(1)
Ending balance, September 30, 2025			$3						$3,087						$4,231						$—						($14)												$7,307
Nine Months Ended September 30, 2024
Beginning balance, December 31, 2023			$3						$3,030						$3,756						$1						($13)												$6,777
Net income attributable to Alliant Energy common shareowners															540																								540
Common stock dividends ($1.44 per share)															(369)																								(369)
Shareowner Direct Plan issuances									18																														18
Equity-based compensation plans and other									4																														4
Other comprehensive loss, net of tax																					(2)																		(2)
Ending balance, September 30, 2024			$3						$3,052						$3,927						($1)						($13)												$6,968

IPL									Additional																		Total
			Common						Paid-In						Retained												Common
			Stock						Capital						Earnings												Equity
Three Months Ended September 30, 2025
Beginning balance, June 30, 2025			$33						$3,357						$1,245												$4,635
Net income															165												165
Common stock dividends															(90)												(90)
Capital contributions from parent									140																		140
Ending balance, September 30, 2025			$33						$3,497						$1,320												$4,850
Three Months Ended September 30, 2024
Beginning balance, June 30, 2024			$33						$3,012						$1,035												$4,080
Net income															190												190
Common stock dividends															(50)												(50)
Capital contributions from parent									200																		200
Ending balance, September 30, 2024			$33						$3,212						$1,175												$4,420

IPL									Additional																		Total
			Common						Paid-In						Retained												Common
			Stock						Capital						Earnings												Equity
Nine Months Ended September 30, 2025
Beginning balance, December 31, 2024			$33						$3,212						$1,216												$4,461
Net income															374												374
Common stock dividends															(270)												(270)
Capital contributions from parent									285																		285
Ending balance, September 30, 2025			$33						$3,497						$1,320												$4,850
Nine Months Ended September 30, 2024
Beginning balance, December 31, 2023			$33						$2,887						$1,054												$3,974
Net income															272												272
Common stock dividends															(151)												(151)
Capital contributions from parent									325																		325
Ending balance, September 30, 2024			$33						$3,212						$1,175												$4,420

WPL									Additional																		Total
			Common						Paid-In						Retained												Common
			Stock						Capital						Earnings												Equity
Three Months Ended September 30, 2025
Beginning balance, June 30, 2025			$66						$2,533						$1,581												$4,180
Net income															123												123
Common stock dividends															(44)												(44)
Capital contributions from parent									80																		80
Ending balance, September 30, 2025			$66						$2,613						$1,660												$4,339
Three Months Ended September 30, 2024
Beginning balance, June 30, 2024			$66						$2,533						$1,411												$4,010
Net income															114												114
Common stock dividends															(49)												(49)
Ending balance, September 30, 2024			$66						$2,533						$1,476												$4,075

WPL									Additional																		Total
			Common						Paid-In						Retained												Common
			Stock						Capital						Earnings												Equity
Nine Months Ended September 30, 2025
Beginning balance, December 31, 2024			$66						$2,533						$1,502												$4,101
Net income															321												321
Common stock dividends															(163)												(163)
Capital contributions from parent									80																		80
Ending balance, September 30, 2025			$66						$2,613						$1,660												$4,339
Nine Months Ended September 30, 2024
Beginning balance, December 31, 2023			$66						$2,478						$1,353												$3,897
Net income															270												270
Common stock dividends															(147)												(147)
Capital contributions from parent									55																		55
Ending balance, September 30, 2024			$66						$2,533						$1,476												$4,075

IPL [Member]

Schedule of Capitalization, Equity [Line Items]

Changes in Shareowners' Equity

A summary of changes in shareowners’ equity was as follows (in millions):

Alliant Energy																					Accumulated						Shares in
									Additional												Other						Deferred												Total
			Common						Paid-In						Retained						Comprehensive						Compensation												Common
			Stock						Capital						Earnings						Income (Loss)						Trust												Equity
Three Months Ended September 30, 2025
Beginning balance, June 30, 2025			$3						$3,075						$4,080						$—						($13)												$7,145
Net income attributable to Alliant Energy common shareowners															281																								281
Common stock dividends ($0.5075 per share)															(130)																								(130)
Shareowner Direct Plan issuances									6																														6
Equity-based compensation plans and other									6																		(1)												5
Ending balance, September 30, 2025			$3						$3,087						$4,231						$—						($14)												$7,307
Three Months Ended September 30, 2024
Beginning balance, June 30, 2024			$3						$3,042						$3,755						$3						($12)												$6,791
Net income attributable to Alliant Energy common shareowners															295																								295
Common stock dividends ($0.48 per share)															(123)																								(123)
Shareowner Direct Plan issuances									6																														6
Equity-based compensation plans and other									4																		(1)												3
Other comprehensive loss, net of tax																					(4)																		(4)
Ending balance, September 30, 2024			$3						$3,052						$3,927						($1)						($13)												$6,968

Alliant Energy																					Accumulated						Shares in
									Additional												Other						Deferred												Total
			Common						Paid-In						Retained						Comprehensive						Compensation												Common
			Stock						Capital						Earnings						Income (Loss)						Trust												Equity
Nine Months Ended September 30, 2025
Beginning balance, December 31, 2024			$3						$3,060						$3,954						$1						($14)												$7,004
Net income attributable to Alliant Energy common shareowners															668																								668
Common stock dividends ($1.5225 per share)															(391)																								(391)
Shareowner Direct Plan issuances									18																														18
Equity-based compensation plans and other									9																														9
Other comprehensive loss, net of tax																					(1)																		(1)
Ending balance, September 30, 2025			$3						$3,087						$4,231						$—						($14)												$7,307
Nine Months Ended September 30, 2024
Beginning balance, December 31, 2023			$3						$3,030						$3,756						$1						($13)												$6,777
Net income attributable to Alliant Energy common shareowners															540																								540
Common stock dividends ($1.44 per share)															(369)																								(369)
Shareowner Direct Plan issuances									18																														18
Equity-based compensation plans and other									4																														4
Other comprehensive loss, net of tax																					(2)																		(2)
Ending balance, September 30, 2024			$3						$3,052						$3,927						($1)						($13)												$6,968

IPL									Additional																		Total
			Common						Paid-In						Retained												Common
			Stock						Capital						Earnings												Equity
Three Months Ended September 30, 2025
Beginning balance, June 30, 2025			$33						$3,357						$1,245												$4,635
Net income															165												165
Common stock dividends															(90)												(90)
Capital contributions from parent									140																		140
Ending balance, September 30, 2025			$33						$3,497						$1,320												$4,850
Three Months Ended September 30, 2024
Beginning balance, June 30, 2024			$33						$3,012						$1,035												$4,080
Net income															190												190
Common stock dividends															(50)												(50)
Capital contributions from parent									200																		200
Ending balance, September 30, 2024			$33						$3,212						$1,175												$4,420

IPL									Additional																		Total
			Common						Paid-In						Retained												Common
			Stock						Capital						Earnings												Equity
Nine Months Ended September 30, 2025
Beginning balance, December 31, 2024			$33						$3,212						$1,216												$4,461
Net income															374												374
Common stock dividends															(270)												(270)
Capital contributions from parent									285																		285
Ending balance, September 30, 2025			$33						$3,497						$1,320												$4,850
Nine Months Ended September 30, 2024
Beginning balance, December 31, 2023			$33						$2,887						$1,054												$3,974
Net income															272												272
Common stock dividends															(151)												(151)
Capital contributions from parent									325																		325
Ending balance, September 30, 2024			$33						$3,212						$1,175												$4,420

WPL									Additional																		Total
			Common						Paid-In						Retained												Common
			Stock						Capital						Earnings												Equity
Three Months Ended September 30, 2025
Beginning balance, June 30, 2025			$66						$2,533						$1,581												$4,180
Net income															123												123
Common stock dividends															(44)												(44)
Capital contributions from parent									80																		80
Ending balance, September 30, 2025			$66						$2,613						$1,660												$4,339
Three Months Ended September 30, 2024
Beginning balance, June 30, 2024			$66						$2,533						$1,411												$4,010
Net income															114												114
Common stock dividends															(49)												(49)
Ending balance, September 30, 2024			$66						$2,533						$1,476												$4,075

WPL									Additional																		Total
			Common						Paid-In						Retained												Common
			Stock						Capital						Earnings												Equity
Nine Months Ended September 30, 2025
Beginning balance, December 31, 2024			$66						$2,533						$1,502												$4,101
Net income															321												321
Common stock dividends															(163)												(163)
Capital contributions from parent									80																		80
Ending balance, September 30, 2025			$66						$2,613						$1,660												$4,339
Nine Months Ended September 30, 2024
Beginning balance, December 31, 2023			$66						$2,478						$1,353												$3,897
Net income															270												270
Common stock dividends															(147)												(147)
Capital contributions from parent									55																		55
Ending balance, September 30, 2024			$66						$2,533						$1,476												$4,075

WPL [Member]

Schedule of Capitalization, Equity [Line Items]

Changes in Shareowners' Equity

A summary of changes in shareowners’ equity was as follows (in millions):

Alliant Energy																					Accumulated						Shares in
									Additional												Other						Deferred												Total
			Common						Paid-In						Retained						Comprehensive						Compensation												Common
			Stock						Capital						Earnings						Income (Loss)						Trust												Equity
Three Months Ended September 30, 2025
Beginning balance, June 30, 2025			$3						$3,075						$4,080						$—						($13)												$7,145
Net income attributable to Alliant Energy common shareowners															281																								281
Common stock dividends ($0.5075 per share)															(130)																								(130)
Shareowner Direct Plan issuances									6																														6
Equity-based compensation plans and other									6																		(1)												5
Ending balance, September 30, 2025			$3						$3,087						$4,231						$—						($14)												$7,307
Three Months Ended September 30, 2024
Beginning balance, June 30, 2024			$3						$3,042						$3,755						$3						($12)												$6,791
Net income attributable to Alliant Energy common shareowners															295																								295
Common stock dividends ($0.48 per share)															(123)																								(123)
Shareowner Direct Plan issuances									6																														6
Equity-based compensation plans and other									4																		(1)												3
Other comprehensive loss, net of tax																					(4)																		(4)
Ending balance, September 30, 2024			$3						$3,052						$3,927						($1)						($13)												$6,968

Alliant Energy																					Accumulated						Shares in
									Additional												Other						Deferred												Total
			Common						Paid-In						Retained						Comprehensive						Compensation												Common
			Stock						Capital						Earnings						Income (Loss)						Trust												Equity
Nine Months Ended September 30, 2025
Beginning balance, December 31, 2024			$3						$3,060						$3,954						$1						($14)												$7,004
Net income attributable to Alliant Energy common shareowners															668																								668
Common stock dividends ($1.5225 per share)															(391)																								(391)
Shareowner Direct Plan issuances									18																														18
Equity-based compensation plans and other									9																														9
Other comprehensive loss, net of tax																					(1)																		(1)
Ending balance, September 30, 2025			$3						$3,087						$4,231						$—						($14)												$7,307
Nine Months Ended September 30, 2024
Beginning balance, December 31, 2023			$3						$3,030						$3,756						$1						($13)												$6,777
Net income attributable to Alliant Energy common shareowners															540																								540
Common stock dividends ($1.44 per share)															(369)																								(369)
Shareowner Direct Plan issuances									18																														18
Equity-based compensation plans and other									4																														4
Other comprehensive loss, net of tax																					(2)																		(2)
Ending balance, September 30, 2024			$3						$3,052						$3,927						($1)						($13)												$6,968

IPL									Additional																		Total
			Common						Paid-In						Retained												Common
			Stock						Capital						Earnings												Equity
Three Months Ended September 30, 2025
Beginning balance, June 30, 2025			$33						$3,357						$1,245												$4,635
Net income															165												165
Common stock dividends															(90)												(90)
Capital contributions from parent									140																		140
Ending balance, September 30, 2025			$33						$3,497						$1,320												$4,850
Three Months Ended September 30, 2024
Beginning balance, June 30, 2024			$33						$3,012						$1,035												$4,080
Net income															190												190
Common stock dividends															(50)												(50)
Capital contributions from parent									200																		200
Ending balance, September 30, 2024			$33						$3,212						$1,175												$4,420

IPL									Additional																		Total
			Common						Paid-In						Retained												Common
			Stock						Capital						Earnings												Equity
Nine Months Ended September 30, 2025
Beginning balance, December 31, 2024			$33						$3,212						$1,216												$4,461
Net income															374												374
Common stock dividends															(270)												(270)
Capital contributions from parent									285																		285
Ending balance, September 30, 2025			$33						$3,497						$1,320												$4,850
Nine Months Ended September 30, 2024
Beginning balance, December 31, 2023			$33						$2,887						$1,054												$3,974
Net income															272												272
Common stock dividends															(151)												(151)
Capital contributions from parent									325																		325
Ending balance, September 30, 2024			$33						$3,212						$1,175												$4,420

WPL									Additional																		Total
			Common						Paid-In						Retained												Common
			Stock						Capital						Earnings												Equity
Three Months Ended September 30, 2025
Beginning balance, June 30, 2025			$66						$2,533						$1,581												$4,180
Net income															123												123
Common stock dividends															(44)												(44)
Capital contributions from parent									80																		80
Ending balance, September 30, 2025			$66						$2,613						$1,660												$4,339
Three Months Ended September 30, 2024
Beginning balance, June 30, 2024			$66						$2,533						$1,411												$4,010
Net income															114												114
Common stock dividends															(49)												(49)
Ending balance, September 30, 2024			$66						$2,533						$1,476												$4,075

WPL									Additional																		Total
			Common						Paid-In						Retained												Common
			Stock						Capital						Earnings												Equity
Nine Months Ended September 30, 2025
Beginning balance, December 31, 2024			$66						$2,533						$1,502												$4,101
Net income															321												321
Common stock dividends															(163)												(163)
Capital contributions from parent									80																		80
Ending balance, September 30, 2025			$66						$2,613						$1,660												$4,339
Nine Months Ended September 30, 2024
Beginning balance, December 31, 2023			$66						$2,478						$1,353												$3,897
Net income															270												270
Common stock dividends															(147)												(147)
Capital contributions from parent									55																		55
Ending balance, September 30, 2024			$66						$2,533						$1,476												$4,075

X

- Definition

Tabular disclosure of an entity's capital units or capital shares, including the value of capital units or capital shares, units authorized, units outstanding and other information necessary to a fair presentation.

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Tabular disclosure of changes in the separate accounts comprising stockholders' equity (in addition to retained earnings) and of the changes in the number of shares of equity securities during at least the most recent annual fiscal period and any subsequent interim period presented is required to make the financial statements sufficiently informative if both financial position and results of operations are presented.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-SubTopic 10
-Topic 505
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-2

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