10-Q – 2025-08-08 – lnt-20250630.htm

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Table of Contents                              

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549

FORM 10-Q

☒      QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
For the quarterly period ended June 30, 2025

or

☐      TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
For the transition period from                    to                    

Name of Registrant, State of Incorporation, Address of Principal Executive Offices, Telephone Number, Commission File Number, IRS Employer Identification Number

ALLIANT ENERGY CORP ORATION
(a Wisconsin Corporation)
4902 N. Biltmore Lane
Madison , Wisconsin 53718
Telephone ( 608 ) 458-3311
Commission File Number - 1-9894
IRS Employer Identification Number - 39-1380265

INTERSTATE POWER & LIGHT CO MPANY
(an Iowa corporation)
Alliant Energy Tower
Cedar Rapids , Iowa 52401
Telephone ( 319 ) 786-4411
Commission File Number - 1-4117
IRS Employer Identification Number - 42-0331370

WISCONSIN POWER & LIGHT CO MPANY
(a Wisconsin corporation)
4902 N. Biltmore Lane
Madison , Wisconsin 53718
Telephone ( 608 ) 458-3311
Commission File Number - 0-337
IRS Employer Identification Number - 39-0714890
This combined Form 10-Q is separately filed by Alliant Energy Corporation, Interstate Power and Light Company and Wisconsin Power and Light Company. Information contained in the Form 10-Q relating to Interstate Power and Light Company and Wisconsin Power and Light Company is filed by each such registrant on its own behalf. Each of Interstate Power and Light Company and Wisconsin Power and Light Company makes no representation as to information relating to registrants other than itself.

Securities registered pursuant to Section 12(b) of the Act:
Alliant Energy Corporation, Common Stock, $0.01 Par Value , Trading Symbol LNT , Nasdaq Global Select Market

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.
Alliant Energy Corporation - Yes ☒ No ☐
Interstate Power and Light Company - Yes ☒ No ☐
Wisconsin Power and Light Company - Yes ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).
Alliant Energy Corporation - Yes ☒ No ☐
Interstate Power and Light Company - Yes ☒ No ☐
Wisconsin Power and Light Company - Yes ☒ No ☐
Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.
Alliant Energy Corporation - Large Accelerated Filer ☒ Accelerated Filer ☐ Non-accelerated Filer ☐ Smaller Reporting Company ☐ Emerging Growth Company ☐
Interstate Power and Light Company - Large Accelerated Filer ☐ Accelerated Filer ☐ Non-accelerated Filer ☒ Smaller Reporting Company ☐ Emerging Growth Company ☐
Wisconsin Power and Light Company - Large Accelerated Filer ☐ Accelerated Filer ☐ Non-accelerated Filer ☒ Smaller Reporting Company ☐ Emerging Growth Company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.
Alliant Energy Corporation ☐
Interstate Power and Light Company ☐
Wisconsin Power and Light Company ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).
Alliant Energy Corporation - Yes ☐ No ☒
Interstate Power and Light Company - Yes ☐ No ☒
Wisconsin Power and Light Company - Yes ☐ No ☒
Number of shares outstanding of each class of common stock as of June 30, 2025:
Alliant Energy Corporation, Common Stock, $0.01 par value, 256,969,227 shares outstanding
Interstate Power and Light Company, Common Stock, $2.50 par value, 13,370,788 shares outstanding (all outstanding shares are owned beneficially and of record by Alliant Energy Corporation)
Wisconsin Power and Light Company, Common Stock, $5 par value, 13,236,601 shares outstanding (all outstanding shares are owned beneficially and of record by Alliant Energy Corporation)

Table of Contents                              

TABLE OF CONTENTS

Page
Definitions

Forward-looking Statements
1

Part I. Financial Information
3

Item 1. Condensed Consolidated Financial Statements (Unaudited)
3

Alliant Energy Corporation
3

Interstate Power and Light Company
6

Wisconsin Power and Light Company
9

Combined Notes to Condensed Consolidated Financial Statements
12

1. Summary of Significant Accounting Policies
12

2. Regulatory Matters
12

3 . Receivables
13

4 . Investments
13

5 . Common Equity
14

6 . Debt
16

7 . Revenues
18

8 . Income Taxes
19

9 . Benefit Plans
19

1 0 . Derivative Instruments
20

1 1 . Fair Value Measurements
21

1 2 . Commitments and Contingencies
23

1 3 . Segments of Business
25

1 4 . Related Parties
27

Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations
28

Item 3. Quantitative and Qualitative Disclosures About Market Risk
36

Item 4. Controls and Procedures
36

Part II. Other Information
37

Item 1. Legal Proceedings
37

Item 1A. Risk Factors
37

Item 2. Unregistered Sales of Equity Securities and Use of Proceeds
37

Item 5. Other Information
37

Item 6. Exhibits
38

Signatures
38

DEFINITIONS
The following abbreviations or acronyms used in this report are defined below:

Abbreviation or Acronym Definition Abbreviation or Acronym Definition
2024 Form 10-K
Combined Annual Report on Form 10-K filed by Alliant Energy, IPL and WPL for the year ended Dec. 31, 2024
IPL Interstate Power and Light Company
AEF Alliant Energy Finance, LLC IUC Iowa Utilities Commission
Alliant Energy Alliant Energy Corporation MDA Management’s Discussion and Analysis of Financial Condition and Results of Operations
ATC American Transmission Company LLC MISO Midcontinent Independent System Operator, Inc.
ATC Holdings Interest in American Transmission Company LLC and ATC Holdco LLC MW Megawatt
Corporate Services Alliant Energy Corporate Services, Inc. MWh Megawatt-hour
Dth Dekatherm N/A Not applicable
EGU Electric generating unit Note(s) Combined Notes to Condensed Consolidated Financial Statements
EPA U.S. Environmental Protection Agency OPEB Other postretirement benefits
EPS Earnings per weighted average common share PSCW Public Service Commission of Wisconsin
Financial Statements Condensed Consolidated Financial Statements U.S. United States of America
FTR Financial transmission right West Riverside West Riverside Energy Center and Solar Facility
GAAP U.S. generally accepted accounting principles WPL Wisconsin Power and Light Company

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FORWARD-LOOKING STATEMENTS
Statements contained in this report that are not of historical fact are forward-looking statements intended to qualify for the safe harbors from liability established by the Private Securities Litigation Reform Act of 1995. These forward-looking statements can be identified as such because the statements include words such as “may,” “believe,” “expect,” “anticipate,” “plan,” “project,” “will,” “projections,” “estimate,” or other words of similar import. Similarly, statements that describe future financial performance or plans or strategies are forward-looking statements. Such forward-looking statements are subject to certain risks and uncertainties that could cause actual results to differ materially from those expressed in, or implied by, such statements. Some, but not all, of the risks and uncertainties of Alliant Energy, IPL and WPL that could materially affect actual results include:
• IPL’s and WPL’s ability to obtain adequate and timely rate relief to allow for, among other things, the recovery of and/or the return on costs, including fuel costs, operating costs, transmission costs, capacity costs, costs of generation projects including such costs that are incurred prior to regulatory approval or exceed initial estimates, deferred expenditures, deferred tax assets, tax expense, interest expense, capital expenditures, marginal costs to service new customers, and remaining costs related to EGUs that have been or may be permanently closed and certain other retired assets, environmental remediation costs, and decreases in sales volumes, as well as earning their authorized rates of return, payments to their parent of expected levels of dividends, the impact of rate design on current and potential customers and demand for energy in their service territories, and the ability to obtain regulatory approval with acceptable conditions for individual customer rates for large load growth customers;
• the impact of IPL’s retail electric base rate moratorium;
• the ability to complete construction of generation and energy storage projects by planned in-service dates and within the cost targets set by regulators due to cost increases of and access to materials, equipment and commodities, which could result from tariffs, duties or other assessments, inflation, labor issues or supply shortages, the ability to successfully resolve warranty issues or contract disputes and the ability to obtain adequate generator interconnection agreements to connect the new projects to MISO in a timely manner;
• weather effects on utility sales volumes and operations;
• the direct or indirect effects resulting from cybersecurity incidents or attacks on Alliant Energy, IPL, WPL, or their suppliers, contractors and partners, or responses to such incidents;
• the impact of customer- and third party-owned generation, including alternative electric suppliers, in IPL’s and WPL’s service territories on system reliability, operating expenses and customers’ demand for electricity;
• economic conditions and the impact of business or facility closures in IPL’s and WPL’s service territories;
• the ability and cost to provide sufficient generation and the ability of ITC Midwest LLC and ATC to provide sufficient transmission capacity for potential load growth, including significant new commercial or industrial customers, such as data centers;
• the ability of potential large load growth customers to timely construct new facilities, as well as the resulting higher system load demand by expected levels and timeframes;
• the impact of energy efficiency, franchise retention and customer disconnects on sales volumes and operating income;
• the impact that price changes may have on IPL’s and WPL’s customers’ demand for electric and gas services and their ability to pay their bills;
• changes in the price of delivered natural gas, transmission, purchased electric energy, purchased electric capacity and delivered coal, particularly during elevated market prices, and any resulting changes to counterparty credit risk, due to shifts in supply and demand caused by market conditions, regulations and MISO’s seasonal resource adequacy process;
• the ability to obtain regulatory approval for constr uction projects with acceptable conditions;
• the ability to achieve the expected level of tax benefits for renewable generation and energy storage projects based on tax guidelines, timely beginning of construction and in-service dates, sourcing permissible amounts of construction support from entities with ties to certain foreign countries, compliance with prevailing wage and apprenticeship requirements, project costs and the level of electricity output generated by qualifying generating facilities, and the ability to efficiently utilize the renewable generation and energy storage project tax benefits to achieve IPL’ s authorized rate of return and for the benefit of IPL’s and WPL’s customers;
• federal and state regulatory or governmental actions, including the impact of legislation, Treasury regulations, executive orders, interpretations and guidance, and changes in public policy, including changes impacting renewable tax credits;
• the ability to utilize tax credits generated to date, and those that may be generated in the future, before they expire, as well as the ability to transfer tax credits that may be generated in the future at adequate pricing;
• the impacts of changes in the tax code, including tax rates, minimum tax rates, adjustments made to deferred tax assets and liabilities, and changes impacting the availability of and ability to transfer renewable tax credits, including preserving the qualification of any future tax credits;
• disruptions to ongoing operations and the supply of materials, services, equipment and commodities needed to continue to operate and maintain existing assets and to construct capital projects, which may result from geopolitical issues, tariffs, supplier manufacturing constraints, regulatory requirements, labor issues or transportation issues, and thus affect the ability to meet capacity requirements and result in increased capacity expense;
• inflation and higher interest rates;
• continued access to the capital markets on competitive terms and rates, and the actions of credit rating agencies;
• the future development of technologies related to electrification, and the ability to reliably store and manage electricity;
• employee workforce factors, including the ability to hire and retain employees with specialized skills, impacts from employee retirements, changes in key executives, ability to create desired corporate culture, collective bargaining agreements and negotiations, work stoppages or restructurings;
• disruptions in the supply and delivery of natural gas, purchased electricity and coal;

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• changes to the creditworthiness of, or performance of obligations by, counterparties with which Alliant Energy, IPL and WPL have contractual arrangements, including large load growth customers, participants in the energy markets and fuel suppliers and transporters;
• the impact of penalties or third-party claims related to, or in connection with, a failure to maintain the security of personally identifiable information, including associated costs to notify affected persons and to mitigate their information security concerns;
• impacts that terrorist attacks may have on Alliant Energy’s, IPL’s and WPL’s operations and recovery of costs associated with restoration activities, or on the operations of Alliant Energy’s investments;
• changes to MISO’s resource adequacy process establishing capacity planning reserve margin and capacity accreditation requirements that may impact how and when new and existing generating facilities, including IPL’s and WPL’s additional solar generation, may be accredited with energy capacity, and may require IPL and WPL to adjust their current resource plans, to add resources to meet the requirements of MISO’s process, or procure capacity in the market whereby such costs might not be recovered in rates;
• any material post-closing payments related to any past asset divestitures, including the transfer of renewable tax credits, which could result from, among other things, indemnification agreements, warranties, guarantees or litigation;
• issues associated with environmental remediation and environmental compliance, including compliance with all current environmental and emissions laws, regulations and permits and future changes in environmental laws and regulations, including the Coal Combustion Residuals Rule, Cross-State Air Pollution Rule and federal, state or local regulations for emissions reductions, including greenhouse gases (GHG), from new and existing fossil-fueled EGUs under the Clean Air Act, and litigation associated with environmental requirements;
• increased pressure from customers, investors and other stakeholders to more rapidly reduce GHG emissions;
• the timely development of technologies, innovations and advancements to provide cost effective alternatives to traditional energy sources;
• the ability to defend against environmental claims brought by state and federal agencies, such as the EPA and state natural resources agencies, or third parties, such as the Sierra Club, and the impact on operating expenses of defending and resolving such claims;
• the direct or indirect effects resulting from breakdown or failure of equipment in the operation of electric and gas distribution systems, such as mechanical problems, disruptions in telecommunications, technological problems, and explosions or fires, and compliance with electric and gas transmission and distribution safety regulations, including regulations promulgated by the Pipeline and Hazardous Materials Safety Administration;
• issues related to the availability and operations of EGUs and energy storage facilities, including start-up risks, breakdown or failure of equipment, fires, availability of warranty coverage and successful resolution of warranty issues or contract disputes for equipment breakdowns or failures, performance below expected or contracted levels of output or efficiency, operator error, employee safety, transmission constraints, compliance with mandatory reliability standards and risks related to recovery of resulting incremental operating, capacity, fuel-related and capital costs through rates;
• impacts that excessive heat, excessive cold, storms, wildfires, or natural disasters may have on Alliant Energy’s, IPL’s and WPL’s operations and construction activities, and recovery of costs associated with restoration activities, or on the operations of Alliant Energy’s investments;
• Alliant Energy’s ability to sustain its dividend payout ratio goal;
• changes to costs of providing benefits and related funding requirements of pension and OPEB plans due to the market value of the assets that fund the plans, economic conditions, financial market performance, interest rates, timing and form of benefits payments, life expectancies and demographics;
• material changes in employee-related benefit and compensation costs, including settlement losses related to pension plans;
• risks associated with operation and ownership of non-utility holdings;
• changes in technology that alter the channels through which customers buy or utilize Alliant Energy’s, IPL’s or WPL’s products and services;
• impacts on equity income from unconsolidated investments from changes in valuations of the assets held, as well as potential changes to ATC’s authorized return on equity;
• impacts of IPL’s future tax benefits from Iowa rate-making practices, including deductions for repairs expenditures and cost of removal obligations, allocation of mixed service costs and state depreciation, and recoverability of the associated regulatory assets from customers, when the differences reverse in future periods;
• current or future litigation, regulatory investigations, proceedings or inquiries;
• reputational damage from negative publicity, protests, fines, penalties and other negative consequences resulting in regulatory and/or legal actions;
• the direct or indirect effects resulting from pandemics;
• the effect of accounting standards issued periodically by standard-setting bodies;
• the ability to successfully complete tax audits and changes in tax accounting methods with no material impact on earnings and cash flows; and
• other factors listed in MDA and Risk Factors in Item 1A in the 2024 Form 10-K .
Alliant Energy, IPL and WPL each assume no obligation, and disclaim any duty, to update the forward-looking statements in this report, except as required by law.
Available Information. Alliant Energy routinely posts important information on its website and considers the Investors section of its website, www.alliantenergy.com/investors , a channel of distribution for material information. Information contained on Alliant Energy’s website is not incorporated herein by reference.

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PART I. FINANCIAL INFORMATION

ITEM 1. CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)

ALLIANT ENERGY CORPORATION

CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED)

For the Three Months For the Six Months
Ended June 30, Ended June 30,
2025 2024 2025 2024
(in millions, except per share amounts)
Revenues:
Electric utility $ 851 $ 789 $ 1,703 $ 1,580
Gas utility 76 69 316 273
Other utility 11 10 25 24
Non-utility 23 26 44 48
Total revenues 961 894 2,088 1,925
Operating expenses:
Electric production fuel and purchased power 150 138 325 301
Electric transmission service 151 147 308 300
Cost of gas sold 30 25 167 139
Other operation and maintenance:
Asset valuation charge for IPL’s Lansing Generating Station — 60 — 60
Other 168 177 327 336
Depreciation and amortization 208 188 420 376
Taxes other than income taxes 31 29 62 61
Total operating expenses 738 764 1,609 1,573
Operating income 223 130 479 352
Other (income) and deductions:
Interest expense 124 108 243 215
Equity income from unconsolidated investments, net ( 10 ) ( 15 ) ( 23 ) ( 31 )
Allowance for funds used during construction ( 23 ) ( 19 ) ( 41 ) ( 38 )
Other 1 2 4 4
Total other (income) and deductions 92 76 183 150
Income before income taxes 131 54 296 202
Income tax benefit ( 43 ) ( 33 ) ( 91 ) ( 43 )

Net income attributable to Alliant Energy common shareowners $ 174 $ 87 $ 387 $ 245
Weighted average number of common shares outstanding:
Basic 256.9 256.4 256.8 256.3
Diluted 257.3 256.7 257.3 256.6
Earnings per weighted average common share attributable to Alliant Energy common shareowners:

Basic $ 0.68 $ 0.34 $ 1.51 $ 0.96
Diluted $ 0.68 $ 0.34 $ 1.50 $ 0.95

Refer to accompanying Combined Notes to Condensed Consolidated Financial Statements.

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ALLIANT ENERGY CORPORATION
CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED)

June 30,
2025 December 31,
2024
(in millions, except per
share and share amounts)
ASSETS
Current assets:
Cash and cash equivalents $ 329 $ 81
Accounts receivable, less allowance for expected credit losses 518 427

Production fuel, at weighted average cost 52 54
Gas stored underground, at weighted average cost 31 55
Materials and supplies, at weighted average cost 195 186
Regulatory assets 164 210

Other 185 171
Total current assets 1,474 1,184
Property, plant and equipment, net 19,376 18,701
Investments:
ATC Holdings 440 415
Other 226 224
Total investments 666 639
Other assets:
Regulatory assets 2,123 2,064
Deferred charges and other 111 126
Total other assets 2,234 2,190
Total assets $ 23,750 $ 22,714

LIABILITIES AND EQUITY
Current liabilities:
Current maturities of long-term debt $ 1,373 $ 1,171
Commercial paper 292 558

Accounts payable 497 532

Regulatory liabilities 71 69
Other 346 385
Total current liabilities 2,579 2,715
Long-term debt, net (excluding current portion) 9,642 8,677
Other liabilities:
Deferred tax liabilities 2,198 2,188
Regulatory liabilities 1,017 959
Pension and other benefit obligations 202 224
Other 967 947
Total other liabilities 4,384 4,318
Commitments and contingencies ( Note 12 )

Equity:
Alliant Energy Corporation common equity:
Common stock - $ 0.01 par value - 480,000,000 shares authorized; 256,969,227 and 256,690,222 shares outstanding
3 3
Additional paid-in capital 3,075 3,060
Retained earnings 4,080 3,954
Accumulated other comprehensive income — 1
Shares in deferred compensation trust - 356,799 and 372,116 shares at a weighted average cost of $ 37.77 and $ 36.56 per share
( 13 ) ( 14 )
Total Alliant Energy Corporation common equity 7,145 7,004

Total liabilities and equity $ 23,750 $ 22,714

Refer to accompanying Combined Notes to Condensed Consolidated Financial Statements.

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ALLIANT ENERGY CORPORATION
CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED)

For the Six Months
Ended June 30,
2025 2024
(in millions)
Cash flows from operating activities:
Net income $ 387 $ 245
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization
420 376
Deferred tax benefit and tax credits ( 100 ) ( 47 )

Asset valuation charge for IPL’s Lansing Generating Station — 60
Other ( 1 ) ( 4 )
Other changes in assets and liabilities:
Accounts receivable ( 289 ) ( 242 )

Accounts payable ( 12 ) 75

Regulatory liabilities 71 ( 12 )
Deferred income taxes (a) 86 86

Other ( 70 ) 25
Net cash flows from operating activities 492 562
Cash flows used for investing activities:
Construction and acquisition expenditures:
Utility business ( 976 ) ( 870 )
Other ( 89 ) ( 90 )
Cash receipts on sold receivables 198 306
Proceeds from sales of partial ownership interests in West Riverside — 123
Other ( 27 ) ( 2 )
Net cash flows used for investing activities ( 894 ) ( 533 )
Cash flows from financing activities:
Common stock dividends ( 261 ) ( 246 )

Proceeds from issuance of long-term debt 1,162 969
Payments to retire long-term debt — ( 305 )
Net change in commercial paper ( 266 ) ( 423 )

Other 15 6
Net cash flows from financing activities 650 1
Net increase in cash, cash equivalents and restricted cash 248 30
Cash, cash equivalents and restricted cash at beginning of period 81 63
Cash, cash equivalents and restricted cash at end of period $ 329 $ 93
Supplemental cash flows information:
Cash (paid) received during the period for:
Interest ($ 239 ) ($ 207 )
Income taxes, net (a) $ 91 $ 89
Significant non-cash investing and financing activities:
Accrued capital expenditures $ 204 $ 272
Beneficial interest obtained in exchange for securitized accounts receivable $ 235 $ 171

(a) 2025 and 2024 include $ 97 million and $ 99 million, respectively, of proceeds from renewable tax credits transferred to other corporate taxpayers.

Refer to accompanying Combined Notes to Condensed Consolidated Financial Statements.

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INTERSTATE POWER AND LIGHT COMPANY

CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED)

For the Three Months For the Six Months
Ended June 30, Ended June 30,
2025 2024 2025 2024
(in millions)
Revenues:
Electric utility $ 418 $ 404 $ 848 $ 795
Gas utility 40 40 158 148
Steam and other 11 9 24 23
Total revenues 469 453 1,030 966
Operating expenses:
Electric production fuel and purchased power 40 48 107 116
Electric transmission service 100 99 207 202
Cost of gas sold 17 17 81 77
Other operation and maintenance:
Asset valuation charge for IPL’s Lansing Generating Station — 60 — 60
Other 84 102 169 187
Depreciation and amortization 115 97 230 193
Taxes other than income taxes 15 14 29 30
Total operating expenses 371 437 823 865
Operating income 98 16 207 101
Other (income) and deductions:
Interest expense 52 42 99 84
Allowance for funds used during construction ( 13 ) ( 11 ) ( 22 ) ( 21 )
Other ( 2 ) — ( 2 ) —
Total other (income) and deductions 37 31 75 63
Income (loss) before income taxes 61 ( 15 ) 132 38
Income tax benefit ( 37 ) ( 33 ) ( 77 ) ( 43 )

Net income $ 98 $ 18 $ 209 $ 81

Earnings per share data is not disclosed given Alliant Energy Corporation is the sole shareowner of all shares of IPL’s common stock outstanding during the periods presented.
Refer to accompanying Combined Notes to Condensed Consolidated Financial Statements.

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INTERSTATE POWER AND LIGHT COMPANY
CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED)

June 30,
2025 December 31,
2024
(in millions, except per
share and share amounts)
ASSETS
Current assets:
Cash and cash equivalents $ 204 $ 29
Accounts receivable, less allowance for expected credit losses 270 192

Production fuel, at weighted average cost 24 30
Gas stored underground, at weighted average cost 11 25
Materials and supplies, at weighted average cost 117 113
Regulatory assets 82 77
Other 72 43
Total current assets 780 509
Property, plant and equipment, net 9,821 9,336
Other assets:
Regulatory assets 1,533 1,509
Deferred charges and other 46 53
Total other assets 1,579 1,562
Total assets $ 12,180 $ 11,407

LIABILITIES AND EQUITY
Current liabilities:
Current maturities of long-term debt $ 300 $ 300
Commercial paper — 50
Accounts payable 290 263
Accounts payable to associated companies 48 47
Accrued taxes 54 77
Accrued interest 50 48
Regulatory liabilities 47 54
Other 77 89
Total current liabilities 866 928
Long-term debt, net (excluding current portion) 4,384 3,790
Other liabilities:
Deferred tax liabilities 1,230 1,179
Regulatory liabilities 496 492
Pension and other benefit obligations 43 46
Other 526 511
Total other liabilities 2,295 2,228
Commitments and contingencies ( Note 12 )

Equity:
Interstate Power and Light Company common equity:
Common stock - $ 2.50 par value - 24,000,000 shares authorized; 13,370,788 shares outstanding
33 33
Additional paid-in capital 3,357 3,212
Retained earnings 1,245 1,216
Total Interstate Power and Light Company common equity 4,635 4,461

Total liabilities and equity $ 12,180 $ 11,407

Refer to accompanying Combined Notes to Condensed Consolidated Financial Statements.

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INTERSTATE POWER AND LIGHT COMPANY
CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED)

For the Six Months
Ended June 30,
2025 2024
(in millions)
Cash flows from operating activities:
Net income $ 209 $ 81
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization 230 193

Deferred tax benefit and tax credits ( 59 ) ( 35 )
Asset valuation charge for IPL’s Lansing Generating Station — 60
Other ( 14 ) 7
Other changes in assets and liabilities:
Accounts receivable ( 273 ) ( 251 )

Regulatory assets ( 47 ) ( 1 )

Deferred income taxes (a) 98 92

Other ( 36 ) 1
Net cash flows from operating activities 108 147
Cash flows used for investing activities:
Construction and acquisition expenditures ( 628 ) ( 500 )
Cash receipts on sold receivables 198 306
Other ( 11 ) ( 15 )
Net cash flows used for investing activities ( 441 ) ( 209 )
Cash flows from financing activities:
Common stock dividends ( 180 ) ( 100 )
Capital contributions from parent 145 125
Proceeds from issuance of long-term debt 594 —

Net change in commercial paper ( 50 ) —
Other ( 1 ) ( 7 )
Net cash flows from financing activities 508 18
Net increase (decrease) in cash, cash equivalents and restricted cash 175 ( 44 )
Cash, cash equivalents and restricted cash at beginning of period 29 53
Cash, cash equivalents and restricted cash at end of period $ 204 $ 9
Supplemental cash flows information:
Cash (paid) received during the period for:
Interest ($ 97 ) ($ 85 )
Income taxes, net (a) $ 68 $ 92
Significant non-cash investing and financing activities:
Accrued capital expenditures $ 149 $ 119
Beneficial interest obtained in exchange for securitized accounts receivable $ 235 $ 171

(a) 2025 and 2024 include $ 73 million and $ 71 million, respectively, of proceeds from renewable tax credits transferred to other corporate taxpayers.

Refer to accompanying Combined Notes to Condensed Consolidated Financial Statements.

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WISCONSIN POWER AND LIGHT COMPANY

CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED)

For the Three Months For the Six Months
Ended June 30, Ended June 30,
2025 2024 2025 2024
(in millions)
Revenues:
Electric utility $ 433 $ 385 $ 855 $ 785
Gas utility 36 29 158 125
Other — 1 1 1
Total revenues 469 415 1,014 911
Operating expenses:
Electric production fuel and purchased power 110 90 218 186
Electric transmission service 51 49 101 98
Cost of gas sold 13 8 86 62
Other operation and maintenance 72 67 137 128
Depreciation and amortization 90 87 183 178
Taxes other than income taxes 15 14 29 28
Total operating expenses 351 315 754 680
Operating income 118 100 260 231
Other (income) and deductions:
Interest expense 43 41 86 82

Allowance for funds used during construction ( 10 ) ( 8 ) ( 19 ) ( 17 )
Other 3 — 5 2
Total other (income) and deductions 36 33 72 67
Income before income taxes 82 67 188 164
Income tax expense (benefit) ( 5 ) 3 ( 10 ) 8
Net income $ 87 $ 64 $ 198 $ 156

Earnings per share data is not disclosed given Alliant Energy Corporation is the sole shareowner of all shares of WPL’s common stock outstanding during the periods presented.
Refer to accompanying Combined Notes to Condensed Consolidated Financial Statements.

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WISCONSIN POWER AND LIGHT COMPANY
CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED)

June 30,
2025 December 31,
2024
(in millions, except per
share and share amounts)
ASSETS
Current assets:
Cash and cash equivalents $ 10 $ 51
Accounts receivable, less allowance for expected credit losses 234 220
Production fuel, at weighted average cost 28 24
Gas stored underground, at weighted average cost 20 30
Materials and supplies, at weighted average cost 71 69
Regulatory assets 82 133
Prepaid gross receipts tax 49 51
Other 68 57
Total current assets 562 635
Property, plant and equipment, net 9,032 8,861
Other assets:
Regulatory assets 590 555
Deferred charges and other 52 55
Total other assets 642 610
Total assets $ 10,236 $ 10,106

LIABILITIES AND EQUITY
Current liabilities:

Commercial paper $ 292 $ 183

Accounts payable 158 209

Accrued interest 45 44
Regulatory liabilities 24 15
Other 81 94
Total current liabilities 600 545
Long-term debt, net 3,371 3,370
Other liabilities:
Deferred tax liabilities
818 865
Regulatory liabilities 521 467

Pension and other benefit obligations 88 102
Other 658 656
Total other liabilities 2,085 2,090
Commitments and contingencies ( Note 12 )

Equity:
Wisconsin Power and Light Company common equity:
Common stock - $ 5 par value - 18,000,000 shares authorized; 13,236,601 shares outstanding
66 66
Additional paid-in capital 2,533 2,533
Retained earnings 1,581 1,502
Total Wisconsin Power and Light Company common equity 4,180 4,101

Total liabilities and equity $ 10,236 $ 10,106

Refer to accompanying Combined Notes to Condensed Consolidated Financial Statements.

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WISCONSIN POWER AND LIGHT COMPANY
CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED)

For the Six Months
Ended June 30,
2025 2024
(in millions)
Cash flows from operating activities:
Net income $ 198 $ 156
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization 183 178

Deferred tax benefit and tax credits ( 43 ) ( 20 )
Other ( 4 ) ( 4 )
Other changes in assets and liabilities:
Accounts receivable ( 33 ) 10

Regulatory assets 18 44
Accounts payable ( 9 ) 41

Regulatory liabilities 65 5

Other ( 38 ) ( 19 )
Net cash flows from operating activities 337 391
Cash flows used for investing activities:
Construction and acquisition expenditures ( 348 ) ( 370 )
Proceeds from sales of partial ownership interests in West Riverside — 123
Other ( 14 ) —
Net cash flows used for investing activities ( 362 ) ( 247 )
Cash flows used for financing activities:
Common stock dividends ( 119 ) ( 98 )
Capital contributions from parent — 55
Proceeds from issuance of long-term debt — 297

Net change in commercial paper 109 ( 318 )

Other ( 6 ) ( 7 )
Net cash flows used for financing activities ( 16 ) ( 71 )
Net increase (decrease) in cash, cash equivalents and restricted cash ( 41 ) 73
Cash, cash equivalents and restricted cash at beginning of period 51 7
Cash, cash equivalents and restricted cash at end of period $ 10 $ 80
Supplemental cash flows information:
Cash (paid) received during the period for:
Interest ($ 88 ) ($ 76 )
Income taxes, net (a) $ 8 ($ 10 )
Significant non-cash investing and financing activities:
Accrued capital expenditures $ 48 $ 146

(a) 2025 and 2024 include $ 24 million and $ 28 million, respectively, of proceeds from renewable tax credits transferred to other corporate taxpayers.

Refer to accompanying Combined Notes to Condensed Consolidated Financial Statements.

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ALLIANT ENERGY CORPORATION
INTERSTATE POWER AND LIGHT COMPANY
WISCONSIN POWER AND LIGHT COMPANY

COMBINED NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)

NOTE 1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
NOTE 1(a) General - The interim unaudited Financial Statements included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (SEC). Accordingly, certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted, although management believes that the disclosures are adequate to make the information presented not misleading. These Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the 2024 Form 10-K .

In the opinion of management, all adjustments, which unless otherwise noted are normal and recurring in nature, necessary for a fair presentation of the results of operations, financial position and cash flows have been made. Results for the six months ended June 30, 2025 are not necessarily indicative of results that may be expected for the year ending December 31, 2025.

A change in management’s estimates or assumptions could have a material impact on financial condition and results of operations during the period in which such change occurred. Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes.

NOTE 1(b) Cash and Cash Equivalents - At June 30, 2025, cash and cash equivalents included money market fund investments and time deposits of $ 303 million and $ 194 million for Alliant Energy and IPL, respectively, with weighted average interest rates of 4 %.

NOTE 1(c) Asset Retirement Obligations (AROs) - In the second quarter of 2024, substantially due to the enactment of the revised Coal Combustion Residuals Rule, Alliant Energy and IPL recorded a pre-tax non-cash charge of $ 20 million to “Other operation and maintenance” in their income statements for the AROs allocated to IPL’s steam business for its Prairie Creek Generating Station and the retired Sixth Street Generating Station as established in prior rate reviews.

NOTE 2. REGULATORY MATTERS
Regulatory Assets and Regulatory Liabilities -
Regulatory assets were comprised of the following items (in millions):

Alliant Energy IPL WPL
June 30,
2025 December 31,
2024 June 30,
2025 December 31,
2024 June 30,
2025 December 31,
2024
Tax-related $ 1,030 $ 989 $ 897 $ 870 $ 133 $ 119
AROs 427 401 296 281 131 120
Pension and OPEB costs 306 315 153 157 153 158
Assets retired early 167 180 157 168 10 12
Derivatives 57 60 14 15 43 45
Non-service pension and OPEB costs 54 51 20 19 34 32
Commodity cost recovery 49 68 10 2 39 66
WPL’s Western Wisconsin gas distribution expansion investments 40 42 — — 40 42

Other 157 168 68 74 89 94
$ 2,287 $ 2,274 $ 1,615 $ 1,586 $ 672 $ 688

Assets retired early - IPL’s retail electric rate review for the October 2024 through September 2025 forward-looking Test Period filed with the IUC in October 2023 included a request for continued recovery of and a return on the remaining net book value of IPL’s Lansing Generating Station through 2037. In June 2024, IPL reached a partial non-unanimous settlement agreement with certain stakeholders, which the IUC subsequently approved in September 2024. The agreement included a return of the remaining net book value of Lansing, but did not include a return on the remaining net book value of Lansing. As a result, the return on the remaining net book value is no longer probable of recovery from IPL’s retail electric customers and in the second quarter of 2024, a pre-tax non-cash charge of $ 60 million was recorded to “Asset valuation charge for IPL’s Lansing Generating Station” in Alliant Energy’s and IPL’s income statements.

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Regulatory liabilities were comprised of the following items (in millions):

Alliant Energy IPL WPL
June 30,
2025 December 31,
2024 June 30,
2025 December 31,
2024 June 30,
2025 December 31,
2024
Tax-related $ 611 $ 582 $ 275 $ 286 $ 336 $ 296
Cost of removal obligations 349 347 206 205 143 142
Derivatives 60 53 32 29 28 24

Other 68 46 30 26 38 20
$ 1,088 $ 1,028 $ 543 $ 546 $ 545 $ 482

Tax-related - The increase in Alliant Energy’s and WPL’s tax-related regulatory liabilities was primarily due to tax benefits resulting from WPL electing investment tax credit treatment for certain energy storage facilities in 2025.

NOTE 3. RECEIVABLES
Sales of Accounts Receivable - IPL maintains a Receivables Purchase and Sale Agreement (Receivables Agreement) whereby it may sell its customer accounts receivables, unbilled revenues and certain other accounts receivables to a third party through wholly-owned and consolidated special purpose entities. The transfers of receivables meet the criteria for sale accounting established by the transfer of financial assets accounting rules. Effective May 2025, the limit on cash proceeds under the Receivables Agreement was changed to $ 5 million. As of June 30, 2025, IPL had $ 4 million of available capacity under its sales of accounts receivable program. IPL’s maximum and average outstanding aggregate cash proceeds (based on daily outstanding balances) related to the sales of accounts receivable program for the three and six months ended June 30 were as follows (in millions):

Three Months Six Months
2025 2024 2025 2024
Maximum outstanding aggregate cash proceeds $ 110 $ 110 $ 110 $ 110
Average outstanding aggregate cash proceeds 60 73 84 48

The attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions):

June 30, 2025 December 31, 2024
Customer accounts receivable $ 135 $ 137
Unbilled utility revenues 114 108

Receivables sold to third party 249 245
Less: cash proceeds 1 70
Deferred proceeds 248 175
Less: allowance for expected credit losses 13 12
Fair value of deferred proceeds $ 235 $ 163

As of June 30, 2025, outstanding receivables past due under the Receivables Agreement were $ 16 million. Additional attributes of IPL’s receivables sold under the Receivables Agreement for the three and six months ended June 30 were as follows (in millions):

Three Months Six Months
2025 2024 2025 2024
Collections $ 445 $ 456 $ 1,052 $ 1,013
Write-offs, net of recoveries 2 2 4 5

NOTE 4. INVESTMENTS
Unconsolidated Equity Investments - Alliant Energy’s equity (income) loss from unconsolidated investments accounted for under the equity method of accounting for the three and six months ended June 30 was as follows (in millions):

Three Months Six Months
2025 2024 2025 2024
ATC Holdings ($ 14 ) ($ 13 ) ($ 28 ) ($ 25 )
Non-utility wind farm in Oklahoma ( 3 ) ( 2 ) ( 4 ) ( 3 )
Corporate venture investments 7 — 11 ( 1 )
Other — — ( 2 ) ( 2 )
($ 10 ) ($ 15 ) ($ 23 ) ($ 31 )

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NOTE 5. COMMON EQUITY
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 192,628  
Equity-based compensation plans 86,377  

Shares outstanding, June 30, 2025
256,969,227  

At-the-Market Offering Program - In May 2025, Alliant Energy filed a prospectus supplement and executed a related distribution agreement, under which it may sell up to $ 1.3 billion in aggregate of its common stock through 2028 through an at-the-market offering program that includes an equity forward sales component. Alliant Energy expects to use proceeds from the issuance of common stock for general corporate purposes.

In the second quarter of 2025, Alliant Energy entered into forward sale agreements under its at-the-market offering program with various counterparties who borrowed and sold an aggregate of 2,913,023 shares of Alliant Energy common stock at an aggregate gross sales price of $ 179 million, including approximately $ 2 million in commissions, to the counterparties payable by Alliant Energy when the forward sale agreements are settled. Alliant Energy has not yet received any proceeds from this program and no amounts have been or will be recorded in equity on Alliant Energy’s balance sheets until the forward sale agreements settle. Alliant Energy expects to settle the forward sale agreements prior to December 31, 2026 through physical delivery of shares of common stock in exchange for cash proceeds at the then-applicable forward sale price; however, Alliant Energy may elect cash settlement or net share settlement for all or a portion of the obligations under the forward sale agreements. As of June 30, 2025, the weighted-average forward price, net of commissions, was $ 60.84 per share and is subject to daily adjustment based on a floating interest rate factor and decreased by other fixed amounts specified in the forward sale agreements. As of June 30, 2025, Alliant Energy could have settled all of its outstanding forward sale agreements under the at-the-market offering program with physical delivery of 2,913,023 shares of Alliant Energy common stock to the counterparties in exchange for cash of $ 177 million.

Alliant Energy has concluded that the forward sale agreements meet the derivative scope exception for certain contracts involving an entity’s own equity. Until settlement of the forward sale agreements, Alliant Energy’s EPS dilution resulting from the agreements, if any, is determined using the treasury stock method. Share dilution occurs when the average market price of Alliant Energy stock during the reporting period is higher than the forward sale price as of the end of the reporting period. As of June 30, 2025, 26,986 incremental shares were included in the calculation of diluted EPS related to the securities under the forward sale agreements.

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 Trust Equity
Three Months Ended June 30, 2025
Beginning balance, March 31, 2025
$ 3 $ 3,066 $ 4,037 $ — ($ 13 ) $ 7,093
Net income attributable to Alliant Energy common shareowners 174 174
Common stock dividends ($ 0.5075 per share)
( 131 ) ( 131 )
Shareowner Direct Plan issuances 6 6
Equity-based compensation plans and other 3 3

Ending balance, June 30, 2025
$ 3 $ 3,075 $ 4,080 $ — ($ 13 ) $ 7,145
Three Months Ended June 30, 2024
Beginning balance, March 31, 2024
$ 3 $ 3,033 $ 3,791 $ 2 ($ 12 ) $ 6,817
Net income attributable to Alliant Energy common shareowners 87 87
Common stock dividends ($ 0.48 per share)
( 123 ) ( 123 )
Shareowner Direct Plan issuances 6 6
Equity-based compensation plans and other 3 3

Other comprehensive income, net of tax 1 1
Ending balance, June 30, 2024
$ 3 $ 3,042 $ 3,755 $ 3 ($ 12 ) $ 6,791

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Alliant Energy Accumulated Shares in
Additional Other Deferred Total
Common Paid-In Retained Comprehensive Compensation Common
Stock Capital Earnings Income (Loss) Trust Equity
Six Months Ended June 30, 2025
Beginning balance, December 31, 2024
$ 3 $ 3,060 $ 3,954 $ 1 ($ 14 ) $ 7,004
Net income attributable to Alliant Energy common shareowners 387 387
Common stock dividends ($ 1.015 per share)
( 261 ) ( 261 )
Shareowner Direct Plan issuances 12 12
Equity-based compensation plans and other 3 1 4

Other comprehensive loss, net of tax ( 1 ) ( 1 )
Ending balance, June 30, 2025
$ 3 $ 3,075 $ 4,080 $ — ($ 13 ) $ 7,145
Six Months Ended June 30, 2024
Beginning balance, December 31, 2023
$ 3 $ 3,030 $ 3,756 $ 1 ($ 13 ) $ 6,777
Net income attributable to Alliant Energy common shareowners 245 245
Common stock dividends ($ 0.96 per share)
( 246 ) ( 246 )
Shareowner Direct Plan issuances 12 12
Equity-based compensation plans and other 1 1

Other comprehensive income, net of tax 2 2
Ending balance, June 30, 2024
$ 3 $ 3,042 $ 3,755 $ 3 ($ 12 ) $ 6,791

IPL Additional Total
Common Paid-In Retained Common
Stock Capital Earnings Equity
Three Months Ended June 30, 2025
Beginning balance, March 31, 2025
$ 33 $ 3,257 $ 1,237 $ 4,527
Net income 98 98
Common stock dividends ( 90 ) ( 90 )
Capital contributions from parent 100 100
Ending balance, June 30, 2025
$ 33 $ 3,357 $ 1,245 $ 4,635
Three Months Ended June 30, 2024
Beginning balance, March 31, 2024
$ 33 $ 2,937 $ 1,067 $ 4,037
Net income 18 18
Common stock dividends ( 50 ) ( 50 )
Capital contributions from parent 75 75
Ending balance, June 30, 2024
$ 33 $ 3,012 $ 1,035 $ 4,080

IPL Additional Total
Common Paid-In Retained Common
Stock Capital Earnings Equity
Six Months Ended June 30, 2025
Beginning balance, December 31, 2024
$ 33 $ 3,212 $ 1,216 $ 4,461
Net income 209 209
Common stock dividends ( 180 ) ( 180 )
Capital contributions from parent 145 145
Ending balance, June 30, 2025
$ 33 $ 3,357 $ 1,245 $ 4,635
Six Months Ended June 30, 2024
Beginning balance, December 31, 2023
$ 33 $ 2,887 $ 1,054 $ 3,974
Net income 81 81
Common stock dividends ( 100 ) ( 100 )
Capital contributions from parent 125 125
Ending balance, June 30, 2024
$ 33 $ 3,012 $ 1,035 $ 4,080

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WPL Additional Total
Common Paid-In Retained Common
Stock Capital Earnings Equity
Three Months Ended June 30, 2025
Beginning balance, March 31, 2025
$ 66 $ 2,533 $ 1,537 $ 4,136
Net income 87 87
Common stock dividends ( 43 ) ( 43 )

Ending balance, June 30, 2025
$ 66 $ 2,533 $ 1,581 $ 4,180
Three Months Ended June 30, 2024
Beginning balance, March 31, 2024
$ 66 $ 2,533 $ 1,396 $ 3,995
Net income 64 64
Common stock dividends ( 49 ) ( 49 )

Ending balance, June 30, 2024
$ 66 $ 2,533 $ 1,411 $ 4,010

WPL Additional Total
Common Paid-In Retained Common
Stock Capital Earnings Equity
Six Months Ended June 30, 2025
Beginning balance, December 31, 2024
$ 66 $ 2,533 $ 1,502 $ 4,101
Net income 198 198
Common stock dividends ( 119 ) ( 119 )

Ending balance, June 30, 2025
$ 66 $ 2,533 $ 1,581 $ 4,180
Six Months Ended June 30, 2024
Beginning balance, December 31, 2023
$ 66 $ 2,478 $ 1,353 $ 3,897
Net income 156 156
Common stock dividends ( 98 ) ( 98 )
Capital contributions from parent 55 55

Ending balance, June 30, 2024
$ 66 $ 2,533 $ 1,411 $ 4,010

NOTE 6. DEBT
NOTE 6(a) Short-term Debt - In March 2025, Alliant Energy, IPL and WPL reallocated credit facility capacity amounts to $ 550 million for Alliant Energy at the parent company level, $ 350 million for IPL and $ 400 million for WPL, within the $ 1.3 billion total commitment. Information regarding commercial paper and borrowings under the single credit facility classified as short-term debt was as follows (dollars in millions):

June 30, 2025 Alliant Energy IPL WPL
Amount outstanding $ 292 $ — $ 292
Weighted average interest rates 4.6 % N/A 4.6 %
Available credit facility capacity $ 1,008 $ 350 $ 108

Alliant Energy IPL WPL
Three Months Ended June 30 2025 2024 2025 2024 2025 2024
Maximum amount outstanding (based on daily outstanding balances) $ 741 $ 435 $ 141 $ 19 $ 292 $ 57
Average amount outstanding (based on daily outstanding balances) $ 449 $ 275 $ 33 $ 2 $ 225 $ 8
Weighted average interest rates 4.6 % 5.5 % 4.6 % 5.5 % 4.6 % 5.4 %
Six Months Ended June 30
Maximum amount outstanding (based on daily outstanding balances) $ 741 $ 632 $ 141 $ 19 $ 292 $ 390
Average amount outstanding (based on daily outstanding balances) $ 495 $ 381 $ 43 $ 1 $ 193 $ 131
Weighted average interest rates 4.6 % 5.5 % 4.6 % 5.5 % 4.6 % 5.5 %

NOTE 6(b) Long-term Debt - In March 2025, AEF entered into a $ 300 million variable rate ( 5 % as of June 30, 2025) term loan credit agreement (with Alliant Energy as guarantor), which expires in March 2026. This term loan credit agreement 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. AEF’s restated term loan credit 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.

In May 2025, IPL issued $ 600 million of 5.6 % senior debentures due 2035. A portion of the net proceeds from this issuance was used for the July 2025 retirement of IPL’s $ 50 million 5.5 % senior debentures and placed in money market fund investments and time deposits pending the August 2025 retirement of IPL’s $ 250 million 3.4 % senior debentures, a portion was used to reduce cash amounts received from its sale of accounts receivable program and commercial paper classified as long-term debt, and the remainder of the net proceeds was used for general corporate purposes.

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Convertible Senior 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.

O n or after March 1, 2028 until the cl ose 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 June 30, 2025, the conditions allowing holders of the 2028 Notes and Alliant Energy’s convertible senior notes due 2026 (the 2026 Notes) to convert their respective notes were not met, and the 2028 Notes were classified as “Long-term debt, net” and the 2026 Notes were classified as “Current maturities of long-term debt,” on Alliant Energy’s balance sheet. As of June 30, 2025, the net carrying amount was $ 568 million and $ 573 million, with unamortized debt issuance costs of $ 7 million and $ 2 million, and the estimated fair value (Level 2) was $ 574 million and $ 592 million for the 2028 Notes and 2026 Notes, respectively. As of June 30, 2025, there were no shares of Alliant Energy’s common stock related to the potential conversion of the 2028 Notes and 2026 Notes included in diluted EPS based on Alliant Energy’s average stock prices and the relevant terms of the respective notes.

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NOTE 7. REVENUES
Disaggregation of revenues from contracts with customers is provided for each reportable segment (IPL and WPL), as well as by customer class within electric and gas sales, as follows (in millions):

Alliant Energy IPL WPL
Three Months Ended June 30 2025 2024 2025 2024 2025 2024
Electric Utility:
Retail - residential $ 295 $ 291 $ 142 $ 151 $ 153 $ 140
Retail - commercial 211 191 135 118 76 73
Retail - industrial 240 237 118 118 122 119
Wholesale 49 43 14 13 35 30
Bulk power and other 56 27 9 4 47 23
Total Electric Utility 851 789 418 404 433 385
Gas Utility:
Retail - residential 41 38 21 22 20 16
Retail - commercial 20 19 10 11 10 8
Retail - industrial 3 2 2 1 1 1
Transportation/other 12 10 7 6 5 4
Total Gas Utility 76 69 40 40 36 29
Other Utility:
Steam 9 9 9 9 — —
Other utility 2 1 2 — — 1
Total Other Utility 11 10 11 9 — 1
Non-Utility and Other:
Travero and other 23 26 — — — —

Total Non-Utility and Other 23 26 — — — —
Total revenues $ 961 $ 894 $ 469 $ 453 $ 469 $ 415

Alliant Energy IPL WPL
Six Months Ended June 30 2025 2024 2025 2024 2025 2024
Electric Utility:
Retail - residential $ 618 $ 588 $ 297 $ 301 $ 321 $ 287
Retail - commercial 425 377 271 232 154 145
Retail - industrial 475 460 236 229 239 231
Wholesale 97 89 28 26 69 63
Bulk power and other 88 66 16 7 72 59
Total Electric Utility 1,703 1,580 848 795 855 785
Gas Utility:
Retail - residential 188 165 95 90 93 75
Retail - commercial 94 80 43 41 51 39
Retail - industrial 8 6 4 4 4 2
Transportation/other 26 22 16 13 10 9
Total Gas Utility 316 273 158 148 158 125
Other Utility:
Steam 19 20 19 20 — —
Other utility 6 4 5 3 1 1
Total Other Utility 25 24 24 23 1 1
Non-Utility and Other:
Travero and other 44 48 — — — —

Total Non-Utility and Other 44 48 — — — —
Total revenues $ 2,088 $ 1,925 $ 1,030 $ 966 $ 1,014 $ 911

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NOTE 8. INCOME TAXES
Income Tax Rates - Overall effective income tax rates for the three and six months ended June 30, which were computed by dividing income tax expense (benefit) by income before income taxes, were as follows. The effective income tax rates were different than the federal statutory rate primarily due to state income taxes, production tax credits, investment tax credits, amortization of excess deferred taxes and the effect of rate-making on property-related differences. Also impacting Alliant Energy’s and IPL’s effective income tax rates for the three and six months ended June 30, 2024 were the pre-tax non-cash charge of $ 60 million for IPL’s Lansing Generating Station discussed in Note 2 and the pre-tax non-cash charge of $ 20 million for the AROs allocated to IPL’s steam business discussed in Note 1(c) . Alliant Energy’s, IPL’s and WPL’s effective income tax rates for the three and six months ended June 30, 2025 were also impacted by additional tax credits in 2025 from renewable generation and energy storage projects placed in service in 2024 and/or expected to be placed in service in 2025.

Alliant Energy IPL WPL
Three Months Six Months Three Months Six Months Three Months Six Months
2025 2024 2025 2024 2025 2024 2025 2024 2025 2024 2025 2024
Overall income tax rate ( 33 %) ( 61 %) ( 31 %) ( 21 %) ( 61 %) 220 % ( 58 %) ( 113 %) ( 6 %) 4 % ( 5 %) 5 %

Deferred Tax Assets and Liabilities -
Carryforwards - At June 30, 2025, the carryforwards and expiration dates were estimated as follows (in millions):

Range of Expiration Dates Alliant Energy IPL WPL

State net operating losses 2025-2045 $ 323 $ 7 $ 1
Federal tax credits 2033-2045 678 437 228

NOTE 9. BENEFIT PLANS
NOTE 9(a) Pension and OPEB Plans -
Net Periodic Benefit Costs - The components of net periodic benefit costs for sponsored defined benefit pension and OPEB plans for the three and six months ended June 30 are included below (in millions). For IPL and WPL, amounts are for their plan participants covered under plans they sponsor, as well as amounts directly assigned to them related to certain participants in the Alliant Energy and Corporate Services sponsored plans.

Defined Benefit Pension Plans OPEB Plans
Three Months Six Months Three Months Six Months
Alliant Energy 2025 2024 2025 2024 2025 2024 2025 2024
Service cost $ 1 $ 1 $ 2 $ 2 $ 1 $ 1 $ 1 $ 1
Interest cost 12 11 23 22 2 2 4 4
Expected return on plan assets ( 14 ) ( 14 ) ( 27 ) ( 27 ) ( 2 ) ( 1 ) ( 3 ) ( 2 )

Amortization of actuarial loss 5 6 11 12 — — — —

$ 4 $ 4 $ 9 $ 9 $ 1 $ 2 $ 2 $ 3

Defined Benefit Pension Plans OPEB Plans
Three Months Six Months Three Months Six Months
IPL 2025 2024 2025 2024 2025 2024 2025 2024
Service cost $ — $ — $ 1 $ 1 $ — $ — $ — $ —
Interest cost 5 5 10 10 1 1 2 2
Expected return on plan assets ( 6 ) ( 6 ) ( 12 ) ( 13 ) ( 1 ) ( 1 ) ( 2 ) ( 2 )

Amortization of actuarial loss 2 3 4 5 — — — —
$ 1 $ 2 $ 3 $ 3 $ — $ — $ — $ —

Defined Benefit Pension Plans OPEB Plans
Three Months Six Months Three Months Six Months
WPL 2025 2024 2025 2024 2025 2024 2025 2024
Service cost $ 1 $ 1 $ 1 $ 1 $ — $ — $ — $ —
Interest cost 5 5 10 10 — 1 1 2
Expected return on plan assets ( 6 ) ( 6 ) ( 12 ) ( 12 ) — — — —

Amortization of actuarial loss 2 3 5 6 — — — —

$ 2 $ 3 $ 4 $ 5 $ — $ 1 $ 1 $ 2

NOTE 9(b) Equity-based Compensation Plans - A summary of compensation expense, including amounts allocated to IPL and WPL, and the related income tax benefits recognized for share-based compensation awards for the three and six months ended June 30 was as follows (in millions):

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Alliant Energy IPL WPL
Three Months Six Months Three Months Six Months Three Months Six Months
2025 2024 2025 2024 2025 2024 2025 2024 2025 2024 2025 2024
Compensation expense $ 3 $ 3 $ 7 $ 7 $ 2 $ 2 $ 4 $ 4 $ 1 $ 1 $ 3 $ 3
Income tax benefits 1 1 2 2 — — 1 1 — — 1 1

As of June 30, 2025, Alliant Energy’s, IPL’s and WPL’s total unrecognized compensation cost related to share-based compensation awards was $ 21 million, $ 10 million and $ 10 million, respectively, which is expected to be recognized over a weighted average period of between 1 year and 2 years.

For the six months ended June 30, 2025, performance shares and restricted stock units were granted to key employees under the equity-based compensation plans as follows. These shares and units will be paid out in shares of common stock, and are therefore accounted for as equity awards.

Weighted Average
Grants Grant Date Fair Value
Performance shares (total shareowner return metric) 105,523 $ 66.51
Performance shares (net income and environmental metrics) 118,457 61.61
Restricted stock units 98,821 61.62

As of June 30, 2025, 397,023 shares were included in the calculation of diluted EPS related to the nonvested equity awards.

NOTE 10. DERIVATIVE INSTRUMENTS
Commodity Derivatives -
Notional Amounts - As of June 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
1,911   2025-2026 24,310   2025-2026 153,204   2025-2032 1,260   2025
IPL 523   2025-2026 9,555   2025-2026 66,568   2025-2030 —   —
WPL 1,388   2025-2026 14,755   2025-2026 86,636   2025-2032 1,260   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
June 30,
2025 December 31,
2024 June 30,
2025 December 31,
2024 June 30,
2025 December 31,
2024
Current derivative assets $ 75 $ 41 $ 53 $ 29 $ 22 $ 12
Non-current derivative assets 30 34 16 19 14 15
Current derivative liabilities 23 26 9 11 14 15
Non-current derivative liabilities 30 32 3 2 27 30

During the six months ended June 30, 2025, Alliant Energy’s, IPL’s and WPL’s derivative assets increased primarily due to new FTRs resulting from the annual FTR auction in the second quarter of 2025 operated by MISO. 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 June 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.

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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
June 30, 2025
Derivative assets $ 105 $ 90 $ 69 $ 61 $ 36 $ 29
Derivative liabilities 53 38 12 4 41 34
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.

NOTE 11. 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 June 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 and time deposits $ 303   $ 303   $ —   $ —   $ 303   $ 52   $ 52   $ —   $ —   $ 52  
Commodity derivatives 105   —   48   57   105   75   —   48   27   75  

Deferred proceeds 235   —   —   235   235   163   —   —   163   163  
Liabilities:
Commodity derivatives 53   —   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  

IPL June 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 and time deposits $ 194   $ 194   $ —   $ —   $ 194   $ 9   $ 9   $ —   $ —   $ 9  
Commodity derivatives 69   —   24   45   69   48   —   26   22   48  
Deferred proceeds 235   —   —   235   235   163   —   —   163   163  
Liabilities:
Commodity derivatives 12   —   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  

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WPL June 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 36   —   24   12   36   27   —   22   5   27  
Liabilities:
Commodity derivatives 41   —   41   —   41   45   —   45   —   45  
Long-term debt 3,371   —   3,238   —   3,238   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 June 30 2025 2024 2025 2024
Beginning balance, April 1 $ 9 $ 7 $ 86 $ 184
Total ne t gains (losses) i ncluded in changes in net assets (realized/unrealized)
10 ( 5 ) — —

Purchases 50 59 — —
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 Energy Commodity Contract Derivative
Assets and (Liabilities), net Deferred Proceeds
Six Months Ended June 30 2025 2024 2025 2024
Beginning balance, January 1 $ 25 $ 24 $ 163 $ 216
Total n et gains (losses) inc luded in changes in net assets (realized/unrealized)
8 ( 8 ) — —

Purchases 50 59 — —
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 ) $ — $ —

IPL Commodity Contract Derivative
Assets and (Liabilities), net Deferred Proceeds
Three Months Ended June 30 2025 2024 2025 2024
Beginning balance, April 1 $ 9 $ 5 $ 86 $ 184
Total net gains (losses) includ ed in changes in net assets (realized/unrealized)
6 ( 2 ) — —

Purchases 40 45 — —
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 ) $ — $ —

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IPL Commodity Contract Derivative
Assets and (Liabilities), net Deferred Proceeds
Six Months Ended June 30 2025 2024 2025 2024
Beginning balance, January 1 $ 20 $ 19 $ 163 $ 216
Total net ga ins (losses) in cluded in changes in net assets (realized/unrealized)
6 ( 6 ) — —

Purchases 40 45 — —
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 ) $ — $ —

WPL Commodity Contract Derivative
Assets and (Liabilities), net
Three Months Ended June 30 2025 2024
Beginning balance, April 1 $ — $ 2
Total ne t gains (losses) includ ed in changes in net assets (realized/unrealized)
4 ( 3 )

Purchases 10 14

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 asset s and liabilities held at June 30
$ 4 ($ 3 )

WPL Commodity Contract Derivative
Assets and (Liabilities), net
Six Months Ended June 30 2025 2024
Beginning balance, January 1 $ 5 $ 5
Total net gains (losses) in cluded in changes in net assets (realized/unrealized)
2 ( 2 )

Purchases 10 14

Settlements ( 5 ) ( 6 )
Ending balance, June 30
$ 12 $ 11
The amou nt 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.

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
June 30, 2025 $ 6 $ 50 $ 6 $ 38 $ — $ 12
December 31, 2024 — 25 — 20 — 5

NOTE 12. COMMITMENTS AND CONTINGENCIES
NOTE 12(a) Capital Purchase Commitments - Various contractual obligations contain minimum future commitments related to capital expenditures for certain construction projects, including improvements at the natural gas-fired Neenah Energy Facility and Sheboygan Falls Energy Facility, and IPL’s and WPL’s expansion of energy storage. At June 30, 2025, Alliant Energy’s, IPL’s and WPL’s minimum future commitments for these projects were $ 287 million, $ 128 million and $ 157 million, respectively.

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NOTE 12(b) Other Purchase Commitments - Various commodity supply, transportation and storage contracts help meet obligations to provide electricity and natural gas to utility customers. In addition, there are various purchase commitments associated with other goods and services. At June 30, 2025, the related minimum future commitments, excluding amounts for purchased power commitments that do not have minimum thresholds but will require payment when electricity is generated by the provider, were as follows (in millions):

Alliant Energy IPL WPL
Natural gas $ 783 $ 439 $ 344
Coal 138 61 77

Other (a) 117 53 29
$ 1,038 $ 553 $ 450

(a) Includes individual commitments incurred during the normal course of business that exceeded $ 1 million at June 30, 2025.

NOTE 12(c) Guarantees and Indemnifications -
Whiting Petroleum Corporation (Whiting Petroleum) - In 2004, Alliant Energy sold its remaining interest in Whiting Petroleum, an independent oil and gas company. Alliant Energy Resources, LLC, as the successor to a predecessor entity that owned Whiting Petroleum, and a wholly-owned subsidiary of AEF, has guaranteed the partnership obligations of an affiliate of Whiting Petroleum under multiple general partnership agreements in the oil and gas industry. The guarantees do not include a maximum limit. Based on information made available to Alliant Energy by Whiting Petroleum, the Whiting Petroleum affiliate holds an approximate 6 % share in the partnerships, and currently known obligations include costs associated with the future abandonment of certain facilities owned by the partnerships. The general partnerships were formed under California law, and Alliant Energy Resources, LLC may need to perform under the guarantees if the affiliate of Whiting Petroleum is unable to meet its partnership obligations.

Whiting Petroleum previously completed bankruptcy proceedings and business combinations, which substantially reduce the likelihood that Alliant Energy will be obligated to make any payments under these guarantees. As of June 30, 2025, the currently known partnership obligations for the abandonment obligations are estimated at $ 54 million, which represents Alliant Energy’s currently estimated maximum exposure under the guarantees. Alliant Energy is not currently aware of, nor does it currently expect to incur in the future, any material liabilities related to these guarantees and therefore has not recognized any material liabilities related to these guarantees as of June 30, 2025 and December 31, 2024.

Non-utility Wind Farm in Oklahoma - In 2017, a wholly-owned subsidiary of AEF acquired a cash equity ownership interest in a non-utility wind farm located in Oklahoma. The wind farm provides electricity to a third party under a long-term purchased power agreement (PPA). Alliant Energy provided a parent guarantee of its subsidiary’s indemnification obligations under the related operating agreement and PPA. Alliant Energy’s obligations under the operating agreement were $ 43 million as of June 30, 2025 and will reduce annually until expiring in July 2047. Alliant Energy’s obligations under the PPA are subject to a maximum limit of $ 17 million and expire in December 2031, subject to potential extension. Alliant Energy is not aware of any material liabilities related to this guarantee that it is probable that it will be obligated to pay and therefore has not recognized any material liabilities related to this guarantee as of June 30, 2025 and December 31, 2024.

Transfers of Renewable Tax Credits - IPL and WPL have entered into agreements to transfer renewable tax credits from certain wind, solar and energy storage facilities to other corporate taxpayers in exchange for cash. As of June 30, 2025, IPL and WPL provided indemnifications associated with $ 266 million and $ 145 million, respectively, of proceeds for renewable tax credits transferred to other corporate taxpayers in the event of an adverse interpretation of tax law, including whether the related tax credits meet the qualification requirements. Alliant Energy, IPL and WPL believe the likelihood of having to make any material cash payments under these indemnifications is remote.

Electric Transmission Infrastructure - IPL and WPL have entered into agreements with their respective electric transmission service providers related to the construction of infrastructure necessary for the data centers that are expected to be built in IPL’s and WPL’s service territories by certain of their customers. If these construction projects were to be terminated prior to the infrastructure being placed in service by the electric transmission service providers, then IPL or WPL must reimburse their respective provider for the related costs incurred to-date. As of June 30, 2025, IPL’s and WPL’s related guarantees were approximately $ 24 million and $ 40 million, respectively. Alliant Energy, IPL and WPL are not aware of any material liabilities related to these guarantees that it is probable that they will be obligated to pay and therefore have not recognized any material liabilities related to these guarantees as of June 30, 2025.

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NOTE 12(d) Environmental Matters -
Manufactured Gas Plant (MGP) Sites - IPL and WPL have current or previous ownership interests in various sites that are previously associated with the production of gas for which IPL and WPL have, or may have in the future, liability for investigation, remediation and monitoring costs. IPL and WPL are working pursuant to the requirements of various federal and state agencies to investigate, mitigate, prevent and remediate, where necessary, the environmental impacts to property, including natural resources, at and around these former MGP sites in order to protect public health and the environment. At June 30, 2025, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, which are not discounted, were as follows (in millions):

Alliant Energy IPL WPL
Range of estimated future costs $ 8   -
$ 30 $ 6   -
$ 19 $ 2   -
$ 11
Current and non-current environmental liabilities $ 13 $ 8 $ 5

IPL Consent Decree - In 2015, the U.S. District Court for the Northern District of Iowa approved a Consent Decree that IPL entered into with the EPA, the Sierra Club, the State of Iowa and Linn County in Iowa, thereby resolving potential Clean Air Act issues associated with emissions from IPL’s coal-fired generating facilities in Iowa. IPL has completed various requirements under the Consent Decree. IPL’s remaining requirements include fuel switching or retiring Prairie Creek Units 1 and 3 by December 31, 2025. Alliant Energy and IPL currently expect to recover material costs incurred by IPL related to compliance with the terms of the Consent Decree from IPL’s electric customers.

Other Environmental Contingencies - In addition to the environmental liabilities discussed above, various environmental rules are monitored that may have a significant impact on future operations. Several of these environmental rules are subject to legal challenges, reconsideration and/or other uncertainties. Given uncertainties regarding the outcome, timing and compliance plans for these environmental matters, the complete financial impact of each of these rules is not able to be determined; however, future capital investments and/or modifications to EGUs and electric and gas distribution systems to comply with certain of these rules could be significant. Specific current, proposed or potential environmental matters include, among others: Cross-State Air Pollution Rule, Effluent Limitation Guidelines, Coal Combustion Residuals Rule, and various legislation and EPA regulations to monitor and regulate the emission of GHG, including the Clean Air Act.

NOTE 13. SEGMENTS OF BUSINESS
Certain financial information relating to Alliant Energy’s, IPL’s and WPL’s reportable segments, which represents the services provided to their customers, and reconciliation to consolidated amounts, was as follows (in millions):

Utility
Total Alliant
Reportable Energy
Three Months Ended June 30, 2025 IPL WPL Segments Other Consolidated
Electric utility revenues $ 418 $ 433 $ 851 N/A $ 851
Gas utility revenues 40 36 76 N/A 76
Other revenues 11 — 11 $ 23 34
Total revenues 469 469 938 23 961
Electric production fuel and purchased power expense 40 110 150 N/A 150
Electric transmission service expense 100 51 151 N/A 151
Cost of gas sold expense 17 13 30 N/A 30

Other operation and maintenance expense 84 72 156 12 168
Other segment items:
Depreciation and amortization expense 115 90 205 3 208
Interest expense 52 43 95 29 124
Equity income from unconsolidated investments, net — ( 1 ) ( 1 ) ( 9 ) ( 10 )
Income tax benefit ( 37 ) ( 5 ) ( 42 ) ( 1 ) ( 43 )
Other (a) — 9 9 — 9
Net income (loss) 98 87 185 ( 11 ) 174
Total assets (as of June 30, 2025)
12,180 10,236 22,416 1,334 23,750
Investments in equity method subsidiaries (as of June 30, 2025)
5 18 23 622 645
Construction and acquisition expenditures 252 170 422 61 483

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Utility
Total Alliant
Three Months Ended June 30, 2024 (amounts may not foot due to rounding)
Reportable Energy
IPL WPL Segments Other Consolidated
Electric utility revenues $ 404 $ 385 $ 789 N/A $ 789
Gas utility revenues 40 29 69 N/A 69
Other revenues 9 1 10 $ 26 36
Total revenues 453 415 868 26 894
Electric production fuel and purchased power expense 48 90 138 N/A 138
Electric transmission service expense 99 49 148 N/A 147
Cost of gas sold expense 17 8 25 N/A 25
Asset valuation charge for IPL’s Lansing Generating Station 60 — 60 N/A 60
Other operation and maintenance expense 102 67 169 8 177
Other segment items:
Depreciation and amortization expense 97 87 184 4 188
Interest expense 42 41 83 25 108
Equity income from unconsolidated investments, net — ( 1 ) ( 1 ) ( 14 ) ( 15 )
Income tax expense (benefit) ( 33 ) 3 ( 30 ) ( 3 ) ( 33 )
Other (a) 3 7 10 1 12
Net income 18 64 82 5 87
Total assets (as of June 30, 2024)
10,732 9,925 20,657 1,179 21,836
Investments in equity method subsidiaries (as of June 30, 2024)
5 17 22 584 606
Construction and acquisition expenditures 247 145 392 58 450

Utility
Total Alliant
Reportable Energy
Six Months Ended June 30, 2025 IPL WPL Segments Other Consolidated
Electric utility revenues $ 848 $ 855 $ 1,703 N/A $ 1,703
Gas utility revenues 158 158 316 N/A 316
Other revenues 24 1 25 $ 44 69
Total revenues 1,030 1,014 2,044 44 2,088
Electric production fuel and purchased power expense 107 218 325 N/A 325
Electric transmission service expense 207 101 308 N/A 308
Cost of gas sold expense 81 86 167 N/A 167

Other operation and maintenance expense 169 137 306 21 327
Other segment items:
Depreciation and amortization expense 230 183 413 7 420
Interest expense 99 86 185 58 243
Equity income from unconsolidated investments, net — ( 1 ) ( 1 ) ( 22 ) ( 23 )
Income tax benefit ( 77 ) ( 10 ) ( 87 ) ( 4 ) ( 91 )
Other (a) 5 16 21 4 25
Net income (loss) 209 198 407 ( 20 ) 387

Construction and acquisition expenditures 628 348 976 89 1,065

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Utility
Total Alliant
Six Months Ended June 30, 2024 (amounts may not foot due to rounding)
Reportable Energy
IPL WPL Segments Other Consolidated
Electric utility revenues $ 795 $ 785 $ 1,580 N/A $ 1,580
Gas utility revenues 148 125 273 N/A 273
Other revenues 23 1 24 $ 48 72
Total revenues 966 911 1,877 48 1,925
Electric production fuel and purchased power expense 116 186 302 N/A 301
Electric transmission service expense 202 98 300 N/A 300
Cost of gas sold expense 77 62 139 N/A 139
Asset valuation charge for IPL’s Lansing Generating Station 60 — 60 N/A 60
Other operation and maintenance expense 187 128 315 21 336
Other segment items:
Depreciation and amortization expense 193 178 371 5 376
Interest expense 84 82 166 49 215
Equity income from unconsolidated investments, net — ( 1 ) ( 1 ) ( 30 ) ( 31 )
Income tax expense (benefit) ( 43 ) 8 ( 35 ) ( 8 ) ( 43 )
Other (a) 9 14 23 3 27
Net income 81 156 237 8 245

Construction and acquisition expenditures 500 370 870 90 960

(a) Other segment items for each reportable segment include allowance for funds used during construction, taxes other than income taxes, interest income, and other miscellaneous income and deductions.

NOTE 14. RELATED PARTIES
Service Agreements - Pursuant to service agreements, IPL and WPL receive various administrative and general services from an affiliate, Corporate Services. These services are billed to IPL and WPL at cost based on expenses incurred by Corporate Services for the benefit of IPL and WPL, respectively. These costs consisted primarily of employee compensation and benefits, fees associated with various professional services, depreciation and amortization of property, plant and equipment, and a return on net assets. Corporate Services also acts as agent on behalf of IPL and WPL pursuant to the service agreements. As agent, Corporate Services enters into energy, capacity, ancillary services, and transmission sale and purchase transactions within MISO. Corporate Services assigns such sales and purchases among IPL and WPL based on statements received from MISO. The amounts billed for services provided, sales credited and purchases for the three and six months ended June 30 were as follows (in millions):

IPL WPL
Three Months Six Months Three Months Six Months
2025 2024 2025 2024 2025 2024 2025 2024
Corporate Services billings $ 50 $ 49 $ 97 $ 92 $ 48 $ 46 $ 95 $ 86
Sales credited 1 — 2 — 40 14 62 36
Purchases billed 107 105 200 201 16 16 35 23

Net intercompany payables to Corporate Services were as follows (in millions):

IPL WPL
June 30, 2025 December 31, 2024 June 30, 2025 December 31, 2024
Net payables to Corporate Services $ 135 $ 135 $ 50 $ 64

ATC - Pursuant to various agreements, WPL receives a range of transmission services from ATC. WPL provides operation, maintenance, and construction services to ATC. WPL and ATC also bill each other for use of shared facilities owned by each party. The related amounts billed between the parties for the three and six months ended June 30 were as follows (in millions):

Three Months Six Months
2025 2024 2025 2024
ATC billings to WPL $ 38 $ 39 $ 76 $ 76
WPL billings to ATC 5 4 11 7

WPL owed ATC net amounts of $ 10 million as of June 30, 2025 and $ 10 million as of December 31, 2024.

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ITEM 2. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

This MDA includes information relating to Alliant Energy, and IPL and WPL (collectively, the Utilities), as well as ATC Holdings, AEF and Corporate Services. Where appropriate, information relating to a specific entity has been segregated and labeled as such. The following discussion and analysis should be read in conjunction with the Financial Statements and the Notes included in this report, as well as the financial statements, notes and MDA included in the 2024 Form 10-K . Unless otherwise noted, all “per share” references in MDA refer to earnings per diluted share.

2025 HIGHLIGHTS

Key highlights since the filing of the 2024 Form 10-K include the following:

Customer Investments:
• Over the next six years, Alliant Energy currently plans to develop and/or acquire new generation investments to add flexibility with evolving load growth, including approximately 1,500 MW of new natural gas resources, approximately 1,200 MW of new wind generation, approximately 800 MW of new energy storage, refurbishments at approximately 500 MW of existing wind farms, improvements of approximately 280 MW at existing natural gas-fired EGUs, and the conversion of existing coal-fired EGUs to natural gas. Alliant Energy is currently evaluating the impact of potential additional large load growth customers and MISO’s seasonal resource adequacy requirements on its resource plans and will update these generation investment plans as needed in the future. Estimated capital expenditures for these planned projects for 2025 through 2028 are included in the “Generation” section in the construction and acquisition table in “ Liquidity and Capital Resources .” Information on IPL’s and WPL’s regulatory filings and/or approvals for future generation and energy storage projects are as follows:
• In February 2025, WPL filed a certificate of authority (CA) application with the PSCW for approval to construct a 2 billion cubic feet, or 25 million gallon, liquified natural gas facility in Rock County, Wisconsin. A decision from the PSCW is currently expected in the second quarter of 2026.
• In April 2025, the PSCW issued an order authorizing WPL to construct, own and operate a 17.5 MW natural gas-fired EGU using Reciprocating Internal Combustion Engine (RICE) technology, at the site of its Riverside Energy Center.
• In April 2025, WPL filed a CA application with the PSCW for approval to construct, own and operate the Bent Tree North EGU, an approximate 153 MW wind farm. A decision from the PSCW is currently expected in the second quarter of 2026.
• In May 2025, the PSCW issued an order authorizing WPL to refurbish the Bent Tree wind farm.
• In May 2025, IPL filed a certificate of public convenience, use and necessity (GCU Certificate) application with the IUC for approval to construct, own and operate up to 75 MW of energy storage at the site of its Golden Plains wind farm. A decision from the IUC is currently expected in the fourth quarter of 2025.
• In May 2025, IPL filed a GCU Certificate application with the IUC for approval to construct, own and operate up to 75 MW of energy storage at the site of its Whispering Willow - North wind farm. A decision from the IUC is currently expected in the fourth quarter of 2025.
• In June 2025, the IUC issued an order authorizing IPL to construct, own and operate the Cedar River Generating Station, a 94 MW natural gas-fired EGU using RICE technology, at the site of its Prairie Creek Generating Station.
• In June 2025, the PSCW issued an order authorizing WPL to construct, own and operate an approximately 20 MW compressed carbon dioxide-based long-duration energy storage system at the site of its Columbia Energy Center.
• In July 2025, IPL filed for advance rate-making principles with the IUC for up to 1,000 MW of new wind generation in Iowa. The advance rate-making principles filing included requests for a fixed cost cap of $3,020/kilowatt, including allowance for funds used during construction and transmission upgrade costs among other costs, and a return on common equity of 11.25%. A decision from the IUC is currently expected in the first quarter of 2026.
• In July 2025, the IUC issued an order authorizing IPL to construct, own and operate up to 150 MW of energy storage at the site of its retired Lansing Generating Station.
• In July 2025, WPL completed construction of approximately 100 MW of energy storage at the site of its Grant County solar facility.

Rate Matters:
• In March 2025, WPL filed a retail electric and gas rate review with the PSCW for the 2026/2027 forward-looking Test Period. The key drivers for the filing include revenue requirement impacts of increasing electric and gas rate base, including wind refurbishment projects, energy storage, existing natural gas-fired EGU improvements, solar generation costs incurred that exceed the construction cost estimates previously approved by the PSCW, and electric and gas distribution investments. The filing requested approval for WPL to implement increases in annual rates for its retail electric and gas customers of $120 million and $9 million in 2026, respectively, with any granted rate changes expected to be effective on January 1, 2026. WPL’s filing also requested approval to implement an additional increase in annual rates for its retail electric and gas customers of $82 million and $5 million in 2027, respectively, with any granted rate changes expected to be effective on January 1, 2027. WPL also requested a return on common equity of 9.9% and to implement a common equity component of its regulatory capital structure of 55.5% in 2026 and 55.3% in 2027. WPL’s filing also requested an extension, with certain modifications, of its current earnings sharing mechanism through 2027, including deferral of a portion of its earnings if its annual regulatory return on common equity exceeds 10.15% during the 2026/2027 Test Period (deferral of 50% of its excess earnings between 10.15% and 10.65%, and 100% of any excess earnings above 10.65%). A decision from the PSCW is currently expected by the end of 2025.

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Growing Customer Demand:
• WPL has entered into an electric service agreement with a new customer, who currently expects to build a data center at the Beaver Dam Commerce Park in Beaver Dam, Wisconsin in WPL’s service territory. The actual timing and amount of increases in WPL’s load are subject to various factors, including interconnections and actual customer demand, and any executed or future agreements with customers are not expected to result in immediate increases in load. IPL’s and WPL’s currently executed electric service agreements include aggregate, maximum demands of approximately 2.1 gigawatts.
• In May 2025, the IUC issued an order, with certain conditions, approving individual customer rates associated with certain of the data centers expected to be constructed in IPL’s service territory. In June 2025 and April 2025, IPL and WPL filed requests with the IUC and PSCW, respectively, for approval of the individual customer rates associated with certain of the data centers expected to be constructed in their service territories, with decisions from the IUC and PSCW currently expected by the end of the third quarter of 2025.

Environmental Matters and Stewardship:
• In March 2025, the EPA announced it expects to initiate a formal reconsideration of various environmental regulations and programs, including the Cross-State Air Pollution Rule and Effluent Limitation Guidelines. In June 2025, the EPA proposed to repeal Clean Air Act Sections 111(b) and 111(d). In July 2025, the EPA proposed to repeal its 2009 ruling that found GHG contributes to climate change and gave it authority to regulate GHG under the Clean Air Act. The EPA also expects to expedite review of state programs to delegate implementation of the Coal Combustion Residuals Rule and reconsider compliance deadlines. Alliant Energy, IPL and WPL are currently unable to predict with certainty the future outcome or impact of these matters, including resolution of ongoing and potential litigation.
• Alliant Energy’s current voluntary environmental stewardship goals include the following:
• By 2030, reduce GHG emissions from its utility operations by 50% from 2005 levels, reduce its electric utility water supply by 75% from 2005 levels and electrify 100% of its owned light-duty fleet vehicles.
• By 2040, eliminate all coal-fired EGUs from its generating fleet.
• By 2050, aspire to achieve net-zero GHG emissions from its utility operations.
• Alliant Energy’s aspirational GHG goal includes EPA reportable emissions based on applicable regulatory compliance requirements for carbon dioxide, methane and nitrous oxide from its owned fossil-fueled EGUs and distribution of natural gas. Alliant Energy’s voluntary environmental stewardship goals may be revised, or their achievement may be delayed, based on increasing customer energy needs, reliability and resource adequacy requirements, and tax policy changes, and the ability to achieve these goals is subject to various additional risk factors included in the 2024 Form 10-K . These goals are not meant to be considered guidance.

Legislative Matters:
• In July 2025, the One Big Beautiful Bill Act was enacted, which modifies various clean energy tax credits under the Inflation Reduction Act of 2022, including production tax credits and investment tax credits. The most significant provisions of the new legislation for Alliant Energy, IPL and WPL relate to the accelerated phase out of clean energy tax credits for eligible projects for which construction begins more than 12 months after the date of enactment or for projects placed in service after 2027, and restricted access to clean energy tax credits for projects that begin construction after 2025 and receive impermissible amounts of construction support from entities with ties to certain foreign countries, including China. Additionally, in July 2025, the Presidential Administration directed the U.S. Department of the Treasury to strictly enforce the termination of clean energy tax credits, including issuing new and revised guidance by September 2025, to ensure that requirements concerning the beginning of construction are not circumvented. Refer to “ 2025 Highlights ” for discussion of Alliant Energy’s, IPL’s and WPL’s current plans to develop and/or acquire new clean energy resources. Alliant Energy, IPL and WPL currently expect these clean energy projects would continue to be eligible for clean energy tax credits. If these clean energy projects do not begin construction within the anticipated timeframes or fail to meet other eligibility requirements, the amount of clean energy tax credits could be significantly reduced, which could adversely impact Alliant Energy’s, IPL’s and WPL’s financial condition and results of operations.

Financings:
• Refer to “ Results of Operations ” for discussion of expected future issuances and retirements of long-term debt in 2025.
• In April 2025, WPL submitted an application to the U.S. Army Corps of Engineers for up to $45 million in loans through the Corps Water Infrastructure Financing Program. If finalized, such loans would provide low interest financing for various proposed safety projects at WPL’s Kilbourn and Prairie du Sac hydro EGUs.

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RESULTS OF OPERATIONS

Financial Results Overview - The table below includes diluted EPS for Utilities and Corporate Services, ATC Holdings, and Non-utility and Parent, which are non-GAAP financial measures. Alliant Energy believes these non-GAAP financial measures are useful to investors because they facilitate an understanding of performance and trends, and provide additional information about Alliant Energy’s operations on a basis consistent with the measures that management uses to manage its operations and evaluate its performance. Alliant Energy’s net income and EPS attributable to Alliant Energy common shareowners for the three months ended June 30 were as follows (dollars in millions, except per share amounts):

2025 2024
Income (Loss) EPS Income (Loss) EPS

Utilities and Corporate Services $190 $0.74 $85 $0.33
ATC Holdings 10 0.04 9 0.04
Non-utility and Parent (26) (0.10) (7) (0.03)

Alliant Energy Consolidated $174 $0.68 $87 $0.34

Alliant Energy’s Utilities and Corporate Services net income increased by $105 million for the three-month period, primarily due to higher revenue requirements from IPL’s and WPL’s capital investments, an asset valuation charge in 2024 for IPL’s retired Lansing Generating Station, an ARO charge in 2024 allocated to the steam business at IPL due to the revised Coal Combustion Residuals Rule, and estimated temperature impacts on retail electric and gas sales. These items were partially offset by higher depreciation and financing expenses.

Alliant Energy’s Non-utility and Parent net income decreased $19 million for the three-month period, primarily due to lower equity income from corporate venture investments, higher financing expense and the timing of income taxes.

Net Income Variances - The following items contributed to increased (decreased) net income for the three and six months ended June 30, 2025 compared to the same periods in 2024 (in millions):

Three Months Six Months
Alliant Energy IPL WPL Alliant Energy IPL WPL
Revenues:
Changes in electric utility (Refer to details below )
$62 $14 $48 $123 $53 $70
Changes in gas utility (Refer to details below )
7 — 7 43 10 33
Changes in other utility 1 2 (1) 1 1 —
Changes in non-utility (3) — — (4) — —
Changes in total revenues 67 16 54 163 64 103
Operating expenses:
Changes in electric production fuel and purchased power (Refer to details below )
(12) 8 (20) (24) 9 (32)
Changes in electric transmission service (Refer to details below )
(4) (1) (2) (8) (5) (3)
Changes in cost of gas sold (Refer to details below )
(5) — (5) (28) (4) (24)
Asset valuation charge for IPL’s Lansing Generating Station in 2024 (Refer to Note 2 for details)
60 60 — 60 60 —
Changes in other operation and maintenance (Refer to details below )
9 18 (5) 9 18 (9)
Changes in depreciation and amortization (Higher primarily due to solar generation placed in service in 2024 and updated electric depreciation rates for IPL effective October 1, 2024) (20) (18) (3) (44) (37) (5)
Changes in taxes other than income taxes (2) (1) (1) (1) 1 (1)
Changes in total operating expenses 26 66 (36) (36) 42 (74)
Changes in operating income 93 82 18 127 106 29
Other income and deductions:
Changes in interest expense (Higher primarily due to financings completed in 2024 and 2025) (16) (10) (2) (28) (15) (4)
Changes in equity income from unconsolidated investments, net (Refer to Note 4 for details)
(5) — — (8) — —
Changes in allowance for funds used during construction 4 2 2 3 1 2
Changes in Other 1 2 (3) — 2 (3)
Changes in total other income and deductions (16) (6) (3) (33) (12) (5)
Changes in income before income taxes 77 76 15 94 94 24
Changes in income taxes (Refer to Note 8 for details)
10 4 8 48 34 18

Changes in net income $87 $80 $23 $142 $128 $42

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Electric and Gas Revenues and Sales Summary - Electric and gas revenues (in millions), and MWh and Dth sales (in thousands), for the three and six months ended June 30 were as follows:

Alliant Energy Electric Gas
Revenues MWhs Sold Revenues Dths Sold
2025 2024 2025 2024 2025 2024 2025 2024
Three Months
Retail $746 $719 5,926 5,948 $64 $59 6,114 5,730
Sales for resale:
Wholesale 49 43 651 653 N/A N/A N/A N/A
Bulk power and other 43 13 1,176 1,087 N/A N/A N/A N/A
Transportation/Other 13 14 14 14 12 10 27,159 29,102
$851 $789 7,767 7,702 $76 $69 33,273 34,832
Six Months
Retail $1,518 $1,425 12,100 11,937 $290 $251 29,936 25,848
Sales for resale:
Wholesale 97 89 1,342 1,333 N/A N/A N/A N/A
Bulk power and other 69 34 2,554 2,757 N/A N/A N/A N/A
Transportation/Other 19 32 28 29 26 22 58,165 63,009
$1,703 $1,580 16,024 16,056 $316 $273 88,101 88,857

IPL Electric Gas
Revenues MWhs Sold Revenues Dths Sold
2025 2024 2025 2024 2025 2024 2025 2024
Three Months
Retail $395 $387 3,286 3,291 $33 $34 2,667 2,679
Sales for resale:
Wholesale 14 13 161 173 N/A N/A N/A N/A
Bulk power and other 1 (2) 301 205 N/A N/A N/A N/A
Transportation/Other 8 6 8 8 7 6 10,295 9,590
$418 $404 3,756 3,677 $40 $40 12,962 12,269
Six Months
Retail $804 $762 6,724 6,656 $142 $135 14,439 12,885
Sales for resale:
Wholesale 28 26 343 356 N/A N/A N/A N/A
Bulk power and other 2 (5) 697 529 N/A N/A N/A N/A
Transportation/Other 14 12 16 16 16 13 22,366 21,284
$848 $795 7,780 7,557 $158 $148 36,805 34,169

WPL Electric Gas
Revenues MWhs Sold Revenues Dths Sold
2025 2024 2025 2024 2025 2024 2025 2024
Three Months
Retail $351 $332 2,640 2,657 $31 $25 3,447 3,051
Sales for resale:
Wholesale 35 30 490 480 N/A N/A N/A N/A
Bulk power and other 42 15 875 882 N/A N/A N/A N/A
Transportation/Other 5 8 6 6 5 4 16,864 19,512
$433 $385 4,011 4,025 $36 $29 20,311 22,563
Six Months
Retail $714 $663 5,376 5,281 $148 $116 15,497 12,963
Sales for resale:
Wholesale 69 63 999 977 N/A N/A N/A N/A
Bulk power and other 67 39 1,857 2,228 N/A N/A N/A N/A
Transportation/Other 5 20 12 13 10 9 35,799 41,725
$855 $785 8,244 8,499 $158 $125 51,296 54,688

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Sales Trends and Temperatures - All iant Energy’s retail electric sa les volumes were unchanged and increased 1% for the three and six months ended June 30, 2025, respectively, compared to the same periods in 2024, primarily due to changes in temperatures. Alliant Energy’s retail gas sales volumes increased 7% and 16% for the three and six months ended June 30, 2025, respectively, compared to the same periods in 2024, primarily due to changes in temperatures.

Estimated increases (decreases) to operating income from the impacts of temperatures for the three and six months ended June 30 were as follows (in millions):

Electric Gas
Three Months Six Months Three Months Six Months
2025 2024 Change 2025 2024 Change 2025 2024 Change 2025 2024 Change
IPL $4 $1 $3 $— ($8) $8 ($1) ($1) $— ($3) ($7) $4
WPL 3 (2) 5 — (12) 12 — (2) 2 (1) (7) 6
Total Alliant Energy $7 ($1) $8 $— ($20) $20 ($1) ($3) $2 ($4) ($14) $10

Electric Sales for Resale - Bulk Power and Other - Bulk power and other volume changes were due to changes in sales in the wholesale energy markets operated by MISO. These changes are impacted by several factors, including the availability and dispatch of Alliant Energy’s EGUs and electricity demand within these wholesale energy markets. Changes in bulk power and other revenues were largely offset by changes in fuel-related costs, and therefore did not have a significant impact on operating income.

Gas Transportation/Other - Gas transportation/other sales volume changes were largely due to changes in the gas volumes supplied to Alliant Energy’s natural gas-fired EGUs caused by the availability and dispatch of such EGUs.

Electric Utility Revenue Variances - The following items contributed to increased (decreased) electric utility revenues for the three and six months ended June 30, 2025 compared to the same periods in 2024 (in millions):

Three Months Six Months
Alliant Energy IPL WPL Alliant Energy IPL WPL

Higher revenue requirements (a)(b) $94 $79 $15 $202 $172 $30
Higher sales for resale bulk power and other revenues (c) 30 3 27 35 7 28
Estimated changes in sales volumes caused by temperatures 8 3 5 20 8 12

Changes in WPL electric fuel-related costs, net of recoveries (d) 11 — 11 6 — 6
Lower revenues at IPL due to credits on customers’ bills related to production tax credits through its fuel-related cost recovery mechanism (offset by changes in income taxes) (a) (38) (38) — (89) (89) —
Lower revenues at IPL due to credits on customers’ bills through the tax benefit rider in 2025 (partially offset by changes in income taxes) (a) (16) (16) — (34) (34) —
Higher (lower) revenues primarily due to changes in retail electric fuel-related costs (Refer to Electric Production Fuel and Purchased Power Expenses Variances below)
(25) (18) (7) (14) (18) 4
Other (2) 1 (3) (3) 7 (10)
$62 $14 $48 $123 $53 $70

(a) In September 2024, the IUC issued an order authorizing an annual base rate increase of $185 million for IPL’s retail electric customers, with customers receiving partially offsetting credits for the first 12 months through a tax benefit rider, for the October 2024 through September 2025 forward-looking Test Period. Rate changes were effective October 1, 2024, which reflect revenue requirement impacts of increasing electric rate base including investments in solar generation, updated depreciation rates, and certain incremental costs incurred resulting from the 2020 derecho windstorm. In addition, effective October 1, 2024, IPL’s renewable energy rider was discontinued, and certain production tax credits are credited to IPL’s retail electric customers through IPL’s fuel-related cost recovery mechanism. Credits on IPL’s customers’ bills have been and are expected to be offset by a reduction in income tax expense.
(b) In December 2023, the PSCW issued an order authorizing an annual base rate increase of $60 million for WPL’s retail electric customers, covering the 2025 forward-looking Test Period, which reflects revenue requirement impacts of increasing electric rate base including investments in solar generation and energy storage.
(c) Alliant Energy’s and WPL’s sales for resale bulk power and other revenues increased primarily due to higher prices for electricity and capacity sold by WPL to MISO wholesale energy markets. These changes were largely offset by changes in fuel-related costs.

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(d) WPL’s cost recovery mechanism for retail fuel-related expenses supports deferrals of amounts that fall outside an approved fuel monitoring range of forecasted fuel-related expenses determined by the PSCW each year. The difference between revenue collected and actual fuel-related expenses incurred within the fuel monitoring range increases or decreases Alliant Energy’s and WPL’s electric utility revenues. WPL estimates the increase (decrease) to electric utility revenues from amounts within the fuel monitoring range were approximately $6 million and $2 million for the three and six months ended June 30, 2025, respectively, compared to ($5) million and ($4) million for the three and six months ended June 30, 2024, respectively.

Gas Utility Revenue Variances - The following items contributed to increased (decreased) gas utility revenues for the three and six months ended June 30, 2025 compared to the same periods in 2024 (in millions):

Three Months Six Months
Alliant Energy IPL WPL Alliant Energy IPL WPL
Higher revenues due to changes in gas costs (Refer to Cost of Gas Sold Expense Variances below)
$5 $— $5 $28 $4 $24
Estimated changes in sales volumes caused by temperatures 2 — 2 10 4 6
Higher revenue requirements (a) 1 1 — 5 5 —

Other (1) (1) — — (3) 3
$7 $— $7 $43 $10 $33

(a) In September 2024, the IUC issued an order authorizing an annual base rate increase of $10 million for IPL’s retail gas customers, for the October 2024 through September 2025 forward-looking Test Period. Rate changes were effective October 1, 2024, which reflect revenue requirement impacts of increasing gas rate base.

Electric Production Fuel and Purchased Power Expenses Variances - The following items contributed to (increased) decreased electric production fuel and purchased power expenses for the three and six months ended June 30, 2025 compared to the same periods in 2024 (in millions):

Three Months Six Months
Alliant Energy IPL WPL Alliant Energy IPL WPL
Higher electric production fuel costs (a) ($21) ($12) ($9) ($27) ($17) ($10)
Lower (higher) purchased power expense (b) 4 2 2 (10) 4 (14)
Changes in regulatory recovery of retail electric fuel-related costs 8 19 (11) 13 22 (9)

Other (3) (1) (2) — — 1
($12) $8 ($20) ($24) $9 ($32)

(a) Electric production fuel costs increased for the three and six months ended June 30, 2025, compared to the same periods in 2024, primarily due to higher coal volumes due to higher dispatch of coal-fired EGUs and higher natural gas prices, partially offset by lower natural gas volumes due to lower dispatch of natural gas-fired EGUs.
(b) Purchased power expense increased for the six months ended June 30, 2025 compared to the same period in 2024, primarily due to higher prices for electricity purchased at WPL.

Electric Transmission Service Expense Variances - The following items contributed to (increased) decreased electric transmission service expense for the three and six months ended June 30, 2025 compared to the same periods in 2024 (in millions):

Three Months Six Months
Alliant Energy IPL WPL Alliant Energy IPL WPL

Changes in regulatory recovery for the difference between actual electric transmission service costs and those costs used to determine rates $4 $1 $3 $7 $1 $6

Other (primarily due to changes in transmission service costs provided by third parties) (8) (2) (5) (15) (6) (9)
($4) ($1) ($2) ($8) ($5) ($3)

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Cost of Gas Sold Expense Variances - The following items contributed to (increased) decreased cost of gas sold expense for the three and six months ended June 30, 2025 compared to the same periods in 2024 (in millions):

Three Months Six Months
Alliant Energy IPL WPL Alliant Energy IPL WPL
Higher retail gas volumes and changes in natural gas prices ($10) ($1) ($9) ($22) ($6) ($16)
Changes in the regulatory recovery of gas costs 5 1 4 (6) 2 (8)

($5) $— ($5) ($28) ($4) ($24)

Other Operation and Maintenance Expenses Variances - The following items contributed to (increased) decreased other operation and maintenance expenses for the three and six months ended June 30, 2025 compared to the same periods in 2024 (in millions):

Three Months Six Months
Alliant Energy IPL WPL Alliant Energy IPL WPL

ARO charge in 2024 for steam assets at IPL (Refer to Note 1 ( c) for details)
$20 $20 $— $20 $20 $—

Other (primarily due to higher generation expense) (11) (2) (5) (11) (2) (9)
$9 $18 ($5) $9 $18 ($9)

Other Future Considerations - In addition to items discussed in this report, the following key items could impact Alliant Energy’s, IPL’s and WPL’s future financial condition or results of operations:
• Financing Plans - Alliant Energy currently expects to issue up to $1.3 billion of common stock in aggregate from 2026 through 2028 through the distribution agreement that was executed in May 2025, and up to $25 million of common stock annually through its Shareowner Direct Plan in 2025 through 2028. For the remainder of 2025, IPL and WPL currently expect to issue up to $400 million and $300 million, respectively, of long-term debt, and AEF and/or Alliant Energy at the parent company level expect to issue up to $725 million of long-term debt in aggregate. IPL has $250 million of long-term debt maturing in August 2025.

LIQUIDITY AND CAPITAL RESOURCES

The liquidity and capital resources summary included in the 2024 Form 10-K has not changed materially, except as described below.

Liquidity Position - At June 30, 2025, Alliant Energy had $329 million of cash and cash equivalents, $1,008 million ($550 million at the parent company, $350 million at IPL and $108 million at WPL) of available capacity under the single revolving credit facility and $4 million of available capacity at IPL under its sales of accounts receivable program.

Capital Structure - Financial capital structures at June 30, 2025 were as follows (Long-term Debt (including current maturities) (LD); Short-term Debt (SD); Common Equity (CE)):

Cash Flows - Selected information from the cash flows statements was as follows (in millions):

Alliant Energy IPL WPL
2025 2024 2025 2024 2025 2024
Cash, cash equivalents and restricted cash, January 1 $81 $63 $29 $53 $51 $7
Cash flows from (used for):
Operating activities 492 562 108 147 337 391
Investing activities (894) (533) (441) (209) (362) (247)
Financing activities 650 1 508 18 (16) (71)
Net increase (decrease) 248 30 175 (44) (41) 73
Cash, cash equivalents and restricted cash, June 30
$329 $93 $204 $9 $10 $80

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Operating Activities - The following items contributed to increased (decreased) operating activity cash flows for the six months ended June 30, 2025 compared to the same period in 2024 (in millions):

Alliant Energy IPL WPL
Lower collections from IPL’s retail customers due to credits on customers’ bills related to production tax credits through its fuel-related cost recovery mechanism ($89) ($89) $—
Lower collections from IPL’s retail customers due to credits on customers’ bills related to the tax benefit rider (34) (34) —
Changes in interest payments (32) (12) (12)

Restructuring and voluntary employee separation payments in 2025 (25) (11) (12)
Higher collections from IPL’s and WPL’s retail electric and IPL’s gas base rate increases 207 177 30
Increased collections from IPL’s and WPL’s retail customers caused by temperature impacts on electric and gas sales 30 12 18

Changes in income taxes paid/received (a) 2 (24) 18
Other (primarily due to other changes in working capital) (129) (58) (96)
($70) ($39) ($54)

(a) Refer to the cash flows statements for details of renewable tax credits transferred to other corporate taxpayers during the six months ended June 30, 2025 and 2024.

Investing Activities - The following items contributed to increased (decreased) investing activity cash flows for the six months ended June 30, 2025 compared to the same period in 2024 (in millions):

Alliant Energy IPL WPL
Proceeds from sales of partial ownership interests in West Riverside in 2024 ($123) $— ($123)
Changes in the amount of cash receipts on sold receivables (108) (108) —
(Higher) lower utility construction and acquisition expenditures (a) (106) (128) 22

Other (24) 4 (14)
($361) ($232) ($115)

(a) Largely due to higher expenditures for IPL’s energy storage, partially offset by lower expenditures for IPL’s and WPL’s solar generation.

Construction and Acquisition Expenditures - Construction and acquisition expenditures and financing plans are reviewed, approved and updated as part of the strategic planning process. Changes may result from a number of reasons, including changes in expected load growth, regulatory requirements, changing legislation, not obtaining favorable and acceptable regulatory approval on certain projects, changing costs of projects due to market conditions and the impact of tariffs, improvements in technology, and improvements to ensure resiliency and reliability of the electric and gas distribution systems. Alliant Energy, IPL and WPL have not yet entered into contractual commitments relating to the majority of their anticipated future construction and acquisition expenditures. As a result, they have some discretion with regard to the level and timing of these expenditures. Construction and acquisition expenditures for 2025 through 2028 are currently anticipated as follows (in millions), which are focused on adding generation to meet growing customer demand for electricity, including expected future data center growth from currently executed electric service agreements, and strengthening the resiliency and reliability of the electric grid, and include renewable generation and energy storage projects, dispatchable gas generation projects, and converting certain coal-fired EGUs to natural gas. Alliant Energy, IPL and WPL are currently evaluating the impacts of tariffs, recently enacted legislation and additional potential large load growth customers on their resource plans, and will update their anticipated construction and acquisition expenditures as needed in the future. Cost estimates represent Alliant Energy’s, IPL’s and WPL’s portion of construction expenditures and exclude allowance for funds used during construction and capitalized interest, if applicable.

Alliant Energy IPL WPL
2025 2026 2027 2028 2025 2026 2027 2028 2025 2026 2027 2028
Generation:
Renewables and energy storage projects $995  $895  $1,125  $1,160  $675  $480  $580  $660  $320  $415  $545  $500 
Gas projects 460  740  1,025  885  240  320  615  645  170  385  410  240 
Other 145  135  70  65  65  60  30  15  80  75  40  50 
Distribution:
Electric systems 595  625  600  580  325  265  250  255  270  360  350  325 
Gas systems 100  130  160  105  55  70  90  40  45  60  70  65 
Other 215  230  225  245  45  35  45  50  35  30  35  25 
$2,510  $2,755  $3,205  $3,040  $1,405  $1,230  $1,610  $1,665  $920  $1,325  $1,450  $1,205 

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Financing Activities - The following items contributed to increased (decreased) financing activity cash flows for the six months ended June 30, 2025 compared to the same period in 2024 (in millions):

Alliant Energy IPL WPL
Lower payments to retire long-term debt $305 $— $—
Higher (lower) net proceeds from issuance of long-term debt 193 594 (297)
Net changes in the amount of commercial paper outstanding 157 (50) 427

Higher (lower) capital contributions from IPL’s and WPL’s parent company, Alliant Energy — 20 (55)
Higher common stock dividends (15) (80) (21)

Other 9 6 1
$649 $490 $55

Common Stock Issuances - Refer to Note 5 for discussion of common stock issuances by Alliant Energy in 2025 and Alliant Energy’s at-the-market offering program. Refer to “ Results of Operations ” for discussion of expected future issuances of common stock from 2025 through 2028.

Long-term Debt - Refer to Note 6(b) for discussion of AEF’s term loan credit agreements and various issuances and/or retirements of long-term debt by Alliant Energy and IPL in 2025. Refer to “ Results of Operation s ” for discussion of expected future issuances and retirements of long-term debt in 2025.

Impact of Credit Ratings on Liquidity and Collateral Obligations -
Ratings Triggers - In March 2025, Standard & Poor’s Ratings Services changed certain Alliant Energy, IPL and WPL credit ratings and outlooks, which are not expected to have a material impact on Alliant Energy’s, IPL’s and WPL’s liquidity or collateral obligations, and the current credit ratings and outlooks are as follows: