Alliant Energy 10-Q 2025-03-31

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 March 31, 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 CORPORATION

(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 COMPANY

(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 COMPANY

(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 March 31, 2025:

Alliant Energy Corporation, Common Stock, $0.01 par value, 256,876,299 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			1
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			13
6. Debt			15
7. Revenues			16
8. Income Taxes			16
9. Benefit Plans			16
10. Derivative Instruments			17
11. Fair Value Measurements			18
12. Commitments and Contingencies			20
13. Segments of Business			22
14. Related Parties			23
Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations			23
Item 3. Quantitative and Qualitative Disclosures About Market Risk			30
Item 4. Controls and Procedures			30
Part II. Other Information			31
Item 1. Legal Proceedings			31
Item 1A. Risk Factors			31
Item 2. Unregistered Sales of Equity Securities and Use of Proceeds			31
Item 5. Other Information			31
Item 6. Exhibits			32
Signatures			32

Table of Contents

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.			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
GAAP			U.S. generally accepted accounting principles			WPL			Wisconsin Power and Light Company

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 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 construction projects with acceptable conditions;

• the ability to achieve the expected level of tax benefits based on tax guidelines, timely in-service dates, 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;

• 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;

• federal and state regulatory or governmental actions, including the impact of legislation, regulatory agency orders and executive orders, and changes in public policy, including the potential repeal of the Inflation Reduction Act of 2022;

• 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;

			1

Table of Contents

• 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;

• 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;

• 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, 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 greenhouse gases 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, including start-up risks, breakdown or failure of equipment, 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.

			2

Table of Contents

PART I. FINANCIAL INFORMATION

ALLIANT ENERGY CORPORATION

CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED)

			For the Three Months
			Ended March 31,
			2025						2024
			(in millions, except per share amounts)
Revenues:
Electric utility			$853						$791
Gas utility			240						205
Other utility			13						13
Non-utility			22						22
Total revenues			1,128						1,031
Operating expenses:
Electric production fuel and purchased power			175						163
Electric transmission service			158						152
Cost of gas sold			137						114
Other operation and maintenance			160						160
Depreciation and amortization			211						189
Taxes other than income taxes			30						31
Total operating expenses			871						809
Operating income			257						222
Other (income) and deductions:
Interest expense			119						107
Equity income from unconsolidated investments, net			(13)						(15)
Allowance for funds used during construction			(18)						(19)
Other			3						1
Total other (income) and deductions			91						74
Income before income taxes			166						148
Income tax benefit			(47)						(10)
Net income attributable to Alliant Energy common shareowners			$213						$158
Weighted average number of common shares outstanding:
Basic			256.8						256.2
Diluted			257.2						256.5
Earnings per weighted average common share attributable to Alliant Energy common shareowners (basic and diluted)			$0.83						$0.62

Refer to accompanying Combined Notes to Condensed Consolidated Financial Statements.

			3

Table of Contents

ALLIANT ENERGY CORPORATION

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED)

			March 31, 2025						December 31, 2024
			(in millions, except per share and share amounts)
ASSETS
Current assets:
Cash and cash equivalents			$25						$81
Accounts receivable, less allowance for expected credit losses			361						427
Production fuel, at weighted average cost			53						54
Gas stored underground, at weighted average cost			16						55
Materials and supplies, at weighted average cost			196						186
Regulatory assets			172						210
Other			146						171
Total current assets			969						1,184
Property, plant and equipment, net			19,022						18,701
Investments:
ATC Holdings			426						415
Other			224						224
Total investments			650						639
Other assets:
Regulatory assets			2,102						2,064
Deferred charges and other			108						126
Total other assets			2,210						2,190
Total assets			$22,851						$22,714

LIABILITIES AND EQUITY
Current liabilities:

Showing the first 8K of 134K characters. Open the full section

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 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 Rock County, Wisconsin.

			23

Table of Contents

• In April 2025, WPL filed a certificate of authority application with the PSCW for approval to construct, own and operate the Bent Tree North EGU, an approximate 153 MW wind farm in Freeborn County, Minnesota, which would be eligible for production tax credits under the Inflation Reduction Act of 2022. A decision from the PSCW is currently expected in the second quarter of 2026.

• In April 2025, IPL filed a certificate of public convenience, use and necessity application with the IUC for approval to construct, own and operate up to 150 MW of energy storage at the site of its retired Lansing Generating Station in Iowa, which would be eligible for investment tax credits under the Inflation Reduction Act of 2022. A decision from the IUC is currently expected in the fourth quarter of 2025.

• In May 2025, the PSCW issued an order authorizing WPL to refurbish the Bent Tree wind farm, which would be eligible for production tax credits under the Inflation Reduction Act of 2022.

• In May 2025, IPL filed a certificate of public convenience, use and necessity 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 in Iowa, which would be eligible for investment tax credits under the Inflation Reduction Act of 2022. A decision from the IUC is currently expected in the fourth quarter of 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.

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.

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 February 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. Decisions from the IUC and PSCW are currently expected by the end of the third quarter of 2025.

Environmental Matters:

• In March 2025, the EPA announced it expects to initiate a formal reconsideration of various environmental regulations and programs, including Clean Air Act Sections 111(b) and 111(d), the Cross-State Air Pollution Rule and Effluent Limitation Guidelines. 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 litigation.

Financings:

• Refer to “Results of Operations” for discussion of expected future issuances and retirements of long-term debt in 2025.

			24

Table of Contents

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 March 31 were as follows (dollars in millions, except per share amounts):

			2025												2024
			Income (Loss)						EPS						Income (Loss)						EPS
Utilities and Corporate Services			$225						$0.87						$159						$0.62
ATC Holdings			10						0.04						9						0.04
Non-utility and Parent			(22)						(0.08)						(10)						(0.04)
Alliant Energy Consolidated			$213						$0.83						$158						$0.62

Alliant Energy’s Utilities and Corporate Services net income increased by $66 million for the three-month period, primarily due to higher revenue requirements from IPL’s and WPL’s capital investments, estimated temperature impacts on retail electric and gas sales and the timing of income tax expense. These items were partially offset by higher depreciation and financing expenses.

Alliant Energy’s Non-utility and Parent net income decreased $12 million for the three-month period, primarily due to higher financing expense and the timing of income tax expense.

Net Income Variances - The following items contributed to increased (decreased) net income for the three months ended March 31, 2025 compared to the same period in 2024 (in millions):

			Alliant Energy						IPL						WPL
Revenues:
Changes in electric utility (Refer to details below)			$62						$38						$24
Changes in gas utility (Refer to details below)			35						10						25
Changes in other utility			—						(1)						1
Changes in total revenues			97						47						50
Operating expenses:
Changes in electric production fuel and purchased power (Refer to details below)			(12)						—						(12)
Changes in electric transmission service			(6)						(5)						(1)
Changes in cost of gas sold (Refer to details below)			(23)						(5)						(19)
Changes in other operation and maintenance			—						4						(4)
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)			(22)						(19)						(3)
Changes in taxes other than income taxes			1						1						—
Changes in total operating expenses			(62)						(24)						(39)
Changes in operating income			35						23						11
Other income and deductions:
Changes in interest expense (Higher primarily due to financings completed in 2024)			(12)						(5)						(2)
Changes in equity income from unconsolidated investments, net (Refer to Note 4 for details)			(2)						—						—
Changes in allowance for funds used during construction			(1)						(1)						—
Changes in Other			(2)						—						(2)
Changes in total other income and deductions			(17)						(6)						(4)
Changes in income before income taxes			18						17						7
Changes in income taxes (Refer to Note 8 for details)			37						30						11
Changes in net income			$55						$47						$18

			25

Table of Contents

Electric and Gas Revenues and Sales Summary - Electric and gas revenues (in millions), and megawatt-hour (MWh) and dekatherm (Dth) sales (in thousands), for the three months ended March 31 were as follows:

Alliant Energy			Electric																								Gas
			Revenues												MWhs Sold												Revenues												Dths Sold
			2025						2024						2025						2024						2025						2024						2025						2024
Retail			$773						$706						6,174						5,989						$224						$192						23,822						20,117
Sales for resale:
Wholesale			48						47						691						679						N/A						N/A						N/A						N/A
Bulk power and other			26						21						1,378						1,670						N/A						N/A						N/A						N/A
Transportation/Other			6						17						14						15						16						13						31,006						33,908
			$853						$791						8,257						8,353						$240						$205						54,828						54,025

IPL			Electric																								Gas
			Revenues												MWhs Sold												Revenues												Dths Sold
			2025						2024						2025						2024						2025						2024						2025						2024
Retail			$409						$376						3,439						3,365						$108						$101						11,772						10,205
Sales for resale:
Wholesale			14						13						182						182						N/A						N/A						N/A						N/A
Bulk power and other			1						(3)						396						324						N/A						N/A						N/A						N/A
Transportation/Other			6						6						8						8						10						7						12,071						11,695
			$430						$392						4,025						3,879						$118						$108						23,843						21,900

WPL			Electric																								Gas
			Revenues												MWhs Sold												Revenues												Dths Sold
			2025						2024						2025						2024						2025						2024						2025						2024
Retail			$364						$330						2,735						2,624						$116						$91						12,050						9,912
Sales for resale:
Wholesale			34						34						509						497						N/A						N/A						N/A						N/A
Bulk power and other			25						24						982						1,346						N/A						N/A						N/A						N/A
Transportation/Other			—						11						6						7						6						6						18,935						22,213
			$423						$399						4,232						4,474						$122						$97						30,985						32,125

Sales Trends and Temperatures - Alliant Energy’s retail electric sales volumes increased 3% for the three months ended March 31, 2025 compared to the same period in 2024, primarily due to changes in temperatures and increased sales volumes at WPL’s commercial and industrial customers. Alliant Energy’s retail gas sales volumes increased 18% for the three months ended March 31, 2025 compared to the same period in 2024, primarily due to changes in temperatures.

Estimated increases (decreases) to operating income from the impacts of temperatures for the three months ended March 31 were as follows (in millions):

			Electric																		Gas
			2025						2024						Change																								2025						2024						Change
IPL			($3)						($9)						$6																								($2)						($6)						$4
WPL			(3)						(10)						7																								(1)						(5)						4
Total Alliant Energy			($6)						($19)						$13																								($3)						($11)						$8

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.

			26

Table of Contents

Electric Utility Revenue Variances - The following items contributed to increased (decreased) electric utility revenues for the three months ended March 31, 2025 compared to the same period in 2024 (in millions):

																					Alliant Energy						IPL						WPL
Higher revenue requirements (a)(b)																					$108						$93						$15
Estimated changes in sales volumes caused by temperatures																					13						6						7
Higher revenues primarily due to changes in retail electric fuel-related costs (Refer to Electric Production Fuel and Purchased Power Expenses Variances below)																					12						—						12
Lower revenues at IPL due to credits on customers’ bills related to production tax credits through its fuel-related cost recovery mechanism (a)																					(51)						(51)						—
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)																					(17)						(17)						—
Changes in WPL electric fuel-related costs, net of recoveries (c)																					(5)						—						(5)
Other																					2						7						(5)
																					$62						$38						$24

(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)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 ($4) million and $1 million for the three months ended March 31, 2025 and 2024, respectively.

Gas Utility Revenue Variances - The following items contributed to increased (decreased) gas utility revenues for the three months ended March 31, 2025 compared to the same period in 2024 (in millions):

			Alliant Energy						IPL						WPL
Higher revenues due to changes in gas costs (Refer to Cost of Gas Sold Expense Variances below)			$24						$5						$19
Estimated changes in sales volumes caused by temperatures			8						4						4
Higher revenue requirements (a)			4						4						—
Other			(1)						(3)						2
			$35						$10						$25

(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 months ended March 31, 2025 compared to the same period in 2024 (in millions):

																					Alliant Energy						IPL						WPL
Lower (higher) purchased power expense (a)																					($14)						$2						($16)
Other																					2						(2)						4
																					($12)						$—						($12)

(a)Purchased power expense increased for the three months ended March 31, 2025 compared to the same period in 2024, primarily due to higher prices of electricity purchased at WPL.

			27

Table of Contents

Cost of Gas Sold Expense Variances - The following items contributed to (increased) decreased cost of gas sold expense for the three months ended March 31, 2025 compared to the same period in 2024 (in millions):

			Alliant Energy						IPL						WPL
Higher retail gas volumes			($12)						($5)						($7)
Changes in the regulatory recovery of gas costs			(12)						—						(12)
Other			1						—						—
			($23)						($5)						($19)

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** - In 2025 through 2028, Alliant Energy currently expects to issue up to $1.3 billion of common stock in aggregate through one or more equity offerings and up to $25 million of common stock annually through its Shareowner Direct Plan. For the remainder of 2025, IPL and WPL currently expect to issue up to $1.0 billion and $300 million, respectively, of long-term debt, and AEF and/or Alliant Energy at the parent company level expect to issue up to $1.3 billion of long-term debt in aggregate. IPL has $300 million of long-term debt maturing in 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 March 31, 2025, Alliant Energy had $25 million of cash and cash equivalents, $522 million ($193 million at the parent company, $141 million at IPL and $188 million at WPL) of available capacity under the single revolving credit facility and no available capacity at IPL under its sales of accounts receivable program.

Capital Structure - Financial capital structures at March 31, 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			249						307						59						76						190						241
Investing activities			(404)						(353)						(190)						(107)						(185)						(213)
Financing activities			99						18						114						(10)						(45)						(24)
Net increase (decrease)			(56)						(28)						(17)						(41)						(40)						4
Cash, cash equivalents and restricted cash, March 31			$25						$35						$12						$12						$11						$11

			28

Table of Contents

Operating Activities - The following items contributed to increased (decreased) operating activity cash flows for the three months ended March 31, 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			($51)						($51)						$—
Changes in interest payments			(42)						(26)						(7)
Lower collections from IPL’s retail customers due to credits on customers’ bills related to the tax benefit rider			(17)						(17)						—
Higher collections from IPL’s and WPL’s retail electric and IPL’s gas base rate increases			112						97						15
Increased collections from IPL’s and WPL’s retail customers caused by temperature impacts on electric and gas sales			21						10						11
Other (primarily due to other changes in working capital)			(81)						(30)						(70)
			($58)						($17)						($51)

Investing Activities - The following items contributed to increased (decreased) investing activity cash flows for the three months ended March 31, 2025 compared to the same period in 2024 (in millions):

			Alliant Energy						IPL						WPL
(Higher) lower utility construction and acquisition expenditures (a)			($76)						($123)						$47
Changes in the amount of cash receipts on sold receivables			37						37						—
Other			(12)						3						(19)
			($51)						($83)						$28

(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 impact of tariffs and the impact of 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

			29

Table of Contents

Financing Activities - The following items contributed to increased (decreased) financing activity cash flows for the three months ended March 31, 2025 compared to the same period in 2024 (in millions):

			Alliant Energy						IPL						WPL
Net changes in the amount of commercial paper outstanding			$361						$159						$347
Lower payments to retire long-term debt			300						—						—
Lower net proceeds from issuance of long-term debt			(597)						—						(297)
Higher common stock dividends			(7)						(39)						(26)
Lower capital contributions from IPL’s and WPL’s parent company, Alliant Energy			—						(5)						(55)
Other			24						9						10
			$81						$124						($21)

Common Stock Issuances - Refer to Note 5 for discussion of common stock issuances by Alliant Energy in 2025. Refer to “Results of Operations” for discussion of expected future issuances of common stock in 2025.

Long-term Debt - Refer to Note 6(b) for discussion of commercial paper classified as long-term debt and AEF’s term loan credit agreements. Refer to “Results of Operations” 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:

						Standard & Poor’s Ratings Services
Alliant Energy:			Corporate/issuer			BBB+
			Commercial paper			A-2
			Senior unsecured long-term debt			BBB
			Outlook			Stable
IPL:			Corporate/issuer			BBB+
			Commercial paper			A-2
			Senior unsecured long-term debt			BBB+
			Outlook			Stable
WPL:			Corporate/issuer			A-
			Commercial paper			A-2
			Senior unsecured long-term debt			A-
			Outlook			Stable

Off-Balance Sheet Arrangements and Certain Financial Commitments - A summary of Alliant Energy’s and IPL’s off-balance sheet arrangements and Alliant Energy’s, IPL’s and WPL’s contractual obligations is included in the 2024 Form 10-K and has not changed materially from the items reported in the 2024 Form 10-K, except for the items described in Notes 3, 6 and 12.