Alliant Energy 10-Q 2026-03-31

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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, 2026

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, 2026:

Alliant Energy Corporation, Common Stock, $0.01 par value, 258,277,037 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)

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TABLE OF CONTENTS

			Page
Definitions
Forward-looking Statements			1
Part I. Financial Information			4
Item 1. Condensed Consolidated Financial Statements (Unaudited)			4
Alliant Energy Corporation			4
Interstate Power and Light Company			7
Wisconsin Power and Light Company			10
Combined Notes to Condensed Consolidated Financial Statements			13
1. Summary of Significant Accounting Policies			13
2. Regulatory Matters			13
3. Receivables			13
4. Investments			14
5. Common Equity			14
6. Debt			17
7. Revenues			18
8. Income Taxes			18
9. Benefit Plans			19
10. Derivative Instruments			20
11. Fair Value Measurements			21
12. Commitments and Contingencies			22
13. Segments of Business			24
14. Related Parties			25
Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations			26
Item 3. Quantitative and Qualitative Disclosures About Market Risk			31
Item 4. Controls and Procedures			31
Part II. Other Information			31
Item 1. Legal Proceedings			32
Item 1A. Risk Factors			32
Item 2. Unregistered Sales of Equity Securities and Use of Proceeds			32
Item 5. Other Information			32
Item 6. Exhibits			33
Signatures			33

DEFINITIONS

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

Abbreviation or Acronym			Definition			Abbreviation or Acronym			Definition
2025 Form 10-K			Combined Annual Report on Form 10-K filed by Alliant Energy, IPL and WPL for the year ended Dec. 31, 2025			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
EPA			U.S. Environmental Protection Agency			Note(s)			Combined Notes to Condensed Consolidated Financial Statements
EPS			Earnings per weighted average common share			PSCW			Public Service Commission of Wisconsin
Financial Statements			Condensed Consolidated Financial Statements			SEC			Securities and Exchange Commission
FTR			Financial transmission right			U.S.			United States of America
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, recovery of and/or the return on costs, including fuel costs, operating costs, transmission costs, capacity costs, costs of cancelled generation projects incurred prior to pursuing regulatory approval, as well as costs of generation projects incurred prior to regulatory approval or 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 electric generating units (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 obtain regulatory approval for construction projects with acceptable conditions;

• the ability to complete construction of generation and energy storage projects by planned in-service dates, with the expected earnings contributions 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, including previously exempted tariffs related to solar project materials and equipment from certain countries, duties or other assessments, including antidumping or countervailing duties, inflation, labor issues or supply shortages, supply chain disruptions which may result from geopolitical issues, contractor performance, the ability to successfully resolve warranty issues or contract disputes, the ability to obtain adequate generator interconnection agreements to connect the new projects to MISO in a timely manner, the ability to obtain siting and environmental permits from local and state agencies and the ability of ITC Midwest LLC (ITC) and ATC to complete transmission upgrades 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 and other non-traditional service models, including alternative electric suppliers and potential policy changes, regulatory changes, or legislation that may enable large customers to source behind-the-meter generation directly from third parties or to own or otherwise procure on-site or behind-the-meter generation or participate in co-located resource arrangements, in IPL’s and WPL’s service territories on system reliability, operating expenses and customers’ demand for electricity;

• economic conditions in IPL’s and WPL’s service territories, including the potential impacts of business or facility closures and tariffs;

• the ability and cost to attract large load growth customers and to provide sufficient generation and the ability of ITC and ATC to provide sufficient transmission capacity for potential load growth timely, including significant new commercial or industrial customers, such as data centers;

• the ability of potential large load growth customers to timely construct new facilities, due to local or state regulatory actions, zoning, siting, or permitting actions, public or community opposition or other factors, as well as the resulting higher system load demand by expected levels and timeframes;

• the impact of large load growth customers altering, delaying or cancelling planned facilities, including any resulting impacts of overbuilt or under-utilized transmission capacity or generation and energy storage assets;

• 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 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 and/or financing 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, including any repeal, modification, or reduced funding of the Inflation Reduction Act and the One Big Beautiful Bill Act, and siting generation and energy storage projects;

• 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;

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• the impacts of changes in the tax code, including tax rates, minimum tax rates, adjustments made to deferred tax assets and liabilities, changes in state income tax apportionment, 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 risks associated with potential increases in borrowing costs or reduced access to funding, 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 interconnection or resource adequacy process establishing capacity planning reserve margin and capacity accreditation requirements that may impact how and when new and existing generating and energy storage facilities 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 to procure capacity in the market whereby such costs might not be recovered in rates;

• any legislative or regulatory changes that impose mandatory integrated resource planning requirements or materially modify existing planning processes, potentially affecting resource selection, cost recovery, and the ability to meet large load growth demand for energy;

• 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, siting requirements, 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 other postretirement benefits (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, including potential impairments;

• changes in technology that alter the channels through which customers buy or utilize Alliant Energy’s, IPL’s or WPL’s products and services;

• risks associated with third-party risk management practices, including vendor financial condition, operational performance, cybersecurity incidents, and compliance with contractual and regulatory requirements;

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• risks associated with large-scale internal technology modernization initiatives, including enterprise asset management systems, operational technology/informational technology integration, cloud transformation, and digital modernization, and the potential for delays, cost overruns, or operational impacts;

• 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 2025 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

ALLIANT ENERGY CORPORATION

CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED)

			For the Three Months
			Ended March 31,
			2026						2025
			(in millions, except per share amounts)
Revenues:
Electric utility			$888						$853
Gas utility			271						240
Other utility			2						13
Non-utility			23						22
Total revenues			1,184						1,128
Operating expenses:
Electric production fuel and purchased power			168						175
Electric transmission service			159						158
Cost of gas sold			173						137
Other operation and maintenance			180						160
Depreciation and amortization			223						211
Taxes other than income taxes			32						30
Total operating expenses			935						871
Operating income			249						257
Other (income) and deductions:
Interest expense			142						119
Equity income from unconsolidated investments, net			(22)						(13)
Allowance for funds used during construction			(30)						(18)
Other			(4)						3
Total other (income) and deductions			86						91
Income before income taxes			163						166
Income tax benefit			(61)						(47)
Net income attributable to Alliant Energy common shareowners			$224						$213
Weighted average number of common shares outstanding:
Basic			257.4						256.8
Diluted			258.8						257.2
Earnings per weighted average common share attributable to Alliant Energy common shareowners (basic and diluted)			$0.87						$0.83

Refer to accompanying Combined Notes to Condensed Consolidated Financial Statements.

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ALLIANT ENERGY CORPORATION

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED)

			March 31, 2026						December 31, 2025
			(in millions, except per share and share amounts)
ASSETS
Current assets:
Cash and cash equivalents			$115						$556
Accounts receivable, less allowance for expected credit losses			497						476
Production fuel, at weighted average cost			55						46
Gas stored underground, at weighted average cost			19						49
Materials and supplies, at weighted average cost			200						193
Regulatory assets			165						155
Other			173						222
Total current assets			1,224						1,697
Property, plant and equipment, net			20,589						20,344
Investments:
ATC Holdings			487						463
Other			237						231
Total investments			724						694
Other assets:
Regulatory assets			2,140						2,119
Deferred charges and other			136						137
Total other assets			2,276						2,256
Total assets			$24,813						$24,991

LIABILITIES AND EQUITY

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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 2025 Form 10-K. Unless otherwise noted, all “per share” references in MDA refer to earnings per diluted share.

2026 HIGHLIGHTS

Key highlights since the filing of the 2025 Form 10-K include the following:

Customer Investments:

• In March 2026, the IUC approved advance rate-making principles for IPL for up to 1,000 MW of new wind generation in Iowa. The rate-making principles approved include a fixed cost cap of $3,020/kilowatt, including AFUDC and transmission costs, among other costs. IPL’s return on common equity will be the same as other assets without advance rate-making principles for the purposes of setting future rates and IPL’s blended return on common equity, which will be updated each year, will be used for IPL’s retail electric earnings sharing mechanism calculation.

• In March 2026, WPL filed a certificate of authority application with the PSCW for approval to construct, own and install equipment that will maintain and increase the capacity and efficiency of its Riverside Energy Center. A decision from the PSCW is currently expected in the first quarter of 2027.

• In April 2026, IPL filed a certificate of public convenience, use and necessity application with the IUC for approval to construct, own and operate an approximately 720 MW simple-cycle natural gas-fired EGU in Linn County, Iowa. A decision from the IUC is currently expected in the first quarter of 2027.

Growing Customer Demand:

• In April 2026, IPL entered into an electric service agreement with a customer, who currently expects to build a data center in IPL’s service territory. This electric service agreement includes contracted peak demand of approximately 370 MW. The actual timing and amount of increases in IPL’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.

Environmental Matters:

Coal Combustion Residuals (CCR) Rule - In April 2026, the EPA proposed a rule that would significantly reduce the scope of the CCR Rule, which is currently anticipated to be finalized by the end of 2026. Alliant Energy, IPL and WPL continue to evaluate the revised CCR Rule and are unable to predict with certainty the future outcome or impact of these updates, including resolution of ongoing litigation.

Legislative Matters:

• In April 2026, the State of Wisconsin enacted 2025 Wisconsin Act 193, which requires utilities to include their capacity costs and revenues in their annual fuel cost plans. The most significant provisions of the legislation for Alliant Energy and WPL are the requirement that fuel cost calculations in approved fuel cost plans account for both the cost of purchasing capacity and the revenue generated from selling it. The legislation applies to fuel cost plans filed on or after January 1, 2027.

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 diluted EPS attributable to Alliant Energy common shareowners for the three months ended March 31 were as follows (dollars in millions, except per share amounts):

			2026												2025
			Income (Loss)						EPS						Income (Loss)						EPS
Utilities and Corporate Services			$215						$0.83						$225						$0.87
ATC Holdings			11						0.04						10						0.04
Non-utility and Parent			(2)						—						(22)						(0.08)
Alliant Energy Consolidated			$224						$0.87						$213						$0.83

Alliant Energy’s Utilities and Corporate Services net income decreased by $10 million for the three-month period, primarily due to higher other operation and maintenance, financing and depreciation expenses and the timing of income taxes. These items were partially offset by higher revenue requirements from IPL’s and WPL’s capital investments and higher AFUDC.

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Alliant Energy’s Non-utility and Parent net income increased $20 million for the three-month period, primarily due to a state income tax apportionment benefit (refer to Note 8 for details) and the timing of income taxes.

Net Income Variances - The following items contributed to increased (decreased) net income for the three months ended March 31, 2026 compared to the same period in 2025 (in millions):

			Alliant Energy						IPL						WPL
Revenues:
Changes in electric utility (Refer to details below)			$35						$7						$28
Changes in gas utility (Refer to details below)			31						4						27
Changes in other utility (Refer to Note 7 for details)			(11)						(10)						(1)
Changes in non-utility			1						—						—
Changes in total revenues			56						1						54
Operating expenses:
Changes in electric production fuel and purchased power (Refer to details below)			7						3						4
Changes in electric transmission service			(1)						4						(5)
Changes in cost of gas sold (Refer to details below)			(36)						(9)						(27)
Changes in other operation and maintenance (Refer to details below)			(20)						(5)						(15)
Changes in depreciation and amortization (Higher primarily due to energy storage placed in service in 2025)			(12)						(5)						(7)
Changes in taxes other than income taxes			(2)						—						(1)
Changes in total operating expenses			(64)						(12)						(51)
Changes in operating income			(8)						(11)						3
Other income and deductions:
Changes in interest expense (Higher primarily due to financings completed in 2025)			(23)						(10)						(5)
Changes in equity income from unconsolidated investments, net (Refer to Note 4 for details)			9						—						—
Changes in allowance for funds used during construction (Primarily due to changes in levels of construction work in progress balances related to energy storage and gas generation)			12						10						2
Changes in Other			7						3						4
Changes in total other income and deductions			5						3						1
Changes in income before income taxes			(3)						(8)						4
Changes in income taxes (Refer to Note 8 for details)			14						(8)						3
Changes in net income			$11						($16)						$7

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

Alliant Energy			Electric																								Gas
			Revenues												MWhs Sold												Revenues												Dths Sold
			2026						2025						2026						2025						2026						2025						2026						2025
Retail			$793						$773						6,137						6,174						$255						$224						22,486						23,822
Sales for resale:
Wholesale			35						48						511						691						N/A						N/A						N/A						N/A
Bulk power and other			51						26						1,626						1,378						N/A						N/A						N/A						N/A
Transportation/Other			9						6						13						14						16						16						32,813						31,006
			$888						$853						8,287						8,257						$271						$240						55,299						54,828

IPL			Electric																								Gas
			Revenues												MWhs Sold												Revenues												Dths Sold
			2026						2025						2026						2025						2026						2025						2026						2025
Retail			$425						$409						3,396						3,439						$113						$108						10,840						11,772
Sales for resale:
Wholesale			—						14						2						182						N/A						N/A						N/A						N/A
Bulk power and other			7						1						544						396						N/A						N/A						N/A						N/A
Transportation/Other			5						6						7						8						9						10						11,925						12,071
			$437						$430						3,949						4,025						$122						$118						22,765						23,843

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WPL			Electric																								Gas
			Revenues												MWhs Sold												Revenues												Dths Sold
			2026						2025						2026						2025						2026						2025						2026						2025
Retail			$368						$364						2,741						2,735						$142						$116						11,646						12,050
Sales for resale:
Wholesale			35						34						509						509						N/A						N/A						N/A						N/A
Bulk power and other			44						25						1,082						982						N/A						N/A						N/A						N/A
Transportation/Other			4						—						6						6						7						6						20,888						18,935
			$451						$423						4,338						4,232						$149						$122						32,534						30,985

Sales Trends and Temperatures - Alliant Energy’s retail electric sales volumes decreased 1% for the three months ended March 31, 2026, compared to the same period in 2025, primarily due to changes in temperatures. Alliant Energy’s retail gas sales volumes decreased 6% for the three months ended March 31, 2026, compared to the same period in 2025, 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
			2026						2025						Change																								2026						2025						Change
IPL			($7)						($3)						($4)																								($4)						($2)						($2)
WPL			(3)						(3)						—																								(2)						(1)						(1)
Total Alliant Energy			($10)						($6)						($4)																								($6)						($3)						($3)

Electric Sales for Resale - Alliant Energy’s and IPL’s wholesale sales volumes decreased for the three months ended March 31, 2026, compared to the same period in 2025, primarily due to the expiration of IPL’s wholesale power agreement with Southern Minnesota Energy Cooperative in 2025.

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 months ended March 31, 2026 compared to the same period in 2025 (in millions):

																					Alliant Energy						IPL						WPL
Higher revenue requirements (a)																					$26						$—						$26
Higher sales for resale bulk power and other revenues (b)																					25						6						19
Higher revenues at IPL due to credits on customers’ bills through the tax benefit rider in 2025 (partially offset by changes in wholesale revenues and income taxes)																					17						17						—
Lower revenues primarily due to changes in retail electric fuel-related costs (Refer to Electric Production Fuel and Purchased Power Expenses Variances below) (a)																					(17)						(6)						(11)
Lower wholesale revenues at IPL primarily due to lower sales from the expiration of IPL’s wholesale power agreement with Southern Minnesota Energy Cooperative in 2025																					(14)						(14)						—
Changes in WPL refunds/collections of previous over-/under-collection of retail electric fuel-related costs (offset in electric production fuel and purchased power expenses)																					(13)						—						(13)
Estimated changes in sales volumes caused by temperatures																					(4)						(4)						—
Other																					15						8						7
																					$35						$7						$28

(a)In December 2025, the PSCW issued an order authorizing an annual base rate increase of $69 million for WPL’s retail electric customers, covering the 2026 forward-looking Test Period, which reflects revenue requirement impacts of increasing electric rate base, including wind refurbishment projects, energy storage, existing natural gas-fired EGU improvements and electric distribution investments and lower forecasted fuel-related expenses.

(b)Sales for resale bulk power and other revenues increased primarily due to higher volumes and higher prices for electricity sold by IPL and WPL to MISO wholesale energy markets. These changes were largely offset by changes in fuel-related costs.

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Gas Utility Revenue Variances - The following items contributed to increased (decreased) gas utility revenues for the three months ended March 31, 2026 compared to the same period in 2025 (in millions):

			Alliant Energy						IPL						WPL
Higher revenues due to changes in gas costs (Refer to Cost of Gas Sold Expense Variances below)			$35						$9						$26
Higher revenue requirements (a)			2						—						2
Estimated changes in sales volumes caused by temperatures			(3)						(2)						(1)
Other			(3)						(3)						—
			$31						$4						$27

(a)In December 2025, the PSCW issued an order authorizing an annual base rate increase of $7 million for WPL’s retail gas customers, covering the 2026 forward-looking Test Period, which reflects 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, 2026 compared to the same period in 2025 (in millions):

																					Alliant Energy						IPL						WPL
Lower purchased power expense (a)																					$16						$13						$3
Changes in regulatory recovery of retail electric fuel-related costs																					13						1						12
Changes in WPL refunds/collections of previous over-/under-collection of retail electric fuel-related costs (offset in electric utility revenue)																					13						—						13
Higher electric production fuel costs (b)																					(34)						(11)						(23)
Other																					(1)						—						(1)
																					$7						$3						$4

(a)Purchased power expense decreased for the three months ended March 31, 2026 compared to the same period in 2025, primarily due to lower prices for electricity purchased and lower volumes purchased at IPL and WPL.

(b)Electric production fuel costs increased for the three months ended March 31, 2026 compared to the same period in 2025, primarily due to higher natural gas volumes due to higher dispatch of natural gas-fired EGUs and higher natural gas prices.

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, 2026 compared to the same period in 2025 (in millions):

			Alliant Energy						IPL						WPL
Changes in retail gas volumes and natural gas prices			($46)						($21)						($25)
Changes in the regulatory recovery of gas costs			11						12						(1)
Other			(1)						—						(1)
			($36)						($9)						($27)

Other Operation and Maintenance Expenses Variances - The following items contributed to (increased) decreased other operation and maintenance expenses for the three months ended March 31, 2026 compared to the same period in 2025 (in millions):

			Alliant Energy						IPL						WPL
Higher generation and energy delivery expenses			($18)						($7)						($11)
Other			(2)						2						(4)
			($20)						($5)						($15)

LIQUIDITY AND CAPITAL RESOURCES

The liquidity and capital resources summary included in the 2025 Form 10-K has not changed materially, except as described below.

Liquidity Position - At March 31, 2026, Alliant Energy had $115 million of cash and cash equivalents, $817 million ($268 million at the parent company, $249 million at IPL and $300 million at WPL) of available capacity under the single revolving credit facility and $40 million of available capacity at IPL under its sales of accounts receivable program.

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Capital Structure - The following table shows financial capital structures as of March 31, 2026, as well as an adjusted capitalization structure that Alliant Energy believes is consistent with how a majority of the rating agencies currently view its junior subordinated notes (in millions):

			Alliant Energy												IPL						WPL
			Actual						Adjusted (a)						Actual						Actual
Common equity			$7,422						$7,785						$5,023						$4,462
Long-term debt (including current maturities)			11,007						10,644						4,731						3,670
Short-term debt			833						833						1						—
Total capitalization			$19,262						$19,262						$9,755						$8,132
Total debt			$11,840						$11,477						$4,732						$3,670
Ratio of debt to total capitalization			61		%				60		%				49		%				45		%

(a)The long-term debt component of Alliant Energy’s financial capital structure includes junior subordinated notes classified as “Long-term debt, net” on Alliant Energy’s balance sheet. The adjusted presentation attributes 50% of the junior subordinated notes to common equity and 50% to long-term debt, to align with the debt-to-capital ratio used by the majority of rating agencies. The non-GAAP adjusted presentation reflecting this treatment is useful and relevant to investors in understanding how management and the rating agencies evaluate Alliant Energy’s capital structure.

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

			Alliant Energy												IPL												WPL
			2026						2025						2026						2025						2026						2025
Cash, cash equivalents and restricted cash, January 1			$556						$81						$7						$29						$37						$51
Cash flows from (used for):
Operating activities			368						249						136						59						239						190
Investing activities			(393)						(404)						(179)						(190)						(149)						(185)
Financing activities			(416)						99						48						114						(28)						(45)
Net increase (decrease)			(441)						(56)						5						(17)						62						(40)
Cash, cash equivalents and restricted cash, March 31			$115						$25						$12						$12						$99						$11

Operating Activities - The following items contributed to increased (decreased) operating activity cash flows for the three months ended March 31, 2026 compared to the same period in 2025 (in millions):

			Alliant Energy						IPL						WPL
Changes in income taxes paid/received (a)			$90						$47						$43
Higher collections from WPL’s retail electric and gas base rate increases			28						—						28
Higher collections from IPL’s retail customers due to credits on customers’ bills related to the tax benefit rider in 2025			17						17						—
Timing of WPL’s fuel-related cost recoveries from retail electric customers			(25)						—						(25)
Other (primarily due to other changes in working capital)			9						13						3
			$119						$77						$49

(a)Refer to the cash flows statements for details of renewable tax credits transferred to other corporate taxpayers during the three months ended March 31, 2026.

Investing Activities - The following items contributed to increased (decreased) investing activity cash flows for the three months ended March 31, 2026 compared to the same period in 2025 (in millions):

			Alliant Energy						IPL						WPL
Lower utility construction and acquisition expenditures (a)			$212						$178						$34
Changes in the amount of cash receipts on sold receivables			(167)						(167)						—
Higher non-utility construction and acquisition expenditures			(44)						—						—
Other			10						—						2
			$11						$11						$36

(a)Largely due to lower expenditures for IPL’s energy storage and WPL’s gas generation.

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Financing Activities - The following items contributed to increased (decreased) financing activity cash flows for the three months ended March 31, 2026 compared to the same period in 2025 (in millions):

			Alliant Energy						IPL						WPL
Higher payments to retire long-term debt			($1,075)						$—						$—
(Higher) lower common stock dividends			(7)						49						20
Higher capital contributions from IPL’s and WPL’s parent company, Alliant Energy			—						80						25
Higher proceeds from issuance of other short-term borrowings			400						—						—
Net changes in the amount of commercial paper outstanding			175						(196)						(29)
Other			(8)						1						1
			($515)						($66)						$17

Common Stock Issuances - Refer to Note 5 for discussion of common stock issuances by Alliant Energy in 2026 and Alliant Energy’s at-the-market offering programs.

Short-term Debt - Refer to Note 6(a) for discussion of Alliant Energy’s term loan credit agreement entered into in 2026.

Long-term Debt - Refer to Note 6(b) for discussion of issuances and/or retirements of long-term debt by Alliant Energy, AEF and IPL in 2026.

Impact of Credit Ratings on Liquidity and Collateral Obligations -

Ratings Triggers - In March 2026, Standard & Poor’s Ratings Services changed certain IPL credit ratings, which are not expected to have a material impact on Alliant Energy’s and IPL’s liquidity or collateral obligations. Alliant Energy’s, IPL’s and WPL’s 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			A-
			Commercial paper			A-2
			Senior unsecured long-term debt			A-
			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 2025 Form 10-K and has not changed materially from the items reported in the 2025 Form 10-K, except for the items described in Notes 3, 6 and 12.