Financial Analysis

COMMITMENTS AND CONTINGENCIES(a) Capital Purchase Commitments - Various contractual obligations contain minimum future commitments related to capital expenditures for certain construction projects, including IPLs and WPLs expansion of energy storage, improvements at the natural gas-fired Neenah Energy Facility and Sheboygan Falls Energy Facility, and repowering projects at WPLs Bent Tree Energy Facility. At December 31, 2025, Alliant Energys, IPLs, and WPLs minimum future commitments in 2026 for these projects were $459 million, $302 million, and $155 million, respectively. (b) Other Purchase Commitments - Various commodity supply, transportation and storage contracts help meet obligations to provide electricity and natural gas to utility customers. In addition, there are various purchase commitments associated with other goods and services. At December 31, 2025, the related minimum future commitments, excluding amounts for purchased power commitments that do not have minimum thresholds but require payment when electricity is generated by the provider and amounts for future commitments to deliver power to electric customers that do not have current minimum thresholds but will be billed for requirements when power is provided, were as follows (in millions): Alliant Energy 2026 2027 2028 2029 2030 Thereafter Total Natural gas $271 $191 $163 $145 $103 $245 $1,118 Coal 76 42 28 146 Other (a) 57 16 8 4 3 17 105 $404 $249 $199 $149 $106 $262 $1,369 IPL 2026 2027 2028 2029 2030 Ther …

CommitmentsAndContingenciesDisclosureTextBlock · excerpt; the full note is in the filing

BENEFIT PLANS(a) Pension and Other Postretirement Benefits Plans - Retirement benefits are provided to substantially all employees through various qualified and non-qualified non-contributory defined benefit pension plans (currently closed to new hires), and/or through defined contribution plans (including 401(k) savings plans). Benefits of the non-contributory defined benefit pension plans are based on the plan participants years of service, age and compensation. Benefits of the defined contribution plans are based on the plan participants years of service, age, compensation and contributions. Certain defined benefit postretirement health care and life benefits are provided to eligible retirees. In general, the retiree health care plans consist of fixed benefit subsidy structures and the retiree life insurance plans are non-contributory. IPL and WPL account for their participation in Alliant Energy and Corporate Services sponsored plans as multiple-employer plans. For IPL and WPL, amounts below represent the amounts for their plan participants covered under plans they sponsor, as well as amounts directly assigned to them related to certain participants in the Alliant Energy and Corporate Services sponsored plans. Assumptions - The weighted-average assumptions for defined benefit pension and OPEB plans at the measurement date of December 31 were as follows: Defined Benefit Pension Plans OPEB Plans Alliant Energy 2025 2024 2023 2025 2024 2023 Discount rate for benefit obligati …

CompensationAndEmployeeBenefitPlansTextBlock · excerpt; the full note is in the filing

DEBT(a) Short-term Debt - Alliant Energy and its subsidiaries maintain committed bank lines of credit to provide short-term borrowing flexibility and back-stop liquidity for commercial paper outstanding. At December 31, 2025, the short-term borrowing capacity under a single credit facility agreement, which expires in December 2030, totaled $1.3 billion ($550 million for Alliant Energy at the parent company level, $350 million for IPL and $400 million for WPL). Subject to certain conditions, Alliant Energy (at the parent company level), IPL and WPL may each reallocate and change its sublimit up to $1 billion, $400 million and $500 million, respectively, within the $1.3 billion total commitment. Information regarding Alliant Energys, IPLs and WPLs commercial paper and borrowings under the single credit facility classified as short-term debt was as follows (dollars in millions): Alliant Energy IPL WPL December 31 2025 2024 2025 2024 2025 2024 Amount outstanding $88 $558 $88 $50 $ $183 Weighted average interest rates 3.8% 4.5% 3.8% 4.6% N/A 4.5% Available credit facility capacity $1,212 $742 $262 $250 $400 $217 Alliant Energy IPL WPL For the year ended 2025 2024 2025 2024 2025 2024 Maximum amount outstanding (based on daily outstanding balances) $741 $632 $141 $80 $297 $390 Average amount outstanding (based on daily outstanding balances) $349 $327 $25 $1 $176 $70 Weighted average interest rates 4.5% 5.3% 4.6% 5.1% 4.5% 5.4% (b) Long-Term Debt - Long-term debt, net as of December …

DebtDisclosureTextBlock · excerpt; the full note is in the filing

Disaggregation of revenues from contracts with customers is provided for each reportable segment (IPL and WPL), as well as by customer class within electric and gas sales, as follows (in millions): Alliant Energy IPL WPL 2025 2024 2023 2025 2024 2023 2025 2024 2023 Electric Utility: Retail - residential $1,339 $1,236 $1,220 $661 $640 $641 $678 $596 $579 Retail - commercial 932 821 820 609 525 519 323 296 301 Retail - industrial 1,034 952 968 531 497 501 503 455 467 Wholesale 184 200 213 39 61 62 145 139 151 Bulk power and other 208 163 124 56 24 38 152 139 86 Total Electric Utility 3,697 3,372 3,345 1,896 1,747 1,761 1,801 1,625 1,584 Gas Utility: Retail - residential 306 275 316 155 148 176 151 127 140 Retail - commercial 153 133 163 72 68 86 81 65 77 Retail - industrial 13 11 16 7 7 11 6 4 5 Transportation/other 53 46 45 31 27 27 22 19 18 Total Gas Utility 525 465 540 265 250 300 260 215 240 Other Utility: Steam 37 40 45 37 40 45 Other utility 14 14 7 10 9 4 4 5 3 Total Other Utility 51 54 52 47 49 49 4 5 3 Non-Utility and Other: Travero and other 89 90 90 Total Non-Utility and Other 89 90 90 Total revenues $4,362 $3,981 $4,027 $2,208 $2,046 $2,110 $2,065 $1,845 $1,827 …

DisaggregationOfRevenueTableTextBlock · excerpt; the full note is in the filing

FAIR VALUE MEASUREMENTS Valuation Hierarchy - Fair value measurement accounting establishes three levels of fair value hierarchy that prioritize the inputs to valuation techniques used to measure fair value. Level 1 pricing inputs are quoted prices available in active markets for identical assets or liabilities as of the reporting date. Level 2 pricing inputs are quoted prices for similar assets or liabilities in active markets or quoted prices for identical or similar assets or liabilities in markets that are not active as of the reporting date. Level 3 pricing inputs are unobservable inputs for assets or liabilities for which little or no market data exist and require significant management judgment or estimation. The fair value hierarchy gives the highest priority to quoted prices in active markets (Level 1) and the lowest priority to unobservable data (Level 3). In some cases, the inputs used to measure fair value might fall in different levels of the fair value hierarchy. The lowest level input that is significant to a fair value measurement in its entirety determines the applicable level in the fair value hierarchy. Assessing the significance of a particular input to the fair value measurement in its entirety requires judgment, considering factors specific to the asset or liability. Valuation Techniques - Derivative assets and derivative liabilities - Swap, option and physical forward commodity contracts were non-exchange-based derivative instruments and were valued usi …

FairValueDisclosuresTextBlock · excerpt; the full note is in the filing

INCOME TAXES Income Tax Expense (Benefit) - The components of Income tax expense (benefit) in the income statements were as follows (in millions): Alliant Energy IPL WPL 2025 2024 2023 2025 2024 2023 2025 2024 2023 Current tax expense (benefit): Federal $10 $13 ($3) ($21) ($19) ($44) $38 $37 $48 State (1) (10) (6) (10) (19) (21) 18 23 25 Deferred tax expense (benefit): Federal 59 60 100 36 38 87 30 24 10 State 33 15 36 2 (17) 17 16 7 3 Production tax credits (208) (177) (121) (133) (108) (95) (75) (69) (26) Investment tax credits (42) (15) (1) (1) (4) (1) (41) (11) Provision recorded as a change in accrued interest (1) (1) ($149) ($114) $4 ($127) ($129) ($58) ($14) $11 $60 Income Tax Rates - The overall income tax rates shown in the following table were computed by dividing income tax expense (benefit) by income before income taxes. In 2024, Alliant Energys and IPLs effective income tax rates were impacted by the pre-tax non-cash charge of $60 million for IPLs Lansing Generating Station discussed in Note 2 . In the fourth quarter of 2025, Alliant Energy, IPL and WPL retrospectively adopted the Financial Accounting Standards Boards (FASB) accounting standard for improvements to income tax disclosures. Previously reported information for prior periods has been recast to conform with current period presentation. Alliant Energy 2025 2024 2023 Amount Tax Rate Amount Tax Rate Amount Tax Rate Statutory federal income tax rate $139 21% $121 21% $149 21% State income taxes, net of fed …

IncomeTaxDisclosureTextBlock · excerpt; the full note is in the filing

LEASES Operating Leases - Alliant Energys, IPLs and WPLs operating leases primarily include leases of space on telecommunication towers and leases of property. Operating lease details are as follows (dollars in millions): December 31, 2025 December 31, 2024 Alliant Energy IPL WPL Alliant Energy IPL WPL Property, plant and equipment, net $21 $11 $9 $22 $12 $9 Other current liabilities $2 $1 $1 $2 $1 $1 Other liabilities 19 10 8 20 11 8 Total operating lease liabilities $21 $11 $9 $22 $12 $9 Weighted average remaining lease term 10 years 10 years 11 years 11 years 11 years 12 years Weighted average discount rate 4% 4% 4% 4% 4% 4% Finance Leases - WPL is currently leasing the Sheboygan Falls Energy Facility from AEFs Non-utility Generation business. WPL is responsible for the operation of the EGU and has exclusive rights to its output. In 2024, WPL renewed this financing lease through 2044. There are no lease renewal periods remaining. In 2025, WPLs rent payments increased following the completion of certain enhancements to the Sheboygan Falls Energy Facility, resulting in a lease modification and remeasurement. For Alliant Energy, the leased Sheboygan Falls Energy Facility is eliminated upon consolidation and therefore is not reflected in Alliant Energys amounts below. Related to their investments in solar generation, IPL and WPL entered into various land lease agreements with unaffiliated parties that have commenced. The leases have various terms with optional renewal periods …

LesseeOperatingLeasesTextBlock · excerpt; the full note is in the filing

RELATED PARTIES Service Agreements - Pursuant to service agreements, IPL and WPL receive various administrative and general services from an affiliate, Corporate Services. These services are billed to IPL and WPL at cost based on expenses incurred by Corporate Services for the benefit of IPL and WPL, respectively. These costs consisted primarily of employee compensation and benefits, fees associated with various professional services, depreciation and amortization of property, plant and equipment, and a return on net assets. Corporate Services also acts as agent on behalf of IPL and WPL pursuant to the service agreements. As agent, Corporate Services enters into energy, capacity, ancillary services, and transmission sale and purchase transactions within MISO. Corporate Services assigns such sales and purchases among IPL and WPL based on statements received from MISO. The amounts billed for services provided, sales credited and purchases were as follows (in millions): IPL WPL 2025 2024 2023 2025 2024 2023 Corporate Services billings $194 $183 $181 $189 $171 $163 Sales credited 27 11 131 84 55 Purchases billed 416 430 431 75 54 35 As of December 31, net intercompany payables to Corporate Services were as follows (in millions): 2025 2024 IPL $135 $135 WPL 84 64 ATC - Pursuant to various agreements, WPL receives a range of transmission services from ATC. WPL provides operation, maintenance, and construction services to ATC. WPL and ATC also bill each other for use of shared facil …

RelatedPartyTransactionsDisclosureTextBlock · excerpt; the full note is in the filing

REVENUES Revenues from Alliant Energys, IPLs and WPLs utility businesses are primarily from electric and gas sales provided to customers based on approved tariffs or specific contracts with customers. IPLs and WPLs primary performance obligations under such arrangements are to deliver electricity and gas, and their customers simultaneously receive and consume the electricity and gas. For such arrangements, revenues are recognized equivalent to the value of the electricity or gas supplied during each period, including amounts billed during each period and changes in amounts estimated to be billed at the end of each period. IPL and WPL apply the right to invoice method to measure progress towards completing performance obligations to transfer electricity and gas to their customers. IPL provides retail electric and gas service to customers in Iowa, and WPL provides retail and wholesale electric and retail gas service to customers in Wisconsin. IPL also provides electricity to wholesale customers in Illinois and Iowa. IPLs wholesale power agreement with Southern Minnesota Energy Cooperative expired in July 2025. IPL provided steam from its Prairie Creek Generating Station to high-pressure steam customers in Iowa through 2025. IPLs and WPLs retail electric and gas revenues include sales to residential, commercial and industrial customers. IPLs and WPLs retail electric and gas customer prices are based on IPLs and WPLs cost of service and are determined through general rate review …

RevenueFromContractWithCustomerTextBlock · excerpt; the full note is in the filing

SEGMENTS OF BUSINESS Alliant Energy - Alliant Energys two reportable segments as of December 31, 2025 are: IPL - is a utility primarily serving electric and natural gas customers in Iowa, and is its own reportable segment as shown in the tables below. WPL - is a utility serving electric and natural gas customers in Wisconsin, and is its own reportable segment as shown in the tables below. Other, which is not a reportable segment of Alliant Energy, includes the operations of AEF and its subsidiaries, Corporate Services, the Alliant Energy parent company, and any Alliant Energy parent company consolidating adjustments. AEF is comprised of Alliant Energys interest in ATC Holdings, Travero, a non-utility wind farm, corporate venture investments, the Sheboygan Falls Energy Facility and other non-utility holdings. The Other columns are included in the tables below to reconcile to consolidated amounts. Prior to December 31, 2024, reportable segments for Alliant Energys, IPLs, and WPLs utility business were electric operations, gas operations, and other. In the fourth quarter of 2024, Alliant Energy, IPL and WPL adopted the FASBs accounting standard for improvements to reportable segment disclosures. Previously reported information for prior periods has been recast to conform with the current period presentation. Alliant Energys chief operating decision maker (CODM) is its President and CEO, and IPLs and WPLs CODM is their CEO. The CODM uses net income generated from IPLs and WPLs op …

SegmentReportingDisclosureTextBlock · excerpt; the full note is in the filing

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES(a) General - Description of Business - Alliant Energys financial statements include the accounts of Alliant Energy and its consolidated subsidiaries. Alliant Energy is a Midwest U.S. energy holding company, whose primary wholly-owned subsidiaries are IPL, WPL, AEF and Corporate Services. IPLs financial statements include the accounts of IPL and its consolidated subsidiaries, including IPL SPE LLC, which is used for IPLs sales of accounts receivable program. IPL is a direct subsidiary of Alliant Energy and is a public utility engaged principally in the generation and distribution of electricity and the distribution and transportation of natural gas to retail customers in select markets in Iowa. IPL also sells electricity to wholesale customers in Illinois and Iowa. In July 2025, IPLs wholesale power agreement with Southern Minnesota Energy Cooperative expired. IPL provided steam from its Prairie Creek Generating Station to high-pressure steam customers in Cedar Rapids, Iowa through 2025. WPLs financial statements include the accounts of WPL and its consolidated subsidiaries. WPL is a direct subsidiary of Alliant Energy and is a public utility engaged principally in the generation and distribution of electricity and the distribution and transportation of natural gas to retail customers in select markets in Wisconsin. WPL also sells electricity to wholesale customers in Wisconsin. AEF is comprised of Travero, ATI, corporate venture inve …

SignificantAccountingPoliciesTextBlock · excerpt; the full note is in the filing

COMMON EQUITY Common Share Activity - A summary of Alliant Energys common stock activity was as follows: 2025 2024 2023 Shares outstanding, January 1 256,690,222 256,096,848 251,134,966 At-the-market offering program 4,372,561 Shareowner Direct Plan 360,662 439,107 454,987 Equity-based compensation plans 86,377 154,267 134,334 Shares outstanding, December 31 257,137,261 256,690,222 256,096,848 At December 31, 2025, Alliant Energy had a total of 11 million shares available for issuance in the aggregate, pursuant to its 2020 OIP, Shareowner Direct Plan and 401(k) Savings Plan. At-the-Market Offering Program - In December 2022, Alliant Energy filed a prospectus supplement to sell up to $225 million of its common stock through an at-the-market offering program. In 2023, Alliant Energy issued 4,372,561 shares of common stock through this program and received cash proceeds of $223 million, net of $2 million in commissions and fees. The proceeds from the issuances of common stock were used for general corporate purposes. This at-the-market offering program has expired. In May 2025, Alliant Energy filed a prospectus supplement and executed a related distribution agreement, under which it may sell up to $1.3 billion in aggregate of its common stock through 2028 through an at-the-market offering program that includes an equity forward sales component. Alliant Energy expects to use proceeds from the issuance of common stock for general corporate purposes. Alliant Energy entered into for …

StockholdersEquityNoteDisclosureTextBlock · excerpt; the full note is in the filing

COMMITMENTS AND CONTINGENCIES NOTE 12(a) Capital Purchase Commitments - Various contractual obligations contain minimum future commitments related to capital expenditures for certain construction projects, including expansion of IPLs gas generation, IPLs and WPLs expansion of energy storage and repowering projects at WPLs Bent Tree Energy Facility. At June 30, 2026, Alliant Energys, IPLs and WPLs minimum future commitments for these projects were $278 million, $171 million and $106 million, respectively. Tariff-Related Costs - In February 2026, the Supreme Court ruled that the International Emergency Economic Powers Act (IEEPA) does not provide the Executive Branch of the U.S. government with authority to impose tariffs, and, in March 2026, the Court of International Trade ordered Customs and Border Protection to refund IEEPA tariffs previously collected. Certain third-party suppliers engaged by IPL and WPL act as importers of record and may be eligible for refunds of tariffs previously paid. Alliant Energy, IPL and WPL are currently evaluating the potential recovery of tariff-related costs, which could reduce amounts previously capitalized as part of the construction of generation and energy storage facilities. Due to uncertainty regarding the eligibility, timing and amount of tariff-related cost recoveries, Alliant Energy, IPL and WPL concluded that recovery is not probable and therefore have not recognized any amounts related to potential tariff cost recoveries as of June …

CommitmentsAndContingenciesDisclosureTextBlock · excerpt; the full note is in the filing

BENEFIT PLANS NOTE 9(a) Pension and OPEB Plans - Net Periodic Benefit Costs - The components of net periodic benefit costs for sponsored defined benefit pension and OPEB plans for the three and six months ended June 30 are included below (in millions). For IPL and WPL, amounts are for their plan participants covered under plans they sponsor, as well as amounts directly assigned to them related to certain participants in the Alliant Energy and Corporate Services sponsored plans. Defined Benefit Pension Plans OPEB Plans Three Months Six Months Three Months Six Months Alliant Energy 2026 2025 2026 2025 2026 2025 2026 2025 Service cost $1 $1 $2 $2 $ $1 $ $1 Interest cost 11 12 22 23 2 2 4 4 Expected return on plan assets (14) (14) (28) (27) (1) (2) (2) (3) Amortization of actuarial loss 5 5 9 11 $3 $4 $5 $9 $1 $1 $2 $2 Defined Benefit Pension Plans OPEB Plans Three Months Six Months Three Months Six Months IPL 2026 2025 2026 2025 2026 2025 2026 2025 Service cost $1 $ $1 $1 $ $ $ $ Interest cost 5 5 10 10 1 1 2 2 Expected return on plan assets (6) (6) (12) (12) (1) (1) (2) (2) Amortization of actuarial loss 1 2 3 4 $1 $1 $2 $3 $ $ $ $ Defined Benefit Pension Plans OPEB Plans Three Months Six Months Three Months Six Months WPL 2026 2025 2026 2025 2026 2025 2026 2025 Service cost $ $1 $ $1 $ $ $ $ Interest cost 5 5 10 10 1 1 Expected return on plan assets (6) (6) (12) (12) Amortization of actuarial loss 2 2 4 5 $1 $2 $2 $4 $ $ $1 $1 (b) Equity-based Compensation Plans - A summary of …

CompensationAndEmployeeBenefitPlansTextBlock · excerpt; the full note is in the filing

DEBT NOTE 6(a) Short-term Debt - In March 2026, Alliant Energy, IPL and WPL reallocated credit facility capacity amounts to $700 million for Alliant Energy at the parent company level, $300 million for IPL and $300 million for WPL, within the $1.3 billion total commitment. Information regarding Alliant Energys, IPLs and WPLs commercial paper and borrowings under the single credit facility classified as short-term debt was as follows (dollars in millions): June 30, 2026 Alliant Energy IPL WPL Amount outstanding $708 $77 $83 Weighted average interest rates 3.9% 3.9% 3.9% Available credit facility capacity (a) $542 $173 $217 Alliant Energy IPL WPL Three Months Ended June 30 2026 2025 2026 2025 2026 2025 Maximum amount outstanding (based on daily outstanding balances) $732 $741 $77 $141 $110 $292 Average amount outstanding (based on daily outstanding balances) $569 $449 $12 $33 $47 $225 Weighted average interest rates 3.9% 4.6% 3.9% 4.6% 3.9% 4.6% Six Months Ended June 30 Maximum amount outstanding (based on daily outstanding balances) $732 $741 $103 $141 $110 $292 Average amount outstanding (based on daily outstanding balances) $347 $495 $29 $43 $24 $193 Weighted average interest rates 3.9% 4.6% 3.8% 4.6% 3.9% 4.6% (a) Alliant Energys and IPLs available credit facility capacities reflect outstanding commercial paper classified as both short- and long-term debt at June 30, 2026. In March 2026, Alliant Energy entered into a $400 million variable rate (4.5% as of June 30, 2026) ter …

DebtDisclosureTextBlock · excerpt; the full note is in the filing

Disaggregation of revenues from contracts with customers is provided for each reportable segment (IPL and WPL), as well as by customer class within electric and gas sales, as follows (in millions): Alliant Energy IPL WPL Three Months Ended June 30 2026 2025 2026 2025 2026 2025 Electric Utility: Retail - residential $309 $295 $151 $142 $158 $153 Retail - commercial 221 211 143 135 78 76 Retail - industrial 251 240 126 118 125 122 Wholesale 36 49 14 36 35 Bulk power and other 44 56 11 9 33 47 Total Electric Utility 861 851 431 418 430 433 Gas Utility: Retail - residential 44 41 23 21 21 20 Retail - commercial 25 20 13 10 12 10 Retail - industrial 3 3 2 2 1 1 Transportation/other 10 12 5 7 5 5 Total Gas Utility 82 76 43 40 39 36 Other Utility: Steam (a) 9 9 Other utility 2 2 1 2 1 Total Other Utility 2 11 1 11 1 Non-Utility and Other: Travero and other 26 23 Total Non-Utility and Other 26 23 Total revenues $971 $961 $475 $469 $470 $469 Alliant Energy IPL WPL Six Months Ended June 30 2026 2025 2026 2025 2026 2025 Electric Utility: Retail - residential $641 $618 $311 $297 $330 $321 Retail - commercial 442 425 285 271 157 154 Retail - industrial 491 475 249 236 242 239 Wholesale 71 97 28 71 69 Bulk power and other 103 88 22 16 81 72 Total Electric Utility 1,748 1,703 867 848 881 855 Gas Utility: Retail - residential 206 188 99 95 107 93 Retail - commercial 111 94 48 43 63 51 Retail - industrial 9 8 4 4 5 4 Transportation/other 27 26 15 16 12 10 Total Gas Utility 353 316 166 158 187 …

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FAIR VALUE MEASUREMENTS Fair Value of Financial Instruments - The carrying amounts of current assets and current liabilities approximate fair value because of the short maturity of such financial instruments. Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions): Alliant Energy June 30, 2026 December 31, 2025 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Money market fund investments $ $ $ $ $ $411 $411 $ $ $411 Commodity derivatives 121 18 103 121 69 36 33 69 Interest rate derivatives 4 4 4 1 1 1 Deferred proceeds 95 95 95 126 126 126 Liabilities: Commodity derivatives 71 71 71 51 50 1 51 Long-term debt (incl. current maturities) 11,010 10,650 10,650 12,028 11,748 11,748 IPL June 30, 2026 December 31, 2025 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Commodity derivatives $85 $ $10 $75 $85 $44 $ $18 $26 $44 Deferred proceeds 95 95 95 126 126 126 Liabilities: Commodity derivatives 21 21 21 11 10 1 11 Long-term debt 4,732 4,456 4,456 4,680 4,445 4,445 WPL June 30, 2026 December 31, 2025 Fair Value Fair Value Carrying Level Level Level Carrying Level Level Level Amount 1 2 3 Total Amount 1 2 3 Total Assets: Money market fund investments $ $ $ $ $ $25 $25 $ $ $25 Commodity derivatives 36 8 28 36 25 18 7 25 Liabilities: Commodity derivatives 50 50 50 40 40 40 Long-term deb …

FairValueDisclosuresTextBlock · excerpt; the full note is in the filing

INCOME TAXES Income Tax Rates - The overall income tax rates shown in the following table were computed by dividing income tax expense (benefit) by income before income taxes. The effective income tax rates were different than the federal statutory rate primarily due to state income taxes, net of federal benefits (primarily from state income taxes in Iowa and Wisconsin), production tax credits, investment tax credits, amortization of excess deferred taxes and the effect of rate-making on property-related differences. Also impacting Alliant Energys and IPLs effective income tax rates for the three and six months ended June 30, 2026 were additional tax credits during 2026 from renewable generation and energy storage projects previously placed in service, as well as projects currently expected to be placed in service during 2026. Alliant Energys effective income tax rate for the six months ended June 30, 2026 was also impacted by changes in state income tax apportionment. Alliant Energy IPL WPL Three Months Six Months Three Months Six Months Three Months Six Months 2026 2025 2026 2025 2026 2025 2026 2025 2026 2025 2026 2025 Overall income tax rate (44%) (33%) (41%) (31%) (103%) (61%) (71%) (58%) (8%) (6%) (8%) (5%) Deferred Tax Assets and Liabilities - Carryforwards - At June 30, 2026, the carryforwards and expiration dates were estimated as follows (in millions): Range of Expiration Dates Alliant Energy IPL WPL Federal net operating losses Indefinite $47 $14 $ State net operati …

IncomeTaxDisclosureTextBlock · excerpt; the full note is in the filing

Environmental Credits - In May 2026, the Financial Accounting Standards Board issued an accounting standard that establishes recognition, measurement, presentation and disclosure requirements for environmental credits and environmental credit obligations. The standard requires environmental credits to be evaluated based on their intended use in determining whether the costs of such credits are recognized as assets and how those assets are subsequently measured. The standard also establishes a framework for recognizing and measuring environmental credit obligations and requires expanded annual and interim disclosures regarding environmental credits and environmental credit obligations, including information about the nature, intended use, measurement and settlement of environmental credits and related obligations. Alliant Energy, IPL and WPL currently expect to adopt this standard on January 1, 2028. Upon adoption, the standard is required to be applied retrospectively through a cumulative-effect adjustment to the opening retained earnings balance as of January 1, 2028. Alliant Energy, IPL and WPL are currently evaluating the impact of this standard on their financial condition and results of operations and do not currently anticipate a material increase in environmental credit assets or environmental credit obligations upon adoption.

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RELATED PARTIES Service Agreements - Pursuant to service agreements, IPL and WPL receive various administrative and general services from an affiliate, Corporate Services. These services are billed to IPL and WPL at cost based on expenses incurred by Corporate Services for the benefit of IPL and WPL, respectively. These costs consisted primarily of employee compensation and benefits, fees associated with various professional services, depreciation and amortization of property, plant and equipment, and a return on net assets. Corporate Services also acts as agent on behalf of IPL and WPL pursuant to the service agreements. As agent, Corporate Services enters into energy, capacity, ancillary services, and transmission sale and purchase transactions within MISO. Corporate Services assigns such sales and purchases among IPL and WPL based on statements received from MISO. The amounts billed for services provided, sales credited and purchases for the three and six months ended June 30 were as follows (in millions): IPL WPL Three Months Six Months Three Months Six Months 2026 2025 2026 2025 2026 2025 2026 2025 Corporate Services billings $67 $50 $115 $97 $66 $48 $113 $95 Sales credited 4 1 11 2 25 40 65 62 Purchases billed 110 107 206 200 23 16 34 35 Net intercompany payables to Corporate Services were as follows (in millions): IPL WPL June 30, 2026 December 31, 2025 June 30, 2026 December 31, 2025 Net payables to Corporate Services $145 $135 $85 $84 ATC - Pursuant to various agreem …

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REVENUES Disaggregation of revenues from contracts with customers is provided for each reportable segment (IPL and WPL), as well as by customer class within electric and gas sales, as follows (in millions): Alliant Energy IPL WPL Three Months Ended June 30 2026 2025 2026 2025 2026 2025 Electric Utility: Retail - residential $309 $295 $151 $142 $158 $153 Retail - commercial 221 211 143 135 78 76 Retail - industrial 251 240 126 118 125 122 Wholesale 36 49 14 36 35 Bulk power and other 44 56 11 9 33 47 Total Electric Utility 861 851 431 418 430 433 Gas Utility: Retail - residential 44 41 23 21 21 20 Retail - commercial 25 20 13 10 12 10 Retail - industrial 3 3 2 2 1 1 Transportation/other 10 12 5 7 5 5 Total Gas Utility 82 76 43 40 39 36 Other Utility: Steam (a) 9 9 Other utility 2 2 1 2 1 Total Other Utility 2 11 1 11 1 Non-Utility and Other: Travero and other 26 23 Total Non-Utility and Other 26 23 Total revenues $971 $961 $475 $469 $470 $469 Alliant Energy IPL WPL Six Months Ended June 30 2026 2025 2026 2025 2026 2025 Electric Utility: Retail - residential $641 $618 $311 $297 $330 $321 Retail - commercial 442 425 285 271 157 154 Retail - industrial 491 475 249 236 242 239 Wholesale 71 97 28 71 69 Bulk power and other 103 88 22 16 81 72 Total Electric Utility 1,748 1,703 867 848 881 855 Gas Utility: Retail - residential 206 188 99 95 107 93 Retail - commercial 111 94 48 43 63 51 Retail - industrial 9 8 4 4 5 4 Transportation/other 27 26 15 16 12 10 Total Gas Utility 353 316 16 …

RevenueFromContractWithCustomerTextBlock · excerpt; the full note is in the filing

SEGMENTS OF BUSINESS Alliant Energys two reportable segments are IPL and WPL. Certain financial information relating to Alliant Energys, IPLs and WPLs reportable segments and reconciliation to consolidated amounts, was as follows (in millions): Utility Total Alliant Reportable Energy Three Months Ended June 30, 2026 IPL WPL Segments Other Consolidated Electric utility revenues $431 $430 $861 N/A $861 Gas utility revenues 43 39 82 N/A 82 Other revenues 1 1 2 $26 28 Total revenues 475 470 945 26 971 Electric production fuel and purchased power expense 45 87 132 N/A 132 Electric transmission service expense 98 57 155 N/A 155 Cost of gas sold expense 22 15 37 N/A 37 Other operation and maintenance expense 108 87 195 14 209 Other segment items: Depreciation and amortization expense 119 98 217 3 220 Interest expense 57 49 106 37 143 Equity income from unconsolidated investments, net (1) (1) (42) (43) Income tax benefit (33) (6) (39) (13) (52) Other (a) (6) 6 Net income 65 78 143 27 170 Total assets (as of June 30, 2026) 12,872 11,046 23,918 1,400 25,318 Investments in equity method subsidiaries (as of June 30, 2026) 4 20 24 713 737 Construction and acquisition expenditures 293 278 571 37 608 Utility Total Alliant Three Months Ended June 30, 2025 Reportable Energy IPL WPL Segments Other Consolidated Electric utility revenues $418 $433 $851 N/A $851 Gas utility revenues 40 36 76 N/A 76 Other revenues 11 11 $23 34 Total revenues 469 469 938 23 961 Electric production fuel and purchase …

SegmentReportingDisclosureTextBlock · excerpt; the full note is in the filing

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES NOTE 1(a) General - The interim unaudited Financial Statements included herein have been prepared pursuant to the rules and regulations of the SEC. Accordingly, certain information and note disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted, although management believes that the disclosures are adequate to make the information presented not misleading. These Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the 2025 Form 10-K . In the opinion of management, all adjustments, which unless otherwise noted are normal and recurring in nature, necessary for a fair presentation of the results of operations, financial position and cash flows have been made. Results for the three and six months ended June 30, 2026 are not necessarily indicative of results that may be expected for the year ending December 31, 2026. A change in managements estimates or assumptions could have a material impact on financial condition and results of operations during the period in which such change occurred. Certain prior period amounts in the Financial Statements and Notes have been reclassified to conform to the current period presentation for comparative purposes. (b) Leases - Finance Leases - WPL is currently leasing the Sheboygan Falls Energy Facility from AEFs Non-utility Generation business. WPL is responsible for the operation …

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COMMON EQUITY Common Share Activity - A summary of Alliant Energys common stock activity was as follows: Shares outstanding, January 1, 2026 257,137,261 At-the-market offering program 929,759 Shareowner Direct Plan 155,122 Equity-based compensation plans 227,746 Convertible debt settlement (Refer to Note 6 for details) 834,811 Shares outstanding, June 30, 2026 259,284,699 At-the-Market Offering Programs - In March 2026, Alliant Energy fully utilized the remaining capacity under its $1.3 billion 2025 at-the-market offering program and Alliant Energy filed a new prospectus supplement and executed a related distribution agreement, under which it may sell up to $1 billion in aggregate of its common stock through 2029 through an at-the-market offering program that includes an equity forward sales component (the 2026 at-the-market offering program). Alliant Energy expects to use proceeds from the issuance of common stock for general corporate purposes. Alliant Energy entered into forward sale agreements under its 2026 at-the-market offering program with various counterparties who, for the three months ended June 30, 2026, borrowed and sold an aggregate of 6,550,857 shares of Alliant Energy common stock at an aggregate gross sales price of $482 million, including approximately $4 million in commissions, to the counterparties payable by Alliant Energy when the forward sale agreements are settled. Alliant Energy has not yet received any proceeds from this program and no amounts have b …

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