What changed in this filing

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Item 8. Financial Statements and Supplementary Data

2026-02-18 compared with 2025-02-18 · 481 added, 466 removed, 2610 unchanged (27% of the section changed)

359 unchanged sentences

Short-term debt 471 —

Borrowings from money pool — 306

Accounts and wages payable 696 629

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Accounts payable – affiliates 57 74

Interest accrued 69 59

Customer deposits 204 185

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ATXI was incorporated in Illinois in 2006.

ATXI operates, among other assets, the Spoon River, Mark Twain, and Illinois Rivers transmission lines.

Ameren’s and Ameren Missouri’s financial statements are prepared on a consolidated basis and therefore include the accounts of their majority-owned subsidiaries.

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All tabular dollar amounts are in millions, unless otherwise indicated.

Note 1 – Summary of Significant Accounting Policies applies to the Ameren Companies.

The remaining notes to the consolidated financial statements apply to the registrants as indicated in each footnote disclosure.

Registrants are named specifically for their related activities and disclosures.

Our accounting policies conform to GAAP.

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Cash and cash equivalents include short-term, highly liquid investments purchased with an original maturity of three months or less.

Cash and cash equivalents subject to legal or contractual restrictions and not readily available for use for general corporate purposes are classified as restricted cash.

Cash and cash equivalents subject to legal or contractual restrictions and not readily available for use for general corporate purposes are

classified as restricted cash.

See Note 15 – Supplemental Information for a reconciliation of cash, cash equivalents, and restricted cash reported within the balance sheets and the statements of cash flows.

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The allowance is calculated by applying estimated loss factors to various classes of outstanding receivables, including unbilled revenue.

The loss factors used to estimate uncollectible accounts are based upon both historical collections experience and management’s estimate of future collections success given the existing and anticipated future collections environment.

We estimate future collections success using loss factors such as account aging, customer-specific considerations, and forecasted economic conditions.

Accounts receivables are written off when all reasonable collection efforts have been completed.

Ameren Illinois has bad debt riders that adjust rates for net write-offs of customer accounts receivable above or below those being collected in rates.

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We capitalize the cost of additions to, and betterments of, units of property, plant, and equipment.

The cost includes labor, material, applicable taxes, and overhead.

The cost includes labor, material, overheads, and applicable taxes.

An allowance for funds used during construction, as discussed below, is also capitalized as a cost of our rate-regulated assets.

Maintenance expenses related to scheduled Callaway nuclear refueling and maintenance outages are deferred and amortized over the number of expected months until the completion of the next refueling outage, which historically has been approximately 18 months .

Other maintenance expenditures are expensed as incurred.

When units of depreciable property are retired, the original costs, and the associated removal cost, net of salvage, are charged to accumulated depreciation.

Maintenance expenditures are expensed as incurred unless subject to regulatory deferral.

When units of depreciable tangible property are retired, the original costs, and the associated removal cost, net of salvage, are charged to accumulated depreciation.

If environmental expenditures are related to assets currently in use, as in the case of the installation of pollution control equipment, the cost is capitalized and depreciated over the expected life of the asset.

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Ameren Missouri’s cost of nuclear fuel is capitalized as a part of “Property, Plant, and Equipment, Net” on Ameren and Ameren Missouri’s balance sheets and then amortized to “Operating Expenses – Fuel and purchased power” in their respective statements of income on a unit-of-production basis.

Nuclear fuel amortization is reflected as a part of “Amortization of nuclear fuel” on their respective statements of cash flow.

Plant to be Abandoned, Net

Nuclear fuel amortization is reflected as a part of “Amortization of nuclear fuel” on their respective statements of cash flows.

When it becomes probable an asset will be retired significantly in advance of its previously expected useful life and in the near term, the Ameren Companies must assess the probability of recovery of the remaining net book value of the asset to be abandoned.

We recognize a loss on abandonment when it becomes probable that all or part of the cost of an asset, including a return at the applicable WACC, will be disallowed from recovery either through customer rates or through the issuance of securitized utility tariff bonds and such amount is reasonably estimable.

An abandonment loss, if any, would equal the difference between the remaining net book value of the asset and the present value of the expected future cash flows.

If the asset is still in service, the net book value is classified as plant to be abandoned, net, within “Property, Plant, and Equipment, Net” on the balance sheet.

The net book value will be classified as a regulatory asset on the balance sheet when the asset is no longer in service or as required by a rate order.

In relation to the NSR and Clean Air Act litigation discussed in Note 14 – Commitments and Contingencies, Ameren Missouri retired the Rush Island Energy Center on October 15, 2024.

In June 2024, the MoPSC issued a financing order authorizing the issuance of securitized utility tariff bonds by AMF to finance costs related to the accelerated retirement of the Rush Island Energy Center.

In December 2024, AMF issued $ 476 million of securitized utility tariff bonds.

As a result of the financing order and the issuance of the securitized utility tariff bonds, Ameren Missouri concluded no abandonment loss was required for the Rush Island Energy Center and classified the remaining net book value as a regulatory asset as of December 31, 2024.

See Variable Interest Entities below, Note 2 – Rate and Regulatory Matters, and Note 5 – Long-term Debt and Equity Financings for additional information on Ameren Missouri's securitization of the Rush Island Energy Center's costs.

As of December 31, 2023, Ameren and Ameren Missouri determined that the Rush Island Energy Center met the criteria to be considered probable of abandonment and classified its remaining net book value as plant to be abandoned, net, within “Property, Plant, and Equipment, Net” on Ameren’s and Ameren Missouri’s balance sheets.

See Note 3 – Property, Plant, and Equipment, Net for our plant to be abandoned balance as of December 31, 2023.

Depreciation is provided over the estimated lives of the various classes of depreciable tangible property by applying composite rates on a straight-line basis to the cost basis of such property.

In addition, the Ameren Companies must assess the likelihood of a disallowance that part of the cost of a plant under construction or a recently completed plant will be disallowed for ratemaking purposes.

Factors can include our own recent rate orders, as well as recent rate orders of other regulated entities in similar jurisdictions.

If a disallowance becomes probable and reasonably estimable, we record an impairment charge in the period in which we determine the plant has met the criteria.

We also evaluate long-lived assets classified as held and used for impairment when events or changes in circumstances indicate that the carrying value of such assets may not be recoverable.

Whether an impairment has occurred is determined by comparing the estimated undiscounted cash flows attributable to the assets to the carrying value of the assets.

If the carrying value exceeds the undiscounted cash flows, we recognize an impairment charge equal to the amount by which the carrying value exceeds the estimated fair value of the assets.

In the period in which we determine that an asset meets held for sale criteria, we record an impairment charge to the extent the book value exceeds its estimated fair value less cost to sell.

We did not identify any material events or changes in circumstances that indicated that the carrying value of long-lived assets may not be recoverable in 2025, 2024, or 2023.

Depreciation is recognized over the estimated lives of the many classes of depreciable tangible property by applying composite rates on a straight-line basis to the original cost of such property.

The composite rates include a provision for the estimated removal cost of property, plant, and equipment retired from service, net of salvage.

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The results of Ameren’s and Ameren Illinois’ qualitative assessment indicated that it was more likely than not that the fair value of each reporting unit exceeded its carrying value as of October 31, 2025, resulting in no impairment of Ameren’s or Ameren Illinois’ goodwill.

Impairment of Long-lived Assets

We evaluate long-lived assets classified as held and used for impairment when events or changes in circumstances indicate that the carrying value of such assets may not be recoverable.

Whether an impairment has occurred is determined by comparing the estimated undiscounted cash flows attributable to the assets to the carrying value of the assets.

If the carrying value exceeds the undiscounted cash flows, we recognize an impairment charge equal to the amount by which the carrying value exceeds the estimated fair value of the assets.

In the period in which we determine that an asset meets held for sale criteria, we record an impairment charge to the extent the book value exceeds its estimated fair value less cost to sell.

We did not identify any events or changes in circumstances that indicated that the carrying value of material long-lived assets may not be recoverable in 2024, 2023, or 2022.

Variable Interest Entities

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AMF was formed in 2024, for the purpose of issuing and servicing securitized utility tariff bonds related to costs for the accelerated retirement of the Rush Island Energy Center.

Ameren Missouri is the primary beneficiary of this entity because it has the power to direct the activities that most significantly impact the economic performance of the company, as well as the obligation to absorb losses or the right to receive benefits from the company.

Ameren Missouri is the primary beneficiary of this entity because it has the power to direct the activities that most significantly impact the economic performance of the entity, as well as the obligation to absorb losses or the right to receive benefits from the entity.

The entity is considered a variable interest entity primarily because its equity capitalization is insufficient to support its operations.

The entity’s primary assets and liabilities are comprised of regulatory assets related to the unrecovered net plant balance associated with the facility, among other costs, and long-term debt.

The entity’s primary assets and liabilities are comprised of regulatory assets related to the unrecovered net plant balance associated with the retired energy center, among other costs, and long-term debt.

Ameren and Ameren Missouri consolidate AMF, which Ameren Missouri wholly owns, and both manages and controls the entity’s operating activities.

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The following table presents the carrying values of AMF’s assets and liabilities included on Ameren’s and Ameren Missouri’s consolidated balance sheets as of December 31, 2025 :

Other current assets (a)

Unbilled revenue (a)

Other current assets (a)(b)

Noncurrent regulatory assets (a)

Current maturities of long term debt (b)

Interest accrued (b)

Long-term debt, net (b)

Current maturities of long term debt (c)

Interest accrued (c)

Current regulatory liabilities (d)

Long-term debt, net (c)

(a) Assets may be used only to meet AMF’s obligations and commitments.

(b) The securitized tariff bondholders have no recourse to Ameren Missouri.

(b) Included in “Restricted cash” on Ameren Missouri’s balance sheet.

(d) Included in “Other current liabilities” on Ameren Missouri’s balance sheet.

Variable Interest Entities that are not Consolidated

As of December 31, 2024 and 2023, Ameren had unconsolidated variable interests in various equity method investments, primarily to advance clean and resilient energy technologies, totaling $ 74 million and $ 73 million, respectively, included in “Other assets” on Ameren’s consolidated balance sheet.

As of December 31, 2025 and 2024, Ameren had unconsolidated variable interests in various equity method investments, primarily to advance innovative energy technologies, totaling $ 64 million and $ 74 million, respectively, included in “Other assets” on Ameren’s consolidated balance sheet.

Any earnings or losses related to these investments are included in “Other Income, Net” on Ameren’s consolidated statement of income and comprehensive income.

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Liabilities for environmental costs are recorded on an undiscounted basis when it is probable that a liability has been incurred and the amount of the liability can be reasonably estimated.

Costs are expensed or deferred as a regulatory asset when it is expected that the costs will be recovered from customers in future rates.

Costs are expensed or deferred as a regulatory asset when it is probable that the costs will be recovered from customers in future rates.

See Note 14 – Commitments and Contingencies for additional information on liabilities for environmental costs.

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Ameren and Ameren Missouri have recorded AROs for retirement costs associated with decommissioning of Ameren Missouri’s Callaway and wind renewable energy centers, certain Ameren Missouri solar energy centers, CCR facilities, and river structures at certain energy centers used for unloading coal and circulating water systems.

Additionally, Ameren, Ameren

Missouri, and Ameren Illinois have recorded AROs for retirement costs associated with asbestos removal and the disposal of certain transformers.

Additionally, Ameren, Ameren Missouri, and Ameren Illinois have recorded AROs for retirement costs associated with asbestos removal and the disposal of certain transformers.

See Note 15 – Supplemental Information for a reconciliation of the beginning and ending carrying amounts of AROs.

Estimated funds collected from customers to pay for the future removal cost of property, plant, and equipment retired from service, net of salvage, represent a cost of removal regulatory liability.

Estimated funds collected from customers to pay for the future removal cost of property, plant, and equipment retired from service, represent a cost of removal regulatory liability.

See the cost of removal regulatory liability balance in Note 2 – Rate and Regulatory Matters.

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As of December 31, 2025, the cash surrender value of COLI at Ameren and Ameren Illinois was $ 219 million (December 31, 2024 – $ 260 million) and $ 126 million (December 31, 2024 – $ 118 million), respectively, while total borrowings against the policies were $ 117 million (December 31, 2024 – $ 110 million) at both Ameren and Ameren Illinois.

Ameren and Ameren Illinois have the right to offset the borrowings against the cash surrender value of the policies and, consequently, present the net asset in “Other assets” on their respective balance sheets.

Ameren and Ameren Illinois have the right to offset the borrowings against the cash surrender value of the policies and,

consequently, present the net asset in “Other assets” on their respective balance sheets.

The net cash surrender value of Ameren’s COLI is affected by the investment performance of a separate account in which Ameren holds a beneficial interest.

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Ameren recognizes as compensation expense the estimated fair value of stock-based compensation on a straight-line basis over the requisite vesting period.

To the extent that actual forfeitures differ from estimated forfeitures, such differences are accounted for as an

adjustment to compensation expense and recorded in the period that estimates are revised.

To the extent that actual forfeitures differ from estimated forfeitures, such differences are accounted for as an adjustment to compensation expense and recorded in the period that estimates are revised.

Compensation cost is ultimately recognized only for awards for which the requisite service was provided.

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We expect that regulators will reduce future revenues for deferred tax liabilities that were initially recorded at rates in excess of the current statutory rate.

Therefore, reductions in certain excess deferred tax liabilities that were recorded because of decreases in the statutory rate have been credited to a regulatory liability.

Therefore, reductions in certain excess deferred tax liabilities that were recorded because of decreases in the statutory

rate have been credited to a regulatory liability.

A regulatory asset has been established to recognize the probable recovery through future customer rates of tax benefits related to the equity component of allowance for funds used during construction, as well as the effects of tax rate increases.

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For deferred tax balances not included in rate base, the revaluation of deferred taxes caused by a change in the statutory rate is recorded as an adjustment to income tax expense on the income statement.

Tax credits other than investment tax credits are recognized as a reduction to income tax expense when earned.

Tax credits other than investment tax credits are recognized as a reduction to income tax expense when earned and realizable.

The benefits for investment tax credits not transferred under the IRA are amortized over the book depreciable lives of the related property.

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See Note 13 – Related-party Transactions for information regarding capital contributions under the tax allocation agreement.

Accounting and Reporting Developments

Improvements to the Accounting for Internal-Use Software

In September 2025, the FASB issued authoritative guidance that made targeted improvements to the accounting for internal-use software.

The guidance requires an entity to capitalize internal-use software costs when management has authorized and committed to funding the software project, and it is probable that the project will be completed and the software will be used to perform its intended function.

This guidance will be effective for the Ameren Companies in the first quarter of 2028.

We are currently assessing the impacts of this guidance on our results of operations, financial position, and liquidity.

Accounting for Government Grants Received by Business Entities

In December 2025, the FASB issued authoritative guidance that established requirements for the recognition, measurement, presentation, and disclosure of government grants received by business entities.

The guidance applies to transfers of monetary or tangible nonmonetary assets from a government to a business entity, excluding income tax credits, below-market loans, and government guarantees.

Under this guidance, government grants are recognized when it is probable that a business entity will comply with the grant’s conditions and will receive the grant.

This guidance will be effective for the Ameren Companies in the first quarter of 2029.

We are currently assessing the impacts of this guidance on our results of operations, financial position, and liquidity.

NOTE 2 – RATE AND REGULATORY MATTERS

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• Certain excess deferred income taxes

• Renewable energy standard costs

• Property taxes

• Production and investment tax credits or proceeds from the sale of certain tax credits allowed under the IRA

• Electric distribution service and energy-efficiency revenue requirement reconciliation adjustments (a)

• Renewable solutions program revenues and costs (a)

• Electric distribution service and energy-efficiency revenue requirement reconciliation adjustments (b)

• Power procurement

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• Revenue requirement reconciliation adjustment

(a) Reconciliation adjustments under an MYRP are subject to a reconciliation cap which limits annual adjustment to 105 %.

(a) Ameren Missouri’s renewable solutions program allows certain commercial, industrial, and governmental customers who enroll in the program to receive up to 100 % of their energy from renewable resources.

(b) Reconciliation adjustments under an MYRP are subject to a reconciliation cap which limits annual adjustment to 105 %.

See below for additional information regarding the reconciliation cap.

The MoPSC regulates rates and other matters for Ameren Missouri’s electric service and natural gas distribution businesses.

The rates Ameren Missouri charges customers for these services are established in a traditional regulatory rate review, which takes up to 11 months to complete, based on a historical test year and the revenue requirement established in the review.

The rates Ameren Missouri charges customers for these services are established in a traditional regulatory rate review, which takes up to 11 months to complete, based on a historical test year.

Pursuant to the PPRA discussed below, beginning in July 2026, Ameren Missouri will be allowed to file regulatory rate reviews for natural gas delivery service using a future test year, subject to MoPSC approval.

Ameren Missouri has recovery mechanisms, including the RESRAM, FAC, MEEIA, PGA, and WNAR, as well as a rider related to the securitization of the Rush Island Energy Center, that allow customer rates to be adjusted without a traditional regulatory rate review.

These riders, along with the PISA, each described in more detail below, partially mitigate the effects of regulatory lag.

Ameren Missouri also employs other recovery mechanisms, including a renewable energy standard cost tracker, as well as electric and natural gas trackers for certain excess deferred income taxes, property taxes, and pension and postretirement benefit costs.

Ameren Missouri also employs other recovery mechanisms, including a renewable solutions program revenue and cost tracker, as well as electric and natural gas trackers for certain excess deferred income taxes, property taxes, and pension and postretirement benefit costs.

Each of these trackers allows Ameren Missouri to defer the difference between actual costs incurred and costs included in customer rates as a regulatory asset or regulatory liability, with the difference expected to be reflected in base rates in a subsequent MoPSC rate order.

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The PISA permits Ameren Missouri to defer and recover 85 % of the depreciation expense for investments in qualifying property, plant, and equipment placed in service and not included in base rates.

Investments not eligible for recovery under the PISA include amounts related to new nuclear and natural gas generating units and service to new customer premises.

Investments not eligible for recovery under the PISA include amounts related to new nuclear generation facilities and service to new customer premises.

Additionally, the PISA permits Ameren Missouri to earn a return at the applicable WACC on 85 % of rate base that incorporates those qualifying investments, as well as changes in total accumulated depreciation excluding retirements and plant-related deferred income taxes since the previous regulatory rate review.

The regulatory asset for accumulated PISA deferrals also earns a return at the applicable WACC until added to rate base prospectively.

Ameren Missouri recognizes an offset to “Interest Charges” on its consolidated statement of income for its carrying cost of debt relating to each return allowed under the PISA, with the difference between the applicable WACC and its carrying cost of debt recognized in revenues when recovery of PISA deferrals is reflected in customer rates.

Approved PISA deferrals are recovered over a period of 20 years following a

regulatory rate review.

Ameren Missouri recognizes

an offset to “Interest Charges” on its consolidated statement of income for its carrying cost of debt relating to each return allowed under the PISA, with the difference between the applicable WACC and its carrying cost of debt recognized in revenues when recovery of PISA deferrals is reflected in customer rates.

Approved PISA deferrals are recovered over a period of 20 years following a regulatory rate review.

Additionally, under the RESRAM, Ameren Missouri is permitted to recover the 15 % of depreciation expense not recovered under the PISA, and earn a return at the applicable WACC for investments in renewable generation plant placed in service to comply with Missouri’s renewable energy standard.

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Those investments not eligible for recovery under the PISA and the remaining 15 % of certain property, plant, and equipment placed in service, unless eligible for recovery under the RESRAM, remain subject to regulatory lag.

As a result of the PISA election, additional provisions of the law apply to Ameren Missouri, including limitations on electric customer rate increases.

Pursuant to a Missouri law, Ameren Missouri’s PISA election was extended through December 2028 and an additional extension through December 2033 is allowed if requested by Ameren Missouri and approved by the MoPSC, among other things.

This law also established a 2.5 % annual limit on increases to the electric service revenue requirement used to set customer rates, compared to the revenue requirement established in the immediately preceding rate order, due to the inclusion of incremental PISA deferrals in the revenue requirement.

The limitation is effective for revenue requirements approved by the MoPSC after January 1, 2024.

As a result of the PISA election, additional provisions of the law apply to Ameren Missouri, including limitations on electric customer rate increases caused by the inclusion of incremental PISA deferrals in the revenue requirement.

Pursuant to the PPRA discussed below, Ameren Missouri’s PISA election was extended through 2035 and an additional extension through 2040 is allowed if requested by Ameren Missouri and approved by the MoPSC.

This law also reduced the annual limit on increases to the electric service revenue requirement used to set customer rates, compared to the revenue requirement established in the immediately preceding rate order, due to the inclusion of incremental PISA deferrals in the revenue requirement.

The annual limit in effect was 2.5 % and changed to 2.25 %, prorated monthly, for revenue requirements approved by the MoPSC after August 2025.

The RESRAM permits Ameren Missouri to recover or refund, through customer rates, the difference between the cost of compliance, net of production and investment tax credits, with Missouri’s renewable energy standard and the amount set in base rates.

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RESRAM regulatory assets earn carrying costs at short-term interest rates.

The RESRAM permits Ameren Missouri to recover investments in wind generation and other renewables related to compliance with Missouri’s renewable energy standard, and earn a return at the applicable WACC on those investments not already provided for in customer rates or any other recovery mechanism, such as the renewable energy standard cost tracker.

The renewable energy standard cost tracker allows Ameren Missouri to defer differences between actual costs primarily associated with the Maryland Heights Energy Center and renewable energy credits obtained through a 102 -MW power purchase agreement with a wind farm operator, which expired in August 2024, and those costs included in customer rates.

The RESRAM permits Ameren Missouri to recover investments in renewable generation related to compliance with Missouri’s renewable energy standard, and earn a return at the applicable WACC on those investments not already provided for in customer rates or any other recovery mechanism.

The FAC permits Ameren Missouri to recover or refund, through customer rates, 95 % of the variance in net energy costs from the amount set in base rates without a traditional regulatory rate review, subject to MoPSC prudence reviews, with the remaining 5 % of changes retained by Ameren Missouri.

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Ameren Missouri’s base rates for electric service are required to be reset at least every four years to allow for continued use of the FAC.

In June 2024, the MoPSC issued a financing order authorizing the issuance of securitized utility tariff bonds by AMF to finance $ 476 million of costs related to the accelerated retirement of the Rush Island Energy Center, which included the remaining unrecovered net plant balance associated with the facility, among other costs.

Ameren Missouri will collect the amounts necessary to repay the bonds through a rider over approximately 15 years from the date of the December 2024 bond issuance.

In 2024, the MoPSC issued a financing order authorizing the issuance of securitized utility tariff bonds by AMF to finance $ 476 million of costs related to the accelerated retirement of the Rush Island Energy Center, which included the remaining unrecovered net plant balance associated with the facility, among other costs.

Ameren Missouri is collecting the amounts necessary to repay the bonds through a rider over approximately 15 years beginning in December 2024.

The MEEIA permits Ameren Missouri to recover customer energy-efficiency and demand response program costs, the related lost electric revenues, and any performance incentive through the MEEIA without a traditional regulatory rate review, subject to MoPSC prudence reviews.

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The ICC regulates rates and other matters for Ameren Illinois’ electric distribution service and natural gas distribution businesses.

Pursuant to the CEJA, Ameren Illinois may elect to establish electric distribution service rates through either an MYRP or a traditional regulatory rate review.

Pursuant to the CEJA, Ameren Illinois may elect to establish electric distribution service rates through either an MYRP or a traditional regulatory rate review based on a future test year.

See below for additional information regarding the MYRP approved by the ICC, which established rates effective for 2024 through 2027.

The rates Ameren Illinois charges customers for natural gas distribution service are established in a traditional regulatory rate review, which takes up to 11 months to complete, based on a future test year and the revenue requirement established in the review.

Ameren Illinois’ electric distribution service has cost recovery mechanisms in place that allow customer rates to be adjusted without an MYRP or a traditional regulatory rate review.

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The actual revenue requirement for a particular year incorporates Ameren Illinois’ year-end rate base and actual capital structure for such year, provided that the resulting revenue requirement does not exceed the 105 % reconciliation cap and the common equity ratio in such capital structure may not exceed that approved by the ICC in the MYRP.

Ameren Illinois did not exceed the reconciliation cap for the 2024 revenue requirement, which is subject to final reconciliation and ICC review.

Ameren Illinois did not exceed the reconciliation cap for the 2024 and 2025 revenue requirements.

The 2025 revenue requirement is subject to final reconciliation and ICC review.

Ameren Illinois expects to file the 2025 reconciliation with the ICC by May 2026.

Subject to the reconciliation cap, if a given year’s actual revenue requirement collected from customers varies from the approved revenue requirement, an adjustment is made to electric operating revenues with an offset to a regulatory asset or liability to reflect that year’s actual revenue requirement.

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Under the framework, Ameren Illinois was allowed to reconcile its revenue requirement for customer rates established through 2023.

Ameren Illinois’ 2022 and 2023 revenues reflected each year’s actual recoverable costs, year-end rate base, and a return at the applicable WACC, with the ROE component based on the annual average of the monthly yields of the 30-year United States Treasury bonds plus 580 basis points.

The 2022 revenue requirement reconciliation adjustment was collected from customers in 2024, and the 2023 adjustment will be collected in 2025.

Ameren Illinois’ 2023 revenues reflected 2023 actual recoverable costs, 2023 year-end rate base, and a return at the applicable WACC, with the ROE component based on the annual average of the monthly yields of the 30-year United States Treasury bonds plus 580 basis points.

The 2023 revenue requirement reconciliation adjustment was collected from customers in 2025.

Ameren Illinois’ electric customer energy-efficiency rider provides Ameren Illinois’ electric distribution service business with recovery of, and return on, energy-efficiency investments.

Under formula ratemaking for its electric energy-efficiency investments, the revenue requirements are based on recoverable costs, year-end rate base, and a year-end ratemaking capital structure, and earn a return at the applicable WACC.

The ROE component of the applicable WACC is based on the annual average of the monthly yields of the 30-year United States Treasury bonds plus 580 basis points and any performance-related basis-point adjustments, described in more detail below.

Therefore, Ameren Illinois’ annual ROE for its electric energy-efficiency investments is directly correlated to the yields on such bonds.

Through 2026, the ROE component of the applicable WACC will continue to be based on the annual average of the monthly yields of the 30-year United States Treasury bonds plus 580 basis points and any performance-related basis-point adjustments, described in more detail below.

Therefore, Ameren Illinois’ annual ROE for its electric energy-efficiency investments is directly correlated to the yields on such bonds through 2026.

Pursuant to the CRGA discussed below, beginning in 2027, the ROE component of the applicable WACC for a given year will be that year’s ICC approved ROE for Ameren Illinois’ electric distribution service.

Regulatory assets applicable to formula ratemaking for electric energy-efficiency investments earn a return at the applicable WACC.

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In 2022, the ICC issued an order approving total ROE incentives and penalties of 24 basis points under the MYRP, allocated among seven performance metrics.

These performance metrics include improvements in service reliability in both the frequency and duration of outages, a reduction in peak loads, an increased percentage of spend with diverse suppliers, a reduction in disconnections for certain customers, and improved timeliness in response to customer requests for interconnection of distributed energy resources.

These performance metrics apply annually from 2024 through 2027 under the MYRP, and the impact of any incentives and penalties will be excluded from the reconciliation cap described above.

In addition, the allowed ROE on energy-efficiency investments can be increased or decreased up to 200 basis points, depending on the achievement of annual energy savings goals.

In addition, the allowed ROE on energy-efficiency investments can be increased or decreased up to 200 basis points, depending on the achievement of annual energy savings and demand goals.

Any adjustments to the allowed ROE for energy-efficiency investments will depend on annual performance for a historical period relative to energy savings goals.

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Proceedings and Updates

2024 Electric Service Regulatory Rate Review

In June 2024, Ameren Missouri filed a request with the MoPSC seeking approval to increase its annual revenues for electric service.

In February 2025, Ameren Missouri filed an updated electric rate increase request seeking approval to increase its annual revenues for electric service by $ 446 million.

The electric rate increase request is based on a 10.25 % ROE, a capital structure composed of 52 % common equity, a rate base of $ 13.9 billion, and a test year ended March 31, 2024, with certain pro-forma adjustments through the true-up date of December 31, 2024.

Ameren Missouri also requested the continued use of all of its existing riders and trackers.

The electric rate increase request reflects the following:

• increased infrastructure investments made under Ameren Missouri’s Smart Energy Plan, including increased cost of capital and depreciation expense.

Included in these investments are 500 megawatts of solar generation investment for the Boomtown, Cass County and Huck Finn projects along with investments in the Callaway nuclear energy center and other dispatchable generation to support a reliable, low-cost and cleaner mix of energy resources;

• decreased costs resulting from the retirement of the Rush Island Energy Center;

• decreased costs related to the extension of the retirement date of the Sioux Energy Center from 2030 to 2032 to ensure reliability.

In February 2025, the MoPSC staff recommended an increase to Ameren Missouri's annual electric service revenues of $ 384 million based on a 9.74 % ROE, a capital structure composed of 52 % common equity, and a rate base of $ 13.9 billion.

The MoPSC staff’s recommendation includes adjustments for lower off-system sales revenue, production tax credits, and renewable energy credits as a result of the curtailed nighttime operations at the High Prairie Energy Center to limit its impact on protected species.

See Note 14 – Commitments and Contingencies for additional information on the curtailed nighttime operations at the High Prairie Energy Center.

The MoPSC staff supported the continued use of all of Ameren Missouri’s existing riders and trackers.

In December 2024, the MoOPC challenged 25 % to 45 % of the costs and requested return associated with the High Prairie Energy Center investment included in Ameren Missouri’s requested revenue requirement as a result of the curtailed nighttime operations at the energy center discussed above.

The MoPSC proceeding relating to the proposed electric service rate changes will take place over a period of up to 11 months, with a decision by the MoPSC expected by May 2025 and new rates effective by June 2025.

Ameren Missouri cannot predict the level of any electric service rate change the MoPSC may approve, whether the requested regulatory recovery mechanisms will be continued, or whether any rate change that may eventually be approved will be sufficient for Ameren Missouri to recover its costs and earn a reasonable return on its investments when the rate change goes into effect.

2024 Natural Gas Delivery Service Regulatory Rate Review

In September 2024, Ameren Missouri filed a request with the MoPSC seeking approval to increase its annual revenues for natural gas delivery service by $ 40 million.

The natural gas rate increase request is based on a 10.25 % ROE, a capital structure composed of 52 % common equity, a rate base of $ 531 million, and a test year ended March 31, 2024, with certain pro-forma adjustments expected through the true-up date of December 31, 2024.

The request includes the continued use of all of Ameren Missouri’s existing riders and trackers.

The natural gas rate increase request reflects investments in our existing natural gas infrastructure to ensure the safe delivery of natural gas.

The MoPSC proceeding relating to the proposed natural gas delivery service rate changes will take place over a period of up to 11 months, with a decision by the MoPSC expected by August 2025 and new rates effective by September 2025.

Ameren Missouri cannot predict the level of any natural gas delivery service rate change the MoPSC may approve, whether the requested regulatory recovery mechanisms will be continued, or whether any rate change that may eventually be approved will be sufficient for Ameren Missouri to recover its costs and earn a reasonable return on its investments when the rate change goes into effect.

Generation Facilities

Ameren Missouri, and certain subsidiaries of Ameren Missouri, are parties to agreements to acquire and/or construct various generation facilities.

The solar generation facilities are eligible for recovery under the PISA.

The Castle Bluff Natural Gas Project is eligible for recovery under the post-construction cost deferral discussed below.

The following table provides information with respect to each agreement:

Agreement type Facility size Status of MoPSC CCN Status of FERC approval of acquisition In-service date (a)

Huck Finn Solar Project (b)(c)

Build-transfer 200 -MW

Approved February 2023 Received March 2023 December 2024

Boomtown Solar Project (c)(d)

Build-transfer 150 -MW

Approved April 2023 Received October 2023 December 2024

Cass County Solar Project (c)(d)

Development-transfer 150 -MW

Approved June 2024 Not applicable December 2024

Vandalia Solar Project (e)(f)

The PPRA became effective in August 2025.

Pursuant to the law, the PISA has been modified to include new natural gas generating units placed in service after the effective date of the law as qualifying property, plant, and equipment eligible for deferral and recovery of 85 % of the related depreciation expense.

These new natural gas generating units will also be included in the 85 % of rate base allowed to earn a return at the applicable WACC under the PISA.

The law also reduced the annual limit on increases to the electric service revenue requirement used to set customer rates, compared to the revenue requirement established in the immediately preceding rate order, due to the inclusion of incremental PISA deferrals in the revenue requirement.

The annual limit in effect was 2.5 % and changed to 2.25 %, prorated monthly, for revenue requirements approved by the MoPSC after August 2025.

Furthermore, the PISA's expiration date has been extended through 2035, unless Ameren Missouri requests and receives MoPSC approval of an extension through 2040.

The law also requires an electric utility to develop and submit to the MoPSC schedules that include its service tariff applicable to certain large load customers.

These schedules must reasonably ensure that such high-demand customers’ rates reflect a representative share of the costs incurred to serve them and must prevent other lower-demand customer rates from reflecting any unjust or unreasonable costs arising from service provided to these high-demand customers.

In addition, the law made modifications to integrated resource planning, which requires Missouri electric utilities to file plans for meeting their customers' long-term energy needs.

By August 2027, the MoPSC will publish a schedule for Missouri electric utilities to file integrated resource plans every four years .

The MoPSC will be required to issue an order on the plans and shall determine whether the electric utility has submitted sufficient documentation and selected preferred resource plans representing a reasonable and prudent means of serving the utility's load obligations at just and reasonable rates.

In making this determination, the MoPSC shall consider whether the plans appropriately balance specific factors described in the law.

If the MoPSC approves the plans, requests for CCNs for new generation facilities to be constructed or acquired as a part of the approved plans shall be deemed necessary and convenient and the scope of the CCN proceedings to review projects will be limited.

The approved generation facilities will also be eligible to include construction work in progress in rate base, subject to MoPSC approval, which would improve the timeliness of cash recovery.

Utilities are not allowed to capitalize allowance for funds used during construction on amounts included in rate base under this provision.

The amount of construction work in progress to be included in rate base is limited to prudently incurred expenditures made within the construction period for the facility.

Further, outside of the integrated resource planning process discussed above, the law allows a Missouri electric utility to request that the MoPSC authorize the inclusion of construction work in progress for new natural gas-fired generation facilities in rate base.

Under this provision, utilities are not allowed to capitalize allowance for funds used during construction on projects approved to include construction work in progress in rate base.

The amount of construction work in progress to be included in rate base is limited to prudently incurred expenditures made within the construction period for the facility.

The provisions allowing for the inclusion of construction work in progress on natural gas-fired generation in rate base expire in December 2035, unless Ameren Missouri requests and receives MoPSC approval of an extension through 2045.

Also, beginning in July 2026 the law allows natural gas utilities to file regulatory rate reviews using a future test year, subject to MoPSC approval.

If a natural gas utility is allowed to use a future test year, a reconciliation of the actual rate base and certain forecasted costs will be performed 45 days after the end of the test year.

If a given year’s actual revenue requirement is less than the revenue requirement approved by the MoPSC due to changes in rate base or certain other costs, an adjustment is made to reduce natural gas operating revenues with an offset to a regulatory liability to reflect that test year’s amounts.

The regulatory liability will then be refunded to customers in the next regulatory rate review and will accrue carrying costs at the applicable WACC.

April 2025 MoPSC Electric Rate Order

In April 2025, the MoPSC issued an order in Ameren Missouri’s 2024 electric service regulatory rate review, approving nonunanimous stipulations and agreements.

The order authorized an increase of $ 355 million to Ameren Missouri’s annual revenue requirement for electric retail service, effective June 1, 2025.

The approved revenue requirement was based on infrastructure investments as of December 31, 2024.

The order did not explicitly specify an ROE, capital structure, rate base, or any rate base disallowances.

The order provides for the continued use of all existing riders and trackers.

The order also changed annualized depreciation, regulatory asset and liability amortization amounts, and the base level of expenses for trackers.

On an annualized basis, these changes reflect an increase in “Depreciation and amortization” of approximately $ 70 million, among other expense changes, on Ameren’s and Ameren Missouri’s consolidated statements of income.

July 2025 MoPSC Natural Gas Rate Order

In July 2025, the MoPSC issued an order in Ameren Missouri’s 2024 natural gas delivery service regulatory rate review, approving a unanimous stipulation and agreement.

The order authorized an increase of $ 32 million to Ameren Missouri’s annual revenue requirement for natural gas delivery service, effective September 1, 2025.

The order did not explicitly specify an ROE, capital structure, rate base, or any rate base disallowances.

The order provides for the continued use of all of Ameren Missouri’s existing riders and trackers.

Large Load Customer Rate Plan

In November 2025, the MoPSC approved Ameren Missouri’s request to modify its existing large primary service tariff, pursuant to the PPRA, to require customers requesting 75 MWs or more of demand and who are served at transmission level voltage to comply with additional tariff terms.

The additional terms include a service term of 12 years plus a ramp period of up to five years to reach peak demand, minimum demand charges of 80 % of contracted capacity, customer exit terms and fees, and customer credit and collateral requirements, among other terms.

In addition, new customer programs would be available under this tariff, which allow customers to support renewable generation, battery storage, and/or nuclear generation through incremental payments.

The MoPSC order also includes an earnings sharing mechanism that would apply if Ameren Missouri’s earned ROE for a calendar year exceeds 9.74 %, which can be adjusted by the MoPSC in future electric rate orders.

If this were to occur, Ameren Missouri would defer 65 % of the return in excess of the 9.74 % ROE to a regulatory liability, which would be returned to retail electric customers in a future rate review.

In addition, if large load customer revenues were reduced in a calendar year due to certain events, as determined by the MoPSC, Ameren Missouri may defer a portion of the reduced revenues to a regulatory asset to be included in its revenue requirement in the next electric rate review.

In February 2026, Ameren Missouri executed electric service agreements with large load customers consistent with the tariff terms discussed above, representing 2.2 gigawatts of demand.

Ameren and Ameren Missouri do not expect a material impact to their results of operations, financial position, or liquidity in 2026 related to these agreements.

Generation and Storage Facilities

Ameren Missouri is party to agreements to acquire and/or construct various generation and storage facilities that are consistent with the 2025 Change to the 2023 PRP.

The generation and storage facilities are eligible for recovery under the PISA.

The following table provides information with respect to each facility:

Agreement type Facility size Status of MoPSC CCN In-service date (a)

Vandalia Solar Project (b)

Self-build 50 -MW

Approved March 2024 Not applicable Fourth quarter 2025

Bowling Green Solar Project (e)(f)

Approved March 2024 December 2025

Bowling Green Solar Project (b)

Self-build 50 -MW

Approved March 2024 Not applicable First quarter 2026

Split Rail Solar Project (e)(f)

Build-transfer 300 -MW

Approved March 2024 Received November 2024 Mid-2026

Castle Bluff Natural Gas Project (e)

Approved March 2024 First quarter 2026

Split Rail Solar Project Build-transfer (c)

Approved March 2024 Second quarter 2026

Castle Bluff Natural Gas Project (d)

Self-build 800 -MW

Approved October 2024 (g)

Not applicable Fourth quarter 2027

(a) In-service dates are dependent on the timing of construction completion, among other things.

The assets of the Huck Finn, Boomtown, and Cass County solar projects were placed in service in December 2024.

(b) The Huck Finn Solar Project is expected to support Ameren Missouri’s compliance with the state of Missouri’s renewable energy standard.

Investments in the project are eligible for recovery under the RESRAM.

(c) Ameren Missouri acquired the Cass County, Boomtown, and Huck Finn solar projects in June 2024, September 2024, and October 2024, respectively, and placed the assets of the projects, totaling $ 1 billion, in service in December 2024.

(d) The Boomtown and Cass County solar projects are expected to support Ameren Missouri’s transition to renewable energy generation and serve customers under the Renewable Solutions Program, which allows certain commercial, industrial, and governmental customers who enroll in the program to receive up to 100 % of their energy from renewable resources.

(e) These projects collectively represent approximately $ 1.7 billion of expected capital expenditures.

(f) These solar projects are expected to support Ameren Missouri’s transition to renewable energy generation.

(g) For additional information see Castle Bluff Natural Gas Project CCN and Post-Construction Cost Deferral below.

Castle Bluff Natural Gas Project CCN and Post-Construction Cost Deferral

In October 2024, the MoPSC issued an order approving a nonunanimous stipulation and agreement filed by Ameren Missouri, the MoPSC staff, and other intervenors requesting a CCN for the Castle Bluff Natural Gas Project.

The order also includes the use of a post-construction cost deferral related to the Castle Bluff Natural Gas Project, which allows Ameren Missouri to defer and recover depreciation expense, financing costs, and applicable income taxes incurred from the date the project is placed in service to the date when project costs are reflected in updated base rates as a result of a regulatory rate review.

The period of deferral would be limited to the earlier of the time the project costs are reflected in base rates or six months.

Securitization of Rush Island Energy Center Costs

Ameren Missouri will collect the amounts necessary to repay the bonds over approximately 15 years from the date of bond issuance.

The securitized tariff bonds were issued in December 2024.

The financing order also included a determination that the decision to retire the Rush Island Energy Center was reasonable and prudent.

The MoPSC did not make a determination regarding the prudency of Ameren Missouri's prior actions that resulted in the adverse ruling in the NSR and Clean Air Act litigation discussed in Note 14 – Commitments and Contingencies, however, claims regarding such actions could be considered in future regulatory proceedings.

If future regulatory proceedings result in revenue reductions based on Ameren Missouri’s prior actions that resulted in the adverse ruling in the NSR and Clean Air Act litigation, it could have a material adverse effect on the results of operations, financial position, and liquidity of Ameren and Ameren Missouri.

Base rate revenues relating to the recovery of the Rush Island Energy Center are being deferred as a regulatory liability since the October 15, 2024 retirement date of the facility until new rates become effective related to the current electric service regulatory rate review.

The amortization period for the regulatory liability will be determined in a future regulatory rate review.

See Note 5 – Long-term Debt and Equity Financings for additional information on the securitized tariff bonds issuance.

In 2024, 2023, and 2022, Ameren Missouri achieved certain energy-efficiency spending goals for the MEEIA 2019 program.

As a result of achieving these spending goals and MoPSC order issued in August 2022, Ameren Missouri recognized performance incentive revenues of $ 13 million, $ 12 million, and $ 22 million, respectively.

In November 2024, the MoPSC issued an order approving a nonunanimous stipulation and agreement for Ameren Missouri’s MEEIA 2025 plan, which includes a portfolio of customer energy-efficiency and demand response programs, along with the continued use of the MEEIA rider, which allows Ameren Missouri to collect from customers its actual MEEIA program costs, related lost electric revenues, and performance incentives.

Ameren Missouri intends to invest $ 51 million annually in 2025 and 2026 and $ 22 million in 2027 for customer energy-efficiency and demand response programs.

In addition, the order approved performance incentives applicable to each plan year to earn revenues by achieving certain spending and demand response goals.

If 100 % of the goals are achieved in 2025, 2026, and 2027, Ameren Missouri would earn performance incentive revenues of $ 5 million, $ 5 million, and $ 2 million, respectively.

Approved October 2024 Fourth quarter 2027

Big Hollow Battery Energy Storage Project (e)

Self-build 400 -MW

Approved February 2026 Second quarter 2028

Big Hollow Natural Gas Project (e)

Self-build 800 -MW

Approved February 2026 Third quarter 2028

Reform Solar Project Self-build 250 -MW

Filed August 2025 (f)

Fourth quarter 2028

(a) In-service dates are dependent on the timing of regulatory approvals and construction completion, among other things.

(b) These projects collectively represent approximately $ 0.2 billion of capital expenditures.

In February 2026, Ameren Missouri acquired the Split Rail Solar Project, which includes solar panels, project design, land rights, and engineering, procurement, and construction agreements, for approximately $ 0.6 billion, and took over construction management of the project.

(d) This project represents approximately $ 0.9 billion of capital expenditures.

(e) These projects represent approximately $ 2 billion of capital expenditures.

(f) Ameren Missouri expects a decision by the MoPSC in the first half of 2026.

In 2024, the MoPSC issued an order approving a nonunanimous stipulation and agreement for Ameren Missouri’s MEEIA 2025 plan, which includes a portfolio of customer energy-efficiency and demand response programs, along with the continued use of the MEEIA rider, which allows Ameren Missouri to collect from customers its actual MEEIA program costs, related lost electric revenues, and performance incentives.

Ameren Missouri intends to invest $ 51 million in 2026 and $ 22 million in 2027 for customer energy-efficiency and demand response programs.

In addition, the order approved an immaterial amount of performance incentives applicable to each plan year to earn revenues by achieving certain spending and demand response goals.

MISO Long-Range Transmission Projects CCN

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A portion of these projects were assigned or awarded via a competitive bid process to various utilities, including Ameren.

In 2024, ATXI filed requests for CCNs, among other things, with the MoPSC related to the MISO long-range transmission projects that it expects to construct within the MoPSC’s jurisdiction.

Decisions by the MoPSC are expected in 2025.

In December 2023, the ICC issued an order in Ameren Illinois' MYRP proceeding approving base rates for electric distribution services for 2024 through 2027 and rejecting Ameren Illinois' Grid Plan, which was addressed as part of the MYRP proceeding.

Rate changes consistent with the December 2023 order became effective in January 2024 and remained effective through late June 2024, when new rates became effective pursuant to the June 2024 ICC rehearing order discussed below.

The December 2023 order adopted an alternative methodology to establish a rate base and revenue requirements for the years 2024 through 2027 using Ameren Illinois’ previously approved 2022 year-end rate base.

In January 2024, the ICC partially denied a rehearing requested by Ameren Illinois to revise the allowed ROE in the December 2023 order and granted Ameren Illinois’ rehearing request to reconsider the rate base for each year of the MYRP and to include a base level of investments to maintain grid reliability in each year of the MYRP.

In June 2024, the ICC issued an order on Ameren Illinois’ rehearing request, which revised the rate bases for Ameren Illinois’ MYRP test years to include investments for 2023 through 2027, among other things.

New rates became effective in late June 2024 and remained effective through late December 2024, when new rates became effective pursuant to the December 2024 ICC order discussed below.

For additional information on the ICC’s June 2024 rehearing order, see the table below.

In July 2024, Ameren Illinois filed a request for rehearing of the ICC’s June 2024 rehearing order to include an asset associated with other postretirement benefits in the rate base.

Subsequently, in August 2024, the ICC denied the rehearing request.

Also, in January 2024, Ameren Illinois filed an appeal of the December 2023 ICC order, including the 8.72 % ROE, and subsequently updated the appeal filing in September 2024 to include the June 2024 rehearing order regarding the inclusion of an asset associated with other postretirement benefits in the rate base to the Illinois Appellate Court for the Fifth Judicial District.

The court is under no deadline to address the appeal and Ameren Illinois cannot predict the ultimate outcome of the appeal.

In March 2024, pursuant to the December 2023 ICC order discussed above, Ameren Illinois filed a revised Grid Plan and a revised MYRP to update the requested revenue requirements for 2024 through 2027.

In December 2024, the ICC issued an order in connection with Ameren Illinois’ revised Grid Plan and revised MYRP for electric distribution service for 2024 through 2027.

In July and December 2025, the MoPSC issued orders approving requests filed by ATXI for CCNs, among other things, related to the portion of the MISO long-range transmission projects it will construct within the MoPSC’s jurisdiction.

In December 2024, the ICC issued an order in connection with a revised Grid Plan and a revised MYRP filed by Ameren Illinois in March 2024, approving revenue requirements for electric distribution services for 2024 through 2027 of $ 1,206 million, $ 1,287 million, $ 1,367 million, and $ 1,421 million, respectively.

Using the 2023 revenue requirement as a starting point, the approved revenue requirements in the ICC’s December 2024 order represent a cumulative four-year increase of $ 308 million.

Rate changes consistent with the December 2024 order became effective in December 2024.

In January 2025, Ameren Illinois filed a request for rehearing of the ICC’s December 2024 order to revise the allowed ROE and to include an asset associated with other postretirement benefits in the rate base, among other things.

Subsequently, in February 2025, the ICC denied the rehearing request.

Ameren Illinois intends to file an appeal of the ICC’s December 2024 order and update the appeal filed in September 2024 to the Illinois Appellate Court for the Fifth Judicial District as discussed above.

The following table presents the approved revenue requirements and average annual rate base in the ICC’s December 2024 MYRP order and the ICC’s June 2024 rehearing order:

Year Revenue Requirement (in millions) Average Annual Rate Base (in billions)

ICC’s December 2024 MYRP Order (a) :

2024 $ 1,206 $ 4.2

2025 $ 1,287 $ 4.4

2026 $ 1,367 $ 4.6

2027 $ 1,422 $ 4.8

ICC’s June 2024 Rehearing Order (a) :

2024 $ 1,196 $ 4.0

2025 $ 1,282 $ 4.3

2026 $ 1,350 $ 4.5

2027 $ 1,397 $ 4.7

(a) Based on an allowed ROE of 8.72 % and a capital structure composed of 50 % common equity.

The ROE is under appeal, as discussed above.

New rates became effective in December 2024.

2023 Electric Distribution Revenue Requirement Reconciliation Adjustment Order

In March 2025, Ameren Illinois filed an appeal of the ICC’s December 2024 order to the Illinois Appellate Court for the Fifth Judicial District to revise the allowed ROE and to include an asset associated with other postretirement benefits in the rate base, among other things.

In addition, Ameren Illinois filed an appeal related to orders issued by the ICC in December 2023 and June 2024 related to the MYRP proceeding.

The appellate court is under no deadline to address the appeals, and Ameren Illinois cannot predict the ultimate outcome of the appeals.

2024 Electric Distribution Service Revenue Requirement Reconciliation Adjustment Order

In December 2025, the ICC issued an order approving Ameren Illinois’ 2024 electric distribution service revenue requirement reconciliation adjustment filing.

This order approved a reconciliation adjustment of $ 158 million, which reflected Ameren Illinois’ actual 2023 recoverable costs, year-end rate base of $ 4.2 billion, and capital structure composed of 50 % common equity.

This order approved an adjustment increasing the allowed revenue requirement by $ 48 million, which reflected Ameren Illinois’ actual 2024 recoverable costs, year-end rate base of $ 4.2 billion, and capital structure composed of 50 % common equity.

The approved reconciliation adjustment will be collected from customers in 2026.

In February 2026, the ICC denied Ameren Illinois’ rehearing request to include an asset associated with other postretirement benefits in the rate base, among other things.

Ameren Illinois is assessing whether to pursue an appeal with the Illinois Appellate Court for the Fifth Judicial District in the first half of 2026.

Electric Customer Energy-Efficiency Investments

In November 2024, the ICC issued an order in Ameren Illinois’ annual update filing that approved electric customer energy-efficiency rates of $ 126 million beginning in January 2025, which represents an increase of $ 26 million from 2024 rates.

In November 2025, the ICC issued an order in Ameren Illinois’ annual update filing that approved an electric customer energy-efficiency revenue requirement of $ 138 million beginning in January 2026, which represents an increase of $ 12 million from the 2025 revenue requirement.

This order was based on a projected 2026 year-end rate base of $ 474 million.

2025 Natural Gas Delivery Service Rate Review

In January 2025, Ameren Illinois filed a request with the ICC seeking approval to increase its annual revenues for natural gas delivery service by $ 140 million.

The request is based on a 10.7 % ROE, a capital structure composed of 52 % common equity, and a rate base of $ 3.3 billion.

Ameren Illinois used a 2026 future test year in this proceeding.

A decision by the ICC in this proceeding is required by early December 2025, with new rates expected to be effective in December 2025.

Ameren Illinois cannot predict the level of any delivery service rate change the ICC may approve, nor whether any rate change that may eventually be approved will be sufficient to enable Ameren Illinois to recover its costs and to earn a reasonable return on investments when the rate changes go into effect.

In January 2026, Ameren Illinois filed its Grid Plan for the years 2028 through 2031.

The Grid Plan will be used to align capital expenditures to operational needs and will impact rate base for future rate reviews under an MYRP or traditional rate review.

An order from the ICC is expected in December 2026.

Electric Energy Efficiency Plan

In August 2025, the ICC issued an order approving Ameren Illinois’ energy-efficiency plan that includes annual investments in electric energy-efficiency programs of approximately $ 126 million per year from 2026 through 2029.

The ICC has the ability to reduce the amount of electric energy-efficiency savings goals in future program years if there are insufficient cost-effective programs available, which could reduce the investments in electric energy-efficiency programs.

Pursuant to the CRGA, Ameren Illinois is required to file an updated energy-efficiency plan for 2027 through 2029 by June 1, 2026 to reflect the spending cap increases discussed below.

In January 2026, the CRGA was enacted and will become effective in June 2026.

The law includes certain provisions that affect Ameren Illinois’ annual investments in energy-efficiency programs, and the related return on those investments.

Under the law, the annual spending cap for energy-efficiency investments will increase to $ 178 million, $ 222 million, and $ 256 million for 2027, 2028, and 2029, respectively.

In addition, beginning in 2027, the ROE component of the applicable WACC used to calculate Ameren Illinois’ return on energy-efficiency investments for the year will be that year’s ICC-approved ROE for Ameren Illinois’ electric distribution service.

The allowed ROE can be increased or decreased up to 200 basis points, depending on the achievement of annual energy savings and demand goals.

2025 Natural Gas Delivery Service Rate Order

In November 2023, the ICC issued an order in Ameren Illinois’ January 2023 natural gas delivery service regulatory rate review, which resulted in an increase to its annual revenues for natural gas delivery service of $ 112 million based on a 9.44 % allowed ROE, a capital structure composed of 50 % common equity, and a rate base of approximately $ 2.85 billion.

The order reflected a reduction of approximately $ 93 million of planned distribution and transmission capital investments included in Ameren Illinois’ requested revenue increase, which used a 2024 future test year.

The new rates became effective on November 28, 2023.

In December 2023, Ameren Illinois filed a request for rehearing of the ICC's November 2023 order.

The filing requested the ICC revise the order to include an allowed ROE of at least 9.89 %, a capital structure composed of 52 % common equity, and a reversal of the approximately $ 93 million reduction of planned distribution and transmission capital investments included in the order, among other things.

In January 2024, the ICC denied Ameren Illinois’ rehearing request, and Ameren Illinois filed an appeal with the Illinois Appellate Court for the Fifth Judicial District.

In January 2025, the appellate court ruled on the appeal filed by Ameren Illinois.

In that ruling, the court reversed a reduction of planned transmission capital investments of $ 48 million, but affirmed the ICC-approved 9.44 % ROE and the remaining reduction of planned distribution capital investments.

Future of Gas Proceeding

The ICC’s November 2023 natural gas delivery service rate order discussed above directed the ICC staff to develop a plan for a future of gas proceeding.

All of the Illinois natural gas utilities subject to ICC regulation are included in this proceeding, which is exploring issues involving the decarbonization of the natural gas distribution system in light of the state of Illinois’ goal of economy-wide 100 % clean energy by

2050, pursuant to the CEJA.

Some of the issues being addressed include the mitigation of any natural gas distribution stranded assets, the role of energy efficiency in decarbonization, and the associated impacts of natural gas decarbonization to the electric distribution system, among others.

A final ICC staff report is expected in early 2026 and will be used by the ICC to guide further action, if any.

In November 2025, the ICC issued an order in Ameren Illinois’ January 2025 natural gas delivery service regulatory rate review, which resulted in an increase to its annual revenues for natural gas delivery service of $ 79 million based on a 9.60 % ROE, a capital structure composed of 50 % common equity, a 2026 future test year, and a rate base of $ 3.2 billion.

The order reflected a reduction of $ 75 million of

planned distribution and transmission capital investments included in Ameren Illinois’ future test year request.

The new rates became effective December 2025.

In January 2026, Ameren Illinois filed an appeal of the ICC’s November 2025 order and the ICC’s January 2026 order rejecting Ameren Illinois’ rehearing request to the Illinois Appellate Court for the Fifth Judicial District.

The appeal challenged the inclusion of the non-service cost component of the net periodic benefit income related to other postretirement benefits in the annual revenue requirement and the $ 75 million reduction of planned capital investments, among other things.

The court is under no deadline to address the appeal, and Ameren Illinois cannot predict the ultimate outcome of the appeal.

QIP Reconciliation Hearing

Pursuant to Illinois law, 2014 was the first year of the QIP.

In 2021, Ameren Illinois filed a request with the ICC to initiate a reconciliation proceeding of natural gas capital investments recovered under the QIP rider during 2020.

In September 2024, the Illinois Attorney General’s office challenged the recovery of capital investments that were made during 2020, alleging that the ICC should disallow approximately $ 30 million in natural gas capital investments as improper and imprudent, resulting in a potential over-recovery of an immaterial amount by Ameren Illinois in 2020.

In October 2023, and again in September 2024, the ICC staff filed testimony that supports the prudence and reasonableness of the capital investments made during 2020.

Ameren Illinois’ 2020 QIP rate recovery request under review by the ICC was within the rate increase limitations allowed by law.

Ameren Illinois recovered similar investments in each of the 2014 to 2019 annual reconciliations.

In September 2024, the Illinois Attorney General’s office challenged the recovery of capital investments that were made during 2020, alleging that the ICC should disallow $ 30 million in natural gas capital investments as imprudent, unsupported, or ineligible to be recovered through the QIP resulting in a potential over-recovery of an immaterial amount by Ameren Illinois in 2020.

In 2023, and again in 2024, the ICC staff filed testimony that supports the prudence and reasonableness of the capital investments made during 2020.

Ameren Illinois’ 2020 QIP rate recovery request under review by the ICC is within the rate increase limitations allowed by law.

The ICC is under no deadline to issue an order in this proceeding.

Ameren Illinois included $ 529 million of eligible natural gas capital investments in the QIP from 2021 to 2023.

In addition, 2021 through 2023 reconciliation proceedings are still ongoing.

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A portion of these projects were assigned or awarded via a competitive bidding process to various utilities, including Ameren.

In February 2024, Ameren Illinois and ATXI filed a request for a CCN, among other things, with the ICC related to the portion of the MISO long-range transmission projects they will construct within the ICC’s jurisdiction.

A decision by the ICC is expected by mid-2025.

In July 2025, the ICC issued an order approving a request filed by Ameren Illinois and ATXI for a CCN, among other things, related to the portion of the MISO long-range transmission projects they will construct within the ICC’s jurisdiction.

MISO Transmission Rate Incentives

In 2024, the MISO approved a first set of second tranche projects related to its preliminary long-range transmission planning roadmap of projects through 2039.

A portion of these projects were assigned to Ameren and are estimated to cost approximately $ 1.3 billion, based on the MISO’s cost estimate.

In July 2025, the FERC approved transmission rate incentives relating to the second tranche projects assigned to Ameren.

The incentives will allow construction work in progress to be included in rate base for projects constructed by ATXI, thereby improving the timeliness of cash recovery, and would allow recovery of prudently incurred costs, subject to FERC approval, for any portion of the projects if they are abandoned for reasons beyond the control of Ameren.

ATXI will not capitalize allowance for funds used during construction on the related projects.

FERC ROE Complaint Cases

Since November 2013, the allowed base ROE for FERC-regulated transmission rate base under the MISO tariff has been subject to customer complaint cases and has been changed by various FERC orders.

In May 2020, the FERC issued an order, which set the allowed base ROE to 10.02 % and required refunds, with interest, for the periods from November 2013 to February 2015 and from late September 2016 forward.

Ameren and Ameren Illinois paid these refunds, including interest, by March 31, 2022.

In 2020, Ameren Missouri, Ameren Illinois, and ATXI, as well as various customers, petitioned the United States Court of Appeals for the District of Columbia Circuit for review of the May 2020 order, challenging certain aspects of the new ROE methodology established.

The petition filed by Ameren Missouri, Ameren Illinois, and ATXI challenged the refunds required for the period from September 2016 to May 2020.

In August 2022, the court issued a ruling that granted the customers’ petition for review, vacated the FERC’s previous MISO ROE-determining orders, and remanded the proceedings to the FERC.

The court elected not to rule on the issues raised by Ameren Missouri, Ameren Illinois, and ATXI.

In October 2024, the FERC issued an order, which decreased the allowed base ROE from 10.02 % to 9.98 % and required refunds, with interest, for the same periods covered by the May 2020 order.

In November 2024, the MISO transmission owners, including Ameren Missouri, Ameren Illinois, and ATXI, filed a request for rehearing with the FERC, arguing, among other things, the FERC should not have ordered refunds back to September 2016 or imposed interest on those refunds.

Also in November 2024, another intervenor filed a request for rehearing with the FERC, requesting the FERC correct aspects of the ROE methodology used in the October 2024 order and reconsider its decision in a February 2015 complaint case to deny refunds for the period from February 2015 to May 2016.

In December 2024, the FERC issued a notice indicating a future order related to the rehearing requests will be issued but did not specify a timeline.

In January 2025, the MISO transmission owners, including Ameren Missouri, Ameren Illinois, and ATXI, filed an appeal of the October 2024 order to the United States Court of Appeals for the District of Columbia Circuit.

As a result of the October 2024 order, Ameren and Ameren Illinois recognized reductions to "Operating Revenues – Electric" on their statements of income of $ 10 million and $ 7 million, respectively, and recognized expense of $ 2 million and $ 1 million, respectively, in “Interest charges” on their statements of income in 2024.

As of December 31, 2024, Ameren and Ameren Illinois had recorded liabilities in "Current regulatory liabilities" on their balance sheets of $ 12 million and $ 8 million, respectively, to reflect the expected refunds, including interest, associated with the allowed base ROE set by the October 2024 order.

In October 2024, the FERC issued an order, which decreased the allowed base ROE from 10.02 % to 9.98 % and required refunds, with interest, for the periods from November 2013 to February 2015 and from late September 2016 forward.

In January and April 2025, the MISO transmission owners, including Ameren Missouri, Ameren Illinois, and ATXI, filed appeals of the October 2024 order and a March 2025 FERC order that rejected all rehearing requests to the United States Court of Appeals for the District of Columbia Circuit.

The appellate court is under no deadline to address the appeals.

Regulatory Assets and Liabilities

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31 — 31 66 — 66

Rush Island Energy Center base rate revenue deferral (ac)

31 — 31 13 — 13

Other 24 67 94 1 43 50

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(c) The difference between Ameren Illinois’ electric distribution service annual revenue requirement calculated under the IEIMA performance-based formula ratemaking framework and the revenue requirement included in customer rates for that year.

The under-recovery will be recovered from customers with a return at the applicable WACC within two years .

The under-recovery was recovered from customers with a return at the applicable WACC in 2025.

(d) These assets earn a return at the applicable WACC.

(e) The difference between Ameren Illinois' actual electric distribution revenue requirement, as adjusted for certain cost variations, and the ICC-approved revenue requirement, subject to a reconciliation cap.

(e) The difference between Ameren Illinois' actual annual electric distribution revenue requirement, as adjusted for certain cost variations, and the ICC-approved revenue requirement, subject to a reconciliation cap.

The under-recovery will be recovered from customers with a return at the applicable WACC within two years .

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Any under-recovery or over-recovery will be recovered from, or refunded to, customers within two years .

(h) Under-recovered natural gas revenue caused by sales volume deviations from weather normalized sales approved by the ICC in rate regulatory reviews.

(h) Under-recovered natural gas revenue caused by sales volume deviations from weather normalized sales approved by the ICC in regulatory rate reviews.

Each year’s amount will be recovered from customers from April through December of the following year.

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The period of refund varies based on MoPSC approval in a regulatory rate review.

The amortization period will be determined in a future regulatory rate review.

Amounts included in the accumulation period approved in the April 2025 MoPSC electric rate order, discussed above, are being amortized over five years beginning June 2025.

An amortization period for subsequent accumulations will be established in a future rate review.

(j) A rider for the difference between the level of bad debt write-offs, net of any subsequent recoveries, incurred by Ameren Illinois and the level of such costs included in electric distribution and natural gas delivery service rates.

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(q) In June 2024, the MoPSC issued a financing order authorizing the issuance of securitized utility tariff bonds by AMF to finance costs related to the accelerated retirement of the Rush Island Energy Center, which includes the remaining unrecovered net plant balance associated with the facility, among other costs.

Ameren Missouri will collect the amounts necessary to repay the securitized utility tariff bonds over approximately 15 years beginning in December 2024.

Ameren Missouri is collecting the amounts necessary to repay the securitized utility tariff bonds over approximately 15 years beginning in December 2024.

(r) Under-recovered costs associated with Ameren Missouri’s compliance with the state of Missouri’s renewable energy standard.

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These costs are being collected over five years beginning in February 2022.

(t) The electric energy-efficiency investments are being amortized over their weighted-average useful lives beginning in the period in which they were made, with current remaining amortization periods ranging from two to 12 years.

(u) A regulatory recovery mechanism for the difference between actual property taxes incurred by Ameren Missouri and the related taxes included in customer rates.

The period of recovery, or refund, varies based on MoPSC approval in a regulatory rate review.

Amounts accumulated through 2022 are being collected over two years beginning July 2023.

The amortization period for amounts accumulated after 2022 will be determined in a future regulatory rate review.

Electric amounts accumulated through 2024 are being amortized over three years beginning June 2025.

Gas amounts accumulated through 2024 are being amortized over five years beginning September 2025.

For electric and natural gas related costs incurred subsequent to 2024, the amortization period will be determined in a future regulatory rate review.

(v) Over-recovered costs from utility customers.

Amounts will be refunded to customers within one year of the deferral.

(w) Estimated funds collected from customers to pay for the future removal cost of property, plant, and equipment when retired from service, net of salvage.

(w) Estimated funds collected from customers to pay for the future removal cost of property, plant, and equipment when retired from service.

(x) The ARO regulatory liability includes the nuclear decommissioning trust fund balance ($ 1,526 million and $ 1,342 million at December 31, 2025 and 2024, respectively), net of recoverable removal costs for AROs ($ 685 million and $ 651 million at December 31, 2025 and 2024, respectively).

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The period of refund varies based on MoPSC approval in a regulatory rate review.

For electric and natural gas related costs incurred prior to 2023 and 2022, respectively, the weighted-average remaining amortization period is two years .

For electric and natural gas related costs incurred after 2023 and 2022, respectively, the amortization period will be determined in a future regulatory rate review.

For electric and natural gas related costs incurred through 2024, the weighted-average remaining amortization period is four years .

For electric and natural gas related costs incurred subsequent to 2024, the amortization period will be determined in a future regulatory rate review.

(aa) Funds collected for the purchase of renewable energy credits and zero emission credits through IPA procurements.

The balance will be amortized as the credits are purchased.

Pursuant to the CEJA, if funds collected from customers are not used to procure renewable energy credits, they would be refunded to customers pursuant to an annual reconciliation proceeding, the latest of which was approved by the ICC in January 2025 and did not result in refunds to customers.

Pursuant to the CEJA, if funds collected from customers are not used to procure renewable energy credits, they would be refunded to customers pursuant to an annual reconciliation proceeding, the latest of which was approved by the ICC in May 2025 and did not result in refunds to customers.

(ab) Funds collected from the issuance of securitized utility tariff bonds by AMF primarily to pay for the decommissioning of the Rush Island Energy Center.

The amortization period for the difference between the estimated costs and the actual costs incurred will be determined in a future regulatory rate review.

(ac) Base rate revenues related to the Rush Island Energy Center collected after the energy center was retired in October 2024, which is being refunded to customers over three years beginning June 2025.

NOTE 3 – PROPERTY, PLANT, AND EQUIPMENT, NET

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28,404 20,095 2,291 50,790

Accumulated depreciation and amortization (f)

10,243 4,783 400 15,426

Accumulated depreciation and amortization 10,875 5,184 436 16,495

17,529 14,911 1,855 34,295

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Other 991 619 131 1,741

Plant to be abandoned, net (e)

Property, plant, and equipment, net $ 18,788 $ 15,530 $ 1,986 $ 36,304

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and 2 to 55 years for other.

(b) Includes $ 30 million and $ 29 million of oil-fired generation at December 31, 2024 and 2023, respectively.

(b) Includes $ 30 million of oil-fired generation at December 31, 2025 and 2024.

(d) Other property, plant, and equipment includes assets used to support electric and natural gas services.

(e) Represents the net book value of the Rush Island Energy Center as Ameren Missouri retired the energy center in October 2024, significantly in advance of its previously expected useful life.

See Plant to be Abandoned, Net under Note 1 – Summary of Significant Accounting Policies, NSR and Clean Air Act Litigation under Note 14 – Commitments and Contingencies, and Securitization of Rush Island Energy Center Costs under Note 2 – Rate and Regulatory Matters for additional information on the accelerated retirement of the Rush Island Energy Center.

(d) Other property, plant, and equipment includes assets used to support electric distribution, electric transmission, and natural gas services.

Capitalized software costs are classified within “Property, Plant, and Equipment, Net” on the balance sheet and are amortized on a straight-line basis over the expected period of benefit, ranging from 2 to 15 years, with the amortization expense included in “Depreciation and amortization” on the statement of income.

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Ameren Illinois 10 10 9 76 82 ( 29 ) ( 36 )

Annual amortization expense for capitalized software placed in service as of December 31, 2024, is estimated to be as follows:

Annual amortization expense for capitalized software classified as in service as of December 31, 2025, is estimated to be as follows:

2026 2027 2028 2029 2030

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Short-Term Borrowings

In December 2024, the Credit Agreements, which were scheduled to mature in December 2027, were extended and now mature in December 2028.

The Credit Agreements provide $ 2.6 billion of credit cumulatively through maturity in December 2028.

In December 2025, the Credit Agreements, which were scheduled to mature in December 2028, were extended and amended.

The Credit Agreements now mature in December 2030.

The Credit Agreements provide $ 3.2 billion of credit cumulatively through maturity.

The total facility size of the Missouri Credit Agreement and Illinois Credit Agreement is $ 1.9 billion and $ 1.3 billion, respectively.

The maturity date of each Credit Agreement may be extended for an additional one-year period upon the mutual consent of the respective borrowers and the lenders.

Credit available under the agreements is provided by 20 international, national, and regional lenders, with no single lender providing more than $ 156 million of credit in aggregate.

Credit available under the agreements is provided by 20 international, national, and regional lenders, with no single lender providing more than $ 208 million of lending capacity across both agreements in the aggregate.

The obligations of each borrower under the respective Credit Agreements to which it is a party are several and not joint.

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In addition, the issuance of letters of credit is subject to the $ 3.2 billion overall combined facility borrowing limitations of the Credit Agreements.

The borrowers will use the proceeds from any borrowings under the Credit Agreements for general corporate purposes, including working capital, loan funding under the Ameren money pool arrangements, and other short-term affiliate loan arrangements.

The borrowers will use the proceeds from any borrowings under the Credit Agreements for general corporate purposes.

The Missouri Credit Agreement and the Illinois Credit Agreement are available to support issuances under Ameren (parent)’s, Ameren Missouri’s and Ameren Illinois’ commercial paper programs, respectively, subject to borrowing sublimits, as well as to support issuance of letters of credit for the borrowers.

Ameren (parent), Ameren Missouri and Ameren Illinois’ use letters of credit to provide financial guarantees for certain operating obligations.

As of December 31, 2025, there were $ 33 million of letters of credit outstanding under the credit facilities, respectively.

Amounts approximate their fair value.

As of December 31, 2025, based on credit capacity available under the Credit Agreements, along with cash and cash equivalents, the net liquidity available to Ameren (parent), Ameren Missouri, and Ameren Illinois, collectively, was $ 2.5 billion.

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The Credit Agreements also contain nonfinancial covenants, including restrictions on the ability to incur certain liens, to transact with affiliates, to dispose of assets, to make investments in or transfer assets to its affiliates, and to merge with other entities.

The Credit Agreements require each of Ameren, Ameren Missouri, and Ameren Illinois to maintain consolidated indebtedness of not more than 65 % of its consolidated total capitalization pursuant to a defined calculation set forth in the agreements.

The Credit Agreements require each of Ameren, Ameren Missouri, and Ameren Illinois to maintain consolidated indebtedness of not more than 67.5 %, 65 %, and 65 %, respectively, of its consolidated total capitalization pursuant to a defined calculation set forth in the agreements.

As of December 31, 2025, the ratios of consolidated indebtedness to total consolidated capitalization, calculated in accordance with the provisions of the Credit Agreements, were 59 %, 49 %, and 45 %, for Ameren, Ameren Missouri, and Ameren Illinois, respectively.

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3.50 % Senior unsecured notes due 2031

5.375 % Senior unsecured debt due 2035

Total long-term debt, gross 4,150 3,400

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2.95 % Senior secured notes due 2027 (a)

3.50 % First mortgage bonds due 2029 (b)

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5.50 % Senior secured notes due 2034 (a)

5.25 % First mortgage bonds due 2035 (b)

5.30 % Senior secured notes due 2037 (a)

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Long-term debt – related parties, gross

( 88 ) ( 58 )

Unamortized discount and premium ( 15 ) ( 17 )

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5.55 % First mortgage bonds due 2054 (g)

5.625 % First mortgage bonds due 2055 (g)

Total long-term debt, gross 6,313 5,913

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Unamortized debt issuance costs ( 2 ) ( 2 )

Maturities due within one year — ( 49 )

Long-term debt, net $ 659 $ 659

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The surcharges collected by Ameren Missouri on behalf of AMF are remitted to AMF and are not available to creditors of Ameren Missouri.

Principal and interest payments on these bonds are payable semiannually on April 1 and October 1 of each year, beginning October 1, 2025, with final principal and interest payment due October 1, 2039.

Principal and interest payments on these bonds are payable semiannually on April 1 and October 1 of each year, which began on October 1, 2025, with final principal and interest payment due October 1, 2039.

(f) These notes are collaterally secured by first mortgage bonds issued by Ameren Illinois under the Ameren Illinois mortgage indenture.

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In November and December 2024, Ameren (parent) purchased senior secured notes and first mortgage bonds issued by Ameren Missouri and first mortgage bonds issued by Ameren Illinois for $ 44 million in the aggregate.

On a consolidated basis, Ameren (parent)’s repurchase of these senior secured notes and first mortgage bonds were accounted for as a debt extinguishment and resulted in a pre-tax gain of $ 16 million, which is reflected in “Other Income, Net” on Ameren’s consolidated statement of income.

Interest expense related to the repurchased bonds was less than $ 1 million for the year ended December 31, 2024.

In June 2025, Ameren (parent) purchased senior secured notes and first mortgage bonds issued by Ameren Missouri and first mortgage bonds issued by Ameren Illinois for $ 24 million in the aggregate.

On a consolidated basis, Ameren (parent)’s repurchase of these senior secured notes and first mortgage bonds were accounted for as a debt extinguishment and resulted in a pre-tax gain of $ 8 million and $ 16 million for the years ended December 31, 2025 and 2024, respectively, which is reflected in “Other Income, Net” on Ameren’s consolidated statement of income.

Interest expense related to the repurchased bonds was $ 3 million and less than $ 1 million for the years ended December 31, 2025 and 2024, respectively.

The following table presents Ameren Missouri’s and Ameren Illinois’ “Long-term Debt, Net - Related Parties” as of December 31, 2025 and 2024:

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2.625 % First mortgage bonds due 2051

3.90 % First mortgage bonds due 2052

Total long-term debt - related parties, gross 88 58

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3.25 % First mortgage bonds due 2050

2.90 % First mortgage bonds due 2051

Long-term debt - related parties, net $ 5 $ 3

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Shares of common stock issuable under the 401(k) plan are, at Ameren’s option, newly issued shares, treasury shares, or shares purchased in the open market or in privately negotiated contracts.

Ameren has entered into an equity distribution sales agreement pursuant to which Ameren may offer and sell from time to time up to $ 1.75 billion of its common stock through an ATM program, which includes the ability to enter into forward sale agreements.

Ameren has entered into an equity distribution sales agreement pursuant to which Ameren may offer and sell from time to time its common stock through an ATM program, which includes the ability to enter into forward sale agreements.

In August 2025, Ameren increased the amount of common stock available for sale under the ATM program by $ 1.25 billion to a total of $ 3 billion.

Under the ATM, Ameren issued 5.8 million, 2.9 million, and 3.2 million shares of common stock and received proceeds of $ 530 million, $ 233 million, and $ 299 million in 2025, 2024 and 2023, respectively.

These proceeds were net of $ 5 million, $ 2 million and $ 3 million, respectively, in compensation paid to selling agents.

As of December 31, 2024, Ameren had approximately $ 550 million of common stock available for sale under the ATM program, which takes into account the forward sale agreements in effect as of December 31, 2024 discussed below.

The forward sale agreements outstanding as of December 31, 2024, can be settled at Ameren’s discretion on or prior to dates ranging from January 23, 2026 to March 6, 2026.

As of December 31, 2025, Ameren had approximately $ 1.5 billion of common stock remaining available for sale under the ATM program.

In May 2025, Ameren entered into forward sale agreements separate from the ATM program with multiple counterparties relating to 6.4 million shares of common stock, with an initial forward sale price for the agreements of $ 91.89 .

The forward sale agreements can be settled at Ameren’s discretion on or prior to January 15, 2027.

On a settlement date or dates, if Ameren elects to physically settle a forward sale agreement, Ameren will issue shares of common stock to the counterparties at the then-applicable forward sale price.

The initial forward sale price for the agreements ranged from $ 81.00 to $ 93.06 , with an average initial forward sale price of $ 84.14 .

Each forward sale price is subject to adjustment based on a floating interest rate factor equal to the overnight bank funding rate less a spread of 75 basis points, and will be subject to decrease on certain dates specified in the forward sale agreements by specified amounts related to expected dividends on shares of the common stock during the term of the forward sale agreements.

Each initial forward sale price is subject to adjustment based on a floating interest rate factor equal to the overnight bank funding rate less a spread of 75 basis points, and will be subject to decrease on certain dates specified in the forward sale agreements by specified amounts related to expected dividends on shares of the common stock during the term of the forward sale agreements.

If the overnight bank funding rate is less than or more than the spread on any day, the interest rate factor will result in a reduction or an increase, respectively, of the forward sale price.

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The forward sale agreements have been classified as equity transactions.

In January 2025, Ameren entered into a forward sale agreement under the ATM program related to 0.6 million shares of common stock.

The January 2025 forward sale agreement can be settled at Ameren’s discretion on or prior to February 9, 2026.

The forward sale price was initially $ 87.43 for the January 2025 forward sale agreement.

In September 2024, $ 450 million principal amount of Ameren (parent)’s 2.50 % senior unsecured notes matured and was repaid with commercial paper borrowings.

In November 2023, Ameren (parent) issued $ 600 million of 5.70 % senior unsecured notes due December 2026, with interest payable semiannually on June 1 and December 1 of each year, beginning June 1, 2024.

Net proceeds from this issuance were used to repay short-term debt.

In December 2023, Ameren (parent) issued $ 700 million of 5.00 % senior unsecured notes due January 2029, with interest payable semiannually on January 15 and July 15 of each year, beginning July 15, 2024.

In February 2026, $ 350 million principal amount of Ameren (parent)’s 3.65 % senior unsecured notes matured and was repaid with commercial paper borrowings.

In March 2025, Ameren (parent) issued $ 750 million of 5.375 % senior unsecured notes due March 2035, with interest payable semiannually on March 15 and September 15 of each year, beginning September 15, 2025.

Net proceeds from this issuance were used for general corporate purposes, including the repayment of short-term debt.

In September 2024, $ 450 million principal amount of Ameren (parent)’s 2.50 % senior unsecured notes matured and was repaid with commercial paper borrowings.

Ameren Missouri

In April 2025, Ameren Missouri issued $ 500 million of 5.25 % first mortgage bonds due April 2035, with interest payable semiannually on April 15 and October 15 of each year, beginning October 15, 2025.

Net proceeds from this issuance were used to repay short-term debt.

In January 2024, Ameren Missouri issued $ 350 million of 5.25 % first mortgage bonds due January 2054, with interest payable semiannually on January 15 and July 15 of each year, beginning July 15, 2024.

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See Note 2 – Rate and Regulatory Matters for additional information on the securitization of Rush Island Energy Center costs.

In January 2023, Ameren Missouri and Audrain County mutually agreed to terminate a financing obligation agreement related to the CT energy center in Audrain County, which was scheduled to expire in December 2023.

No cash was exchanged in connection with the termination of the agreement as the $ 240 million principal amount of the financing obligation due from Ameren Missouri was equal to the amount of bond service payments due to Ameren Missouri.

Ownership of the energy center was transferred to Ameren Missouri in January 2023, at which time the property, plant, and equipment became subject to the lien of the Ameren Missouri mortgage bond indenture.

In March 2023, Ameren Missouri issued $ 500 million of 5.45 % first mortgage bonds due March 2053, with interest payable semiannually on March 15 and September 15 of each year, beginning September 15, 2023.

Net proceeds from this issuance were used for capital expenditures and to repay short-term debt.

For information on Ameren Missouri’s capital contributions, refer to Capital Contributions in Note 13 – Related-party Transactions.

Ameren Illinois

In March and September 2025, Ameren Illinois issued $ 350 million and $ 350 million, respectively, of 5.625 % first mortgage bonds due March 2055, with interest payable semiannually on March 1 and September 1 of each year, beginning September 1, 2025 and March 1, 2026, respectively.

Net proceeds from the March 2025 issuance were used to repay $ 300 million principal amount of its 3.25 % senior secured notes that matured in March 2025, and net proceeds of both issuances were used to repay a portion of its short-term debt.

In June 2024, Ameren Illinois issued $ 625 million of 5.55 % first mortgage bonds due July 2054, with interest payable semiannually on January 1 and July 1 of each year, beginning January 1, 2025.

Net proceeds from this issuance were used to repay short-term debt.

In May 2023, Ameren Illinois issued $ 500 million of 4.95 % first mortgage bonds due June 2033, with interest payable semiannually on June 1 and December 1 of each year, beginning December 1, 2023.

Net proceeds from this issuance were used to repay $ 100 million principal amount of its 0.375 % first mortgage bonds that matured in June 2023 and short-term debt.

For information on Ameren Illinois’ capital contributions, refer to Capital Contributions in Note 13 – Related-party Transactions.

In August 2024, ATXI issued $ 70 million of 5.17 % senior unsecured notes due September 2039 and $ 70 million of 5.42 % senior unsecured notes due September 2053, pursuant to an August 2024 note purchase agreement.

Both series of senior unsecured notes have interest payable semiannually on March 1 and September 1 of each year, beginning March 1, 2025, and were issued through a private placement offering exempt from registration under the Securities Act of 1933, as amended.

Both series of senior unsecured notes have interest payable semiannually on March 1 and September 1 of each year, which began on March 1, 2025, and were issued through a private placement offering exempt from registration under the Securities Act of 1933, as amended.

Net proceeds from these issuances were used to repay a $ 49 million principal payment of ATXI’s 3.43 % senior unsecured notes at maturity and to repay short-term debt.

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Off-Balance-Sheet Arrangements

At December 31, 2024, none of the Ameren Companies had any material off-balance-sheet financing arrangements, other than their investments in variable interest entities, letters of credit, and the multiple forward sale agreements under the ATM program relating to common stock.

At December 31, 2025, none of the Ameren Companies had any material off-balance-sheet financing arrangements, other than their investments in variable interest entities, letters of credit, and the forward sale agreements relating to common stock.

See Note 1 – Summary of Significant Accounting Policies for further detail concerning variable interest entities.

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Allowance for equity funds used during construction $ 88 $ 76 $ 54

Interest income on industrial development revenue bonds — 1 24

Other interest income 41 41 33

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Allowance for equity funds used during construction $ 56 $ 58 $ 30

Interest income on industrial development revenue bonds — 1 24

Other interest income 9 8 11

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NOTE 7 – DERIVATIVE FINANCIAL INSTRUMENTS

We use derivatives to manage the risk of changes in market prices for natural gas, power, uranium, and interest rates, as well as the risk of changes in rail transportation surcharges through fuel oil hedges.

We use derivatives to manage the risk of changes in market prices for natural gas, power, and interest rates, as well as the risk of changes in rail transportation surcharges through fuel oil hedges.

Such price fluctuations may cause the following:

• an unrealized appreciation or depreciation of our contracted commitments to purchase or sell when purchase or sale prices under the commitments are compared with current commodity prices;

• market values of natural gas and uranium inventories that differ from the cost of those commodities in inventory;

• market values of natural gas that differ from the cost of this commodity in inventory;

• actual cash outlays for interest expense and the purchase of commodities that differ from anticipated cash outlays;

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As of December 31, 2025 and 2024, all commodity contracts that met the definition of a derivative and were not eligible for the NPNS exception received regulatory deferral.

Interest rate hedges discussed below do not receive regulatory deferral and were included in accumulated OCI.

Interest rate hedges entered into by Ameren (parent) and discussed below do not receive regulatory deferral and were included in accumulated OCI as Ameren (parent) is not a rate-regulated entity.

The cash flows from our derivative financial instruments follow the cash flow classification of the hedged item.

In 2024, Ameren (parent) entered into interest rate swaps to hedge a portion of our interest rate risk on cash flows related to forecasted debt issuances through 2026.

The interest rate swaps are designated as cash flow hedges and the corresponding changes in fair value each period are initially recorded on the balance sheet in “Accumulated other comprehensive loss” and reclassified into earnings when the debt is issued and the corresponding interest payments affect earnings during the debt term.

At December 31, 2024, Ameren had interest rate swaps with notional amounts of $ 140 million.

The changes in fair value of the interest rate swaps were immaterial at December 31, 2024 .

Ameren (parent) entered into interest rate swaps to hedge a portion of its interest rate risk on cash flows related to certain forecasted debt issuances to occur in 2026 and 2027.

The interest rate swaps are designated as cash flow hedges and the corresponding changes in fair value each period are initially recorded on the balance sheet in “Accumulated other comprehensive income” and reclassified into earnings when the debt is issued and the corresponding interest payments affect earnings during the debt term.

As of December 31, 2025, and 2024, Ameren had interest rate swaps with notional amounts of $ 820 million and $ 140 million, respectively.

Ameren recorded an unrealized gain, net of income taxes, on the change in fair value of interest rate swaps of $ 3 million and $ 3 million to "Accumulated other comprehensive income" for the years ended December 31, 2025 and 2024.

The following table presents open gross commodity contract volumes by commodity type for derivative assets and liabilities as of December 31, 2025 and 2024.

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Power (in MWhs) — 7 7 — 4 4

Uranium (pounds in thousands) — — — 186 — 186

The following table presents the carrying value and balance sheet location of all derivative commodity contracts, none of which were designated as hedging instruments, as of December 31, 2024 and 2023:

The following table presents the carrying value and balance sheet location of all derivative commodity contracts, none of which were designated as hedging instruments because all qualify for regulatory deferral, as of December 31, 2025 and 2024:

Commodity Balance Sheet Location Ameren

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Illinois Ameren

Fuel oils Other current assets $ — $ — $ — $ 2 $ — $ 2

Other assets — — — — — —

Natural gas Other current assets $ 1 $ 1 $ 2 $ 2 $ 2 $ 4

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Power Other current assets 11 — 11 6 — 6

Other assets — — — — — —

Uranium Other current assets — — — 9 — 9

Other assets — — — — — —

Total assets $ 12 $ 4 $ 16 $ 10 $ 6 $ 16

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In determining our concentrations of credit risk related to derivative instruments, we review our individual counterparties and categorize each counterparty into groupings according to the primary business in which each engages.

As of December 31, 2024, if counterparty groups were to fail completely to perform on contracts, the Ameren Companies’ maximum exposure related to derivative assets, predominantly from financial institutions, would have been immaterial with or without consideration of the application of master netting arrangements or similar agreements and collateral held.

As of December 31, 2025, if counterparty groups were to fail completely to perform on contracts, the Ameren Companies’ maximum exposure related to derivative assets would have been immaterial with or without consideration of the application of master netting arrangements or similar agreements and collateral held.

Certain of our derivative instruments contain collateral provisions tied to the Ameren Companies’ credit ratings.

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Derivative assets – commodity contracts:

Fuel oils $ — $ — $ — $ — $ 2 $ — $ — $ 2

Natural gas — 1 — 1 — 4 — 4

Power — — 11 11 — — 6 6

Uranium — — — — — — 9 9

Total derivative assets – commodity contracts $ — $ 1 $ 11 $ 12 $ — $ 4 $ 6 $ 10

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Natural gas — 10 — 10 — 11 — 11

Power — — — — — — 1 1

Total Ameren Missouri $ 5 $ 10 $ — $ 15 $ 4 $ 11 $ — $ 15

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See Note 10 – Retirement Benefits for tables that set forth, by level within the fair value hierarchy, Ameren’s pension and postretirement plan assets as of December 31, 2025 and 2024.

Level 3 fuel oils, natural gas and uranium derivative contract assets and liabilities measured at fair value on a recurring basis were immaterial for all periods presented.

Level 3 natural gas derivative contract assets and liabilities measured at fair value on a recurring basis were immaterial for all periods presented.

The following table presents the fair value reconciliation of Level 3 power derivative contract assets and liabilities measured at fair value on a recurring basis for the years ended December 31, 2025 and 2024:

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The following table sets forth the carrying amount and, by level within the fair value hierarchy, the fair value of long-term debt (including current portion), disclosed, but not recorded, at at fair value as of December 31, 2024 and 2023:

Long-Term Debt (Including Current Portion):

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December 31, 2024

Ameren 15,970 14,366 467 (c)

Ameren Missouri 6,341 5,800 — 5,800

Ameren Illinois 5,232 4,867 — 4,867

$ 17,579 $ 15,395 $ 538 (c)

Ameren Missouri (d)

7,745 6,926 — 6,926

Ameren Illinois (d)

5,852 5,243 — 5,243

(a) Included unamortized debt issuance costs, which were excluded from the fair value measurement, of $ 136 million, $ 62 million, and $ 56 million for Ameren, Ameren Missouri, and Ameren Illinois, respectively, as of December 31, 2025.

Included unamortized debt issuance costs, which were excluded from the fair value measurement, of $ 129 million, $ 62 million, and $ 51 million for Ameren, Ameren Missouri, and Ameren Illinois, respectively, as of December 31, 2024.

(b) Amount excludes Ameren (parent)’s repurchase of Ameren Missouri’s senior secured notes and first mortgage bonds and Ameren Illinois’ first mortgage bonds in 2024 that were accounted for as a debt extinguishment.

(b) Amount excludes Ameren (parent)’s repurchase of Ameren Missouri’s senior secured notes and first mortgage bonds and Ameren Illinois’ first mortgage bonds that were accounted for as a debt extinguishment.

See Note 5 – Long-term Debt and Equity Financings for additional information.

(d) Amount includes Ameren Missouri’s senior secured notes and first mortgage bonds and Ameren Illinois’ first mortgage bonds that were repurchased by Ameren (parent) in 2024.

(d) Amount includes Ameren Missouri’s senior secured notes and first mortgage bonds and Ameren Illinois’ first mortgage bonds that were repurchased by Ameren (parent) in 2025 and 2024.

The Ameren Companies’ carrying amounts of cash, cash equivalents, and restricted cash approximate fair value and are considered Level 1 in the fair value hierarchy.

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It is assumed that the Callaway Energy Center site will be decommissioned after its retirement through the immediate dismantlement method and removed from service.

The Callaway Energy Center’s operating license expires in 2044.

The Callaway Energy Center’s operating license currently expires in 2044.

Ameren and Ameren Missouri have recorded an ARO for the Callaway Energy Center decommissioning costs at fair value.

Annual decommissioning costs of $ 7 million are included in the costs used to establish electric rates for Ameren Missouri’s customers.

Annual decommissioning costs of $ 7 million have historically been included in the costs used to establish electric rates for Ameren Missouri’s customers.

Every three years , the MoPSC requires Ameren Missouri to file an updated cost study and funding analysis for decommissioning its Callaway Energy Center.

An updated cost study and funding analysis was filed with the MoPSC in December 2023 and reflected within the ARO.

Ameren Missouri’s filing supported no change in electric service rates for decommissioning costs.

There is no deadline by which the MoPSC must issue an order regarding the filing.

In May 2025, the MoPSC issued an order that approved a non-unanimous stipulation and agreement between Ameren Missouri and the MoPSC staff that reduced annual customer contributions for funding the Callaway Energy Center decommissioning costs from $ 7 million to zero , as the trust fund level exceeded the estimated present value of future decommissioning costs at the time of the agreement.

This MoPSC order removed Ameren Missouri’s funding obligation effective in June 2025.

Ameren and Ameren Missouri have classified the investments in debt and equity securities that are held in the nuclear decommissioning trust fund as available for sale, and have recorded all such investments at their fair market value at December 31, 2025 and 2024.

16 unchanged sentences

Cash and cash equivalents 8 — — 8

( 1 ) — — ( 1 )

Total $ 679 $ 865 $ 18 $ 1,526

2 unchanged sentences

Cash and cash equivalents 10 — — 10

( 1 ) — — ( 1 )

Total $ 625 $ 742 $ 25 $ 1,342

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These net assets are recorded in “Pension and other postretirement benefits,” “Other current liabilities,” and “Other deferred credits and liabilities” on Ameren’s consolidated balance sheet.

The increase in the overfunded pension and postretirement benefit plans during 2024 was primarily the result of a 45 -basis-point increase in the pension and other postretirement benefit plan discount rates used to determine the present value of the obligation and an increase in the actual return on plan assets of the pension and postretirement trusts.

The increase in the overfunded pension and postretirement benefit plans during 2025 was primarily the result of an increase in the actual return on plan assets of the pension and postretirement trusts and a 5 -basis-point increase in the pension discount rate used to determine the present value of the obligation.

The overfunded pension and other postretirement benefit plans also resulted in regulatory liabilities on Ameren’s, Ameren Missouri’s, and Ameren Illinois’ balance sheets.

The following table presents the net benefit liability/(asset) recorded on the balance sheets as of December 31, 2024 and 2023:

The following table p resents the net benefit liability/(asset) recorded on the balance sheets as of December 31, 2025 and 2024:

$ ( 954 ) $ ( 734 )

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(a) Liabilities associated with pension and other postretirement benefits are recorded in “Other current liabilities” and “Other deferred credits and liabilities” on Ameren’s, Ameren Missouri’s, and Ameren Illinois’ balance sheets.

In December 2025, Ameren, completed a contract transfer transaction with a third-party insurance company that transferred approximately $ 240 million of plan assets and plan obligations of the Ameren Retirement Plan, associated with approximately 4,200 former Ameren Missouri, Ameren Illinois, and Ameren Services employees, that will assume future and full responsibility to fund and administer their benefit payments.

The transaction is designed to reduce potential volatility with the pension plan assets and liabilities and administrative costs.

There was no change to the pension benefits for any participants because of the transfer.

The transaction was funded by pension plan assets and resulted in an actuarial gain of $ 15 million, which will be amortized in net periodic benefit cost (income) over 10 years through the actuarial (gain) loss component beginning in 2026.

Ameren recognizes the overfunded and underfunded status of its pension and postretirement plans as an asset or a liability on its consolidated balance sheet, with offsetting entries to accumulated OCI and regulatory assets or liabilities.

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Participant contributions — 7 — 7

Actuarial (gain) loss ( 143 ) ( 51 ) 170 17

Actuarial (gain) loss 28 (b)

5 ( 143 ) ( 51 )

Contract transfer (c)

( 240 ) — — —

Benefits paid ( 299 ) ( 68 ) ( 291 ) ( 61 )

5 unchanged sentences

Participant contributions — 7 — 7

Contract transfer (c)

( 240 ) — — —

Benefits paid ( 299 ) ( 68 ) ( 291 ) ( 61 )

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Noncurrent asset $ ( 186 ) $ ( 791 ) $ ( 71 ) $ ( 686 )

Current liability (b)

Noncurrent liability (c)

Current liability (d)

Noncurrent liability (e)

Net asset recognized $ ( 163 ) $ ( 791 ) $ ( 48 ) $ ( 686 )

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(a) Not applicable.

(b) Included in “Other current liabilities” on Ameren’s consolidated balance sheet.

(b) Includes a $ 15 million gain from the contract transfer of defined benefit pension obligations and related plan assets to a third-party insurance company in December 2025 as described above.

(c) Represents the contract transfer of defined benefit pension obligations and related plan assets to a third-party insurance company in December 2025 as described above.

(d) Included in “Other current liabilities” on Ameren’s consolidated balance sheet.

(e) Included in “Other deferred credits and liabilities” on Ameren’s consolidated balance sheet.

The following table presents the assumptions used to determine our benefit obligations at December 31, 2025 and 2024:

2 unchanged sentences

Discount rate at measurement date 5.75 % 5.70 % 5.70 % 5.70 %

Increase in future compensation 4.00 3.50 (a)

4.00 3.50 (a)

Cash balance pension plan interest crediting rate 5.50 5.50 (b) (b)

Medical cost trend rate (initial) (c)

(b) (b) (d) (d)

Medical cost trend rate (ultimate) (c)

(b) (b) 5.00 5.00

(a) As of December 31, 2023, increase in future compensation was 4.00 % in 2024, and 3.50 % thereafter.

(b) Not applicable.

(c) Initial and ultimate medical cost trend rate for certain Medicare-eligible participants was 2.50 % at December 31, 2024 and 2023.

(d) Initial medical cost trend rates of 7.00 % and 6.93 % for pre-Medicare plan participants and 7.00 % and 6.50 % for post-Medicare plan participants at December 31, 2024 and 2023, respectively, trend down to the ultimate rate by 2033 and 2030 , respectively, with a 3.00 % upward adjustment to the post-Medicare trend rate in 2025.

Increase in future compensation 4.00 4.00 4.00 4.00

Cash balance pension plan interest crediting rate 5.50 5.50 (a) (a)

Medical cost trend rate (initial) (b)

(a) (a) (c) (c)

Medical cost trend rate (ultimate) (b)

(a) (a) 5.00 5.00

(a) Not applicable.

(b) Initial and ultimate medical cost trend rate for certain Medicare-eligible participants was 2.50 % at December 31, 2025 and 2024.

(c) Initial medical cost trend rates of 7.50 % and 7.00 % for both pre-Medicare plan participants and post-Medicare plan participants at December 31, 2025 and 2024, respectively, trend down to the ultimate rate by 2036 and 2033 , respectively, with a 3.00 % upward adjustment to the post-Medicare trend rate in 2024.

Ameren determines discount rate assumptions by identifying a theoretical settlement portfolio of high-quality corporate bonds sufficient to provide for a plan’s projected benefit payments.

The settlement portfolio of bonds is selected from a pool of approximately 860 high-quality corporate bonds.

The settlement portfolio of bonds is selected from a pool of high-quality corporate bonds.

A single discount rate is then determined;

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As a result, Ameren expects to fund its pension plans at a level equal to the greater of the pension cost or the legally required minimum contribution.

Based on its assumptions at December 31, 2024, its investment performance in 2024, and its pension funding policy, Ameren does not expect to make material contributions in 2025 and expects to make aggregate contributions of $ 170 million in 2026 through 2029.

Based on its assumptions at December 31, 2025, its investment performance in 2025, and its pension funding policy, Ameren expects to make annual contributions of approximately $ 45 million to $ 50 million in each of the next five years, with aggregate estimated contributions of $ 240 million.

Ameren Missouri and Ameren Illinois estimate that their portion of the future funding requirements will be 35 % and 45 %, respectively.

136 unchanged sentences

Prior service cost (credit) — — — ( 4 ) ( 4 ) ( 4 )

Actuarial (gain) loss ( 67 ) ( 115 ) 25 ( 38 ) ( 45 ) ( 19 )

Actuarial (gain) ( 34 ) ( 67 ) ( 115 ) ( 38 ) ( 38 ) ( 45 )

Total non-service cost components (c)

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(b) Prior service cost (credit) is amortized on a straight-line basis over the average future service of active participants benefiting under the plan amendment.

Net actuarial gains or losses related to the net benefit obligation subject to amortization are amortized on a straight-line basis over 10 years.

The difference between the actual and expected return on plan assets is amortized over 4 years.

Net actuarial gains or losses subject to amortization are amortized on a straight-line basis over 10 years.

Expected return on plan assets is based on a market-related value of assets that recognizes asset (gains) losses over 4 years.

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Medical cost trend rate (initial) (d)

Medical cost trend rate (ultimate) (d)

(a) Increase in future compensation is 4.00 % for 2024 and 3.50 % thereafter for the year ended December 31, 2024, and was 4.50 % for 2023, 4.00 % for 2024, and 3.50 % thereafter for the year ended December 31, 2023.

(b) Cash balance pension plan interest crediting rate is 6.42 % for 2024 and 5.50 % thereafter for the year ended December 31, 2024, and was 5.50 % for 2023 and 2024, and 5.00 % thereafter for the year ended December 31, 2023.

(a) Increase in future compensation is 4.00 % for the year ended December 31, 2025 , 4.00 % for 2024 and 3.50 % thereafter for the year ended December 31, 2024, and 4.50 % for 2023, 4.00 % for 2024, and 3.50 % thereafter for the year ended December 31, 2023.

(b) Cash balance pension plan interest crediting rate is 5.20 % for 2025 and 5.50 % thereafter for the year ended December 31, 2025, was 6.42 % for 2024, and 5.50 % thereafter for the year ended December 31, 2024, and 5.50 % for 2023 and 2024, and 5.00 % thereafter for the year ended December 31, 2023.

(d) Initial and ultimate medical cost trend rate for certain Medicare-eligible participants is 2.50 % for the years ended December 31, 2024 and 2023, and 3.00 % for the year ended December 31, 2022.

(d) Initial and ultimate medical cost trend rate for certain Medicare-eligible participants is 2.50 % for the years ended December 31, 2025, 2024, and 2023.

(e) Initial medical cost trend rates of 7.00 % for pre-Medicare plan participants and 7.00 % for post-Medicare plan participants trend down to the ultimate rate by 2033 with a 3.00 % upward adjustment to the post-Medicare trend rate in 2025.

(f) Initial medical cost trend rates of 6.93 % for pre-Medicare plan participants and 6.50 % for post-Medicare plan participants trend down to the ultimate rate by 2030, with a 3.00 % upward adjustment to the post-Medicare trend rate in 2025.

(g) Initial medical cost trend rates of 7.25 % for pre-Medicare plan participants and 6.75 % for post-Medicare plan participants trend down to the ultimate rate by 2030, with a 3.00 % upward adjustment to the post-Medicare trend rate in 2025.

Ameren sponsors a 401(k) plan for eligible employees.

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Restricted stock units vest and entitle an employee to receive shares of Ameren common stock (plus accumulated dividends) if the individual remains employed with Ameren through the payment date of the awards.

Generally, in the event of a participant’s death or retirement at age 55 or older with five years or more of service, awards vest on a pro-rata basis.

In the event of a participant’s death or retirement at age 55 or older with five years or more of service, awards vest on a pro-rata basis.

The payout date of the awards is approximately 38 months after the grant date.

17 unchanged sentences

The law extends federal production and investment tax credits for projects beginning construction through 2024 and allows for a 10 % adder to the production and investment tax credits for siting projects at existing energy communities as defined in the law, which includes sites previously used for coal-fired generation.

The law also creates clean energy tax credits for projects beginning construction after 2024.

The clean energy tax credits will apply to renewable energy production and investments, along with certain nuclear energy production, and will be phased out beginning in 2033, at the earliest.

The phase-out is triggered when greenhouse gas emissions from the electric generation industry are reduced by at least 75 % from the annual 2022 emission rate or at the beginning of 2033, whichever is later.

The law allows for transferability to an unrelated party for cash of up to 100 % of certain tax credits generated after 2022.

In addition, the law imposes a 15 % minimum tax on adjusted financial statement income, as defined in the law, for corporations whose average annual adjusted financial statement income exceeds $ 1 billion for three consecutive preceding tax years effective for tax years beginning after December 31, 2022.

The law also creates production and investment tax credits for projects beginning construction after 2024.

The production and investment tax credits will apply to renewable energy production and investments, along with certain nuclear energy production.

See the OBBBA below for additional information on revisions to the production and investment tax credits.

The law allows for transferability, subject to revisions made by the OBBBA discussed below, to an unrelated party for cash of up to 100 % of certain tax credits generated after 2022.

Once a corporation exceeds this three-year average annual adjusted financial statement income threshold, it will be subject to the minimum tax for all future tax years.

Additional regulations, interpretations, amendments, or technical corrections to or in connection with the IRA have been and are expected to be issued by the IRS or United States Department of Treasury, which may impact the timing of when the 15 % minimum tax becomes applicable for Ameren.

IRS Natural Gas Repairs and Maintenance Guidance

In April 2023, the IRS issued guidance providing a safe harbor method of accounting for the capitalization or deduction of certain expenditures to maintain, repair, replace, or improve natural gas distribution and transmission property.

Ameren adopted this guidance for the 2024 tax year and, as a result, during December 2024, Ameren, Ameren Missouri, and Ameren Illinois recorded increases to their “plant-related” deferred tax liabilities of $ 123 million, $ 12 million, and $ 111 million, respectively.

The following table presents the principal reasons for the difference between the effective income tax rate and the federal statutory corporate income tax rate for the years ended December 31, 2024, 2023, and 2022:

Ameren Missouri Ameren Illinois Ameren

Federal statutory corporate income tax rate 21 % 21 % 21 %

Increases (decreases) from:

Amortization of excess deferred income taxes (a)

The OBBBA was enacted in July 2025 and includes various income tax provisions, among other things.

The OBBBA modified provisions of the IRA related to production and investment tax credits.

The new law maintains production and investment tax credits for solar and wind projects that begin construction within one year of the OBBBA’s enactment and are placed in-service by the end of 2030.

Projects that begin construction after one year from enactment of the OBBBA but are placed in service by the end of 2027 also remain eligible.

The law provides investment tax credits for battery storage projects that begin construction by the end of 2033, which phase out by the end of 2035.

Renewable energy projects that begin construction in 2026 and beyond that use a certain threshold percentage of materials from prohibited foreign entities, as defined in the OBBBA, are not eligible for the tax credits.

Production tax credits associated with nuclear generation remain unchanged from the IRA and phase out by the end of 2032.

Furthermore, the new law continues to allow for transferability of the production and investment tax credits to an unrelated party for cash but such credits are restricted from being transferred to specified foreign entities, as defined in the OBBBA.

Ameren did not have any material impacts on its results of operations, financial position, and liquidity in 2025 related to the OBBBA.

Implementation of the OBBBA provisions is subject to additional guidance, regulations, interpretations, amendments, or technical corrections that may be issued by the IRS or United States Department of Treasury.

Ameren will continue to monitor and assess any impacts related to the OBBBA.

The following table presents the principal reasons for the difference between the effective income tax expense and rate and the federal statutory corporate income tax expense and rate for the years ended December 31, 2025, 2024, and 2023:

2025 2024 2023

Amortization of deferred investment tax credit ( 1 ) — —

Renewable and other tax credits (b)

Amount Effective Tax Rate Amount Effective Tax Rate Amount Effective Tax Rate

Federal statutory corporate income tax expense and rate $ 335 21 % $ 267 21 % $ 282 21 %

State and local taxes, net of federal income tax (a)

74 5 61 5 64 5

State tax 3 7 5

Renewable energy tax credits (b)

( 61 ) ( 4 ) ( 117 ) ( 9 ) ( 52 ) ( 4 )

Other ( 3 ) — ( 7 ) — ( 6 ) —

Changes in valuation allowances — — ( 4 ) — 5 —

Nontaxable or nondeductible items ( 2 ) — 1 — ( 5 ) —

Other adjustments

Amortization of excess deferred income taxes (c)

( 107 ) ( 7 ) ( 112 ) ( 9 ) ( 98 ) ( 8 )

Revaluation of excess deferred income taxes (d)

( 86 ) ( 5 ) — — — —

Depreciation differences ( 14 ) ( 1 ) ( 8 ) ( 1 ) ( 7 ) —

Effective income tax rate ( 18 ) % 24 % 7 %

Federal statutory corporate income tax rate 21 % 21 % 21 %

Increases (decreases) from:

Amortization of excess deferred income taxes (a)

Other — — 2 — — —

Effective income tax expense and rate $ 136 9 % $ 83 7 % $ 183 14 %

Ameren Missouri

Federal statutory corporate income tax expense and rate $ 166 21 % $ 100 21 % $ 113 21 %

State and local taxes, net of federal income tax (a)

21 3 13 3 14 3

Amortization of deferred investment tax credit ( 1 ) — —

Renewable and other tax credits (b)

Renewable energy tax credits (b)

( 61 ) ( 8 ) ( 113 ) ( 24 ) ( 49 ) ( 10 )

State tax 3 7 5

Effective income tax rate ( 2 ) % 26 % 14 %

Federal statutory corporate income tax rate 21 % 21 % 21 %

Increases (decreases) from:

Amortization of excess deferred income taxes (a)

Other ( 3 ) — ( 4 ) ( 1 ) ( 5 ) ( 1 )

Nontaxable or nondeductible items 1 — 1 — ( 1 ) —

Other adjustments

Amortization of excess deferred income taxes (c)

( 75 ) ( 10 ) ( 79 ) ( 17 ) ( 80 ) ( 15 )

Amortization of deferred investment tax credit ( 1 ) — —

Renewable and other tax credits (b)

Depreciation differences ( 6 ) ( 1 ) ( 5 ) — — —

Effective income tax expense (benefit) and rate $ 43 5 % ( 87 ) ( 18 ) % $ ( 8 ) ( 2 ) %

Ameren Illinois

Federal statutory corporate income tax expense and rate $ 187 21 % $ 171 21 % $ 172 21 %

State and local taxes, net of federal income tax (a)

66 7 62 7 61 7

State tax 3 7 5

Effective income tax rate ( 2 ) % 26 % 14 %

(a) Reflects the amortization of a regulatory liability resulting from the revaluation of accumulated deferred income taxes subject to regulatory ratemaking, which are being refunded to customers.

Renewable energy tax credits — — ( 3 ) — — —

Other ( 1 ) — ( 2 ) — ( 1 ) —

Nontaxable or nondeductible items ( 1 ) — — — ( 1 ) —

Other adjustments

Amortization of excess deferred income taxes (c)

( 31 ) ( 3 ) ( 32 ) ( 4 ) ( 17 ) ( 2 )

Revaluation of excess deferred income taxes (d)

( 61 ) ( 7 ) — — — —

Depreciation differences ( 9 ) ( 1 ) ( 3 ) — ( 5 ) —

Other 3 — — — — —

Effective income tax expense and rate $ 153 17 % $ 193 24 % $ 209 26 %

(a) State taxes in Missouri and Illinois made up the majority of the tax effect in this category for Ameren, Ameren Missouri, and Ameren Illinois.

(b) The benefit of the credits associated with Missouri renewable energy standard compliance is refunded to customers through the RESRAM.

The benefit of the credits associated with the production and investment tax credit tracker will be refunded to customers based on MoPSC approval in a regulatory rate review.

(c) Reflects the amortization of a regulatory liability resulting from the revaluation of accumulated deferred income taxes subject to regulatory ratemaking, which are being refunded to customers.

(d) In 2024, the IRS issued a series of private letter rulings to another taxpayer, which provided guidance on applying IRS normalization rules to the calculation of tax benefits applicable to the ratemaking treatment related to net operating loss carryforwards.

The rulings concluded that, for ratemaking purposes, net operating loss carryforwards should be reflected on a separate company basis and should not be reduced by payments received for the utilization of losses by other affiliates under a tax allocation agreement.

In 2025, the FERC issued an order reflecting implementation of the rules for the other taxpayer who had a similar fact pattern as Ameren Illinois and ATXI.

In addition, in 2025, the ICC issued orders in Ameren Illinois’ 2024 electric distribution service revenue requirement reconciliation adjustment proceeding and in its January 2025 natural gas rate review addressing the impacts of the private letter rulings.

Accordingly, in 2025, Ameren and Ameren Illinois decreased income tax expense by $ 86 million and $ 61 million, respectively, to reflect the revaluation of excess deferred income tax regulatory liabilities resulting from TCJA for FERC-regulated and ICC-regulated jurisdictions pursuant to IRS guidance and recent FERC and ICC orders.

The following table presents the components of income tax expense (benefit) for the years ended December 31, 2025, 2024, and 2023:

66 unchanged sentences

(d) Will expire between 2026 and 2030.

The following table presents the total income taxes paid, net of refunds, including production and investment tax credit sale proceeds, for the years ended December 31, 2025, 2024, and 2023:

Ameren Missouri (a)

Ameren Illinois (a)

2025 2024 2023 2025 2024 2023 2025 2024 2023

$ ( 350 ) $ ( 131 ) $ ( 24 ) $ 79 $ ( 25 ) $ 76 $ ( 309 ) $ ( 92 ) $ ( 37 )

Illinois — — — 39 ( 21 ) 26 34 ( 12 ) 28

Missouri ( 9 ) ( 5 ) 5 — — — ( 37 ) 12 ( 15 )

Total taxes paid $ ( 359 ) $ ( 136 ) $ ( 19 ) $ 118 $ ( 46 ) $ 102 $ ( 312 ) $ ( 92 ) $ ( 24 )

(a) Amounts represent income tax paid, net of refunds, to Ameren (parent), pursuant to the tax allocation agreement.

See Note 1 – Summary of Significant Accounting Policies – Income Taxes for additional information.

(b) Includes production and investment tax credit sale proceeds for Ameren and Ameren Missouri of $ 314 million, $ 95 million, and $ 49 million for the years ended December 31, 2025, 2024, and 2023, respectively.

Uncertain Tax Positions

16 unchanged sentences

Energy Product Agreements

Based on the outcome of IPA-administered procurement events, Ameren Missouri and Ameren Illinois have entered into energy product agreements by which Ameren Missouri agreed to sell, and Ameren Illinois agreed to purchase, a set amount of MWhs at a predetermined price over a specified period of time.

The following table presents the specified performance period, amount of MWhs, and average price per MWh included in the agreements:

IPA Procurement Event Performance Period MWhs Average Price per MWh

September 2020 September 2021 – November 2022 204,800 31

April 2021 July 2022 – November 2022 33,600 34

September 2021 January 2022 – September 2023 136,000 37

Based on the outcome of an IPA-administered procurement event in 2021, Ameren Missouri and Ameren Illinois have entered into an energy product agreement by which Ameren Missouri agreed to sell, and Ameren Illinois agreed to purchase, 136,000 MWhs at an average price of $ 37 per MWh from January 2022 through September 2023.

Interconnection Agreements

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Long-Term Debt, Net - Related Parties

In November and December 2024, Ameren (parent) purchased senior secured notes and first mortgage bonds issued by Ameren Missouri, and first mortgage bonds issued by Ameren Illinois.

In November 2024, December 2024, and June 2025, Ameren (parent) purchased senior secured notes and first mortgage bonds issued by Ameren Missouri, and first mortgage bonds issued by Ameren Illinois.

See Note 5 – Long-term Debt and Equity Financings for additional information.

23 unchanged sentences

Ameren Missouri and Ameren Illinois Operating Revenues 2025 31 1

rent and facility services 2023 32 (b)

rent and facility services 2024 31 1

Ameren Illinois interconnection agreement Operating Revenues 2025 (a) 1

with Ameren Missouri 2024 (a) (b)

Ameren Missouri and Ameren Illinois Operating Revenues 2025 1 5

miscellaneous support services 2023 (b) 2

miscellaneous support services 2024 2 2

Total Operating Revenues 2025 $ 32 $ 7

1 unchanged sentence

agreements with Ameren Missouri 2024 (a) —

Ameren Missouri interconnection agreement Purchased Power 2025 1 (a)

with Ameren Illinois 2024 (b) (a)

Ameren Missouri and Ameren Illinois Purchased Power 2025 10 2

1 unchanged sentence

Total Purchased Power 2025 $ 11 $ 2

Ameren Missouri and Ameren Illinois Other Operations and 2024 $ 1 $ 1

rent and facility services Maintenance 2023 (b) 3

Ameren Missouri and Ameren Illinois Other Operations and 2025 $ (b) $ 3

rent and facility services Maintenance 2024 1 1

Ameren Services support services Other Operations and 2025 177 164

2 unchanged sentences

Maintenance Expenses 2024 170 159

Money pool borrowings (advances) (Interest Charges) 2024 $ ( 4 ) $ (b)

Other Income, Net 2023 (b) (b)

Long-term debt, net - related parties (Interest Charges) 2024 (b) (b)

Money pool borrowings (advances) (Interest Charges) 2025 $ ( 1 ) $ 1

Other Income, Net 2024 ( 4 ) (b)

Long-term debt, net - related parties (Interest Charges) 2025 $ ( 3 ) $ (b)

(a) Not applicable.

8 unchanged sentences

protect water bodies;

manage the handling and disposal of hazardous substances and waste materials;

siting and land use requirements;

and potential ecological impacts.

regulate the handling and disposal of hazardous substances and waste materials;

establish siting and land use requirements;

and protect against ecological impacts.

Complex and lengthy processes are required to obtain and renew approvals, permits, and licenses for new, existing, or modified energy-related facilities.

Additionally, the use and handling of various chemicals or hazardous materials require release prevention plans and emergency response procedures.

Environmental regulations have a significant impact on the electric utility industry and compliance with these regulations could be costly for Ameren Missouri, which operates coal-fired and natural gas-fired energy centers.

Compliance obligations under the Clean Air Act include the NSPS, the MATS, emission allowance programs and the CSAPR, and the National Ambient Air Quality Standards, which are subject to periodic review for certain pollutants.

Collectively, these regulations cover a variety of pollutants, such as SO 2 , particulate matter, NO x , mercury, toxic metals and acid gases, and CO 2 emissions.

Regulations implementing the Clean Water Act govern potential impacts from our operations on water bodies including wetlands subject to the Act, as well as evaluation of the ecological and biological impact of those operations.

Implementation of the Clean Air Act and the Clean Water Act requirements typically occurs through the issuance of permits by state regulators or resource agencies, and capital expenditures associated with compliance could be significant.

Coal-fired energy centers must comply with management and disposal requirements for coal ash under the Resource Conservation and Recovery Act and federal regulations known as the CCR Rule.

Surface impoundments at Ameren Missouri’s coal-fired energy centers are subject to closure and groundwater monitoring requirements and the implementations of corrective measures if necessary.

The individual or combined effects of compliance with existing and new environmental regulations could result in significant capital expenditures, increased operating costs, or the closure or alteration of operations at some of Ameren Missouri’s energy centers.

Additionally, the use and handling of various chemicals and hazardous materials require release prevention plans and emergency response procedures.

Environmental regulations impact the electric utility industry, and compliance obligations could be costly for Ameren Missouri, which operates coal-fired and natural gas-fired energy centers.

Compliance obligations under the Clean Air Act stem from a variety of programs including the NSPS, the MATS, emission allowance programs, the CSAPR, and the National Ambient Air Quality Standards, which are subject to periodic review for certain pollutants.

Collectively, these regulations cover a variety of pollutants, such as SO 2 , particulate matter, NO x , mercury, toxic metals and acid gases, and CO 2 emissions, although the scope of covered pollutants can change.

To the extent our operations impact surface water bodies, including wetlands, the Clean Water Act requires permitting as well as evaluation of the ecological and biological impact of those operations.

Implementation of requirements under the Clean Air Act and the Clean Water Act typically occurs through the issuance of permits by state regulators or resource agencies, and capital expenditures associated with compliance could be significant.

The management and disposal of coal ash from our coal-fired energy centers must comply with federal regulations known as the CCR Rule issued under the Resource Conservation and Recovery Act and require the closure of surface impoundments at our coal-fired energy centers along with groundwater monitoring requirements and the implementations of corrective measures if necessary.

The combined effects of compliance with existing and future environmental regulations could result in significant capital expenditures, increased operating costs, and the potential for closure or alteration of operations at some of Ameren Missouri’s energy centers.

Ameren and Ameren Missouri expect that such compliance costs would be recoverable through rates, subject to MoPSC prudence review, but the timing of costs and their recovery could be subject to regulatory lag.

Additionally, Ameren Missouri’s wind generation facilities may be subject to operating restrictions to limit the impact on protected species.

Since 2021, Ameren Missouri’s High Prairie Energy Center curtailed nighttime operations from April through October to limit impacts on protected species during the critical biological season.

The extent and duration of future curtailments are currently unknown as assessment of mitigation technologies is ongoing.

In Ameren Missouri’s 2024 electric service regulatory rate review, the MoPSC staff and the MoOPC have recommended reductions to the revenue requirement associated with the nighttime curtailment of the High Prairie Energy Center.

See Note 2 – Rate and Regulatory Matters for additional information.

Ameren and Ameren Missouri estimate that they may need to make capital expenditures of $ 900 million to $ 1 billion from 2025 through 2029 to comply with environmental regulations.

Additional capital expenditures for environmental controls beyond 2029 could be required.

These estimates include capital expenditures that may be necessary to comply with regulations issued by the EPA in 2024 relating to CO 2 emissions and MATS discussed below, assuming these regulations are not revised or overturned.

This estimate of capital expenditures also includes surface impoundment closure and corrective action measures required by the 2015 CCR Rule and modifications to cooling water intake structures at existing power plants under Clean Water Act rules in place prior to 2024, all of which are discussed below.

Congress and the EPA could review and revise compliance requirements.

In addition to planned retirements of coal-fired energy centers that will be included in Ameren Missouri’s 2025 Change to the 2023 PRP and as noted below with respect to the NSR and Clean Air Act litigation and Illinois emissions standards, Ameren Missouri’s current plan for compliance with existing air emission regulations includes burning low-sulfur coal and installing new or optimizing existing air pollution control equipment.

Accordingly, the actual amount of capital expenditures required to comply with existing environmental regulations may vary substantially from the above estimates because of uncertainty as to future permitting requirements by state regulators and the EPA, revisions to regulatory obligations, and varying cost of potential compliance strategies, among other things.

Since 2021, Ameren Missouri’s High Prairie Energy Center has curtailed nighttime operations from April through October to limit impacts on protected species during the critical biological season.

Ameren Missouri does not anticipate these operating curtailments will have a material impact on its results of operations, financial position, or liquidity.

In 2026, Ameren Missouri plans to apply for a new federal permit to operate the High Prairie Energy Center which, if approved, would reduce restrictions limiting the energy center’s impact on protected species for 30 years.

The application will also propose various mitigation measures and operating curtailments based on Ameren Missouri’s assessment of mitigation technologies.

Ameren Missouri’s current permit expires in May 2027.

Due to various actions taken by the EPA, which are discussed below, Ameren and Ameren Missouri have revised capital expenditure estimates necessary to comply with environmental regulations to a range of $ 70 million to $ 100 million from 2026 through 2030.

Additional capital expenditures beyond 2030 could be required.

This estimate includes surface impoundment closure and corrective action measures required by the 2015 CCR Rule and modifications to cooling water intake structures at existing power plants under Clean Water Act rules in place prior to 2024, all of which are discussed below.

The EPA could review and revise compliance requirements.

In addition to planned retirements of coal-fired energy centers that were included in Ameren Missouri’s 2025 Change to the 2023 PRP and with respect to the Illinois emissions standards discussed below, Ameren Missouri’s current plan for compliance with existing air emission regulations includes burning low-sulfur coal and optimizing existing air pollution control equipment.

Accordingly, the actual amount of capital expenditures required to comply with existing environmental regulations could vary from the above estimates because of uncertainty as to revisions to regulatory requirements by the EPA and/or state regulators and their timing and varying cost of potential compliance strategies, among other things.

The following sections describe the significant environmental statutes and regulations and environmental enforcement and remediation matters that affect or could affect our operations.

The EPA periodically amends and revises its regulations and proposes amendments to regulations and guidelines, which could ultimately result in the revision of all or part of such regulations.

The EPA could ultimately revise all or part of such federal regulations.

Clean Air Act

Federal and state laws, including the CSAPR, regulate emissions of SO 2 and NO x through the reduction of emissions at their source and the use and retirement of emission allowances.

In April 2022, the EPA proposed the Good Neighbor Rule of the Clean Air Act, which includes additional NO x emission reductions from power plants in Missouri, Illinois, and other states through revisions to the CSAPR.

In January 2023, the EPA issued its final disapproval of Missouri’s proposed state implementation plan for addressing the transport of ozone under the Good Neighbor Rule of the Clean Air Act.

The disapproval of the state plan allowed the EPA to implement revisions to the CSAPR through a federal implementation plan that reduced the amount of NO x allowances available for state budgets and imposed NO x emission limits on electric generating units for Missouri, Illinois, and other states under the Good Neighbor Rule of the Clean Air Act.

In April 2023, the Missouri Attorney General and Ameren Missouri separately filed lawsuits in the United States Court of Appeals for the Eighth Circuit challenging the EPA’s disapproval of the Missouri state plan.

Ameren expected a decision on Missouri’s proposed state implementation plan under the Good Neighbor Rule by the United States Court of Appeals for the Eighth Circuit in 2025, but, in February 2025, the EPA requested that the appellate court suspend the case indefinitely and indicated it was reviewing the basis for the disapproval of the state implementation plans, including Missouri’s.

Ameren Missouri complies with the current CSAPR requirements by minimizing emissions through the use of low-sulfur coal, operation of two scrubbers at its Sioux Energy Center, and optimization of existing NO x air pollution control equipment.

Reducing the amount of state budget NO x allowances for compliance with NO x emission limits under the Good Neighbor Rule could result in additional controls being required on Ameren Missouri’s generating units and/or the reduction of operations.

Any costs for compliance are expected to be recovered from customers, subject to MoPSC prudence review, through the FAC or higher base rates.

Federal and state laws, including the CSAPR, regulate emissions of SO 2 and NO x through the reduction of emissions at their source and the use and retirement of emission allowances available for state budgets.

In 2022, the EPA proposed the Good Neighbor Rule to reduce the transport of ozone from power plants by reducing the amount of CSAPR NO x allowances available for compliance.

The EPA subsequently rejected state implementation plans proposed by Missouri and other states to comply with the Good Neighbor Rule and issued a federal implementation plan.

The disapprovals for some state implementation plans, including Missouri’s, were stayed by multiple appellate courts, and in 2024, the United States Supreme Court issued a stay of the federal implementation plan.

In January 2026, the EPA issued a proposed rule to reconsider the Good Neighbor Rule.

Ameren Missouri complies with the current CSAPR requirements by minimizing emissions with low-sulfur coal, operation of two scrubbers at its Sioux Energy Center, and optimization of existing NO x air pollution control equipment.

If a final rule is issued similar to the proposed rule, Ameren Missouri would not expect additional NO x controls at its coal-fired energy centers to be necessary.

CO 2 Emissions Standards

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Affected power plants are required to comply with the rule through a phased-in approach or retire.

Compliance with the new rule could be required as early as 2030 for certain existing coal-fired power plants and 2032 for certain new natural gas-fired power plants.

In December 2024, the United States Court of Appeals for the District of Columbia Circuit heard arguments from various stakeholders including the EPA, environmental organizations, state attorney generals, and industry groups regarding the legal merits of the final rule.

In February 2025, the EPA requested that the appellate court suspend the case for 60 days and not issue an opinion so the EPA can decide how to proceed.

Ameren and Ameren Missouri estimate capital expenditures of approximately $ 580 million may be necessary to comply with the final rule assuming it is not revised or overturned.

Ameren and Ameren Missouri are monitoring the legal challenges and assessing the impacts of the final rule and, at this time, cannot predict the final impacts on their results of operations, financial position, and liquidity.

In June 2025, the EPA issued a proposed rule to repeal all greenhouse gas emissions standards for fossil fuel-fired power plants, including the April 2024 rule.

The EPA expects to issue a final rule in the first half of 2026.

In addition, in February 2026, the EPA issued a final rule rescinding its 2009 Endangerment Finding for greenhouse gas emissions, which was the basis for implementing greenhouse gas emissions standards.

Ameren and Ameren Missouri are assessing the final rule and, at this time, cannot predict the final impacts on their results of operations, financial position, and liquidity.

In April 2024, the EPA revised the MATS by establishing a more stringent standard for emissions of particulate matter, as well as requiring the use of continuous emissions monitoring systems.

Compliance with the revised rule is required by July 2027, with a possible one-year extension if certain conditions are met.

Requests for a stay of the revised rule have been denied by the United States Court of Appeals for the District of Columbia Circuit and the United States Supreme Court.

Arguments regarding the legal merits of the revised rule will be considered by the United States Court of Appeals for the District of Columbia Circuit.

Ameren and Ameren Missouri estimate capital expenditures of approximately $ 320 million may be necessary to comply with the final rule assuming it is not revised or overturned.

Ameren and Ameren Missouri are monitoring the legal challenges and, at this time, cannot predict the final impacts on their results of operations, financial position, and liquidity.

In November 2024, the EPA issued a proposed rule revising the NSPS to limit emissions of NO x from natural gas-fired stationary CTs.

If adopted as proposed, the rule would require such natural gas facilities which began construction after December 13, 2024, to install certain pollution control equipment to limit emissions of NO x .

In addition, the EPA proposed to maintain the current limits for SO 2 at such natural gas facilities.

Ameren and Ameren Missouri cannot predict the potential impacts of any such rule on their results of operations, financial position, and liquidity until a final rule is adopted.

In April 2025, the presidential administration issued a proclamation through which it granted owners of coal-fired energy centers, including Ameren Missouri, a two-year extension of the compliance deadline.

As such, the compliance deadline for the Labadie and Sioux energy centers is now set for July 2029.

In June 2025, the EPA issued a proposed rule to repeal the April 2024 revisions to the MATS.

The EPA expects to issue a final rule in 2026.

In January 2026, the EPA issued a final rule that established NO x emission standards for several subcategories of natural gas-fired stationary CTs that began construction after December 13, 2024, based on size, utilization, design efficiency, and fuel type.

Ameren and Ameren Missouri are assessing the final rule and, at this time, cannot predict the final impacts on their results of operations, financial position, and liquidity.

NSR and Clean Air Act Litigation

In January 2011, the United States Department of Justice, on behalf of the EPA, filed a complaint against Ameren Missouri in the United States District Court for the Eastern District of Missouri alleging that projects performed in 2007 and 2010 at the coal-fired Rush Island Energy Center violated provisions of the Clean Air Act and Missouri law.

In January 2017, the district court issued a liability ruling against Ameren Missouri and, in September 2019, entered a remedy order that required Ameren Missouri to install a flue gas desulfurization system at the Rush Island Energy Center.

In September 2023, the district court modified the remedy order to allow the early retirement of the Rush Island Energy Center in lieu of installing a flue gas desulfurization system.

Ameren Missouri retired the Rush Island Energy Center on

October 15, 2024.

In December 2024, the United States District Court for the Eastern District of Missouri issued an order resolving all outstanding claims in this case.

The order requires Ameren Missouri to fund a program to provide electric buses and charging stations to schools in the metro St.

Louis area and a program to provide air purifiers to eligible Ameren Missouri electric residential customers.

These programs are estimated to cost approximately $ 64 million.

As of December 31, 2024, Ameren and Ameren Missouri each recorded liabilities of $ 40 million and $ 24 million in “Other current liabilities” and “Other deferred credits and liabilities”, respectively, on their consolidated balance sheets and recorded charges of $ 59 million in “Other operations and maintenance” on their consolidated statements of income in 2024 related to the cost of these programs.

In connection with the accelerated retirement of the Rush Island Energy Center, the MoPSC issued an order in June 2024 authorizing Ameren Missouri to finance the costs associated with the retirement, including the remaining unrecovered net plant balance associated with the facility, through the issuance of securitized utility tariff bonds pursuant to Missouri’s securitization statute.

Costs associated with the retirement exclude any additional mitigation relief ordered in the NSR and Clean Air Act litigation discussed above.

The securitized tariff bonds were issued in December 2024.

See Note 2 – Rate and Regulatory Matters for additional information.

In December 2024, the United States District Court for the Eastern District of Missouri issued an order resolving all outstanding claims related to a complaint filed against Ameren Missouri by the United States Department of Justice that alleged certain projects performed at the coal-fired Rush Island Energy Center violated provisions of the Clean Air Act.

The order requires Ameren Missouri to fund a program to provide electric buses and charging stations to schools within its service territory and a program to provide air purifiers to eligible electric residential customers.

Ameren and Ameren Missouri each had liabilities of $ 36 million in “Other current liabilities” on their consolidated balance sheets as of December 31, 2025 and had liabilities of $ 40 million and $ 24 million in “Other current liabilities” and “Other deferred credits and liabilities”, respectively, on their consolidated balance sheets as of December 31, 2024.

In addition, Ameren and Ameren Missouri each recorded charges of $ 59 million in “Other operations and maintenance” on their consolidated statements of income in 2024 related to the cost of these programs.

Clean Water Act

Among other items, the Clean Water Act requires power plant operators to evaluate cooling water intake structures and identify measures for reducing the number of aquatic organisms impinged on a power plant’s cooling water intake screens or entrained through the plant’s cooling water system.

All of Ameren Missouri’s coal-fired and nuclear energy centers are subject to this cooling water intake structures rule.

Requirements of the rule are implemented by state regulators through the permit renewal process of each power plant’s water discharge permit.

All of Ameren Missouri’s coal-fired and nuclear energy centers are subject to Clean Water Act requirements to identify measures for reducing the number of aquatic organisms impinged on a power plant’s cooling water intake screens or entrained through the plant’s cooling water system.

Cooling water intake requirements are implemented by state regulators through the permit renewal process of each power plant’s water discharge permit.

Permits for Ameren Missouri’s coal-fired and nuclear energy centers have been issued or are in the process of renewal.

In April 2024, the EPA issued new effluent limitation guidelines that established a zero discharge limit for flue gas desulfurization wastewater, bottom ash transport water, and combustion residual leachate.

Ameren and Ameren Missouri expect the impacts of the new guidelines on their results of operations, financial position, and liquidity to be immaterial.

CCR Management

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In April 2024, the EPA revised the CCR Rule to impose groundwater monitoring, and corrective action, closure, and post-closure requirements on certain active and inactive CCR surface impoundments and disposal units not previously included in the 2015 CCR Rule.

Ameren and Ameren Missouri have AROs of $ 46 million associated with CCR storage facilities recorded on their respective balance sheets as of December 31, 2024.

Ameren and Ameren Missouri had AROs of $ 56 million associated with CCR storage facilities recorded on their respective balance sheets as of December 31, 2025.

This amount includes an immaterial incremental ARO related to the 2024 CCR Rule, which may be revised as additional site studies are performed.

Ameren and Ameren Missouri are assessing the impacts of this rule revision and, at this time, cannot predict the final impacts on their results of operations, financial position, and liquidity.

The EPA could reconsider aspects of the 2015 and 2024 CCR rules.

Ameren and Ameren Missouri are monitoring the ongoing legal challenges and regulatory developments but, at this time, cannot predict the final impacts of the 2024 CCR Rule on their results of operations, financial position, and liquidity.

The Ameren Companies are involved in a number of remediation actions to clean up sites impacted by the use or disposal of materials containing hazardous substances.

2 unchanged sentences

Ameren and Ameren Illinois recorded a liability of $ 45 million to represent the estimated minimum obligation for these sites, as no other amount within the range was a better estimate.

Ameren cannot estimate the completion date of the estimated remaining obligation due to site accessibility, among other things.

Ameren and Ameren Illinois cannot estimate the completion dates of the estimated remaining obligation due to site accessibility, among other things.

The scope of the remediation activities at these former MGP sites may increase as remediation efforts continue.

3 unchanged sentences

Our operations or those of our predecessor companies involve the use of, disposal of, and, in appropriate circumstances, the cleanup of substances regulated under environmental laws.

We are unable to determine whether such historical practices will result in future

environmental commitments, including additional or more stringent cleanup standards, or will affect our results of operations, financial position, or liquidity.

Such historical practices may result in future environmental commitments, including additional or more stringent cleanup standards.

We are unable to determine whether such historical practices will affect our results of operations, financial position, or liquidity.

Illinois Emission Standards

Currently as required by the CEJA, Ameren Missouri's natural gas-fired energy centers in Illinois are subject to annual limits on emissions, including CO 2 and NO x .

Further reductions to emissions limits will become effective between 2030 and 2040, resulting in the closure of the Venice Energy Center by the end of 2029.

Further reductions to emissions limits will become effective between 2030 and 2040, resulting in the possible closure of the Venice Energy Center by the end of 2029.

The reductions could also limit the operations of Ameren Missouri's four other natural gas-fired energy centers located in the state of Illinois and will result in their closure by 2040.

14 unchanged sentences

Total cash, cash equivalents, and restricted cash $ 420 $ 68 $ 344 $ 328 $ 17 $ 302

Restricted cash included in “Other current assets” represents funds held by an irrevocable Voluntary Employee Beneficiary Association (VEBA) trust, which provides health care benefits for active employees on Ameren’s, Ameren Missouri’s, and Ameren Illinois’ balance sheets, funds held in an escrow account for programs established as a result of a 2024 court order resolving outstanding claims in the NSR and Clean Air Act litigation on Ameren’s and Ameren Missouri’s balance sheets, and AMF’s restricted cash for payments for securitized utility tariff bonds on Ameren’s and Ameren Missouri’s balance sheets.

Restricted cash included in “Other assets” on Ameren’s and Ameren Illinois’ balance sheets primarily represents amounts collected under a cost recovery rider restricted for use in the procurement of renewable energy credits and amounts in a trust fund restricted for the use of funding certain asbestos-related claims.

15 unchanged sentences

The land leases are related to the Cass County, Boomtown, and Huck Finn energy centers.

See Note 2 – Rate and Regulatory Matters for additional information on the acquisitions.

Rail cars are leased for the transportation of coal to its energy centers.

2 unchanged sentences

Termination and renewal options are not expected to be exercised and are not included in any of the lease measurements used to record the leased assets and liabilities in the tables below.

The following table provides supplemental balance sheet information related to operating leases as of December 31, 2024:

Ameren Ameren Missouri

The following table provides supplemental balance sheet information related to operating leases as of December 31, 2025 and 2024:

December 31, 2025 December 31, 2024

Ameren Ameren Missouri Ameren Ameren Missouri

Other assets $ 76 $ 70 $ 72 $ 69

1 unchanged sentence

Other deferred credits and liabilities 73 68 67 65

Weighted average remaining operating lease term 29 years 30 years

Weighted average remaining operating lease term 28 years 29 years 29 years 30 years

Weighted average discount rate (a)

5.3 % 5.3 % 5.3 % 5.3 %

(a) As an implicit rate is not readily determinable under most of our lease agreements, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments.

37 unchanged sentences

(d) Accretion expense attributable to Ameren Missouri was recorded as a decrease to regulatory liabilities.

(e) The balance as of December 31, 2024, included an ARO related to the decommissioning of the Callaway Enter Center of $ 648 million.

(e) The balance included an ARO related to the decommissioning of the Callaway Enter Center of $ 678 million and $648 million as of December 31, 2025 and 2024, respectively.

Deferred Compensation

36 unchanged sentences

272.2 267.4 263.4

(a) There was an immaterial number of anti-dilutive securities excluded from the earnings per diluted share calculations for the years ended December 31, 2024, 2023, and 2022 related to performance share units and restricted stock units.

Outstanding forward sale agreements as of December 31, 2024 that were anti-dilutive for the year ended December 31, 2024 were excluded from the earnings per diluted share calculation as calculated using the treasury stock method.

(a) There was an immaterial number of anti-dilutive securities excluded from the earnings per diluted share calculations as calculated using the treasury stock method for the years ended December 31, 2025, 2024, and 2023 related to performance share units and restricted stock units.

Outstanding forward sale agreements as of December 31, 2025 and 2024 that were anti-dilutive for the years ended December 31, 2025 and 2024, respectively, were excluded from the earnings per diluted share calculation as calculated using the treasury stock method.

The outstanding forward sale agreements as of December 31, 2023, were anti-dilutive for the year ended December 31, 2023, and excluded from the earnings per diluted share calculation as calculated using the treasury stock method.

38 unchanged sentences

An intersegment elimination at Ameren and Ameren Illinois occurs to eliminate these transmission revenues and expenses.

The CODMs for Ameren, Ameren Missouri, and Ameren Illinois are the Chief Executive Officer of Ameren and Chief Financial Officer of Ameren.

The CODMs for Ameren, Ameren Missouri, and Ameren Illinois are the Chief Executive Officer of Ameren, the Group President of Ameren Utilities of Ameren, and the Chief Financial Officer of Ameren.

The CODMs use net income to evaluate income generated from the segments to make decisions about resources allocated to each segment and assess segment performance.

2 unchanged sentences

Ameren, Ameren Missouri, and Ameren Illinois management review segment capital expenditure information rather than any individual or total asset amount.

Reportable Segments

Ameren Missouri Ameren Illinois Electric Distribution Ameren Illinois Natural Gas Ameren Transmission Other Intersegment Eliminations Ameren

19 unchanged sentences

Capital expenditures 2,502 635 283 717 8 ( 17 ) 4,128

Ameren Missouri Ameren Illinois Electric Distribution Ameren Illinois Natural Gas Ameren Transmission Other Intersegment Eliminations Ameren

External revenues $ 3,960 $ 2,088 $ 938 $ 637 $ — $ — $ 7,623

18 unchanged sentences

Capital expenditures 2,712 579 264 758 7 ( 1 ) 4,319

Reportable Segments

Ameren Missouri Ameren Illinois Electric Distribution Ameren Illinois Natural Gas Ameren Transmission Other Intersegment Eliminations Ameren

External revenues $ 3,825 $ 2,217 $ 897 $ 561 $ — $ — $ 7,500

22 unchanged sentences

Ameren Illinois

Reportable Segments

Ameren Illinois Electric Distribution Ameren Illinois

38 unchanged sentences

Capital expenditures 579 264 624 — 1,467

Reportable Segments

Ameren Illinois Electric Distribution Ameren Illinois

63 unchanged sentences

(a) The following table presents increases/(decreases) in revenues from alternative revenue programs and other revenues not from contracts with customers for the years ended December 31, 2025, 2024, and 2023:

Ameren Missouri Ameren Illinois Electric Distribution Ameren Illinois Natural Gas Ameren Transmission Ameren

Ameren Missouri Ameren Illinois Electric Distribution Ameren Illinois Natural Gas Ameren Transmission Intersegment Eliminations Ameren

Revenues from alternative revenue programs $ ( 5 ) $ ( 135 ) $ ( 34 ) $ ( 26 ) $ — $ ( 200 )

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Other revenues not from contracts with customers 7 (a)

10 2 — — 19 (a)

Revenues from alternative revenue programs $ ( 5 ) $ 116 $ 49 $ 19 $ — $ 179

Other revenues not from contracts with customers ( 103 ) (a)(b)

6 3 — ( 94 ) (a)(b)

Other revenues not from contracts with customers ( 9 ) (a)

7 2 — — — (a)

(a) Includes net realized gains and losses on derivative power contracts.

(b) Includes $ 10 million for insurance recoveries related to lost sales associated with the Callaway Energy Center maintenance outage for the year ended December 31, 2022.

Ameren Illinois

28 unchanged sentences

Compared sentence by sentence after normalising whitespace, quotation marks, case and digits, so re-formatting and restated figures do not read as changed language. Wording changes appear as one removal and one addition. The current filing and the prior one are authoritative.

What changed 10-K

Item 8. Financial Statements and Supplementary Data