Commitments And Contingencies	6 Months Ended
Jun. 30, 2026
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES We are involved in legal, tax, and regulatory proceedings before various courts, regulatory commissions, authorities, and governmental agencies with respect to matters that arise in the ordinary course of business, some of which involve substantial amounts of money. We believe that the final disposition of these proceedings, except as otherwise disclosed in the notes to our financial statements in this report and in the Form 10-K, will not have a material adverse effect on our results of operations, financial position, or liquidity. Reference is made to Note 1 – Summary of Significant Accounting Policies, Note 2 – Rate and Regulatory Matters, Note 9 – Callaway Energy Center, Note 13 – Related-party Transactions, and Note 14 – Commitments and Contingencies under Part II, Item 8, of the Form 10-K. See also Note 1 – Summary of Significant Accounting Policies, Note 2 – Rate and Regulatory Matters, Note 8 – Related-party Transactions, and Note 10 – Callaway Energy Center of this report. Environmental Matters Our electric generation, transmission, and distribution and natural gas distribution and storage operations must comply with a variety of statutes and regulations relating to the protection of the environment and human health and safety, including permitting programs implemented by federal, state, and local authorities. Such environmental laws regulate air emissions; protect water bodies; 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 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 SO2, particulate matter, NOx, mercury, toxic metals and acid gases, and CO2 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 implementation of corrective measures if necessary. The combined effects of compliance with existing and future environmental regulations and permitting 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 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 nighttime operating curtailments will have a material impact on its results of operations, financial position, or liquidity. In March 2026, Ameren Missouri submitted an application to the United States Fish and Wildlife Service for a new 30-year federal permit to operate the High Prairie Energy Center. Ameren Missouri’s current permit expires in May 2027. Ameren and Ameren Missouri cannot predict when, or if, the permit application will be approved by the United States Fish and Wildlife Service. Ameren and Ameren Missouri anticipate they may need to make estimated capital expenditures of $70 million to $100 million from 2026 through 2030 to comply with environmental regulations. Additional capital expenditures beyond 2030 could be required. This estimate includes surface impoundment closure and corrective action measures required by the 2015 and 2024 CCR rules and modifications to cooling water intake structures at existing power plants under Clean Water Act rules, 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 in Note 14 – Commitments and Contingencies under Part II, Item 8, of the Form 10-K, 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 could ultimately revise all or part of such federal regulations. Clean Air Act Federal and state laws, including the CSAPR, regulate emissions of SO2 and NOx 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 NOx allowances available for compliance. In January 2026, the EPA issued a proposed rule to reconsider the Good Neighbor Rule which, if finalized as proposed, would resolve underlying litigation involving numerous states including Missouri. 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 NOx air pollution control equipment. If a final rule is issued similar to the proposed rule, Ameren Missouri would not expect additional NOx controls at its coal-fired energy centers to be necessary. CO2 Emissions Standards In 2024, the EPA issued a final rule that sets CO2 emission standards for existing coal-fired and new natural gas-fired power plants based on the emissions expected from adoption of carbon capture technology and/or natural gas co-firing for coal-fired power plants and carbon capture technology for new natural gas-fired power plants. Affected power plants are required to comply with the rule through a phased-in approach or retire. In 2025, the EPA issued a proposed rule to repeal all greenhouse gas emissions standards for fossil fuel-fired power plants, including the 2024 rule. The EPA expects to issue a final rule by the end of 2026. In addition, in February 2026, the EPA issued a final rule to rescind its 2009 Greenhouse Gas Endangerment Finding, which was the basis for implementing greenhouse gas emissions standards. Litigation regarding the rescission of the 2009 Greenhouse Gas Endangerment Finding is ongoing. Ameren and Ameren Missouri are assessing the final rule and, at this time, cannot predict the impacts of the final rule on their results of operations, financial position, and liquidity. MATS In February 2026, the EPA issued a final rule repealing a 2024 rule that had revised the MATS and established more stringent standards for emissions of particulate matter and mercury and required the use of continuous emissions monitoring systems. As a result of the repeal, the 2024 rule will not impact Ameren’s and Ameren Missouri’s results of operations, financial position, and liquidity. NSPS In January 2026, the EPA issued a final rule that established NOx emission standards for several subcategories of stationary CTs that began construction after mid-December 2024, based on size, utilization, design efficiency, and fuel type. Ameren and Ameren Missouri do not expect the final rule to materially impact their results of operations, financial position, and liquidity. Clean Water Act 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. CCR Management The EPA’s 2015 CCR Rule establishes requirements for the management and disposal of CCR from coal-fired power plants and has resulted in the closure of surface impoundments at Ameren Missouri’s energy centers, with closures of two surface impoundments in process at its retired Meramec Energy Center as a part of the construction of the Castle Bluff Natural Gas Project. Ameren Missouri’s CCR management compliance plan includes installation of groundwater monitoring equipment and groundwater treatment facilities. In 2024, the EPA revised the CCR Rule to include certain active and inactive CCR surface impoundments and disposal units not previously included in the 2015 CCR Rule. Ameren and Ameren Missouri recorded AROs of $57 million associated with CCR storage facilities on their respective balance sheets as of June 30, 2026. This amount includes an immaterial incremental ARO related to the 2024 CCR Rule, which may be revised as additional site studies are performed. In April 2026, the EPA issued a proposed rule that reconsiders aspects of the 2015 and 2024 CCR rules and proposes various amendments and compliance alternatives. Ameren and Ameren Missouri are monitoring the ongoing regulatory developments but, at this time, cannot predict the final impacts of the CCR rules or the EPA’s proposed revisions on their results of operations, financial position, and liquidity. Remediation 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. Federal and state laws can require responsible parties to fund remediation regardless of their degree of fault, the legality of original disposal, or the ownership of a disposal site. As of June 30, 2026, Ameren Illinois has remediated the majority of the 44 former MGP sites in Illinois with an estimated remaining obligation primarily related to three of these former MGP sites at $45 million to $90 million. 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 and Ameren Illinois cannot estimate the completion dates of the estimated remaining obligation or the scope of any future remediation due to site accessibility, among other things. Considerable uncertainty remains in these estimates because many site-specific factors can influence the actual costs, including unanticipated underground structures, the degree to which groundwater is impacted, regulatory changes, local ordinances, and site accessibility. The actual costs and timing of completion may vary substantially from these estimates. The ICC allows Ameren Illinois to recover MGP remediation and related litigation costs from its electric and natural gas utility customers through environmental cost riders that are subject to annual prudence reviews by the ICC. 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. 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.

We are involved in legal, tax, and regulatory proceedings before various courts, regulatory commissions, authorities, and governmental agencies with respect to matters that arise in the ordinary course of business, some of which involve substantial amounts of money. We believe that the final disposition of these proceedings, except as otherwise disclosed in the notes to our financial statements in this report and in the Form 10-K, will not have a material adverse effect on our results of operations, financial position, or liquidity.

Reference is made to Note 1 – Summary of Significant Accounting Policies, Note 2 – Rate and Regulatory Matters, Note 9 – Callaway Energy Center, Note 13 – Related-party Transactions, and Note 14 – Commitments and Contingencies under Part II, Item 8, of the Form 10-K. See also Note 1 – Summary of Significant Accounting Policies, Note 2 – Rate and Regulatory Matters, Note 8 – Related-party Transactions, and Note 10 – Callaway Energy Center of this report.

Our electric generation, transmission, and distribution and natural gas distribution and storage operations must comply with a variety of statutes and regulations relating to the protection of the environment and human health and safety, including permitting programs implemented by federal, state, and local authorities. Such environmental laws regulate air emissions; protect water bodies; 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 and hazardous materials require release prevention plans and emergency response procedures.

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 SO2, particulate matter, NOx, mercury, toxic metals and acid gases, and CO2 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 implementation of corrective measures if necessary. The combined effects of compliance with existing and future environmental regulations and permitting 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 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 nighttime operating curtailments will have a material impact on its results of operations, financial position, or liquidity. In March 2026, Ameren Missouri submitted an application to the United States Fish and Wildlife Service for a new 30-year federal permit to operate the High Prairie Energy Center. Ameren Missouri’s current permit expires in May 2027. Ameren and Ameren Missouri cannot predict when, or if, the permit application will be approved by the United States Fish and Wildlife Service.

Ameren and Ameren Missouri anticipate they may need to make estimated capital expenditures of $70 million to $100 million from 2026 through 2030 to comply with environmental regulations. Additional capital expenditures beyond 2030 could be required. This estimate includes surface impoundment closure and corrective action measures required by the 2015 and 2024 CCR rules and modifications to cooling water intake structures at existing power plants under Clean Water Act rules, 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 in Note 14 – Commitments and Contingencies under Part II, Item 8, of the Form 10-K, 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.

Federal and state laws, including the CSAPR, regulate emissions of SO2 and NOx 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 NOx allowances available for compliance. In January 2026, the EPA issued a proposed rule to reconsider the Good Neighbor Rule which, if finalized as proposed, would resolve underlying litigation involving numerous states including Missouri. 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 NOx air pollution control equipment. If a final rule is issued similar to the proposed rule, Ameren Missouri would not expect additional NOx controls at its coal-fired energy centers to be necessary.

In 2024, the EPA issued a final rule that sets CO2 emission standards for existing coal-fired and new natural gas-fired power plants based on the emissions expected from adoption of carbon capture technology and/or natural gas co-firing for coal-fired power plants and carbon capture technology for new natural gas-fired power plants. Affected power plants are required to comply with the rule through a phased-in approach or retire. In 2025, the EPA issued a proposed rule to repeal all greenhouse gas emissions standards for fossil fuel-fired power plants, including the 2024 rule. The EPA expects to issue a final rule by the end of 2026. In addition, in February 2026, the EPA issued a final rule to rescind its 2009 Greenhouse Gas Endangerment Finding, which was the basis for implementing greenhouse gas emissions standards. Litigation regarding the rescission of the 2009 Greenhouse Gas Endangerment Finding is ongoing. Ameren and Ameren Missouri are assessing the final rule and, at this time, cannot predict the impacts of the final rule on their results of operations, financial position, and liquidity.

In February 2026, the EPA issued a final rule repealing a 2024 rule that had revised the MATS and established more stringent standards for emissions of particulate matter and mercury and required the use of continuous emissions monitoring systems. As a result of the repeal, the 2024 rule will not impact Ameren’s and Ameren Missouri’s results of operations, financial position, and liquidity.

In January 2026, the EPA issued a final rule that established NOx emission standards for several subcategories of stationary CTs that began construction after mid-December 2024, based on size, utilization, design efficiency, and fuel type. Ameren and Ameren Missouri do not expect the final rule to materially impact their results of operations, financial position, and liquidity.

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.

The EPA’s 2015 CCR Rule establishes requirements for the management and disposal of CCR from coal-fired power plants and has resulted in the closure of surface impoundments at Ameren Missouri’s energy centers, with closures of two surface impoundments in process at its retired Meramec Energy Center as a part of the construction of the Castle Bluff Natural Gas Project. Ameren Missouri’s CCR management compliance plan includes installation of groundwater monitoring equipment and groundwater treatment facilities. In 2024, the EPA revised the CCR Rule to include certain active and inactive CCR surface impoundments and disposal units not previously included in the 2015 CCR Rule. Ameren and Ameren Missouri recorded AROs of $57 million associated with CCR storage facilities on their respective balance sheets as of June 30, 2026. This amount includes an immaterial incremental ARO related to the 2024 CCR Rule, which may be revised as additional site studies are performed. In April 2026, the EPA issued a proposed rule that reconsiders aspects of the 2015 and 2024 CCR rules and proposes various amendments and compliance alternatives. Ameren and Ameren Missouri are monitoring the ongoing regulatory developments but, at this time, cannot predict the final impacts of the CCR rules or the EPA’s proposed revisions 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. Federal and state laws can require responsible parties to fund remediation regardless of their degree of fault, the legality of original disposal, or the ownership of a disposal site.

As of June 30, 2026, Ameren Illinois has remediated the majority of the 44 former MGP sites in Illinois with an estimated remaining obligation primarily related to three of these former MGP sites at $45 million to $90 million. 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 and Ameren Illinois cannot estimate the completion dates of the estimated remaining obligation or the scope of any future remediation due to site accessibility, among other things. Considerable uncertainty remains in these estimates because many site-specific factors can influence the actual costs, including unanticipated underground structures, the degree to which groundwater is impacted, regulatory changes, local ordinances, and site accessibility. The actual costs and timing of completion may vary substantially from these estimates.

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. 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.