Ameren Illinois Company (AILIH) is a regulated electric and natural gas utility that delivers electricity and natural gas to customers in Illinois. It makes money by collecting rates approved by state regulators, charging customers for the delivery of electricity and natural gas across its distribution network. Ameren Illinois is a wholly owned subsidiary of Ameren Corporation, with all of its common stock held by the parent as of June 30, 2025. The company files separately with the SEC as its own registrant, as disclosed in the combined Form 10-K filed February 18, 2026 for the fiscal year ended December 31, 2025. Its operations span regulated electric distribution and natural gas distribution in Illinois, subject to oversight by the Illinois Commerce Commission. The business also administers customer energy-efficiency programs and manages natural gas supply for distribution, as noted in the FY2025 10-K filing. Capital structure is characteristic of regulated utilities: rate-base driven, capital-intensive, and dependent on constructive regulatory outcomes for returns.

Revenue model

Regulated utility rate recovery. Revenue is earned by charging customers tariff rates approved by Illinois regulators for the delivery of electricity and natural gas through its distribution infrastructure.

Products and services

Electric distribution service, natural gas distribution service, customer energy-efficiency programs, natural gas supply for distribution.

Customers and end markets

Residential, commercial, and industrial customers in Illinois receiving electric and natural gas distribution service. Specific customer counts are not provided in the available filing excerpts.

Value-chain role

Regulated distribution utility. Delivers electricity and natural gas from transmission systems to end customers; does not generate electricity or produce natural gas based on available filing excerpts.

Geographic exposure

Illinois, United States. Operates as a state-regulated utility under Illinois Commerce Commission jurisdiction.

Source: SEC 10-K, filed 2026-02-18

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