Ameren Illinois Co

Overview

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• TickerAILIH on OTC²
• IndustryElectric & Other Services Combined²
• HeadquartersCollinsville, United States²
• Incorporated inIL³
• Business address10 Richard Mark Way, Collinsville, Il 62234³
• Legal formBusiness Corporation²
• LEIRC71E2BZ6UOMFPDJSE79²
• StatusActive²
• LEI statusIssued and current²
• Registered addressC/O THE CORPORATION COMPANY, 62704-2550 Springfield, United States²
• Registered withBusiness Services (Office of the Secretary of State), 17166468²

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Corporate structure

Ameren Illinois Co is part of a group headed by Ameren. 22 entities, 2 countries on record. Switch between the flow chart and the network, and select any entity to see its details.

Built from parent and subsidiary links from GLEIF, the Global Legal Entity Identifier Foundation (CC0); subsidiaries listed in Exhibit 21 of annual reports filed with the SEC; subsidiaries, stakes and holdings from Wikidata (CC0). Each entity in the chart links to its source.

What it owns

What Ameren Illinois Co reports owning in its annual reports to the SEC: buildings, land and equipment, real estate and locations, investments, intangible assets and inventory, at the end of its latest fiscal year and a year before.

Properties, in its own words

For information on our principal properties, see the energy center and in-service utility-related properties tables below. See also Liquidity and Capital Resources and Regulatory Matters in Management’s Discussion and Analysis of Financial Condition and Results of Operations under Part II, Item 7, of this report for a discussion of planned additions. See also Note 14 – Commitments and Contingencies under Part II, Item 8, of this report.

The following table shows the anticipated capability of our energy centers at the time of the expected 2026 peak summer electrical demand for all energy centers owned as of December 31, 2025, except as otherwise noted below:

Item 2 of the 10-K filed Feb 18, 2026.⁴

Leadership

Who has led Ameren Illinois Co, and when. Pick a name to see everywhere that person has worked.

• Chief executive officerRichard J. Mark Jun 25, 2012 to Jun 25, 2012⁵
• PresidentRichard J. Mark Jun 25, 2012 to Jun 25, 2012⁵

Subsidiaries and ownership

Parent company (GLEIF)

• Ameren²

Ownership links from GLEIF, the Global Legal Entity Identifier Foundation (CC0); each one cites its LEI record.

Former names

• CENTRAL ILLINOIS PUBLIC SERVICE COFeb 28, 1994 to Sep 13, 2010³

Timeline

1. Nov 23, 2012Parent Directly consolidated by Ameren²
2. Jun 25, 2012New chief executive Richard J. Mark becomes CEO⁵
3. Sep 1, 1923Founded Ameren Illinois Co is founded²

Filings

32 filings to the SEC since October 2021: 1 insider forms, 31 other. The latest 20:

1. Aug 18, 2026424B2 EDGAR
2. Aug 17, 2026FWP EDGAR
3. Aug 17, 2026424B3 EDGAR
4. Mar 31, 2026DEFA14C EDGAR
5. Mar 31, 2026DEF 14C EDGAR
6. Sep 16, 2025424B2 EDGAR
7. Sep 15, 2025FWP EDGAR
8. Sep 15, 2025424B3 EDGAR
9. Mar 25, 2025DEFA14C EDGAR
10. Mar 25, 2025DEF 14C EDGAR
11. Feb 25, 2025424B2 EDGAR
12. Feb 24, 2025FWP EDGAR
13. Feb 24, 2025424B3 EDGAR
14. Jun 18, 2024424B2 EDGAR
15. Jun 17, 2024FWP EDGAR
16. Jun 17, 2024424B3 EDGAR
17. Apr 5, 2024DEFA14C EDGAR
18. Apr 5, 2024DEF 14C EDGAR
19. May 24, 2023424B2 EDGAR
20. May 23, 2023FWP EDGAR

Every filing from the last five years, summarized. The full record is on SEC EDGAR.

SEC filer profile

How Ameren Illinois Co is registered with the Securities and Exchange Commission, from its EDGAR record and the cover page of its latest annual report.

• Name on EDGARAmeren Illinois Co¹
• CIK0000018654
• Employer ID (EIN)43-1723446⁴
• Filer statusLarge accelerated filer not an emerging growth company; not a smaller reporting company; not a shell company⁴
• Incorporated inMissouri⁴
• Fiscal year endsDecember 31¹
• Industry code (SIC)4931 Electric & Other Services Combined¹
• SEC reviewing officeOffice of Energy & Transportation, Division of Corporation Finance¹
• Business address10 Richard Mark Way, Collinsville, IL 62234¹
• Phone618-343-8150¹
• Shares outstanding276,424,515 shares; 102,123,834 Union Electric Company shares; 25,452,373 Ameren Illinois Company shares as of Jan 30, 2026⁴
• Public float$25.9B as of Jun 30, 2025⁴
• AuditorPricewaterhouseCoopers LLP, St. Louis, Missouri PCAOB ID 238; it also attests to the company’s internal control over financial reporting⁴
• On EDGAR sinceFeb 28, 1994¹
• Filings473 in all: 8-K (135), 10-Q (98), 10-K (30), 424B3 (25), 3 (24), 424B2 (24), DEF 14C (22), FWP (22)¹
  All 35 form types

  DEF 14A (12), DEFA14C (11), 11-K (9), UPLOAD (8), S-3ASR (7), SC 13G/A (5), 424B5 (4), U-3A-2 (4), 10-K405 (3), 10-Q/A (3), S-3 (3), SC 13G (3), 425 (2), ARS (2), CORRESP (2), RW (2), S-4/A (2), U-6B-2 (2), 10-K/A (1), 5 (1), 8-A12G (1), 8-K/A (1), EFFECT (1), PRE 14A (1), S-3/A (1), S-3DPOS (1), S-4 (1)

• Latest filingsAnnual report (10-K) Feb 18, 2026
  Quarterly report (10-Q) Aug 3, 2026
  Proxy statement (DEF 14A) Mar 23, 2004
  Latest 8-K (8-K) Aug 24, 2026

Securities registered for trading

From the cover page of the 10-K filed Feb 18, 2026 (Section 12(b) of the Exchange Act).⁴

Risk factors and legal proceedings

The risks Ameren Illinois Co names in Item 1A of its 10-K filed Feb 18, 2026: 20 risks under these headings, as written.⁴

• REGULATORY AND LEGISLATIVE RISKS
• We are subject to extensive regulation of our businesses.
• The electric and natural gas rates that we are allowed to charge are determined through regulatory proceedings, which are subject to intervention and appeal. Rates are also subject to legislative actions, which are largely outside of our control. Certain events could prevent us from recovering our costs in a timely manner or at all, or from earning adequate returns on our investments.
• Beginning in 2024 through at least 2027, electric distribution rates for Ameren Illinois are established through an MYRP, which are subject to ongoing regulatory and judicial proceedings and associated risks, and are subject to a reconciliation cap.
• As a result of the election to use the PISA, Ameren Missouri’s electric service business is subject to a limitation on increasing the annual revenue requirement due to the inclusion of incremental PISA deferrals in the revenue requirement.
• We are subject to various environmental and permitting laws. Significant capital expenditures may be required to achieve and to maintain compliance with these environmental laws. Failure to comply with these laws could result in the closing of facilities, alterations to the manner in which these facilities operate, increased operating costs, delays and increased costs of building new facilities, and exposure to fines and liabilities.
• We are subject to business and financial risks related to the impact of climate-related legislation, regulation, and emission reduction initiatives.
• We are subject to regulatory compliance and proceedings, which could result in increasing costs, regulatory penalties, and/or other sanctions.
• OPERATIONAL RISKS
• The construction and acquisition of, and capital improvements to, electric and natural gas utility infrastructure, along with Ameren Missouri’s ability to implement its Smart Energy Plan and its 2025 Change to the 2023 PRP, involve substantial risks.
• Our electric generation and electric and natural gas transmission and distribution facilities, including natural gas storage facilities, are subject to operational risks.
• Ameren Missouri’s ability to obtain an adequate supply of coal could limit operation of its coal-fired energy centers.

Legal proceedings

We are involved in legal and administrative proceedings before various courts and 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 this report, will not have a material adverse effect on our results of operations, financial position, or liquidity. Risk of loss is mitigated, in some cases, by insurance or contractual or statutory indemnification. We believe that we have established appropriate reserves for potential losses. For additional information on material legal and administrative proceedings, see Note 2 – Rate and Regulatory Matters, Note 9 – Callaway Energy Center, and Note 14 – Commitments and Contingencies under Part II, Item 8, of this report. Pursuant to Item 103(c)(3)(iii) of Regulation S-K, our policy is to disclose environmental proceedings to which a governmental entity is a party if we reasonably believe such proceedings will result in monetary sanctions of $1 million or more.

The opening of Item 3, Legal Proceedings.⁴