Company: AILIM
Filing Date: 2025-09-16
Form Type: 424B2
Source: 0001104659-25-090464
Chunk: 5

Company: Ameren Illinois Co
Filing Date: 2025-09-16
Form: 424B2
Chunk 5
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/o Ameren Corporation 
 Attention: Office of the Secretary 
 P.O. Box 66149, Mail Code 1310 
 St. Louis, Missouri 63166-6149 
 Telephone: (314) 621-3222

Upon such request, we will provide to each person, including any beneficial owner, to whom this prospectus supplement and the accompanying prospectus are delivered, a copy of all of the information that has been incorporated by reference in this prospectus supplement and the accompanying prospectus but not delivered with this prospectus supplement and the accompanying prospectus. Copies of these filings are also available from Ameren’s website at www.amereninvestors.com. We do not intend for this website to be an active link or to otherwise incorporate the contents of the website into this prospectus supplement or the accompanying prospectus.

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TABLE OF CONTENTS

CAPITALIZATION The following table shows our capitalization (including short-term debt) as of June 30, 2025. As a result of our intended use of net proceeds from the sale of the bonds as described under “Use of Proceeds” in this prospectus supplement, this offering will not have a material effect on our capitalization.

| ​                                                                               | ​ | ​ | As of June 30, 2025 |   |        |   |   |   |                                |   |        |   | ​ |
|:--------------------------------------------------------------------------------|:--|:--|:--------------------|:--|-------:|:--|:--|:--|:-------------------------------|:--|-------:|:--|:--|
| ​                                                                               | ​ | ​ | Amount              |   |        |   | ​ | ​ | Percent ofTotal Capitalization |   |        |   | ​ |
| ​                                                                               | ​ | ​ | -in millions        |   |        |   | ​ | ​ | ​                              | ​ |      ​ | ​ | ​ |
| Short-term debt(1)                                                              | ​ | ​ | ​                   | $ |    245 | ​ | ​ | ​ | ​                              | ​ |   1.8% | ​ | ​ |
| Long-term secured debt (including current maturities)(2)(3)                     | ​ | ​ | ​                   | ​ |  5,963 | ​ | ​ | ​ | ​                              | ​ |   43.0 | ​ | ​ |
| Total short-term debt and long-term