Here are the 424B prospectus supplements from Ameren Illinois 4.08 PFD (AILIH) in our archive over the last 12 months, newest first, and each one links through to the document itself with the summary and the scores our analysis gives it.
A 424B covers the supplement that carries the terms of a priced offering, so if you follow AILIH and want that one kind of document rather than the whole filing history, this is the page to keep. The company's other filings, of every form, are on the full AILIH filings page.
Ameren Illinois Company (AILIH) is issuing $400,000,000 principal amount of 5.50% First Mortgage Bonds due September 15, 2036 under its shelf registration. The bonds pay interest semi-annually on March 15 and September 15, starting March 15, 2027, and are issued at 99.988% of principal in $2,000 minimum denominations.
The bonds are secured by a first lien under Ameren Illinois’ mortgage indenture, ranking equally with its other first mortgage bonds and effectively ahead of unsecured debt. As of June 30, 2026, first mortgage bonds outstanding totaled about $6.3 billion and unsecured short‑term debt was about $428 million, with capacity to issue additional first mortgage bonds.
Ameren Illinois expects gross proceeds of $399.952 million, underwriting discounts of $2.6 million and net proceeds of about $395.6 million, to be used primarily to repay commercial paper short‑term debt of approximately $470.9 million bearing a 3.86% weighted‑average rate as of August 14, 2026. The bonds are callable: before June 15, 2036 at a make‑whole premium based on a Treasury Rate plus 15 bps, and on or after that date at 100% of principal, in each case plus accrued interest. If a defined Tax Credit Event occurs, Ameren Illinois may redeem all bonds at 101% of principal plus accrued interest. No exchange listing is expected.
Ameren Illinois Company plans to issue a new series of first mortgage bonds due 2036 under its existing mortgage indenture. The bonds will pay semiannual interest and be issued in minimum $2,000 denominations, in book-entry form through DTC, Clearstream and Euroclear.
The bonds will be secured by a first lien on substantially all Ameren Illinois properties, ranking equally with its other first mortgage bonds, effectively senior to unsecured debt and senior to any subordinated obligations. Ameren Illinois may redeem the bonds before maturity at a make-whole premium based on a Treasury Rate, and at par on or after a defined par call date. If a Tax Credit Event occurs related to holdings by specified foreign entities, Ameren Illinois may redeem all bonds at 101% of principal plus accrued interest.
Net proceeds are expected to be used to repay short-term commercial paper borrowings. As of June 30, 2026, total capitalization was $14.7 billion, including $6.3 billion of long-term secured debt and $428 million of short-term debt. The bonds will not be listed on any securities exchange and no trading market currently exists.