Form 8-K

8-K — AMEREN CORP

Accession: 0001104659-26-078317

Filed: 2026-06-26

Period: 2026-06-26

CIK: 0001002910

SIC: 4931 (ELECTRIC & OTHER SERVICES COMBINED)

Item: Other Events

Documents

8-K — tm2619084d1_8k.htm (Primary)

XML — IDEA: XBRL DOCUMENT (R1.htm)

8-K — FORM 8-K

8-K (Primary)

Filename: tm2619084d1_8k.htm · Sequence: 1

false

0001002910

0000100826

false

8-K

2026-06-26

false

0001002910

2026-06-26

0001002910

AEE:UnionElectricCompanyMember

2026-06-26

iso4217:USD

xbrli:shares

iso4217:USD

xbrli:shares

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of

the

Securities Exchange Act of 1934

Date of report (Date of earliest event reported): June 26, 2026

Commission File Number

Exact

Name of Registrant as

Specified in Charter;

State of Incorporation;

Address and Telephone Number

IRS Employer

Identification Number

1-14756

Ameren

Corporation

(Missouri

Corporation)

1901

Chouteau Avenue

St.

Louis, Missouri

63103

(314)

621-3222

43-1723446

1-2967

Union Electric Company

(Missouri Corporation)

1901 Chouteau Avenue

St. Louis, Missouri 63103

(314)

621-3222

43-0559760

Check

the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrants

under any of the following provisions:

¨ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

¨ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

¨ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

¨ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered

pursuant to Section 12(b) of the Act:

Title

of each class

Trading

Symbol(s)

Name

of each exchange on which registered

Common

Stock, $0.01 par value per share

AEE

New

York Stock Exchange

Indicate by check mark whether the registrant

is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2

of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company

Ameren Corporation

Union Electric Company

an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying

with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.

Ameren Corporation

Union Electric Company

Co-Registrant

CIK

0000100826

Co-Registrant

Amendment Flag

false

Co-Registrant

Form Type

8-K

Co-Registrant

DocumentperiodEndDate

2026-02-27

Co-Registrant

Written Commuunications

false

Co-Registrant

Solicitating Materials

false

Co-Registrant

PreCommencement Tender Offer

false

Co-Registrant

PreCommencement Tender Offer

false

Co-Registrant

Entity PreCommencement Issuer Tender Offer

false

ITEM 8.01 Other Events.

On June 26, 2026, Union Electric Company, doing business as Ameren

Missouri (“Ameren Missouri”), filed a request with the Missouri Public Service Commission (“MoPSC”) seeking approval

to increase its annual revenues for electric service by $343 million. The electric rate request is based on a 10.25% return on common

equity, a capital structure composed of 52% common equity, a rate base of $16.7 billion, and a test year ended March 31, 2026, with certain

pro-forma adjustments expected through an anticipated true-up date of December 31, 2026. Ameren Missouri also requested continued use

of the fuel adjustment clause and trackers, including trackers for pension and postretirement benefits, certain excess deferred income

taxes, and the utilization of production and investment tax credits or proceeds from the sale of tax credits, which the MoPSC previously

authorized in earlier electric rate orders. The electric rate request reflects the following:

· increased transmission and distribution infrastructure investments to ensure system reliability and resiliency;

· investments in existing generation resources and 400 megawatts of new generation resources; and

· decreased costs related to accelerating the return to customers of investment tax credits.

The MoPSC proceeding relating to the proposed electric service rate

changes will take place over a period of up to 11 months, with a decision by the MoPSC expected by May 2027 and new rates effective by

June 2027. Ameren Missouri cannot predict the level of any electric service rate change the MoPSC may approve, whether the requested regulatory

recovery mechanisms will be continued, or whether any rate change that may eventually be approved will be sufficient for Ameren Missouri

to recover its costs and earn a reasonable return on its investments when any rate change goes into effect.

This combined Form 8-K is being filed separately by Ameren Corporation

and Union Electric Company (each a “registrant”). Information contained herein relating to any individual registrant has been

filed by such registrant on its own behalf. No registrant makes any representation as to information relating to any other registrant.

SIGNATURES

Pursuant to the requirements of the Securities

Exchange Act of 1934, each registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

The signature for each undersigned company shall be deemed to relate only to matters having reference to such company or its subsidiaries.

AMEREN CORPORATION

(Registrant)

By:

/s/ Leonard P. Singh

Name:

Leonard P. Singh

Title:

Executive Vice President and Chief Financial Officer

UNION ELECTRIC COMPANY

(Registrant)

By:

/s/ Aaron P. Melda

Name:

Aaron P. Melda

Title:

Chairman and President

Date: June 26, 2026

XML — IDEA: XBRL DOCUMENT

XML

Filename: R1.htm · Sequence: 7

v3.26.1

Cover

Jun. 26, 2026

Entity Information [Line Items]

Document Type

8-K

Amendment Flag

false

Document Period End Date

Jun. 26, 2026

Entity File Number

1-14756

Entity Registrant Name

Ameren

Corporation

Entity Central Index Key

0001002910

Entity Tax Identification Number

43-1723446

Entity Incorporation, State or Country Code

Entity Address, Address Line One

1901

Chouteau Avenue

Entity Address, City or Town

St.

Louis

Entity Address, State or Province

Entity Address, Postal Zip Code

63103

City Area Code

314

Local Phone Number

621-3222

Written Communications

false

Soliciting Material

false

Pre-commencement Tender Offer

false

Pre-commencement Issuer Tender Offer

false

Title of 12(b) Security

Common

Stock, $0.01 par value per share

Trading Symbol

AEE

Security Exchange Name

NYSE

Entity Emerging Growth Company

false

Union Electric Company [Member]

Entity Information [Line Items]

Document Type

8-K

Amendment Flag

false

Document Period End Date

Jun. 26, 2026

Entity File Number

1-2967

Entity Registrant Name

Union Electric Company

Entity Central Index Key

0000100826

Entity Tax Identification Number

43-0559760

Entity Incorporation, State or Country Code

Entity Address, Address Line One

1901 Chouteau Avenue

Entity Address, City or Town

St. Louis

Entity Address, State or Province

Entity Address, Postal Zip Code

63103

City Area Code

314

Local Phone Number

621-3222

Written Communications

false

Soliciting Material

false

Pre-commencement Tender Offer

false

Pre-commencement Issuer Tender Offer

false

Entity Emerging Growth Company

false

- Definition

Boolean flag that is true when the XBRL content amends previously-filed or accepted submission.

+ References

No definition available.

+ Details

Name:

dei_AmendmentFlag

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Area code of city

+ References

No definition available.

+ Details

Name:

dei_CityAreaCode

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

For the EDGAR submission types of Form 8-K: the date of the report, the date of the earliest event reported; for the EDGAR submission types of Form N-1A: the filing date; for all other submission types: the end of the reporting or transition period. The format of the date is YYYY-MM-DD.

+ References

No definition available.

+ Details

Name:

dei_DocumentPeriodEndDate

Namespace Prefix:

dei_

Data Type:

xbrli:dateItemType

Balance Type:

Period Type:

duration

- Definition

The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'.

+ References

No definition available.

+ Details

Name:

dei_DocumentType

Namespace Prefix:

dei_

Data Type:

dei:submissionTypeItemType

Balance Type:

Period Type:

duration

- Definition

Address Line 1 such as Attn, Building Name, Street Name

+ References

No definition available.

+ Details

Name:

dei_EntityAddressAddressLine1

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Name of the City or Town

+ References

No definition available.

+ Details

Name:

dei_EntityAddressCityOrTown

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Code for the postal or zip code

+ References

No definition available.

+ Details

Name:

dei_EntityAddressPostalZipCode

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Name of the state or province.

+ References

No definition available.

+ Details

Name:

dei_EntityAddressStateOrProvince

Namespace Prefix:

dei_

Data Type:

dei:stateOrProvinceItemType

Balance Type:

Period Type:

duration

- Definition

A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b-2

+ Details

Name:

dei_EntityCentralIndexKey

Namespace Prefix:

dei_

Data Type:

dei:centralIndexKeyItemType

Balance Type:

Period Type:

duration

- Definition

Indicate if registrant meets the emerging growth company criteria.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b-2

+ Details

Name:

dei_EntityEmergingGrowthCompany

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Commission file number. The field allows up to 17 characters. The prefix may contain 1-3 digits, the sequence number may contain 1-8 digits, the optional suffix may contain 1-4 characters, and the fields are separated with a hyphen.

+ References

No definition available.

+ Details

Name:

dei_EntityFileNumber

Namespace Prefix:

dei_

Data Type:

dei:fileNumberItemType

Balance Type:

Period Type:

duration

- Definition

Two-character EDGAR code representing the state or country of incorporation.

+ References

No definition available.

+ Details

Name:

dei_EntityIncorporationStateCountryCode

Namespace Prefix:

dei_

Data Type:

dei:edgarStateCountryItemType

Balance Type:

Period Type:

duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:

dei_EntityInformationLineItems

Namespace Prefix:

dei_

Data Type:

xbrli:stringItemType

Balance Type:

Period Type:

duration

- Definition

The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b-2

+ Details

Name:

dei_EntityRegistrantName

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b-2

+ Details

Name:

dei_EntityTaxIdentificationNumber

Namespace Prefix:

dei_

Data Type:

dei:employerIdItemType

Balance Type:

Period Type:

duration

- Definition

Local phone number for entity.

+ References

No definition available.

+ Details

Name:

dei_LocalPhoneNumber

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 13e

-Subsection 4c

+ Details

Name:

dei_PreCommencementIssuerTenderOffer

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 14d

-Subsection 2b

+ Details

Name:

dei_PreCommencementTenderOffer

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Title of a 12(b) registered security.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b

+ Details

Name:

dei_Security12bTitle

Namespace Prefix:

dei_

Data Type:

dei:securityTitleItemType

Balance Type:

Period Type:

duration

- Definition

Name of the Exchange on which a security is registered.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection d1-1

+ Details

Name:

dei_SecurityExchangeName

Namespace Prefix:

dei_

Data Type:

dei:edgarExchangeCodeItemType

Balance Type:

Period Type:

duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as soliciting material pursuant to Rule 14a-12 under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 14a

-Subsection 12

+ Details

Name:

dei_SolicitingMaterial

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Trading symbol of an instrument as listed on an exchange.

+ References

No definition available.

+ Details

Name:

dei_TradingSymbol

Namespace Prefix:

dei_

Data Type:

dei:tradingSymbolItemType

Balance Type:

Period Type:

duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as written communications pursuant to Rule 425 under the Securities Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Securities Act

-Number 230

-Section 425

+ Details

Name:

dei_WrittenCommunications

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Details

Name:

dei_LegalEntityAxis=AEE_UnionElectricCompanyMember

Namespace Prefix:

Data Type:

Balance Type:

Period Type: