Company: AFGC
Filing Date: 2025-09-17
Form Type: 424B5
Source: 0001140361-25-035246
Chunk: 1

Company: AMERICAN FINANCIAL GROUP INC
Filing Date: 2025-09-17
Form: 424B5
Chunk 1
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 23, 2025, to the date of delivery. |

We expect that the senior notes will be ready for delivery in book-entry form only through the facilities of The Depository Trust Company for the accounts of its participants on or about September 23, 2025. Joint Book-Running Managers

| BofA Securities |     | J.P. Morgan |     | Wells Fargo Securities |

Co-Managers

| PNC Capital Markets LLC |     | Fifth Third Securities |     | MUFG |     | US Bancorp |

The date of this prospectus supplement September 16, 2025.

#### TABLE OF CONTENTS
**This document consists of two parts. The first part is this prospectus supplement, which describes the specific terms of our offering of the senior notes. The second part is the accompanying prospectus, which forms a part of the registration statement and provides more general information, some of which may not be applicable to this offering. This prospectus supplement and the accompanying prospectus include important information about us, the senior notes and other information you should know before investing in the senior notes. This prospectus supplement also adds, updates and changes information contained in the accompanying prospectus. If there is any inconsistency between the information in this prospectus supplement and the accompanying prospectus, you should rely on the information in this prospectus supplement. You will find additional information about us in the registration statement and in the documents incorporated by reference herein. Any statements made in this prospectus supplement or the accompanying prospectus concerning the provisions of legal documents are not necessarily complete and you should read the documents that are filed as exhibits to the registration statement or otherwise filed with the SEC for a more complete understanding of the document or matter.

Before investing in the senior notes, you should carefully read both this prospectus supplement and the accompanying prospectus, together with the additional information described under “Where You Can Find More Information” and “Incorporation of Certain Documents by Reference” in this prospectus supplement.

You should rely only on the information contained or incorporated by reference in this prospectus supplement and the accompanying prospectus and in any free writing prospectus we authorize that supplements this prospectus supplement. We have not, and the underwriters have not, authorized any other person to provide you with different information or make any representations other than those contained or incorporated by reference in this prospectus supplement. If anyone other than us provides you with different or inconsistent information, you should not rely on it. We take no responsibility for, and can provide no assurance