Jefferies Financial Group Inc美股招股说明书(2026-07-07版)

SUBJECT TO COMPLETION, DATED JULY 7, 2026 PRELIMINARY PROSPECTUS SUPPLEMENT(To Prospectus dated May11, 2026) € Jefferies Financial Group Inc.% SENIOR NOTES DUE Jefferies Financial Group Inc. is offering €aggregate principal amount of its% Senior Notes due(the “Notes”). Maturity– The Notes will mature on Interest– We will pay interest on the Notes in cash annually in arrears on Ranking– The Notes will be our senior unsecured obligations and will rank equally with our other senior unsecured indebtedness. Redemption Upon a Tax Event– The Notes are not redeemable by us prior to their maturity except under the circumstances describedunder “Description of the Notes—Redemption Upon a Tax Event.” The Notes will be issued only in registered form in denominations of €100,000 and integral multiples of €1,000 in excess thereof. Investing in the Notes involves risks that are described in the section entitled“Risk Factors”beginning on page S-6of thisprospectus supplement. Plus accrued interest from, 2026, if settlement occurs after that date.(1) Neither the U.S. Securities and Exchange Commission (the “SEC”) nor any state securities commission has approved ordisapproved of these securities or determined if this prospectus supplement or the accompanying prospectus is truthful orcomplete. Any representation to the contrary is a criminal offense. Jefferies Financial Group Inc. may use this prospectus supplement in the initial sale of the Notes. In addition, Jefferies InternationalLimited or any other subsidiary of Jefferies Financial Group Inc. may use this prospectus supplement in a market-making transactionof a Noteafter its initial sale.Unless Jefferies Financial Group Inc. or its agent informs the purchaser otherwise in theconfirmation of sale, this prospectus supplement is being used in a market-making transaction. This prospectus supplement and the accompanying prospectus constitute “listing particulars” (the “Listing Particulars”) for thepurposes of the admission of the Notes on the Official List of the Irish Stock Exchange plc, trading as Euronext Dublin (“EuronextDublin”) and to trading on the Global Exchange Market of Euronext Dublin (the “GEM”). Application is expected to be made for (i)the Listing Particulars to be approved as “listing particulars” by Euronext Dublin and (ii) the Notes to be admitted to the Official Listof Euronext Dublin and traded on the GEM (which is not a regulated market for the purposes of Directive 2014/65/EU, as amended(“MiFID II”)) of Euronext Dublin. The Notes are a new issue of securities with no established trading market. We have no obligationto maintain such listing, and we may delist the Notes at any time. The underwriters expect to deliver the Notes in book-entry form under the New Safekeeping Structure (the “NSS”) through EuroclearBank SA/NV, as operator of the Euroclear System (“Euroclear”), and Clearstream Banking S.A. (“Clearstream”) (together, Euroclearand Clearstream are referred to herein as the “ICSDs”), on or about, 2026 (the “issue date”), which is the fifth business dayfollowing the date of pricing (such settlement cycle being referred to as “T+5”). Upon issuance, the Notes will be represented by aglobal note in registered form (the “Global Note”), which is expected to be deposited with a common safekeeper (“CommonSafekeeper”) for Euroclear and Clearstream and registered in the name of the nominee of the Common Safekeeper. Jefferies Joint Active Book-Runners TABLE OF CONTENTS IMPORTANT NOTICE ABOUT INFORMATION IN THIS PROSPECTUS SUPPLEMENT AND THEACCOMPANYING PROSPECTUSS-iiSPECIAL NOTE ON FORWARD-LOOKING STATEMENTSS-ivPROSPECTUS SUPPLEMENT SUMMARYS-1THE OFFERINGS-3RISK FACTORSS-6CURRENCY CONVERSIONS-9USE OF PROCEEDSS-10CAPITALIZATIONS-11DESCRIPTION OF THE NOTESS-12MATERIAL U.S. FEDERAL INCOME TAX CONSIDERATIONSS-18UNDERWRITINGS-22CONFLICT OF INTERESTS-27LEGAL MATTERSS-28EXPERTSS-28WHERE YOU CAN FIND MORE INFORMATIONS-29INCORPORATION OF CERTAIN INFORMATION BY REFERENCES-29 You should rely only on the information contained in or incorporated by reference in this prospectussupplement and the accompanying prospectus. We have not authorized anyone to provide you with differentor additional information. We are not making an offer of these securities in any state where the offer is notpermitted. You should not assume that the information contained in this prospectus supplement or theaccompanying prospectus is accurate as of any date later than the date on the front of thisprospectussupplement. IMPORTANT NOTICE ABOUT INFORMATION IN THIS PROSPECTUSSUPPLEMENT AND THE ACCOMPANYING PROSPECTUS This document is in two parts. The first part is the prospectus supplement, which describes the specific terms of theNotes being offered. The second part, the base prospectus, gives more general information, some of which may notapply to the Notes being offered. Generally, when we refer to the prospectus, we are referring to both partscombined, and when we refer to the a