Jefferies Financial Group Inc美股招股说明书(2026-05-18版)

The information in this preliminary pricing supplement is not complete and may be changed without notice. This preliminary pricingsupplement is not an offer to sell these securities, nor a solicitation of an offer to buy these securities, in any jurisdiction where the offering isnot permitted. PRELIMINARY PRICING SUPPLEMENT(to Product Supplement no. 5, dated May 11, 2026,Prospectus Supplement dated May 11, 2026and Prospectus dated May 11, 2026) SUBJECT TO COMPLETION, DATED May 15, 2026 $Jefferies Jefferies Financial Group Inc.Senior Autocallable Buffered Leveraged Notes due May 28, 2031Linked to the Worst-Performing of the Class A Common Stock of Alphabet Inc., the Common Stock of Microsoft Corporation and the Common Stock ofTesla, Inc. The Senior Autocallable Buffered Leveraged Notes due May 28, 2031 Linked to the Worst-Performing of the Class A Common Stock of Alphabet Inc., the Common Stock of MicrosoftCorporation and the Common Stock of Tesla, Inc. (the “Notes”) are senior unsecured obligations of Jefferies Financial Group Inc. The Notes will pay no interest and have the termsdescribed in the accompanying product supplement, prospectus supplement and prospectus, as supplemented or modified by this pricing supplement. The Notes will be automaticallycalled if the Observation Value of each Underlying on the Call Observation Date (August 24, 2026) is equal to or greater than its Call Value. If your Notes are called, you will receive the CallPayment on the Call Payment Date, and no further amounts will be payable on the Notes. If your Notes are not called, at maturity, if the Worst-Performing Underlying hasappreciatedinvalue, investors will receive the Stated Principal Amount of their investment plus 200.00% of the upside performance of the Worst-Performing Underlying. If the Worst-Performing Underlyinghasdepreciatedin value, but the Worst-Performing Underlying has not declined below its Threshold Value, investors will receive the Stated Principal Amount. However, if the Worst-Performing Underlying has declined below its Threshold Value, investors will lose approximately 1.66667% of the Stated Principal Amount for every 1% decline (as compared to the InitialValue of the Worst-Performing Underlying) in the Final Value of the Worst-Performing Underlying below its Threshold Value. Investors may lose up to 100% of the Stated Principal Amountof the Notes. The Notes are issued as part of our Series A Global Medium-Term Notes program.All payments are subject to our credit risk. If we default on our obligations, you could lose some or a significant portion of your investment. These Notes are not secured obligations and you will not have any security interest in, or otherwise have any access to, any Underlying.SUMMARY OF TERMS Senior Autocallable Buffered Leveraged Notes due May 28, 2031 Linked to the Worst-Performing of the Class A Common Stock of Alphabet Inc., theCommon Stock of Microsoft Corporation and the Common Stock of Tesla, Inc.$. We may increase the Aggregate Principal Amount prior to the Original Issue Date but are not required to do so. Title of the Notes: Aggregate Principal Amount:Issue Price:Stated Principal Amount:Pricing Date:Original Issue Date:Call Observation Date:Call Payment Date: May 28, 2026 (3 Business Days after the Pricing Date)August 24, 2026. The Call Observation Date is subject to postponement as described in the accompanying product supplement. August 27, 2026. The Call Payment Date may be postponed if the related Call Observation Date is postponed as described in the accompanyingproduct supplement.May 22, 2031, subject to postponement as described in the accompanying product supplement. Valuation Date:Maturity Date:Underlying: May 28, 2031, which may be postponed if the Valuation Date is postponed as described in the accompanying product supplement. The worst-performing of the Class A common stock of Alphabet Inc. (Nasdaq symbol: “GOOGL”), the common stock of Microsoft Corporation (Nasdaqsymbol: “MSFT”) and the common stock of Tesla, Inc. (Nasdaq symbol: “TSLA”) (each an “Underlying Company” and collectively, the “UnderlyingCompanies”). Please see “The Underlyings” below.The Underlying with the lowest Underlying Return. Worst-Performing Underlying:Autocall Feature: The Notes will be automatically called if the Observation Value of each Underlying on the Call Observation Date is equal to or greater than its CallValue. If your Notes are called, you will receive the Call Payment on the Call Payment Date, and no further amounts will be payable on the Notes.$1,115.00 per Note.If the Final Value of the Worst-Performing Underlying is greater than its Initial Value, you will receive for each Note that you hold a Payment at Call Payment:Payment at Maturity: Maturity equal to: Stated Principal Amount × (1+ Participation Rate × Underlying Return of the Worst-Performing Underlying).If the Final Value of the Worst-Performing Underlying is less than or equal to its Initial Value b