Jefferies Financial Group Inc美股招股说明书(2026-08-13版)

The information in this preliminary pricing supplement is not complete and may be changed without notice. This preliminarypricing supplement is not an offer to sell these securities, nor a solicitation of an offer to buy these securities, in anyjurisdiction where the offering is not 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 August 13, 2026 $Jefferies Jefferies Financial Group Inc.Senior Autocallable Contingent Coupon Barrier Notes due September 3, 2031 Linked to the Worst-Performing of the Dow Jones Industrial Average®, the Russell 2000®Index and the S&P 500®Index The Senior Autocallable Contingent Coupon Barrier Notes due September 3, 2031 Linked to the Worst-Performing of the Dow Jones Industrial Average®, the Russell 2000®Index and theS&P 500®Index (the “Notes”) are senior unsecured obligations of Jefferies Financial Group Inc. The Notes have the terms described in the accompanying product supplement, prospectussupplement and prospectus, as supplemented or modified by this pricing supplement. The Notes are issued as part of our Series A Global Medium-Term Notes program.All payments are subject to our credit risk. If we default on our obligations, you could lose some or a significant portion of your investment. These Notes are not secured obligations and you will not have any security interest in, or otherwise have any access to, any Underlying or the securities represented by any Underlying.SUMMARY OF TERMS Senior Autocallable Contingent Coupon Barrier Notes due September 3, 2031 Linked to the Worst-Performing of the Dow Jones Industrial Average®, theRussell 2000®Index and the S&P 500®Index$. 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:Coupon Observation Dates: September 2, 2026 (3 Business Days after the Pricing Date)Quarterly, beginning on November 30, 2026, as set forth on page PS-2. The Coupon Observation Dates are subject to postponement as described in the accompanying product supplement. Coupon Payment Dates: Call Observation Dates: Quarterly, beginning on August 28, 2028, as set forth on page PS-2. The Call Observation Dates are subject to postponement as described in theaccompanying product supplement.As set forth on page PS-2. The Call Payment Dates may be postponed if the related Call Observation Date is postponed as described in the Call Payment Dates: Valuation Date:Maturity Date:Underlying: August 28, 2031, subject to postponement as described in the accompanying product supplement.September 3, 2031, which may be postponed if the Valuation Date is postponed as described in the accompanying product supplement. The worst-performing of the Dow Jones Industrial Average®(the “INDU”), the Russell 2000®Index (the “RTY”) and the S&P 500®Index (the “SPX”).Please see “The Underlyings” below.Worst-Performing Underlying:The Underlying with the lowest Observation Value or Final Value, as applicable, as compared to its Initial Value. Coupon Feature: Contingent Coupon Payments. The Notes will pay a Contingent Coupon Payment of $21.50 on the applicable Coupon Payment Date if the Observation Value of the Worst-Performing Underlying on the applicable quarterly Coupon Observation Date is greater than or equal to its Coupon Barrier.Autocallable Notes. The Notes will be automatically called if the Observation Value of the Worst-Performing Underlying on any Call Observation Date(beginning approximately two years after the Pricing Date) is equal to or greater than its Call Value. If your Notes are called, you will receive the CallPayment on the applicable Call Payment Date, and no further amounts will be payable on the Notes.The Stated Principal Amount plus any Contingent Coupon Payment that may otherwise be due on the applicable Call Payment Date. Call Feature: Call Payment:Payment at Maturity: If the Final Value of the Worst-Performing Underlying is greater than or equal to its Threshold Value, you will receive for each Note that you hold a Payment at Maturity that is equal to the Stated Principal AmountIf the Final Value of the Worst-Performing Underlying is less than its Threshold Value, you will receive for each Note that you hold a Payment at Maturity that is less than the Stated Principal Amount of each Note that will equal: In this scenario the Payment at Maturity will be less than the Stated Principal Amount and you could lose some or all of your investment. The Payment at Maturity will also include the final Contingent Coupon Payment if the Observation Value of the Worst-Performing Underlying on the finalCoupon Observation Date is greater than or equal to its Coupon Barrier.With respect to each Underlying, the Index Closing Value of the Underlyin