Jefferies Financial Group Inc美股招股说明书(2026-06-24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 June 24, 2026 $Jefferies Jefferies Financial Group Inc.Senior Autocallable Contingent Coupon Barrier Notes due July 8, 2032 Linked to the Worst-Performing of the Nasdaq-100 Index®, the Russell 2000®Index and the VanEck® Semiconductor ETFThe Senior Autocallable Contingent Coupon Barrier Notes due July 8, 2032 Linked to the Worst-Performing of the Nasdaq-100 Index®, the Russell 2000®Index and the VanEck ®Semiconductor ETF (the “Notes”) are senior unsecured obligations of Jefferies Financial Group Inc. The Notes have the terms described in the accompanying product supplement,prospectus supplement and prospectus, as supplemented or modified by this pricing supplement. The Notes are issued as part of our Series A Global Medium-Term Notes program.All payments are subject to our credit risk. If we default on our obligations, you could lose some or a significant portion of your investment. These Notes are not securedobligations and you will not have any security interest in, or otherwise have any access to, any Underlying or the securities represented by any Underlying.SUMMARY OF TERMS AggregatePrincipal Amount:$. We may increase the Aggregate Principal Amount prior to the Original Issue Date but are not required to do so. Monthly, beginning on August 3, 2026, as set forth on page PS-2. The Coupon Observation Dates are subject to postponement as described in the accompanying Coupon PaymentDates:As set forth on page PS-2. The Coupon Payment Dates may be postponed if the related Coupon Observation Date is postponed as described in the accompanyingproduct supplement. Call ObservationMonthly, beginning on January 4, 2027, as set forth on page PS-2. The Call Observation Dates are subject to postponement as described in the accompanying productsupplement.Call PaymentAs 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 accompanying product July 2, 2032, subject to postponement as described in the accompanying product supplement. July 8, 2032, which may be postponed if the Valuation Date is postponed as described in the accompanying product supplement. Valuation Date:Maturity Date: The worst-performing of the Nasdaq-100 Index®(the “NDX”), the Russell 2000®Index (the “RTY”) and the VanEck®Semiconductor ETF (the “SMH”). Please see “The Worst-PerformingUnderlying:The Underlying with the lowest Observation Value or Final Value, as applicable, as compared to its Initial Value. Autocallable Notes. The Notes will be automatically called if the Observation Value of the Worst-Performing Underlying on any Call Observation Date (beginningapproximately six months after the Pricing Date) is equal to or greater than its Call Value. If your Notes are called, you will receive the Call Payment on the applicableCall 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.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: The Payment at Maturity will also include the final Contingent Coupon Payment if the Observation Value of the Worst-Performing Underlying on the final CouponObservation Date is greater than or equal to its Coupon Barrier.With respect to theSMH, the ETF Closing Price of the Underlying on the Pricing Date. Initially 1.0 with respect to the SMH, subject to adjustment for certain events affecting the Underlying. See “—Antidilution Adjustments for Exchange Traded Funds” inthe accompanying product supplement.U.S. dollars Approximately $984.00 per Note, or within $30.00 of that estimate. Please see “The Notes” below. Conflict ofInterest:Jefferies LLC, the broker-dealer subsidiary of Jefferies Financial Group Inc., is a member of FINRA and will participate in the distribution of the notes being offeredhereby. Accordingly, the offering is subject to the provisions of FINRA Rule 5121 relating to conflicts of interest and will be conducted in accordance with therequirements of Rule 5121. See “Conflict of Interest.”The Notes will be our se