杰弗里金融集团股份有限公司美国存托凭证招股说明书（2026年6月18日版）

The information in this preliminary pricing supplement is not complete and may be changed without notice. This preliminary pricing supplement is not an offer tosell these securities, nor a solicitation of an offer to buy these securities, in any jurisdiction where the offering is not permitted. PRELIMINARY PRICING SUPPLEMENT(to Prospectus Supplement dated May 11, 2026 and Prospectus datedMay 11, 2026) $Jefferies Jefferies Financial Group Inc.Senior Callable Floating Rate Range Accrual Notes Linked to the 10-Year CMT Rate due June 30, 2031 We have the right to redeem the Notes, in whole or in part, on each Optional Redemption Date. Subject to our redemption right, interest will accrue and be payable monthly, in arrears, from, and including, the Original Issue Date to, but excluding, the stated maturity date (June 30, 2031), at a variable rate per annum equal to (a) the Contingent Rate of 7.50% per annum times(b) the quotient ofNdivided byD, whereN= the number of calendar days during the applicable Interest Payment Period on which the Accrual Provision (defined below) is satisfied andD=the total number of calendar days in such Interest Payment Period. All payments on the Notes, including the repayment of principal, are subject to the credit risk of Jefferies Financial Group SUMMARY OF TERMSIssuer:Title of the Notes:Aggregate Principal Amount:Issue Price: Senior Callable Floating Rate Range Accrual Notes Linked to the 10-Year CMT Rate due June 30, 2031$. We may increase the Aggregate Principal Amount prior to the Original Issue Date but are not required to do so. At variable prices. The Notes will be offered at a price equal to 100% of the Stated Principal Amount per Note until the initial pricing date,which is, 2026. Thereafter, the Notes will be offered from time to time in one or more negotiated transactions at varying prices to bedetermined at the time of each sale, which may be at market prices prevailing, at prices related to such prevailing prices or at negotiatedprices, subject to a maximum price of 100% of the Stated Principal Amount per Note. Stated Principal Amount:Pricing Date:Original Issue Date: $1,000 per NoteJune, 2026 The Payment at Maturity per Note will be the Stated Principal Amount plus accrued and unpaid interest, if any.With respect to any Accrual Determination Date, the yield for United States Treasury securities at “constant maturity” with a designatedmaturity of 10 years, determined as set forth under “The Notes” below. From and including the Original Issue Date to, but excluding, June 30, 2031: For each Interest Payment Period, a variable rate per annumequal to (i) the Contingent Rate times (ii) the quotient ofNdivided byD, whereN= the number of calendar days during the applicableInterest Payment Period on which the Accrual Provision is satisfied andD= the total number of calendar days in such Interest PaymentPeriod. The Interest Rate applicable to each Interest Payment Period will not be greater than 7.50% per annum or less than 0.00% per Interest Rate: Accrual Provision: For each Interest Payment Period, the Accrual Provision shall be deemed to have been satisfied for each calendar day during such InterestPayment Period on which the 10-Year CMT Rate, as determined on the Accrual Determination Date relating to such calendar day, is lessthan or equal to 5.00%. If the 10-Year CMT Rate, as determined on the Accrual Determination Date relating to such calendar day, is greaterthan 5.00%, then the Accrual Provision shall be deemed not to have been satisfied for such calendar day. Accrual Determination Date: With respect to any calendar day during an Interest Payment Period that is also a U.S. Government Securities Business day, such calendarday. With respect to any calendar day during an Interest Payment Period that is not also a U.S. Government Securities Business Day, theimmediately prior U.S. Government Securities Business Day. Notwithstanding the foregoing, for all calendar days in the Exclusion Period, theAccrual Determination Date will be the first U.S. Government Securities Business Day that precedes such Exclusion Period. The Accrual than 5.00% on the first U.S. Government Securities Business Day that precedes such Exclusion Period.For each Interest Payment Period, the period commencing on the fourth business day prior to but excluding the Interest Payment Date forsuch Interest Payment Period. Exclusion Period: Contingent Rate:Interest Payment Period: 7.50% per annumMonthly (from and including the 30th calendar day of each month to, but excluding, the 30th calendar day of the immediately following month, beginning June 30, 2026; provided that any Interest Payment Period which begins or ends in February will begin or end on the last calendarday of such month, as applicable) Interest Payment Dates: The 30th calendar day of each month, beginning July 30, 2026; provided that the Interest Payment Date occurring in each February will bethe last calendar day of s