Jefferies Financial Group Inc 美股招股说明书（2026年6月16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. SUBJECT TO COMPLETION, DATED June 15, 2026 PRELIMINARY PRICING SUPPLEMENT(to Prospectus Supplement dated May 11, 2026 and Prospectus datedMay 11, 2026) $Jefferies Jefferies Financial Group Inc.Senior Fixed Rate 10-Year Callable Notes due June 30, 2036 We have the right to redeem the Notes, in whole or in part, on each Optional Redemption Date. Subject to our redemption right, the amount of interest payable on the Notes will be 6.00%from and including the Original Issue Date to, but excluding, the stated maturity date (June 30, 2036). All payments on the Notes, including the repayment of principal, are subject to the SUMMARY OF TERMS Issuer: Jefferies Financial Group Inc. June 30, 2026 6.00%, from and including the Original Issue Date to, but excluding, June 30, 2036.Semi-annual (from and including the 30th calendar day of each June and December to, but excluding, the 30th calendar day of the monthoccurring six months following such month, beginning June 30, 2026) Interest Payment Period: Interest Payment Dates:Day-Count Convention:Redemption: We will have the right to redeem the Notes, in whole or in part on each Optional Redemption Date and pay to you 100% of the statedprincipal amount per Note plus accrued and unpaid interest to, but excluding, such Optional Redemption Date. If we elect to redeem theNotes, we will give you notice at least 5 Business Days before the date of such redemption. The 30th calendar day of each June and December, beginning June 30, 2028 and ending December 30, 2035. Optional Redemption Dates: Specified Currency:CUSIP/ISIN:Book-entry or Certificated Note:Business Day: 47233WMX4 / US47233WMX47 New York. If any Interest Payment Date, any Optional Redemption Date or the Maturity Date occurs on a day that is not a Business Day, anypayment owed on such date will be postponed as described in “The Notes” below. Jefferies LLC, a wholly-owned subsidiary of Jefferies Financial Group Inc. See “Supplemental Plan of Distribution.” Agent: General corporate purposes Jefferies LLC, the broker-dealer subsidiary of Jefferies Financial Group Inc., is a member of FINRA and will participate in the distribution ofthe notes being offered hereby. Accordingly, the offering is subject to the provisions of FINRA Rule 5121 relating to conflicts of interest andwill be conducted in accordance with the requirements of Rule 5121. See “Conflict of Interest.” (1) The Agent may purchase the Notes for sale to certain fee-based advisory accounts and may forgo some or all of their underwriting discounts and commissions. The price for investorspurchasing the Notes in these accounts will be reduced by an amount that will be up to such forgone underwriting discounts and commissions. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this pricingsupplement or the accompanying prospectus or either prospectus supplement is truthful or complete. Any representation to the contrary is a criminal offense. JefferiesPricing supplement dated, 2026.You should read this document together with the related prospectus and prospectus supplement,each of which can be accessed via the hyperlinks below, before you decide to invest.Prospectus Supplement dated May 11, 2026 and Prospectus dated May 11, 2026 You should rely only on the information contained in or incorporated by reference in this pricing supplement and theaccompanying prospectus and prospectus supplements. We have not authorized anyone to provide you with differentinformation. We are not making an offer of these securities in any state where the offer is not permitted. You should not Table of Contents SPECIAL NOTE ON FORWARD-LOOKING STATEMENTS This pricing supplement and the accompanying prospectus and prospectus supplement contain or incorporate by reference “forward-looking statements” within the meaning of the safe harbor provisions of Section 27A of the Securities Act of 1933 (the “Securities Act”)and Section 21E of the Securities Exchange Act of 1934. These forward-looking statements are not statements of historical fact andrepresent only our belief as of the date such statements are made. There are a variety of factors, many of which are beyond our control,which affect our operations, performance, business strategy and results and could cause actual reported results and performance todiffer materially from the performance and expectations expressed in these forward-looking statements. These factors include, but arenot limited to, financial market volatility, actions and initiatives by current and future competitors, general economic conditions, controls Tab