三井住友金融美股招股说明书(2026-01-05版)

The information in this preliminary prospectus supplement and the accompanying prospectus is not complete and may be changed. This preliminaryprospectus supplement and the accompanying prospectus are not an offer to sell these securities and are not soliciting an offer to buy these securities in anyjurisdiction where the offer or sale is not permitted. SUBJECT TO COMPLETION, DATED JANUARY 5, 2026 PRELIMINARY PROSPECTUS SUPPLEMENT(To prospectus dated January11, 2024) Sumitomo Mitsui Financial Group, Inc.(incorporated under the laws of Japan with limited liability) U.S.$Senior Fixed Rate NotesSenior Floating Rate NotesSenior Callable Fixed-to-Floating Rate NotesSenior Callable Floating Rate Notes We expect to issue one or more series of the above-listed senior notes in aggregate principal amounts to be determined.The senior fixed rate notes due, or the non-callable fixed rate notes, will bear interest commencing, 2026 at the rate of%per annum, payable semiannually in arrears onandof each year, beginning on, 2026.The senior floating rate notes due, or the non-callable floating rate notes, will bear interest commencing, 2026 at a floating rate per annum, equal to Compounded Daily SOFR (determined asprovided under “Description of the Notes”), plus% payable quarterly in arrears on,,andof each year, beginning on, 2026, subject to adjustments.The senior callable fixed-to-floating rate notes due, or the callable fixed-to-floating rate notes, will bear interest (i)from and including, 2026 to but excluding the date that is one year prior tothe maturity date at a fixed rate of%per annum, payable semiannually in arrears onandof each year, beginning on, 2026, and (ii)from and including the date that is one yearprior to the maturity date to but excluding the maturity date, at a floating rateper annum, equal to Compounded Daily SOFR (determined as provided under “Description of the Notes—Calculation of Floating InterestRates”) plus%, reset quarterly, payable quarterly in arrears on,,andof each year, beginning on, 20, subject to adjustments.The senior callable floating rate notes due, or the callable floating rate notes, and together with the non-callable fixed rate notes, the non-callable floating rate notes and the callable fixed-to-floating ratenotes, the notes, will bear interest commencing, 2026 at a floating rateper annum, equal to Compounded Daily SOFR (determined as provided under “Description of the Notes—Calculation of FloatingInterest Rates”) plus%, reset quarterly, payable quarterly in arrears on,,andof each year, beginning on, 2026, subject to adjustments. The non-callablefloating rate notes and the callable floating rate notes are together referred to as the floating rate notes.Each series of the callable fixed-to-floating rate notes and the callable floating rate notes may be redeemed on the date that is one year prior to the maturity date of such series of notes, as described under“Description of the Notes—Optional Redemption.” In addition, each series of the notes may be redeemed at any time prior to maturity in the circumstances described under “Description of the Notes—Redemption forTaxation Reasons.” The notes will not be subject to any sinking fund. The notes will be issued only in registered form in minimum denominations of U.S.$200,000 and integral multiples of U.S.$1,000 in excess thereof. We have made an application to the Luxembourg Stock Exchange to list the notes on the official list of the Luxembourg Stock Exchange and for such notes to be admitted to trading on the Luxembourg StockExchange’s Euro MTF Market. The Luxembourg Stock Exchange’s Euro MTF Market is not a regulated market for the purposes of Directive 2014/65/EU. This prospectus supplement with the accompanyingprospectus constitutes a prospectus for purposes of Part IV of the Luxembourg law on prospectuses for securities dated July16, 2019. This prospectus supplement and the accompanying prospectus do not constitute a prospectus for the purposes of Regulation (EU) 2017/1129 (as amended, the “Prospectus Regulation”) as it forms part ofdomestic law by virtue of the European Union (Withdrawal) Act 2018 (the “EUWA”) (the “U.K. Prospectus Regulation”). Investing in the notes involves risks. You should carefully consider the risk factors set forth in “Item 3. Key Information—Risk Factors” of our most recent annual report onForm 20-F filed with the U.S. Securities and Exchange Commission, or the SEC, and in the “Risk Factors” section beginning on page S-13 of this prospectus supplement beforemaking any decision to invest in the notes. Neither the SEC nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus supplementor the related prospectus. Any representation to the contrary is a criminal offense. The notes of each series will be represented by one or more global certificates deposited with a custodian for, and registered in the name of a nominee