蒙特利尔银行美股招股说明书(2026-09-01版)

The information in this preliminary pricing supplement is not complete and may be changed. This preliminary pricing supplement is not anoffer to sell these securities and is not soliciting an offer to buy these securities in any jurisdiction where the offer or sale is not permitted. Preliminary Pricing Supplement, subject to completion, dated September 1, 2026 US$Senior Medium-Term Notes, Series Jconsisting ofUS$% Fixed/Floating Rate Senior Notes due 2030US$Floating Rate Notes due 2030 This is an offering of US$aggregate principal amount of our% Fixed/Floating Rate Senior Notes due 2030, which we refer to as the “Fixed/Floating Rate Notes”, and US$aggregate principal amount of our Floating Rate Notes due 2030, which we refer to as the “Floating Rate Notes” and, together with the Fixed/Floating Rate Notes, the “Notes”. The Fixed/Floating RateNotes and the Floating Rate Notes will each mature on, 2030. Compounded SOFR (as defined herein) (determined with respect to each quarterly interest period using the SOFR Index (as defined herein)), plus%, payable quarterly on,,and such maturity date. We will pay interest on the Floating Rate Notes at a floating rate equal to Compounded SOFR (determined with respect to each quarterly interest period using the SOFRIndex), plus%, payable quarterly on each,,and, beginning on, 2026. The Notes will be bail-inable notes (as defined in the accompanying prospectus supplement dated March25, 2025) and subject to conversion in whole or in part — by means of a transaction orseries of transactions and in one or more steps — into common shares of Bank of Montreal or any of its affiliates under subsection 39.2(2.3) of theCanada Deposit Insurance Corporation Act(Canada)(the “CDIC Act”) and to variation or extinguishment in consequence, and subject to the application of the laws of the Province of Ontario and the federal laws of Canada applicable therein in respect ofthe operation of the CDIC Act with respect to the Notes. We may, at our option, redeem each tranche of Notes at the applicable times and redemption prices described under the caption “Specific Terms of the Notes — Optional Redemption.” We may also redeem each tranche of Notes in whole at any time upon the occurrence of certain events pertaining to Canadian taxation at 100% of their principal amount, plus accrued and unpaidinterest to, but excluding, the redemption date. See “Specific Terms of the Notes — Tax Redemption.” The Notes will be our senior unsecured obligations and will rank equally in right of payment with all of our existing and future unsubordinated, unsecured indebtedness. The Notes will be issuedonly in registered book-entry form, in minimum denominations of US$2,000 and integral multiples of US$1,000 in excess thereof. Investing in the Notes involves risks, including the risks described in the “Risk Factors” section beginning on page PS-3 of this pricing supplement, those described in the “Risk Factors”section beginning on page S-2 of the accompanying prospectus supplement and those described in management’s discussion and analysis included in our Annual Report on Form 40-F for the yearended October31, 2025, as amended, and subsequent interim reports, which are incorporated by reference in the accompanying prospectus, dated March25, 2025, as supplemented by theaccompanying prospectus supplement, dated March25, 2025, and this pricing supplement. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these Notes or passed upon the adequacy or accuracy of this pricingsupplement or the accompanying prospectus and prospectus supplement. Any representation to the contrary is a criminal offense. The Notes will be our senior unsecured obligations and will not be savings accounts, deposits or other obligations that are insured under the CDIC Act or any other deposit insuranceregime, or by the U.S. Federal Deposit Insurance Corporation or any other governmental agency or instrumentality in Canada, the United States or elsewhere. Table of Contents TABLE OF CONTENTS Pricing Supplement Incorporation of Certain Information by ReferenceRisk FactorsUse of ProceedsSpecific Terms of the NotesSupplemental Tax ConsiderationsEmployee Retirement Income Security ActSupplemental Plan of Distribution (Conflicts of Interest)Validity of the Notes Prospectus Supplement About This Prospectus SupplementRisk FactorsUse of ProceedsDescription of the Notes We May OfferCertain Income Tax ConsequencesSupplemental Plan of Distribution (Conflicts of Interest)Documents Filed as Part of the Registration Statement Prospectus About This ProspectusPresentation of Financial InformationCaution Regarding Forward-Looking StatementsWhere You Can Find More InformationIncorporation of Certain Information by ReferenceRisk FactorsBank of MontrealUse of ProceedsDescription of Common Shares and Preferred SharesDescription of WarrantsDescription of Subscription ReceiptsDescription of D