Form 6-K BANK OF MONTREAL /CAN/ For: Sep 15

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

Report of Foreign Private Issuer

Pursuant to Rule 13a-16 or 15d-16

of the Securities Exchange Act of 1934

For the month of: September, 2026

Commission File Number: 001-13354

BANK OF MONTREAL

(Name of Registrant)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F:

Form 20-F ☐ Form 40-F ☒

INCORPORATION BY REFERENCE

The information contained in this Form 6-K and any exhibits hereto shall be deemed filed with the Securities and Exchange Commission (“SEC”) solely for purposes of incorporation by reference into and as part of the following registration statement of the registrant on file with and declared effective by the SEC:

EXHIBIT INDEX

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.