SCHEDULE 13G 0002073926 XXXXXXXX LIVE Class A Ordinary Shares, par value $0.0001 09/30/2025 0002073928 M3-Brigade Acquisition VI Corp. G63221108 1700 BROADWAY, 19TH FLOOR NEW YORK NY 10019 Rule 13d-1(d) M3-Brigade Sponsor VI LLC DE 8625000.00 0.00 8625000.00 0.00 8625000.00 N 20.0 OO M3-Brigade Acquisition Partners VI Corp. DE 8625000.00 0.00 8625000.00 0.00 8625000.00 N 20.0 CO Mohsin Y. Meghji X1 8625000.00 0.00 8625000.00 0.00 8625000.00 N 20.0 IN M3-Brigade Acquisition VI Corp. 1700 Broadway, 19th Floor, New York, NY 10019 This statement is being filed on behalf of each of the following persons (each, a "Reporting Person" and, collectively, the "Reporting Persons"): 1. M3-Brigade Sponsor VI LLC 2. M3-Brigade Acquisition Partners VI Corp. 3. Mohsin Y. Meghji 1700 Broadway, 19th Floor New York, NY 10019 See row 4 of the cover page of each Reporting Person. Y M3-Brigade Sponsor VI LLC (the "Sponsor") directly owns 8,625,000 Class B ordinary shares, par value $0.0001 per share ("Class B Ordinary Shares"), of M3-Brigade Acquisition VI Corp. (the "Issuer"), which are convertible into the Issuer's Class A ordinary shares, par value $0.0001 per share ("Class A Ordinary Shares"). Such shares may be deemed to be beneficially owned by M3-Brigade Acquisition Partners VI Corp. ("MBAP"), which is the general partner of the Sponsor, and Mohsin Y. Meghji, who is the sole director of MBAP. As a result of these relationships, each of the Sponsor, MBAP and Mr. Meghji may be deemed to have or share beneficial ownership of the securities held directly by the Sponsor. Each of the Sponsor, MBAP and Mr. Meghji disclaims beneficial ownership of such securities except to the extent of their direct ownership. In addition to the securities reported on the cover pages hereto, the Sponsor also directly owns 4,333,333 private placement warrants to purchase 4,333,333 Class A Ordinary Shares. The warrants become exercisable beginning 30 days after the completion of the Issuer's initial business combination and expire five years after the completion of the Issuer's initial business combination or earlier upon redemption or liquidation. Percentage ownership is based on 34,500,000 Class A Ordinary Shares outstanding as of October 8, 2025, as reported by the Issuer in its quarterly report on Form 10-Q for the period ended June 30, 2025, and 8,625,000 Class B Ordinary Shares directly owned by the Sponsor, and assumes conversion of such Class B Ordinary Shares into Class A Ordinary Shares. See row 9 of the cover page of each Reporting Person. See row 11 of the cover page of each Reporting Person. See row 5 of the cover page of each Reporting Person. See row 6 of the cover page of each Reporting Person. See row 7 of the cover page of each Reporting Person. See row 8 of the cover page of each Reporting Person. Y Y Y Y Y Y Exhibit 99.1: Joint Filing Agreement, dated as of November 12, 2025, by and among M3-Brigade Sponsor VI LLC, M3-Brigade Acquisition Partners VI Corp. and Mohsin Y. Meghji. M3-Brigade Sponsor VI LLC /s/ Mohsin Y. Meghji 11/12/2025 M3-Brigade Acquisition Partners VI Corp. /s/ Mohsin Y. Meghji 11/12/2025 Mohsin Y. Meghji /s/ Mohsin Y. Meghji 11/12/2025