UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington D.C. 20549

FORM FOR SUBMISSION OF ELECTRONIC EXHIBITS FOR

ASSET-BACKED SECURITIES

Commission File Number of issuing entity: 333-280224-14

Central Index Key Number of Issuing entity: 0002128774

BMO 2026-5C15 MORTGAGE TRUST
(Exact name of issuing entity as specified in its charter)

Commission File Number of depositor: 333-280224

Central Index Key Number of depositor: 0001861132

BMO Commercial Mortgage Securities LLC
(Exact name of depositor as specified in its charter)

Central Index Key Number of sponsor (if applicable): 0000927971

Bank of Montreal
(Exact name of Sponsor as specified in its charter)

Central Index Key Number of sponsor (if applicable): 0001685185

UBS AG New York Branch
(Exact name of Sponsor as specified in its charter)

Central Index Key Number of sponsor (if applicable): 0002058685

3650 Capital SCF LOE I(A), LLC
(Exact name of Sponsor as specified in its charter)

Central Index Key Number of sponsor (if applicable): 0000109380

Zions Bancorporation, N.A.
(Exact name of Sponsor as specified in its charter)

Central Index Key Number of sponsor (if applicable): 0000740906

Wells Fargo Bank, National Association
(Exact name of Sponsor as specified in its charter)

Central Index Key Number of sponsor (if applicable): 0001722518

BSPRT CMBS Finance, LLC
(Exact name of Sponsor as specified in its charter)

Central Index Key Number of sponsor (if applicable): 0001541502

Goldman Sachs Mortgage Company
(Exact name of Sponsor as specified in its charter)

Central Index Key Number of sponsor (if applicable): 0001755531

Societe Generale Financial Corporation
(Exact name of Sponsor as specified in its charter)

Central Index Key Number of sponsor (if applicable): 0001541468

Ladder Capital Finance LLC
(Exact name of Sponsor as specified in its charter)

Paul Vanderslice (212) 885-4000
(Name and telephone number, including area code, of the person to contact in connection with this filing)

INFORMATION TO BE INCLUDED IN THIS FORM

Item 1. File an Asset Data File in accordance with Exhibit 601(b)(102) (17 CFR 229.601(b)(102)).

Item 2. File an Asset Related Document in accordance with Exhibit 601(b)(103) (17 CFR 229.601(b)(103)).

SIGNATURES

The depositor has duly caused this Form to be signed on its behalf by the undersigned hereunto duly authorized.

BMO Commercial Mortgage Securities LLC
(Depositor)

/s/ Paul Vanderslice
Paul Vanderslice, Chief Executive Officer

Dated : September 1, 2026

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