The landlord is complying with a city ordinance that mandates security deposits must earn interest that belongs to you.
A security deposit and interest due thereon shall continue to be the property of the tenant making such deposit, shall not be commingled with the assets of the landlord, and shall not be subject to the claims of any creditor of the landlord or of the landlord’s successors in interest, including a foreclosing mortgagee or trustee in bankruptcy.