Deutsche Bank grappling with a series of legal problems on both sides of the Atlantic, warned that restructuring costs would result in a substantial hit to the bank's fourth-quarter earnings and could tip it into a loss for the last three months of the year.

The bank said on Thursday that the fourth quarter would be affected by one-time charges linked to its restructuring plans and its integration of retailer Postbank, as well as charges from its transaction banking activities in the Netherlands.