Commerzbank said Wednesday (August 5) it expects a loss for the year.
The German bank blamed a writedown on loans to the scandal-hit Wirecard and fallout from the global health crisis.
The bank's outlook comes as net profit fell by just over a fifth in the second quarter - at $260 million.
Commerzbank said provisions for credit losses had risen to around $557 million.
About $207 million of that is related to Wirecard.
The German payments firm collapsed last month after an accounting scandal.
Despite that, shares rose by 4% in early trade as profits were above the consensus forecast.
Commerzbank is trying to strengthen its position after its CEO Martin Zielke quit last month.
The search is still underway for a new boss.
Staff cuts, branch closures and the streamlining of international operations are also under discussion.
German insurer Allianz also posted its second quarter struggles on Wednesday.
Profit fell 29% in Q2 from a year earlier.
Allianz also did not update its full-year guidance.