"We must also see that we still earn decent money. That will certainly be the biggest challenge in 2017," Blessing, who joined UBS in September, said at a banking conference organised by Swiss newspaper Finanz und Wirtschaft.

One factor making things tougher for banks in Switzerland is the Swiss central bank's negative interest rate policy. Blessing said UBS has no plans to pass on negative rates to retail clients.

(Reporting by Joshua Franklin and Angelika Gruber)