UBS back to profit in fourth quarter

"The return to positive figures in the fourth quarter is very pleasing and (should) sooth investors' nerves, which have been rocked by recent developments," said Wegelin analysts.

Gruebel and Villiger said they were confident the Swiss government would find "alternative mechanisms" to ensure the U.S. tax deal was honoured.

McCann has yet to unveil his strategy, while many analysts are betting Gruebel may end up selling the division.

Pressure from the Italian tax amnesty launched in September and due to run until April added to UBS' woes on the wealth management front, triggering net withdrawals of 8.5 billion francs from its large Italian client base.

UBS' direct rival Credit Suisse , which has fared far better during the financial crisis, is expected to post a 1.3 billion franc net profit.

UBS is facing a more competitive environment in the United States as the crisis led to the emergence of brokerage giants Morgan Stanley Smith Barney , Bank of America-Merrill Lynch and Wells Fargo .

(Additional reporting by Jason Rhodes and Katie Reid; editing by John Stonestreet)