UBS's Gruebel needs more time as clients pull money

While the largest fourth quarter withdrawals were seen at UBS' key Wealth Management and Swiss Bank division, the Americas wealth division also came under pressure, suffering net outflows of 12 billion francs, more than twice analysts' expectations.

Cryan said the positive quarterly figures should encourage clients to stop taking money out of the bank, while Gruebel said he was confident the Swiss government would find "alternative mechanisms" to ensure the U.S. tax deal was honoured.

Pressure from the Italian tax amnesty launched in September and due to run until April added to UBS' woes, triggering net withdrawals of 8.5 billion francs.

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 .

Domestic competitor Credit Suisse, which has fared far better during the financial crisis, is expected to post a 1.3 billion franc quarterly net profit.

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