Swiss banking giant UBS on Tuesday posted a 79-percent higher net profit for 2015, beating analyst expectations, with tax benefits offsetting a difficult fourth quarter hit by market turmoil.

Last year, Switzerland's largest bank raked in a net profit of 6.2 billion Swiss francs ($6.1 billion, 5.5 billion euros), it said in its earning statement.

"Despite a very challenging environment, we had an excellent year," UBS chief Sergio Ermotti said in the statement.

Investors were not convinced. After UBS released its results, it saw its share price shrink more than 7.0 percent to 15.50 francs a piece as the Swiss stock exchange's main SMI index dipped 1.5 percent.

The bank acknowledged that its "fourth quarter was characterised by very low levels of client activity and pronounced risk aversion."

But thanks to a hefty net tax benefit, UBS still easily outperformed expectations.

For the October to December quarter, the bank posted a net profit of 949 million Swiss francs, up from 858 million a year earlier.

Analysts polled by the AWP financial news agency had expected UBS to post a net profit of 626 million Swiss francs for the quarter.

UBS said its fourth quarter result included a net tax benefit of 715 million francs, mainly linked to an "upward revaluation of deferred tax assets", counterbalanced by 365 million francs in provisions for litigation and regulatory matters.

The quarter also included a charge of 257 million linked to a debt buyback programme.

UBS's vital wealth management division meanwhile saw its adjusted profit before tax swell 13 percent in 2015 to 2.8 billion francs -- its best result since 2008.

And it pulled in 22.8 billion in new money under its management during the year.

But during the final quarter of the year, the division saw its operating profit plunge 47 percent to 344 billion francs "amid very low levels of client activity," UBS said.

And during the quarter, net new money outflows ticked in at 3.4 billion francs as clients, especially in emerging markets and Europe, liquidated their positions to reduce debt, more than offsetting continued inflows from the Asia Pacific region and Switzerland.

The US wealth management division, which is counted separately, had an even rougher quarter, seeing its operating profit plunge 94 percent to just $13 billion amid "substantial charges for litigation, regulatory and similar matters".

The investment bank division meanwhile posted a 1.8-billion-franc profit for the year, but was slammed in the fourth quarter by the global market slowdown, seeing its operating profit slump 63 percent to 80 million Swiss francs.

Looking forward, the bank acknowledged that the macroeconomic challenges it has been facing were "unlikely to be resolved in the foreseeable future."

"Negative market performance and substantial market volatility since the start of 2016, low interest rates, and the relative strength of the Swiss franc, particularly against the euro, continue to present headwinds," UBS said.

The bank said it aimed to pay a 2015 dividend to shareholders of 0.60 francs per ordinary share and a special dividend of 0.25 francs.