A long-awaited turnaround in UBS's wealth management business helped Switzerland's biggest bank deliver its second-best start to a year since the financial crisis.

But the bank still struck a cautious tone for the year ahead. 

Rising interest rates, a booming stock market and better investor sentiment boosted the group's US business.

Improving Asian markets also meant clients were more willing to take risks after a slowdown in late 2015 blunted trading appetite. 

The world's largest wealth manager said that net profit for the first three months of 2017 jumped 79% to 1.3 billion Swiss francs ($1.3 billion), beating the highest forecast in a Reuters poll. 

UBS's strength contrasts with that of Swiss neighbour Credit Suisse which is recovering from back-to-back annual losses and is asking shareholders for billions of Swiss francs in fresh capital. 

UBS warned, however, that while the global economy is likely to continue recovering, geopolitical tensions and 'divisive politics' could hurt confidence and business. 

One such uncertainty is Britain's departure from the European Union, something UBS said could lead to "potentially significant changes to our operations in the UK and our legal structure", according to its chief executive Sergio Ermotti.

Net new money, an important indicator for future revenue in private banking, came in at 18.6 billion francs at UBS Wealth Management - a 7.6% rise and far ahead of the bank's 3-5% growth target. 

UBS had said it hoped optimism surrounding new US President Donald Trump's proposed policies would boost its core wealth management business. 

That optimism - communicated just seven days after Trump took office in January - translated into a 10% rise in transaction-based income for Wealth Management Americas, even as the unit's gross margin dipped compared to the previous quarter.

At its wealth management unit outside North America - traditionally more profitable but facing greater pressure from negative and low interest rates - a rebound in trading generated record revenues and profit before tax in Asia Pacific.

Gross margins in wealth management rose quarter-on-quarter for the first time in two years, a metric analysts had been looking to as an important sign of an anticipated rebound.