The Zurich-listed bank had expected to enjoy a pleasant weekend with clients and business contacts in the city-state ahead of the Formula One Grand Prix motor race – which UBS sponsors. Instead, Oswald Gruebel, the chief executive who had been recruited from retirement to revive the bank’s fortunes, will have to explain to anxious shareholders how UBS intends to respond to the trading loss affair.

UBS is cutting back its investment banking division (IBD) representing between 5 and 10 per cent of the jobs within the Swiss bank's advisory arm, media reports said. These reductions are part of previously announced cuts of 3,500 jobs that had been designed to save around $2 billion. The cuts are not directly related to the recent trading loss, reports said.

UBS shares have fallen by around 12 per cent since last Thursday, when the firm revealed the trading loss caused by unauthorised trading at the investment bank. Shares are down by around 37 per cent since January, only slightly less than the 39 per cent fall in the Bloomberg Europe Banks and Financial Services Index (source: Bloomberg).

Meanwhile, UBS Wealth Management Americas chief executive Robert McCann has sought to reassure the firm’s US-based financial advisors that its wealth business is “stronger than ever.” “We've come too far - with even more potential - to let this setback distract us from our goals and objectives,” McCann reportedly said in a memo sent earlier this week to UBS Wealth Management Americas employees and obtained by On Wall Street.

“Your jobs are demanding as is,” McCann said in the memo. “So I know how much more challenging it becomes when something like this happens. This situation is frustrating and unacceptable.”

Kweku Adoboli, 31, has been arrested and charged with offences connected with the huge losses.

Reuters reported that Gruebel will fight to maintain the investment bank business at UBS, as part of the group's business alongside wealth management. The 67-year-old German, a former bond trader himself, has been delivering "a consistent message" throughout the week, despite UK and Swiss investigations into how Adoboli evaded UBS's compliance department, the news service said, citing unnamed sources.

Some figures in the industry have argued – as reported by WealthBriefing – that the damage to UBS’s wealth management business will be relatively small because clients alarmed over 2008 credit losses and a 2009 tax evasion legal fight with the US in 2009 have already left. No client positions have been affected by the $2.3 billion trading loss, UBS has repeatedly said.