Ermotti issued his plea to UBS employees in a memo, reported Reuters. The Swiss firm is seeking to battle back from suffering a $2.3 million loss caused by unauthorised trading. The development has raised fresh questions about whether UBS’s investment banking operations sit comfortably with its wealth management business. The bank, along with Swiss and UK national regulators, is investigating the affair.

"The unauthorised trading incident has deeply frustrated all of us. It has dealt us a severe setback to our efforts to regain trust and make UBS the leading bank for our clients," the memo reportedly said. "I have no magic recipe to inspire you to redouble your efforts. I can only appeal to your professionalism, your loyalty and your determination to succeed," Ermotti said.

The comments echo remarks made to journalists by UBS chairman Kaspar Villiger and Ermotti in a conference call at the weekend. UBS said it has already embarked on moves to reduce risk exposures, in part due to the more restrictive capital limits required of Swiss banks. The bank said it will issue more details on this area in November.

Ermotti took up the interim CEO role after his predecessor, Oswald Grübel, announced he would resign with immediate effect.

In the memo, Ermotti said he intended to exercise his authority to support and conclude internal and external investigations looking into the trading loss, and to review the effectiveness and efficiency of the bank's operating model.

In the wake of the 2008 financial market losses that UBS sustained, the bank has already moved to make its investment banking, wealth management and asset management arms more autonomous, short of creating entirely separate companies, as some observers at the time suggested.