On Friday, the stock lost 14 per cent, closing at 11 francs.
The decline in value was seen as a reaction to the investigation in the United States into allegations that UBS employees helped clients commit tax fraud and concerns about the fate of the Alpine country’s secret banking laws.
The bank, whose executives admitted employees conducted improper actions, agreed last week to pay a fine of 780 million dollars to US authorities and hand over data on some clients. Reports placed the number at between 250 and 300 names.
Last February, the stock stood at 35 francs.
At the end of 2008, UBS took a bail-out from the Swiss government and central bank, worth about 58 million dollars.
The bank’s executives have come under criticism in Switzerland as the affair has unravelled, as have the US authorities, who have been portrayed as bullies.
The handing over of client details has sparked concern about the future of Swiss banking secrecy laws.
Late Friday, a Swiss high court banned any future transfer of client data until it heard a case brought by eight UBS clients wishing to keep their information secret.
While the US has demanded thousands more names, UBS said it would fight the lawsuit and protect client data. The bank and FINMA, the Swiss regulatory body, said only information on clients accused of fraud were handed over.
The main European economies called for tougher action on tax havens over the weekend at a meeting in Berlin.
German Chancellor Angela Merkel said a list should be drawn up, ahead of the G20 meeting in London on April 2, of “those who refuse to cooperate internationally,” with a view to imposing sanctions against tax havens or regions conducting intransparent business transactions.
Nicolas Hayek, the head of Swatch group, the watch company, made news when he said his company pulled funds out of UBS and the second largest Swiss bank Credit Suisse, over concerns that the financial institutions could become insolvent. (dpa)