Shares in UBS fell on Tuesday to another all-time low as the idea of a task force to try to help resolve the bank's tax problem with the United States gathered pace.
At the close of trading, UBS shares were down 1.5 per cent to SFr9.85 ($8.47), after Monday's close of SFr10.
This means that the stock exchange value of UBS is about SFr30 billion or about as much as its rival Credit Suisse.
In a related development, a Zurich lawyer has laid charges against UBS and the Swiss Financial Supervisory Authority (Finma) of violating Switzerland's banking secrecy legislation.
The US Internal Revenue Service (IRS) wants to gain access to accounts of 52,000 UBS clients in the US suspected of tax evasion.
Its demand last week to acquire information came a day after UBS reached a settlement with the Justice Department on revealing the names of up to 300 US customers and a fine of $780 million.
Swiss Justice Minister Eveline Widmer-Schlumpf travels to Washington on Monday for talks with her new US counterpart, Eric Holder, during which the UBS controversy is high on the agenda.
The Austrian chancellor, Werner Faymann, has defended banking secrecy, arguing on Swiss television on Tuesday that it did not stand in the way of punishing those who committed criminal offences.