Out of the Gate: UBS sinks on board reshuffle

Separately, the U.S. Justice Department said it is seeking information from the bank about U.S. clients who allegedly used the bank to avoid paying federal income taxes.

American Depositary Receipts of UBS fell 97 cents, or 4.7 percent, to $19.69 after touching a five-year low of $19.62 in morning trading. ADRs, or American Depositary Receipts, are securities designed to allow U.S. investors to trade shares of companies based overseas.

UBS said four of the bank's 12 board members will step down in conjunction with a shareholders meeting Oct. 2, during which the bank is likely to inform investors about the results of efforts to ease the fallout from its subprime investments.

Shares of the No. 1 Swiss bank have withered in the wake of the U.S. subprime mortgage crisis. The bank has written down $37.4 billion over the past 10 months. The stock has declined 53 percent since the start of the year.