Last week, Massachusetts’ top securities regulator filed civil charges against UBS for allegedly selling investments the Swiss bank knew were not safe. The case is being closely watched by the banking sector, not least because it contained some of the first official complaints to stem from regulatory probes into the collapse of the auction-rate securities market in February.

Nearly all of the leading investment banks are the subject of various investigations into the failure of this $330bn segment of the bond market, one of the biggest casualties of the credit crunch.