It's not been a good week for UBS.

The Swiss bank's share price has fallen sharply after it warned it could see more mortgage losses.

It's been revealed that its vice-chairman, former US Republican senator Phil Gramm, was simultaneously being paid to lobby Congress about mortgage law and chairing John McCain's election campaign. (This is more of a problem for McCain, whose campaign team now seems to have included a surprisingly large number of lobbyists.)

And it's had to warn its private banking team to stay away from the US or risk being arrested for tax evasion.

And it's still only Wednesday...