When Peter Wuffli was ousted as chief executive of UBS in July, some saw it as a harsh response to problems the bank had encountered in the US subprime mortgage market.

After all, its in-house hedge fund, Dillon Read Capital Management, had lost little more than $100m at that stage. But as losses have ballooned his departure has come to look less draconian and it has been followed by a wave of high-ranking casualties across the banking world.