Attention has focused on the danger presented by the failure of Lehman Brothers. But as the UK discovered during the Northern Rock crisis, the failure of a large traditional bank, such as Washington Mutual, could have systemic consequences if it undermines confidence in other weak lenders.

WaMu, the largest savings and loans bank in the US, lost more than a third of its market value in the past week as investors feared it lacked liquidity and capital to survive the credit crisis.