The Bank of England knows the risk. Markets director Paul Tucker says the crisis has moved beyond the collapse of mortgage securities, and is now eating into the bedrock of banking capital. "We must try to avoid the vicious circle in which tighter liquidity conditions, lower asset values, impaired capital resources, reduced credit supply, and slower aggregate demand feed back on each other," he says.
New York's Federal Reserve chief Tim Geithner echoed the words, warning of an "adverse self-reinforcing dynamic", banker-speak for a downward spiral. The Fed has broken decades of practice by inviting all US depositary banks to its lending window, bringing dodgy mortgage securities as collateral.