A turbulent week of trading ended with US stocks finishing lower for the third time in five days.

Stocks tumbled today after a plan to alleviate a liquidity crisis at Bear Stearns touched off concerns about the severity of credit troubles.

Wall Street extended its 2008 plunge today, tumbling after a regional Federal Reserve report showed a sharp decline in manufacturing activity and as investors grew concerned that downgrades of key bond insurers could trigger further trouble with souring debt.