Dow has been down more than 200 points for much of the session. There's the usual concern about the economy - and jobs in particular - along with new worries about the European financial system. From the NYT:
The focus was on three countries: Greece, Portugal and Spain. The cost of insuring debt in those countries rose sharply on Thursday because swelling deficits could put them at risk for default. Greece's budget woes are considered the most grave. On Wednesday, European Union officials said the country might have to take more extreme measures to stabilize its finances. Investors have generally considered Greece's problems an isolated case. But new alarms were triggered on Thursday when Spain said its deficit might be worse than previously thought and officials in Portugal reported difficulty in selling treasury bills.