I think it drops 100-200 points. I think people currently believe that the US government will approve some bailout plan in the near future. I don't think most people believe that the government will allow the bottom to fall out of the economy. It doesn't have to be tomorrow to avert a Great Depression.
Dangit! I posted "I predict that the Dow closes up 121 points" just after Minstrel posted "...we were both wrong."