My theory is the uncertainty tomorrow's fed decision may bring to banks, first, fed may stop paying intest on the reserve money. second, if fed rolls out OT, it shoots two birds, pushing down long term interest as well as beating down the short term treasuries to force out the huge money in the market, the latter may hurt the banks too.
It will be an outright surprise if we have a simple QE3, in this case I expect a huge rally in all assets except us long term treasuries.
It will be a huge surprise and dow may drop 500pts if fed does nothing.