Felix Salmon is worried about $2 trillion behemoth Citigroup:

Citi might well turn out to be Hank Paulson's largest and biggest headache. There's no one he can sell it to -- it's far too big already. Which means that Paulson's only real option, if things deteriorate much further from here, is nationalization. Bits of it could be sold, at a price -- the retail bank to Santander, perhaps; other bits to JP Morgan or Goldman Sachs -- but the losses to the taxpayer would be enormous, and the disruption associated with breaking Citi up and then trying to integrate the pieces in the middle of a major financial crisis would likely be devastating to the economy.

Have a great day.