The Citigroup Bailout: What Are They Doing?

Paul Krugman has had enough:

Citigroup - Paul Krugman Blog - NYTimes.com: Mark Thoma has the rundown of informed reactions. A bailout was necessary — but this bailout is an outrage: a lousy deal for the taxpayers, no accountability for management, and just to make things perfect, quite possibly inadequate, so that Citi will be back for more. Amazing how much damage the lame ducks can do in the time remaining.

It is unclear to me why they aren't just buying common stock. As it is, they're endangering their own reputations to an extraordinary degree...