I think this whole thing was set up such that Institutions can buy much more than the $20 billion offering. Citi probably knows that there is huge demand for the shares (the 17x oversubscription may have some validity to it), but they can only issue so many shares. Therefore, by keeping the offering price low, institutions can load up on the open market even if they couldn't get into the offering. Many individual investors that don't know what's going on will sell with panic along the way...which effectively helps Citi take shares away from the average joe and transfer them to institutions. Pandit is really a hedge fund man afterall.