The July 29, 2008, phone call between two titans of Wall Street began with the old friends exchanging mild pleasantries, but then quickly turned serious and - by the government's account - criminal. Hedge fund manager Raj Rajaratnam asked about a rumor that Goldman Sachs "might look to buy a commercial bank." On the other end of the phone, then-widely respected Goldman board member Rajat Gupta confided there was a "big discussion" on the subject at a recent meeting.