Treasury Secretary Henry Paulson stepped off the elevator into the Third Avenue offices of hedge fund Eton Park Capital Management LP in Manhattan. It was July 21, 2008, and market fears were mounting. Amid tumbling home prices and near-record foreclosures, attention was focused on a new source of contagion: Fannie Mae and Freddie Mac, which together had more than $5 trillion in mortgage-backed securities and other debt outstanding. Around the conference room table were a dozen or so hedge-fund managers and other Wall Street executives -- at least five of them alumni of Goldman Sachs Group Inc., of which Paulson was chief executive officer and chairman from 1999 to 2006. After a perfunctory discussion of the market turmoil ... the discussion turned to Fannie Mae and Freddie Mac. The secretary [desribed] a possible scenario for placing Fannie and Freddie into conservatorship" -- a government seizure designed to allow the firms to continue operations despite heavy losses in the mortgage markets. Paulson explained that under this scenario, the common stock of the two government-sponsored enterprises, or GSEs, would be effectively wiped out. So too would the various classes of preferred stock, he said ... leaving little doubt that the Treasury Department would carry out the plan. The managers attending the meeting were thus given a choice opportunity to trade on that information.