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. Four months earlier, Bear Stearns Cos. had sold itself for just $10 a share to JPMorgan Chase & Co. (JPM) 

Now, amid tumbling home prices and near-record foreclosures, attention was focused on a new source of contagion:  Fannie Mae (FNMA) and Freddie Mac, which together had more than $5 trillion in mortgage-backed securities and other debt outstanding, Bloomberg Markets reports in its January issue.

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