Taking the Other Side

... of the zero sum game, see this article at Financial Times:
1000% hedge fund wins subprime bet

The decision to use derivatives to short, or bet against, low-quality US home loans taken by a select group of hedge funds last year appears to have become the most profitable single trade of all time, making well over $20bn in total so far this year. John Paulson’s New York-based Paulson & Co, the biggest of the group with $28bn under management, is said by investors to have made $12bn profit from the trade already.
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“Our entire banking system is a complete disaster,” he wrote. “In my opinion, nearly every major bank would be insolvent if they marked their assets to market.” He also said he would be putting some of his own profits into gold and other precious metals.