What struck them powerfully was how cheaply the models allowed a person to speculate on situations that were likely to end in one of two dramatic ways. If, in the next year, a stock was going to be worth nothing or $100 a share, it was silly for anyone to sell a year-long option to buy the stock at $50 a share for $3. Yet the market often did something just like that. The model used by Wall Street to price trillions of dollars’ worth of derivatives thought of the financial world as an orderly, continuous process. But the world was not continuous; it changed discontinuously, and often by
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