Trader makes gutsy bet on a speedy market plunge

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Huge short-term bearish bet

One trader appears to be wagering half a million dollars that the market is headed much lower this week, in Wednesday's biggest single options trade of the day, in terms of the number of contracts traded.

Shortly after noon ET, the trader purchased 50,000 Jan. 23 weekly 195-strike puts on the popular SPDR exchange-traded fund tracking the S&P 500, which trades under the ticker symbol "SPY. " These options are perceived to have a low probability of paying off, which explains why they traded at a price of 9 cents a share, for a total outlay of $450,000.

That is the most the trader can lose, and as long as the SPY stays above $195 through Friday, the total amount will indeed be lost. However, if the S&P falls 5 percent between Wednesday at 2 p.m. ET and Friday's close (to give an example) the trader will enjoy a quick profit of more than $12 million.