Bridgewater Associates, the biggest hedge fund in the entire planet, allegedly positioned a $1.5 billion bet that could produce a massive windfall for the fund as well as its shareholders if the stock market plunged before the end of March.

The gamble, or hedge, that has been made in recent months and, as per the Wall Street Journal, it is focusing on a decrease in the S&P 500-stock index of the biggest United States-based compan....