Five senators sent a letter to the head of the Commodity Futures Trading Commission (CTFC) today, calling on him to restrict the trade of oil futures, citing rising gas prices as reason to limit investment.

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The senators wrote that the increasing price of oil futures is driving up the price of gasoline. Futures trading centers on the purchase and sale of oil at future prices, and investors essentially bet on how the price of oil will fluctuate. Over 99 percent of new investors are betting that the price of oil will go up, the senators wrote, resulting in a speculation bubble that has driven up the price of oil.