Hedge funds and big Wall Street banks are taking advantage of loopholes in federal trading limits to buy massive amounts of oil contracts, ... helping to push oil prices to record highs. The federal agency that oversees oil trading, the Commodity Futures Trading Commission, has exempted these firms from rules that limit speculative buying. The CFTC has also waived regulations over the past decade on U.S. investors who trade commodities on some overseas markets, freeing those investors to accumulate large quantities of the future oil supply by making purchases on lightly regulated foreign exchanges. Over the past five years, investors have become such a force on commodity markets that their appetite for oil contracts has been equal to China's increase in demand over the same period, said Michael Masters, a hedge fund manager who testified before Congress on the subject last month. The commodity markets, he added, were never intended for such large financial players. Commodities have become especially enticing to investors as the credit crisis has roiled other investment opportunities such as stocks and debt-related securities. The recent flood of investment money has transformed the markets for oil, as well as uranium, wheat, cotton and other goods, into a volatile realm that some insiders call the Wild West of Wall Street. Michael Greenberger, a professor at the University of Maryland and former CFTC commissioner, said there were loopholes the agency could close without much effort. There's smoke here, and the CFTC hasn't wanted to look if there's a fire," he said. "But these are dark markets. They don't even know who's doing the trading."