LONDON/NEW YORK -- Billions of dollars are pouring into oil exchange-traded funds as investors, many of them small savers more familiar with stocks than commodities, risk big losses and focus on the chance of huge rewards. Five of the biggest oil ETFs have seen their assets more than quadruple since July to $5.4 billion as the oil market has had a roller-coaster ride, collapsing by 60 percent then rallying by almost a third.

ETFs, designed for investors who cannot or will not buy and sell oil directly themselves, offer easy access and exposure to oil volatility because they are based on traded futures markets.

Many small investors such as pensioners, hobby traders, and savers on fixed incomes are attracted to oil ETFs, which can be designed to take advantage of price rises or falls.

But the volatility and structure of the underlying markets also make such investments dangerous for unwary investors.

"They can be quite dodgy," said a British woman who buys and sells oil derivatives from a rambling country house in western England using a trading platform run from a tax haven in the Caribbean.

"The smallest market difference can make you a lot of money - or a massive loss," she said, asking not to be identified.

One of the biggest risks for investors, particularly if they have "long-only" funds that buy and sell the front-end of futures, is the price structure of the underlying market.


If oil is rising in price and in short supply, futures markets may trade in "backwardation," with the front futures months at a premium to later months. When the front-month contract expires every four weeks, funds buy the second month and pocket the difference, earning a healthy profit.

But when futures markets have the opposite structure, a "contango" with the front months discounted to subsequent months, the process is reversed with funds having to pay out every month to buy the more expensive next months.