The investment seeks to reflect the daily changes in percentage terms of the spot price of light, sweet crude oil delivered to Cushing, Oklahoma, as measured by the daily changes in the average of the prices of specified short-term futures contracts on light, sweet crude oil called the ?Benchmark Oil Futures Contracts. The fund invests primarily in futures contracts for light, sweet crude oil, other types of crude oil, diesel-heating oil, gasoline, natural gas, and other petroleum-based fuels. The Benchmark Oil Futures Contracts are the futures contracts on light, sweet crude oil as traded on the New York Mercantile Exchange.