The investment seeks the daily changes in percentage terms of its shares? per share NAV 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 price of a specified short-term futures contract on light, sweet crude oil called the ?Benchmark Oil Futures Contract,? plus interest earned on USO?s collateral holdings, less USO?s expenses. USO 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.