The investment seeks daily investment results that correspond to the inverse (-1x) of the daily performance of the Dow Jones U.S. Oil & GasSM Index. The fund invests in financial instruments that ProShare Advisors believes, in combination, should produce daily returns consistent with the fund's investment objective. The index measures the performance of certain companies in the oil and gas sector of the U.S. equity market. Component companies include, among others, exploration and production, integrated oil and gas, oil equipment and services, pipelines, renewable energy equipment companies and alternative fuel producers. The fund is non-diversified.