The investment seeks daily investment results, before fees and expenses, that correspond to two times the inverse (-2x) 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 seeks to measure the performance of certain companies in the oil and gas sector of the U.S. equity market. The fund is non-diversified.