The investment seeks daily investment results, before fees and expenses, that correspond to twice the inverse (-2x) of the daily performance of the Dow Jones U.S. Oil & GasSM Index. The fund invests in derivatives that ProShare Advisors believes, in combination, should have similar daily return characteristics as two times the inverse (-2x) of the daily return of the index. The index measures the performance of the oil and gas sector of the U.S. equity market. The fund is non-diversified.