ProShares UltraPro MidCap400 (the Fund), seeks daily investment results, which correspond to triple (300%) the daily performance of the S&P MidCap 400 Index (the Index). The Index is used measure of mid-size company United States stock market performance. Companies are selected for inclusion in the Index by Standard & Poor's based on adequate liquidity, appropriate market capitalization, financial viability and public float. The investment adviser of the Fund is ProShare Advisors LLC .