The PowerShares S&P MidCap Low Volatility Portfolio (Fund) is based on the S&P MidCap 400 Low Volatility Index (Index). The Fund generally will invest at least 90% of its total assets in common stocks that comprise the Index. The Index is compiled, maintained and calculated by Standard & Poor's, consisting of 80 out of 400 medium-capitalization range securities from the S&P MidCap 400 Index with the lowest realized volatility over the past 12 months. Volatility is a statistical measurement of the magnitude of up and down asset price fluctuations over time. The Fund and the Index are rebalanced and reconstituted quarterly.