The PowerShares Build America Bond Portfolio (Fund) is based on The BofA Merrill Lynch Build America Bond Index (Index). The Fund will normally invest at least 80% of its total assets in the securities that comprise the Index. The Index is designed to track the performance of US dollar-denominated Build America Bonds publicly issued by US states and territories, and their political subdivisions, in the US market. The Fund and the Index are rebalanced and reconstituted monthly.