The PowerShares VRDO Tax-Free Weekly Portfolio (Fund) is based on the Bloomberg US Municipal AMT-Free Weekly VRDO Index (Index). The Fund generally will invest at least 80% of its total assets in variable rate demand obligation (VRDO) bonds that are exempt from federal income tax with interest rates that reset weekly, which comprise the Underlying Index. The Index is comprised of municipal securities issued in the primary market as VRDOs.VRDOs are floating-rate bonds that provide investors with tax-exempt income. VRDOs are generally purchased at par. When they are put back to an investment dealer, the investor generally receives par plus accrued interest. The Fund and the Index are rebalanced and reconstituted monthly.