The fund generally will invest at least 80% of its total assets in securities that comprise the underlying index. Strictly in accordance with its guidelines and mandated procedures, Invesco Indexing LLC compiles and maintains the underlying index. The index seeks to measure the performance of a portfolio of U.S. dollar-denominated investment-grade municipal bonds with maturities or, in some cases, “effective maturities,” in the year 2035. The fund is non-diversified.