The investment seeks to track the investment results (before fees and expenses) of the Nasdaq BulletShares® USD Emerging Markets Debt 2021 Index (the underlying index). The fund generally will invest at least 80% of its total assets in securities that comprise the index. The index seeks to measure the performance of a portfolio of U.S. dollar-denominated emerging markets bonds with maturities or, in some cases, ?effective maturities? in the year 2021. The fund is non-diversified.