The investment seeks to track the investment results of the Markit iBoxx Global Developed Markets High Yield Index. The fund generally will invest at least 90% of its assets in the component securities of the underlying index and may invest up to 10% of its assets in certain futures, options and swap contracts, cash and cash equivalents, including shares of money market funds advised by BFA or its affiliates. The index is a rules-based index consisting of high yield corporate bonds denominated in U.S. dollars, euros, British pounds sterling and Canadian dollars.