The investment seeks to track the investment results of the BlackRock High Yield Defensive Bond Index. The fund will invest at least 80% of its assets in the component securities of the underlying index and may invest up to 20% of its assets in certain index futures, options, options on index futures, swap contracts or other derivatives. The index consists of U.S. dollar-denominated, high yield corporate bonds. Component securities include publicly-issued debt of U.S. corporations and U.S. dollar-denominated, publicly issued debt of non-U.S. corporations or similar entities.