The investment seeks to track the performance of a market-weighted bond index with a long-term dollar-weighted average maturity. The fund invests by sampling the Index, meaning that it holds a range of Securities that, in the aggregate, approximates the full Index in terms of key risk factors and other characteristics and invests at least 80% of assets in bonds held in the Index. It maintains a dollar-weighted average maturity consistent with that of the Index, which generally ranges between 15 and 30 years.