AGZ tracks the agency sector of the US government bond market. Typically, when one thinks about government agencies, institutions like Fannie Mae come to mind. However, AGZ can hold a wide range of USD-denominated bonds, including corporates and foreign debt such as development banks guaranteed by the US government. AGZ holds slightly more short-term debt, resulting in a lower weighted average maturity but a higher YTM. However, these differences haven't had a significant impact on the fund's ability to deliver market-like exposure. The index is updated monthly. The fund uses a sampling method in tracking the index, which means it will invest in a sample of securities that collectively have an investment profile similar to that of the underlying index.