IUSB offers broad, plain-vanilla coverage of the USD-denominated bond market, which includes investment grade and high yield corporates, Treasurys, sovereigns, and MBS. The fund differs with those tracking the Bloomberg US Aggregate Index by allowing non-investment-grade issues. IUSB also allows sovereign debt and emerging-market bonds if they are issued in USD. As such, the fund can be riskier relative to more conservative and less market-like funds.