The fund is passively managed to invest across the entire long-term US Treasury spectrum (10 years and longer), excluding inflation-protected bonds. Its long effective duration, weighted average maturity and yield-to-maturity naturally exposes investors to higher interest rate risk, but not any more than is market-like. 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.