BILS provides exposure to US Treasurys with maturities between 3-12 months. As such, BILS takes on less interest rate risk. The fund invests in USD-denominated, fixed rate T-bills and completes the issuers US Treasurys line-up consisting of bills, notes, and bonds. BIL is the shorter-term exposure with 1-3 months to maturity, SPTS at 1-3 years, SPTI at 3-10 years, and SPTL at 10 or more years to maturity. The underlying index is market value-weighted and undergoes a monthly rebalance.