The fund provides exposure to floating-rate Treasury notes or FRNs. It tracks an index consisting of investment grade US Treasury floating rate notes with time-to-maturity greater than or equal to one month, initial maturity of up to two years, and a minimum issue size of $5 billion (excluding Federal Reserve holdings). The index excludes fixed-rate US Treasury bills, callable and non-callable securities, Treasury Inflation-Protected Securities (TIPS), and Separate Trading of Registered Interest and Principal of Securities (STRIPS). As FRNs reset their coupon rate weekly based on the most recent 90-day T-bill auction, they offer an extremely low-risk place to park ones cash with minimal interest-rate sensitivity, which should appeal to those concerned about potential rising rates. That also means reinvestment risk and low returns should rates fall. The index constituents are market value-weighted and rebalanced monthly on the last business day of the month.