The fund invests under normal circumstances at least 80% of its net assets (plus any borrowings for investment purposes) in the component securities of the ICE BofA 1-5 Year US Inflation-Linked Treasury Index (the index) and in derivatives and other instruments that have economic characteristics similar to such securities. The index is comprised of U.S. Treasury Inflation Protected Securities (TIPS) with at least $1 billion in outstanding face value and a remaining term to final maturity of at least 1 year and less than 5 years at the time of index rebalancing.