The investment seeks to provide total return that closely corresponds, before fees and expenses, to the total return of The BofA Merrill Lynch 15+ Year US Inflation-Linked Treasury IndexSM. The fund invests at least 80% of its total assets (exclusive of collateral held from securities lending) in the component securities ("Component Securities") of The BofA Merrill Lynch 15+ Year US Inflation-Linked Treasury IndexSM (the "underlying index"). The underlying index is an unmanaged index comprised of TIPS (Treasury Inflation Protected Securities) with a maturity of at least 15 years.