To pursue its goal, the fund generally invests in securities that are included in the Bloomberg US Treasury Inflation-Linked Bond Index (Series-L). The index includes all publicly issued U.S. Treasury Inflation-Protected Securities (TIPS) that have at least one year remaining to maturity, are rated investment grade and have dollar 500 million or more of outstanding face value. The TIPS in the index must be denominated in U.S. dollars and must be fixed rate and non-convertible. The index is market capitalization weighted and the TIPS in the index are updated on the last business day of each month. As of December 31, 2023, there were 48 TIPS in the index. TIPS are publicly issued, dollar denominated U.S. Government securities issued by the U.S. Treasury that have principal and interest payments linked to an official inflation measure (as measured by the Consumer Price Index, or CPI) and their payments are supported by the full faith and credit of the United States.