Strategy. American Century Investment Management, Inc. (the Sub-Adviser) serves as the Funds sub-adviser. The Sub-Adviser is responsible for the day-to-day management of the Funds assets. The Fund invests substantially all of its assets in investment-grade debt securities. An investment-grade security is one that has been rated by an independent rating agency in its top four credit quality categories or, if unrated, determined by the advisor to be of comparable credit quality. To help protect against U.S. inflation, under normal conditions the Fund will invest over 50% of its assets in inflation-indexed debt securities. These securities include inflation-indexed U.S. Treasury securities, inflation-indexed securities issued by U.S. government agencies and instrumentalities other than the U.S. Treasury, and inflation-indexed securities issued by other entities … Show more… American Century Investment Management, Inc. (the Sub-Adviser) serves as the Funds sub-adviser. The Sub-Adviser is responsible for the day-to-day management of the Funds assets. The Fund invests substantially all of its assets in investment-grade debt securities. An investment-grade security is one that has been rated by an independent rating agency in its top four credit quality categories or, if unrated, determined by the advisor to be of comparable credit quality. To help protect against U.S. inflation, under normal conditions the Fund will invest over 50% of its assets in inflation-indexed debt securities. These securities include inflation-indexed U.S. Treasury securities, inflation-indexed securities issued by U.S. government agencies and instrumentalities other than the U.S. Treasury, and inflation-indexed securities issued by other entities such as corporations and foreign governments. Inflation-indexed securities are designed to protect the future purchasing power of the money invested in them. The Fund also may invest in debt securities that are not inflation-indexed such as corporate bonds and notes, bank loans, commercial paper, and mortgage- or asset-backed securities. The Fund also may invest in derivative instruments, provided that such investments are in keeping with the Funds investment objective. For example, the Fund may use swap agreements to manage or reduce the risk of the effects of inflation with respect to the Funds position in non-inflation-indexed securities. The Fund also may enter into foreign currency exchange transactions for hedging purposes or to enhance returns. The Fund may also invest in collateralized debt obligations, collateralized loan obligations, and similarly structured investments. Under normal conditions, collateral loan obligations owned by the Fund may include covenant light loans. The Sub-Adviser is not limited to a specific weighted average maturity range. However, the Sub-Adviser monitors the Funds weighted average maturity and seek to adjust it as appropriate, taking into account market conditions, the current inflation rate and other relevant factors. Show less