The fund normally invests at least 80% of its net assets in investments issued or guaranteed by the U.S. government, its agencies or instrumentalities. It may invest in securities with credit quality above or below the credit rating of the U.S. government's long-term debt. The fund may also invest in investment grade corporate notes and bonds, collateralized loan obligations, zero-coupon bonds, securities issued pursuant to Rule 144A under the Securities Act of 1933, asset-backed securities and mortgage-related securities including mortgage dollar rolls, and etc.