Under normal circumstances, the fund invests at least 80% of its net assets (including the amount of any borrowings for investment purposes) in bonds and other debt securities. It generally invests at least 65% of its assets in debt securities issued by the U.S. government and its agencies and instrumentalities, debt securities issued by corporations, and mortgage- and other asset-backed securities that, at the time of purchase, are rated in at least one of the three highest rating categories or...