The fund invests at least 80% of its assets (including borrowings for investment purposes) in bonds and other debt instruments ("80% Policy"). It invests principally in debt obligations issued or guaranteed by the U.S. government and by U.S. corporations. The U.S. government securities in which the fund may invest include a variety of securities that are issued or guaranteed as to the payment of principal and interest by the U.S. government, and by various agencies or instrumentalities that have been established or sponsored by the U.S. government.