The fund invests primarily in bonds and other debt instruments. The fund will normally invest at least 80 percent of its assets in, or derive at least 80 percent of its income from, securities that are exempt from regular federal income tax. The fund will invest up to 30 percent of its assets in securities that may subject you to federal alternative minimum tax. The fund invests at least 65 percent in debt securities rated BBB minus or better or Baa3 or better by Nationally Recognized Statistical Rating Organizations designated by the funds investment adviser, or unrated but determined by the funds investment adviser to be of equivalent quality. The fund may also invest in debt securities rated BB plus or below and Ba1 or below by Nationally Recognized Statistical Rating Organizations designated by the funds investment adviser, or unrated but determined by the funds investment adviser to be of equivalent quality. Securities rated BB plus or below and Ba1 or below are sometimes referred to as junk bonds. The fund may invest in debt securities of any maturity or duration.