The fund normally invests at least 80% of its assets in debt securities whose interest is, in the opinion of bond counsel for the issuer at the time of issuance, exempt from regular federal income tax and California income tax. It invests primarily in investment grade debt securities, but may invest up to 10% of its total assets in high yield securities, as rated by Moody's, S&P or Fitch, or, if unrated, as determined by PIMCO.