Strategy. To pursue its goal, the fund normally invests at least 80% of its net assets, plus any borrowings for investment purposes, in municipal bonds that provide income exempt from U.S. federal income tax. Municipal bonds are debt securities or other obligations issued by states, territories and possessions of the United States and the District of Columbia and their political subdivisions, agencies and instrumentalities, or multistate agencies and authorities. Municipal bonds typically are issued to finance public projects, but also may be issued for private activities. The fund's sub-adviser, Insight North America LLC, focuses on identifying undervalued sectors and securities. To select municipal bonds for the fund, the sub-adviser uses fundamental credit analysis to estimate the relative value and attractiveness of … Show more… To pursue its goal, the fund normally invests at least 80% of its net assets, plus any borrowings for investment purposes, in municipal bonds that provide income exempt from U.S. federal income tax. Municipal bonds are debt securities or other obligations issued by states, territories and possessions of the United States and the District of Columbia and their political subdivisions, agencies and instrumentalities, or multistate agencies and authorities. Municipal bonds typically are issued to finance public projects, but also may be issued for private activities. The fund's sub-adviser, Insight North America LLC, focuses on identifying undervalued sectors and securities. To select municipal bonds for the fund, the sub-adviser uses fundamental credit analysis to estimate the relative value and attractiveness of various sectors and securities and to exploit pricing inefficiencies in the municipal bond market. The sub-adviser actively trades among various sectors and securities, based on their apparent relative values. The fund seeks to invest in several different sectors and may overweight a particular sector depending on each sector's relative value at a given time. The fund typically invests in municipal and taxable bonds rated investment grade (i.e., Baa3/BBB- or higher) at the time of purchase or, if unrated, deemed of comparable quality by the fund's sub-adviser. Generally, the fund's average effective portfolio maturity will not exceed five years, and the average effective duration of the fund's portfolio will not exceed three years. The fund may invest in individual municipal and taxable bonds of any maturity or duration. A bond's maturity is the length of time until the principal must be fully repaid with interest. Average effective portfolio maturity is an average of the maturities of bonds held by the fund directly and the bonds underlying derivative instruments entered into by the fund, if any, adjusted to reflect provisions or market conditions that may cause a bond's principal to be repaid earlier than at its stated maturity. Duration is an indication of an investment's "interest rate risk," or how sensitive a bond or the fund's portfolio may be to changes in interest rates. Generally, the longer a bond's duration, the more likely it is to react to interest rate fluctuations and the greater its long-term risk/return potential. A rigorous sell discipline is employed to continuously evaluate all fund holdings. Current holdings may become sell candidates if creditworthiness is deteriorating, if bonds with better risk and return characteristics become available, or if the holding no longer meets the sub-adviser's strategic or portfolio construction objectives. Although the fund seeks to provide income exempt from U.S. federal income tax, income from some of the fund's holdings may be subject to the federal alternative minimum tax. Show less