Strategy. Under normal market conditions, the fund invests at least 80% of its net assets, plus amounts borrowed for investment purposes, in municipal bonds that pay interest exempt from federal income tax. Most of these securities are investment-grade, although the fund may invest up to 35% of its net assets in below-investment-grade debt securities (junk bonds) rated as low as CC by S&P Global Ratings (S&P) and Fitch Ratings, Inc. (Fitch Ratings) and Ca by Moodys Investors Service, Inc. (Moodys), or comparable rating by any nationally recognized statistical rating organization (NRSRO), or their unrated equivalents. Non-investment grade securities may also be referred to as below investment grade securities, commonly known as junk bonds. The fund may invest in fixed income securities … Show more… Under normal market conditions, the fund invests at least 80% of its net assets, plus amounts borrowed for investment purposes, in municipal bonds that pay interest exempt from federal income tax. Most of these securities are investment-grade, although the fund may invest up to 35% of its net assets in below-investment-grade debt securities (junk bonds) rated as low as CC by S&P Global Ratings (S&P) and Fitch Ratings, Inc. (Fitch Ratings) and Ca by Moodys Investors Service, Inc. (Moodys), or comparable rating by any nationally recognized statistical rating organization (NRSRO), or their unrated equivalents. Non-investment grade securities may also be referred to as below investment grade securities, commonly known as junk bonds. The fund may invest in fixed income securities which include bonds, debt securities and other similar instruments. The funds investment policies are based on credit ratings at the time of purchase. The fund may buy municipal bonds and other fixed income securities of any maturity. The fund will have an average effective duration of 4.5 years or less. Duration is a measure of the sensitivity of a fixed income securitys price to changes in interest rates. The fund may invest heavily in bonds from any given state or region and may have substantial investments in obligations of certain states and their agencies, instrumentalities, and/or political subdivisions. The manager may implement short-term trading strategies to take advantage of pricing imbalances within the municipal bond market. There is no guarantee that the manager will be able to implement these strategies effectively and the strategies may have a more significant impact on the fund's performance before it achieves scale. The fund may engage in derivative transactions that include futures contracts on debt securities and debt securities indexes; options on futures, debt securities, and debt indexes; and inverse floating-rate securities, in each case, for the purposes of reducing risk and/or enhancing investment returns. The fund may invest in general obligation bonds, however, in general, the manager favors bonds backed by revenue from a specific public project or facility, such as a power plant (revenue bonds), as they tend to offer higher yields than general obligation bonds. Show less