In seeking high current income exempt from regular federal income tax, the Fund will invest, under normal circumstances, at least 65% of its net assets in rated and unrated municipal instruments that are of low quality (commonly referred to as “junk bonds”) or medium or upper medium quality. A municipal instrument is a fixed-income obligation issued by a state, territory or possession of the United States (including the District of Columbia) or a political subdivision, agency or instrumentality thereof. Interest income received by holders of municipal instruments is often exempt from the federal income tax and from the income tax of the state in which they are issued, although municipal instruments issued for certain purposes may not be tax‑exempt. The municipal instruments in which the Fund invests may include:

Upper medium quality securities are rated A by a Nationally Recognized Statistical Rating Organization (“NRSRO”), and medium quality securities are rated BBB or Baa by a NRSRO.

Lower quality or below investment-grade securities are rated BB, Ba or lower by a NRSRO, or unrated securities determined to be of comparable quality by NTI. Credit ratings are determined at the time of purchase.

There is no minimum rating for a municipal instrument purchased or held by the Fund, and the Fund may purchase securities that are in default. Although the Fund primarily invests in low, medium or upper medium quality securities, it may invest a portion of its assets in securities of higher quality.

Except in extraordinary circumstances, at least 80% of the Fund’s net assets will be invested in debt instruments that pay interest that is exempt from regular federal income tax. The Fund is not limited in the amount of its assets that may be invested in alternative minimum tax (“AMT”) obligations (also known as “private activity bonds”), which pay interest that may be treated as an item of tax preference to shareholders under the federal AMT. For shareholders subject to AMT, a significant portion of the Fund’s dividends may be subject to federal tax.

In buying and selling securities for the Fund, NTI uses a relative value approach. This approach involves an analysis of general economic and market conditions. It also involves the use of models that analyze and compare expected returns and assumed risks. Under the relative value approach, NTI will emphasize particular securities and types of securities (such as corporate-backed municipal bonds and revenue obligation bonds) that NTI believes will provide a favorable return in light of these risks.

NTI may engage in active trading, and will not consider portfolio turnover a limiting factor in making decisions for the Fund.

The Fund does not have any portfolio maturity limitations, and may invest its assets from time to time primarily in instruments with short, medium or long maturities.