As filed with the U.S. Securities and Exchange Commission on August 28, 2020

1933 Act File No. 333-[    ]

1940 Act File No. 811-22391

U.S. SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form N-2

(Check appropriate box or boxes)

and/or

Nuveen Taxable Municipal Income Fund

(Exact name of Registrant as Specified in Charter)

333 West Wacker Drive, Chicago, Illinois 60606

(Address of Principal Executive Offices)

(Number, Street, City, State, Zip Code)

(Registrant’s Telephone Number, including Area Code): (312) 917-7700

Gifford R. Zimmerman

Vice President and Secretary

333 West Wacker Drive

Chicago, Illinois 60606

Name and Address (Number, Street, City, State, Zip Code) of Agent for Service

Copies to:

☒  Check box if any securities being registered on this Form will be offered on a delayed or continuous basis in reliance on Rule 415 under the Securities Act of 1933 (“Securities Act”), other than securities offered in connection with a dividend reinvestment plan.

☒  Check box if this Form is a registration statement pursuant to General Instruction A.2 or a post-effective amendment thereto.

It is proposed that this filing will become effective (check appropriate box)

☒  When declared effective pursuant to section 8(c)

Check each box that appropriately characterizes the Registrant:

☒  Registered Closed-End Fund (closed-end company that is registered under the Investment Company Act of 1940 (“Investment Company Act”)).

☒  A.2 Qualified (qualified to register securities pursuant to General Instruction A.2 of this Form).

The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment that specifically states this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until the Registration Statement shall become effective on such dates as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

THE INFORMATION IN THIS PROSPECTUS IS NOT COMPLETE AND MAY BE CHANGED. WE MAY NOT SELL THESE SECURITIES UNTIL THE REGISTRATION STATEMENT FILED WITH THE SECURITIES AND EXCHANGE COMMISSION IS EFFECTIVE. THIS PROSPECTUS IS NOT AN OFFER TO SELL THESE SECURITIES AND WE ARE NOT SOLICITING OFFERS TO BUY THESE SECURITIES IN ANY JURISDICTION WHERE THE OFFER OR SALE IS NOT PERMITTED.

SUBJECT TO COMPLETION

DATED [-], 2020

BASE PROSPECTUS

$[-]

Nuveen Taxable Municipal Income Fund

COMMON SHARES

PREFERRED SHARES

The Offerings. Nuveen Taxable Municipal Income Fund (the “Fund”) is offering, on an immediate, continuous or delayed basis, in one or more offerings, common shares (the “Common Shares”) or preferred shares (“Preferred Shares,” and the Common Shares and the Preferred Shares, collectively, the “Securities”). The Fund may offer and sell Securities to or through underwriters, through dealers or agents that the Fund designates from time to time, directly to purchasers or through a combination of these methods. In connection with any offering of Securities, the Fund will deliver a prospectus supplement describing such offering, including, as applicable, the names of any underwriters, dealers or agents and information regarding any applicable purchase price, fee, commission or discount arrangements made with those underwriters, dealers or agents or the basis upon which such amount may be calculated. For more information about the manners in which the Fund may offer Securities, see “Plan of Distribution.”

The Fund. This prospectus, together with any prospectus supplement, sets forth concisely information about the Fund that a prospective investor should know before investing, and should be retained for future reference. The Fund is a diversified, closed-end management investment company. The Fund’s primary investment objective is to provide current income through investments in taxable municipal securities. As a secondary objective, the Fund seeks to enhance portfolio value and total return. The Fund cannot assure you that it will achieve its investment objectives.

Common Shares are listed on the New York Stock Exchange (the “NYSE”) under the symbol “NBB.”

Investing in the Securities involves risks. See “Risk Factors” beginning on page 10. You should consider carefully these risks together with all of the other information in this prospectus and any related prospectus supplement before making a decision to purchase any of the Securities.

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[    ], 2020

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Fund Strategies and Policies. The Fund seeks to achieve its investment objectives by investing primarily in a diversified portfolio of taxable municipal securities. Under normal circumstances, the Fund will invest at least 80% of its Assets (as defined herein) in taxable municipal securities. The Fund may invest up to 20% of its Assets in securities other than taxable municipal securities, including municipal securities the interest income from which is exempt from regular federal income tax (sometimes referred to as “tax-exempt municipal securities”), U.S. Treasury securities and obligations of the U.S. Government, its agencies and instrumentalities. The Fund may purchase taxable municipal securities (including for purposes of the 80% test) and other tax-exempt municipal securities in the form of bonds, notes, leases or certificates of participation; structured as callable or non-callable; with payment forms that include fixed-coupon, variable rate, zero coupon, capital appreciation bonds, floating rate securities, inverse floating rate securities and other derivative instruments that replicate investment exposure to taxable municipal securities or other municipal securities. Such municipal securities may be acquired through investments in pooled vehicles, partnerships or other investment companies. The Fund may also purchase municipal securities representing a wide range of sectors and purposes. Under normal circumstances, the Fund will invest at least 80% of its Managed Assets (as defined herein) in securities that at the time of investment are investment grade quality. A security is considered investment grade quality if it is rated within the four highest letter grades (BBB or Baa or better) by at least one of the nationally recognized statistical rating organizations (“NRSROs”) that rate such security (even if it is rated lower by another), or if it is unrated by any NRSRO but judged to be of comparable quality by Nuveen Asset Management. Under normal circumstances, the Fund may invest up to 20% of its Managed Assets in securities rated below investment grade or are unrated by any NRSRO but judged to be of comparable quality by Nuveen Asset Management. Municipal securities of below investment grade quality are regarded as having predominantly speculative characteristics with respect to capacity to pay interest and repay principal, and are commonly referred to as junk bonds.

Leverage. The Fund uses leverage to pursue its investment objectives. The Fund may use leverage to the extent permitted by the Investment Company Act of 1940 (the “1940 Act”). The Fund may source leverage through a number of methods, including borrowings (including loans from financial institutions), issuances of debt securities, issuances of preferred shares of beneficial interest. The Fund may also use other forms of leverage including, but not limited to, reverse repurchase agreements and portfolio investments that have the economic effect of leverage, including, but not limited to, investments in inverse floating rate securities of tender option bond trusts. The Fund pays a management fee to Nuveen Fund Advisors (which in turn pays a portion of its fees to Nuveen Asset Management) based on a percentage of Managed Assets. Because Managed Assets for this purpose includes the assets acquired from the Fund’s use of leverage, Nuveen Fund Advisors and Nuveen Asset Management may have a conflict of interest in determining whether the Fund should use or increase leverage. See “Use of Leverage” and “The Fund’s Investments.” There is no assurance that the Fund’s leveraging strategy will be successful. Leverage involves special risks. See “Risk Factors—Leverage Risk.”

Beginning on January 1, 2021, as permitted by regulations adopted by the SEC, paper copies of the Fund’s shareholder reports will not be sent by mail, unless you specifically request paper copies of the shareholder reports from the Fund or from your financial intermediary, such as a broker-dealer or bank. Instead, shareholder reports will be available on the Fund’s website at http://www.nuveen.com, and you will be notified by mail each time a report is posted and provided with a website link to access the report. If you already elected to receive shareholder reports electronically, you will not be affected by this change and you need not take any action. You may elect to receive shareholder reports and other communications from the Fund electronically anytime by contacting your financial intermediary,

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such as a broker-dealer or bank, through which you hold your Common Shares. Shareholders may at any time elect to receive paper copies of the shareholder reports without charge by contacting your financial intermediary or by contacting the Fund by calling (800) 257-8787 or by writing to 333 West Wacker Drive, Chicago, Illinois 60606.

You should read this prospectus, together with any prospectus supplement, which contains important information about the Fund, before deciding whether to invest in Securities and retain it for future reference. A statement of additional information, dated [    ], 2020, and as it may be supplemented (the “SAI”), containing additional information about the Fund, has been filed with the SEC and is incorporated by reference in its entirety into this prospectus. You may request a free copy of the SAI, annual and semi-annual reports to shareholders when available and other information about the Fund and make shareholder inquiries by calling (312) 917-7700 or by writing to the Fund, or from the Fund’s website (www.nuveen.com). The information contained in, or that can be accessed through, the Fund’s website is not part of this prospectus, except to the extent specifically incorporated by reference in the SAI. You also may obtain a copy of the SAI (and other information regarding the Fund) from the SEC’s website (www.sec.gov).

The Securities do not represent a deposit or obligation of, and are not guaranteed or endorsed by, any bank or other insured depository institution, and are not federally insured by the Federal Deposit Insurance Corporation, the Federal Reserve Board or any other government agency.

Neither the U.S. Securities and Exchange Commission (the “SEC”) nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

TABLE OF CONTENTS

You should rely only on the information contained or incorporated by reference into this prospectus and any related prospectus supplement. The Fund has not authorized anyone to provide you with different information. If anyone provides you with different or inconsistent information, you should not rely on it. The Fund is not making an offer of Securities in any state where the offer is not permitted. You should not assume that the information contained in this prospectus and any related prospectus supplement is accurate as of any date other than the respective dates on the front covers. The Fund’s business, financial condition and prospects may have changed since that date.

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FORWARD-LOOKING STATEMENTS

Any projections, forecasts and estimates contained or incorporated by reference herein are forward looking statements and are based upon certain assumptions. Projections, forecasts and estimates are necessarily speculative in nature, and it can be expected that some or all of the assumptions underlying any projections, forecasts or estimates will not materialize or will vary significantly from actual results. Actual results may vary from any projections, forecasts and estimates and the variations may be material. Some important factors that could cause actual results to differ materially from those in any forward looking statements include changes in interest rates, market, financial or legal uncertainties, including changes in tax law, and the timing and frequency of defaults on underlying investments. Consequently, the inclusion of any projections, forecasts and estimates herein should not be regarded as a representation by the Fund or any of its affiliates or any other person or entity of the results that will actually be achieved by the Fund. Neither the Fund nor its affiliates has any obligation to update or otherwise revise any projections, forecasts and estimates including any revisions to reflect changes in economic conditions or other circumstances arising after the date hereof or to reflect the occurrence of unanticipated events, even if the underlying assumptions do not come to fruition. The Fund acknowledges that, notwithstanding the foregoing, the safe harbor for forward-looking statements under the Private Securities Litigation Reform Act of 1995 does not apply to investment companies such as the Fund.

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PROSPECTUS SUMMARY

This is only a summary. You should review the more detailed information contained elsewhere in this prospectus, in any prospectus supplement and in the statement of additional information, dated [            ], 2020, and as it may be supplemented (the “SAI”), including the documents incorporated by reference, prior to making an investment in the Fund, especially the information set forth under the heading “Risk Factors.”

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RISK FACTORS

Investing in the Securities involves risk, including the risk that you may receive little or no return on your investment or that you may lose part or all of your investment. The following discussion, together with the risk factors included in the applicable prospectus supplement, describes the principal risks associated with an investment in the Common Shares and Preferred Shares of the Fund.

Portfolio Level Risks

Municipal Securities Market Risk

Investing in the municipal securities market involves certain risks. The municipal securities market is one in which dealer firms make markets in bonds on a principal basis using their proprietary capital, and during periods of market turmoil these firms’ capital may be severely constrained. As a result, under such conditions, some firms may be unwilling to commit their capital to purchase and to serve as a dealer for municipal securities. The amount of public information available about the municipal securities in the Fund’s portfolio is generally less than that for corporate equities or bonds, and the Fund’s investment performance may therefore be more dependent on the analytical abilities of the Adviser and the Sub-Adviser than if the Fund were to invest in stocks or taxable bonds. The secondary market for municipal securities, particularly the below-investment-grade securities in which the Fund may invest, also tends to be less well-developed or liquid than many other securities markets, which may adversely affect the Fund’s ability to sell its municipal securities at attractive prices or at prices approximating those at which the Fund values them from time to time. Municipal securities may contain redemption provisions, which may allow the securities to be called or redeemed prior to their stated maturity, potentially resulting in the distribution of principal and a reduction in subsequent interest distributions.

The ability of municipal issuers to make timely payments of interest and principal may be diminished during general economic downturns and as governmental cost burdens are reallocated among federal, state and local governments. In addition, laws enacted in the future by Congress or state legislatures or by referenda could extend the time for payment of principal and/or interest or impose other constraints on the enforcement of such obligations or on the ability of municipalities to levy taxes. Further, some state and local governments have been and in the future may be subject to direct ballot referenda that could limit their financial flexibility, or their ability to levy taxes or raise tax revenues, which may adversely affect the marketability of notes and bonds issued by those state and local governments. Issuers of municipal securities might seek protection under the bankruptcy laws. In the event of bankruptcy of such an issuer, the Fund could experience delays in collecting principal and interest and the Fund may not, in all circumstances, be able to collect all principal and interest to which it is entitled. To enforce its rights in the event of a default in the payment of interest or repayment of principal, or both, the Fund may take possession of and manage the assets securing the issuer’s obligations on such securities, which may increase the Fund’s operating expenses. Any income derived from the Fund’s ownership or operation of such assets may not be of the type that would allow the Fund to continue to qualify as a regulated investment company for federal income tax purposes.

Revenue bonds issued by state or local agencies to finance the development of low-income, multi-family housing involve special risks in addition to those associated with municipal securities generally, including that the underlying properties may not generate sufficient income to pay expenses

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and interest costs. These bonds are generally non-recourse against the property owner, may be junior to the rights of others with an interest in the properties, may pay interest the amount of which changes based in part on the financial performance of the property, may be pre-payable without penalty and may be used to finance the construction of housing developments that, until completed and rented, do not generate income to pay interest. Additionally, unusually high rates of default on the underlying mortgage loans may reduce revenues available for the payment of principal or interest on such mortgage revenue bonds.

Special Risks Related to Certain Municipal Obligations

Municipal leases and certificates of participation involve special risks not normally associated with general obligations or revenue bonds. Leases and installment purchase or conditional sale contracts (which normally provide for title to the leased asset to pass eventually to the governmental issuer) have evolved as a means for governmental issuers to acquire property and equipment without meeting the constitutional and statutory requirements for the issuance of debt. The debt issuance limitations are deemed to be inapplicable because of the inclusion in many leases or contracts of “non-appropriation” clauses that relieve the governmental issuer of any obligation to make future payments under the lease or contract unless money is appropriated for such purpose by the appropriate legislative body on a yearly or other periodic basis. In addition, such leases or contracts may be subject to the temporary abatement of payments in the event that the governmental issuer is prevented from maintaining occupancy of the leased premises or utilizing the leased equipment. Although the obligations may be secured by the leased equipment or facilities, the disposition of the property in the event of non-appropriation or foreclosure might prove difficult, time consuming and costly, and may result in a delay in recovering or the failure to fully recover the Fund’s original investment. In the event of non-appropriation, the issuer would be in default and taking ownership of the assets may be a remedy available to the Fund, although the Fund does not anticipate that such a remedy would normally be pursued. To the extent that the Fund invests in unrated municipal leases or participates in such leases, the credit quality rating and risk of cancellation of such unrated leases will be monitored on an ongoing basis. Certificates of participation, which represent interests in unmanaged pools of municipal leases or installment contracts, involve the same risks as the underlying municipal leases. In addition, the Fund may be dependent upon the municipal authority issuing the certificates of participation to exercise remedies with respect to the underlying securities. Certificates of participation also entail a risk of default or bankruptcy, both of the issuer of the municipal lease and also the municipal agency issuing the certificate of participation.

Build America Bonds Risk

Build America Bonds are taxable municipal obligations issued pursuant to the American Recovery and Reinvestment Act of 2009 that are subject to federal subsidies of up to 35% of the interest payable on the bonds in the form of direct subsidies to the bond issuer or refundable tax credits to the bond holder. Build America Bonds are not guaranteed by the U.S. government or its agencies or instrumentalities. While the federal subsidy continues for the life of the bonds, provided that the issuer continues to meet all applicable program eligibility requirements, there is no assurance that the federal subsidy will be continued at original levels. Under the sequestration process under the Budget Control Act of 2011, automatic spending cuts that became effective on March 1, 2013 reduced the federal subsidy for BABs and other subsidized taxable municipal bonds. The reduced federal subsidy has been extended through 2024. The subsidy payments were reduced by 6.6% in 2018 and 6.2% in 2019. Further decreases in the level of the subsidy may impair the ability of issuers to make interest payments when due.

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Build America Bonds were an alternative form of financing to state and local governments whose primary means for accessing the capital markets had been through issuance of tax free municipal bonds. Pursuant to the terms of the American Recovery and Reinvestment Act of 2009, the issuance of Build America Bonds ceased on December 31, 2010. As a result, the availability of such bonds is limited and there can be no assurance that Build America Bonds will be actively traded. The market for the bonds and/or their liquidity may be negatively affected. Changes to the U.S. federal income tax laws that take effect in 2018 may affect the demand for and supply of taxable municipal bonds, including BABs.

Build America Bonds involve similar risks as traditional municipal bonds, including credit and market risk. Because certain states, including California, New York, Illinois, Texas and Ohio, were heavy issuers of BABs, the Fund may have a greater exposure to the economic or other factors affecting such states than a more diversified national municipal bond fund. In addition, should a Build America Bond’s issuer fail to continue to meet the applicable requirements, it is possible that such issuer may not receive federal cash subsidy payments, impairing the issuer’s ability to make scheduled interest payments. Build America Bonds may be subject to greater reinvestment risk, which is the risk that the Fund is unable to invest in bonds with similar yields, as BABs with attractive above-market purchase yields mature or are called.

Interest Rate Risk

Generally, when market interest rates rise, bond prices fall, and vice versa. Interest rate risk is the risk that the municipal securities in the Fund’s portfolio will decline in value because of increases in market interest rates. As interest rates decline, issuers of municipal securities may prepay principal earlier than scheduled, forcing the Fund to reinvest in lower yielding securities and potentially reducing the Fund’s income. As interest rates increase, slower-than-expected principal payments may extend the average life of securities, potentially locking-in a below-market interest rate and reducing the Fund’s value. In typical market interest rate environments, the prices of longer-term municipal securities generally fluctuate more than prices of shorter-term municipal securities as interest rates change. Because the Fund primarily invests in longer-term municipal securities, the common share net asset value and market price per share will fluctuate more in response to changes in market interest rates than if the Fund invested primarily in shorter-term municipal securities. Because the values of lower-rated and comparable unrated debt securities are affected both by credit risk and interest rate risk, the price movements of such lower grade securities typically have not been highly correlated to the fluctuations of the prices of investment-grade-quality securities in response to changes in market interest rates. The Fund’s use of leverage, as described herein, will tend to increase common share interest rate risk. There may be less governmental intervention in the securities markets in the near future. The negative impact on fixed-income securities if interest rates increase as a result could negatively impact the Fund’s net asset value.

Municipal Bond Market Liquidity Risk

Inventories of municipal bonds held by brokers and dealers have decreased in recent years, lessening their ability to make a market in these securities. This reduction in market making capacity has the potential to decrease the Fund’s ability to buy or sell bonds, and increase bond price volatility and trading costs, particularly during periods of economic or market stress. In addition, recent changes to federal banking regulations may cause certain dealers to reduce their inventories of municipal bonds, which may further decrease the Fund’s ability to buy or sell bonds. As a result, the Fund may be forced

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to accept a lower price to sell a security, to sell other securities to raise cash, or to give up an investment opportunity, any of which could have a negative effect on performance. If the Fund needed to sell large blocks of bonds, those sales could further reduce the bonds’ prices and hurt performance.

Credit Risk

Credit risk is the risk that one or more municipal securities in the Fund’s portfolio will decline in price, or the issuer thereof will fail to pay interest or principal when due, because the issuer of the security experiences a decline in its financial status. In general, lower-rated municipal securities carry a greater degree of risk that the issuer will lose its ability to make interest and principal payments, which could have a negative impact on the Fund’s NAV or dividends. Credit risk is increased when a portfolio security is downgraded or the perceived creditworthiness of the issuer deteriorates. If a municipal security satisfies the rating requirements described above at the time of investment and is subsequently downgraded below that rating, the Fund will not be required to dispose of the security. If a downgrade occurs, Nuveen Asset Management will consider what action, including the sale of the security, is in the best interests of the Fund and its shareholders. This means that the Fund may invest in municipal securities that are involved in bankruptcy or insolvency proceedings or are experiencing other financial difficulties at the time of acquisition (such securities are commonly referred to as distressed securities).

Below Investment Grade Risk

Municipal securities of below investment grade quality, commonly referred to as junk bonds, are regarded as having predominately speculative characteristics with respect to capacity to pay interest and repay principal when due, and are susceptible to default or decline in market value due to adverse economic and business developments. Also, to the extent that the rating assigned to a municipal security in the Fund’s portfolio is downgraded by any NRSRO, the market price and liquidity of such security may be adversely affected. The market values for municipal securities of below investment grade quality tend to be volatile, and these securities are less liquid than investment grade municipal securities. For these reasons, an investment in the Fund, compared with a portfolio consisting solely of investment grade securities, may experience the following:

Adverse changes in economic conditions are more likely to lead to a weakened capacity of a below investment grade issuer to make principal payments and interest payments compared to an investment grade issuer. The principal amount of below investment grade securities outstanding has proliferated in the past decade as an increasing number of issuers have used below investment grade

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securities for financing. The current downturn may severely affect the ability of highly leveraged issuers to service their debt obligations or to repay their obligations upon maturity. As the national economy experiences the current economic downturn, resulting in decreased tax and other revenue streams of municipal issuers, or in the event interest rates rise sharply, increasing the interest cost on variable rate instruments and negatively impacting economic activity, the number of defaults by below investment grade municipal issuers is likely to increase. Similarly, downturns in profitability in specific industries could adversely affect private activity bonds. The market values of lower quality debt securities tend to reflect individual developments of the issuer to a greater extent than do higher quality securities, which react primarily to fluctuations in the general level of interest rates. Factors having an adverse impact on the market value of lower quality securities may have an adverse impact on the Fund’s NAV and the market value of its Common Shares. In addition, the Fund may incur additional expenses to the extent it is required to seek recovery upon a default in payment of principal or interest on its portfolio holdings. In certain circumstances, the Fund may be required to foreclose on an issuer’s assets and take possession of its property or operations. In such circumstances, the Fund would incur additional costs in disposing of such assets and potential liabilities from operating any business acquired.

The secondary market for below investment grade securities may not be as liquid as the secondary market for more highly rated securities, a factor that may have an adverse effect on the Fund’s ability to dispose of a particular security. There are fewer dealers in the market for below investment grade municipal securities than the market for investment grade municipal securities. The prices quoted by different dealers for below investment grade municipal securities may vary significantly, and the spread between the bid and ask price is generally much larger for below investment grade municipal securities than for higher quality instruments. Under adverse market or economic conditions, the secondary market for below investment grade securities could contract further, independent of any specific adverse changes in the condition of a particular issuer, and these instruments may become illiquid. As a result, the Fund could find it more difficult to sell these securities or may be able to sell the securities only at prices lower than if such securities were widely traded. Prices realized upon the sale of such lower rated or unrated securities, under these circumstances, may be less than the prices used in calculating the Fund’s NAV.

Issuers of below investment grade securities are highly leveraged and may not have available to them more traditional methods of financing. Therefore, the risk associated with acquiring the securities of such issuers generally is greater than is the case with higher rated securities. For example, during an economic downturn or a sustained period of rising interest rates, highly leveraged issuers of below investment grade securities may experience financial stress. During such periods, such issuers may not have sufficient revenues to meet their interest payment obligations. The issuer’s ability to service its debt obligations also may be adversely affected by specific developments, the issuer’s inability to meet specific projected forecasts or the unavailability of additional financing. The risk of loss from default by the issuer is significantly greater for the holders of below investment grade securities because such securities are generally unsecured and are often subordinated to other creditors of the issuer. Prices and yields of below investment grade securities will fluctuate over time and, during periods of economic uncertainty, volatility of below investment grade securities may adversely affect the Fund’s NAV. In addition, investments in below investment grade zero coupon bonds rather than income-bearing below investment grade securities, may be more speculative and may be subject to greater fluctuations in value due to changes in interest rates.

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The Fund may invest in the securities of an issuer which, at the time of investment, is in default on its obligations to pay principal or interest thereon when due or that is involved in a bankruptcy proceeding (i.e., rated below C- at the time of investment), and may invest in municipal securities that are experiencing other financial difficulties at the time of acquisition (such securities are commonly referred to as distressed securities). The issuers of such securities may be in transition, out of favor, financially leveraged or troubled, or potentially troubled, and may be or have recently been involved in major strategic actions, restructurings, bankruptcy, reorganization or liquidation. These characteristics of these companies can cause their securities to be particularly risky, although they also may offer the potential for high returns. These companies’ securities may be considered speculative, and the ability of the companies to pay their debts on schedule could be affected by adverse interest rate movements, changes in the general economic climate, economic factors affecting a particular industry or specific developments within the companies. Distressed securities frequently do not produce income while they are outstanding and may require the Fund to bear certain extraordinary expenses in order to protect and recover its investment.

Income Risk

The Fund’s income is based primarily on the interest it earns from its investments, which can vary widely over the short term and long term. If interest rates drop, the Fund’s income available over time to make dividend payments could drop as well if the Fund purchases securities with lower interest coupons.

Call Risk or Prepayment Risk

During periods of declining interest rates or for other purposes, issuers of callable bonds with higher interest coupons may exercise their option to “call” (or prepay) bonds before their maturity date, forcing the Fund to reinvest in lower yielding securities.

Reinvestment Risk

Reinvestment risk is the risk that the income from the Fund’s portfolio will decline if and when the Fund invests the proceeds from matured, traded or called bonds at market interest rates that are below the current earnings rate of the Fund’s portfolio. A decline in income could affect the ability of the Fund to pay dividends on its common shares, as well as the common shares’ market price or overall returns.

Inverse Floating Rate Securities Risk

Typically, inverse floating rate securities represent beneficial interests in TOB trusts that hold municipal bonds. In general, income on inverse floating rate securities will decrease when interest rates increase and increase when interest rates decrease. Investments in inverse floating rate securities may subject the Fund to the risks of reduced or eliminated interest payments and losses of principal in respect of the underlying municipal bonds.

In the case of certain TOB trusts, neither the holders of the associated floating rate securities nor the TOB trust itself have recourse to the holder of the inverse floating rate securities for losses on the underlying municipal bonds. In that case, the risk of loss to the Fund generally is limited to its investment in such securities. However, in certain circumstances and in the Sub-Adviser’s discretion,

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the Fund may enter into a recourse arrangement with the liquidity provider to a TOB trust in the form of a separate shortfall and forbearance agreement by which the Fund will agree to reimburse the liquidity provider for any amounts paid by it under the liquidity facility. The Fund may enter into such recourse agreements: (1) when the liquidity provider to the TOB trust requires such an agreement because the level of leverage in the trust exceeds the level that the liquidity provider is willing to support absent such an agreement; and/or (2) to seek to prevent the liquidity provider from collapsing the trust in the event that the underlying municipal bond held in the trust has declined in value to the point where it may cease to exceed the face amount of outstanding short-term floaters. Such an agreement would require the Fund to reimburse the liquidity provider, among other amounts, upon termination of the TOB trust for the shortfall of the liquidation value of the bonds held in the trust relative to the amount of principal and unpaid interest due to the holders of floating rate securities. In such instances, the Fund may be at risk of loss that exceeds its investment in the inverse floating rate securities.

Inverse floating rate securities may increase or decrease in value at a greater rate than the underlying municipal bonds, which effectively leverages the Fund’s investment. As a result, the market value of such securities generally will be more volatile than that of otherwise comparable municipal bonds held on an unleveraged basis outside a TOB trust.

The Fund may invest in inverse floating rate securities issued by TOB trusts in which the liquidity provider has recourse to the Fund (a “recourse TOB trust”) to the extent that the value of the bonds deposited in the TOB trust may fall in value below the principal amount of the short-term floating rate securities issued by that trust. The inverse floating rate securities issued by such recourse TOB trusts may be highly leveraged. The structure and degree to which the Fund’s inverse floating rate securities are highly leveraged will vary based upon a number of factors, including the size of the trust itself and the terms of the underlying municipal bonds. An inverse floating rate security generally is considered highly leveraged if the ratio of (1) the principal amount of the short-term floating rate securities issued by the TOB trust to (2) the principal amount of that TOB trust’s inverse floating rate securities equals or exceeds 3:1. In the event of a significant decline in the value of an underlying municipal bond held in a recourse TOB trust, the Fund may suffer losses in excess of the amount of its investment in the inverse floating securities (typically up to an amount equal to the outstanding face amount of such municipal bonds) as a result of liquidating the trust.

The Fund’s investment in inverse floating rate securities will create effective leverage, used in pursuit of increased common share net income and returns. But such effective leverage could reduce common share income (such as if the interest rate paid on the short-term floating rate securities were to exceed the interest rate being received on the municipal bonds underlying the TOB trust, net of trust expenses, for a meaningful period of time), and could also diminish common share long-term returns (such as if the value of the municipal bonds underlying the TOB trust were to decline in value by more than any positive differential between the income being earned on those underlying bonds, net of trust expenses, relative to the interest being paid to the holders of the short-term floating rate securities issued by that trust).

The amount of fees paid to the Adviser (which in turn pays a portion of its fees to the Sub-Adviser) for investment advisory services will be higher when the Fund uses leverage because the advisory fees are calculated based on the Fund’s managed assets. This may create an incentive for the Adviser and/or the Sub-Adviser to leverage the Fund.

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Inverse floating rate securities have varying degrees of liquidity based, among other things, upon the liquidity of the underlying municipal bonds deposited in the TOB trust.

The leverage attributable to inverse floating rate securities may be “called away” on relatively short notice and therefore may be less permanent than more traditional forms of leverage. In certain circumstances, the likelihood of an increase in the volatility of net asset value and market price of the common shares may be greater for the Fund that relies primarily on inverse floating rate securities to achieve a desired effective leverage ratio. The Fund may be required to sell its inverse floating rate securities at less than favorable prices or to liquidate other Fund portfolio holdings in certain circumstances, including, but not limited to, the following:

There is no assurance that the Fund’s strategy of investing in inverse floating rate securities will be successful.

Reverse Repurchase Agreement Risk

Reverse repurchase agreements involve the sale of securities held by the Fund with an agreement to repurchase the securities at an agreed-upon price, date and interest payment, and represent borrowings of the Fund. Reverse repurchase agreements involve the risk that the other party to the agreement may fail to return the securities in a timely manner or at all. The Fund could lose money if it is unable to recover the securities and the value of the collateral held by the Fund, including the value of investments made with cash collateral, is less than the value of the securities. These events could also trigger adverse tax consequences to the Fund. The use by the Fund of reverse repurchase agreements involves many of the same risks of leverage since the proceeds derived from such reverse repurchase agreements may be invested in additional securities.

Insurance Risk

The Fund may purchase municipal securities that are secured by insurance, bank credit agreements or escrow accounts. The credit quality of the companies that provide such credit enhancements will affect the value of those securities. During and following the 2007–2009 financial crisis, certain significant providers of insurance for municipal securities incurred significant losses as a result of exposure to sub-prime mortgages and other lower credit quality investments that experienced defaults or otherwise suffered extreme credit deterioration. Such losses reduced the insurers’ capital and called into question their continued ability to perform their obligations under such insurance should they be called upon to do so. While an insured municipal security will typically be deemed to have the rating of its insurer, if the insurer of a municipal security suffers a downgrade in its credit rating or the market discounts the value of the insurance provided by the insurer, the rating of the underlying municipal security will be more relevant and the value of the municipal security would more closely, if not entirely, reflect such rating. In such a case, the value of insurance associated with a

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municipal security would decline and may not add any value. The insurance feature of a municipal security does not guarantee the full payment of principal and interest through the life of an insured obligation, the market value of the insured obligation or the net asset value of the common shares represented by such insured obligation.

Tax Risk

To qualify for the favorable U.S. federal income tax treatment generally accorded to regulated investment companies, among other things, the Fund must derive in each taxable year at least 90% of its gross income from certain prescribed sources and satisfy a diversification test on a quarterly basis. If the Fund fails to satisfy the qualifying income or diversification requirements in any taxable year, the Fund may be eligible for relief provisions if the failures are due to reasonable cause and not willful neglect and if a penalty tax is paid with respect to each failure to satisfy the applicable requirements. Additionally, relief is provided for certain de minimis failures of the diversification requirements where the Fund corrects the failure within a specified period. In order to be eligible for the relief provisions with respect to a failure to meet the diversification requirements, the Fund may be required to dispose of certain assets. If these relief provisions are not available to the Fund and it fails to qualify for treatment as a regulated investment company, all of its taxable income (including its net capital gains) would be subject to federal income tax at regular corporate rates without any deduction for distributions to shareholders, and all distributions from the Fund would be taxable to shareholders as ordinary dividends to the extent of the Fund’s current and accumulated earnings and profits.

Inflation Risk

Inflation is the reduction in the purchasing power of money resulting from the increase in the price of goods and services. Inflation risk is the risk that the inflation-adjusted (or “real”) value of assets or income from investment will be worth less in the future. As inflation increases, the real value of common shares and distributions can decline. In addition, during any period of rising inflation, interest rates on borrowings would likely increase, which would tend to further reduce returns to common shareholders.

Deflation Risk

Deflation risk is the risk that prices throughout the economy decline over time—the opposite of inflation risk. Deflation may have an adverse effect on the creditworthiness of issuers and may make issuer default more likely, which may result in a decline in the value of the Fund’s portfolio.

Derivatives Risk, Including the Risk of Swaps

The Fund’s use of derivatives involves risks different from, and possibly greater than, the risks associated with investing directly in the investments underlying the derivatives, including: the imperfect correlation between the value of such instruments and the underlying assets of the Fund, which creates the possibility that the loss on such instruments may be greater than the gain in the value of the underlying assets in the Fund’s portfolio; the loss of principal; the possible default of the other party to the transaction; and illiquidity of the derivative investments. If the Fund enters into certain derivatives transactions, it could lose more than the principal amount invested. Whether the Fund’s use of derivatives is successful will depend on, among other things, if the Adviser and/or the Sub-Adviser

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correctly forecast market values, interest rates and other applicable factors. If the Adviser and/or the Sub-Adviser incorrectly forecast these and other factors, the investment performance of the Fund will be unfavorably affected.

The Fund may enter into debt-related derivative instruments including credit default swap contracts and interest rate swaps. Like most derivative instruments, the use of swaps is a highly specialized activity that involves investment techniques and risks different from those associated with ordinary portfolio securities transactions. In addition, the use of swaps requires an understanding by the Adviser and/or the Sub-Adviser of not only the referenced asset, rate or index, but also of the swap itself. The derivatives markets are subject to a changing regulatory environment. It is possible that regulatory or other developments in the derivatives markets could adversely affect the Fund’s ability to successfully use derivative instruments.

Furthermore, derivative investments may be illiquid. Although both OTC and exchange-traded derivatives markets may experience a lack of liquidity, OTC non-standardized derivatives transactions are generally less liquid than exchange-traded instruments. The illiquidity of the derivatives markets may be due to various factors, including congestion, disorderly markets, limitations on deliverable supplies, the participation of speculators, government regulation and intervention, and technical and operational or system failures. In addition, the liquidity of a secondary market in an exchange-traded derivative contract may be adversely affected by “daily price fluctuation limits” established by the exchanges which limit the amount of fluctuation in an exchange-traded contract price during a single trading day. Once the daily limit has been reached in the contract, no trades may be entered into at a price beyond the limit, thus preventing the liquidation of open positions. Prices have in the past moved beyond the daily limit on a number of consecutive trading days. If it is not possible to close an open derivative position entered into by the Fund, the Fund would continue to be required to make cash payments of variation (or mark-to-market) margin in the event of adverse price movements. In such a situation, if the Fund has insufficient cash, it may have to sell portfolio securities to meet variation margin requirements at a time when it may be disadvantageous to do so. The absence of liquidity may also make it more difficult for the Fund to ascertain a market value for such instruments. The inability to close futures or derivatives positions also could have an adverse impact on the Fund’s ability to effectively hedge its portfolio.

Derivatives Regulatory Risk

Future regulatory developments could impact the Fund’s ability to invest in certain derivatives. It is possible that government regulation of various types of derivative instruments, including futures, options and swap agreements, may limit or prevent the Fund from using such instruments as a part of its investment strategies, and could ultimately prevent the Fund from being able to achieve its investment objectives. It is impossible to fully predict the effects of past, present or future legislation and regulation in this area, but the effects could be substantial and adverse. There is a likelihood of future regulatory developments altering, perhaps to a material extent, the nature of an investment in the Fund or the ability of the Fund to continue to implement its investment strategies. It is possible that legislative and regulatory activity could limit or restrict the ability of the Fund to use certain instruments as a part of its investment strategies. Limits or restrictions applicable to the counterparties with which the Fund engages in derivatives transactions (for example, the Volcker Rule) could also prevent the Fund from using certain instruments.

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The Dodd-Frank Act sets forth a regulatory framework for OTC derivatives, including financial instruments, such as swaps, in which the Fund may invest. The Dodd-Frank Act grants significant authority to the SEC and the CFTC to regulate OTC derivatives and market participants and requires clearing and exchange trading of many current OTC derivatives transactions. The implementation of the provisions of the Dodd-Frank Act by the SEC and the CFTC could adversely affect the Fund’s ability to pursue its investment strategies. The Dodd-Frank Act and the rules promulgated thereunder could, among other things, adversely affect the value of the investments held by the Fund, restrict the Fund’s ability to engage in derivatives transactions and/or increase the costs of such derivatives transactions.

Further, in February 2012, the CFTC issued a final rule rescinding and amending certain exemptions from registration requirements under the U.S. Commodity Exchange Act, as amended (the “CEA”), previously available to investment advisers registered with the SEC under the 1940 Act, including the exemption available under CFTC Rule 4.5. In the event that the Fund’s investments in derivative instruments regulated under the CEA, including futures, swaps and options, exceed a certain threshold, the Adviser and/or the Sub-Adviser may be required to register as a “commodity pool operator” and/or a “commodity trading advisor” with the CFTC. In the event the Adviser and/or the Sub-Adviser is required to register with the CFTC, it will become subject to additional recordkeeping and reporting requirements with respect to the Fund, which may increase the Fund’s expenses.

Hedging Risk

The Fund’s use of derivatives or other transactions to reduce risk involves costs and will be subject to the Adviser’s and/or the Sub-Adviser’s ability to predict correctly changes in the relationships of such hedge instruments to the Fund’s portfolio holdings or other factors. No assurance can be given that the Adviser’s and/or the Sub-Adviser’s judgment in this respect will be correct, and no assurance can be given that the Fund will enter into hedging or other transactions at times or under circumstances in which it may be advisable to do so. Hedging activities may reduce the Fund’s opportunities for gain by offsetting the positive effects of favorable price movements and may result in net losses.

Other Investment Companies Risk

An investment in the securities of another investment company will expose the Fund to the risks of investing in the securities held in such other investment company’s portfolio. In addition, the Fund’s shareholders will bear their proportionate share of the fees and expenses of such other investment company in addition to the fees and expenses of the Fund. The securities of other investment companies may also be leveraged. As a result, the Fund may be indirectly exposed to leverage through an investment in such securities. Utilization of leverage is a speculative investment technique and involves certain risks. An investment in securities of other investment companies that are leveraged may expose the Fund to higher volatility in the market value of such securities and the possibility that the Fund’s long-term returns on such securities will be diminished.

Illiquid Securities Risk

Illiquid securities are securities that are not readily marketable and may include restricted securities, which are securities that may not be resold unless they have been registered under the Securities Act of 1933, as amended (the “Securities Act”), or that can be sold in a private transaction

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pursuant to an available exemption from such registration. Illiquid securities involve the risk that the securities will not be able to be sold at the time desired by the Fund or at prices approximating the value at which the Fund is carrying the securities on its books from time to time.

Other Risks

Economic and Political Events Risk

The Fund may be more sensitive to adverse economic, business or political developments if it invests a substantial portion of its assets in the bonds of similar projects (such as those relating to the education, health care, housing, transportation, or utilities industries), industrial development bonds, or in particular types of municipal securities (such as general obligation bonds, private activity bonds or moral obligation bonds). Such developments may adversely affect a specific industry or local political and economic conditions, and thus may lead to declines in the bonds’ creditworthiness and value.

Global Economic Risk

National and regional economies and financial markets are becoming increasingly interconnected, which increases the possibilities that conditions in one country, region or market might adversely impact issuers in a different country, region or market. Changes in legal, political, regulatory, tax and economic conditions may cause fluctuations in markets and securities prices around the world, which could negatively impact the value of the Fund’s investments. Major economic or political disruptions, particularly in large economies like China’s, may have global negative economic and market repercussions. Additionally, the aftermath of the war in Iraq, instability in Afghanistan, Pakistan, Egypt, Libya, Syria, Russia, Ukraine and the Middle East, natural and environmental disasters and the spread of infectious illnesses or other public health emergencies, possible terrorist attacks in the United States and around the world, continued tensions between North Korea and the United States and the international community generally, growing social and political discord in the United States, the European debt crisis, the response of the international community—through economic sanctions and otherwise—to Russia’s annexation of the Crimea region of Ukraine and posture vis-a-vis Ukraine, further downgrade of U.S. Government securities, the change in the U.S. president and the new administration and other similar events may adversely affect the global economy and the markets and issuers in which the Fund invests. Recent examples of such events include the outbreak of a novel coronavirus known as COVID-19 that was first detected in China in December 2019 and heightened concerns regarding North Korea’s nuclear weapons and long-range ballistic missile programs. These events could reduce consumer demand or economic output, result in market closure, travel restrictions or quarantines, and generally have a significant impact on the economy. These events could also impair the information technology and other operational systems upon which the Fund’s service providers, including Nuveen Asset Management, rely, and could otherwise disrupt the ability of employees of the Fund’s service providers to perform essential tasks on behalf of the Fund. Additionally, the recent outbreak of COVID-19 has adversely impacted global commercial activity and has contributed to significant volatility in certain financial markets. There are no comparable recent events in the U.S. that provide guidance as to the effect of the spread of COVID-19 and a potential pandemic on the economy as a whole and, consequently, the Fund. Accordingly, while there have been proposed, and in some cases enacted, economic stimulus measures aimed at curbing the negative economic impacts to the U.S. and other countries as a result of COVID-19, it cannot be determined at this time whether such stimulus measures will have a stabilizing economic effect. The Fund does not know and can not predict how long the securities markets may be affected by these

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events and the effects of these and similar events in the future on the U.S. economy and securities markets. The Fund may be adversely affected by abrogation of international agreements and national laws which have created the market instruments in which the Fund may invest, failure of the designated national and international authorities to enforce compliance with the same laws and agreements, failure of local, national and international organizations to carry out their duties prescribed to them under the relevant agreements, revisions of these laws and agreements which dilute their effectiveness or conflicting interpretation of provisions of the same laws and agreements.

Governmental and quasi-governmental authorities and regulators throughout the world have in the past responded to major economic disruptions with a variety of significant fiscal and monetary policy changes, including but not limited to, direct capital infusions into companies, new monetary programs and dramatically lower interest rates. An unexpected or quick reversal of these policies, or the ineffectiveness of these policies, could increase volatility in securities markets, which could adversely affect the Fund’s investments. See “—Recent Market Conditions” below.

Recent Market Conditions

In response to the financial crisis and recent market events, the United States and other governments and the Federal Reserve and certain foreign central banks have taken steps to support financial markets. Policy and legislative changes by the United States government and the Federal Reserve to assist in the ongoing support of financial markets, both domestically and in other countries, are changing many aspects of financial regulation. The impact of these changes on the markets, and the practical implications for market participants, may not be fully known for some time. In some countries where economic conditions are recovering, such countries are nevertheless perceived as still fragile. Withdrawal of government support, failure of efforts in response to the crisis, or investor perception that such efforts are not succeeding, could adversely impact the value and liquidity of certain securities. The severity or duration of adverse economic conditions may also be affected by policy changes made by governments or quasi-governmental organizations, including changes in tax laws and the imposition of trade barriers. The impact of new financial regulation legislation on the markets and the practical implications for market participants may not be fully known for some time. Changes to the Federal Reserve policy, including with respect to certain interest rates, may affect the value, volatility and liquidity of dividend and interest paying securities. Regulatory changes are causing some financial services companies to exit long-standing lines of business, resulting in dislocations for other market participants. In addition, the contentious domestic political environment, as well as political and diplomatic events within the United States and abroad, such as the U.S. government’s inability at times to agree on a long-term budget and deficit reduction plan, the threat of a federal government shutdown and threats not to increase the federal government’s debt limit, may affect investor and consumer confidence and may adversely impact financial markets and the broader economy, perhaps suddenly and to a significant degree. The U.S. government has recently reduced the federal corporate income tax rate, and future legislative, regulatory and policy changes may result in more restrictions on international trade, less stringent prudential regulation of certain players in the financial markets, and significant new investments in infrastructure and national defense. Markets may react strongly to expectations about the changes in these policies, which could increase volatility, especially if the markets’ expectations for changes in government policies are not borne out.

Changes in market conditions will not have the same impact on all types of securities. Interest rates have been unusually low in recent years in the United States and abroad, but there is a consensus that interest rates will increase during the life of the Fund, which could negatively impact the price of

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debt securities. Because there is little precedent for this situation, it is difficult to predict the impact of a significant rate increase on various markets. For example, because investors may buy securities or other investments with borrowed money, a significant increase in interest rates may cause a decline in the markets for those investments. Because of the sharp decline in the worldwide price of oil, there is a concern that oil producing nations may withdraw significant assets now held in U.S. Treasuries, which could force a substantial increase in interest rates. Regulators have expressed concern that rate increases may cause investors to sell fixed income securities faster than the market can absorb them, contributing to price volatility. In addition, there is a risk that the prices of goods and services in the United States and many foreign economies may decline over time, known as deflation (the opposite of inflation). Deflation may have an adverse effect on stock prices and creditworthiness and may make defaults on debt more likely. If a country’s economy slips into a deflationary pattern, it could last for a prolonged period and may be difficult to reverse.

On June 23, 2016, the United Kingdom (“UK”) held a referendum on whether to remain a member state of the European Union (“EU”), in which voters favored the UK’s withdrawal from the EU, an event widely referred to as “Brexit” and which triggered a two-year period of negotiations on the terms of withdrawal. The formal notification to the European Council required under Article 50 of the Treaty on EU was made on March 29, 2017, following which the terms of exit were negotiated. On January 31, 2020, the UK formally withdrew from the EU. The longer term economic, legal, political and social framework to be put in place between the UK and the EU are unclear at this stage, remain subject to negotiation and are likely to lead to ongoing political and economic uncertainty and periods of exacerbated volatility in both the UK and in wider European markets for some time. The outcomes may cause increased volatility and have a significant adverse impact on world financial markets, other international trade agreements, and the UK and European economies, as well as the broader global economy for some time. Additionally, a number of countries in Europe have suffered terror attacks, and additional attacks may occur in the future. Ukraine has experienced ongoing military conflict; this conflict may expand and military attacks could occur elsewhere in Europe. Europe has also been struggling with mass migration from the Middle East and Africa. The ultimate effects of these events and other socio-political or geographical issues are not known but could profoundly affect global economies and markets.

The current political climate has intensified concerns about a potential trade war between China and the United States, as each country has recently imposed tariffs on the other country’s products. These actions may trigger a significant reduction in international trade, the oversupply of certain manufactured goods, substantial price reductions of goods and possible failure of individual companies and/or large segments of China’s export industry, which could have a negative impact on the Fund’s performance. U.S. companies that source material and goods from China and those that make large amounts of sales in China would be particularly vulnerable to an escalation of trade tensions. Uncertainty regarding the outcome of the trade tensions and the potential for a trade war could cause the U.S. dollar to decline against safe haven currencies, such as the Japanese yen and the euro. Events such as these and their consequences are difficult to predict and it is unclear whether further tariffs may be imposed or other escalating actions may be taken in the future.

The impact of these developments in the near- and long-term is unknown and could have additional adverse effects on economies, financial markets and asset valuations around the world.

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Legislation and Regulatory Risk

At any time after the date of this prospectus, legislation or additional regulations may be enacted that could negatively affect the assets of the Fund, securities held by the Fund or the issuers of such securities. Changing approaches to regulation may have a negative impact on the entities and/or securities in which the Fund invests. Legislation or regulation may also change the way in which the Fund itself is regulated. Fund shareholders may incur increased costs resulting from such legislation or additional regulation. There can be no assurance that future legislation, regulation or deregulation will not have a material adverse effect on the Fund or will not impair the ability of the Fund to achieve its investment objective.

For example, the Dodd-Frank Act is designed to impose stringent regulation on the over-the-counter derivatives market in an attempt to increase transparency and accountability and provides for, among other things, new clearing, execution, margin, reporting, recordkeeping, business conduct, disclosure, position limit, minimum net capital and registration requirements. Although the CFTC has released final rules under the Dodd-Frank Act, many of the provisions are subject to further final rulemaking, and thus the Dodd-Frank Act’s ultimate impact remains unclear.

The SEC proposed rules governing the use of derivatives by registered investment companies, which could affect the nature and extent of derivatives use by the Fund. The proposed rules have not yet been adopted and therefore the full impact of such rules is uncertain at this time. It is possible that such rules, if adopted, could limit the implementation of the Fund’s use of derivatives, which could have an adverse effect on the Fund.

Additionally, the Fund is operated by persons who have claimed an exclusion, granted to operators of registered investment companies like the Fund, from registration as a “commodity pool operator” under Rule 4.5 promulgated by the CFTC pursuant to its authority under the Commodity Exchange Act (the “CEA”) and, therefore, is not subject to registration or regulation as a “commodity pool operator.” As a result, the Fund is limited in its ability to use commodity futures (which include futures on broad-based securities indexes and interest rate futures) or options on commodity futures, engage in swaps transactions or make certain other investments (whether directly or indirectly through investments in other investment vehicles) for purposes other than bona fide hedging. With respect to transactions other than for bona fide hedging purposes, either: (1) the aggregate initial margin and premiums required to establish the Fund’s positions in such investments may not exceed 5% of the liquidation value of the Fund’s portfolio (after accounting for unrealized profits and unrealized losses on any such investments); or (2) the aggregate net notional value of such instruments, determined at the time the most recent position was established, may not exceed 100% of the liquidation value of the Fund’s portfolio (after accounting for unrealized profits and unrealized losses on any such positions). In addition to meeting one of the foregoing trading limitations, the Fund may not market itself as a commodity pool or otherwise as a vehicle for trading in the futures, options or swaps markets. If the Fund does not continue to claim the exclusion, it would likely become subject to registration and regulation as a commodity pool operator. The Fund may incur additional expenses as a result of the CFTC’s registration and regulatory requirements.

Anti-Takeover Provisions

The Fund’s Declaration of Trust and By-laws include provisions that could limit the ability of other entities or persons to acquire control of the Fund or convert the Fund to open-end status. These

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provisions could have the effect of depriving the Common Shareholders of opportunities to sell their Common Shares at a premium over the then-current market price of the Common Shares. See “Certain Provisions in the Declaration of Trust and By-Laws.”

Potential Conflicts of Interest Risk

Nuveen Fund Advisors and Nuveen Asset Management each provide a wide array of portfolio management and other asset management services to a mix of clients and may engage in ordinary course activities in which their respective interests or those of their clients may compete or conflict with those of the Fund. In certain circumstances, and subject to its fiduciary obligations under the Investment Advisers Act of 1940, Nuveen Asset Management may have to allocate a limited investment opportunity among its clients, which include closed-end funds, open-end funds and other commingled funds. Nuveen Fund Advisors and Nuveen Asset Management have each adopted policies and procedures designed to address such situations and other potential conflicts of interests.

For additional information about potential conflicts of interest, and the way in which Nuveen Fund Advisors and Nuveen Asset Management address such conflicts, please see “Subadviser—Nuveen Asset Management Conflict of Interest Policies” in the SAI.

The following risks are not considered to be principal risks of investing in the Fund:

Borrowing Risk

In addition to borrowing for leverage (see “Leverage”), the Fund may borrow for temporary or emergency purposes, to pay dividends, repurchase its shares, or clear portfolio transactions. Borrowing may exaggerate changes in the NAV of the Fund’s shares and may affect the Fund’s net income. When the Fund borrows money, it must pay interest and other fees, which will reduce the Fund’s returns if such costs exceed the returns on the portfolio securities purchased or retained with such borrowings. Any such borrowings are intended to be temporary. However, under certain market circumstances, such borrowings might be outstanding for longer periods of time.

Cybersecurity Risk

Technology, such as the internet, has become more prevalent in the course of business, and as such, the Fund and its service providers are susceptible to operational and information security risk resulting from cyber incidents. Cyber incidents refer to both intentional attacks and unintentional events including: processing errors, human errors, technical errors including computer glitches and system malfunctions, inadequate or failed internal or external processes, market-wide technical-related disruptions, unauthorized access to digital systems (through “hacking” or malicious software coding), computer viruses, and cyber-attacks which shut down, disable, slow or otherwise disrupt operations, business processes or website access or functionality (including denial of service attacks). Cyber incidents could adversely impact the Fund and cause the Fund to incur financial loss and expense, as well as face exposure to regulatory penalties, reputational damage, and additional compliance costs associated with corrective measures. Cyber incidents may cause the Fund or its service providers to lose proprietary information, suffer data corruption, lose operational capacity or fail to comply with applicable privacy and other laws. Among other potentially harmful effects, cyber incidents also may result in theft, unauthorized monitoring and failures in the physical infrastructure or operating systems that support the Fund and its service providers. In addition, substantial costs may be incurred in order

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to prevent any cyber incidents in the future. While the Fund’s service providers have established business continuity plans in the event of, and risk management systems to prevent, such cyber incidents, there are inherent limitations in such plans and systems including the possibility that certain risks have not been identified. Furthermore, the Fund cannot control the cybersecurity plans and systems put in place by its service providers or any other third parties whose operations may affect the Fund.

Certain Affiliations

Certain broker-dealers may be considered to be affiliated persons of the Fund, Nuveen Fund Advisors, Nuveen Asset Management, Nuveen and/or TIAA. Absent an exemption from the SEC or other regulatory relief, the Fund generally is precluded from effecting certain principal transactions with affiliated brokers, and its ability to purchase securities being underwritten by an affiliated broker or a syndicate including an affiliated broker, or to utilize affiliated brokers for agency transactions, is subject to restrictions. The Fund has not applied for and does not currently intend to apply for such relief. This could limit the Fund’s ability to engage in securities transactions and take advantage of market opportunities. In addition, unless and until the underwriting syndicate is broken in connection with the initial public offering of the Common Shares, the Fund will be precluded from effecting principal transactions with brokers who are members of the syndicate.

Unrated Securities Risk

The Fund may purchase securities that are not rated by any rating organization. Nuveen Asset Management may, after assessing such securities’ credit quality, internally assign ratings to certain of those securities in categories similar to those of rating organizations. Some unrated securities may not have an active trading market or may be difficult to value, which means the Fund might have difficulty selling them promptly at an acceptable price. To the extent that the Fund invests in unrated securities, the Fund’s ability to achieve its investment objective will be more dependent on Nuveen Asset Management’s credit analysis than would be the case when the Fund invests in rated securities.

Risks in Valuation

The Fund utilizes independent pricing services approved by the Board of Trustees to value portfolio instruments at their market value. If the pricing services are unable to provide a market value or if a significant event occurs such that the valuation(s) provided are deemed unreliable, the Fund may value portfolio instrument(s) at their fair value, which is generally the amount an owner might reasonably expect to receive upon a current sale. Valuation risks associated with investing in below investment grade debt instruments including, but not limited to: a limited number of market participants, a lack of publicly-available information, resale restrictions, settlement delays, corporate actions and adverse market conditions may make it difficult to value or sell such instruments. Because non-U.S. instruments may trade on days when Common Shares are not priced or traded, NAV can change at times when Common Shares cannot be sold.

Asset Segregation Risk

Certain portfolio management techniques, such as, among other things, using reverse repurchase agreements, purchasing securities on a when-issued or delayed delivery basis or entering into swap agreements, futures contracts or other derivative transactions, create leverage or its effect,

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and may be considered “senior securities’” (as that term is defined under the 1940 Act). To avoid having these instruments considered “senior securities,” the Fund may maintain liquid assets with its custodian in an amount with a value at least equal (on a daily market value basis or notional value basis, as applicable) to the aggregate amount of its obligations under these types of leveraging transactions (often referred to as “asset segregation”), enter into offsetting transactions, or otherwise “cover” certain transactions, in accordance with the 1940 Act, the rules thereunder, and applicable positions of the SEC and its staff. See “Portfolio Composition and Other Information—Asset Segregation” above. In the event that the Fund is unable to maintain sufficient assets, or otherwise “cover,” any open positions, a portion or all of these instruments will be classified as a “senior security” for 1940 Act purposes and be subject to certain limitations on “senior securities” under the 1940 Act. See “Leverage” above. The Fund may be restricted in its use of assets that are maintained for “asset segregation,” or committed as “cover,” for certain other purposes, which could result in the Fund earning a lower return on its portfolio than it might otherwise earn if it did not have to maintain those assets in respect of, or otherwise “cover,” such portfolio positions. To the extent the Fund’s assets are maintained or committed as “cover,” it could limit the Fund’s investment flexibility. Maintaining assets and covering positions will not limit or offset losses on the related leveraging positions.

Counterparty Risk

The Fund will be subject to credit risk with respect to the counterparties to the derivative transactions entered into by the Fund. Changes in the credit quality of the companies that serve as the Fund’s counterparties with respect to derivatives transactions may affect the value of those instruments. Because certain derivative transactions in which the Fund may engage may be traded between counterparties based on contractual relationships, the Fund is subject to the risk that a counterparty will not perform its obligations under the related contracts. If a counterparty becomes bankrupt or otherwise becomes unable to perform its obligations due to financial difficulties the Fund may sustain losses (including the full amount of its investment), may be unable to liquidate a derivatives position or may experience significant delays in obtaining any recovery in bankruptcy or other reorganization proceedings. By entering into derivatives transactions, the Fund assumes the risk that its counterparties could experience such financial hardships. Although the Fund intends to enter into transactions only with counterparties that Nuveen Fund Advisors believes to be creditworthy, there can be no assurance that a counterparty will not default and that the Fund will not sustain a loss on a transaction. In the event of a counterparty’s bankruptcy or insolvency, any collateral posted by the Fund in connection with a derivatives transaction may be subject to the conflicting claims of that counterparty’s creditors, and the Fund may be exposed to the risk of a court treating the Fund as a general unsecured creditor of the counterparty, rather than as the owner of the collateral.

The counterparty risk for cleared derivatives is generally lower than for uncleared OTC derivative transactions. In a cleared derivative transaction, generally, a clearing organization becomes substituted for each counterparty to a cleared derivative contract and each party to a trade looks only to the clearing organization for performance of financial obligations under the derivative contract. In effect, the clearing organization guarantees a party’s performance under the contract. However, there can be no assurance that a clearing organization, or its members, will satisfy its obligations to the Fund, or that the Fund would be able to recover the full amount of assets deposited on its behalf with the clearing organization in the event of the default by the clearing organization or the Fund’s clearing broker. In addition, cleared derivative transactions benefit from daily marking-to-market and settlement, and segregation and minimum capital requirements applicable to intermediaries. Uncleared

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OTC derivative transactions generally do not benefit from such protections. As a result, for uncleared OTC derivative transactions, there is the risk that a counterparty will not settle a transaction in accordance with its terms and conditions because of a dispute over the terms of the contract (whether or not bona fide) or because of a credit or liquidity problem, thus causing the Fund to suffer a loss. This risk is heightened for contracts with longer maturities where events may intervene to prevent settlement, or where the Fund has concentrated its transactions with a single or small group of counterparties.

Risks Related to the Fund’s Clearing Broker and Central Clearing Counterparty

The CEA requires swaps and futures clearing brokers registered as “futures commission merchants” to segregate all funds received from customers with respect to any orders for the purchase or sale of U.S. domestic futures contracts and cleared swaps from the brokers’ proprietary assets. Similarly, the CEA requires each futures commission merchant to hold in separate secure accounts all funds received from customers with respect to any orders for the purchase or sale of foreign futures contracts and cleared swaps and segregate any such funds from the funds received with respect to domestic futures contracts. However, all funds and other property received by a clearing broker from its customers are held by the clearing broker on a commingled basis in an omnibus account and may be invested in certain instruments permitted under applicable regulations. There is a risk that assets deposited by the Fund with any swaps or futures clearing broker as margin for futures contracts or cleared swaps may, in certain circumstances, be used to satisfy losses of other clients of the Fund’s clearing broker. In addition, the assets of the Fund might not be fully protected in the event of the Fund’s clearing broker’s bankruptcy, as the Fund would be limited to recovering only a pro rata share of all available funds segregated on behalf of the clearing broker’s customers for the relevant account class.

Similarly, the CEA requires a clearing organization approved by the CFTC as a derivatives clearing organization to segregate all funds and other property received from a clearing member’s clients in connection with domestic cleared derivative contracts from any funds held at the clearing organization to support the clearing member’s proprietary trading. Nevertheless, all customer funds held at a clearing organization in connection with any futures contracts are held in a commingled omnibus account and are not identified to the name of the clearing member’s individual customers. All customer funds held at a clearing organization with respect to cleared swaps of customers of a clearing broker are also held in an omnibus account, but CFTC rules require that the clearing broker notify the clearing organization of the amount of the initial margin provided by the clearing broker to the clearing organization that is attributable to each customer. With respect to futures and options contracts, a clearing organization may use assets of a non-defaulting customer held in an omnibus account at the clearing organization to satisfy payment obligations of a defaulting customer of the clearing member to the clearing organization. With respect to cleared swaps, a clearing organization generally cannot do so, but may do so if the clearing member does not provide accurate reporting to the clearing organization as to the attribution of margin among its clients. Also, since clearing brokers generally provide to clearing organizations the net amount of variation margin required for cleared swaps for all of its customers in the aggregate, rather than the gross amount of each customer, the Fund is subject to the risk that a clearing organization will not make variation margin payments owed to the Fund if another customer of the clearing member has suffered a loss and is in default. As a result, in the event of a default or the clearing broker’s other clients or the clearing broker’s failure to extend its own funds in connection with any such default, the Fund may not be able to recover the full amount of assets deposited by the clearing broker on behalf of the Fund with the clearing organization.

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Portfolio Turnover Risk

The Fund’s annual portfolio turnover rate may vary greatly from year to year, as well as within a given year. The portfolio turnover rate is not considered a limiting factor in the execution of investment decisions for the Fund. High portfolio turnover may result in the realization of net short-term capital gains by the Fund which, when distributed to Shareholders, will be taxable as ordinary income. In addition, a higher portfolio turnover rate results in correspondingly greater brokerage and other transactional expenses that are borne by the Fund.

Rating Agencies Risk

Rating agencies may fail to make timely changes in credit ratings and an issuer’s current financial condition may be better or worse than a rating indicates. In addition, rating agencies are subject to an inherent conflict of interest because they are often compensated by the same issuers whose securities they grade.

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FINANCIAL HIGHLIGHTS

The following Financial Highlights table is intended to help a prospective investor understand the Fund’s financial performance for the periods shown. Certain information reflects financial results for a single Common Share of the Fund. The total returns in the table represent the rate an investor would have earned or lost on an investment in Common Shares of the Fund (assuming reinvestment of all dividends). The Fund’s annual financial statements and financial highlights as of and for the fiscal years ended March 31, 2020, 2019, 2018, 2017, 2016 and 2015, including the financial highlights for the fiscal years then ended, have been audited by KPMG LLP (“KPMG”), an independent registered public accounting firm. KPMG has not reviewed or examined any records, transactions or events after the date of such reports. The information with respect to the fiscal periods ended prior to March 31, 2015 has been audited by other auditors. A copy of the Fund’s Annual Reports may be obtained from www.sec.gov or by visiting www.nuveen.com. The information contained in, or that can be accessed through, the Fund’s websites is not part of this prospectus, except to the extent specifically incorporated by reference in the SAI. Past results are not indicative of future performance.

The following per share data and ratios have been derived from information provided in the financial statements.

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Selected data for a Common Share outstanding throughout each period:

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THE FUND

The Fund is a diversified, closed-end management investment company registered under the 1940 Act. The Fund was organized as a Massachusetts business trust on December 4, 2009, pursuant to the Declaration of Trust, which is governed by the laws of the Commonwealth of Massachusetts. The Fund’s Common Shares are listed on the NYSE under the symbol “NBB.” The Fund’s principal office is located at 333 West Wacker Drive, Chicago, Illinois 60606, and its telephone number is (312) 917-7700.

USE OF PROCEEDS

Unless otherwise specified in a prospectus supplement, the Fund will use the net proceeds from any sales of Securities pursuant to this prospectus to make investments in accordance with the Fund’s investment objectives and policies or to redeem outstanding Preferred Shares.

To the extent a portion of the net proceeds from an offering are used to make investments, the relevant prospectus supplement will include an estimate of the length of time it is expected to take to invest such proceeds. The Fund anticipates that the net proceeds will be invested shortly following completion of the offering and in any event expects the time period to be less than three months. To the extent a portion of the net proceeds from an offering are used to redeem outstanding Preferred Shares, the Fund anticipates that such redemptions will be effected as soon as practicable after completion of the relevant offering.

Pending the use of proceeds, as described above, the Fund anticipates investing the proceeds in high-quality, short-term investments.

DESCRIPTION OF SECURITIES

The following is a brief description of the material terms of the Common Shares and the Preferred Shares of the Fund, except that the series designation, redemption terms, dividend rate or rates, and other details concerning any Preferred Shares issued under the registration statement of which this prospectus is a part will be disclosed in a prospectus supplement.

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The following provides information about the Fund’s outstanding Securities as of July 31, 2020:

Common Shares

The Declaration of Trust authorizes the issuance of an unlimited number of Common Shares. The Common Shares have a par value of $0.01 per share and, subject to the rights of holders of any Preferred Shares, have equal rights to the payment of dividends and the distribution of assets upon liquidation. The Common Shares when issued, are fully paid and, subject to matters discussed in “Certain Provisions in the Declaration of Trust and By-Laws,” non-assessable, and have no preemptive or conversion rights or rights to cumulative voting. A copy of the Declaration of Trust is filed with the SEC as an exhibit to the Fund’s registration statement of which this prospectus is a part. A copy may be obtained as described under “Where You Can Find More Information.”

Each whole Common Share has one vote with respect to matters upon which a shareholder vote is required, and each fractional share shall be entitled to a proportional fractional vote consistent with the requirements of the 1940 Act and the rules promulgated thereunder, and will vote together as a single class. Whenever the Fund incurs borrowings and/or Preferred Shares are outstanding, common shareholders will not be entitled to receive any cash distributions from the Fund unless all interest on such borrowings has been paid and all accumulated dividends on Preferred Shares have been paid, unless asset coverage (as defined in the 1940 Act) with respect to any borrowings would be at least 300% after giving effect to the distributions and asset coverage (as defined in the 1940 Act) with respect to Preferred Shares would be at least 200% after giving effect to the distributions. See “—Preferred Shares” below.

The Common Shares are listed on the NYSE and trade under the ticker symbol “NBB.” The Fund intends to hold annual meetings of shareholders so long as the Common Shares are listed on a national securities exchange and such meetings are required as a condition to such listing. The Fund will not issue share certificates.

Unlike open-end funds, closed-end funds like the Fund do not provide daily redemptions. Rather, if a shareholder determines to buy additional Common Shares or sell shares already held, the shareholder may conveniently do so by trading on the exchange through a broker or otherwise. Common shares of closed-end investment companies may frequently trade on an exchange at prices lower than NAV. Common shares of closed-end investment companies like the Fund have during some periods traded at prices higher than NAV and have during other periods traded at prices lower than NAV.

Because the market value of the Common Shares may be influenced by such factors as distribution levels (which are in turn affected by expenses), call protection, dividend stability, portfolio credit quality, NAV, relative demand for and supply of such shares in the market, general market and economic conditions, and other factors beyond the control of the Fund, the Fund cannot assure you that

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Common Shares will trade at a price equal to or higher than NAV in the future. The Common Shares are designed primarily for long-term investors, and investors in the Common Shares should not view the Fund as a vehicle for trading purposes. See “Repurchase of Fund Shares; Conversion to Open-End Fund.”

Preferred Shares

The Fund’s Declaration of Trust authorizes the issuance of an unlimited number of Preferred Shares in one or more classes or series, with rights as determined by the Board, by action of the Board without the approval of the common shareholders. In connection with the issuance of Preferred Shares, copies of the Declaration of Trust, and the applicable statement establishing and fixing the rights and preferences of Preferred Shares of the applicable series, and, if applicable, the related supplement, will be filed with the SEC as exhibits to the registration statement. Copies may be obtained as described under “Where You Can Find More Information.”

Ranking and Priority of Payment

Each Preferred Share will rank on parity with each other and other Preferred Shares with respect to the payment of dividends and the distribution of assets upon liquidation. Each Preferred Share will rank senior in priority to the Common Shares as to the payment of dividends and as to the distribution of assets upon dissolution, liquidation or winding up of the affairs of the Fund.

Dividends and Distributions

The holders of Preferred Shares of each series are entitled to receive, when, as and if declared by the Board, out of funds legally available therefor in accordance with the Declaration of Trust and applicable law, cumulative cash dividends at the dividend rate for the Preferred Shares of such series payable on the dividend payment dates with respect to the Preferred Shares of such series. Holders of Preferred Shares are not entitled to any dividend, whether payable in cash, property or shares, in excess of full cumulative dividends on the Preferred Shares. No interest, or sum of money in lieu of interest, shall be payable in respect of any dividend payment or payments on Preferred Shares which may be in arrears, and no additional sum of money will be payable in respect of such arrearage.

Voting Rights

Preferred Shares are required to be voting shares and to have equal voting rights with Common Shares. Except as otherwise indicated in this prospectus, the applicable prospectus supplement or the SAI and except as otherwise required by applicable law, Preferred Shares would vote together with the holders of Common Shares as a single class.

Holders of Preferred Shares, voting as a separate class, will be entitled to elect two of the Fund’s trustees. The remaining trustees will be elected by the holders of Common Shares and the holders of Preferred Shares, voting together as a single class. In the unlikely event that two full years of accumulated dividends are unpaid on the Preferred Shares, the holders of all outstanding Preferred Shares, voting as a separate class, will be entitled to elect a majority of the Fund’s trustees until all dividends in arrears have been paid or declared and set apart for payment. In order for the Fund to take certain actions or enter into certain transactions, a separate class vote of holders of Preferred Shares would be required, in addition to the single class vote of the holders of Preferred Shares and Common Shares. See “Certain Provisions in the Declaration of Trust and By-Laws.”

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Redemption, Purchase and Sale of Preferred Shares

The terms of the Preferred Shares of any series may provide that they may be subject to optional or mandatory redemption by the Fund at certain times or under certain circumstances, in whole or in part, at the liquidation preference per share plus accumulated dividends. The terms for optional redemption of Preferred Shares may provide for the payment of a redemption premium, which will be described in the applicable prospectus supplement. Any redemption or purchase of Preferred Shares by the Fund will reduce the leverage applicable to Common Shares, while any issuance of Preferred Shares by the Fund would increase such leverage.

Ratings and Asset Coverage

To the extent Preferred Shares are outstanding, the composition of the Fund’s portfolio will reflect guidelines established by the NRSRO or NRSROs rating such shares. These guidelines may impose requirements different from or in addition to those required under the 1940 Act, and generally include asset coverage requirements, portfolio characteristics such as portfolio diversification and credit rating criteria, and qualitative views on the Fund and Fund management. Although the Fund’s failure to meet such requirements or criteria under applicable guidelines may cause the Fund to sell portfolio positions or to redeem Preferred Shares at inopportune times in an amount necessary to restore compliance with the guidelines, or may result in a downgrade of ratings, the Fund currently does not anticipate that these restrictions or guidelines will impede the management of the Fund’s portfolio in accordance with the Fund’s investment objectives and policies.

There can be no assurance that one or more NRSROs will not alter its or their rating criteria resulting in downgrades of ratings, that the Fund will maintain any ratings of the Preferred Shares, or, if at any time the Preferred Shares have one or more ratings, that any particular ratings will be maintained. The Fund may, at any time, replace a NRSRO with another NRSRO or terminate the services of any NRSROs then providing a rating for Preferred Shares without replacement, in either case, without the approval of shareholders of the Fund (except as may be otherwise specifically provided for a series of Preferred Shares). In addition, the NRSRO guidelines adopted by the Fund in connection with a NRSRO’s rating of Preferred Shares may be changed or eliminated at any time without the approval of shareholders of the Fund, including in connection with the change or elimination of any or all long-term ratings of the Preferred Shares.

Ratings of the Preferred Shares neither eliminate nor mitigate the risks of investing in Common Shares or Preferred Shares. See “Risk Factors” above and in the applicable prospectus supplement.

THE FUND’S INVESTMENTS

Investment Objectives and Policies

The Fund’s primary investment objective is to provide current income through investments in taxable municipal securities. As a secondary objective, the Fund seeks to enhance portfolio value and total return.

The Fund seeks to achieve its investment objectives by investing primarily in a diversified portfolio of taxable municipal securities. Under normal circumstances, the Fund will invest at least 80% of its Assets in taxable municipal securities. The Fund may invest up to 20% of its Assets in

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securities other than taxable municipal securities, including municipal securities the interest income from which is exempt from regular federal income tax (sometimes referred to as “tax-exempt municipal securities”), U.S. Treasury securities and obligations of the U.S. Government, its agencies and instrumentalities. The Fund may purchase taxable municipal securities (including for purposes of the 80% test) and other tax-exempt municipal securities in the form of bonds, notes, leases or certificates of participation; structured as callable or non-callable; with payment forms that include fixed-coupon, variable rate, zero coupon, capital appreciation bonds, floating rate securities, inverse floating rate securities and other derivative instruments that replicate investment exposure to taxable municipal securities or other municipal securities. Such municipal securities may be acquired through investments in pooled vehicles, partnerships or other investment companies. The Fund may also purchase municipal securities representing a wide range of sectors and purposes.

Under normal circumstances, the Fund will invest at least 80% of its Managed Assets in securities that at the time of investment are investment grade quality. A security is considered investment grade quality if it is rated within the four highest letter grades (BBB or Baa or better) by at least one of the nationally recognized statistical rating organizations (“NRSROs”) that rate such security (even if it is rated lower by another), or if it is unrated by any NRSRO but judged to be of comparable quality by Nuveen Asset Management. Under normal circumstances, the Fund may invest up to 20% of its Managed Assets in securities rated below investment grade or are unrated by any NRSRO but judged to be of comparable quality by Nuveen Asset Management.

Securities of below-investment-grade quality (Ba/BB or below) are commonly referred to as “junk bonds.” Municipal securities rated below-investment-grade quality are obligations of issuers that are considered predominantly speculative with respect to the issuer’s capacity to pay interest and repay principal according to the terms of the obligation and, therefore, carry greater investment risk, including the possibility of issuer default and bankruptcy and increased market price volatility. Municipal securities rated below-investment-grade tend to be less marketable than higher-quality securities because the market for them is less broad. The market for unrated municipal securities is even narrower. During periods of thin trading in these markets, the spread between bid and asked prices is likely to increase significantly and the Fund may have greater difficulty selling its holdings of these types of portfolio securities. The Fund will be more dependent on the Adviser’s and/or the Sub-Adviser’s research and analysis when investing in these securities.

Municipal securities rated Baa or BBB are considered “investment grade” securities. Issuers of municipal securities rated BBB or Baa are regarded as having average creditworthiness relative to other U.S. municipal issuers; however, adverse economic conditions or changing circumstances are more likely to lead to a weakened capacity of the issuer to meet its financial commitments.

The foregoing credit quality policy targets apply only at the time a security is purchased, and the Fund is not required to dispose of a security in the event that a rating agency upgrades or downgrades its assessment of the credit characteristics of a particular issuer or that valuation changes of various municipal securities cause the Fund’s portfolio to fail to satisfy those targets. In determining whether to retain or sell such a security, the Adviser and/or the Sub-Adviser may consider such factors as the Adviser’s and/or the Sub-Adviser’s assessment of the credit quality of the issuer of such security, the price at which such security could be sold and the rating, if any, assigned to such security by other rating agencies. The credit ratings assigned by rating agencies from time to time, represent their opinions as to the quality of the municipal securities they rate. However, it should be emphasized that ratings are general and are not absolute standards of quality. Consequently, municipal securities with

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the same maturity, coupon and rating may have different yields while obligations of the same maturity and coupon with different ratings may have the same yield. A general description of the ratings of municipal securities by S&P, Moody’s and Fitch is set forth in [Appendix A].

The Fund will generally invest in securities with intermediate- or long-term maturities. The Fund anticipates having a weighted average maturity of 15 to 35 years. The weighted average maturity of securities held by the Fund may be shortened or lengthened, depending on market conditions and on an assessment by the Fund’s portfolio manager of which segments of the securities market offer the most favorable relative investment values and opportunities for income and total return. As of [-], 2020, the average effective maturity of the portfolio of the Fund was [-] years.

In addition, under normal circumstances, the Fund:

During temporary defensive periods or in order to keep cash fully invested, the Fund may deviate from its investment policies and objectives. During such periods, the Fund may invest up to 100% of its Managed Assets in short-term investments, including high quality, short-term securities that may be either tax-exempt or taxable, or may invest in short-, intermediate-, or long-term U.S. Treasury Bonds. There can be no assurance that such strategies will be successful.

The Fund may purchase municipal securities that are additionally secured by insurance, bank credit agreements or escrow accounts. The credit quality of companies which provide such credit enhancements may affect the value of those securities. Although the insurance feature may reduce certain financial risks, the premiums for insurance and the higher market price paid for insured obligations may reduce the Fund’s income. The insurance feature guarantees only the payment of principal and interest on the obligation when due and does not guarantee the market value of the insured obligations, which will fluctuate with the bond market and the financial success of the issuer and the insurer, and the effectiveness and value of the insurance itself is dependent on the continued creditworthiness of the insurer. No representation is made as to the insurers’ ability to meet their commitments.

Obligations of issuers of municipal securities are subject to the provisions of bankruptcy, insolvency and other laws affecting the rights and remedies of creditors, such as the Bankruptcy Reform Act of 1978. In addition, the obligations of such issuers may become subject to the laws enacted in the future by Congress, state legislatures or referenda extending the time for payment of principal or interest, or both, or imposing other constraints upon enforcement of such obligations or

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upon municipalities to levy taxes. There is also the possibility that, as a result of legislation or other conditions, the power or ability of any issuer to pay, when due, the principal of and interest on its municipal securities may be materially affected.

The Fund is diversified for purposes of the 1940 Act. Consequently, as to 75% of its assets, the Fund may not invest more than 5% of its total assets in the securities of any single issuer (and in not more than 10% of the outstanding voting securities of an issuer), except that this limitation does not apply to cash, securities of the U.S. government, its agencies and instrumentalities, and securities of other investment companies.

“Assets” means net assets of the Fund plus the amount of any borrowings for investment purposes. “Managed Assets” means the total assets of the Fund, minus the sum of its accrued liabilities (other than Fund liabilities incurred for the express purpose of creating leverage). Total assets for this purpose shall include assets attributable to the Fund’s use of leverage (whether or not those assets are reflected in the Fund’s financial statements for purposes of generally accepted accounting principles), and derivatives will be valued at their market value.

Except for the Fund’s investment objectives, which are fundamental policies of the Fund, each of the foregoing investment policies is a non-fundamental investment policy that can be changed by the Fund’s Board without a shareholder vote. However, the Fund’s investment policy to invest at least 80% of its Assets in taxable municipal securities may be changed by the Board only following the provision of 60 days’ prior notice to shareholders. The Fund can only change its fundamental investment restrictions with the approval of the holders of a “majority of the outstanding voting securities” of the Fund as is defined in the 1940 Act. When used with respect to particular shares of the Fund, a “majority of the outstanding voting securities” means the vote of (i) 67% or more of the Fund’s shares present at a meeting, if the holders of more than 50% of the Fund’s shares are present or represented by proxy; or (ii) more than 50% of the Fund’s outstanding common shares, whichever is less.

Integrated Leverage and Hedging Strategy

The Fund employs an integrated leverage and hedging strategy to seek to enhance its potential current income and longer-term risk-adjusted total return, while seeking to maintain a level of interest rate risk comparable to that of the Bloomberg Barclays Taxable Municipal Long Bond Index (the “Index”). The Fund uses leverage instruments that will have a funding cost based on short- to intermediate-term market interest rates. Because such interest rates are expected to be generally lower than the yields on the long-term bonds in which a Fund invests, Nuveen Asset Management believes that the use of leverage will generally increase common share net income.

The use of leverage involves increased risk, including increased variability of the Fund’s net income, distributions and/or net asset value in relation to market changes. In particular, leverage increases interest rate risk, which is the risk that the prices of portfolio securities will fall (or rise) if market interest rates for those securities rise (or fall). The Fund’s hedging strategy seeks to reduce this increased interest rate risk by systematically reducing the leverage-adjusted portfolio duration (duration is a measure of the sensitivity of bond prices to changes in interest rates) to a level comparable to the duration of the Index. This hedging strategy is not expected to reduce other types of risk, such as credit risk, which are also increased by the Fund’s use of leverage. The Fund’s leverage

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and hedging techniques are referred to as integrated because the Fund’s use of hedging strategies is expected to be directly calibrated to any increased interest rate risk, relative to the Fund’s benchmark, due to the use of leverage.

The Fund’s use of derivatives such as bond futures or interest rate swaps in hedging interest rate risk will generate costs that will effectively reduce the Fund’s net asset value. These capital costs may be offset over time by capital appreciation of a Fund’s portfolio. The potential to achieve such capital appreciation will depend largely on Nuveen Asset Management’s investment capabilities in executing the Fund’s investment strategy as well as the performance of BABs relative to the securities underlying the Fund’s hedging instruments. If and to the extent that such capital appreciation does not occur or is less than these hedging costs, however, the Fund’s total returns can be expected to be less than its net earnings (and, over time, distributions).

Portfolio Composition

The Fund’s portfolio will be composed principally of the following investments.

Municipal Securities

General. The Fund may invest in taxable municipal securities (including BABs) and tax-exempt municipal securities, including municipal bonds and notes, other securities issued to finance and refinance public projects, and other related securities and derivative instruments creating exposure to municipal bonds, notes and securities that provide for the payment of interest income that is exempt from regular U.S. federal income tax. Municipal securities are often issued by state and local governmental entities to finance or refinance public projects such as roads, schools, and water supply systems. Municipal securities may also be issued on behalf of private entities or for private activities, such as housing, medical and educational facility construction, or for privately owned transportation, electric utility or pollution control projects. Municipal securities may be issued on a long term basis to provide permanent financing. The repayment of such debt may be secured generally by a pledge of the full faith and credit taxing power of the issuer, a limited or special tax, or any other revenue source, including project revenues, which may include tolls, fees and other user charges, lease payments and mortgage payments. Municipal securities may also be issued to finance projects on a short-term interim basis, anticipating repayment with the proceeds of the later issuance of long-term debt. The Fund may purchase municipal securities in the form of bonds, notes, leases or certificates of participation; structured as callable or non-callable; with payment forms including fixed coupon, variable rate or zero coupon, including capital appreciation bonds, floating rate securities, and inverse floating rate securities; or may be acquired through investments in pooled vehicles, partnerships or other investment companies. Inverse floating rate securities are securities that pay interest at rates that vary inversely with changes in prevailing short-term tax-exempt interest rates and represent a leveraged investment in an underlying municipal security, which could have the economic effect of leverage.

Municipal securities are either general obligation or revenue bonds and typically are issued to finance public projects (such as roads or public buildings), to pay general operating expenses or to refinance outstanding debt. General obligation bonds are backed by the full faith and credit, or taxing authority, of the issuer and may be repaid from any revenue source; revenue bonds may be repaid only from the revenues of a specific facility or source. The Fund also may purchase municipal securities that represent lease obligations, municipal notes, pre-refunded municipal bonds, private activity bonds, floating rate securities and other related securities and may purchase derivative instruments that create exposure to municipal bonds, notes and securities.

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The yields on municipal securities depend on a variety of factors, including prevailing interest rates and the condition of the general money market and the municipal bond market, the size of a particular offering, the maturity of the obligation and the rating of the issue. A municipal security’s market value generally will depend upon its form, maturity, call features, and interest rate, as well as the credit quality of the issuer, all such factors examined in the context of the municipal securities market and interest rate levels and trends. The market value of municipal securities will vary with changes in interest rate levels and as a result of changing evaluations of the ability of their issuers to meet interest and principal payments.

BABs offered an alternative form of financing for state and local government entities whose primary means for accessing the capital markets traditionally had been through issuance of tax-exempt municipal securities. BABs are taxable municipal obligations issued pursuant to the American Recovery and Reinvestment Act of 2009. Enacted in February 2009 with the intent to assist state and local governments in financing capital projects at lower borrowing costs, the American Recovery and Reinvestment Act of 2009 authorized state and local governments to issue taxable bonds on which, assuming certain specified conditions are satisfied, issuers may either (i) receive payments from the U.S. Treasury equal to a specified percentage of their interest payments (in the case of direct pay BABs) or (ii) cause investors in the bonds to receive federal tax credits (in the case of tax credit BABs). Unlike most other municipal obligations, interest received on BABs is subject to U.S. federal income tax and may be subject to state income tax. Under the terms of the American Recovery and Reinvestment Act of 2009, issuers of direct pay BABs are entitled to receive payments from the U.S. Treasury currently equal to 35% (or 45% in the case of Recovery Zone Economic Development Bonds) of the interest paid on the bonds. Holders of tax credit BABs receive a federal tax credit currently equal to 35% of the coupon interest received. The Fund does not expect to receive (or pass through to common shareholders) tax credits as a result of its investments. The federal interest subsidy or tax credit continues for the life of the bonds, provided that the issuer continues to meet all applicable program eligibility requirements. Under the sequestration process under the Budget Control Act of 2011, automatic spending cuts that became effective on March 1, 2013 reduced the federal subsidy for BABs and other subsidized taxable municipal bonds. The reduced federal subsidy has been extended through 2024. The subsidy payments were reduced by 6.6% in 2018 and 6.2% in 2019. The Fund cannot predict future reductions in the federal subsidy for BABs and other subsidized taxable municipal bonds.

Pursuant to the terms of the American Recovery and Reinvestment Act of 2009, the issuance of Build America Bonds ceased on December 31, 2010. As a result, the availability of such bonds is limited and there can be no assurance that Build America Bonds will be actively traded. The market for the bonds and/or their liquidity may be negatively affected. No further issuance is permitted unless Congress were to renew the program at a future date.

Municipal Leases and Certificates of Participation. The Fund also may purchase municipal securities that represent lease obligations and certificates of participation in such leases. These carry special risks because the issuer of the securities may not be obligated to appropriate money annually to make payments under the lease. A municipal lease is an obligation in the form of a lease or installment purchase that is issued by a state or local government to acquire equipment and facilities. Income from such obligations generally is exempt from state and local taxes in the state of issuance. Leases and installment purchase or conditional sale contracts (which normally provide for title to the leased asset to pass eventually to the governmental issuer) have evolved as a means for governmental issuers to acquire property and equipment without meeting the constitutional and statutory requirements for the

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issuance of debt. The debt issuance limitations are deemed to be inapplicable because of the inclusion in many leases or contracts of “non-appropriation” clauses that relieve the governmental issuer of any obligation to make future payments under the lease or contract unless money is appropriated for such purpose by the appropriate legislative body on a yearly or other periodic basis. In addition, such leases or contracts may be subject to the temporary abatement of payments in the event the issuer is prevented from maintaining occupancy of the leased premises or utilizing the leased equipment or facilities. Although the obligations may be secured by the leased equipment or facilities, the disposition of the property in the event of non-appropriation or foreclosure might prove difficult, time consuming and costly, and result in a delay in recovering, or the failure to recover fully, the Fund’s original investment. To the extent that the Fund invests in unrated municipal leases or participates in such leases, the credit quality rating and risk of cancellation of such unrated leases will be monitored on an ongoing basis. In order to reduce this risk, the Fund will purchase municipal securities representing lease obligations only where the Adviser and/or the Sub-Adviser believes the issuer has a strong incentive to continue making appropriations until maturity.

A certificate of participation represents an undivided interest in an unmanaged pool of municipal leases, an installment purchase agreement or other instruments. The certificates typically are issued by a municipal agency, a trust or other entity that has received an assignment of the payments to be made by the state or political subdivision under such leases or installment purchase agreements. Such certificates provide the Fund with the right to a pro rata undivided interest in the underlying municipal securities. In addition, such participations generally provide the Fund with the right to demand payment, on not more than seven days’ notice, of all or any part of the Fund’s participation interest in the underlying municipal securities, plus accrued interest.

Municipal Notes. Municipal securities in the form of notes generally are used to provide for short-term capital needs, in anticipation of an issuer’s receipt of other revenues or financing, and typically have maturities of up to three years. Such instruments may include tax anticipation notes, revenue anticipation notes, bond anticipation notes, tax and revenue anticipation notes and construction loan notes. Tax anticipation notes are issued to finance the working capital needs of governments. Generally, they are issued in anticipation of various tax revenues, such as income, sales, property, use and business taxes, and are payable from these specific future taxes. Revenue anticipation notes are issued in expectation of receipt of other kinds of revenue, such as federal revenues available under federal revenue sharing programs. Bond anticipation notes are issued to provide interim financing until long-term bond financing can be arranged. In most cases, the long-term bonds then provide the funds needed for repayment of the bond anticipation notes. Tax and revenue anticipation notes combine the funding sources of both tax anticipation notes and revenue anticipation notes. Construction loan notes are sold to provide construction financing. Mortgage notes insured by the Federal Housing Administration secure these notes; however, the proceeds from the insurance may be less than the economic equivalent of the payment of principal and interest on the mortgage note if there has been a default. The anticipated revenues from taxes, grants or bond financing generally secure the obligations of an issuer of municipal notes. However, an investment in such instruments presents a risk that the anticipated revenues will not be received or that such revenues will be insufficient to satisfy the issuer’s payment obligations under the notes or that refinancing will be otherwise unavailable.

Pre-Refunded Municipal Securities. The principal of, and interest on, pre-refunded municipal securities are no longer paid from the original revenue source for the securities. Instead, the source of such payments is typically an escrow fund consisting of U.S. Government securities. The assets in the escrow fund are derived from the proceeds of refunding bonds issued by the same issuer as the

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pre-refunded municipal securities. Issuers of municipal securities use this advance refunding technique to obtain more favorable terms with respect to securities that are not yet subject to call or redemption by the issuer. For example, advance refunding enables an issuer to refinance debt at lower market interest rates, restructure debt to improve cash flow or eliminate restrictive covenants in the indenture or other governing instrument for the pre-refunded municipal securities. However, except for a change in the revenue source from which principal and interest payments are made, the pre-refunded municipal securities remain outstanding on their original terms until they mature or are redeemed by the issuer.

Private Activity Bonds. Private activity bonds are issued by or on behalf of public authorities to obtain funds to provide privately operated housing facilities, airport, mass transit or port facilities, sewage disposal, solid waste disposal or hazardous waste treatment or disposal facilities and certain local facilities for water supply, gas or electricity. Other types of private activity bonds, the proceeds of which are used for the construction, equipment, repair or improvement of privately operated industrial or commercial facilities, may constitute municipal securities, although the current federal tax laws place substantial limitations on the size of such issues.

Inverse Floating Rate Securities. The Fund may invest in inverse floating rate securities. Inverse floating rate securities are securities whose interest rates bear an inverse relationship to the interest rate on another security or the value of an index. Generally, inverse floating rate securities represent beneficial interests in a special purpose trust, commonly referred to as a “tender option bond trust” (“TOB trust”), that holds municipal bonds. The TOB trust typically sells two classes of beneficial interests or securities: floating rate securities (sometimes referred to as short-term floaters or tender option bonds (“TOBs”)), and inverse floating rate securities (sometimes referred to as inverse floaters). Both classes of beneficial interests are represented by certificates or receipts. The floating rate securities have first priority on the cash flow from the municipal bonds held by the TOB trust. In this structure, the floating rate security holders have the option, at periodic short-term intervals, to tender their securities to the trust for purchase and to receive the face value thereof plus accrued interest. The obligation of the trust to repurchase tendered securities is supported by a remarketing agent and by a liquidity provider. As consideration for providing this support, the remarketing agent and the liquidity provider receive periodic fees. The holder of the short-term floater effectively holds a demand obligation that bears interest at the prevailing short-term, tax-exempt rate. However, the trust is not obligated to purchase tendered short-term floaters in the event of certain defaults with respect to the underlying municipal bonds or a significant downgrade in the credit rating assigned to the bond issuer.

As the holder of an inverse floating rate investment, the Fund receives the residual cash flow from the TOB trust. Because the holder of the short-term floater is generally assured liquidity at the face value of the security plus accrued interest, the holder of the inverse floater assumes the interest rate cash flow risk and the market value risk associated with the municipal bond deposited into the TOB trust. The volatility of the interest cash flow and the residual market value will vary with the degree to which the trust is leveraged. This is expressed in the ratio of the total face value of the short-term floaters to the value of the inverse floaters that are issued by the TOB trust, and can exceed three times for more “highly leveraged” trusts. All voting rights and decisions to be made with respect to any other rights relating to the municipal bonds held in the TOB trust are passed through, pro rata, to the holders of the short-term floaters and to the Fund as the holder of the associated inverse floaters.

Because any increases in the interest rate on the short-term floaters issued by a TOB trust would reduce the residual interest paid on the associated inverse floaters, and because fluctuations in the value

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of the municipal bond deposited in the TOB trust would affect only the value of the inverse floater and not the value of the short-term floater issued by the trust so long as the value of the municipal bond held by the trust exceeded the face amount of short-term floaters outstanding, the value of inverse floaters is generally more volatile than that of an otherwise comparable municipal bond held on an unleveraged basis outside a TOB trust. Inverse floaters generally will underperform the market of fixed-rate bonds in a rising interest rate environment (i.e., when bond values are falling), but will tend to outperform the market of fixed-rate bonds when interest rates decline or remain relatively stable. Although volatile in value and return, inverse floaters typically offer the potential for yields higher than those available on fixed-rate bonds with comparable credit quality, coupon, call provisions and maturity. Inverse floaters have varying degrees of liquidity or illiquidity based primarily upon the inverse floater holder’s ability to sell the underlying bonds deposited in the TOB trust at an attractive price.

The Fund may invest in inverse floating rate securities issued by TOB trusts in which the liquidity providers have recourse to the Fund pursuant to a separate shortfall and forbearance agreement. Such an agreement would require the Fund to reimburse the liquidity provider, among other circumstances, upon termination of the TOB trust for the difference between the liquidation value of the bonds held in the trust and the principal amount and accrued interest due to the holders of floating rate securities issued by the trust. The Fund will enter into such a recourse agreement (1) when the liquidity provider requires such a recourse agreement because the level of leverage in the TOB trust exceeds the level that the liquidity provider is willing to support absent such an agreement; and/or (2) to seek to prevent the liquidity provider from collapsing the trust in the event the municipal bond held in the trust has declined in value to the point where it may cease to exceed the face amount of outstanding short-term floaters. In an instance where the Fund has entered such a recourse agreement, the Fund may suffer a loss that exceeds the amount of its original investment in the inverse floating rate securities; such loss could be as great as that original investment amount plus the face amount of the floating rate securities issued by the trust plus accrued interest thereon.

The Fund will segregate or earmark liquid assets with its custodian in accordance with the 1940 Act to cover its obligations with respect to its investments in TOB trusts.

The Fund may invest in both inverse floating rate securities and floating rate securities (as discussed below) issued by the same TOB trust.

Floating Rate Securities. The Fund also may invest in short-term floating rate securities, as described above, issued by TOB trusts. Generally, the interest rate earned will be based upon the market rates for municipal securities with maturities or remarketing provisions that are comparable in duration to the periodic interval of the tender option, which may vary from weekly, to monthly, to other periods of up to one year. Since the tender option feature provides a shorter term than the final maturity or first call date of the underlying municipal bond deposited in the trust, the Fund, as the holder of the floating rate securities, relies upon the terms of the remarketing and liquidity agreements with the financial institution that acts as remarketing agent and/or liquidity provider as well as the credit strength of that institution. As further assurance of liquidity, the terms of the TOB trust provide for a liquidation of the municipal bond deposited in the trust and the application of the proceeds to pay off the floating rate securities. The TOB trusts that are organized to issue both short-term floating rate securities and inverse floaters generally include liquidation triggers to protect the investor in the floating rate securities.

Special Taxing Districts. Special taxing districts are organized to plan and finance infrastructure developments to induce residential, commercial and industrial growth and

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redevelopment. The bond financing methods such as tax increment finance, tax assessment, special services district and Mello-Roos bonds, generally are payable solely from taxes or other revenues attributable to the specific projects financed by the bonds without recourse to the credit or taxing power of related or overlapping municipalities. They often are exposed to real estate development-related risks and can have more taxpayer concentration risk than general tax-supported bonds, such as general obligation bonds. Further, the fees, special taxes, or tax allocations and other revenues that are established to secure such financings generally are limited as to the rate or amount that may be levied or assessed and are not subject to increase pursuant to rate covenants or municipal or corporate guarantees. The bonds could default if development failed to progress as anticipated or if larger taxpayers failed to pay the assessments, fees and taxes as provided in the financing plans of the districts.

Illiquid Securities

The Fund may invest in municipal securities and other instruments that, at the time of investment, are illiquid (i.e., securities that are not readily marketable). For this purpose, illiquid securities may include, but are not limited to, restricted securities (securities the disposition of which is restricted under the federal securities laws), securities that may only be resold pursuant to Rule 144A under the Securities Act, that are deemed to be illiquid, and certain repurchase agreements. Inverse floating rate securities or the residual interest certificates of tender option bond trusts are not considered illiquid securities. The Board or its delegate has the ultimate authority to determine which securities are liquid or illiquid. The Board has delegated to Nuveen Asset Management the day-to-day determination of the illiquidity of any security held by the Fund, although it has retained oversight and ultimate responsibility for such determinations. Currently, no definitive liquidity criteria are used. Each Board has directed Nuveen Asset Management, when making liquidity determinations, to consider such factors as (i) the nature of the market for a security (including the institutional private resale market; the frequency of trades and quotes for the security; the number of dealers willing to purchase or sell the security; the amount of time normally needed to dispose of the security; and the method of soliciting offers and the mechanics of transfer), (ii) the terms of certain securities or other instruments allowing for the disposition to a third party or the issuer thereof (e.g., certain repurchase obligations and demand instruments), and (iii) other relevant factors. The assets used to cover OTC derivatives held by the Fund will be considered illiquid until the OTC derivatives are sold to qualified dealers who agree that the Fund may repurchase them at a maximum price to be calculated by a formula set forth in an agreement. The “cover” for an OTC derivative subject to this procedure would be considered illiquid only to the extent that the maximum repurchase price under the formula exceeds the intrinsic value of the derivative.

Restricted securities may be sold only in privately negotiated transactions or in a public offering with respect to which a registration statement is in effect under the Securities Act. Where registration is required, the Fund may be obligated to pay all or part of the registration expenses and a considerable period may elapse between the time of the decision to sell and the time the Fund may be permitted to sell a security under an effective registration statement. If, during such a period, adverse market conditions were to develop, the Fund might obtain a less favorable price than that which prevailed when it decided to sell. Illiquid securities will be priced at a fair value as determined in good faith by the Board or its delegatee. If, through the appreciation of illiquid securities or the depreciation of liquid securities, the Fund should be in a position where more than 50% of the value of its Managed Assets is invested in illiquid securities, including restricted securities that are not readily marketable, the Fund will take such steps as are deemed advisable by Nuveen Asset Management, if any, to protect liquidity.

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When-Issued and Delayed-Delivery Transactions

The Fund may buy and sell municipal securities on a when-issued or delayed delivery basis, making payment or taking delivery at a later date, normally within 15 to 45 days of the trade date. On such transactions, the payment obligation and the interest rate are fixed at the time the buyer enters into the commitment. Beginning on the date the Fund enters into a commitment to purchase securities on a when-issued or delayed delivery basis, the Fund is required under interpretations of the SEC to segregate liquid assets, consisting of cash, cash equivalents or liquid securities having a market value, at all times, at least equal to the amount of the commitment. Income generated by any such assets which provide taxable income for federal income tax purposes is includable in the taxable income of the Fund and, to the extent distributed, will be taxable to shareholders. The Fund may enter into contracts to purchase municipal securities on a forward basis (i.e., where settlement will occur more than 60 days from the date of the transaction) only to the extent that the Fund specifically collateralizes such obligations with a security that is expected to be called or mature within 60 days before or after the settlement date of the forward transaction. The commitment to purchase securities on a when-issued, delayed delivery or forward basis may involve an element of risk because no interest accrues on the bonds prior to settlement and, at the time of delivery, the market value may be less than cost.

Derivatives

General. The Fund may invest in certain derivative instruments in pursuit of its investment objectives. Such instruments include financial futures contracts, swap contracts (including interest rate and credit default swaps), options on financial futures, options on swap contracts or other derivative instruments. Credit default swaps may require initial premium (discount) payments as well as periodic payments (receipts) related to the interest leg of the swap or to the default of a reference obligation. If the Fund is a seller of a contract, the Fund would be required to pay the par (or other agreed upon) value of a referenced debt obligation to the counterparty in the event of a default or other credit event by the reference issuer, such as a U.S. or foreign corporate issuer, with respect to such debt obligations. In return, the Fund would receive from the counterparty a periodic stream of payments over the term of the contract provided that no event of default has occurred. If no default occurs, the Fund would keep the stream of payments and would have no payment obligations. As the seller, the Fund would be subject to investment exposure on the notional amount of the swap. If the Fund is a buyer of a contract, the Fund would have the right to deliver a referenced debt obligation and receive the par (or other agreed-upon) value of such debt obligation from the counterparty in the event of a default or other credit event (such as a credit downgrade) by the reference issuer, such as a U.S. or foreign corporation, with respect to its debt obligations. In return, the Fund would pay the counterparty a periodic stream of payments over the term of the contract provided that no event of default has occurred. If no default occurs, the counterparty would keep the stream of payments and would have no further obligations to the Fund. Interest rate swaps involve the exchange by the Fund with a counterparty of their respective commitments to pay or receive interest, such as an exchange of fixed-rate payments for floating rate payments. The Fund will usually enter into interest rate swaps on a net basis; that is, the two payment streams will be netted out in a cash settlement on the payment date or dates specified in the instrument, with the Fund receiving or paying, as the case may be, only the net amount of the two payments.

The Adviser and/or the Sub-Adviser may use derivative instruments to seek to enhance return, to hedge some of the risk of the Fund’s investments in municipal securities or as a substitute for a position in the underlying asset.

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There is no assurance that these derivative strategies will be available at any time or that the Adviser and/or the Sub-Adviser will determine to use them for the Fund or, if used, that the strategies will be successful.

Limitations on the Use of Futures, Options on Futures and Swaps. The Adviser has claimed, with respect to the Fund, the exclusion from the definition of “commodity pool operator” under the CEA provided by CFTC Regulation 4.5 and is therefore not currently subject to registration or regulation as such under the CEA with respect to the Fund. In addition, the Sub-Adviser has claimed the exemption from registration as a commodity trading advisor provided by CFTC Regulation 4.14(a)(8) and is therefore not currently subject to registration or regulation as such under the CEA with respect to the Fund. In February 2012, the CFTC announced substantial amendments to certain exemptions, and to the conditions for reliance on those exemptions, from registration as a commodity pool operator. Under amendments to the exemption provided under CFTC Regulation 4.5, if the Fund uses futures, options on futures, or swaps other than for bona fide hedging purposes (as defined by the CFTC), the aggregate initial margin and premiums on these positions (after taking into account unrealized profits and unrealized losses on any such positions and excluding the amount by which options that are “in-the-money” at the time of purchase are “in-the-money”) may not exceed 5% of the Fund’s net asset value, or alternatively, the aggregate net notional value of those positions may not exceed 100% of the Fund’s net asset value (after taking into account unrealized profits and unrealized losses on any such positions). The CFTC amendments to Regulation 4.5 took effect on December 31, 2012, and the Fund intends to comply with amended Regulation 4.5’s requirements such that the Adviser will not be required to register as a commodity pool operator with the CFTC with respect to the Fund. The Fund reserves the right to employ futures, options on futures and swaps to the extent allowed by CFTC regulations in effect from time to time and in accordance with the Fund’s policies. However, the requirements for qualification as a “regulated investment company” under Subchapter M of the Code may limit the extent to which the Fund may employ futures, options on futures or swaps.

Structured Notes

The Fund may utilize structured notes and similar instruments for investment purposes and also for hedging purposes. Structured notes are privately negotiated debt obligations where the principal and/or interest is determined by reference to the performance of a benchmark asset, market or interest rate (an “embedded index”), such as selected securities, an index of securities or specified interest rates, or the differential performance of two assets or markets. The terms of such structured instruments normally provide that their principal and/or interest payments are to be adjusted upwards or downwards (but not ordinarily below zero) to reflect changes in the embedded index while the structured instruments are outstanding. As a result, the interest and/or principal payments that may be made on a structured product may vary widely, depending upon a variety of factors, including the volatility of the embedded index and the effect of changes in the embedded index on principal and/or interest payments. The rate of return on structured notes may be determined by applying a multiplier to the performance or differential performance of the referenced index or indices or other assets. Application of a multiplier involves leverage that will serve to magnify the potential for gain and the risk of loss.

Other Investment Companies

The Fund may invest up to 10% of its Managed Assets in securities of other open- or closed-end investment companies (including exchange-traded funds) that invest primarily in municipal

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securities of the types in which the Fund may invest directly. In addition, the Fund may invest a portion of its Managed Assets in pooled investment vehicles (other than investment companies) that invest primarily in municipal securities of the types in which the Fund may invest directly. The Fund generally expects that it may invest in other investment companies and/or other pooled investment vehicles either during periods when it has large amounts of uninvested cash or during periods when there is a shortage of attractive, high yielding municipal securities available in the market. The Fund may invest in investment companies that are advised by the Adviser and/or the Sub-Adviser or their affiliates to the extent permitted by applicable law and/or pursuant to exemptive relief from the SEC. No Fund has applied for, and no Fund currently intends to apply for, such relief. As a shareholder in an investment company, the Fund will bear its ratable share of that investment company’s expenses and would remain subject to payment of its own management fees with respect to assets so invested. Common shareholders would therefore be subject to duplicative expenses to the extent the Fund invests in other investment companies.

The Adviser and/or the Sub-Adviser will take expenses into account when evaluating the investment merits of an investment in an investment company relative to available municipal security investments. In addition, the securities of other investment companies may also be leveraged and will therefore be subject to the same leverage risks described herein. The net asset value and market value of leveraged shares will be more volatile, and the yield to common shareholders will tend to fluctuate more than the yield generated by unleveraged shares.

Zero Coupon Bonds

The Fund may invest in zero coupon bonds. A zero coupon bond is a bond that typically does not pay interest for the entire life of the obligation or for an initial period after the issuance of the obligation. The market prices of zero coupon bonds are affected to a greater extent by changes in prevailing levels of interest rates and therefore tend to be more volatile in price than securities that pay interest periodically. In addition, because the Fund accrues income with respect to these securities prior to the receipt of such interest, it may have to dispose of portfolio securities under disadvantageous circumstances in order to obtain cash needed to pay income dividends in amounts necessary to avoid unfavorable tax consequences.

Segregation of Assets

As a closed-end investment company registered with the SEC, the Fund is subject to the federal securities laws, including the 1940 Act, the rules thereunder, and various interpretive positions of the SEC and its staff. In accordance with these laws, rules and positions, the Fund must maintain liquid assets (often referred to as “asset segregation”), or engage in other SEC staff-approved measures, to “cover” open positions with respect to certain kinds of derivative instruments and financial agreements (such as reverse repurchase agreements). Generally, the Fund will maintain an amount of liquid assets with its custodian in an amount at least equal to the current amount of its obligations, including the value of unpaid past and future payment obligations, under derivative instruments and financial agreements, in accordance with SEC guidance. However, the Fund also may “cover” certain obligations by other means such as through ownership of the underlying security or financial instrument. The Fund also may enter into offsetting transactions with respect to certain obligations consistent with existing guidance from the SEC and its staff so that its combined position, coupled with any liquid assets maintained by its custodian, equals its net outstanding obligation in related derivatives or financial agreements. In the case of long positions in financial futures contracts that are not

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contractually required to cash settle, the Fund may set aside or earmark liquid assets or enter into offsetting positions equal to such contracts’ full notional value, less any margin on deposit for liquid assets, while the positions are open. In the case of short positions in financial futures contracts that are not contractually required to cash settle, the Fund may set aside or earmark liquid assets or enter into offsetting positions equal to such contracts’ current market value, less any margin on deposit for liquid assets, while the positions are open. With respect to financial futures contracts that are contractually required to cash settle, however, the Fund is permitted to set aside liquid assets or enter into an offsetting position in an amount equal to the Fund’s daily marked-tomarket net obligations (i.e., the Fund’s daily net liability) under the contracts, if any, rather than such contracts’ full notional value. If the Fund writes credit default swaps, it will segregate the full notional amount of the payment obligation under the credit default swap that must be paid upon the occurrence of a credit event. The Fund may invest in inverse floating rate securities issued by special purpose trusts. With respect to such investments, the Fund will segregate or earmark assets in an amount equal to at least 100% of the face amount of the floating rate securities issued by such trusts, plus accrued interest, if any.

The Fund reserves the right to modify its policies in the future to comply with any changes in the positions from time to time articulated by the SEC or its staff, such as the SEC’s proposed rule governing the use of derivatives by registered investment companies, regarding asset segregation.

To the extent the Fund uses its assets to cover its obligations as required by the 1940 Act, the rules thereunder, and applicable positions of the SEC and its staff, such assets may not be used for other operational purposes. Nuveen Fund Advisors and/or Nuveen Asset Management will monitor the Fund’s use of derivatives and will take action as necessary for the purpose of complying with the asset segregation policy stated above. Such actions may include the sale of the Fund’s portfolio investments.

The Fund may invest in inverse floating rate securities issued by special purpose trusts. With respect to such investments, the Fund will segregate or earmark assets in an amount equal to at least 100% of the face amount of the floating rate securities issued by such trusts.

Other Portfolio Investments, Investment Policies and Techniques and Investment Restrictions

See “Investment Restrictions” and “The Fund’s Investments” in the SAI for additional information.

USE OF LEVERAGE

The Fund uses leverage to pursue its investment objectives. The Fund may use leverage to the extent permitted by the Investment Company Act of 1940 (the “1940 Act”). The Fund may source leverage through a number of methods, including borrowings (including loans from financial institutions), issuances of debt securities, issuances of preferred shares of beneficial interest. The Fund may also use other forms of leverage including, but not limited to, reverse repurchase agreements and portfolio investments that have the economic effect of leverage, including, but not limited to, investments in inverse floating rate securities of tender option bond trusts.

Currently, the Fund employs leverage through its use of reverse repurchase agreements. The Fund also currently invests in residual interest certificates of tender option bond trusts, also called inverse floating rate securities, that have the economic effect of leverage because the Fund’s

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investment exposure to the underlying bonds held by the trust have been effectively financed by the trust’s issuance of floating rate certificates. As of July 31, 2020, the Fund’s leverage through reverse repurchase agreements and through investments in inverse floating rate securities was approximately 36% of its Managed Assets.

The Preferred Shares, if any, would have seniority over the Common Shares. Changes in the value of the Fund’s bond portfolio, including costs attributable to Preferred Shares, will be borne entirely by common shareholders. If there is a net decrease (or increase) in the value of the Fund’s investment portfolio, the leverage will decrease (or increase) the NAV per Common Share to a greater extent than if the Fund were not leveraged. For tax purposes, the Fund is currently required to allocate net capital gain and other taxable income, if any, between Common Shares and Preferred Shares in proportion to total dividends paid to each class for the year in which the net capital gain or other taxable income is realized. If net capital gain or other taxable income is allocated to Preferred Shares (instead of solely tax-exempt income), the Fund will likely have to pay higher total dividends to preferred shareholders or make special payments to preferred shareholders to compensate them for the increased tax liability. This would reduce the total amount of dividends paid to the common shareholders.

The Fund may also borrow for temporary purposes permitted by the 1940 Act. The Fund, along with the Participating Funds, are party to a committed Facility provided by a group of lender, under which Participating Funds may borrow for temporary purposes only. Outstanding balances drawn by the Fund, or any other Participating Fund, will bear interest at a variable rate and is the liability of such Fund. The Facility is not intended for sustained levered investment purposes. A large portion of the Facility’s capacity (and corresponding annual costs, excluding interest cost) is currently allocated by Nuveen Fund Advisors to a small number of Participating Funds, which does not include the Fund. The Facility has a 364-day term and will expire in June 2021 unless extended or renewed.

The Fund may reduce or increase leverage based upon changes in market conditions and anticipates that its leverage ratio will vary from time to time based upon variations in the value of the Fund’s holdings. So long as the net rate of income received on the Fund’s investments purchased with leverage proceeds exceeds the then current expense on any leverage, the investment of leverage proceeds will generate more net income than if the Fund had not used leverage. If so, the excess net income will be available to pay higher distributions to common shareholders. However, if the rate of net income received from the Fund’s portfolio investments purchased with leverage is less than the then current expense on outstanding leverage, the Fund may be required to utilize other Fund assets to make expense payments on outstanding leverage, which may result in a decline in Common Share NAV and reduced net investment income available for distribution to common shareholders. See “Risk Factors—Leverage Risk.”

Following an offering of additional Common Shares from time to time, the Fund’s leverage ratio will decrease as a result of the increase in net assets attributable to Common Shares. The Fund’s leverage ratio may decline further to the extent that the net proceeds of an offering of Common Shares are used to reduce the Fund’s leverage. A lower leverage ratio may result in lower (higher) returns to common shareholders over a period of time to the extent that net returns on the Fund’s investment portfolio exceed (fall below) its cost of leverage over that period, which lower (higher) returns may impact the level of the Fund’s distributions. See “Risk Factors—Leverage Risk.”

The Fund may use derivatives, such as interest rate swaps with varying terms, in order to manage the interest rate expense associated with all or a portion of its leverage. Interest rate swaps are

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bi-lateral agreements whereby parties agree to exchange future payments, typically based upon the differential of a fixed rate and a variable rate, on a specified notional amount. Interest rate swaps can enable a Fund to effectively convert its variable leverage expense to fixed, or vice versa. For example, if the Fund issues leverage having a short-term floating rate of interest, the Fund could use interest rate swaps to hedge against a rise in the short-term benchmark interest rates associated with its outstanding leverage. In doing so, the Fund would seek to achieve lower leverage costs, and thereby enhance Common Share distributions, over an extended period, which would be the result if short-term interest rates on average exceed the fixed interest rate over the term of the swap. To the extent the fixed swap rate is greater than short-term market interest rates on average over the period, overall costs associated with leverage will increase (and thereby reduce distributions to common shareholders) than if the Fund had not entered into the interest rate swap(s).

The Fund pays a management fee to Nuveen Fund Advisors (which in turn pays a portion of such fee to Nuveen Asset Management) based on a percentage of Managed Assets. Managed Assets include the proceeds realized and managed from the Fund’s use of most types of leverage (excluding the leverage exposure attributable to the use of futures, swaps and similar derivatives). Because Managed Assets include the Fund’s net assets as well as assets that are attributable to the Fund’s investment of the proceeds of its leverage (including instruments like inverse floating rate securities and reverse repurchase agreements), it is anticipated that the Fund’s Managed Assets will be greater than its net assets. Nuveen Fund Advisors will be responsible for using leverage to pursue the Fund’s investment objective. Nuveen Fund Advisors will base its decision regarding whether and how much leverage to use for the Fund, and the terms of that leverage, on its assessment of whether such use of leverage is in the best interests of the Fund. However, a decision to employ or increase leverage will have the effect, all other things being equal, of increasing Managed Assets, and in turn Nuveen Fund Advisors’ and Nuveen Asset Management fees. Thus, Nuveen Fund Advisors may have a conflict of interest in determining whether to use or increase leverage. Nuveen Fund Advisors will seek to manage that potential conflict by using leverage only when it determines that it would be in the best interests of the Fund and its common shareholders, and by periodically reviewing with the Board of Trustees the Fund’s performance, the Fund’s degree of overall use of leverage and the impact of the use of leverage on that performance.

The 1940 Act generally defines a “senior security” as any bond, debenture, note, or similar obligation or instrument constituting a security and evidencing indebtedness, and any stock of a class having priority over any other class as to distribution of assets or payment of dividends; however, the term does not include any promissory note or other evidence of indebtedness issued in consideration of any loan, extension, or renewal thereof, made for temporary purposes and in an amount not exceeding five percent of the value of the Fund’s total assets. A loan shall be presumed to be for temporary purposes if it is repaid within 60 days and is not extended or renewed.

Under the 1940 Act, the Fund is not permitted to issue “senior securities representing indebtedness” if, immediately after the issuance of such senior securities representing indebtedness, the asset coverage ratio with respect to such senior securities would be less than 300%. “Senior securities representing indebtedness” include borrowings (including loans from financial institutions); debt securities; and other derivative investments or transactions such as reverse repurchase agreements and investments in inverse floating rate securities to the extent the Fund has not fully covered, segregated or earmarked cash or liquid assets having a market value at least equal to its future obligation under such instruments. With respect to any such senior securities representing indebtedness, asset coverage means the ratio which the value of the total assets of the Fund, less all liabilities and indebtedness not

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represented by senior securities (as defined in the 1940 Act), bears to the aggregate amount of such borrowing represented by senior securities representing indebtedness issued by the Fund.

Under the 1940 Act, the Fund is not permitted to issue “senior securities” that are Preferred Shares if, immediately after the issuance of Preferred Shares, the asset coverage ratio with respect to such Preferred Shares would be less than 200%. With respect to any such Preferred Shares, asset coverage means the ratio which the value of the total assets of the Fund, less all liabilities and indebtedness not represented by senior securities, bears to the aggregate amount of senior securities representing indebtedness of the Fund plus the aggregate liquidation preference of such Preferred Shares.

The Fund is limited by certain investment restrictions and may only issue senior securities that are preferred shares except the Fund may borrow money from a bank for temporary or emergency purposes or for repurchase of its shares only in an amount not exceeding one-third of the Fund’s total assets (including the amount borrowed) less the Fund’s liabilities (other than borrowings). See “Investment Restrictions” in the SAI. These restrictions are fundamental and may not be changed without the approval of Common Shares and Preferred Shares voting together as a single class.

If the asset coverage with respect to any senior securities issued by the Fund declines below the required ratios discussed above (as a result of market fluctuations or otherwise), the Fund may sell portfolio securities when it may be disadvantageous to do so.

Certain types of leverage used by the Fund may result in the Fund being subject to certain covenants, asset coverage and, or other portfolio composition limits by its lenders, Preferred Share purchasers, liquidity providers, rating agencies that may rate Preferred Shares, or reverse repurchase agreement counterparties. Such limitations may be more stringent than those imposed by the 1940 Act and may affect whether the Fund is able to maintain its desired amount of leverage. At this time, Nuveen Fund Advisors does not believe that any such potential investment limitations will impede it from managing the Fund’s portfolio in accordance with its investment objective and policies.

Utilization of leverage is a speculative investment technique and involves certain risks to the common shareholders, including increased variability of the Fund’s net income, distributions and NAV in relation to market changes. See “Risk Factors—Leverage Risk.” There is no assurance that the Fund will use leverage or that the Fund’s use of leverage will work as planned or achieve its goals.

MANAGEMENT OF THE FUND

Trustees and Officers

The Board is responsible for the Fund’s management, including supervision of the duties performed by Nuveen Fund Advisors and Nuveen Asset Management. The names and business addresses of the trustees and officers of the Fund and their principal occupations and other affiliations during the past five years are set forth under “Management of the Fund” in the SAI.

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Investment Adviser, Sub-Adviser and Portfolio Manager

Investment Adviser

Nuveen Fund Advisors, LLC, the Fund’s investment adviser, is responsible for overseeing the Fund’s overall investment strategy and implementation. Nuveen Fund Advisors offers advisory and investment management services to a broad range of investment company clients. Nuveen Fund Advisors has overall responsibility for management of the Fund, oversees the management of the Fund’s portfolio, manages the Fund’s business affairs and provides certain clerical, bookkeeping and other administrative services. Nuveen Fund Advisors is located at 333 West Wacker Drive, Chicago, Illinois 60606. Nuveen Fund Advisors is a subsidiary of Nuveen, the investment management arm of Teachers Insurance and Annuity Association of America (“TIAA”). TIAA is a life insurance company founded in 1918 by the Carnegie Foundation for the Advancement of Teaching and is the companion organization of College Retirement Equities Fund. As of June 30, 2020, Nuveen managed approximately $1.05 trillion in assets, of which approximately $144.4 billion was managed by Nuveen Fund Advisors.

Sub-Adviser

Nuveen Asset Management, LLC, 333 West Wacker Drive, Chicago, Illinois 60606, serves as the Fund’s sub-adviser pursuant to a sub-advisory agreement between Nuveen Fund Advisors and Nuveen Asset Management (the “Sub-Advisory Agreement”). Nuveen Asset Management is a registered investment adviser, and a wholly-owned subsidiary of Nuveen Fund Advisors. Nuveen Asset Management oversees day-to-day investment operations of the Fund. Pursuant to the Sub-Advisory Agreement, Nuveen Asset Management is compensated for the services it provides to the Fund with a portion of the management fee Nuveen Fund Advisors receives from the Fund. Nuveen Fund Advisors and Nuveen Asset Management retain the right to reallocate investment advisory responsibilities and fees between themselves in the future.

Portfolio Manager

Nuveen Asset Management is responsible for the execution of specific investment strategies and day-to-day investment operations of the Fund. Nuveen Asset Management manages the Nuveen funds using a team of analysts and portfolio managers that focuses on a specific group of funds. The day-to-day operation of the Fund and the execution of its specific investment strategies is the primary responsibility of Daniel J. Close and John V. Miller, the designated portfolio manager of the Fund (the “Portfolio Managers”).

Daniel J. Close, CFA, Managing Director of Nuveen Asset Management, is the lead portfolio manager for Nuveen Asset Management’s taxable municipal strategies. He manages several state-specific municipal bond strategies and related institutional portfolios. He also serves as portfolio manager for national closed-end funds. He joined Nuveen Investments in 2000 as a member of Nuveen’s product management and development team. He then served as a research analyst for Nuveen’s municipal investing team, covering corporate-backed, energy, transportation and utility credits. He received his BS in Business from Miami University and his MBA from Northwestern University’s Kellogg School of Management. Mr. Close has earned the Chartered Financial Analyst designation.

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John V. Miller, CFA, serves as the head of Nuveen Municipals for Nuveen Asset Management, responsible for the investment process and performance of the firm’s municipal fixed income group. He is also the lead manager of the High Yield Municipal Bond Strategy, the California High Yield Municipal Bond Strategy, and related institutional portfolios. In addition, he co-manages the All-American Municipal Bond Strategy and the Strategic Municipal Opportunities Strategy and oversees a number of closed-end funds. Mr. Miller’s background features nearly 20 years of experience in the municipal marketplace. Before being named the co-head of Nuveen Municipals in 2011, he was chief investment officer for the firm’s municipal bond team starting in 2007. He was named a managing director and head of portfolio management for Nuveen Asset Management in 2006. Mr. Miller earned a B.A. in economics and political science from Duke University, an M.A. in economics from Northwestern University and an M.B.A. in finance with honors from the University of Chicago. He holds the Chartered Financial Analyst designation and is a member of the CFA Institute and the CFA Society of Chicago.

Additional information about the Portfolio Managers’ compensation, other accounts managed by the Portfolio Managers and the Portfolio Managers’ ownership of securities in the Fund is provided in the SAI. The SAI is available free of charge by calling (800) 257-8787 or by visiting the Fund’s website at www.nuveen.com. The information contained in, or that can be accessed through, the Fund’s website is not part of this prospectus or the SAI.

Investment Management and Sub-Advisory Agreements

Investment Management Agreement. Pursuant to an investment management agreement between Nuveen Fund Advisors and the Fund (the “Investment Management Agreement”), the Fund has agreed to pay an annual management fee for the services and facilities provided by Nuveen Fund Advisors, payable on a monthly basis, based on the sum of a fund-level fee and a complex-level fee, as described below.

Fund-Level Fee. The annual fund-level fee for the Fund, payable monthly, is calculated according to the following schedule:

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Complex Level Fee. The annual complex-level fee for the Fund, payable monthly, is calculated by multiplying the current complex-wide fee rate, determined according to the following schedule, by the Fund’s daily managed assets:

In addition to the fee of Nuveen Fund Advisors, the Fund pays all other costs and expenses of its operations, including compensation of its trustees (other than those affiliated with Nuveen Fund Advisors and Nuveen Asset Management), custodian, transfer agency and dividend disbursing expenses, legal fees, expenses of independent auditors, expenses of repurchasing shares, expenses associated with any borrowings, expenses of issuing any Preferred Shares, expenses of preparing, printing and distributing shareholder reports, notices, proxy statements and reports to governmental agencies, and taxes, if any. All fees and expenses are accrued daily and deducted before payment of dividends to investors.

A discussion regarding the basis for the Board’s decision to renew the Investment Management Agreement for the Fund may be found in the Fund’s annual report to shareholders dated March 31 of each year.

Sub-Advisory Agreement. Pursuant to the Sub-Advisory Agreement, Nuveen Asset Management will receive from Nuveen Fund Advisors a management fee equal to 53.8462% of Nuveen Fund Advisors’ net management fee from the Fund. Nuveen Fund Advisors and Nuveen Asset Management retain the right to reallocate investment advisory responsibilities and fees between themselves in the future.

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A discussion regarding the basis for the Board’s decision to renew the Sub-Advisory Agreement for the Fund may be found in the Fund’s semi-annual report to shareholders dated September 30 of each year.

NET ASSET VALUE

The Fund’s NAV per Common Share is determined as of the close of trading (normally 4:00 p.m. Eastern time) on each day the New York Stock Exchange is open for business. NAV is calculated by taking the fair value of the Fund’s total assets, including interest or dividends accrued but not yet collected, less all liabilities, and dividing by the total number of Common Shares outstanding. The result, rounded to the nearest cent, is the NAV per share.

The Fund’s custodian calculates the Fund’s NAV. The custodian uses prices for portfolio securities from a pricing service the Fund’s Board has approved. The pricing service values portfolio securities at the mean between the quoted bid and asked price or the yield equivalent when quotations are readily available. Securities for which quotations are not readily available (which will constitute the majority of the Fund’s portfolio securities) are valued at fair value as determined by the Board in reliance upon data supplied by the pricing service. The pricing service uses methods that consider yields or prices of municipal securities of comparable quality, type of issue, coupon, maturity, and ratings; dealers’ indications of value; and general market conditions. The pricing service may use electronic data processing techniques or a matrix system, or both. The Fund’s officers review the pricing service’s procedures and valuations, under the general supervision of the Board.

DISTRIBUTIONS

For a discussion of dividends and other distributions applicable to the Common Shares and the dividend reinvestment plan, see the prospectus supplement relating to the Common Shares being offered.

PLAN OF DISTRIBUTION

The Fund may sell Securities from time to time on an immediate, continuous or delayed basis, in one or more offerings under this prospectus and a related prospectus supplement in any one or more of the following ways: (1) directly to one or more purchasers, (2) through agents for the period of their appointment, (3) to underwriters as principals for resale to the public or (4) through, in the case of the Common Shares, in transactions that are deemed to be “at the market” as defined under Rule 415 under the 1933 Act.

The prospectus supplement will describe the method of distribution of the Securities offered therein.

Each prospectus supplement relating to an offering of Securities will state the terms of the offering, including:

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If any underwriters are involved in the offer and sale, the Securities will be acquired by the underwriters and may be resold by them, either at a fixed public offering price established at the time of offering or from time to time in one or more negotiated transactions or otherwise, at prices related to prevailing market prices determined at the time of sale. Unless otherwise set forth in the applicable prospectus supplement, the obligations of the underwriters to purchase the Securities will be subject to conditions precedent and the underwriters will be obligated to purchase all the Securities described in the prospectus supplement if any are purchased. Any initial public offering price and any discounts or concessions allowed or re-allowed or paid to dealers may be changed from time to time.

The Fund may offer and sell the Securities directly or through an agent or agents designated by the Fund from time to time. An agent may sell securities it has purchased from the Fund as principal to other dealers for resale to investors and other purchasers, and may reallow all or any portion of the discount received in connection with the purchase from the Fund to the dealers. After the initial offering of the Securities, the offering price (in the case of Securities to be resold at a fixed offering price), the concession and the discount may be changed. Any agent participating in the distribution of the Securities may be deemed to be an “underwriter,” as that term is defined in the 1933 Act, of the Securities so offered and sold.

Underwriters, dealers and agents may be entitled, under agreements entered into with the Fund, to indemnification by the Fund against some liabilities, including liabilities under the 1933 Act.

The place and time of delivery for the Securities in respect of which this prospectus is delivered will be set forth in the applicable prospectus supplement if appropriate.

Unless otherwise indicated in the prospectus supplement, each series of offered Preferred Shares will be a new issue of securities for which there currently is no market. Any underwriters to whom Preferred Shares are sold for public offering and sale may make a market in such Preferred Shares as permitted by applicable laws and regulations, but such underwriters will not be obligated to do so, and any such market making may be discontinued at any time without notice. Accordingly, there can be no assurance as to the development or liquidity of any market for the Preferred Shares.

Underwriters, agents and dealers may engage in transactions with or perform services, including various investment banking and other services, for the Fund and/or any of the Fund’s affiliates in the ordinary course of business.

The Fund will bear the expenses of the offering, including but not limited to, the expenses of preparation of this prospectus and the SAI and the prospectus supplement for the offering and the expense of counsel and auditors in connection with the offering.

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In compliance with the guidelines of the Financial Industry Regulatory Authority, Inc. (“FINRA”), the maximum commission or discount to be received by any member of FINRA or independent broker-dealer will not be greater than 9% of the initial gross proceeds from the sale of any Securities being sold.

To the extent permitted under the 1940 Act and the rules and regulations promulgated thereunder, the underwriters may from time to time act as a broker or dealer and receive fees in connection with the execution of the Fund’s portfolio transactions after the underwriters have ceased to be underwriters and, subject to certain restrictions, each may act as a broker while it is an underwriter.

CERTAIN PROVISIONS IN THE DECLARATION OF TRUST AND BY-LAWS

Under Massachusetts law, shareholders could, under certain circumstances, be held personally liable for the obligations of the Fund. However, the Declaration of Trust contains an express disclaimer of shareholder liability for debts or obligations of the Fund and requires that notice of such limited liability be given in each agreement, obligation or instrument entered into or executed by the Fund or the trustees. The Declaration of Trust further provides for indemnification out of the assets and property of the Fund for all loss and expense of any shareholder held personally liable for the obligations of the Fund. Thus, the risk of a shareholder incurring financial loss on account of shareholder liability is limited to circumstances in which the Fund would be unable to meet its obligations. The Fund believes that the likelihood of such circumstances is remote.

The Declaration of Trust and By-Laws include provisions that could limit the ability of other entities or persons to acquire control of the Fund or to convert the Fund to open-end status. The By-laws require the Board be divided into three classes with staggered terms. This provision of the By-laws could delay for up to two years the replacement of a majority of the Board. Preferred shareholders voting as a separate class, will be entitled to elect two of the Fund’s trustees. In addition, the Declaration of Trust includes other provisions that could limit the ability of other entities or persons to acquire control of the Fund or to convert the Fund to open-end status. Specifically, the Declaration of Trust requires a vote by holders of at least two-thirds of the Common Shares and Preferred Shares voting together as a single class, except as described below, to authorize (1) a conversion of the Fund from a closed-end to an open-end investment company, (2) a merger or consolidation of the Fund, or a series or class of the Fund, with any corporation, association, trust or other organization or a reorganization or recapitalization of the Fund, or a series or class of the Fund, (3) a sale, lease or transfer of all or substantially all of the Fund’s assets (other than in the regular course of the Fund’s investment activities), (4) in certain circumstances, a termination of the Fund, or a series or class of the Fund, or (5) a removal of trustees (voting by class or classes of shares that elected such trustee) by shareholders, and then only for cause, unless, with respect to (1) through (4), such transaction has already been authorized by the affirmative vote of two-thirds of the total number of trustees fixed in accordance with the Declaration of Trust or the By-Laws, in which case the affirmative vote of the holders of at least a majority of the Fund’s Common Shares and Preferred Shares voting together as a single class, is required; provided, however, that where only a particular class or series is affected, only the required vote by the applicable class or series will be required. For purposes of the foregoing, the term “recapitalization” shall not mean, without limitation, the issuance or redemption of Preferred Shares pursuant to the terms of the Declaration of Trust or the statement adopted with respect to such Preferred Shares, whether or not in conjunction with the issuance, retirement or redemption of other securities or indebtedness of the Fund. Approval of shareholders is not required, however, for any transaction, whether deemed a merger, consolidation, reorganization or otherwise whereby the Fund

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issues shares in connection with the acquisition of assets (including those subject to liabilities) from any other investment company or similar entity. In the case of the conversion of the Fund to an open-end investment company, or in the case of any of the foregoing transactions constituting a plan of reorganization which adversely affects the holders of Preferred Shares, if any, the action in question will also require the affirmative vote of the holders of at least two-thirds of the Fund’s Preferred Shares, outstanding at the time, voting as a separate class, or, if such action has been authorized by the affirmative vote of two-thirds of the total number of trustees fixed in accordance with the Declaration of Trust or the By-Laws, the affirmative vote of the holders of at least a majority of the Fund’s Preferred Shares outstanding at the time, voting as a separate class. None of the foregoing provisions may be amended except by the vote of at least two-thirds of the Common Shares and Preferred Shares voting together as a single class. The votes required to approve the conversion of the Fund from a closed-end to an open-end investment company or to approve transactions constituting a plan of reorganization which adversely affects the holders of Preferred Shares are higher than those required by the 1940 Act. The Board believes that the provisions of the Declaration of Trust relating to such higher votes are in the best interest of the Fund and its shareholders. Under the Fund’s By-Laws, the Board is divided into three classes and such a staggered board could delay for up to two years the replacement of a majority of the Board.

The Declaration of Trust provides that the obligations of the Fund are not binding upon the Fund’s trustees individually, but only upon the assets and property of the Fund, and that the trustees shall not be liable for errors of judgment or mistakes of fact or law. Nothing in the Declaration of Trust, however, protects a trustee against any liability to which he or she would otherwise be subject by reason of willful misfeasance, bad faith, gross negligence or reckless disregard of the duties involved in the conduct of his or her office.

The provisions of the Declaration of Trust described above could have the effect of depriving the shareholders of opportunities to sell their Common Shares at a premium over the then current market price of the Common Shares by discouraging a third party from seeking to obtain control of the Fund in a tender offer or similar transaction. The overall effect of these provisions is to render more difficult the accomplishment of a merger or the assumption of control by a third party. They provide, however, the advantage of potentially requiring persons seeking control of the Fund to negotiate with its management regarding the price to be paid and facilitating the continuity of the Fund’s investment objectives and policies. The Board has considered the foregoing anti-takeover provisions and concluded that they are in the best interests of the Fund and its shareholders.

Reference should be made to the Declaration of Trust and By-Laws on file with the SEC for the full text of these provisions.

REPURCHASE OF FUND SHARES; CONVERSION TO OPEN-END FUND

The Fund is a closed-end investment company and as such its shareholders will not have the right to cause the Fund to redeem their shares. Instead, the Common Shares trade in the open market at prices that are a function of several factors, including Common Share dividend levels (which are in turn affected by expenses) in comparison to market rates for similar investments, NAV, call protection, dividend stability, portfolio credit quality, relative demand for and supply of such shares in the market, general market and economic conditions and other factors. Because shares of closed-end investment companies may frequently trade at prices lower than NAV, the Board has currently determined that, at least annually, it will consider action that might be taken to reduce or eliminate any material discount

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from NAV in respect of Common Shares, which may include the repurchase of such shares in the open market or in private transactions, the making of a tender offer for such shares at NAV, or the conversion of the Fund to an open-end investment company. The Fund cannot assure you that its Board will decide to take any of these actions, or that share repurchases or tender offers will actually reduce market discount.

Notwithstanding the foregoing, at any time when the Fund’s Preferred Shares are outstanding, the Fund may not purchase, redeem or otherwise acquire any of its Common Shares unless (1) all accumulated but unpaid dividends on Preferred Shares due to be paid have been paid and (2) at the time of such purchase, redemption or acquisition, the NAV of the Fund’s portfolio (determined after deducting the acquisition price of the Common Shares) is at least 200% of the liquidation value of the outstanding Preferred Shares (expected to equal the original purchase price per share plus any accumulated but unpaid dividends thereon). Any service fees incurred in connection with any tender offer made by the Fund will be borne by the Fund and will not reduce the stated consideration to be paid to tendering shareholders.

Subject to its investment limitations, the Fund may borrow to finance the repurchase of shares or to make a tender offer. Interest on any borrowings to finance share repurchase transactions or the accumulation of cash by the Fund in anticipation of share repurchases or tenders will reduce the Fund’s net income. Any share repurchase, tender offer or borrowing that might be approved by the Board would have to comply with the Securities Exchange Act of 1934, as amended (the “1934 Act”), and the 1940 Act and the rules and regulations thereunder.

Although the decision to take action in response to a discount from NAV will be made by the Board at the time it considers such issue, it is the Board’s present policy, which may be changed by the Board, not to authorize repurchases of Common Shares or a tender offer for such shares if (1) such transactions, if consummated, would (a) result in the delisting of the Common Shares from the NYSE, or (b) impair the Fund’s status as a regulated investment company under the Code, as amended (which would make the Fund a taxable entity, causing the Fund’s income to be taxed at the corporate level in addition to the taxation of shareholders who receive dividends from the Fund), or as a registered closed-end investment company under the 1940 Act; (2) the Fund would not be able to liquidate portfolio securities in an orderly manner and consistent with the Fund’s investment objectives and policies in order to repurchase shares; or (3) there is, in the Board’s judgment, any (a) material legal action or proceeding instituted or threatened challenging such transactions or otherwise materially adversely affecting the Fund, (b) general suspension of or limitation on prices for trading securities on the NYSE, (c) declaration of a banking moratorium by federal or state authorities or any suspension of payment by United States or state banks in which the Fund invests, (d) material limitation affecting the Fund or the issuers of its portfolio securities by federal or state authorities on the extension of credit by lending institutions or on the exchange of foreign currency, (e) commencement of war, armed hostilities or other international or national calamity directly or indirectly involving the United States, or (f) other event or condition which would have a material adverse effect (including any adverse tax effect) on the Fund or its shareholders if shares were repurchased. The Board may in the future modify these conditions in light of experience.

Conversion to an open-end company would require the approval of the holders of at least two-thirds of the Fund’s Common Shares and Preferred Shares outstanding at the time, voting together as a single class, and of the holders of at least two-thirds of the Fund’s Preferred Shares outstanding at the time, voting as a separate class; provided, however, that such separate class vote shall be a majority

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vote if the action in question has previously been approved, adopted or authorized by the affirmative vote of two-thirds of the total number of trustees fixed in accordance with the Declaration of Trust or By-Laws. See “Certain Provisions in the Declaration of Trust and By-Laws” for a discussion of voting requirements applicable to conversion of the Fund to an open-end company. If the Fund converted to an open-end investment company, it would be required to redeem all Preferred Shares then outstanding (requiring in turn that it liquidate a portion of its investment portfolio), and the Common Shares would no longer be listed on the NYSE. In contrast to a closed-end investment company, shareholders of an open-end investment company may require the company to redeem their shares at any time (except in certain circumstances as authorized by or under the 1940 Act) at their NAV, less any redemption charge that is in effect at the time of redemption. In order to avoid maintaining large cash positions or liquidating favorable investments to meet redemptions, open-end companies typically engage in a continuous offering of their shares. Open-end companies are thus subject to periodic asset in-flows and out-flows that can complicate portfolio management. As a result, conversion to open-end status may require changes in the management of the Fund’s portfolio in order to meet the liquidity requirements applicable to open-end funds. Because portfolio securities may have to be liquidated to meet redemptions, conversion could affect the Fund’s ability to meet its investment objectives or to use certain investment policies and techniques described above. If converted to an open-end fund, the Fund expects to pay all redemptions in cash, but intends to reserve the right to pay redemption requests in a combination of cash or securities. If such partial payment in securities were made, investors may incur brokerage costs in converting such securities to cash. If the Fund were converted to an open-end fund, new Common Shares may be sold at NAV plus a sales load. The Board may at any time propose conversion of the Fund to an open-end company depending upon their judgment as to the advisability of such action in light of circumstances then prevailing.

The repurchase by the Fund of its Common Shares at prices below NAV will result in an increase in the NAV of those shares that remain outstanding. However, there can be no assurance that share repurchases or tenders at or below NAV will result in the Common Shares trading at a price equal to their NAV. Nevertheless, the fact that the Common Shares may be the subject of repurchase or tender offers at NAV from time to time, or that the Fund may be converted to an open-end company, may reduce any spread between market price and NAV that might otherwise exist.

In addition, a purchase by the Fund of its Common Shares will decrease the Fund’s total assets which would likely have the effect of increasing the Fund’s expense ratio. Any purchase by the Fund of its Common Shares at a time when Preferred Shares are outstanding will increase the leverage applicable to the outstanding Common Shares then remaining.

Before deciding whether to take any action if the Common Shares trade below NAV, the Board of Trustees would consider all relevant factors, including the extent and duration of the discount, the liquidity of the Fund’s portfolio, the impact of any action that might be taken on the Fund or its shareholders, and market considerations. Based on these considerations, even if the Common Shares should trade at a discount, the Board may determine that, in the interest of the Fund and its shareholders, no action should be taken. On August 4, 2020, the Fund’s Board renewed the Fund’s open market share repurchase program under which the Fund may repurchase up to 10% of its Common Shares. Since the inception of the Fund’s share repurchase program through August 18, 2020, the Fund has not repurchased any Common Shares under the program.

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TAX MATTERS

The following information is meant as a general summary for U.S. holders of an investment in the shares of the Fund. Please see the SAI for additional information. A description of material U.S. federal income tax consequences relating to the purchase and ownership of any Common Shares or Preferred Shares being offered will be set forth in the related prospectus supplement. Investors should rely on their own tax adviser for advice about the particular federal, state and local tax consequences to them of investing in the Fund.

The recent tax legislation commonly referred to as the Tax Cuts and Jobs Act (the “Tax Act”) made significant changes, generally effective for taxable years beginning after December 31, 2017, to the U.S. federal income tax rules for individuals and corporations. Many of the changes affecting individuals apply only for taxable years beginning after December 31, 2017 and before January 1, 2026. There were only minor changes to the rules specifically affecting RICs, such as the Fund. The Tax Act, however, made numerous other changes to the tax rules affecting shareholders and the Fund. You are urged to consult your own tax advisor regarding how the Tax Act affects your investment in the Fund.

The Fund has elected and intends to qualify each year as a RIC under Subchapter M of the Code. In order to qualify for treatment as a RIC, the Fund must satisfy certain requirements regarding the sources of its income, the diversification of its assets and the distribution of its income. As a RIC, the Fund generally does not expect to have to pay U.S. federal income tax. The Fund primarily invests in municipal securities (as defined above) issued by states, cities and local authorities and certain possessions and territories of the United States (such as Puerto Rico or Guam) or municipal securities the income of which is otherwise exempt from regular U.S. federal income taxes. To qualify to pay exempt-interest dividends, which are treated as items of interest excludable from gross income for U.S. federal income tax purposes, at least 50% of the value of the total assets of the Fund must consist of obligations exempt from regular income tax as of the close of each quarter of the Fund’s taxable year. If the proportion of taxable investments held by the Fund exceeds 50% of the Fund’s total assets as of the close of any quarter of any Fund taxable year, the Fund would not for that taxable year satisfy the general eligibility test that would otherwise permit it to pay exempt-interest dividends. Substantially all of the Fund’s dividends paid to you are expected to qualify as “exempt-interest dividends,” which are exempt from regular U.S. federal income tax. The Fund does not intend to acquire securities the income of which is subject to the federal alternative minimum tax applicable to individuals. The Tax Act repealed the federal alternative minimum tax for corporations for tax years beginning after December 31, 2017.

The exemption from U.S. federal income tax for exempt-interest dividends does not necessarily result in exemption for such dividends under the income or other tax laws of any state or local taxing authority. Some states exempt from state income tax that portion of any exempt-interest dividend that is derived from interest received by a RIC on its holdings of securities of that state and its political subdivisions and instrumentalities. Therefore, the Fund will report annually to its shareholders the percentage of interest income earned by the fund during the preceding year on tax-exempt obligations indicating, on a state-by-state basis, the source of such income. Shareholders of the Fund are advised to consult with their own tax advisers about state and local tax matters.

In addition to exempt-interest dividends, the Fund may also distribute to its shareholders amounts that are treated as long-term capital gain or ordinary income (which may include short-term

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capital gains). These distributions are generally subject to regular U.S. federal income tax, whether or not reinvested in additional shares. Capital gain distributions are generally taxable at rates applicable to long-term capital gains regardless of how long a shareholder has held its shares. Long-term capital gains are taxable to non-corporate shareholders at rates of up to 20%. The Fund does not expect that any part of its distributions to shareholders from its investments will qualify for the dividends-received deduction available to corporate shareholders or as “qualified dividend income,” which is taxable to non-corporate shareholders at reduced maximum U.S. federal income tax rates.

A 3.8% Medicare contribution tax generally applies to all or a portion of the net investment income of a shareholder that is an individual and not a nonresident alien for U.S. federal income tax purposes and that has adjusted gross income (subject to certain adjustments) that exceeds a threshold amount ($250,000 if married filing jointly or if considered a “surviving spouse” for U.S. federal income tax purposes, $125,000 if married filing separately, and $200,000 in other cases). This 3.8% tax also applies to all or a portion of the undistributed net investment income of certain shareholders that are estates and trusts. For these purposes, interest, dividends and certain capital gains are generally taken into account in computing a shareholder’s net investment income, but exempt-interest dividends are not taken into account.

As a RIC, the Fund will not have to pay U.S. federal income tax in any taxable year provided that it meets certain requirements. The Fund might not distribute some (or all) of its net capital gain. If the Fund does not distribute all of its net capital gain and net investment income, it will be subject to tax at the corporate rate on the amount retained. If the Fund retains any net capital gain, it may designate the retained amount as undistributed capital gains in a notice to its shareholders that, if subject to U.S. federal income tax on long-term capital gains, (i) will be required to include in income for U.S. federal income tax purposes, as long-term capital gain, their share of such undistributed amount; (ii) will be deemed to have paid their proportionate shares of the tax paid by the Fund on such undistributed amount and will be entitled to credit that amount of tax against their U.S. federal income tax liabilities, if any; and (iii) will be entitled to claim refunds to the extent the credit exceeds such liabilities. For U.S. federal income tax purposes, the tax basis of shares owned by a shareholder of the Fund will be increased by an amount equal to the difference between the amount of undistributed capital gains included in the shareholder’s gross income and the tax deemed paid by the shareholder.

The Internal Revenue Service (the “IRS”) requires that a RIC that has two or more classes of stock allocate to each such class proportionate amounts of each type of its income (such as exempt interest, ordinary income and capital gains). Accordingly, the Fund reports dividends made with respect to Common Shares and Preferred Shares as consisting of particular types of income (e.g., exempt interest, net capital gains and ordinary income) in accordance with each class’ proportionate share of the total dividends paid by the Fund with respect to the year.

Dividends declared by the Fund in October, November or December, payable to shareholders of record in such a month, and paid during the following January will be treated as having been received by shareholders in the year the distributions were declared.

Each shareholder will receive an annual statement summarizing the U.S. federal income tax status of all distributions.

The repurchase, sale or exchange of shares normally will result in capital gain or loss to holders that hold their shares as capital assets. Generally a shareholder’s gain or loss will be long-term capital

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gain or loss if the shares have been held for more than one year even though the increase in value in such shares may be at least partly attributable to tax-exempt interest income. For corporate taxpayers, both long-term and short-term capital gains are taxed at the same rate that applies to ordinary income. For non-corporate taxpayers, however, long-term capital gains are taxed at rates of up to 20%. Short-term capital gains and other ordinary income are taxed to non-corporate taxpayers at ordinary income rates. If a shareholder sells or otherwise disposes of shares before holding them for six months, any loss on the sale or disposition will be treated as a long-term capital loss to the extent of any amounts treated as distributions to the holder of long-term capital gain (including any amount credited to the holder as undistributed capital gain). Any loss realized by a shareholder on the disposition of shares held six months or less is disallowed to the extent of the amount of exempt-interest dividends received by the shareholder with respect to shares of the Fund. Any loss realized on a sale or exchange of shares of the Fund will be disallowed to the extent those shares of the Fund are replaced by substantially identical shares of the Fund (including shares acquired by reason of participation in the dividend reinvestment plan) within a period of 61 days beginning 30 days before and ending 30 days after the date of disposition of the original shares, or to the extent the shareholder enters into a contract or option to repurchase shares within such period. In that event, the basis of the replacement shares of the Fund will be adjusted to reflect the disallowed loss.

Any interest on indebtedness incurred or continued to purchase or carry the Fund’s shares to which exempt-interest dividends are allocated is not deductible. Under certain applicable rules, the purchase or ownership of shares may be deemed to have been made with borrowed funds even though such funds are not directly used for the purchase or ownership of the shares. In addition, if you receive social security or certain railroad retirement benefits, you may be subject to U.S. federal income tax on a portion of such benefits as a result of receiving investment income, including exempt-interest dividends and other distributions paid by the Fund.

The Fund may be required to withhold (as “backup withholding”) U.S. federal income tax for distributions (including exempt-interest dividends) and repurchase proceeds payable to a shareholder if the shareholder fails to provide the Fund with his or her correct taxpayer identification number or to make required certifications, or if the shareholder has been notified by the IRS that he or she is subject to backup withholding. The backup withholding rate is 24%. Backup withholding is not an additional tax; rather, it is a way in which the IRS ensures it will collect taxes otherwise due. Any amounts withheld may be credited against a shareholder’s U.S. federal income tax liability.

The Fund may invest a portion of its assets in securities that generate income that is not exempt from regular U.S. federal income tax.

With respect to Preferred Shares of the Fund, the Fund will receive prior to issuance an opinion from special tax counsel that the Preferred Shares will constitute stock of the Fund, and the foregoing discussion relies on the position that the Preferred Shares will constitute stock of the Fund. Accordingly, distributions with respect to the Preferred Shares (other than distributions in redemption of Preferred Shares subject to Section 302(b) of the Code) will generally constitute dividends to the extent of the Fund’s current or accumulated earnings and profits, as calculated for U.S. federal income tax purposes and to the extent allocable to such distribution. Because the treatment of a corporate security as debt or equity is determined on the basis of the facts and circumstances of each case, and no controlling precedent exists for the Preferred Shares, there can be no assurance that the IRS will not question special tax counsel’s opinion and the Fund’s treatment of the Preferred Shares as stock. If the IRS were to succeed in such a challenge, holders of Preferred Shares could be treated as having

63

received taxable interest or dividends rather than exempt-interest dividends, which could possibly require them to file amended income tax returns, report additional taxable income and pay additional tax, interest and penalties.

State and Local Tax Matters. The exemption from U.S. federal income tax for exempt-interest dividends generally does not result in exemption for such dividends under the income or other tax laws of any state or local taxing authority. In some states, however, the portion of any exempt-interest dividends derived from interest received by the Fund on its holdings of that state’s securities and those of its political subdivisions and instrumentalities is exempt from the state’s income tax. The Fund will report annually to its shareholders the percentage of interest income earned by the Fund during the preceding year on tax-exempt obligations indicating, on a state-by-state basis, the source of such income. Shareholders of the Fund are advised to consult their own tax advisors about state and local tax matters.

Please refer to the SAI for more detailed information.

CUSTODIAN AND TRANSFER AGENT

The custodian of the Fund’s assets is State Street Bank and Trust Company, One Lincoln Street, Boston, Massachusetts 02111 (the “Custodian”). The Custodian performs custodial, fund accounting and portfolio accounting services. The Fund’s transfer, shareholder services and dividend paying agent is Computershare Inc. and Computershare Trust Company, N.A. Computershare is located at 250 Royall Street, Canton, Massachusetts 02021.

LEGAL MATTERS

Certain legal matters in connection with the Common Shares will be passed upon for the Fund by Morgan, Lewis & Bockius LLP, Washington, D.C.

INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

KPMG LLP (“KPMG”), an independent registered public accounting firm, provides auditing services to the Fund. The principal business address of KPMG is 200 East Randolph Street, Chicago, Illinois 60601.

AVAILABLE INFORMATION

The Fund is subject to the informational requirements of the Securities Exchange Act of 1934, as amended (the “Exchange Act”) and the 1940 Act and is required to file reports, proxy statements and other information with the SEC. The Fund incorporates by reference into this prospectus supplement its latest annual report on Form N-CSR for the fiscal period ended March 31, 2020. In addition, all documents subsequently filed by the Fund pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act also are incorporated into this Prospectus by reference. Reports, proxy statements, and other information about the Fund can be inspected at the offices of the NYSE and at http://[    ].

This Prospectus does not contain all of the information in the Fund’s Registration Statement, including amendments, exhibits, and schedules. Additional information about the Fund and the Common Shares can be found in the Fund’s Registration Statement (including amendments, exhibits, and schedules) on Form N-2 filed with the SEC. The SEC maintains a web site (http://www.sec.gov) that contains the Fund’s Registration Statement, other documents incorporated by reference, and other information the Fund has filed electronically with the SEC, including proxy statements and reports filed under the Exchange Act.

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The information in this preliminary prospectus supplement is not complete and may be changed. A registration statement relating to these securities was filed with the Securities and Exchange Commission and became effective. This preliminary prospectus supplement and the accompanying prospectus are not an offer to sell these securities and we are not soliciting offers to buy these securities in any jurisdiction where the offer or sale is not permitted.

Subject to Completion

Preliminary Prospectus Supplement dated [•], 2020

PROSPECTUS SUPPLEMENT

(To Prospectus dated [•] 2020)

[Up to $[•]]

Nuveen Taxable Municipal Income Fund

[[•]] COMMON SHARES, $0.01 PAR VALUE PER SHARE

Nuveen Taxable Municipal Income Fund (the “Fund”), a diversified, closed-end management investment company, is offering [up to $[•] of its][[•] common shares, $0.01 par value per share (the “Common Shares”), pursuant to this prospectus supplement.

The minimum price on any day at which Common Shares may be sold will not be less than the current net asset value (“NAV”) per share plus the per share amount of the commission to be paid to the Fund’s distributor, Nuveen Securities, LLC (“Nuveen Securities” or the “Agent”). The Fund and Nuveen Securities will suspend the sale of Common Shares if the per share price of the shares is less than the minimum price. The Fund currently intends to distribute the shares offered pursuant to this prospectus supplement primarily through at-the-market transactions, although from time to time it may also distribute shares through an underwriting syndicate or a privately negotiated transaction. To the extent shares are distributed other than through at-the-market transactions, the Fund will file a supplement describing such transactions. For information on how Common Shares may be sold, see the “Plan of Distribution” section of this prospectus supplement.

Common Shares are listed on the New York Stock Exchange (the “NYSE”) under the symbol “NBB.” The closing price for the Common Shares on the NYSE on [•], 2020 was $[•]. The NAV of the Common Shares at the close of business on [•], 2020 was $[•] per Common Share.

Common shares of closed-end investment companies, such as the Fund, often trade at a discount to their NAV. This creates a risk of loss for an investor purchasing common shares in a public offering.

Investing in the Common Shares involves risks. See “Risk Factors” beginning on page S-11 of this prospectus supplement and on page 10 of the accompanying prospectus. You should consider carefully these risks together with all of the other information in this prospectus supplement and the accompanying prospectus before making a decision to purchase Common Shares.

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(continued from previous page)

The Fund’s primary investment objective is to provide current income through investments in taxable municipal securities. As a secondary objective, the Fund seeks to enhance portfolio value and total return. The Fund seeks to achieve its investment objectives by investing primarily in a diversified portfolio of taxable municipal securities. There can be no assurance that the Fund will achieve its investment objectives.

Under normal circumstances, the Fund will invest at least 80% of its Assets in taxable municipal securities. The Fund may invest up to 20% of its Assets in securities other than taxable municipal securities, including municipal securities the interest income from which is exempt from regular federal income tax (sometimes referred to as “tax-exempt municipal securities”), U.S. Treasury securities and obligations of the U.S. Government, its agencies and instrumentalities. The Fund may purchase taxable municipal securities (including for purposes of the 80% test) and other tax-exempt municipal securities in the form of bonds, notes, leases or certificates of participation; structured as callable or non-callable; with payment forms that include fixed-coupon, variable rate, zero coupon, capital appreciation bonds, floating rate securities, inverse floating rate securities and other derivative instruments that replicate investment exposure to taxable municipal securities or other municipal securities. Such municipal securities may be acquired through investments in pooled vehicles, partnerships or other investment companies. The Fund may also purchase municipal securities representing a wide range of sectors and purposes. Under normal circumstances, the Fund will invest at least 80% of its Managed Assets in securities that at the time of investment are investment grade quality. A security is considered investment grade quality if it is rated within the four highest letter grades (BBB or Baa or better) by at least one of the nationally recognized statistical rating organizations (“NRSROs”) that rate such security (even if it is rated lower by another), or if it is unrated by any NRSRO but judged to be of comparable quality by Nuveen Asset Management. Under normal circumstances, the Fund may invest up to 20% of its Managed Assets in securities rated below investment grade or are unrated by any NRSRO but judged to be of comparable quality by Nuveen Asset Management. Municipal securities of below investment grade quality are regarded as having predominantly speculative characteristics with respect to capacity to pay interest and repay principal, and are commonly referred to as junk bonds.

Beginning on January 1, 2021, as permitted by regulations adopted by the SEC, paper copies of the Fund’s shareholder reports will not be sent by mail, unless you specifically request paper copies of the shareholder reports from the Fund or from your financial intermediary, such as a broker-dealer or bank. Instead, shareholder reports will be available on the Fund’s website at http://www.nuveen.com, and you will be notified by mail each time a report is posted and provided with a website link to access the report. If you already elected to receive shareholder reports electronically, you will not be affected by this change and you need not take any action. You may elect to receive shareholder reports and other communications from the Fund electronically anytime by contacting your financial intermediary, such as a broker-dealer or bank, through which you hold your Common Shares. Shareholders may at any time elect to receive paper copies of the shareholder reports without charge by contacting your financial intermediary or by contacting the Fund by calling (800) 257-8787 or by writing to 333 West Wacker Drive, Chicago, Illinois 60606.

(continued from previous page)

You should read this prospectus supplement, together with the accompanying prospectus, which contains important information about the Fund, before deciding whether to invest in Common Shares and retain it for future reference. A statement of additional information, dated [•], 2020, and as it may be supplemented (the “SAI”), containing additional information about the Fund, has been filed with the SEC and is incorporated by reference in its entirety into this prospectus supplement and the accompanying prospectus. You may request a free copy of the SAI, annual and semi-annual reports to shareholders, when available, and other information about the Fund, and make shareholder inquiries by calling (312) 917-7700 or by writing to the Fund, or from the Fund’s website (www.nuveen.com). The information contained in, or that can be accessed through, the Fund’s website is not part of this prospectus supplement, the accompanying prospectus or the SAI. You also may obtain a copy of the SAI (and other information regarding the Fund) from the SEC’s website (www.sec.gov).

Common Shares do not represent a deposit or obligation of, and are not guaranteed or endorsed by, any bank or other insured depository institution, and are not federally insured by the Federal Deposit Insurance Corporation, the Federal Reserve Board or any other government agency.

Neither the U.S. Securities and Exchange Commission (the “SEC”) nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus supplement or the accompanying prospectus. Any representation to the contrary is a criminal offense.

TABLE OF CONTENTS

Prospectus Supplement

Prospectus

You should rely only on the information contained or incorporated by reference into this prospectus supplement and the accompanying prospectus. The Fund has not authorized anyone to provide you with different information. If anyone provides you with different or inconsistent information, you should not rely on it. The Fund is not making an offer of Common Shares in any state where the offer is not permitted. You should not assume that the information contained in this prospectus supplement and the accompanying prospectus is accurate as of any date other than the respective dates on the front covers. The Fund’s business, financial condition and prospects may have changed since that date.

i

FORWARD-LOOKING STATEMENTS

Any projections, forecasts and estimates contained or incorporated by reference herein are forward looking statements and are based upon certain assumptions. Projections, forecasts and estimates are necessarily speculative in nature, and it can be expected that some or all of the assumptions underlying any projections, forecasts or estimates will not materialize or will vary significantly from actual results. Actual results may vary from any projections, forecasts and estimates and the variations may be material. Some important factors that could cause actual results to differ materially from those in any forward looking statements include changes in interest rates, market, financial or legal uncertainties, including changes in tax law, and the timing and frequency of defaults on underlying investments. Consequently, the inclusion of any projections, forecasts and estimates herein should not be regarded as a representation by the Fund or any of its affiliates or any other person or entity of the results that will actually be achieved by the Fund. Neither the Fund nor its affiliates has any obligation to update or otherwise revise any projections, forecasts and estimates including any revisions to reflect changes in economic conditions or other circumstances arising after the date hereof or to reflect the occurrence of unanticipated events, even if the underlying assumptions do not come to fruition. The Fund acknowledges that, notwithstanding the foregoing, the safe harbor for forward-looking statements under the Private Securities Litigation Reform Act of 1995 does not apply to investment companies such as the Fund.

ii

PROSPECTUS SUPPLEMENT SUMMARY

This is only a summary. You should review the more detailed information contained elsewhere in this prospectus supplement, in the accompanying prospectus and in the statement of additional information, dated [•], 2020, and as it may be supplemented (the “SAI”), including the documents incorporated by reference, prior to making an investment in the Fund, especially the information set forth under the heading “Risk Factors” beginning on page S-11 of this prospectus supplement and beginning on page 10 in the accompanying prospectus.

S-1

S-2

S-3

S-4

S-5

S-6

S-7

S-8

S-9

S-10

RISK FACTORS

Investing in the Common Shares involves risk, including the risk that you may receive little or no return on your investment or that you may lose part or all of your investment. Therefore, before investing in the Common Shares you should consider carefully the following risks, as well as the risk factors set forth under “Risk Factors” beginning on page 10 of the accompanying prospectus.

Investment and Market Risk

An investment in the shares of the Fund is subject to investment risk, including the possible loss of the entire principal amount that you invest. Your investment in shares represents an indirect investment in the municipal securities owned by the Fund. Your shares at any point in time may be worth less than your original investment, even after taking into account the reinvestment of dividends and distributions, if applicable. In addition, the ability of municipalities to collect revenue and service their obligations could be materially and adversely affected by an economic downturn or prolonged recession. Because certain states, including California, New York, Illinois, Texas and Ohio, were heavy issuers of BABs, the Fund may have a greater exposure to the economic or other factors affecting such states than a more diversified national municipal bond fund. Investors bear a risk of loss to the extent that the price at which they sell their shares is lower than at the time of purchase. The shares of the Fund are designed primarily for long-term investors, and you should not view the Fund as a vehicle for trading purposes.

Market Discount to Net Asset Value

Shares of closed-end investment companies like the Fund have during some periods traded at prices higher than NAV and have during other periods traded at prices lower than NAV. The Fund cannot predict whether Common Shares will trade at, above or below NAV. This characteristic is a risk separate and distinct from the risk that the Fund’s NAV could decrease as a result of investment activities. Investors bear a risk of loss to the extent that the price at which they sell their shares is lower in relation to the Fund’s NAV than at the time of purchase, assuming a stable NAV. Proceeds from the sale of Common Shares in this offering will be reduced by shareholder transaction costs (if applicable, which vary depending on the offering method used). The NAV per Common Share will be reduced by an amount up to the offering costs (estimated to be an additional [-]% of the offering price assuming a Common Share offering price of $[        ] (the Fund’s closing price on the NYSE on [                ])). The NAV per Common Share will be reduced by costs associated with any future offerings of Common Shares. Depending on the premium of Common Shares at the time of any offering of Common Shares hereunder, the Fund’s NAV may be reduced by an amount up to the offering costs. The Common Shares are designed primarily for long-term investors, and you should not view the Fund as a vehicle for trading purposes.

Tax Risk

To qualify for the favorable U.S. federal income tax treatment generally accorded to regulated investment companies, among other things, each Fund must derive in each taxable year at least 90% of its gross income from certain prescribed sources and satisfy a diversification test on a quarterly basis. If a Fund fails to satisfy the qualifying income or diversification requirements in any taxable year, the Fund may be eligible for relief provisions if the failures are due to reasonable cause and not willful neglect and if a penalty tax is paid with respect to each failure to satisfy the applicable requirements.

S-11

Additionally, relief is provided for certain de minimis failures of the diversification requirements where a Fund corrects the failure within a specified period. In order to be eligible for the relief provisions with respect to a failure to meet the diversification requirements, a Fund may be required to dispose of certain assets. If these relief provisions are not available to a Fund and it fails to qualify for treatment as a regulated investment company, all of its taxable income (including its net capital gains) would be subject to federal income tax at regular corporate rates without any deduction for distributions to shareholders, and all distributions from the Fund would be taxable to shareholders as ordinary dividends to the extent of the Fund’s current and accumulated earnings and profits.

Leverage Risk

The use of leverage creates special risks for Common Shareholders, including the likelihood of greater volatility of NAV and market price of, and distributions on, the Common Shares than a comparable portfolio without leverage. The use of leverage in a declining market will likely cause a greater decline in Common Share NAV, which may result in a greater decline of the Common Share price, than if the Fund were not to have used leverage.

Leverage risk is the risk associated with the use of borrowings, the issuance of preferred shares or the use of inverse floating rate securities to leverage the common shares. There can be no assurance that the Fund’s leveraging strategy will be successful. Through the use of leverage, the Fund seeks to enhance potential common share earnings over time by typically sourcing leverage with costs based upon short-term interest rates and investing at long-term municipal rates which are typically, although not always, higher. Because the long-term municipal securities in which the Fund invests generally pay fixed rates of interest while the Fund’s costs of leverage generally fluctuate with short- to intermediate-term yields, the incremental earnings from leverage will vary over time. However, the Fund may use derivatives, such as interest rate swaps, to fix the effective rate paid on all or a portion of the Fund’s leverage in an effort to lower leverage costs over an extended period. Accordingly, the Fund cannot assure you that the use of leverage will result in a higher yield or return to Common Shareholders. The income benefit from leverage will be reduced (increased) to the extent that the difference narrows (widens) between the net earnings on the Fund’s portfolio securities and its cost of leverage. If short- or intermediate-term rates rise and a Fund’s leverage costs fluctuate, the Fund’s cost of leverage could exceed the fixed rate of return on long-term bonds held by the Fund that were acquired during periods of lower interest rates, reducing returns to common shareholders. This could occur even if short- or intermediate-term and long-term municipal rates rise.

The Fund will pay (and Common Shareholders will bear) any costs and expenses relating to the Fund’s use of leverage, which will result in a reduction in the NAV of and net income payable with respect to the Common Shares. Because of the costs of leverage, the Fund may incur losses even if the Fund has positive returns if such returns are not sufficient to cover the costs of leverage.

Nuveen Fund Advisors, based on its assessment of market conditions, may increase or decrease the Fund’s level of leverage or change the types of leverage employed. Such changes may impact the Fund’s distributions and the valuation of the common shares in the secondary market. There can be no assurance that the Fund will continue to utilize leverage or that the Fund’s use of leverage will be successful. Furthermore, the amount of fees paid to Nuveen Fund Advisors and Nuveen Asset Management for investment advisory services will be higher if the Fund uses leverage because the fees will be calculated based on the Fund’s Managed Assets, which may create an incentive for Nuveen Fund Advisors and Nuveen Asset Management to leverage the Fund or increase the Fund’s leverage.

S-12

Certain types of leverage used by the Fund may result in the Fund being subject to certain covenants, asset coverage or other portfolio composition limits by its lenders, Preferred Share purchasers, liquidity providers, rating agencies that may rate the preferred securities, or reverse repurchase counterparties. Such limitations may be more stringent than those imposed by the 1940 Act and may affect whether the Fund is able to maintain its desired amount of leverage. See “Use of Leverage.”

The Fund may invest in the securities of other investment companies, which may themselves be leveraged and therefore present similar risks to those described above. In addition, any investment by the Fund in leveraged investment companies would magnify the Fund’s leverage risk.

S-13

SUMMARY OF FUND EXPENSES

The purpose of the table and the examples below are to help you understand all fees and expenses that you, as a Common Shareholder, would bear directly or indirectly. The table shows the expenses of the Fund as a percentage of the average net assets applicable to Common Shares, and not as a percentage of total assets or Managed Assets.

For a more complete description of the Annual Expenses a common shareholder would bear directly or indirectly, see “Management of the Fund—Investment Management and Sub-Advisory Agreements” in the prospectus.

S-14

Examples

The following examples illustrate the expenses including the applicable transaction fees (referred to as the “Maximum Sales Charge” in the fee table above), if any, and estimated offering costs of $[    ], that a common shareholder would pay on a $1,000 investment that is held for the time periods provided in the table. Each example assumes that all dividends and other distributions are reinvested in the Fund and that the Fund’s Annual Total Expenses, as provided above, remain the same. The examples also assume a 5% annual return.¹

Example # 1 (At-the-Market Transaction)

The following example assumes a transaction fee of 1.00%, as a percentage of the offering price.

Example # 2 (Underwritten Transaction)

The following example assumes a transaction fee of 4.00%, as a percentage of the offering price.

Example # 3 (Privately Negotiated Transaction)

The following example assumes there is no transaction fee.

The examples should not be considered a representation of future expenses. Actual expenses may be greater or less than those shown above.

S-15

The NAV per Common Share, the market price and percentage of premium/(discount) to NAV per Common Share on August 18, 2020 was $22.60, $22.44 and (0.71)%, respectively. As of July 31, 2020, the Fund had 27,367,911 Common Shares outstanding, and net assets applicable to Common Shares of $615,876,616. See “Repurchase of Fund Shares; Conversion to Open-End Fund” in the prospectus.

USE OF PROCEEDS

The net proceeds from the issuance of Common Shares hereunder will be invested in accordance with the Fund’s investment objectives and policies as stated below. Pending investment, the timing of which may vary depending on the size of the investment but in no case is expected to exceed 30 days, it is anticipated that the proceeds will be invested in short-term or long-term securities issued by the U.S. Government and its agencies or instrumentalities or in high quality, short-term money market instruments.

DISTRIBUTIONS

The Fund pays monthly distributions to shareholders. Distributions will be reinvested in additional shares under the Fund’s Dividend Reinvestment Plan unless a shareholder elects to receive cash.

The Fund seeks to pay monthly distributions at a level rate (stated in terms of a fixed cents per common share dividend rate) based on the Fund’s projected performance. The Fund’s ability to maintain a level common share dividend rate will depend on a number of factors. As portfolio and market conditions change, the rate of dividends on the common shares and the Fund’s distribution policy could change. Over time, the Fund will distribute all of its net investment income. In addition, the Fund intends to distribute, at least annually, the taxable ordinary income, if any, to shareholders.

S-16

To permit the Fund to maintain a more stable monthly distribution, the Fund may initially distribute less than the entire amount of net investment income earned in a particular period. Any such undistributed net investment income would be available to supplement future distributions. As a result, the distributions paid by the Fund for any particular monthly period may be more or less than the amount of net investment income actually earned by the Fund during the period.

Undistributed net investment income will be included in the Fund’s net asset value and, correspondingly, distributions from undistributed net investment income will be deducted from the Fund’s net asset value.

As explained more fully below, the Fund may elect to retain rather than distribute all or a portion of any net capital gain (which is the excess of net long-term capital gain over net short-term capital loss) otherwise allocable to common shareholders and pay U.S. federal income tax on the retained gain. As provided under U.S. federal income tax law, common shareholders of record as of the end of the Fund’s taxable year will include their share of the retained net capital gain in their income for the year as a long-term capital gain (regardless of their holding period in the common shares), and will be entitled to an income tax credit or refund for the federal income tax deemed paid on their behalf by the Fund. The Fund may make total distributions during a given calendar year in an amount that exceeds the Fund’s current and accumulated earnings and profits, in which case the excess would be treated by common shareholders as return of capital for federal income tax purposes to the extent of the common shareholder’s basis in his, her or its shares and thereafter as capital gain.

The Fund reserves the right to change its distribution policy and the basis for establishing the rate of its monthly distributions at any time and may do so without prior notice to shareholders.

DIVIDEND REINVESTMENT PLAN

If your common shares are registered directly with the Fund or if you hold your shares with a brokerage firm that participates in the Fund’s Dividend Reinvestment Plan (the “Plan”), your distributions, including any capital gain distributions, will automatically be reinvested in additional shares under the Plan unless you request otherwise. If you elect not to participate in the Plan, or are not eligible to participate because your brokerage firm does not participate in the Plan, you will receive all distributions in cash paid by check mailed directly to you or your brokerage firm by Computershare Trust Company, N.A. and Computershare Inc. (collectively, “Computershare”), as dividend paying agent (the “Plan Agent”). The tax character of distributions (as consisting of ordinary income or capital gain) will be the same regardless of whether such distributions are reinvested or received in cash.

Under the Plan, the number of common shares you will receive will be determined as follows:

(1) If the shares are trading at or above net asset value at the time of valuation, the Fund will issue new shares at a price equal to the greater of (i) net asset value per common share on that date or (ii) 95% of the market price on that date.

(2) If shares are trading below net asset value at the time of valuation, the Plan Agent will receive the dividend or distribution in cash and will purchase shares in the open market, on the NYSE or elsewhere, for the participants’ accounts. It is possible that the market price for the shares may increase before the Plan Agent has completed its purchases. Therefore, the average purchase price per share paid by the Plan Agent may exceed the market price at the time of valuation, resulting in the

S-17

purchase of fewer shares than if the dividend or distribution had been paid in shares issued by the Fund. The Plan Agent will use all dividends and distributions received in cash to purchase shares in the open market within 30 days of the valuation date. Interest will not be paid on any uninvested cash payments. The Plan provides that if shares start trading at or above net asset value before the Plan Agent has completed its purchases, the Plan Agent may cease purchasing shares in the open market, and may invest the uninvested portion in new shares at a price equal to the greater of (i) net asset value per share determined on the last business day immediately prior to the purchase date or (ii) 95% of the market price on that date.

You may withdraw from the Fund’s Plan at any time by giving written or telephonic notice to the Plan Agent. If you withdraw or the Plan is terminated, you will receive whole shares in your account under the Plan and you will receive a cash payment for any fraction of a share in your account. If you wish, the Plan Agent will sell your shares and send you the proceeds, minus brokerage commissions and a $2.50 service fee.

The Fund reserves the right to amend or terminate the Plan if in the judgment of the Board the change is warranted. There is no direct service charge to participants in the Plan; however, the Fund reserves the right to amend the Plan to include a service charge payable by the participants. Additional information about the Plan may be obtained by writing to Computershare, P.O. Box 505000, Louisville, Kentucky 40233-5000.

The Plan Agent maintains all shareholders’ accounts in the Plan and gives confirmation of all transactions in the accounts, including information you may need for tax records. Shares in your account will be held by the Plan Agent in non-certificated form. Any proxy you receive will include all shares you have received under the Plan.

There is no brokerage charge for reinvestment of your dividends or distributions in shares. However, all participants will pay a pro rata share of brokerage commissions incurred by the Plan Agent when it makes open market purchases.

Automatically reinvesting dividends and distributions does not mean that you do not have to pay income taxes due upon receiving dividends and distributions, nor does it mean that you will not realize capital gains or income simply because you are not receiving cash and instead are participating in the Plan.

If you hold your shares with a brokerage firm that does not participate in the Plan or transfer your shares from a participating broker to a non-participating broker, you will not be able to participate in the Plan and any dividend reinvestment may be effected on different terms than those described above. Consult your financial adviser for more information.

S-18

USE OF LEVERAGE

The Fund uses leverage to pursue its investment objectives. The Fund may use leverage to the extent permitted by the 1940 Act. The Fund may source leverage through a number of methods including the issuance of Preferred Shares, investments in inverse floating rate securities, entering into reverse repurchase agreements (effectively a secured borrowing) and borrowings (subject to certain investment restrictions). See “The Fund’s Investments—Portfolio Composition—Municipal Securities—Inverse Floating Rate Securities,” “Risk Factors—Inverse Floating Rate Securities Risk,” “Risk Factors—Reverse Repurchase Agreement Risk” and “Risk Factors—Borrowing Risks” in the prospectus and “Investment Restrictions” in the SAI. The Fund may also use certain derivatives that have the economic effect of leverage by creating additional investment exposure.

Currently, the Fund employs leverage through its use of reverse repurchase agreements. The Fund also currently invests in residual interest certificates of tender option bond trusts, also called inverse floating rate securities, that have the economic effect of leverage because the Fund’s investment exposure to the underlying bonds held by the trust have been effectively financed by the trust’s issuance of floating rate certificates. As of July 31, 2020, the Fund’s leverage through reverse repurchase agreements and through investments in inverse floating rate securities was approximately 36% of its Managed Assets.

To date, the Fund has not issued preferred shares. The Fund may in the future issue certain types of preferred securities to increase the Fund’s leverage.

The Fund may also borrow for temporary purposes permitted by the 1940 Act. The Fund, along with certain other funds managed by Nuveen Fund Advisors (the “Participating Funds”), are party to a committed unsecured credit facility (the “Facility”) provided by a group of lender, under which Participating Funds may borrow for temporary purposes only. Outstanding balances drawn by the Fund, or any other Participating Fund, will bear interest at a variable rate and is the liability of such Fund. The Facility is not intended for sustained levered investment purposes. A large portion of the Facility’s capacity (and corresponding annual costs, excluding interest cost) is currently allocated by Nuveen Fund Advisors to a small number of Participating Funds, which does not include the Fund. The Facility has a 364-day term and will expire in June 2021 unless extended or renewed.

The Fund may reduce or increase leverage based upon changes in market conditions and anticipates that its leverage ratio will vary from time to time based upon variations in the value of the Fund’s holdings. So long as the net rate of income received on the Fund’s investments purchased with leverage proceeds exceeds the then current expense on any leverage, the investment of leverage proceeds will generate more net income than if the Fund had not used leverage. If so, the excess net income will be available to pay higher distributions to common shareholders. However, if the rate of net income received from the Fund’s portfolio investments purchased with leverage is less than the then current expense on outstanding leverage, the Fund may be required to utilize other Fund assets to make expense payments on outstanding leverage, which may result in a decline in Common Share NAV and reduced net investment income available for distribution to common shareholders. See “Risk Factors—Leverage Risk.”

Following an offering of additional Common Shares from time to time, the Fund’s leverage ratio will decrease as a result of the increase in net assets attributable to Common Shares. The Fund’s leverage ratio may decline further to the extent that the net proceeds of an offering of Common Shares

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are used to reduce the Fund’s leverage. A lower leverage ratio may result in lower (higher) returns to common shareholders over a period of time to the extent that net returns on the Fund’s investment portfolio exceed (fall below) its cost of leverage over that period, which lower (higher) returns may impact the level of the Fund’s distributions. See “Risk Factors—Leverage Risk.”

The Fund may use derivatives, such as interest rate swaps with varying terms, in order to manage the interest rate expense associated with all or a portion of its leverage. Interest rate swaps are bi-lateral agreements whereby parties agree to exchange future payments, typically based upon the differential of a fixed rate and a variable rate, on a specified notional amount. Interest rate swaps can enable a Fund to effectively convert its variable leverage expense to fixed, or vice versa. For example, if the Fund issues leverage having a short-term floating rate of interest, the Fund could use interest rate swaps to hedge against a rise in the short-term benchmark interest rates associated with its outstanding leverage. In doing so, the Fund would seek to achieve lower leverage costs, and thereby enhance Common Share distributions, over an extended period, which would be the result if short-term interest rates on average exceed the fixed interest rate over the term of the swap. To the extent the fixed swap rate is greater than short-term market interest rates on average over the period, overall costs associated with leverage will increase (and thereby reduce distributions to common shareholders) than if the Fund had not entered into the interest rate swap(s).

The Fund pays a management fee to Nuveen Fund Advisors (which in turn pays a portion of such fee to Nuveen Asset Management) based on a percentage of Managed Assets. Managed Assets include the proceeds realized and managed from the Fund’s use of most types of leverage (excluding the leverage exposure attributable to the use of futures, swaps and similar derivatives). Because Managed Assets include the Fund’s net assets as well as assets that are attributable to the Fund’s investment of the proceeds of its leverage (including instruments like inverse floating rate securities and reverse repurchase agreements), it is anticipated that the Fund’s Managed Assets will be greater than its net assets. Nuveen Fund Advisors will be responsible for using leverage to pursue the Fund’s investment objective. Nuveen Fund Advisors will base its decision regarding whether and how much leverage to use for the Fund, and the terms of that leverage, on its assessment of whether such use of leverage is in the best interests of the Fund. However, a decision to employ or increase leverage will have the effect, all other things being equal, of increasing Managed Assets, and in turn Nuveen Fund Advisors’ and Nuveen Asset Management’s management fees. Thus, Nuveen Fund Advisors may have a conflict of interest in determining whether to use or increase leverage. Nuveen Fund Advisors will seek to manage that potential conflict by using leverage only when it determines that it would be in the best interests of the Fund and its common shareholders, and by periodically reviewing with the Board of Trustees the Fund’s performance, the Fund’s degree of overall use of leverage and the impact of the use of leverage on that performance.

The 1940 Act generally defines a “senior security” as any bond, debenture, note, or similar obligation or instrument constituting a security and evidencing indebtedness, and any stock of a class having priority over any other class as to distribution of assets or payment of dividends; however, the term does not include any promissory note or other evidence of indebtedness issued in consideration of any loan, extension, or renewal thereof, made for temporary purposes and in an amount not exceeding five percent of the value of the Fund’s total assets. A loan shall be presumed to be for temporary purposes if it is repaid within 60 days and is not extended or renewed.

Under the 1940 Act, the Fund is not permitted to issue “senior securities representing indebtedness” if, immediately after the issuance of such senior securities representing indebtedness, the

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asset coverage ratio with respect to such senior securities would be less than 300%. “Senior securities representing indebtedness” include borrowings (including loans from financial institutions); debt securities; and other derivative investments or transactions such as reverse repurchase agreements and investments in inverse floating rate securities to the extent the Fund has not fully covered, segregated or earmarked cash or liquid assets having a market value at least equal to its future obligation under such instruments. With respect to any such senior securities representing indebtedness, asset coverage means the ratio which the value of the total assets of the Fund, less all liabilities and indebtedness not represented by senior securities (as defined in the 1940 Act), bears to the aggregate amount of such borrowing represented by senior securities representing indebtedness issued by the Fund.

Under the 1940 Act, the Fund is not permitted to issue “senior securities” that are Preferred Shares if, immediately after the issuance of Preferred Shares, the asset coverage ratio with respect to such Preferred Shares would be less than 200%. With respect to any such Preferred Shares, asset coverage means the ratio which the value of the total assets of the Fund, less all liabilities and indebtedness not represented by senior securities, bears to the aggregate amount of senior securities representing indebtedness of the Fund plus the aggregate liquidation preference of such Preferred Shares.

The Fund is limited by certain investment restrictions and may only issue senior securities that are Preferred Shares except the Fund may borrow money from a bank for temporary or emergency purposes or for repurchase of its shares only in an amount not exceeding one-third of the Fund’s total assets (including the amount borrowed) less the Fund’s liabilities (other than borrowings). See “Investment Restrictions” in the SAI. These restrictions are fundamental and may not be changed without the approval of Common Shares and Preferred Shares voting together as a single class.

If the asset coverage with respect to any senior securities issued by the Fund declines below the required ratios discussed above (as a result of market fluctuations or otherwise), the Fund may sell portfolio securities when it may be disadvantageous to do so.

Certain types of leverage used by the Fund may result in the Fund being subject to certain covenants, asset coverage and, or other portfolio composition limits by its lenders, Preferred Share purchasers, rating agencies that may rate Preferred Shares, or reverse repurchase agreement counterparties. Such limitations may be more stringent than those imposed by the 1940 Act and may affect whether the Fund is able to maintain its desired amount of leverage. At this time, Nuveen Fund Advisors does not believe that any such potential investment limitations will impede it from managing the Fund’s portfolio in accordance with its investment objective and policies.

Utilization of leverage is a speculative investment technique and involves certain risks to the common shareholders, including increased variability of the Fund’s net income, distributions and NAV in relation to market changes. See “Risk Factors—Leverage Risk.” There is no assurance that the Fund will use leverage or that the Fund’s use of leverage will work as planned or achieve its goals.

Effects of Leverage

Assuming the utilization of leverage through the combination of reverse repurchase agreements and investments in inverse floating rate securities in the aggregate amount of approximately 37% of the Fund’s Managed Assets, at an aggregate cost of leverage of 1.00%, the income generated by the Fund’s portfolio (net of non-leverage expenses) must exceed 0.37% in order to cover such costs of

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