Item 1 – Report to Stockholders

APRIL 30, 2019

ANNUAL REPORT

BlackRock MuniAssets Fund, Inc. (MUA)

BlackRock MuniEnhanced Fund, Inc. (MEN)

BlackRock MuniHoldings Fund, Inc. (MHD)

BlackRock MuniHoldings Fund II, Inc. (MUH)

BlackRock MuniHoldings Quality Fund, Inc. (MUS)

BlackRock Muni Intermediate Duration Fund, Inc. (MUI)

BlackRock MuniVest Fund II, Inc. (MVT)

Table of Contents

Municipal Market Overview   For the Reporting Period Ended April 30, 2019

Municipal Market Conditions

Municipal bonds experienced solid performance during the period, despite challenged total returns during most of 2018 as interest rates moved higher on the back of continued Fed policy normalization, fiscal stimulus, strong economic growth, and increased U.S. Treasury issuance. Performance turned stronger late in the year, with interest rates rallying as the Fed tilted more dovish and indicated a pivot from forecast based to data driven policy and a wait-and-see approach on future rate hikes. During the period, demand for the asset class remained incredibly firm, although displayed some bouts of volatility. Broadly, investors favored the tax-exempt income, diversification, quality, and value of municipal bonds given that tax reform ultimately lowered the top individual tax rate just 2.6% while eliminating deductions. During the 12 months ended April 30, 2019, municipal bond funds experienced net inflows of approximately $27.8 billion (based on data from the Investment Company Institute).

A Closer Look at Yields

During the same time period, on a relative basis, tax-exempt municipal bonds strongly outperformed U.S. Treasuries, driven by the long end of the yield curve. The relative positive performance of municipal bonds was driven largely by a supply/demand imbalance within the municipal market as investors sought income, incremental yield, and tax shelter in an environment where opportunities became increasingly scarce. The asset class is known for its lower relative volatility and preservation of principal with an emphasis on income as tax rates rise.

Financial Conditions of Municipal Issuers

The majority of municipal credits remain strong, despite well-publicized problems among a few issuers. Four of the five states with the largest amount of debt outstanding — California, New York, Texas and Florida — continue to exhibit improved credit fundamentals. However, several states with the largest unfunded pension liabilities are faced with elevated borrowing costs and difficult budgetary decisions. Across the country on the local level, property values support credit stability. Standard & Poor’s decision to remove its “negative” outlook on New Mexico underscores the improvement in state finances as it was the only remaining state with the designation. Revenue bonds continue to drive performance as investors continue to seek higher yield bonds in the tobacco sector. BlackRock maintains the view that municipal bond defaults will remain minimal and in the periphery while the overall market is fundamentally sound. We continue to advocate careful credit research and believe that a thoughtful approach to structure and security selection remains imperative amid uncertainty in a modestly improving economic environment.

The opinions expressed are those of BlackRock as of April 30, 2019 and are subject to change at any time due to changes in market or economic conditions. The comments should not be construed as a recommendation of any individual holdings or market sectors. Investing involves risk including loss of principal. Bond values fluctuate in price so the value of your investment can go down depending on market conditions. Fixed income risks include interest-rate and credit risk. Typically, when interest rates rise, there is a corresponding decline in bond values. Credit risk refers to the possibility that the bond issuer will not be able to make principal and interest payments. There may be less information on the financial condition of municipal issuers than for public corporations. The market for municipal bonds may be less liquid than for taxable bonds. Some investors may be subject to Alternative Minimum Tax (“AMT”). Capital gains distributions, if any, are taxable.

The Standard & Poor’s Municipal Bond Index, a broad, market value-weighted index, seeks to measure the performance of the U.S. municipal bond market. All bonds in the index are exempt from U.S. federal income taxes or subject to the AMT. Past performance is no guarantee of future results. Index performance is shown for illustrative purposes only. It is not possible to invest directly in an index .

The Benefits and Risks of Leveraging

The Funds may utilize leverage to seek to enhance the distribution rate on, and net asset value (“NAV”) of, their common shares (“Common Shares”). However, there is no guarantee that these objectives can be achieved in all interest rate environments.

In general, the concept of leveraging is based on the premise that the financing cost of leverage, which is based on short-term interest rates, is normally lower than the income earned by a Fund on its longer-term portfolio investments purchased with the proceeds from leverage. To the extent that the total assets of the Funds (including the assets obtained from leverage) are invested in higher-yielding portfolio investments, the Funds’ shareholders benefit from the incremental net income. The interest earned on securities purchased with the proceeds from leverage (after paying the leverage costs) is paid to shareholders in the form of dividends, and the value of these portfolio holdings (less the leverage liability) is reflected in the per share NAV.

To illustrate these concepts, assume a Fund’s Common Shares capitalization is $100 million and it utilizes leverage for an additional $30 million, creating a total value of $130 million available for investment in longer-term income securities. If prevailing short-term interest rates are 3% and longer-term interest rates are 6%, the yield curve has a strongly positive slope. In this case, a Fund’s financing costs on the $30 million of proceeds obtained from leverage are based on the lower short-term interest rates. At the same time, the securities purchased by a Fund with the proceeds from leverage earn income based on longer-term interest rates. In this case, a Fund’s financing cost of leverage is significantly lower than the income earned on a Fund’s longer-term investments acquired from such leverage proceeds, and therefore the holders of Common Shares (“Common Shareholders”) are the beneficiaries of the incremental net income.

However, in order to benefit Common Shareholders, the return on assets purchased with leverage proceeds must exceed the ongoing costs associated with the leverage. If interest and other costs of leverage exceed the Funds’ return on assets purchased with leverage proceeds, income to shareholders is lower than if the Funds had not used leverage. Furthermore, the value of the Funds’ portfolio investments generally varies inversely with the direction of long-term interest rates, although other factors can influence the value of portfolio investments. In contrast, the amount of the Funds’ obligations under their respective leverage arrangements generally does not fluctuate in relation to interest rates. As a result, changes in interest rates can influence the Funds’ NAVs positively or negatively. Changes in the future direction of interest rates are very difficult to predict accurately, and there is no assurance that the Funds’ intended leveraging strategy will be successful.

The use of leverage also generally causes greater changes in each Fund’s NAV, market price and dividend rates than comparable portfolios without leverage. In a declining market, leverage is likely to cause a greater decline in the NAV and market price of a Fund’s Common Shares than if the Fund were not leveraged. In addition, each Fund may be required to sell portfolio securities at inopportune times or at distressed values in order to comply with regulatory requirements applicable to the use of leverage or as required by the terms of leverage instruments, which may cause the Fund to incur losses. The use of leverage may limit a Fund’s ability to invest in certain types of securities or use certain types of hedging strategies. Each Fund incurs expenses in connection with the use of leverage, all of which are borne by Common Shareholders and may reduce income to the Common Shares. Moreover, to the extent the calculation of the Funds’ investment advisory fees includes assets purchased with the proceeds of leverage, the investment advisory fees payable to the Funds’ investment adviser will be higher than if the Funds did not use leverage.

To obtain leverage, each Fund has issued Variable Rate Demand Preferred Shares (“VRDP Shares”) or Variable Rate Muni Term Preferred Shares (“VMTP Shares”) (collectively, “Preferred Shares”) and/or leveraged its assets through the use of tender option bond trusts (“TOB Trusts”) as described in the Notes to Financial Statements.

Under the Investment Company Act of 1940, as amended (the “1940 Act”), each Fund is permitted to issue debt up to 33 1/3% of its total managed assets or equity securities (e.g., Preferred Shares) up to 50% of its total managed assets. A Fund may voluntarily elect to limit its leverage to less than the maximum amount permitted under the 1940 Act. In addition, a Fund may also be subject to certain asset coverage, leverage or portfolio composition requirements imposed by the Preferred Shares’ governing instruments or by agencies rating the Preferred Shares, which may be more stringent than those imposed by the 1940 Act.

If a Fund segregates or designates on its books and records cash or liquid assets having a value not less than the value of a Fund’s obligations under the TOB Trust (including accrued interest), then the TOB Trust is not considered a senior security and is not subject to the foregoing limitations and requirements imposed by the 1940 Act.

Derivative Financial Instruments

The Funds may invest in various derivative financial instruments. These instruments are used to obtain exposure to a security, commodity, index, market, and/or other assets without owning or taking physical custody of securities, commodities and/or other referenced assets or to manage market, equity, credit, interest rate, foreign currency exchange rate, commodity and/or other risks. Derivative financial instruments may give rise to a form of economic leverage and involve risks, including the imperfect correlation between the value of a derivative financial instrument and the underlying asset, possible default of the counterparty to the transaction or illiquidity of the instrument. The Funds’ successful use of a derivative financial instrument depends on the investment adviser’s ability to predict pertinent market movements accurately, which cannot be assured. The use of these instruments may result in losses greater than if they had not been used, may limit the amount of appreciation a Fund can realize on an investment and/or may result in lower distributions paid to shareholders. The Funds’ investments in these instruments, if any, are discussed in detail in the Notes to Financial Statements.

Investment Objective

BlackRock MuniAssets Fund, Inc.’s (MUA) (the “Fund”) investment objective is to provide high current income exempt from U.S. federal income taxes by investing primarily in a portfolio of medium- to lower-grade or unrated municipal obligations, the interest on which, in the opinion of bond counsel to the issuer, is exempt from U.S. federal income taxes. The Fund seeks to achieve its investment objective by investing, under normal market conditions, at least 80% of its assets in municipal bonds exempt from U.S. federal income taxes (except that the interest may be subject to the U.S. federal alternative minimum tax). The Fund invests at least 65% of its assets in municipal bonds that are rated in the medium to lower rating categories by nationally recognized rating services (for example, Baa or lower by Moody’s Investors Service, Inc. (“Moody’s”) or BBB or lower by S&P Global (“S&P”), or securities that are unrated but are deemed by the investment adviser to be of comparable quality at the time of investment. The Fund may invest directly in such securities or synthetically through the use of derivatives.

No assurance can be given that the Fund’s investment objective will be achieved.

Fund Information

Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles.

Past performance is not indicative of future results.

The following discussion relates to the Fund’s absolute performance based on NAV:

After performing poorly through the end of October, municipal bonds recovered to post a positive total return for the full 12-month period. The initial weakness was largely brought about by concerns that the Fed would raise interest rates aggressively in 2019. However, subsequent signs of slowing growth prompted investors to adjust their expectations in favor of a more accommodative Fed policy, sparking a rally across the bond market from early November onward. Volatility in equities and uncertainty surrounding U.S. trade policy also helped fuel a “flight to quality” into the fixed-income markets.

Long-dated securities on the lower end of the investment grade spectrum (those rated BBB or unrated) were the largest contributors to performance. At the sector level, holdings in health care, transportation and tobacco issues were key contributors. The Fund’s holdings in Puerto Rico also aided results.

The Fund actively sought to manage interest rate risk using U.S. Treasury futures. Since U.S. Treasury yields fell, as price rose, this strategy had a small, negative effect on returns.

The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results.

Market Price and Net Asset Value History For the Past Five Years