AUGUST 31, 2020

BlackRock Municipal Bond Trust (BBK)

BlackRock Municipal Income Investment Quality Trust (BAF)

BlackRock Municipal Income Quality Trust (BYM)

BlackRock Municipal Income Trust II (BLE)

BlackRock MuniHoldings Investment Quality Fund (MFL)

BlackRock MuniVest Fund, Inc. (MVF)

Supplemental Information  (unaudited)

Section 19(a) Notices

BlackRock MuniVest Fund, Inc.’s (MVF) (the “Trust”) amounts and sources of distributions reported are estimates and are being provided pursuant to regulatory requirements and are not being provided for tax reporting purposes. The actual amounts and sources for tax reporting purposes will depend upon the Trust’s investment experience during the year and may be subject to changes based on tax regulations. Shareholders will receive a Form 1099-DIV each calendar year that will inform them how to report these distributions for federal income tax purposes.

August 31, 2020

Section 19(a) notices for the Trust, as applicable, are available on the BlackRock website at blackrock.com.

Table of Contents

Municipal Market Overview  For the Reporting Period Ended August 31, 2020

Municipal Market Conditions

Municipal bonds posted positive total returns during the period amid increased volatility. Early in the period, strong performance was driven by a favorable technical backdrop. However, as the economy shut down as a result of the COVID-19 pandemic, the municipal market experienced volatility that was worse than during the height of the global financial crisis. Performance plummeted -10.87% during a two-week period in March, before rebounding on valuation-based buying. (For comparison, the -11.86% correction in 2008 spanned more than a month.) As federal authorities stepped in to provide stimulus, passing the CARES Act and creating the Municipal Lending Facility, the market stabilized. Strong performance returned alongside the re-opening of the economy but stalled in August as Congress failed to pass additional fiscal aide.

the months of March and April (based on data from the Investment Company Institute). For the same 12-month period, new issuance was robust at $452 billion but slowed during the height of pandemic as market liquidity became constrained amid the flight to quality. Taxable municipal issuance was elevated as issuers increasingly advance refunded tax-exempt debt in the taxable municipal market for cost savings.

Financial Conditions of Municipal Issuers

The COVID-19 pandemic is an unprecedented shock to the system impacting nearly every sector in the municipal market. Luckily, most states and municipalities were in excellent fiscal health before the crisis and the federal government has provided an incredible amount of support. BlackRock expects ongoing stability in high-quality states as well as school districts and local governments given that property taxes have proven resilient in past economic downturns. Essential public services such as power, water, and sewer are protected segments. State housing authority bonds, flagship universities, and strong national and regional health systems are well positioned to absorb the impact of the economic shock. However, some segments are facing daunting financial challenges and additional federal support may not materialize, requiring issuers to draw down reserves, raise user fees / taxes, slash expenditures, and/or borrow to meet financial obligations. Critical providers (safety net hospitals, mass transit systems, airports) with limited resources will require funding from the states and broader municipalities they serve. BlackRock anticipates that a small subset of the market, mainly non-rated stand-alone projects, will experience significant credit deterioration. Assuming the worst case, a prolonged recession would likely mean a spate of defaults, primarily in non-rated credits, and the migration of the municipal market’s overall credit quality from double-A to a still-strong single-A rating. As a result, BlackRock advocates careful credit selection and anticipate increased credit dispersion as the market navigates near-term uncertainty.

The opinions expressed are those of BlackRock as of August 31, 2020 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 S&P 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 not an indication 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 Trusts 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 Trust on its longer-term portfolio investments purchased with the proceeds from leverage. To the extent that the total assets of each Trust (including the assets obtained from leverage) are invested in higher-yielding portfolio investments, each Trust’s 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 Trust’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 Trust’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 Trust with the proceeds from leverage earn income based on longer-term interest rates. In this case, a Trust’s financing cost of leverage is significantly lower than the income earned on a Trust’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 each Trust’s return on assets purchased with leverage proceeds, income to shareholders is lower than if the Trust had not used leverage. Furthermore, the value of each Trust’s 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 value of a Trust’s obligations under its respective leverage arrangement generally does not fluctuate in relation to interest rates. As a result, changes in interest rates can influence each Trust’s NAV positively or negatively. Changes in the future direction of interest rates are very difficult to predict accurately, and there is no assurance that each Trust’s intended leveraging strategy will be successful.

The use of leverage also generally causes greater changes in each Trust’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 Trust’s Common Shares than if the Trust were not leveraged. In addition, each Trust 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 Trust to incur losses. The use of leverage may limit a Trust’s ability to invest in certain types of securities or use certain types of hedging strategies. Each Trust 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 each Trust’s investment advisory fees includes assets purchased with the proceeds of leverage, the investment advisory fees payable to each Trust’s investment adviser will be higher than if the Trusts did not use leverage.

To obtain leverage, each Trust 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 Trust 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 Trust may voluntarily elect to limit its leverage to less than the maximum amount permitted under the 1940 Act.

In addition, a Trust 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 Trust segregates or designates on its books and records cash or liquid assets having a value not less than the value of a Trust’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 Trusts 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 Trusts’ 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 Trust can realize on an investment and/or may result in lower distributions paid to shareholders. The Trusts’ investments in these instruments, if any, are discussed in detail in the Notes to Financial Statements.

Investment Objective

BlackRock Municipal Bond Trust’s (BBK) (the “Trust”) investment objective is to provide current income exempt from regular U.S. federal income tax. The Trust seeks to achieve its investment objective by investing primarily in municipal bonds exempt from regular U.S. federal income taxes (except that the interest may be subject to the U.S. federal alternative minimum tax). The Trust invests, under normal market conditions, at least 80% of its managed assets in municipal bonds that are investment grade quality or, if unrated, determined to be of comparable quality by the investment adviser at the time of investment. The Trust may invest directly in securities or synthetically through the use of derivatives.

On June 16, 2020, the Board of Trustees of BBK and the Board of Directors of BlackRock MuniHoldings Fund, Inc. (MHD) each approved the reorganization of BBK into MHD. Subject to approvals by each Trust’s shareholders and the satisfaction of customary closing conditions, the reorganization is expected to occur during the first quarter of 2021.

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

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

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

Past performance is not an indication of future results.

More information about the Trust’s historical performance can be found in the “Closed End Funds” section of blackrock.com.

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

Municipal bonds performed well from the beginning of the reporting period until February 2020 due to accommodative Fed policy and favorable supply-and-demand trends in the market. This supportive backdrop changed abruptly in March once the spread of COVID-19 led to travel restrictions, business closures and stay-at-home orders, causing significant, broad-based weakness across the financial markets. Tax-exempt issues were hard hit in the sell-off, as investors withdrew cash from municipal bond funds and low market liquidity inhibited efficient pricing. Municipal bonds recovered in the April-August interval due to aggressive stimulus from the Fed and U.S. Congress, allowing the category to finish in positive territory for the full period.

The Trust’s use of leverage helped results by augmenting income and amplifying the effect of rising prices. The Trust’s positions in bonds with maturities of 20 years and above also contributed to performance. Long-term bonds benefited from their higher interest rate sensitivity given that yields fell significantly. (Prices rise as yields fall.) Holdings in the state tax-backed, school district and tobacco sectors further contributed to results.

The Trust actively sought to manage interest rate risk using U.S. Treasury futures. Since U.S. Treasury yields fell, as prices rose, this strategy had an adverse impact on performance. The Trust did not hold any U.S. Treasury futures as of August 31, 2020. Select holdings in the high yield category (bonds rated BBB and below, as well as non-rated issues), modestly detracted from performance due to pandemic-related concerns. Student housing debt, in particular, was hurt by the effects of COVID-19. In addition, high yield bonds tied to future revenue projections generally lagged.

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.