Principal Risks of Investing in the Fund

Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The following is a summary description of the principal risks of investing in the Fund.

Interest Rate Risk — The market value of bonds and other fixed-income securities changes in response to interest rate changes and other factors. Interest rate risk is the risk that prices of bonds and other fixed-income securities will increase as interest rates fall and decrease as interest rates rise.

The Fund may be subject to a greater risk of rising interest rates due to the current period of historically low rates. For example, if interest rates increase by 1%, assuming a current portfolio duration of ten years, and all other factors being equal, the value of the Fund’s investments would be expected to decrease by 10%. The magnitude of these fluctuations in the market price of bonds and other fixed-income securities is generally greater for those securities with longer maturities. Fluctuations in the market price of the Fund’s investments will not affect interest income derived from instruments already owned by the Fund, but will be reflected in the Fund’s net asset value. The Fund may lose money if short-term or long-term interest rates rise sharply in a manner not anticipated by Fund management.

To the extent the Fund invests in debt securities that may be prepaid at the option of the obligor (such as mortgage-backed securities), the sensitivity of such securities to changes in interest rates may increase (to the detriment of the Fund) when interest rates rise. Moreover, because rates on certain floating rate debt securities typically reset only periodically, changes in prevailing interest rates (and particularly sudden and significant changes) can be expected to cause some fluctuations in the net asset value of the Fund to the extent that it invests in floating rate debt securities.

These basic principles of bond prices also apply to U.S. Government securities. A security backed by the “full faith and credit” of the U.S. Government is guaranteed only as to its stated interest rate and face value at maturity, not its current market price. Just like other fixed-income securities, government-guaranteed securities will fluctuate in value when interest rates change.

A general rise in interest rates has the potential to cause investors to move out of fixed-income securities on a large scale, which may increase redemptions from funds that hold large amounts of fixed-income securities. Heavy redemptions could cause the Fund to sell assets at inopportune times or at a loss or depressed value and could hurt the Fund’s performance.

Credit Risk — Credit risk refers to the possibility that the issuer of a debt security (i.e., the borrower) will not be able to make payments of interest and principal when due. Changes in an issuer’s credit rating or the market’s perception of an issuer’s creditworthiness may also affect the value of the Fund’s investment in that issuer. The degree of credit risk depends on both the financial condition of the issuer and the terms of the obligation.

Extension Risk — When interest rates rise, certain obligations will be paid off by the obligor more slowly than anticipated, causing the value of these obligations to fall.

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Prepayment Risk — When interest rates fall, certain obligations will be paid off by the obligor more quickly than originally anticipated, and the Fund may have to invest the proceeds in securities with lower yields.

Volatility Risk — Volatility is defined as the characteristic of a security, an index or a market to fluctuate significantly in price within a short time period. A risk of the Fund’s use of derivatives is that the fluctuations in their values may not correlate with the overall securities markets.

Counterparty Risk — Derivatives are also subject to counterparty risk, which is the risk that the other party in the transaction will not fulfill its contractual obligation.

Market and Liquidity Risk — The possible lack of a liquid secondary market for derivatives and the resulting inability of the Fund to sell or otherwise close a derivatives position could expose the Fund to losses and could make derivatives more difficult for the Fund to value accurately.

Valuation Risk — Valuation may be more difficult in times of market turmoil since many investors and market makers may be reluctant to purchase complex instruments or quote prices for them.

Hedging Risk — Hedges are sometimes subject to imperfect matching between the derivative and the underlying security, and there can be no assurance that the Fund’s hedging transactions will be effective. The use of hedging may result in certain adverse tax consequences.

Tax Risk — Certain aspects of the tax treatment of derivative instruments, including swap agreements and commodity-linked derivative instruments, are currently unclear and may be affected by changes in legislation, regulations or other legally binding authority. Such treatment may be less favorable than that given to a direct investment in an underlying asset and may adversely affect the timing, character and amount of income the Fund realizes from its investments.

Regulatory Risk — Derivative contracts, including, without limitation, swaps, currency forwards and non-deliverable forwards, are subject to regulation under the Dodd-Frank Wall Street Reform and Consumer Protection Act (“Dodd-Frank Act”) in the United States and under comparable regimes in Europe, Asia and other non-U.S. jurisdictions. Under the Dodd-Frank Act, certain derivatives are subject to margin requirements and swap dealers are required to collect margin from the Fund with respect to such derivatives. Specifically, regulations are now in effect that require swap dealers to post and collect variation margin (comprised of specified liquid instruments and subject to a required haircut) in connection with trading of over-the-counter (“OTC”) swaps with the Fund. Shares of investment companies (other than certain money market funds) may not be posted as collateral under these regulations. Requirements for posting of initial margin in connection with OTC swaps will be phased-in through 2020. In addition, regulations adopted by prudential regulators that will begin to take effect in 2019 will require certain bank-regulated counterparties and certain of their affiliates to include in certain financial contracts, including many derivatives contracts, terms that delay or restrict the rights of counterparties, such as the Fund, to terminate such contracts, foreclose upon collateral, exercise other default rights or restrict transfers of credit support in the event that the counterparty and/or its affiliates are subject to certain types of resolution or insolvency proceedings. The implementation of these requirements with respect to derivatives, as well as regulations under the Dodd-Frank Act regarding clearing, mandatory trading and margining of other derivatives, may increase the costs and risks to the Fund of trading in these instruments and, as a result, may affect returns to investors in the Fund.

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The securities of other investment companies and ETFs in which the Fund may invest may be leveraged. As a result, the Fund may be indirectly exposed to leverage through an investment in such securities. An investment in securities of other investment companies and ETFs that use leverage 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 (and, indirectly, the long-term returns of shares of the Fund) will be diminished.

As with other investments, investments in other investment companies, including ETFs, are subject to market and selection risk. To the extent the Fund is held by an affiliated fund, the ability of the Fund itself to hold other investment companies may be limited.

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Investment Risks

This section contains a discussion of the general risks of investing in the Fund. The “Investment Objective and Policies” section in the Statement of Additional Information (the “SAI”) also includes more information about the Fund, its investments and the related risks. As with any fund, there can be no guarantee that the Fund will meet its investment objective or that the Fund’s performance will be positive for any period of time. An investment in the Fund is not a deposit in any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or by any bank or governmental agency.

Principal Risks of Investing in the Fund

The market for corporate loans may be subject to irregular trading activity and wide bid/ask spreads.

The corporate loans in which the Fund invests are subject to the risk of loss of principal and income. Although borrowers frequently provide collateral to secure repayment of these obligations they do not always do so. If they do provide collateral, the value of the collateral may not completely cover the borrower’s obligations at the time of a default. If a borrower files for protection from its creditors under the U.S. bankruptcy laws, these laws may limit the Fund’s rights to its collateral. In addition, the value of collateral may erode during a bankruptcy case. In the event of a bankruptcy, the holder of a corporate loan may not recover its principal, may experience a long delay in recovering its investment and may not receive interest during the delay.

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Interest Rate Risk — The market value of bonds and other fixed-income securities changes in response to interest rate changes and other factors. Interest rate risk is the risk that prices of bonds and other fixed-income securities will increase as interest rates fall and decrease as interest rates rise. The Fund may be subject to a greater risk of rising interest rates due to the current period of historically low rates. For example, if interest rates increase by 1%, assuming a current portfolio duration of ten years, and all other factors being equal, the value of the Fund’s investments would be expected to decrease by 10%. The magnitude of these fluctuations in the market price of bonds and other fixed-income securities is generally greater for those securities with longer maturities. Fluctuations in the market price of the Fund’s investments will not affect interest income derived from instruments already owned by the Fund, but will be reflected in the Fund’s net asset value. The Fund may lose money if short-term or long-term interest rates rise sharply in a manner not anticipated by Fund management. To the extent the Fund invests in debt securities that may be prepaid at the option of the obligor (such as mortgage-backed securities), the sensitivity of such securities to changes in interest rates may increase (to the detriment of the Fund) when interest rates rise. Moreover, because rates on certain floating rate debt securities typically reset only periodically, changes in prevailing interest rates (and particularly sudden and significant changes) can be expected to cause some fluctuations in the net asset value of the Fund to the extent that it invests in floating rate debt securities. These basic principles of bond prices also apply to U.S. Government securities. A security backed by the “full faith and credit” of the U.S. Government is guaranteed only as to its stated interest rate and face value at maturity, not its current market price. Just like other fixed-income securities, government-guaranteed securities will fluctuate in value when interest rates change.

Following the financial crisis that began in 2007, the Federal Reserve has attempted to stabilize the economy and support the economic recovery by keeping the federal funds rate (the interest rate at which depository institutions lend reserve balances to other depository institutions overnight) at or near zero percent. In addition, as part of its monetary stimulus program known as quantitative easing, the Federal Reserve has purchased on the open market large quantities of securities issued or guaranteed by the U.S. Government, its agencies or instrumentalities. As the Federal Reserve “tapers” or reduces the amount of securities it purchases pursuant to quantitative easing, and/or if the Federal Reserve raises the federal funds rate, there is a risk that interest rates will rise. A general rise in interest rates has the potential to cause investors to move out of fixed-income securities on a large scale, which may increase redemptions from mutual funds that hold large amounts of fixed-income securities. Heavy redemptions could cause the Fund to sell assets at inopportune times or at a loss or depressed value and could hurt the Fund’s performance.

During periods of very low or negative interest rates, the Fund may be unable to maintain positive returns. Certain countries have recently experienced negative interest rates on certain fixed-income instruments. Very low or negative interest rates may magnify interest rate risk. Changing interest rates, including rates that fall below zero, may have unpredictable effects on markets, may result in heightened market volatility and may detract from Fund performance to the extent the Fund is exposed to such interest rates.

Credit Risk — Credit risk refers to the possibility that the issuer of a debt security (i.e., the borrower) will not be able to make payments of interest and principal when due. Changes in an issuer’s credit rating or the market’s perception of an issuer’s creditworthiness may also affect the value of the Fund’s investment in that issuer. The degree of credit risk depends on both the financial condition of the issuer and the terms of the obligation.

Extension Risk — When interest rates rise, certain obligations will be paid off by the obligor more slowly than anticipated, causing the value of these obligations to fall. Rising interest rates tend to extend the duration of securities, making them more sensitive to changes in interest rates. The value of longer-term securities generally changes more in response to changes in interest rates than shorter-term securities. As a result, in a period of rising interest rates, securities may exhibit additional volatility and may lose value.

Prepayment Risk — When interest rates fall, certain obligations will be paid off by the obligor more quickly than originally anticipated, and the Fund may have to invest the proceeds in securities with lower yields. In periods of falling interest rates, the rate of prepayments tends to increase (as does price fluctuation) as borrowers are motivated to pay off debt and refinance at new lower rates. During such periods, reinvestment of the prepayment proceeds by the management team will generally be at lower rates of return than the return on the assets that were prepaid. Prepayment reduces the yield to maturity and the average life of the security.

Volatility Risk — The Fund’s use of derivatives may reduce the Fund’s returns and/or increase volatility. Volatility is defined as the characteristic of a security, an index or a market to fluctuate significantly in price within a short time period. A risk of the Fund’s use of derivatives is that the fluctuations in their values may not correlate with the overall securities markets.

Counterparty Risk — Derivatives are also subject to counterparty risk, which is the risk that the other party in the transaction will not fulfill its contractual obligation.

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Market and Liquidity Risk — Some derivatives are more sensitive to interest rate changes and market price fluctuations than other securities. The possible lack of a liquid secondary market for derivatives and the resulting inability of the Fund to sell or otherwise close a derivatives position could expose the Fund to losses and could make derivatives more difficult for the Fund to value accurately. The Fund could also suffer losses related to its derivatives positions as a result of unanticipated market movements, which losses are potentially unlimited. Finally, BlackRock may not be able to predict correctly the direction of securities prices, interest rates and other economic factors, which could cause the Fund’s derivatives positions to lose value.

Valuation Risk  — Valuation may be more difficult in times of market turmoil since many investors and market makers may be reluctant to purchase complex instruments or quote prices for them. Derivatives may also expose the Fund to greater risk and increase its costs. Certain transactions in derivatives involve substantial leverage risk and may expose the Fund to potential losses that exceed the amount originally invested by the Fund.

Hedging Risk — When a derivative is used as a hedge against a position that the Fund holds, any loss generated by the derivative generally should be substantially offset by gains on the hedged investment, and vice versa. While hedging can reduce or eliminate losses, it can also reduce or eliminate gains. Hedges are sometimes subject to imperfect matching between the derivative and the underlying security, and there can be no assurance that the Fund’s hedging transactions will be effective. The use of hedging may result in certain adverse tax consequences noted below.

Tax Risk — The federal income tax treatment of a derivative may not be as favorable as a direct investment in an underlying asset and may adversely affect the timing, character and amount of income the Fund realizes from its investments. As a result, a larger portion of the Fund’s distributions may be treated as ordinary income rather than capital gains. In addition, certain derivatives are subject to mark-to-market or straddle provisions of the Internal Revenue Code of 1986, as amended (the “Internal Revenue Code”). If such provisions are applicable, there could be an increase (or decrease) in the amount of taxable dividends paid by the Fund. In addition, the tax treatment of certain derivatives, such as swaps, is unsettled and may be subject to future legislation, regulation or administrative pronouncements issued by the Internal Revenue Service (the “IRS”).

Regulatory Risk — Derivative contracts, including, without limitation, swaps, currency forwards and non-deliverable forwards, are subject to regulation under the Dodd-Frank Wall Street Reform and Consumer Protection Act (“Dodd-Frank Act”) in the United States and under comparable regimes in Europe, Asia and other non-U.S. jurisdictions. Under the Dodd-Frank Act, certain derivatives are subject to margin requirements and swap dealers are required to collect margin from the Fund with respect to such derivatives. Specifically, regulations are now in effect that require swap dealers to post and collect variation margin (comprised of specified liquid instruments and subject to a required haircut) in connection with trading of over-the-counter (“OTC”) swaps with the Fund. Shares of investment companies (other than certain money market funds) may not be posted as collateral under these regulations. Requirements for posting of initial margin in connection with OTC swaps will be phased-in through 2020. In addition, regulations adopted by prudential regulators that will begin to take effect in 2019 will require certain bank-regulated counterparties and certain of their affiliates to include in certain financial contracts, including many derivatives contracts, terms that delay or restrict the rights of counterparties, such as the Fund, to terminate such contracts, foreclose upon collateral, exercise other default rights or restrict transfers of credit support in the event that the counterparty and/or its affiliates are subject to certain types of resolution or insolvency proceedings. The implementation of these requirements with respect to derivatives, as well as regulations under the Dodd-Frank Act regarding clearing, mandatory trading and margining of other derivatives, may increase the costs and risks to the Fund of trading in these instruments and, as a result, may affect returns to investors in the Fund.

Future regulatory developments may impact the Fund’s ability to invest or remain invested in certain derivatives. Legislation or regulation may also change the way in which the Fund itself is regulated. BlackRock cannot predict the effects of any new governmental regulation that may be implemented on the ability of the Fund to use swaps or any other financial derivative product, and there can be no assurance that any new governmental regulation will not adversely affect the Fund’s ability to achieve its investment objective.

Risks Specific to Certain Derivatives Used by the Fund

Swaps – Swap agreements, including total return swaps that may be referred to as contracts for difference, are two-party contracts entered into for periods ranging from a few weeks to more than one year. In a standard “swap” transaction, two parties agree to exchange the returns (or differentials in rates of return) earned or realized on particular predetermined investments or instruments, which can be adjusted for an interest factor. Swap agreements involve the risk that the party with whom the Fund has entered into the swap will default on its obligation to pay the Fund and the risk that the Fund will not be able to meet its obligations to pay the other party to the agreement. Swap agreements may also involve the risk that there is an imperfect correlation between the return on the Fund’s obligation to its counterparty and the return on referenced asset. In addition, swap agreements are subject to market and liquidity risk, leverage risk and hedging risk.

Credit Default Swaps – Credit default swaps and related instruments, such as credit default swap index products, may involve greater risks than if the Fund invested in the reference obligation directly. These instruments may have as reference obligations one or more securities that are not currently held by the Fund. The protection

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“buyer” may be obligated to pay the protection “seller” an up-front payment or a periodic stream of payments over the term of the contract, provided generally that no credit event on a reference obligation has occurred. Credit default swaps and related instruments involve special risks in addition to those mentioned above because they are difficult to value, are highly susceptible to liquidity and credit risk, and generally pay a return to the party that has paid the premium only in the event of an actual default by the issuer of the underlying obligation (as opposed to a credit downgrade or other indication of financial difficulty).

Forward Foreign Currency Exchange Contracts – Forward foreign currency exchange transactions are OTC contracts to purchase or sell a specified amount of a specified currency or multinational currency unit at a price and future date set at the time of the contract. Forward foreign currency exchange contracts do not eliminate fluctuations in the value of non-U.S. securities but rather allow the Fund to establish a fixed rate of exchange for a future point in time. This strategy can have the effect of reducing returns and minimizing opportunities for gain.

Indexed and Inverse Securities – Indexed and inverse securities provide a potential return based on a particular index of value or interest rates. The Fund’s return on these securities will be subject to risk with respect to the value of the particular index. These securities are subject to leverage risk and correlation risk. Certain indexed and inverse securities have greater sensitivity to changes in interest rates or index levels than other securities, and the Fund’s investment in such instruments may decline significantly in value if interest rates or index levels move in a way Fund management does not anticipate.

Futures – Futures are standardized, exchange-traded contracts that obligate a purchaser to take delivery, and a seller to make delivery, of a specific amount of an asset at a specified future date at a specified price. The primary risks associated with the use of futures contracts and options are: (a) the imperfect correlation between the change in market value of the instruments held by the Fund and the price of the futures contract or option; (b) the possible lack of a liquid secondary market for a futures contract and the resulting inability to close a futures contract when desired; (c) losses caused by unanticipated market movements, which are potentially unlimited; (d) the investment adviser’s inability to predict correctly the direction of securities prices, interest rates, currency exchange rates and other economic factors; and (e) the possibility that the counterparty will default in the performance of its obligations.

Options – An option is an agreement that, for a premium payment or fee, gives the option holder (the purchaser) the right but not the obligation to buy (a “call option”) or sell (a “put option”) the underlying asset (or settle for cash in an amount based on an underlying asset, rate, or index) at a specified price (the “exercise price”) during a period of time or on a specified date. Investments in options are considered speculative. When the Fund purchases an option, it may lose the total premium paid for it if the price of the underlying security or other assets decreased, remained the same or failed to increase to a level at or beyond the exercise price (in the case of a call option) or increased, remained the same or failed to decrease to a level at or below the exercise price (in the case of a put option). If a put or call option purchased by the Fund were permitted to expire without being sold or exercised, its premium would represent a loss to the Fund. To the extent that the Fund writes or sells an option, if the decline or increase in the underlying asset is significantly below or above the exercise price of the written option, the Fund could experience a substantial loss.

Many emerging markets have histories of political instability and abrupt changes in policies. As a result, their governments are more likely to take actions that are hostile or detrimental to private enterprise or foreign investment than those of more developed countries, including expropriation of assets, confiscatory taxation, high rates of inflation or unfavorable diplomatic developments. In the past, governments of such nations have expropriated substantial amounts of private property, and most claims of the property owners have never been fully settled. There is no assurance that such expropriations will not reoccur. In such an event, it is possible that the Fund could lose the entire value of its investments in the affected market. Some countries have pervasive corruption and crime that may hinder investments. Certain emerging markets may also face other significant internal or external risks, including the risk of war, and ethnic, religious and racial conflicts. In addition, governments in many emerging market countries participate to a significant degree in their economies and securities markets,

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which may impair investment and economic growth. National policies that may limit the Fund’s investment opportunities include restrictions on investment in issuers or industries deemed sensitive to national interests.

Emerging markets may also have differing legal systems and the existence or possible imposition of exchange controls, custodial restrictions or other foreign or U.S. governmental laws or restrictions applicable to such investments. Sometimes, they may lack or be in the relatively early development of legal structures governing private and foreign investments and private property. Many emerging markets do not have income tax treaties with the United States, and as a result, investments by the Fund may be subject to higher withholding taxes in such countries. In addition, some countries with emerging markets may impose differential capital gains taxes on foreign investors.

Practices in relation to settlement of securities transactions in emerging markets involve higher risks than those in developed markets, in part because the Fund will need to use brokers and counterparties that are less well capitalized, and custody and registration of assets in some countries may be unreliable. The possibility of fraud, negligence, undue influence being exerted by the issuer or refusal to recognize ownership exists in some emerging markets, and, along with other factors, could result in ownership registration being completely lost. The Fund would absorb any loss resulting from such registration problems and may have no successful claim for compensation. In addition, communications between the United States and emerging market countries may be unreliable, increasing the risk of delayed settlements or losses of security certificates.

Certain Risks of Holding Fund Assets Outside the United States — The Fund generally holds its foreign securities and cash in foreign banks and securities depositories. Some foreign banks and securities depositories may be recently organized or new to the foreign custody business. In addition, there may be limited or no regulatory oversight of their operations. Also, the laws of certain countries limit the Fund’s ability to recover its assets if a foreign bank, depository or issuer of a security, or any of their agents, goes bankrupt. In addition, it is often more expensive for the Fund to buy, sell and hold securities in certain foreign markets than in the United States. The increased expense of investing in foreign markets reduces the amount the Fund can earn on its investments and typically results in a higher operating expense ratio for the Fund than for investment companies invested only in the United States.

Currency Risk — Securities and other instruments in which the Fund invests may be denominated or quoted in currencies other than the U.S. dollar. For this reason, changes in foreign currency exchange rates can affect the value of the Fund’s portfolio.

Generally, when the U.S. dollar rises in value against a foreign currency, a security denominated in that currency loses value because the currency is worth fewer U.S. dollars. Conversely, when the U.S. dollar decreases in value against a foreign currency, a security denominated in that currency gains value because the currency is worth more U.S. dollars. This risk, generally known as “currency risk,” means that a strong U.S. dollar will reduce returns for U.S. investors while a weak U.S. dollar will increase those returns.

Foreign Economy Risk — The economies of certain foreign markets may not compare favorably with the economy of the United States with respect to such issues as growth of gross national product, reinvestment of capital, resources and balance of payments position. Certain foreign economies may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments, the imposition of economic sanctions against a particular country or countries, changes in international trading patterns, trade barriers and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental actions such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. In addition, the governments of certain countries may prohibit or impose substantial restrictions on foreign investments in their capital markets or in certain industries. Any of these actions could severely affect securities prices or impair the Fund’s ability to purchase or sell foreign securities or transfer the Fund’s assets or income back into the United States, or otherwise adversely affect the Fund’s operations.

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Other potential foreign market risks include foreign exchange controls, difficulties in pricing securities, defaults on foreign government securities, difficulties in enforcing legal judgments in foreign courts and political and social instability. Diplomatic and political developments, including rapid and adverse political changes, social instability, regional conflicts, terrorism and war, could affect the economies, industries and securities and currency markets, and the value of the Fund’s investments, in non-U.S. countries. These factors are extremely difficult, if not impossible, to predict and take into account with respect to the Fund’s investments.

Governmental Supervision and Regulation/Accounting Standards — Many foreign governments do not supervise and regulate stock exchanges, brokers and the sale of securities to the same extent as such regulations exist in the United States. They also may not have laws to protect investors that are comparable to U.S. securities laws. For example, some foreign countries may have no laws or rules against insider trading. Insider trading occurs when a person buys or sells a company’s securities based on material non-public information about that company. In addition, some countries may have legal systems that may make it difficult for the Fund to vote proxies, exercise shareholder rights, and pursue legal remedies with respect to its foreign investments. Accounting standards in other countries are not necessarily the same as in the United States. If the accounting standards in another country do not require as much detail as U.S. accounting standards, it may be harder for Fund management to completely and accurately determine a company’s financial condition.

Settlement Risk — Settlement and clearance procedures in certain foreign markets differ significantly from those in the United States. Foreign settlement and clearance procedures and trade regulations also may involve certain risks (such as delays in payment for or delivery of securities) not typically associated with the settlement of U.S. investments.

At times, settlements in certain foreign countries have not kept pace with the number of securities transactions. These problems may make it difficult for the Fund to carry out transactions. If the Fund cannot settle or is delayed in settling a purchase of securities, it may miss attractive investment opportunities and certain of its assets may be uninvested with no return earned thereon for some period. If the Fund cannot settle or is delayed in settling a sale of securities, it may lose money if the value of the security then declines or, if it has contracted to sell the security to another party, the Fund could be liable for any losses incurred.

European Economic Risk — The European financial markets have recently experienced volatility and adverse trends due to concerns about economic downturns in, or rising government debt levels of, several European countries. These events may spread to other countries in Europe. These events may affect the value and liquidity of certain of the Fund’s investments.

Responses to the financial problems by European governments, central banks and others, including austerity measures and reforms, may not work, may result in social unrest and may limit future growth and economic recovery or have other unintended consequences. Further defaults or restructurings by governments and others of their debt could have additional adverse effects on economies, financial markets and asset valuations around the world. In addition, the United Kingdom has voted to withdraw from the European Union, and one or more other countries may withdraw from the European Union and/or abandon the Euro, the common currency of the European Union. The impact of these actions, especially if they occur in a disorderly fashion, is not clear but could be significant and far reaching.

The securities of other investment companies and ETFs in which the Fund may invest may be leveraged. As a result, the Fund may be indirectly exposed to leverage through an investment in such securities. An investment in securities of other investment companies and ETFs that use leverage 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 (and, indirectly, the long-term returns of shares of the Fund) will be diminished.

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As with other investments, investments in other investment companies, including ETFs, are subject to market and selection risk. To the extent the Fund is held by an affiliated fund, the ability of the Fund itself to hold other investment companies may be limited.

The credit rating of a high yield security does not necessarily address its market value risk. Ratings and market value may change from time to time, positively or negatively, to reflect new developments regarding the issuer.

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Small movements in interest rates (both increases and decreases) may quickly and significantly reduce the value of certain mortgage-backed securities. The Fund’s investments in asset-backed securities are subject to risks similar to those associated with mortgage-related securities, as well as additional risks associated with the nature of the assets and the servicing of those assets. These securities also are subject to the risk of default on the underlying mortgages or assets, particularly during periods of economic downturn. Certain CMBS are issued in several classes with different levels of yield and credit protection. The Fund’s investments in CMBS with several classes may be in the lower classes that have greater risks than the higher classes, including greater interest rate, credit and prepayment risks.

Mortgage-backed securities may be either pass-through securities or collateralized mortgage obligations (“CMOs”). Pass-through securities represent a right to receive principal and interest payments collected on a pool of mortgages, which are passed through to security holders. CMOs are created by dividing the principal and interest payments collected on a pool of mortgages into several revenue streams (“tranches”) with different priority rights to portions of the underlying mortgage payments. Certain CMO tranches may represent a right to receive interest only (“IOs”), principal only (“POs”) or an amount that remains after floating-rate tranches are paid (an “inverse floater”). These securities are frequently referred to as “mortgage derivatives” and may be extremely sensitive to changes in interest rates. Interest rates on inverse floaters, for example, vary inversely with a short-term floating rate (which may be reset periodically). Interest rates on inverse floaters will decrease when short-term rates increase, and will increase when short-term rates decrease. These securities have the effect of providing a degree of investment leverage. In response to changes in market interest rates or other market conditions, the value of an inverse floater may increase or decrease at a multiple of the increase or decrease in the value of the underlying securities. If the Fund invests in CMO tranches (including CMO tranches issued by government agencies) and interest rates move in a manner not anticipated by Fund management, it is possible that the Fund could lose all or substantially all of its investment. TBA commitments are forward agreements for the purchase or sale of securities, including mortgage-backed securities for a fixed price, with payment and delivery on an agreed upon future settlement date. The specific securities to be delivered are not identified at the trade date. However, delivered securities must meet specified terms, including issuer, rate and mortgage terms. Certain mortgage-backed securities in which the Fund may invest may also provide a degree of investment leverage, which could cause the Fund to lose all or substantially all of its investment.

The mortgage market in the United States has experienced difficulties that may adversely affect the performance and market value of certain of the Fund’s mortgage-related investments. Delinquencies and losses on mortgage loans (including subprime and second-lien mortgage loans) generally have increased and may continue to increase, and a decline in or flattening of real-estate values (as has been experienced and may continue to be experienced in many housing markets) may exacerbate such delinquencies and losses. Also, a number of mortgage loan originators have experienced serious financial difficulties or bankruptcy. Reduced investor demand for mortgage loans and mortgage-related securities and increased investor yield requirements have caused limited liquidity in the secondary market for mortgage-related securities, which can adversely affect the market value of mortgage-related securities. It is possible that such limited liquidity in such secondary markets could continue or worsen.

Asset-backed securities entail certain risks not presented by mortgage-backed securities, including the risk that in certain states it may be difficult to perfect the liens securing the collateral backing certain asset-backed securities. In addition, certain asset-backed securities are based on loans that are unsecured, which means that there is no collateral to seize if the underlying borrower defaults.

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There is also a possibility that originators will not be able to sell participations in second lien loans, which would create greater credit risk exposure for the holders of such loans. Second lien loans share the same risks as other below investment grade securities.

An economic downturn generally leads to a higher non-payment rate, and a senior loan may lose significant value before a default occurs. Moreover, any specific collateral used to secure a senior loan may decline in value or become illiquid, which would adversely affect the senior loan’s value.

No active trading market may exist for certain senior loans, which may impair the ability of the Fund to realize full value in the event of the need to sell a senior loan and which may make it difficult to value senior loans. Adverse market conditions may impair the liquidity of some actively traded senior loans. To the extent that a secondary market does exist for certain senior loans, the market may be subject to irregular trading activity, wide bid/ask spreads and extended trade settlement periods. See “Liquidity Risk.”

Although senior loans in which the Fund will invest generally will be secured by specific collateral, there can be no assurance that liquidation of such collateral would satisfy the borrower’s obligation in the event of non-payment of scheduled interest or principal or that such collateral could be readily liquidated. In the event of the bankruptcy of a borrower, the Fund could experience delays or limitations with respect to its ability to realize the benefits of the collateral securing a senior loan. If the terms of a senior loan do not require the borrower to pledge additional collateral in the event of a decline in the value of the already pledged collateral, the Fund will be exposed to the risk that the value of the collateral will not at all times equal or exceed the amount of the borrower’s obligations under the senior loans. To the extent that a senior loan is collateralized by stock in the borrower or its subsidiaries, such stock may lose all of its value in the event of the bankruptcy of the borrower. Uncollateralized senior loans involve a greater risk of loss. Some senior loans are subject to the risk that a court, pursuant to fraudulent conveyance or other similar laws, could subordinate the senior loans to presently existing or future indebtedness of the borrower or take other action detrimental to lenders, including the Fund. Such court action could under certain circumstances include invalidation of senior loans.

If a senior loan is acquired through an assignment, the Fund may not be able to unilaterally enforce all rights and remedies under the loan and with regard to any associated collateral. If a senior loan is acquired through a participation, the Fund generally will have no right to enforce compliance by the borrower with the terms of the loan agreement against the borrower, and the Fund may not directly benefit from the collateral supporting the debt obligation in which it has purchased the participation. As a result, the Fund will be exposed to the credit risk of both the borrower and the institution selling the participation.

The senior loans in which the Fund invests are usually rated below investment grade. As a result, the risks associated with senior loans are similar to the risks of below investment grade securities, although senior loans are typically senior and secured in contrast to other below investment grade securities, which are often subordinated and unsecured. See “Junk Bonds Risk.” The higher standing of senior loans has historically resulted in generally higher recoveries in the event of a corporate reorganization. In addition, because their interest rates are typically adjusted for changes in short-term interest rates, senior loans generally are subject to less interest rate risk than other below investment grade securities, which are typically fixed rate.

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Senior loans made in connection with highly leveraged transactions are subject to greater risks than other senior loans. For example, the risks of default or bankruptcy of the borrower or the risks that other creditors of the borrower may seek to nullify or subordinate the Fund’s claims on any collateral securing the loan are greater in highly leveraged transactions.

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Other Risks of Investing in the Fund

The Fund may also be subject to certain other risks associated with its investments and investment strategies, including:

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Account Information

How to Choose the Share Class that Best Suits Your Needs

The Fund currently offers multiple share classes (Investor A, Investor C and Institutional Shares in this prospectus), each with its own sales charge and expense structure, allowing you to invest in the way that best suits your needs. Each share class represents an ownership interest in the same investment portfolio of the Fund. When you choose your class of shares, you should consider the size of your investment and how long you plan to hold your shares. Either your financial professional or your selected securities dealer, broker, investment adviser, service provider or industry professional (including BlackRock, The PNC Financial Services Group, Inc. (“PNC”) and their respective affiliates) (each a “Financial Intermediary”) can help you determine which share class is best suited to your personal financial goals. Investor A and Investor C Shares are sometimes referred to herein collectively as “Investor Shares.”

For example, if you select Institutional Shares of the Fund, you will not pay any sales charge. However, only certain investors may buy Institutional Shares. If you select Investor A Shares of the Fund, you generally pay a sales charge at the time of purchase and an ongoing service fee of 0.25% per year. You may be eligible for a sales charge reduction or waiver.

If you select Investor C Shares of the Fund, you will invest the full amount of your purchase price, but you will be subject to a distribution fee of 0.75% per year and a service fee of 0.25% per year under a plan adopted pursuant to Rule 12b-1 under the Investment Company Act. Because these fees are paid out of the Fund’s assets on an ongoing basis, over time these fees increase the cost of your investment and may cost you more than paying other types of sales charges. In addition, you may be subject to a deferred sales charge when you sell Investor C Shares of the Fund within one year. Classes with lower expenses will have higher net asset values and dividends relative to other share classes.

The Fund’s shares are distributed by BlackRock Investments, LLC (the “Distributor”), an affiliate of BlackRock.

The table below and on the following pages summarizes key features of each of the share classes of the Fund.

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The following pages will cover the additional details of each share class, including the Institutional Shares requirements, the sales charge table for Investor A Shares, reduced sales charge information, Investor C Share CDSC information, and sales charge waivers.

The availability of certain sales charge waivers and reductions will depend on whether you purchase your shares directly from the Fund or through a Financial Intermediary. Financial Intermediaries may have different policies and procedures regarding the availability of front-end sales charge waivers or deferred sales charge waivers, which are discussed below. In all instances, it is your responsibility to notify the Fund or your Financial Intermediary at the time of purchase of any relationship or other facts qualifying you for sales charge waivers or reductions. For waivers and discounts not available through a particular Financial Intermediary, shareholders will have to purchase Fund shares directly from the Fund or through another Financial Intermediary to receive these waivers or reductions. Please see the “Intermediary-Defined Sales Charge Waiver Policies” section to determine any sales charge waivers and reductions that may be available to you through your Financial Intermediary.

More information about existing sales charge reductions and waivers is available free of charge in a clear and prominent format via hyperlink at www.blackrock.com and in the SAI, which is available on the website or on request.

Details About the Share Classes

Investor A Shares — Initial Sales Charge Option

The following table shows the front-end sales charges that you may pay if you buy Investor A Shares. The offering price for Investor A Shares includes any front-end sales charge. The front-end sales charge expressed as a percentage of the offering price may be higher or lower than the charge described below due to rounding. Similarly, any contingent deferred sales charge paid upon certain redemptions of Investor A Shares expressed as a percentage of the applicable redemption amount may be higher or lower than the charge described below due to rounding. You may qualify for a reduced front-end sales charge. Purchases of Investor A Shares at certain fixed dollar levels, known as “breakpoints,” cause a reduction in the front-end sales charge. Once you achieve a breakpoint, you pay that sales charge on your

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entire purchase amount (and not just the portion above the breakpoint). If you select Investor A Shares, you will pay a sales charge at the time of purchase as shown in the following table.

No initial sales charge applies to Investor A Shares that you buy through reinvestment of Fund dividends or capital gains.

Sales Charges Reduced or Eliminated for Investor A Shares

There are several ways in which the sales charge can be reduced or eliminated. Purchases of Investor A Shares at certain fixed dollar levels, known as “breakpoints,” cause a reduction in the front-end sales charge (as described above in the “Investor A Shares — Initial Sales Charge Option” section). Additionally, the front-end sales charge can be reduced or eliminated through one or a combination of the following: a Letter of Intent, the right of accumulation, the reinstatement privilege (described under “Account Services and Privileges”), or a waiver of the sales charge (described below).

Reductions or eliminations through a Letter of Intent or the right of accumulation will apply to the value of all qualifying holdings in shares of mutual funds sponsored and advised by BlackRock or its affiliates (“BlackRock Funds”) owned by (a) the investor, or (b) the investor’s spouse and any children and a trust, custodial account or fiduciary account for the benefit of any such individuals. For this purpose, the value of an investor’s holdings means the offering price of the newly purchased shares (including any applicable sales charge) plus the current value (including any sales charges paid) of all other shares the investor already holds taken together.

See the “Intermediary-Defined Sales Charge Waiver Policies” section for sales charge reductions and waivers that may be available to customers of certain Financial Intermediaries.

Qualifying Holdings — Investor Shares, Institutional Shares (in most BlackRock Funds) and investments in the BlackRock CollegeAdvantage 529 Program.

Qualifying Holdings may include shares held in accounts held at a Financial Intermediary, including personal accounts, certain retirement accounts, UGMA/UTMA accounts, Joint Tenancy accounts, trust accounts and Transfer on Death accounts, as well as shares purchased by a trust of which the investor is a beneficiary. For purposes of the Letter of Intent and right of accumulation, the investor may not combine with the investor’s other holdings shares held in pension, profit sharing or other employer-sponsored retirement plans if those shares are held in the name of a nominee or custodian.

In order to receive a reduced sales charge, at the time an investor purchases shares of the Fund, the investor should inform the Financial Intermediary and/or BlackRock Funds of any other shares of the Fund or any other BlackRock Fund that qualify for a reduced sales charge. Failure by the investor to notify the Financial Intermediary or BlackRock Funds may result in the investor not receiving the sales charge reduction to which the investor is otherwise entitled.

The Financial Intermediary or BlackRock Funds may request documentation — including account statements and records of the original cost of the shares owned by the investor, the investor’s spouse and/or children showing that the investor qualifies for a reduced sales charge. The investor should retain these records because — depending on where an account is held or the type of account — the Fund and/or the Financial Intermediary or BlackRock Funds may not be able to maintain this information.

For more information, see the SAI or contact your Financial Intermediary.

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Letter of Intent

An investor may qualify for a reduced front-end sales charge immediately by signing a “Letter of Intent” stating the investor’s intention to buy a specified amount of Investor A, Investor C and/or Institutional Shares and/or make an investment through the BlackRock CollegeAdvantage 529 Program in one or more BlackRock Funds within the next 13 months that would, if bought all at once, qualify the investor for a reduced sales charge. The initial investment must meet the minimum initial purchase requirement. The 13-month Letter of Intent period commences on the day that the Letter of Intent is received by the Fund.

The market value of current holdings in the BlackRock Funds (including Investor A, Investor B, Investor C and Institutional Shares and the BlackRock CollegeAdvantage 529 Program Class A and Class C Units) as of the date of commencement that are eligible under the Right of Accumulation may be counted towards the sales charge reduction.

The investor must notify the Fund of (i) any current holdings in the BlackRock Funds and/or the BlackRock CollegeAdvantage 529 Program that should be counted towards the sales charge reduction and (ii) any subsequent purchases that should be counted towards the Letter of Intent.

During the term of the Letter of Intent, the Fund will hold Investor A Shares representing up to 5% of the indicated amount in an escrow account for payment of a higher sales load if the full amount indicated in the Letter of Intent is not purchased. If the full amount indicated is not purchased within the 13-month period, and the investor does not pay the higher sales load within 20 days, the Fund will redeem enough of the Investor A Shares held in escrow to pay the difference.

Right of Accumulation

Investors have a “right of accumulation” under which the current value of an investor’s existing Investor A and A1, Investor B, Investor C, C1, C2 and C3, and Institutional Shares in most BlackRock Funds and the investment in the BlackRock CollegeAdvantage 529 Program by the investor or by or on behalf of the investor’s spouse and children may be combined with the amount of the current purchase in determining whether an investor qualifies for a breakpoint and a reduced front-end sales charge. Financial Intermediaries may value current holdings of their customers differently for purposes of determining whether an investor qualifies for a breakpoint and a reduced front-end sales charge, although customers of the same Financial Intermediary will be treated similarly. In order to use this right, the investor must alert BlackRock to the existence of any previously purchased shares.

Other Front-End Sales Charge Waivers

The following persons may also buy Investor A Shares without paying a sales charge:

In addition, Financial Intermediaries may, in connection with a change in account type or otherwise in accordance with a Financial Intermediary’s policies and procedures, exchange one class of shares for Investor A Shares of the same Fund. In such cases, such exchange would not be subject to an Investor A Shares sales charge. The availability of Investor A Shares sales charge waivers may depend on the policies, procedures and trading platforms of your Financial Intermediary; consult your financial adviser.

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See the “Intermediary-Defined Sales Charge Waiver Policies” section for sales charge reductions and waivers that may be available to customers of certain Financial Intermediaries.