Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Portfolio Turnover. The Fund may pay transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in the Annual Fund Operating Expenses or in the Example, affect the Fund’s performance. There has been no portfolio turnover because the Fund has not commenced operations as of the date of this prospectus (the “Prospectus”).

Principal Investment Strategies

The Fund seeks to achieve its investment objective by investing, under normal circumstances, at least 80% of its assets in U.S. dollar-denominated CLOs that are, at the time of purchase, rated AAA (or equivalent) by at least one of the major rating agencies or, if unrated, determined by the Fund management team to be of similar quality. The Fund’s 80% investment policy is non-fundamental and may be changed without shareholder approval upon 60 days’ prior written notice to shareholders. The Fund may invest in CLOs of any maturity. The Fund may purchase CLOs in both the primary market (i.e., directly from arranging banks) and in the secondary market.

A CLO is ordinarily issued by a trust or other special purpose entity (“SPE”) and is typically collateralized by a pool of loans, which may include, among others, domestic and non-U.S. senior secured loans, senior unsecured loans, “covenant lite” loans (which have few or no financial maintenance covenants) and subordinate corporate loans, including loans that may be rated below investment grade or equivalent unrated loans, and to a lesser extent, high yield bonds rated below investment grade (commonly called “junk bonds”), held by such issuer. The cash flows from the SPE are split into two or more portions, called tranches, varying in risk and yield. The riskiest portion of a CLO is the “equity” tranche, which bears the first loss from defaults from the bonds or loans in the SPE and serves to protect the other, more senior tranches from default (though such protection is not complete). Since it is partially protected from defaults, a “senior” tranche of a CLO typically has higher ratings and lower yields than its underlying securities, and may be rated AAA.

The Fund may invest up to 20% of its assets in U.S. dollar-denominated CLOs that are, at the time of purchase, rated AA or A (or equivalent) by at least one of the major rating agencies or, if unrated, determined by the Fund management team to be of similar quality.

The Fund will not invest more than 10% of its net assets in any single CLO.

The Fund may invest in floating- and fixed-rate CLOs, but will not invest more than 10% of its net assets in fixed-rate CLOs.

The Fund may also buy when-issued securities and participate in delayed delivery transactions.

The Fund is classified as non-diversified under the Investment Company Act of 1940, as amended (the “Investment Company Act”).

Summary of Principal Risks

As with any investment, you could lose all or part of your investment in the Fund, and the Fund’s performance could trail that of other investments. The Fund is subject to certain risks, including the principal risks noted below, any of which may adversely affect the Fund’s net asset value per share (“NAV”), trading price, yield, total return and ability to meet its investment objective. Unlike many exchange-traded funds (“ETFs”), the Fund is not an index-based ETF. The relative significance of each risk factor below may change over time and you should review each risk factor carefully.

Collateralized Loan Obligations Risk. The risks of investing in CLOs depend largely on the type of the collateral securities and the tranche of the CLO. In stressed market conditions, it is possible that even senior CLO debt tranches, such as those in which the Fund will invest, could experience losses due to actual defaults, downgrades of the underlying collateral by rating agencies, forced liquidation of the collateral pool due to a failure of coverage tests, increased sensitivity to defaults due to collateral default and the disappearance of protecting tranches, market anticipation of defaults as well as investor aversion to CLO securities as an asset class. While the Fund invests principally in CLO

tranches that are rated AAA, such ratings do not constitute a guarantee of credit quality and may be downgraded. To the extent that the Fund invests in CLO tranches rated below AAA, the risks of investing in CLOs will be greater. Split rated CLOs, which are CLOs that receive different ratings from two or more rating agencies, will be considered to have the higher credit rating. To the extent that the Fund invests in unrated CLO tranches, the Fund’s ability to achieve its investment objective will be more dependent on Fund management’s credit analysis than would be the case when the Fund invests in rated CLO tranches.

Further, interest on certain tranches of a CLO may be paid in kind or deferred and capitalized (paid in the form of obligations of the same type rather than cash), which involves continued exposure to default risk with respect to such payments. Fund management may not be able to accurately predict how specific CLOs or the portfolio of underlying loans or bonds for such CLOs will perform based on financial models or react to changes or stresses in the market, including changes in interest rates.

CLOs, and their underlying loan obligations, are typically not registered for sale to the public and therefore are subject to certain restrictions on transfer and sale, potentially making them less liquid than other types of securities. Some unrated CLO securities may not have an active trading market or may be difficult to value. Additionally, when the Fund purchases a newly issued CLO security in the primary market (rather than from the secondary market), there often may be a delayed settlement period. As a

result, the proceeds from the sale of CLO securities may not be readily available to make additional investments or to meet the Fund’s redemption obligations. During a delayed settlement period, the liquidity of the CLO may be further reduced. During periods of limited liquidity and higher price volatility, the Fund’s ability to acquire or dispose of CLO securities at a price and time the Fund deems advantageous may be impaired. To the extent the extended settlement process gives rise to short-term liquidity needs, the Fund may hold additional cash, sell investments or temporarily borrow from banks and other lenders. CLO securities are generally considered to be long-term investments and there is no guarantee that an active secondary market will exist or be maintained for any given CLO security.

CLO Manager Risk. The CLOs in which the Fund invests are managed by investment advisers independent of BFA. CLO managers are responsible for selecting, managing and replacing the underlying bank loans or bonds within a CLO. CLO managers may have limited operating histories and may be subject to conflicts of interests, including managing the assets of other clients or other investment vehicles, or receiving fees that incentivize maximizing the yield, and indirectly the risk, of a CLO. Adverse developments with respect to a CLO manager, such as personnel and resource constraints, regulatory issues or other developments that may impact the ability and/or performance of the CLO manager, may adversely impact the performance of the CLO securities in which the Fund invests.

Interest Rate Risk. During periods of very low or negative interest rates, the

Fund may be unable to maintain positive returns or pay dividends to Fund shareholders. 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, result in heightened market volatility and detract from the Fund’s performance to the extent the Fund is exposed to such interest rates. Additionally, under certain market conditions in which interest rates are low and the market prices for portfolio securities have increased, the Fund may have a very low or even negative yield. A low or negative yield would cause the Fund to lose money in certain conditions and over certain time periods. An increase in interest rates will generally cause the value of securities held by the Fund to decline, may lead to heightened volatility in the fixed-income markets and may adversely affect the liquidity of certain fixed-income investments, including those held by the Fund. 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. The historically low interest rate environment in recent years heightens the risks associated with rising interest rates.

Call Risk. During periods of falling interest rates, an issuer of a callable security held by the Fund may “call” or repay the security before its stated maturity, and the Fund may have to reinvest the proceeds in securities with lower yields, which would result in a

decline in the Fund’s income, or in securities with greater risks or with other less favorable features. CLOs are typically structured such that, after a specified period of time, the majority investor in the equity tranche can call (i.e., redeem) the securities issued by the CLO in full. The Fund may not be able to accurately predict when or which of its CLO investments may be called, resulting in the Fund having to reinvest the proceeds in unfavorable circumstances, which in turn could cause in a decline in the Fund’s income.

Extension Risk. During periods of rising interest rates, certain debt obligations may be paid off substantially more slowly than originally anticipated and the value of those securities may fall sharply, resulting in a decline in the Fund’s income and potentially in the value of the Fund’s investments.

Prepayment Risk. During periods of falling interest rates, issuers of certain debt obligations may repay principal prior to the security’s maturity, which may cause the Fund to have to reinvest in securities with lower yields or higher risk of default, resulting in a decline in the Fund’s income or return potential.

Credit Risk. Debt issuers and other counterparties may be unable or unwilling to make timely interest and/or principal payments when due or otherwise honor their obligations. Changes in an issuer’s credit rating or the market’s perception of an issuer’s creditworthiness may also adversely affect the value of the Fund’s investment in that issuer. The degree of credit risk depends on an issuer’s or counterparty’s financial condition and on the terms of an obligation. For CLOs, the primary source of credit risk is the

ability of the underlying portfolio of loans or bonds to generate sufficient cash flow to pay investors on a full and timely basis when principal and/or interest payments are due. Default in payment on the underlying loans or bonds will result in less cash flow from the underlying portfolio and, in turn, less funds available to pay investors in the CLO.

Income Risk. The Fund’s income may decline if interest rates fall. This decline in income can occur because the Fund may subsequently invest in lower-yielding CLOs as CLOs in its portfolio mature, are near maturity or are called, or the Fund otherwise needs to purchase additional CLOs.

LIBOR Risk. The Fund may be exposed to financial instruments that are tied to London Interbank Offered Rate (“LIBOR”) to determine payment obligations, financing terms, hedging strategies or investment value. The Fund’s investments may pay interest at floating rates based on LIBOR or may be subject to interest caps or floors based on LIBOR. The Fund may also obtain financing at floating rates based on LIBOR. Derivative instruments utilized by the Fund may also reference LIBOR.

LIBOR Replacement Risk. As part of the phase-out of the use of LIBOR, the rate’s administrator, ICE Benchmark Administration Limited (“IBA”), discontinued two USD LIBOR settings immediately after publication on December 31, 2021. The United Kingdom’s Financial Conduct Authority (“FCA”), which regulates LIBOR, and IBA previously announced that a majority of USD LIBOR settings will no longer be published after June 30, 2023. While the FCA is requiring the

IBA to publish certain LIBOR settings, potentially to include USD settings, on a “synthetic” basis, the “synthetic” methodology is not based on panel bank contributions and is not intended to be representative of the interest rates in the underlying market. The Fund may have investments linked to other interbank offered rates, such as the Euro Overnight Index Average (“EONIA”), which may also cease to be published. Various financial industry groups continue planning for the transition away from LIBOR, but there are challenges to converting certain securities and transactions to a new reference rate, such as the Secured Overnight Financing Rate (“SOFR”), which is intended to replace USD LIBOR. For example, at times, SOFR has proven to be more volatile than the 3-month USD LIBOR. Working groups and regulators in other countries have suggested other alternatives for their markets, including the Sterling Overnight Interbank Average Rate (“SONIA”) in England.

Neither the effect of the LIBOR transition process nor its ultimate success can yet be known. The transition process might lead to increased volatility and illiquidity in markets for, and reduce the effectiveness of new hedges placed against, instruments whose terms currently include LIBOR. While some existing LIBOR-based instruments may contemplate a scenario where LIBOR is no longer available by providing for an alternative rate-setting methodology, there may be significant uncertainty regarding the effectiveness of any such alternative methodologies to replicate LIBOR. Not all existing LIBOR-based instruments may have alternative rate-setting provisions and there remains

uncertainty regarding the willingness and ability of issuers to add alternative rate-setting provisions in certain existing instruments. Global regulators have advised market participants to cease entering into new contracts using LIBOR as a reference rate, and it is possible that investments in LIBOR-based instruments could invite regulatory scrutiny. In addition, a liquid market for newly issued instruments that use a reference rate other than LIBOR still may be developing. There may also be challenges for the Fund to enter into hedging transactions against such newly issued instruments until a market for such hedging transactions develops. All of the aforementioned may adversely affect the Fund’s performance or NAV.

Asset Class Risk. Securities and other assets in the Fund’s portfolio may underperform in comparison to the general financial markets, a particular financial market or other asset classes.

Assets Under Management (AUM) Risk. From time to time, an Authorized Participant (as defined in the Creations and Redemptions section of this Prospectus a third-party investor, the Fund’s adviser or an affiliate of the Fund’s adviser, or a fund may invest in the Fund and hold its investment for a specific period of time in order to facilitate commencement of the Fund’s operations or to allow the Fund to achieve size or scale. There can be no assurance that any such entity would not redeem its investment or that the size of the Fund would be maintained at such levels, which could negatively impact the Fund.

Authorized Participant Concentration Risk. Only an Authorized Participant (as defined in the Creations and

Redemptions section of this Prospectus) may engage in creation or redemption transactions directly with the Fund, and none of those Authorized Participants is obligated to engage in creation and/or redemption transactions. The Fund has a limited number of institutions that may act as Authorized Participants on an agency basis (i.e., on behalf of other market participants). To the extent that Authorized Participants exit the business or are unable to proceed with creation or redemption orders with respect to the Fund and no other Authorized Participant is able to step forward to create or redeem, Fund shares may be more likely to trade at a premium or discount to NAV and possibly face trading halts or delisting.

Concentration Risk. The Fund may be susceptible to loss due to adverse events that affect the Fund’s investments more than the market as a whole, to the extent that the Fund’s investments are concentrated in the securities and/or other assets of a particular issuer or issuers, country, group of countries, region, market, industry, group of industries, sector, market segment or asset class.

Cybersecurity Risk. Failures or breaches of the electronic systems of the Fund, the Fund’s adviser, distributor and other service providers, market makers, Authorized Participants or the issuers of securities in which the Fund invests have the ability to cause disruptions, negatively impact the Fund’s business operations and/or potentially result in financial losses to the Fund and its shareholders. While the Fund has established business continuity plans and risk management systems seeking to address system

breaches or failures, there are inherent limitations in such plans and systems. Furthermore, the Fund cannot control the cybersecurity plans and systems of the Fund’s service providers, market makers, Authorized Participants or issuers of securities in which the Fund invests.

Floating Rate Securities Risk. Securities with floating or variable interest rates can be less sensitive to interest rate changes than securities with fixed interest rates, but may decline in value if their coupon rates do not reset as high, or as quickly, as comparable market interest rates, and generally carry lower yields than fixed securities of the same maturity. Although floating rate securities are less sensitive to interest rate risk than fixed-rate securities, they are subject to credit risk and default risk, which could impair their value.

High Portfolio Turnover Risk. High portfolio turnover (considered by the Fund to mean higher than 100% annually) may result in increased transaction costs to the Fund, including brokerage commissions, dealer mark-ups and other transaction costs on the sale of the securities and on reinvestment in other securities.

Illiquid Investments Risk. The Fund may not acquire any illiquid investment if, immediately after the acquisition, the Fund would have invested more than 15% of its net assets in illiquid investments. An illiquid investment is any investment that the Fund reasonably expects cannot be sold or disposed of in current market conditions in seven calendar days or less without significantly changing the market value of the investment. To the

extent the Fund holds illiquid investments, the illiquid investments may reduce the returns of the Fund because the Fund may be unable to transact at advantageous times or prices. In addition, if the Fund is limited in its ability to sell illiquid investments during periods when shareholders are redeeming their shares, the Fund will need to sell liquid securities to meet redemption requests and illiquid securities will become a larger portion of the Fund’s holdings. During periods of market volatility, liquidity in the market for the Fund’s shares may be impacted by the liquidity in the market for the underlying securities or instruments held by the Fund, which could lead to the Fund’s shares trading at a premium or discount to the Fund’s NAV.

Infectious Illness Risk. A widespread outbreak of an infectious illness, such as the COVID-19 pandemic, may result in travel restrictions, disruption of healthcare services, prolonged quarantines, cancellations, supply chain disruptions, business closures, lower consumer demand, layoffs, ratings downgrades, defaults and other significant economic, social and political impacts. Markets may experience temporary closures, extreme volatility, severe losses, reduced liquidity and increased trading costs. Such events may adversely affect the Fund and its investments and may impact the Fund’s ability to purchase or sell securities or cause increased premiums or discounts to the Fund’s NAV. Despite the development of vaccines, the duration of the COVID-19 pandemic and its effects cannot be predicted with certainty.

Issuer Risk. The performance of the Fund depends on the performance of individual securities to which the Fund has exposure. The Fund may be adversely affected if an issuer of underlying securities held by the Fund is unable or unwilling to repay principal or interest when due. Changes to the financial condition or credit rating of an issuer of those securities may cause the value of the securities to decline.

Large Shareholder and Large-Scale Redemption Risk. Certain shareholders, including an Authorized Participant, a third-party investor, the Fund’s adviser or an affiliate of the Fund’s adviser, a market maker, or another entity, may from time to time own or manage a substantial amount of Fund shares, or may invest in the Fund and hold their investment for a limited period of time. There can be no assurance that any large shareholder or large group of shareholders would not redeem their investment. Redemptions of a large number of Fund shares may adversely affect the Fund’s liquidity and net assets. Because the Fund generally redeems Creation Units solely for cash, these redemptions could require the Fund to dispose of assets to meet the redemption requests, which can accelerate the realization of taxable income and/or capital gains and cause the Fund to make taxable distributions to its shareholders earlier than the Fund otherwise would have. In addition, under certain circumstances, non-redeeming shareholders may be treated as receiving a disproportionately large taxable distribution during or with respect to such year. In some circumstances, the Fund may hold a relatively large proportion of its assets in cash in

anticipation of large redemptions, diluting its investment returns. These large redemptions may also force the Fund to sell portfolio securities when it might not otherwise do so, which may negatively impact the Fund’s NAV, increase the Fund’s brokerage costs and/or have a material effect on the market price of the Fund shares.

Management Risk. The Fund is subject to management risk, which is the risk that the investment process, techniques and analyses applied by BFA will not produce the desired results, and those securities or other financial instruments selected by BFA may result in returns that are inconsistent with the Fund’s investment objective. In addition, legislative, regulatory, or tax developments may affect the investment techniques available to BFA in connection with managing the Fund and may also adversely affect the ability of the Fund to achieve its investment objective.

Market Risk. The Fund could lose money over short periods due to short-term market movements and over longer periods during more prolonged market downturns. Local, regional or global events such as war, acts of terrorism, the spread of infectious illness or other public health issues, recessions, or other events could have a significant impact on the Fund and its investments and could result in increased premiums or discounts to the Fund’s NAV.

Market Trading Risk. The Fund faces numerous market trading risks, including the potential lack of an active market for Fund shares, losses from trading in secondary markets, periods of high volatility and disruptions in the creation/redemption process. Unlike

some ETFs that track specific indexes, the Fund does not seek to replicate the performance of a specified index. Index-based ETFs have generally traded at prices that closely correspond to NAV per share. Given the high level of transparency of the Fund’s holdings, BFA believes that the trading experience of the Fund should be similar to that of index-based ETFs. However, ETFs that do not seek to replicate the performance of a specified index have a limited trading history and, therefore, there can be no assurance as to whether, and/or the extent to which, the Fund’s shares will trade at a premium or discount to NAV. ANY OF THESE FACTORS, AMONG OTHERS, MAY LEAD TO THE FUND’S SHARES TRADING AT A PREMIUM OR DISCOUNT TO NAV.

Non-Diversification Risk. The Fund is classified as “non-diversified.” This means that, compared with other funds that are classified as "diversified," the Fund may invest a greater percentage of its assets in securities issued by or representing a small number of issuers. As a result, the Fund’s performance may depend on the performance of a small number of issuers.

Operational Risk. The Fund is exposed to operational risks arising from a number of factors, including, but not limited to, human error, processing and communication errors, errors of the Fund’s service providers, counterparties or other third parties, failed or inadequate processes and technology or systems failures. The Fund and BFA seek to reduce these operational risks through controls and procedures. However, these measures do not address every possible risk and

may be inadequate to address significant operational risks.

Risk of Investing in the U.S. Certain changes in the U.S. economy, such as when the U.S. economy weakens or when its financial markets decline, may have an adverse effect on the securities to which the Fund has exposure.

Small Fund Risk. When the Fund’s size is small, the Fund may experience low trading volume and wide bid/ask spreads. In addition, the Fund may face the risk of being delisted if the Fund does not meet certain conditions of the listing exchange. Any resulting liquidation of the Fund could cause the Fund to incur elevated transaction costs for the Fund and negative tax consequences for its shareholders.

Structured Products Risk. Holders of structured products bear risks of the underlying investments, index or reference obligation and are subject to counterparty risk. The Fund may have the right to receive payments only from the structured product, and generally does not have direct rights against the issuer or the entity that sold the assets to be securitized. Certain structured products may be thinly traded or have a limited trading market. In addition to the general risks associated with debt securities discussed herein, structured products carry additional risks, including, but not limited to: the possibility that distributions from collateral securities will not be adequate to make interest or other payments; the quality of the collateral may decline in value or default; and the possibility that the structured products are subordinate to other classes. Structured notes are based upon the movement of one or more factors, including currency exchange rates,

interest rates, reference bonds and stock indices, and changes in interest rates and impact of these factors may cause significant price fluctuations. Additionally, changes in the reference instrument or security may cause the interest rate on the structured note to be reduced to zero.

When-Issued and Delayed Delivery Securities and Forward Commitments Risk. When-issued and delayed delivery securities and forward commitments involve the risk that the security the Fund buys will lose value prior to its delivery. There also is the risk that the security will not be issued or that the other party to the transaction will not meet its obligation. If this occurs, the Fund may lose both the investment opportunity for the assets it set aside to pay for the security and any gain in the security’s price.

Performance Information

Because the Fund has not commenced operations as of the date of this Prospectus, it does not have performance information an investor would find useful in evaluating the risks of investing in the Fund. The Fund’s benchmark is the JP Morgan CLOIE AAA Index.

Management

Investment Adviser. BlackRock Fund Advisors.

Portfolio Managers. Owen Butler, Peter Hirsh and Nidhi Patel (the “Portfolio Managers”) are jointly and primarily responsible for the day-to-day management of the Fund. Messrs. Butler and Hirsh and Ms. Patel have been Portfolio Managers of the Fund since 2022.

Purchase and Sale of Fund Shares

The Fund is an ETF. Individual shares of the Fund may only be bought and sold in the secondary market through a broker-dealer. Because ETF shares trade at market prices rather than at NAV, shares may trade at a price greater than NAV (a premium) or less than NAV (a discount). An investor may incur costs attributable to the difference between the highest price a buyer is willing to pay to purchase shares of the Fund (bid) and the lowest price a seller is willing to accept for shares of the Fund (ask) when buying or selling shares in the secondary market (the “bid-ask spread”).

Tax Information

The Fund intends to make distributions that may be taxable to your as ordinary income or capital gains, unless you are investing through a tax-deferred arrangement such as a 401(k) plan or an individual retirement account (“IRA”), in which case, your distributions generally will be taxable when withdrawn.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase shares of the Fund through a broker-dealer or other financial intermediary (such as a bank), BFA or other related companies may pay the intermediary for marketing activities and presentations, educational training programs, conferences, the development of technology platforms and reporting systems or other services related to the

sale or promotion of the Fund. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your salesperson to recommend the Fund over another investment. Ask your salesperson or visit your financial intermediary’s website for more information.