July 27, 2018

Summary Prospectus

BlackRock Allocation Target Shares  |  BATS: Series M Portfolio

►	Series M Portfolio
	BRAMX

Before you invest, you may want to review the Fund’s prospectus, which contains more information about the Fund and its risks. You can find the Fund’s prospectus (including amendments and supplements) and other information about the Fund, including the Fund’s statement of additional information and shareholder report, online at http://www.blackrock.com/prospectus. You can also get this information at no cost by calling (800) 882-0052 or by sending an e-mail request to prospectus.request@blackrock.com, or from your financial professional. The Fund’s prospectus and statement of additional information, both dated July 27, 2018, as amended and supplemented from time to time, are incorporated by reference into (legally made a part of) this Summary Prospectus.

This Summary Prospectus contains information you should know before investing, including information about risks. Please read it before you invest and keep it for future reference.

The Securities and Exchange Commission has not approved or disapproved these securities or passed upon the adequacy of this Summary Prospectus. Any representation to the contrary is a criminal offense.

Not FDIC Insured • May Lose Value • No Bank Guarantee

Summary Prospectus

Key Facts About BATS: Series M Portfolio

Investment Objective

The investment objective of the BATS: Series M Portfolio (the “Fund”) is to seek to maximize total return, consistent with income generation and prudent investment management.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.

Shareholder Fees (Fees paid directly from your investment)	BATS: Series M Portfolio Shares
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	None
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	None
Annual Fund Operating Expenses (Expenses that you pay each year as a percentage of the value of your investment)	BATS: Series M Portfolio Shares
Management Fee	None
Distribution and/or Service (12b-1) Fees	None
Other Expenses	0.08%
Acquired Fund Fees and Expenses1	0.01%
Total Annual Fund Operating Expenses1	0.09%
Fee Waivers and/or Expense Reimbursements2	(0.08)%
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements2	0.01% 3

1	Total Annual Fund Operating Expenses do not correlate to the ratio of expenses to average net assets given in the Fund’s most recent annual report, which does not include the Acquired Fund Fees and Expenses.
2	As described in the “Management of the Funds” section of the Fund’s prospectus beginning on page 55, pursuant to the management agreement between BlackRock Advisors, LLC (“BlackRock”) and BlackRock Allocation Target Shares, on behalf of the Fund, BlackRock has contractually agreed to waive all fees and pay or reimburse all fees and expenses of the Fund, except extraordinary expenses, indefinitely. Extraordinary expenses may include Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses.
3	You should also be aware that the Fund is an investment option for certain “wrap-fee” programs or other separately managed account clients for which BlackRock Investment Management, LLC or certain of its affiliates (individually or collectively referred to as “BIM LLC”) receives compensation pursuant to an investment management agreement. Wrap-fee program participants pay a “wrap-fee” to the sponsor of the program which typically covers investment advice and transaction costs on trades executed with the sponsor or a designated broker-dealer. You should read carefully the wrap-fee or other program brochure provided to you by your program sponsor or investment adviser. The brochure is required to include information about the fees charged to you and, in case of a wrap-fee program, the fees paid by the sponsor to BIM LLC.

Example:

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

	1 Year	3 Years	5 Years	10 Years
BATS: Series M Portfolio Shares	$1	$3	$6	$13

Portfolio Turnover:

The Fund pays 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 shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 1,515% of the average value of its portfolio.

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Principal Investment Strategies of the Fund

In pursuit of the investment objective, the Fund will principally invest in the following securities:

■ commercial and residential mortgage-backed securities;

■ asset-backed securities;

■ collateralized mortgage obligations;

■ U.S. Treasury and agency securities;

■ cash equivalent investments;

■ when-issued and delayed delivery securities;

■ derivatives; and

■ dollar rolls.

Under normal circumstances, the Fund invests at least 80% of its total assets in fixed-income instruments. This 80% policy is a non-fundamental policy of the Fund and may not be changed without 60 days’ prior notice to shareholders.

The management team evaluates sectors of the bond market and individual securities within these sectors.The management team may, when consistent with the Fund’s investment objective, buy or sell options or futures on a security or an index of securities, or enter into interest rate or foreign currency transactions, including swaps (collectively, commonly known as derivatives).

The Fund may only buy securities that are rated investment grade at the time of purchase by at least one major rating agency or, if unrated, determined by the management team to be of similar quality.

The Fund may engage in active and frequent trading of portfolio instruments to achieve its investment objective.

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 principal risks of investing in the Fund.

■	Debt Securities Risk — Debt securities, such as bonds, involve interest rate risk, credit risk, extension risk, and prepayment risk, among other things.
	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

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	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.
	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.
■	Derivatives Risk — The Fund’s use of derivatives may increase its costs, reduce the Fund’s returns and/or increase volatility. Derivatives involve significant risks, including:
	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.
■	Dollar Rolls Risk — Dollar rolls involve the risk that the market value of the securities that the Fund is committed to buy may decline below the price of the securities the Fund has sold. These transactions may involve leverage.
■	High Portfolio Turnover Risk — The Fund may engage in active and frequent trading of its portfolio securities. High portfolio turnover (more than 100%) 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. The sale of Fund portfolio securities may result in the realization and/or distribution to shareholders of higher capital gains or losses as compared to a fund with less active trading policies. These effects of higher than normal portfolio turnover may adversely affect Fund performance. In addition, investment in

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	mortgage dollar rolls and participation in to-be-announced (“TBA”) transactions may significantly increase the Fund’s portfolio turnover rate. A TBA transaction is a method of trading mortgage-backed securities where the buyer and seller agree upon general trade parameters such as agency, settlement date, par amount, and price at the time the contract is entered into but the mortgage-backed securities are delivered in the future, generally 30 days later.
■	Leverage Risk — Some transactions may give rise to a form of economic leverage. These transactions may include, among others, derivatives, and may expose the Fund to greater risk and increase its costs. The use of leverage may cause the Fund to liquidate portfolio positions when it may not be advantageous to do so to satisfy its obligations or to meet any required asset segregation requirements. Increases and decreases in the value of the Fund’s portfolio will be magnified when the Fund uses leverage.
■	Liquidity Risk — Liquidity risk exists when particular investments are difficult to purchase or sell. The Fund’s investments in illiquid securities may reduce the returns of the Fund because it may be difficult to sell the illiquid securities at an advantageous time or price. To the extent that the Fund’s principal investment strategies involve derivatives or securities with substantial market and/or credit risk, the Fund will tend to have the greatest exposure to liquidity risk. Liquidity risk may be the result of, among other things, the reduced number and capacity of traditional market participants to make a market in fixed-income securities or the lack of an active market. Liquid investments may become illiquid or less liquid after purchase by the Fund, particularly during periods of market turmoil. Illiquid and relatively less liquid investments may be harder to value, especially in changing markets, and if the Fund is forced to sell these investments to meet redemption requests or for other cash needs, the Fund may suffer a loss. This may be magnified in a rising interest rate environment or other circumstances where investor redemptions from fixed-income mutual funds may be higher than normal. In addition, when there is illiquidity in the market for certain securities, the Fund, due to limitations on illiquid investments, may be subject to purchase and sale restrictions.
■	Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money.
■	Mortgage- and Asset-Backed Securities Risks — Mortgage- and asset-backed securities represent interests in “pools” of mortgages or other assets, including consumer loans or receivables held in trust. Mortgage- and asset-backed securities are subject to credit, interest rate, prepayment and extension risks. These securities also are subject to risk of default on the underlying mortgage or asset, particularly during periods of economic downturn. Small movements in interest rates (both increases and decreases) may quickly and significantly reduce the value of certain mortgage-backed securities.
■	U.S. Government Issuer Risk — Treasury obligations may differ in their interest rates, maturities, times of issuance and other characteristics. Obligations of U.S. Government agencies and authorities are supported by varying degrees of credit but generally are not backed by the full faith and credit of the U.S. Government. No assurance can be given that the U.S. Government will provide financial support to its agencies and authorities if it is not obligated by law to do so.
■	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

The information shows you how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the Bloomberg Barclays MBS Index. To the extent that dividends and distributions have been paid by the Fund, the performance information for the Fund in the chart and table assumes reinvestment of the dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. The table includes all applicable fees. If the Fund’s investment manager and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s performance, including its current net asset value, can be obtained by phone at 800-882-0052.

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ANNUAL TOTAL RETURNS
BATS: Series M Portfolio
As of 12/31

During the ten-year period shown in the bar chart, the highest return for a quarter was 7.40% (quarter ended September 30, 2011) and the lowest return for a quarter was -3.22% (quarter ended December 31, 2010). The year-to-date return as of June 30, 2018 was -0.79%.

As of 12/31/17 Average Annual Total Returns	1 Year	5 Years	10 Years
BATS: Series M Portfolio
Return Before Taxes	2.61%	2.29%	4.22%
Return After Taxes on Distributions	1.20%	1.02%	2.64%
Return After Taxes on Distributions and Sale of Fund Shares	1.47%	1.17%	2.70%
Bloomberg Barclays MBS Index (Reflects no deduction for fees, expenses or taxes)	2.47%	2.04%	3.84%

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Investment Manager

The Fund’s investment manager is BlackRock Advisors, LLC (previously defined as “BlackRock”).

Portfolio Managers

Name	Portfolio Manager of the Fund Since	Title
Akiva Dickstein	2012	Managing Director of BlackRock, Inc.
Matthew Kraeger	2012	Managing Director of BlackRock, Inc.
Michael Heilbronn	2015	Director of BlackRock, Inc.

Purchase and Sale of Fund Shares

Shares of the Fund may be purchased and held only by or on behalf of separately managed account clients who have retained BIM LLC to manage their accounts, or who have requested that their investment adviser consider investment recommendations provided by BIM LLC in connection with the management of their accounts.

Purchase and redemption orders generally are made based on instructions from BIM LLC (or other investment adviser to whom BIM LLC provides investment recommendations). Purchase and redemption orders are processed at the net asset value next calculated after the broker-dealer receives the order on behalf of the account each day the New York Stock Exchange is open.

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	BATS: Series M Portfolio
Minimum Initial Investment	There is no minimum amount for initial investments.
Minimum Additional Investment	There is no minimum amount for additional investments.

Tax Information

The Fund’s dividends and distributions may be subject to U.S. federal income taxes and may be taxed as ordinary income or capital gains, unless you are a tax-exempt investor or are investing through a qualified tax-exempt plan described in section 401(a) of the Internal Revenue Code, in which case you may be subject to U.S. federal income tax when distributions are received from such tax-deferred arrangements.

Payments to Broker/Dealers and Other Financial Intermediaries

If you purchase shares of the Fund through a financial intermediary, the Fund and BlackRock Investments, LLC, the Fund’s distributor, or its affiliates may pay the financial intermediary for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing the financial intermediary and your individual financial professional to recommend the Fund over another investment. Ask your individual financial professional or visit your financial intermediary’s website for more information.

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INVESTMENT COMPANY ACT FILE # 811-21457

SPRO-BATSM-0718