BlackRock Bond Index Fund

APRIL 30, 2014

Summary Prospectus

BlackRock Funds III | Investor A and Institutional Shares

►	BlackRock Bond Index Fund
	Investor A: BMOAX • Institutional: BMOIX

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) 441-7762 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 April 30, 2014, 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 BlackRock Bond Index Fund

Investment Objective

BlackRock Bond Index Fund (the “Fund”), a series of BlackRock Funds III (the “Trust”), seeks to provide investment results that correspond to the total return performance of fixed-income securities in the aggregate, as represented by the Barclays U.S. Aggregate Bond Index (the “Barclays U.S. Aggregate Index”).

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.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)¹		Investor A Shares		Institutional Shares
Management Fee¹		0.08%		0.08%
Distribution and/or Service (12b-1) Fees		0.25%		None
Other Expenses		0.09%		0.09%
Administration Fees^2,4	0.07%		0.07%
Independent Expenses³	0.02%		0.02%
Acquired Fund Fees and Expenses⁴		0.02%		0.02%
Total Annual Fund Operating Expenses⁴		0.44%		0.19%
Fee Waivers and/or Expense Reimbursements³		(0.02)%		(0.02)%
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements³		0.42%		0.17%

¹	The fees and expenses shown in the table above and the example that follows include the expenses of both the Fund and the Fund’s share of the allocated expenses of Bond Index Master Portfolio (the “Master Portfolio”), a series of Master Investment Portfolio (“MIP”). Management fees are paid by the Master Portfolio.
²	Administration Fees have been restated to reflect current fees.
³	Independent Expenses consist of the Fund’s allocable portion of the fees and expenses of the independent trustees of the Trust and MIP, counsel to such independent trustees and the independent registered public accounting firm that provides audit services to the Fund and the Master Portfolio. BlackRock Advisors, LLC (“BAL”), the administrator for the Fund, and BlackRock Fund Advisors (“BFA”), the investment adviser for the Master Portfolio, have contractually agreed to reimburse, or provide offsetting credits to, the Fund and the Master Portfolio, as applicable, for Independent Expenses through April 30, 2015. After giving effect to such contractual arrangements, Independent Expenses will be 0.00%. Such contractual arrangements may not be terminated prior to May 1, 2015 without the consent of the Boards of Trustees of the Trust and of MIP.
⁴	The 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 Acquired Fund Fees and Expenses or the restatement of Administration Fees to reflect current fees.

Example:

This Example is intended to help you compare the cost of investing in shares of the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in shares of 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
Investor A Shares	$43	$139	$244	$553
Institutional Shares	$17	$ 59	$105	$241

Portfolio Turnover:

The Master Portfolio 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 Master Portfolio’s portfolio turnover rate was 417% of the average value of its portfolio.

Principal Investment Strategies of the Fund

The Fund pursues its investment objective by seeking to match the total return performance of the Barclays U.S. Aggregate Index, which is composed of approximately 8,000 fixed-income securities. The fixed-income securities that comprise the Barclays U.S. Aggregate Index include U.S. Government securities and corporate bonds, as well as mortgage-backed securities, asset-backed securities and commercial mortgage-backed securities. All securities in the Barclays U.S. Aggregate Index are investment-grade. The Fund maintains a weighted average maturity consistent with that of the Barclays U.S. Aggregate Index, which generally ranges between 5 and 10 years. The Fund invests in a representative sample of these securities. Securities are selected for investment by the Fund in accordance with their relative proportion within the Barclays U.S. Aggregate Index as well as based on credit quality, issuer sector, maturity structure, coupon rates and callability, among other factors. BFA, the investment adviser to the Master Portfolio in which the Fund invests, considers investments that provide substantially similar exposure to securities in the Barclays U.S. Aggregate Index to be investments comprising the Fund’s benchmark index.

The Fund is managed by determining which securities are to be purchased or sold to reflect, to the extent feasible, the investment characteristics of its benchmark index. Under normal circumstances, at least 90% of the value of the Fund’s assets, plus the amount of any borrowing for investment purposes, is invested in securities comprising the Barclays U.S. Aggregate Index, which, for the Fund, are considered bonds.

The Fund is a “feeder” fund that invests all of its assets in the Master Portfolio of MIP, which has the same investment objective and strategies as the Fund. All investments are made at the Master Portfolio level. This structure is sometimes called a “master/feeder” structure. The Fund’s investment results will correspond directly to the investment results of the Master Portfolio. For simplicity, the prospectus uses the name of the Fund or the term “Fund” (as applicable) to include the Master Portfolio.

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 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 principal and interest payments 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 the issuer’s financial condition and on the terms of the securities.

	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.
■	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 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.
■	Index Fund Risk — An index fund has operating and other expenses while an index does not. As a result, while the Fund will attempt to track the Barclays U.S. Aggregate Index as closely as possible, it will tend to underperform the index to some degree over time. If an index fund is properly correlated to its stated index, the fund will perform poorly when the index performs poorly.
■	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 Obligations Risk — Certain securities in which the Fund may invest, including securities issued by certain U.S. Government agencies and U.S. Government sponsored enterprises, are not guaranteed by the U.S. Government or supported by the full faith and credit of the United States.

Performance Information

The information shows how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. Investor A and Institutional Shares of the Fund commenced operations on March 31, 2011. As a result, the returns in the bar chart and table for Investor A and Institutional Shares, prior to commencement of operations on March 31, 2011, are based on the Fund’s Class K Shares, which are offered in a separate prospectus, adjusted to reflect the fees and expenses applicable to Investor A and Institutional Shares. The average annual total return table (before and after taxes) compares the Fund’s average annual total return to that of the Barclays U.S. Aggregate Index. As with all such investments, past performance (before and after taxes) is not necessarily an indication of future results. If BFA, BAL and their 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 visiting http://www.blackrock.com/funds or can be obtained by phone at (800) 882-0052.

Investor A Shares

ANNUAL TOTAL RETURNS

BlackRock Bond Index Fund
As of 12/31

During the ten-year period shown in the bar chart, the highest return for a quarter was 4.49% (quarter ended December 31, 2008) and the lowest return for a quarter was –2.77% (quarter ended June 30, 2004). The year-to-date return as of March 31, 2014 was 1.76%.

As of 12/31/13 Average Annual Total Returns	1 Year	5 Years	10 Years
BlackRock Bond Index Fund — Investor A
Return Before Taxes	(2.63)%	3.89%	4.25%
Return After Taxes on Distributions	(4.63)%	2.47%	2.60%
Return After Taxes on Distributions and Sale of Shares	(1.35)%	2.51%	2.64%
BlackRock Bond Index Fund — Institutional
Return Before Taxes	(2.39)%	4.12%	4.45%
Barclays U.S. Aggregate Index (Reflects no deduction for fees, expenses or taxes)	(2.02)%	4.44%	4.55%

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. After-tax returns are shown for Investor A Shares only, and the after-tax returns for Institutional Shares will vary.

Investment Adviser

The Master Portfolio’s investment adviser is BlackRock Fund Advisors (previously defined as “BFA”).

Portfolio Managers

Name	Portfolio Manager of the Master Portfolio Since	Title
James Mauro	2011	Director of BlackRock, Inc.
Scott Radell, CFA	2009	Managing Director of BlackRock, Inc.

Purchase and Sale of Fund Shares

You may purchase or redeem shares of the Fund each day the New York Stock Exchange is open. To purchase or sell shares, you should contact your financial professional or your selected securities dealer, broker, investment adviser, service provider or industry professional (including BFA, The PNC Financial Services Group, Inc. and their respective affiliates) (each a “Financial Intermediary”), or, if you hold your shares through the Fund, you should contact the Fund

by phone at (800) 441-7762, by mail (c/o BlackRock Funds III, P.O. Box 9819, Providence, Rhode Island 02940-8019), or by the Internet at www.blackrock.com/funds. The Fund’s initial and subsequent investment minimums generally are as follows, although the Fund may reduce or waive the minimums in some cases:

	Investor A Shares	Institutional Shares
Minimum Initial Investment	$1,000 for all accounts except: • $250 for certain fee-based programs. • $100 for certain employer-sponsored retirement plans. • $50, if establishing an Automatic Investment Plan.	$2 million for institutions and individuals. Institutional Shares are available to clients of registered investment advisers who have $250,000 invested in the Fund.
Minimum Additional Investment	$50 for all accounts (with the exception of certain employer-sponsored retirement plans which may have a lower minimum).	No subsequent minimum.

Tax Information

The Fund’s dividends and distributions may be subject to 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 retirement plan, in which case you may be subject to Federal income tax upon withdrawal 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 # 811-07332

BlackRock Bond Index Fund — Investor

SPRO-BI-0414