Blackrock Funds III

09/25/2024 | Press release | Distributed by Public on 09/25/2024 10:33

Summary Prospectus by Investment Company - Form 497K

LP Index 2070 Fund - SP (INV)
SEPTEMBER 18, 2024

Summary Prospectus

BlackRock Funds III | Investor A and Institutional Shares

BlackRock LifePath® Index 2070 Fund

Investor A: LIYAX • Institutional: LIYIX

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), reports to shareholders, and other information about the Fund, including the Fund's statement of additional information, online at https://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 [email protected], or from your financial professional. The Fund's prospectus and statement of additional information, both dated September 18, 2024, 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 LifePath® Index 2070 Fund

Investment Objective

The investment objective of BlackRock LifePath® Index 2070 Fund ("LifePath Index 2070 Fund" or the "Fund"), a series of BlackRock Funds III (the "Trust"), is to seek to provide for retirement outcomes based on quantitatively measured risk. In pursuit of this objective, LifePath Index 2070 Fund will be broadly diversified across global asset classes, with asset allocations becoming more conservative over time.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy, hold and sell shares of LifePath Index 2070 Fund. You may pay other fees, such as brokerage commissions and other fees to your financial professional or your selected securities dealer, broker, investment adviser, service provider or industry professional (including BlackRock Fund Advisors ("BFA") and its affiliates) (each, a "Financial Intermediary"), which are not reflected in the table and example below.

Annual Fund Operating Expenses
(expenses that you pay each year as a percentage of the value of your investment)
Investor A
Shares
Institutional
Shares

Management Fee1

0.05% 0.05%

Distribution and/or Service (12b-1) Fees

0.25% None

Other Expenses1,2,3

0.28% 0.28%

Administration Fees1

0.09%   0.09%  

Independent Expenses2,3

0.19%   0.19%  

Acquired Fund Fees and Expenses1

0.05% 0.05%

Total Annual Fund Operating Expenses

0.63% 0.38%

Fee Waivers and/or Expense Reimbursements1,3

(0.24)% (0.24)%

Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements1,3

0.39% 0.14%
1

As described in the "Management of the Fund" section of the Fund's prospectus beginning on page 57, BFA and BlackRock Advisors, LLC ("BAL") have contractually agreed to reimburse the Fund for Acquired Fund Fees and Expenses up to a maximum amount equal to the combined Management Fee and Administration Fee of each share class through June 30, 2026. In addition, BFA has contractually agreed to waive its management fees by the amount of investment advisory fees the Fund pays to BFA indirectly through its investment in money market funds managed by BFA or its affiliates, through June 30, 2026. The contractual agreements may be terminated upon 90 days' notice by a majority of the non-interested trustees of the Trust or by a vote of a majority of the outstanding voting securities of the Fund.

2

Other Expenses are based on estimated amounts for the Fund's current fiscal year.

3

Independent Expenses consist of the Fund's allocable portion of the fees and expenses of the independent trustees of the Trust, counsel to such independent trustees and the independent registered public accounting firm that provides audit services to the Fund. BAL and BFA have contractually agreed to reimburse, or provide offsetting credits to, the Fund for Independent Expenses through June 30, 2035. After giving effect to such contractual arrangements, Independent Expenses will be 0.00%. Such contractual arrangements may not be terminated prior to July 1, 2035 without the consent of the Board of Trustees of the Trust.

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

Investor A Shares

$ 40 $ 136

Institutional Shares

$ 14 $ 56

2

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. There has been no portfolio turnover because the Fund has not commenced operations as of the date of this prospectus.

Principal Investment Strategies of the Fund

LifePath Index 2070 Fund allocates and reallocates its assets among a combination of equity and bond index funds and money market funds (the "Underlying Funds") in proportions based on its own comprehensive investment strategy.

LifePath Index 2070 Fund seeks to provide for retirement outcomes based on quantitatively measured risk. BFA employs a multi-dimensional approach to assess risk for LifePath Index 2070 Fund and to determine LifePath Index 2070 Fund's allocation across asset classes. As part of this multi-dimensional approach, BFA aims to quantify risk using proprietary risk measurement tools that, among other things, analyze historical and forward-looking securities market data, including risk, asset class correlations, and expected returns. Under normal circumstances, the Fund intends to invest primarily in affiliated open-end index funds and affiliated exchange-traded funds ("ETFs").

LifePath Index 2070 Fund will invest, under normal circumstances, at least 80% of its assets in securities or other financial instruments that are components of or have economic characteristics similar to the securities included in its custom benchmark index, the LifePath Index 2070 Fund Custom Benchmark. LifePath Index 2070 Fund is designed for investors expecting to retire or to begin withdrawing assets around the year 2070. The Fund employs a "passive" management approach, attempting to invest in a portfolio of assets whose performance is expected to match approximately the performance of the Fund's custom benchmark index. As of the date of this prospectus, the Fund expects to hold approximately 99% of its assets in Underlying Funds designed to track particular equity indexes, approximately 1% of its assets in Underlying Funds designed to track particular bond indexes and the remainder of its assets in Underlying Funds that invest primarily in money market instruments. Certain Underlying Funds may invest in real estate investment trusts ("REITs"), foreign securities, emerging market securities, below investment-grade bonds and derivative securities or instruments, such as options and futures, the value of which is derived from another security, a currency or an index, when seeking to match the performance of a particular market index. The Fund and certain Underlying Funds may also lend securities with a value up to 331/3% of their respective total assets to financial institutions that provide cash or securities issued or guaranteed by the U.S. Government as collateral.

Under normal circumstances, the asset allocation will change over time according to a predetermined "glide path" as the Fund approaches its target date. The glide path below represents the shifting of asset classes over time. As the glide path shows, the Fund's asset allocations become more conservative - prior to retirement - as time elapses. This reflects the need for reduced investment risks as retirement approaches and the need for lower volatility of the Fund, which may be a primary source of income after retirement.

LifePath Index 2070 Fund is one of a group of funds referred to as the "LifePath Index Funds," each of which seeks to provide for retirement outcomes based on quantitatively measured risk that investors on average may be willing to accept given a particular time horizon. The following chart illustrates the glide path - the target allocation among asset classes as the LifePath Index Funds approach their target dates:

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The following table lists the target allocation by years until retirement:

Years Until Retirement Equity Funds
(Includes REITs)
Fixed-Income
Funds

45

99 % 1 %

40

99 % 1 %

35

99 % 1 %

30

99 % 1 %

25

95 % 5 %

20

87 % 13 %

15

77 % 23 %

10

65 % 35 %

5

53 % 47 %

0

40 % 60 %

The asset allocation targets are established by the portfolio managers. The investment team, including the portfolio managers, meets regularly to assess market conditions, review the asset allocation targets of the Fund, and determine whether any changes are required to enable the Fund to achieve its investment objective.

Although the asset allocation targets listed for the glide path are general, long-term targets, BFA may periodically adjust the proportion of equity index funds and fixed-income index funds in the Fund, based on an assessment of the current market conditions, the potential contribution of each asset class to the expected risk and return characteristics of the Fund, reallocations of Fund composition to reflect intra-year movement along the glide path and other factors. In general, such adjustments will be limited; however, BFA may determine that a greater degree of variation is warranted to protect the Fund or achieve its investment objective.

BFA's second step in the structuring of the Fund is the selection of the Underlying Funds. Factors such as fund classifications, historical risk and performance, and the relationship to other Underlying Funds in the Fund are considered when selecting Underlying Funds. The specific Underlying Funds selected for the Fund are determined at BFA's discretion and may change as deemed appropriate to allow the Fund to meet its investment objective. See the "Details About the Fund - Information About the Underlying Funds" section of the prospectus for a list of the Underlying Funds, their classification into equity, fixed income or money market funds and a brief description of their investment objectives and primary investment strategies.

Within the prescribed percentage allocations to equity and fixed-income index funds, BFA seeks to diversify the Fund. The allocation to Underlying Funds that track equity indexes may be further diversified by style (including both value and growth), market capitalization (including large cap, mid cap, small cap and emerging growth), region (including domestic and international (including emerging markets)) or other factors. The allocation to Underlying Funds that track fixed-income indexes may be further diversified by sector (including government, corporate, agency, and other sectors), duration (a calculation of the average life of a bond which measures its price risk), credit quality (including non-investment grade debt or junk bonds), geographic location (including U.S. and foreign-issued securities), or other

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factors. Though BFA seeks to diversify the Fund, certain Underlying Funds may concentrate their investments in specific sectors or geographic regions or countries. The percentage allocation to the various styles of equity and fixed-income Underlying Funds is determined at the discretion of the investment team and can be changed to reflect the current market environment.

Principal Risks of Investing in the Fund

Risk is inherent in all investing. The value of your investment in LifePath Index 2070 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. An investment in the Fund is not a bank deposit and it is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The following is a summary description of principal risks of investing in the Fund and/or the Underlying Funds. References to the Fund in the description of risks below may include the Underlying Funds in which the Fund invests, as applicable. The relative significance of each risk factor below may change over time and you should review each risk factor carefully.

Principal Risks of the Fund's Investment Strategies

Equity Securities Risk - Stock markets are volatile. The price of equity securities fluctuates based on changes in a company's financial condition and overall market and economic conditions.

Investments in Underlying Funds Risk - Because the Fund invests substantially all of its assets in Underlying Funds, its investment performance is related to the performance of the Underlying Funds. The Fund's net asset value will change with changes in the value of the Underlying Funds and other securities in which it invests. An investment in the Fund will entail more direct and indirect costs and expenses than a direct investment in the Underlying Funds.

Allocation Risk - The Fund's ability to achieve its investment objective depends upon the Fund's asset class allocation and the mix of Underlying Funds. There is a risk that the asset class allocation or the combination of Underlying Funds may be incorrect in view of actual market conditions. In addition, the asset allocation or the combination of Underlying Funds determined by BFA could result in underperformance as compared to funds with similar investment objectives and strategies.

Retirement Income Risk - The Fund does not provide a guarantee that sufficient capital appreciation will be achieved to provide adequate income at and through retirement. The Fund also does not ensure that you will have assets in your account sufficient to cover your retirement expenses or that you will have enough saved to be able to retire in the target year identified in the Fund's name; this will depend on the amount of money you have invested in the Fund, the length of time you have held your investment, the returns of the markets over time, the amount you spend in retirement, and your other assets and income sources.

Affiliated Fund Risk - In managing the Fund, BFA will have authority to select and substitute underlying funds and ETFs. BFA may be subject to potential conflicts of interest in selecting underlying funds and ETFs because the fees paid to BFA by some underlying funds and ETFs are higher than the fees paid by other underlying funds and ETFs. However, BFA is a fiduciary to the Fund and is legally obligated to act in the Fund's best interests when selecting underlying funds and ETFs. If an underlying fund or ETF holds interests in an affiliated fund, the Fund may be prohibited from purchasing shares of that underlying fund or ETF.

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. The value of a security or other asset may decline due to changes in general market conditions, economic trends or events that are not specifically related to the issuer of the security or other asset, or factors that affect a particular issuer or issuers, exchange, country, group of countries, region, market, industry, group of industries, sector or asset class. Local, regional or global events such as war, acts of terrorism, the spread of infectious illness or other public health issues like pandemics or epidemics, recessions, or other events could have a significant impact on the Fund and its investments. 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.

An outbreak of an infectious coronavirus (COVID-19) that was first detected in December 2019 developed into a global pandemic that has resulted in numerous disruptions in the market and has had significant economic impact leaving general concern and uncertainty. Although vaccines have been developed and approved for use by various governments, the duration of the pandemic and its effects cannot be predicted with certainty. The impact of this coronavirus, and other epidemics and pandemics that may arise in the future, could affect the economies of many nations, individual companies and the market in general ways that cannot necessarily be foreseen at the present time.

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Risk of Investing in the United States - 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.

Principal Risks of the Underlying Funds

Asset ClassRisk- Securities and other assets or financial instruments in the underlying index of an Underlying Fund or in an Underlying Fund's portfolio may underperform in comparison to the general financial markets, a particular financial market or other asset classes.

Authorized Participant Concentration Risk - Only an authorized participant may engage in creation or redemption transactions directly with an ETF, and none of those authorized participants is obligated to engage in creation and/or redemption transactions. The Underlying Funds that are ETFs have 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 an ETF and no other authorized participant is able to step forward to create or redeem, the ETF shares may be more likely to trade at a premium or discount to net asset value and possibly face trading halts or delisting. Authorized participant concentration risk may be heightened for ETFs that invest in securities issued by non-U.S. issuers or other securities or instruments that have lower trading volumes.

Concentration Risk - To the extent that an underlying index of an Underlying Fund is concentrated in the securities of companies, a particular market, industry, group of industries, sector or asset class, country, region or group of countries, that Underlying Fund may be adversely affected by the performance of those securities, may be subject to increased price volatility and may be more susceptible to adverse economic, market, political or regulatory occurrences affecting that market, industry, group of industries, sector or asset class, country, region or group of countries.

Currency Risk - Because the net asset value of an Underlying Fund that is an ETF is determined in U.S. dollars, the Underlying Fund's net asset value could decline if the currency of a non-U.S. market in which the Underlying Fund invests depreciates against the U.S. dollar or if there are delays or limits on repatriation of such currency. Currency exchange rates can be very volatile and can change quickly and unpredictably. As a result, the net asset value of an Underlying Fund that is an ETF may change quickly and without warning.

Custody Risk - Less developed securities markets are more likely to experience problems with the clearing and settling of trades, as well as the holding of securities by local banks, agents and depositories.

Depositary Receipts Risk - Depositary receipts are generally subject to the same risks as the foreign securities that they evidence or into which they may be converted. In addition to investment risks associated with the underlying issuer, depositary receipts expose the Fund to additional risks associated with the non-uniform terms that apply to depositary receipt programs, credit exposure to the depository bank and to the sponsors and other parties with whom the depository bank establishes the programs, currency risk and the risk of an illiquid market for depositary receipts. The issuers of unsponsored depositary receipts are not obligated to disclose information that is, in the United States, considered material. Therefore, there may be less information available regarding these issuers and there may not be a correlation between such information and the market value of the depositary receipts. While depositary receipts provide an alternative to directly purchasing underlying foreign securities in their respective markets and currencies, they continue to be subject to many of the risks associated with investing directly in foreign securities, including political, economic, and currency risk.

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:

Leverage Risk - The Fund's use of derivatives can magnify the Fund's gains and losses. Relatively small market movements may result in large changes in the value of a derivatives position and can result in losses that greatly exceed the amount originally invested.

Market Risk - Some derivatives are more sensitive to interest rate changes and market price fluctuations than other securities. The Fund could also suffer losses related to its derivatives positions as a result of unanticipated market movements, which losses are potentially unlimited. Finally, BFA 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.

Counterparty Risk - Derivatives are also subject to counterparty risk, which is the risk that the other party in the transaction will be unable or unwilling to fulfill its contractual obligation, and the related risks of having concentrated exposure to such a counterparty.

Illiquidity 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.

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Operational Risk - The use of derivatives includes the risk of potential operational issues, including documentation issues, settlement issues, systems failures, inadequate controls and human error.

Legal Risk - The risk of insufficient documentation, insufficient capacity or authority of counterparty, or legality or enforceability of a contract.

Volatility and Correlation 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.

Valuation Risk - Valuation for derivatives may not be readily available in the market. 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.

Emerging Markets Risk - Emerging markets are riskier than more developed markets because they tend to develop unevenly and may never fully develop. Investments in emerging markets may be considered speculative. Emerging markets are more likely to experience hyperinflation and currency devaluations, which adversely affect returns to U.S. investors. In addition, many emerging securities markets have far lower trading volumes and less liquidity than developed markets.

Foreign Securities Risk - Foreign investments often involve special risks not present in U.S. investments that can increase the chances that the Fund will lose money. These risks include:

The Fund generally holds its foreign securities and cash in foreign banks and securities depositories, which may be recently organized or new to the foreign custody business and may be subject to only limited or no regulatory oversight.

Changes in foreign currency exchange rates can affect the value of the Fund's portfolio.

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.

The governments of certain countries, or the U.S. Government with respect to certain countries, may prohibit or impose substantial restrictions through capital controls and/or sanctions on foreign investments in the capital markets or certain industries in those countries, which may prohibit or restrict the ability to own or transfer currency, securities, derivatives or other assets.

Many foreign governments do not supervise and regulate stock exchanges, brokers and the sale of securities to the same extent as does the United States and may not have laws to protect investors that are comparable to U.S. securities laws.

Settlement and clearance procedures in certain foreign markets may result in delays in payment for or delivery of securities not typically associated with settlement and clearance of U.S. investments.

The Fund's claims to recover foreign withholding taxes may not be successful, and if the likelihood of recovery of foreign withholding taxes materially decreases, due to, for example, a change in tax regulation or approach in the foreign country, accruals in the Fund's net asset value for such refunds may be written down partially or in full, which will adversely affect the Fund's net asset value.

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 as well as acts of war in the region. These events may spread to other countries in Europe and may affect the value and liquidity of certain of the Fund's investments.

Geographic Risk- Some of the companies in which the Fund invests are located in parts of the world that have historically been prone to natural disasters, such as earthquakes, tornadoes, volcanic eruptions, droughts, floods, hurricanes or tsunamis, and are economically sensitive to environmental events. Any such event may adversely impact the economies of these geographic areas or business operations of companies in these geographic areas, causing an adverse impact on the value of the Fund.

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Income Risk - Income risk is the risk that the Fund's yield will vary as short-term securities in its portfolio mature and the proceeds are reinvested in securities with different interest rates.

Inflation-Indexed Bonds Risk - The principal value of an investment is not protected or otherwise guaranteed by virtue of the Fund's investments in inflation-indexed bonds.

Inflation-indexed bonds are fixed-income securities whose principal value is periodically adjusted according to the rate of inflation. If the index measuring inflation falls, the principal value of inflation-indexed bonds will be adjusted downward, and consequently the interest payable on these securities (calculated with respect to a smaller principal amount) will be reduced.

Repayment of the original bond principal upon maturity (as adjusted for inflation) is guaranteed in the case of U.S. Treasury inflation-indexed bonds. For bonds that do not provide a similar guarantee, the adjusted principal value of the bond repaid at maturity may be less than the original principal value.

The value of inflation-indexed bonds is expected to change in response to changes in real interest rates. Real interest rates are tied to the relationship between nominal interest rates and the rate of inflation. If nominal interest rates increase at a faster rate than inflation, real interest rates may rise, leading to a decrease in value of inflation-indexed bonds. Short-term increases in inflation may lead to a decline in value. Any increase in the principal amount of an inflation-indexed bond will be considered taxable ordinary income, even though investors do not receive their principal until maturity.

Periodic adjustments for inflation to the principal amount of an inflation-indexed bond may give rise to original issue discount, which will be includable in the Fund's gross income. Due to original issue discount, the Fund may be required to make annual distributions to shareholders that exceed the cash received, which may cause the Fund to liquidate certain investments when it is not advantageous to do so. Also, if the principal value of an inflation-indexed bond is adjusted downward due to deflation, amounts previously distributed in the taxable year may be characterized in some circumstances as a return of capital.

Indexing Investment Risk - The Fund is not actively managed, and BFA generally does not attempt to take defensive positions under any market conditions, including declining markets.

Index-Related Risk - There is no guarantee that an Underlying Fund's investment results will have a high degree of correlation to those of its underlying index or that the Underlying Fund will achieve its investment objective. Market disruptions or high volatility, other unusual market circumstances and regulatory restrictions could have an adverse effect on an Underlying Fund's ability to adjust its exposure to the required levels in order to track its underlying index. Errors in index data, index computations or the construction of an underlying index in accordance with its methodology may occur from time to time and may not be identified and corrected by the index provider for a period of time or at all, which may have an adverse impact on an Underlying Fund and its shareholders. Unusual market conditions or other unforeseen circumstances (such as natural disasters, political unrest or war) may impact the index provider or a third-party data provider and could cause the index provider to postpone a scheduled rebalance. This could cause an underlying index to vary from its normal or expected composition.

An index fund has operating and other expenses while an index does not. As a result, while an Underlying Fund will attempt to track its underlying index as closely as possible, it will tend to underperform the underlying 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.

Issuer Risk - Fund performance depends on the performance of individual securities to which the Fund has exposure. Changes in the financial condition or credit rating of an issuer of those securities may cause the value of the securities to decline.

Large-Capitalization Companies Risk - Large-capitalization companies may be less able than smaller capitalization companies to adapt to changing market conditions. Large-capitalization companies may be more mature and subject to more limited growth potential compared with smaller capitalization companies. During different market cycles, the performance of large- capitalization companies has trailed the overall performance of the broader securities markets.

Large Shareholder and Large-Scale Redemption Risk - Certain shareholders, including a third-party investor, the Fund's adviser or an affiliate of the Fund's adviser, 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 its 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 by large shareholders or a large group of shareholders could have a significant negative impact on the Fund. Redemptions of a large number of Fund shares could require the Fund to dispose of assets to meet the redemption requests, which can accelerate the realization of taxable income 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

8

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 and increase the Fund's brokerage costs and/or accelerate the realization of taxable income and/or capital gains to shareholders. In addition, large redemptions can result in the Fund's current expenses being allocated over a smaller asset base, which generally results in an increase in the Fund's expense ratio. Because large redemptions can adversely affect a portfolio manager's ability to implement a fund's investment strategy, the Fund also reserves the right to redeem in-kind, subject to certain conditions.

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 the applicable requirements of the Investment Company Act, and the rules thereunder. Increases and decreases in the value of the Fund's portfolio will be magnified when the Fund uses leverage.

Management Risk - As an Underlying Fund may not fully replicate its underlying index, it is subject to the risk that the Underlying Fund's investment manager's investment strategy may not produce the intended results.

Money Market Securities Risk - If market conditions improve while the Fund has invested some or all of its assets in high quality money market securities, this strategy could result in reducing the potential gain from the market upswing, thus reducing the Fund's opportunity to achieve its investment objective.

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.

National Closed Market Trading Risk - To the extent that the underlying securities or other instruments held by an Underlying Fund that is an ETF trade on foreign exchanges or in foreign markets that may be closed when the securities exchange on which the Underlying Fund's shares trade is open, there are likely to be deviations between the current price of such an underlying security and the last quoted price for the underlying security (i.e., an Underlying Fund's quote from the closed foreign market). The impact of a closed foreign market on an Underlying Fund is likely to be greater where a large portion of the Underlying Fund's underlying securities or other instruments trade on that closed foreign market or when the foreign market is closed for unscheduled reasons. These deviations could result in premiums or discounts to one or more of the Underlying Funds' net asset values that may be greater than those experienced by other ETFs.

Passive Investment Risk - Because BFA does not select individual companies in the underlying indexes for certain Underlying Funds, those Underlying Funds may hold securities of companies that present risks that an investment adviser researching individual securities might seek to avoid.

Preferred Securities Risk - Preferred securities may pay fixed or adjustable rates of return. Preferred securities are subject to issuer-specific and market risks applicable generally to equity securities. In addition, a company's preferred securities generally pay dividends only after the company makes required payments to holders of its bonds and other debt. For this reason, the value of preferred securities will usually react more strongly than bonds and other debt to actual or perceived changes in the company's financial condition or prospects. Preferred securities of smaller companies may be more vulnerable to adverse developments than preferred securities of larger companies.

Privatization Risk - Some countries in which the Fund invests have privatized, or have begun the process of privatizing, certain entities and industries. Privatized entities may lose money or be re-nationalized.

Real Estate-Related Securities Risk - The main risk of real estate-related securities is that the value of the underlying real estate may go down. Many factors may affect real estate values. These factors include both the general and local economies, vacancy rates, changes in rent schedules, tenant bankruptcies, the ability to re-lease space under expiring leases on attractive terms, the amount of new construction in a particular area, the laws and regulations (including zoning, environmental and tax laws) affecting real estate and the costs of owning, maintaining and improving real estate. The availability of mortgage financing and changes in interest rates may also affect real estate values. If the Fund's real estate-related investments are concentrated in one geographic area or in one property type, the Fund will be particularly subject to the risks associated with that area or property type. Many issuers of real estate-related securities are highly leveraged, which increases the risk to holders of such securities. The value of the securities the Fund buys will not necessarily track the value of the underlying investments of the issuers of such securities. In addition, certain issuers of real estate-related securities may have developed or commenced development on properties and may develop additional properties in the future. Real estate development involves significant risks in addition to those involved in the ownership and operation of established properties. Real estate securities may have limited diversification and are, therefore, subject to risks inherent in operating and financing a limited number of projects. Real estate securities are also subject to heavy cash flow dependency and defaults by borrowers or tenants.

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REIT Investment Risk - Investments in REITs involve unique risks. REITs may have limited financial resources, may trade less frequently and in limited volume, may engage in dilutive offerings of securities and may be more volatile than other securities. REIT issuers may also fail to maintain their exemptions from investment company registration or fail to qualify for the "dividends paid deduction" under the Internal Revenue Code, which allows REITs to reduce their corporate taxable income for dividends paid to their shareholders.

Representative Sampling Risk - Representative sampling is a method of indexing that involves investing in a representative sample of securities that collectively have a similar investment profile to the index and resemble the index in terms of risk factors and other key characteristics. A passively managed ETF may or may not hold every security in the index. When an ETF deviates from a full replication indexing strategy to utilize a representative sampling strategy, the ETF is subject to an increased risk of tracking error, in that the securities selected in the aggregate for the ETF may not have an investment profile similar to those of its index.

Repurchase Agreements Risk - If the other party to a repurchase agreement defaults on its obligation under the agreement, the Fund may suffer delays and incur costs or lose money in exercising its rights under the agreement. If the seller fails to repurchase the security and the market value of the security declines, the Fund may lose money.

Shares of an ETF May Trade at Prices Other Than Net Asset Value - Shares of an ETF trade on exchanges at prices at, above or below their most recent net asset value. The per share net asset value of an ETF is calculated at the end of each business day and fluctuates with changes in the market value of the ETF's holdings since the most recent calculation. The trading prices of an ETF's shares fluctuate continuously throughout trading hours based on market supply and demand rather than net asset value. The trading prices of an ETF's shares may deviate significantly from net asset value during periods of market volatility. Any of these factors may lead to an ETF's shares trading at a premium or discount to net asset value. However, because shares can be created and redeemed in creation units, which are aggregated blocks of shares that authorized participants who have entered into agreements with the ETF's distributor can purchase or redeem directly from the ETF, at net asset value (unlike shares of many closed-end funds, which frequently trade at appreciable discounts from, and sometimes at premiums to, their net asset values), large discounts or premiums to the net asset value of an ETF are not likely to be sustained over the long-term. While the creation/redemption feature is designed to make it likely that an ETF's shares normally trade on exchanges at prices close to the ETF's next calculated net asset value, exchange prices are not expected to correlate exactly with an ETF's net asset value due to timing reasons as well as market supply and demand factors. In addition, disruptions to creations and redemptions or the existence of extreme market volatility may result in trading prices that differ significantly from net asset value. If a shareholder purchases at a time when the market price is at a premium to the net asset value or sells at a time when the market price is at a discount to the net asset value, the shareholder may sustain losses. The use of cash creations and redemptions may also cause the ETFs' shares to trade in the market at greater bid-ask spreads or greater premiums or discounts to the ETFs' NAV.

Small and Mid-Capitalization Company Risk - Companies with small or mid-size market capitalizations will normally have more limited product lines, markets and financial resources and will be dependent upon a more limited management group than larger capitalized companies. In addition, it is more difficult to get information on smaller companies, which tend to be less well known, have shorter operating histories, do not have significant ownership by large investors and are followed by relatively few securities analysts.

Structured Securities Risk - Because structured securities of the type in which the Fund may invest typically involve no credit enhancement, their credit risk generally will be equivalent to that of the underlying instruments, index or reference obligation and will also be subject to counterparty risk. The Fund may have the right to receive payments only from the structured security, and generally does not have direct rights against the issuer or the entity that sold the assets to be securitized. In addition to the general risks associated with debt securities discussed herein, structured securities 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 securities are subordinate to other classes. The Fund is permitted to invest in a class of structured securities that is either subordinated or unsubordinated to the right of payment of another class. Subordinated structured securities typically have higher yields and present greater risks than unsubordinated structured securities. Structured securities are typically sold in private placement transactions, and there currently is no active trading market for structured securities. Structured securities 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 security to be reduced to zero. Certain issuers of such structured securities may be deemed to be "investment companies" as defined in the Investment Company Act. As a result, the Fund's investment in such securities may be limited by certain investment restrictions contained in the Investment Company Act.

Tax Risk - Although the Fund intends to invest primarily in securities the interest on which, in the opinion of counsel to the issuer, is exempt from federal income tax, the IRS has generally not ruled on the taxability of the securities. An assertion by the IRS that a portfolio security is not exempt from Federal income tax (contrary to

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indications from the issuer) could affect the Fund's and shareholder's income tax liability for the current or past years and could create liability for information reporting penalties. In addition, an IRS assertion of taxability may impair the liquidity and the fair market value of the securities.

Tracking Error Risk - Tracking error is the divergence of an Underlying Fund's performance from that of its underlying index. Tracking error may occur because of differences between the securities and other instruments held in an Underlying Fund's portfolio and those included in its underlying index, pricing differences (including, as applicable, differences between a security's price at the local market close and an Underlying Fund's valuation of a security at the time of calculation of an Underlying Fund's NAV), differences in transaction costs, an Underlying Fund's holding of uninvested cash, differences in timing of the accrual of or the valuation of dividends or other distributions, interest, the requirements to maintain pass-through tax treatment, portfolio transactions carried out to minimize the distribution of capital gains to shareholders, changes to an underlying index and the cost to an Underlying Fund of complying with various new or existing regulatory requirements. These risks may be heightened during times of increased market volatility or other unusual market conditions. In addition, tracking error may result because an Underlying Fund incurs fees and expenses, while its underlying index does not.

Treasury Obligations Risk - Direct obligations of the U.S. Treasury have historically involved little risk of loss of principal if held to maturity. However, due to fluctuations in interest rates, the market value of such securities may vary during the period shareholders own shares of the Fund. In addition, notwithstanding that U.S. Treasury obligations are backed by the full faith and credit of the United States, circumstances could arise that could prevent the timely payment of interest or principal, such as reaching the legislative "debt ceiling." Such non-payment could result in losses to the Fund and substantial negative consequences for the U.S. economy and the global financial system.

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.

Valuation Risk - The price an Underlying Fund could receive upon the sale of a security or other asset may differ from the Underlying Fund's valuation of the security or other asset and from the value used by its underlying index, particularly for securities or other assets that trade in low volume or volatile markets or that are valued using a fair value methodology as a result of trade suspensions or for other reasons. In addition, the value of the securities or other assets in an Underlying Fund's portfolio may change on days or during time periods when shareholders will not be able to purchase or sell the Underlying Fund's shares. Authorized Participants who purchase or redeem Underlying Fund shares on days when an Underlying Fund is holding fair-valued securities may receive fewer or more shares, or lower or higher redemption proceeds, than they would have received had the securities not been fair valued or been valued using a different methodology. The ability to value investments may be impacted by technological issues or errors by pricing services or other third-party service providers.

Variable and Floating Rate Instrument Risk - Variable and floating rate securities provide for periodic adjustment in the interest rate paid on the securities. These securities may be subject to greater illiquidity risk than other fixed income securities, meaning the absence of an active market for these securities could make it difficult for the Fund to dispose of them at any given time.

Performance Information

Because the LifePath Index 2070 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 will compare its performance to that of the Russell 1000® Index, the Bloomberg U.S. Aggregate Bond Index and the LifePath Index 2070 Fund Custom Benchmark, a customized weighted index comprised of the Bloomberg U.S. Long Credit Bond Index, Bloomberg U.S. Intermediate Credit Bond Index, Bloomberg U.S. Long Government Bond Index, Bloomberg U.S. Intermediate Government Bond Index, Bloomberg U.S. Securitized: MBS, ABS and CMBS Index, Bloomberg U.S. Treasury Inflation Protected Securities (TIPS) Index (Series-L), FTSE EPRA Nareit Developed Index, MSCI ACWI ex USA IMI Index, Russell 1000® Index and Russell 2000® Index, which are representative of the asset classes in which the Fund will invest.

Investment Adviser

The Fund's investment manager is BlackRock Fund Advisors (previously defined as "BFA").

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Portfolio Managers

Portfolio Manager

Portfolio Manager of the Fund Since Title

Chris Chung, CFA

2024 Managing Director of BlackRock, Inc.

Lisa O'Connor, CFA

2024 Managing Director of BlackRock, Inc.

Greg Savage, CFA

2024 Managing Director of BlackRock, Inc.

Paul Whitehead

2024 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 Intermediary, or, if you hold your shares through BlackRock, Inc. or its affiliates (collectively, "BlackRock"), you should contact BlackRock by phone at (800) 441-7762, by mail (c/o BlackRock Funds III, P.O. Box 534429, Pittsburgh, Pennsylvania 15253-4429), or by the Internet at www.blackrock.com. 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:

•  $50, if establishing an Automatic Investment Plan.

•  There is no investment minimum for employer-sponsored retirement plans (not including SEP IRAs, SIMPLE IRAs or SARSEPs).

•  There is no investment minimum for certain fee-based programs.

There is no minimum initial investment for:

•  Employer-sponsored retirement plans (not including SEP IRAs, SIMPLE IRAs or SARSEPs), state sponsored 529 college savings plans, collective trust funds, investment companies or other pooled investment vehicles, unaffiliated thrifts and unaffiliated banks and trust companies, each of which may purchase shares of the Fund through a Financial Intermediary that has entered into an agreement with the Fund's distributor to purchase such shares.

•  Clients of Financial Intermediaries that: (i) charge such clients a fee for advisory, investment consulting, or similar services or (ii) have entered into an agreement with the Fund's distributor to offer Institutional Shares through a no-load program or investment platform.

•  Clients investing through a self-directed IRA brokerage account program sponsored by a retirement plan record-keeper, provided that such program offers only mutual fund options and that the program maintains an account with the Fund on an omnibus basis.

$2 million for individuals and "Institutional Investors," which include, but are not limited to, endowments, foundations, family offices, local, city, and state governmental institutions, corporations and insurance company separate accounts who may purchase shares of the Fund through a Financial Intermediary that has entered into an agreement with the Fund's distributor to purchase such shares.

$1,000 for:

•  Clients investing through Financial Intermediaries that offer such shares on a platform that charges a transaction based sales commission outside of the Fund.

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Investor A Shares Institutional Shares

•  Tax-qualified accounts for insurance agents that are registered representatives of an insurance company's broker-dealer that has entered into an agreement with the Fund's distributor to offer Institutional Shares, and the family members of such persons.

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

Different income tax rules apply depending on whether you are invested through a qualified tax-exempt plan described in section 401(a) of the Internal Revenue Code. If you are invested through such a plan (and Fund shares are not "debt-financed property" to the plan), then the dividends paid by the Fund and the gain realized from a redemption or exchange of Fund shares will generally not be subject to U.S. federal income taxes until you withdraw or receive distributions from the plan. If you are not invested through such a plan, then the Fund's dividends and gain from a redemption or exchange 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.

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

SPRO-LPIND70-0924