iShares Core U.S. Aggregate Bond ETF

iSHARES^® CORE U.S. AGGREGATE BOND ETF
Ticker: AGG                                 Stock Exchange: NYSE Arca

Investment Objective

The iShares Core U.S. Aggregate Bond ETF (the “Fund”) seeks to track the investment results of an index composed of the total U.S. investment-grade bond market.

Fees and Expenses

The following table describes the fees and expenses that you will incur if you own shares of the Fund. The investment advisory agreement between iShares Trust (the “Trust”) and BlackRock Fund Advisors (“BFA”) (the “Investment Advisory Agreement”) provides that BFA will pay all operating expenses of the Fund, except the management fees, interest expenses, taxes, expenses incurred with respect to the acquisition and disposition of portfolio securities and the execution of portfolio transactions, including brokerage commissions, distribution fees or expenses, litigation expenses and any extraordinary expenses. The Fund may incur “Acquired Fund Fees and Expenses.” Acquired Fund Fees and Expenses reflect the Fund's pro rata share of the fees and expenses incurred by investing in other investment companies. The impact of Acquired Fund Fees and Expenses is included in the total returns of the Fund. Acquired Fund Fees and Expenses are not included in the calculation of the ratio of expenses to average net assets shown in the Financial Highlights section of the Fund's prospectus (the “Prospectus”). BFA, the investment adviser to the Fund, has contractually agreed to waive a portion of its management fees in an amount equal to the Acquired Fund Fees and Expenses, if any, attributable to investments by the Fund in other registered investment companies advised by BFA or its affiliates, through June 30, 2026. The contractual waiver may be terminated prior to June 30, 2026 only upon written agreement of the Trust and BFA.

You may also incur usual and customary brokerage commissions and other charges when buying or selling shares of the Fund, which are not reflected in the Example that follows:

Annual Fund Operating Expenses
(ongoing expenses that you pay each year as a
percentage of the value of your investments)

Annual Fund Operating Expenses	Management Fees	Distribution and Service (12b-1) Fees	Other Expenses	Acquired Fund Fees and Expenses	Total Annual Fund Operating Expenses	Fee Waiver	Total Annual Fund Operating Expenses After Fee Waiver
iShares Core U.S. Aggregate Bond ETF | iShares Core U.S. Aggregate Bond ETF	0.05%	none	none	0.01%	0.06%	(0.01%)	0.05%

Example.

This Example is intended to help you compare the cost of owning shares of the Fund with the cost of investing in other funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell 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:

Expense Example	1 Year	3 Years	5 Years	10 Years
iShares Core U.S. Aggregate Bond ETF | iShares Core U.S. Aggregate Bond ETF | USD ($)	5	16	28	67

Portfolio Turnover.

The Fund may pay transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in the Annual Fund Operating Expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 252% of the average value of its portfolio.

Principal Investment Strategies

The Fund seeks to track the investment results of the Bloomberg Barclays U.S. Aggregate Bond Index (the “Underlying Index”), which measures the performance of the total U.S. investment-grade (as determined by Bloomberg Index Services Limited (the “Index Provider” or “Bloomberg”)) bond market. As of February 28, 2018, there were 9,826 issues in the Underlying Index.

The Underlying Index includes investment-grade U.S. Treasury bonds, government-related bonds, corporate bonds, mortgage-backed pass-through securities (“MBS”), commercial mortgage-backed securities (“CMBS”) and asset-backed securities (“ABS”) that are publicly offered for sale in the U.S. As of February 28, 2018, a significant portion of the Underlying Index is represented by MBS and treasury securities, and securities of companies in the industrials sector. The components of the Underlying Index, and the degree to which these components represent certain sectors, are likely to change over time.

The securities in the Underlying Index must have $300 million or more of outstanding face value and must have at least one year remaining to maturity, with the exception of amortizing securities such as ABS and MBS, which have lower thresholds as defined by Bloomberg. In addition, the securities in the Underlying Index must be denominated in U.S. dollars and must be fixed-rate and non-convertible. Certain types of securities, such as state and local government series bonds, structured notes with embedded swaps or other special features, private placements, floating-rate securities and bonds that have been issued in one country's currency but are traded outside of that country in a different monetary and regulatory system (Eurobonds), are excluded from the Underlying Index. The Underlying Index is market capitalization-weighted, and the securities in the Underlying Index are updated on the last business day of each month.

As of February 28, 2018, approximately 28.22% of the bonds represented in the Underlying Index were U.S. fixed-rate agency MBS. U.S. fixed-rate agency MBS are securities issued by entities such as the Government National Mortgage Association (“Ginnie Mae”), the Federal National Mortgage Association (“Fannie Mae”), and the Federal Home Loan Mortgage Corporation (“Freddie Mac”) and are backed by pools of mortgages. Most transactions in fixed-rate MBS occur through standardized contracts for future delivery in which the exact mortgage pools to be delivered are not specified until a few days prior to settlement (to-be-announced (“TBA”) transactions). The Fund may enter into such contracts on a regular basis. The Fund, pending settlement of such contracts, will invest its assets in high-quality, liquid short-term instruments, including shares of money market funds advised by BFA or its affiliates. The Fund will assume its pro rata share of the fees and expenses of any money market fund that it may invest in, in addition to the Fund's own fees and expenses. The Fund may also acquire interests in mortgage pools through means other than such standardized contracts for future delivery.

BFA uses a “passive” or indexing approach to try to achieve the Fund’s investment objective. Unlike many investment companies, the Fund does not try to “beat” the index it tracks and does not seek temporary defensive positions when markets decline or appear overvalued.

Indexing may eliminate the chance that the Fund will substantially outperform the Underlying Index but also may reduce some of the risks of active management, such as poor security selection. Indexing seeks to achieve lower costs and better after-tax performance by keeping portfolio turnover low in comparison to actively managed investment companies.

BFA uses a representative sampling indexing strategy to manage the Fund. “Representative sampling” is an indexing strategy that involves investing in a representative sample of securities that collectively has an investment profile similar to that of an applicable underlying index. The securities selected are expected to have, in the aggregate, investment characteristics (based on factors such as market capitalization and industry weightings), fundamental characteristics (such as return variability, duration, maturity, credit ratings and yield) and liquidity measures similar to those of an applicable underlying index. The Fund may or may not hold all of the securities in the Underlying Index.

The Fund generally seeks to track the performance of the Underlying Index by investing at least 90% of its net assets in component securities of its Underlying Index and in investments that have economic characteristics that are substantially identical to the economic characteristics of the component securities of its Underlying Index (i.e., TBAs). The Fund may invest up to 10% of its portfolio in bonds not included in the Underlying Index, but which BFA believes will help the Fund track the Underlying Index, as well as in certain futures, options and swap contracts, cash and high-quality, liquid short-term instruments, including shares of money market funds advised by BFA or its affiliates. The Fund seeks to track the investment results of the Underlying Index before fees and expenses of the Fund.

The Fund may lend securities representing up to one-third of the value of the Fund's total assets (including the value of any collateral received).

The Underlying Index is sponsored by Bloomberg, which is independent of the Fund and BFA. The Index Provider determines the composition and relative weightings of the securities in the Underlying Index and publishes information regarding the market value of the Underlying Index.

Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated. For purposes of this limitation, securities of the U.S. government (including its agencies and instrumentalities), repurchase agreements collateralized by U.S. government securities, and securities of state or municipal governments and their political subdivisions are not considered to be issued by members of any industry.

Summary of Principal Risks

As with any investment, you could lose all or part of your investment in the Fund, and the Fund's performance could trail that of other investments. The Fund is subject to certain risks, including the principal risks noted below, any of which may adversely affect the Fund's net asset value per share (“NAV”), trading price, yield, total return and ability to meet its investment objective.

Asset Class Risk. Securities and other assets in the Underlying Index or in the 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 the Fund. The Fund has a limited number of institutions that may act as Authorized Participants on an agency basis (i.e., on behalf of other market participants). To the extent that Authorized Participants exit the business or are unable to proceed with creation or redemption orders with respect to the Fund and no other Authorized Participant is able to step forward to create or redeem Creation Units (as defined in the Purchase and Sale of Fund Shares section of the Prospectus), Fund shares may be more likely to trade at a premium or discount to NAV and possibly face trading halts or delisting.

Call Risk. During periods of falling interest rates, an issuer of a callable bond held by the Fund may “call” or repay the security before its stated maturity, and the Fund may have to reinvest the proceeds in securities with lower yields, which would result in a decline in the Fund's income, or in securities with greater risks or with other less favorable features.

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

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

Cyber Security Risk. Failures or breaches of the electronic systems of the Fund, the Fund's adviser, distributor, and other service providers, market makers, Authorized Participants or the issuers of securities in which the Fund invests have the ability to cause disruptions and negatively impact the Fund’s business operations, potentially resulting in financial losses to the Fund and its shareholders. While the Fund has established business continuity plans and risk management systems seeking to address system breaches or failures, there are inherent limitations in such plans and systems. Furthermore, the Fund cannot control the cyber security plans and systems of the Fund’s service providers, the Index Provider, market makers, Authorized Participants or issuers of securities in which the Fund invests.

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

Geographic Risk. A natural disaster could occur in a geographic region in which the Fund invests, which could adversely affect the economy or the business operations of companies in the specific geographic region, causing an adverse impact on the Fund's investments in the affected region.

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

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

Index-Related Risk. There is no guarantee that the Fund’s investment results will have a high degree of correlation to those of the Underlying Index or that the Fund will achieve its investment objective. Market disruptions and regulatory restrictions could have an adverse effect on the Fund’s ability to adjust its exposure to the required levels in order to track the Underlying Index. Errors in index data, index computations or the construction of the 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 the Fund and its shareholders.

Industrials Sector Risk. Companies in the industrials sector may be adversely affected by changes in the supply of and demand for products and services, product obsolescence, claims for environmental damage or product liability and changes in general economic conditions, among other factors.

Interest Rate Risk. An increase in interest rates may cause the value of securities held by the Fund to decline, may lead to heightened volatility in the fixed-income markets and may adversely affect the liquidity of certain fixed-income investments. The historically low interest rate environment, together with recent modest rate increases, heightens the risks associated with rising interest rates.

Issuer Risk. The performance of the Fund 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.

Liquidity Risk. Liquidity risk exists when particular investments are difficult to purchase or sell. This can reduce the Fund's returns because the Fund may be unable to transact at advantageous times or prices.

Management Risk. As the Fund may not fully replicate the Underlying Index, it is subject to the risk that BFA's investment strategy may not produce the intended results.

Market Risk. The Fund could lose money over short periods due to short-term market movements and over longer periods during more prolonged market downturns.

Market Trading Risk. The Fund faces numerous market trading risks, including the potential lack of an active market for Fund shares, losses from trading in secondary markets, periods of high volatility and disruptions in the creation/redemption process. ANY OF THESE FACTORS, AMONG OTHERS, MAY LEAD TO THE FUND'S SHARES TRADING AT A PREMIUM OR DISCOUNT TO NAV.

Mortgage-Backed Securities Risk. The Fund invests in  MBS, some of which may not be backed by the full faith and credit of the U.S. government. MBS are subject to prepayment or call risk and extension risk. Because of these risks, MBS react differently than other bonds to changes in interest rates. Small movements in interest rates (both increases and decreases) may quickly and significantly reduce the value of certain MBS. Default or bankruptcy of a counterparty to a TBA transaction would expose the Fund to possible loss.

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

Passive 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.

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

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.

Securities Lending Risk. The Fund may engage in securities lending. Securities lending involves the risk that the Fund may lose money because the borrower of the loaned securities fails to return the securities in a timely manner or at all. The Fund could also lose money in the event of a decline in the value of collateral provided for loaned securities or a decline in the value of any investments made with cash collateral. These events could also trigger adverse tax consequences for the Fund.

Sovereign and Quasi-Sovereign Obligations Risk. The Fund invests in securities issued by or guaranteed by sovereign governments and by entities affiliated with or backed by non-U.S. sovereign governments, which may be unable or unwilling to repay principal or interest when due. In times of economic uncertainty, the prices of these securities may be more volatile than those of corporate debt obligations or of other government debt obligations.

Tracking Error Risk. The Fund may be subject to tracking error, which is the divergence of the Fund’s performance from that of the Underlying Index. Tracking error may occur because of differences between the securities and other instruments held in the Fund’s portfolio and those included in the Underlying Index, pricing differences (including, as applicable, differences between a security’s price at the local market close and the Fund's valuation of a security at the time of calculation of the Fund's NAV), differences in transaction costs, the Fund’s holding of uninvested cash, differences in timing of the accrual of or the valuation of distributions, tax gains or losses, changes to the Underlying Index or the costs to the Fund of complying with various new or existing regulatory requirements. This risk may be heightened during times of increased market volatility or other unusual market conditions. Tracking error also may result because the Fund incurs fees and expenses, while the Underlying Index does not.

U.S. Agency Debt Risk. The Fund invests in unsecured bonds or debentures issued by U.S. government agencies. Bonds or debentures issued by U.S. government agencies, government-sponsored entities, or government corporations, including, among others, Fannie Mae and Freddie Mac, are generally backed only by the general creditworthiness and reputation of the U.S. government agency, government-sponsored entity, or government corporation issuing the bond or debenture and are not guaranteed by the U.S. Department of the Treasury (“U.S. Treasury”) or backed by the full faith and credit of the U.S. government. As a result, there is uncertainty as to the current status of many obligations of Fannie Mae, Freddie Mac and other agencies that are placed under conservatorship of the U.S. government. Ginnie Mae securities are generally backed by the full faith and credit of the U.S. government.

U.S. Treasury Obligations Risk. U.S. Treasury obligations may differ from other securities in their interest rates, maturities, times of issuance and other characteristics and may provide relatively lower returns than those of other securities. Similar to other issuers, changes to the financial condition or credit rating of the U.S. government may cause the value of the Fund's U.S. Treasury obligations to decline.

Performance Information

The bar chart and table that follow show how the Fund has performed on a calendar year basis and provide an indication of the risks of investing in the Fund. Both assume that all dividends and distributions have been reinvested in the Fund. Past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Supplemental information about the Fund’s performance is shown under the heading Total Return Information in the Supplemental Information section of the Prospectus. If BFA had not waived certain Fund fees during certain periods, the Fund's returns would have been lower.

Year by Year Returns (Years Ended December 31)

The best calendar quarter return during the periods shown above was 5.21% in the 4th quarter of 2008; the worst was -3.00% in the 4th quarter of 2016.

Updated performance information may be obtained by visiting our website at www.iShares.com or by calling 1-800-iShares (1-800-474-2737) (toll free).

Average Annual Total Returns
(for the periods ended December 31, 2017)

Average Annual Total Returns - iShares Core U.S. Aggregate Bond ETF		One Year	Five Years	Ten Years	Inception Date
iShares Core U.S. Aggregate Bond ETF		3.53%	2.05%	3.90%	Sep. 22, 2003
iShares Core U.S. Aggregate Bond ETF | Return After Taxes on Distributions	[1]	2.49%	1.02%	2.71%
iShares Core U.S. Aggregate Bond ETF | Return After Taxes on Distributions and Sale of Fund Shares	[1]	1.99%	1.09%	2.54%
Bloomberg Barclays U.S. Aggregate Bond Index (Index returns do not reflect deductions for fees, expenses, or taxes)		3.54%	2.10%	4.01%

[1] The Fund’s year-to-date return as of March 31, 2018 was -1.49%.

[1] After-tax returns in the table above are calculated using the historical highest individual U.S. federal marginal income tax rates and do not reflect the impact of state or local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown, and after-tax returns shown are not relevant to tax-exempt investors or investors who hold shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts (“IRAs”). Fund returns after taxes on distributions and sales of Fund shares are calculated assuming that an investor has sufficient capital gains of the same character from other investments to offset any capital losses from the sale of Fund shares. As a result, Fund returns after taxes on distributions and sales of Fund shares may exceed Fund returns before taxes and/or returns after taxes on distributions.