April 12, 2017

2017 Summary Prospectus

^► iShares iBonds Dec 2023 Term Muni Bond ETF* | IBML | BATS

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://us.ishares.com/prospectus. You can also get this information at no cost by calling 1-800-iShares (1-800-474-2737) or by sending an e-mail request to iSharesETFs@blackrock.com, or from your financial professional. The Fund’s prospectus and statement of additional information, both dated March 27, 2017, as amended and supplemented from time to time, are incorporated by reference into (legally made a part of) this Summary Prospectus.

The Securities and Exchange Commission (“SEC”) has not approved or disapproved these securities or passed upon the adequacy of this prospectus. Any representation to the contrary is a criminal offense.

*The iShares iBonds Dec 2023 Term Muni Bond ETF may also conduct business as the iBonds Dec 2023 Term Muni Bond ETF.

iSHARES^® iBONDS^® DEC 2023 TERM MUNI BOND ETF

Ticker: IBML Stock Exchange: BATS

Investment Objective

The iShares iBonds Dec 2023 Term Muni Bond ETF (the “Fund”) seeks to track the investment results of an index composed of investment-grade U.S. municipal bonds maturing after December 31, 2022 and before December 2, 2023.

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 interest expenses, taxes, brokerage expenses, distribution fees or expenses, and extraordinary expenses.

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)
Management Fees	Distribution and Service (12b-1) Fees	Other Expenses	Total Annual Fund Operating Expenses
0.18%	None	None	0.18%

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:

1 Year	3 Years
$18	$58

S-1

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 Annual Fund Operating Expenses or in the Example, affect the Fund's performance.

Principal Investment Strategies

The Fund seeks to track the investment results of the S&P AMT-Free Municipal Series Dec 2023 Index^TM (the “Underlying Index”), which measures the performance of investment-grade, non-callable U.S. municipal bonds maturing in 2023. As of January 31, 2017, there were 5,488 issues in the Underlying Index.

The Underlying Index includes municipal bonds primarily from issuers that are state or local governments or agencies such that the interest on the bonds is exempt from U.S. federal income taxes. Each bond included in the Underlying Index must have a rating of at least BBB- by S&P Global Ratings, Baa3 by Moody’s Investors Service, Inc. (“Moody's”), or BBB- by Fitch Ratings, Inc., must have a minimum maturity par amount of $2 million, and must not be subject to the federal alternative minimum tax (“AMT”). To remain in the Underlying Index, bonds must maintain a minimum par amount greater than or equal to $2 million as of each rebalancing date. All bonds in the Underlying Index will mature after December 31, 2022 and before December 2, 2023. When a bond in the Underlying Index matures or is pre-

refunded, the bond does not accrue interest past the maturity or pre-refunded date. An amount representing its value at the time of maturity or pre-refunding will be included in the Underlying Index throughout the remaining life of the Underlying Index, and any such amount will be assumed to earn a rate equal to the tax-exempt return of cash and cash equivalents. The Underlying Index is a market value weighted index and is rebalanced after the market close on the last business day of each month.

The Fund is a series of the iShares iBonds^® fixed maturity series of bond exchange-traded funds sponsored by BlackRock, Inc. (“BlackRock”). The iBonds^® fixed maturity series do not invest in U.S. savings bonds or other U.S. government bonds and are not designed to provide protection against inflation.

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

S-2

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 an applicable underlying index.

The Fund generally will invest at least 90% of its assets in the component securities of the Underlying Index, except during the last months of the Fund's operations, as described below, and may invest up to 10% of its assets in certain futures, options and swap contracts, cash and cash equivalents, including shares of money market funds advised by BFA or its affiliates (“BlackRock Cash Funds”), as well as in securities not included in the Underlying Index, but which BFA believes will help the Fund track the Underlying Index. From time to time when conditions warrant, however, the Fund may invest at least 80% of its assets in the component securities of the Underlying Index, and may invest up to 20% of its assets in certain futures, options and swap contracts, cash and cash equivalents, including shares of BlackRock Cash Funds, as well as in securities not included in the Underlying Index, but which BFA believes will help the Fund track the Underlying Index. The Fund will generally hold municipal bond securities issued by state and local municipalities whose interest payments are exempt from U.S. federal income tax, the federal AMT and the

federal Medicare contribution tax of 3.8% on “net investment income,” including dividends, interest and capital gains. In the last months of operation, as the bonds held by the Fund mature, the proceeds will not be reinvested in bonds but instead will be held in cash and cash equivalents, including, without limitation, shares of BlackRock Cash Funds, AMT-free tax-exempt municipal notes, variable rate demand notes and obligations, tender option bonds and municipal commercial paper. These cash equivalents may not be included in the Underlying Index. By December 2, 2023, the Underlying Index is expected to consist entirely of cash earned in this manner. Around the same time, the Fund will wind up and terminate, and its net assets will be distributed to then-current shareholders. 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 a product of S&P Dow Jones Indices LLC (the “Index Provider” or “SPDJI”), 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

S-3

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.

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

Authorized Participant Concentration Risk. Only an Authorized Participant 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 and/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 and/or delisting.

Concentration Risk. The Fund may be susceptible to loss due to adverse events that affect the Fund’s investments more than the market as a whole, to the extent that the Fund's investments are concentrated in the securities of a particular state, region, municipality, market, project type, industry, group of industries, 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 the issuer’s or counterparty’s financial condition and on the terms of the securities.

S-4

Cyber Security Risk. Failures or breaches of the electronic systems of the Fund, the Fund's adviser, the Fund's distributor, and the Fund's 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.

Declining Yield Risk. During the final 11 months prior to the Fund's planned termination date, its yield will generally tend to move toward prevailing money market rates, and may be lower than the yields of the bonds previously held by the Fund and lower than prevailing yields for bonds in the market.

Fluctuation of Yield and Liquidation Amount Risk. The Fund, unlike a direct investment in a municipal bond that has a level coupon payment and a fixed payment at maturity, will make distributions of income that vary over time. It is expected that an investment in the Fund, if held through maturity, will produce aggregate returns comparable to a direct investment in a group of municipal bonds of similar credit quality and maturity. Unlike a direct investment in municipal bonds, the breakdown of returns between Fund distributions and liquidation proceeds are not predictable

at the time of your investment. For example, at times during the Fund's existence it may make distributions at a greater (or lesser) rate than the coupon payments received on the Fund's portfolio, which will result in the Fund returning a lesser (or greater) amount on liquidation than would otherwise be the case. The rate of Fund distribution payments may adversely affect the tax characterization of your returns from an investment in the Fund relative to a direct investment in municipal bonds. If the amount you receive as liquidation proceeds upon the Fund's termination is higher or lower than your cost basis, you may experience a gain or loss for tax purposes.

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 will achieve a high degree of correlation to the Underlying Index and therefore 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 and/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.

S-5

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 current historically low interest rate environment increases 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. The Fund invests in municipal bonds of issuers that are primarily state or local governments or agencies. Changes to 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. The Fund invests a significant portion of its portfolio in municipal securities, which may be less liquid than comparable taxable bonds.

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.

Municipal Securities Risk. Municipal securities can be significantly affected by political or economic changes as well as uncertainties in the municipal market related to taxation, legislative changes or the rights of municipal security holders, including in connection with an issuer insolvency. Municipal securities backed by current or anticipated revenues from a specific project or specific assets can be negatively affected by the inability to collect revenues for the project or from the assets. In the event of a default or insolvency, certain issuers of municipal bonds may be subject to proceedings other than those specified by U.S. bankruptcy laws, which may impact the Fund’s ability to ultimately recover assets.

Non-Diversification Risk. The Fund may invest a large percentage of its assets in securities issued by or representing a small number of issuers. As a result, the Fund's performance may depend on the performance of a small number of issuers.

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

S-6

address every possible risk and may be inadequate to address these 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.

Risk of Investing in the United States. The Fund has significant exposure to U.S. issuers. 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.

School District Investment Risk.School districts rely, in part, on funding appropriations from, among others, the federal government and state governments. As a result, municipal securities issued by school districts may be adversely affected by political and economic changes at the state or federal levels, such as decreased tax or other revenues, spending reductions or changes in appropriations. Municipal securities that are issued to finance a particular school district project often depend on revenues from that project to make principal and interest payments. Adverse conditions and developments affecting a particular project can result in lower revenues to the issuer of the municipal securities.

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. Substitute payments received by the Fund with respect to municipal securities lent, if any, will not constitute tax-exempt interest income to the Fund.

Tax Risk. There is no guarantee that the Fund's income will be exempt from U.S. federal income taxes, the federal AMT or the federal Medicare contribution tax of 3.8% on “net investment income.”

Tracking Error Risk. Tracking error is the divergence of a fund’s performance from that of the applicable 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 applicable underlying index, pricing differences, differences in transaction costs, the fund’s holding of uninvested cash, differences in timing of the accrual of or the valuation of dividends or interest, tax gains or losses, changes to the applicable 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 a fund incurs fees and expenses, while the applicable underlying index does not.

Utilities Sector Risk. Municipal securities that are issued to finance a particular utility project often depend on revenues from that project to make principal and interest payments. The utilities sector is subject to significant government regulation and oversight, and may be adversely affected by increases in fuel and operating costs, rising costs of financing capital construction and the cost of complying

S-7

with U.S. federal and state regulations, among other factors.

Valuation Risk. The sale price the Fund could receive for a security may differ from the Fund's valuation of the security or asset and from the value used by the Underlying Index, particularly for securities or assets that trade in low volume or volatile markets or that are valued using a fair value methodology.

Because the bond market may be open on days or during time periods when the Fund does not price its shares, the value of the securities or assets in the Fund’s portfolio may change on days or during time periods when shareholders will not be able to purchase or sell the Fund’s shares.

S-8

Performance Information

As of the date of the Prospectus, the Fund has been in operation for less than one full calendar year and therefore does not report its performance information.

Management

Investment Adviser. BlackRock Fund Advisors.

Portfolio Managers. James Mauro and Scott Radell (the “Portfolio Managers”) are primarily responsible for the day-to-day management of the Fund. Each Portfolio Manager supervises a portfolio management team. Mr. Mauro and Mr. Radell have been Portfolio Managers of the Fund since inception.

Purchase and Sale of Fund Shares

The Fund is an exchange-traded fund (commonly referred to as an “ETF”). Individual shares of the Fund are listed on a national securities exchange. Most investors will buy and sell shares of the Fund through a broker-dealer. The price of Fund shares is based on market price, and because ETF shares trade at market prices rather than at NAV, shares may trade at a price greater than NAV (a premium) or less than NAV (a discount). The Fund will only issue or redeem shares that have been aggregated into blocks of 50,000 shares or multiples thereof (“Creation Units”) to Authorized Participants who have entered into agreements with the Fund's distributor. The Fund generally will issue or redeem Creation Units in return for a designated portfolio of securities (and an amount of cash) that the Fund specifies each day.

Tax Information

The Fund intends to make distributions primarily from net tax-exempt income, although distributions of taxable capital gains may also occur. The Fund is generally not an appropriate investment for a 401(k) plan or an individual retirement account (“IRA”). Please consult your personal tax adviser.

Payments to Broker-Dealers and other Financial Intermediaries

If you purchase shares of the Fund through a broker-dealer or other financial intermediary (such as a bank), BFA or other related companies may pay the intermediary for marketing activities and presentations, educational training programs, conferences, the development of technology platforms and reporting systems or other services related to the sale or promotion of the Fund. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your salesperson to recommend the Fund over another investment. Ask your salesperson or visit your financial intermediary’s website for more information.

S-9

[THIS PAGE INTENTIONALLY LEFT BLANK]

For more information visit www.iShares.com or call 1-800-474-2737

IS-SP-IBML-0317

Investment Company Act file No.: 811-09729