Form 485BPOS

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.


Fund Overview	S-1
More Information About the Fund	1
A Further Discussion of Principal Risks	2
Portfolio Holdings Information	7
Management	7
Shareholder Information	10
Distribution	18
Financial Highlights	19
Index Provider	20
Disclaimers	20
Supplemental Information	22

“Standard & Poor’s^®,” “S&P^®” and “S&P AMT-Free Municipal Series 2012 Index^TM” are trademarks of Standard & Poor’s Financial Services LLC (a subsidiary of The McGraw-Hill Companies) licensed for use for certain purposes by BlackRock Institutional Trust Company, N.A. (“BTC”). iShares^® is a registered trademark of BTC.

The iShares 2012 S&P AMT-Free Municipal Series (the “Fund”) seeks investment results that correspond generally to the price and yield performance, before fees and expenses, of the S&P AMT-Free Municipal Series 2012 Index^TM (the “Underlying Index”). The Fund does not seek to return any predetermined amount at maturity.

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

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:

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. During the most recent fiscal year, the Fund’s portfolio turnover rate was 2% of the average value of its portfolio.

The Underlying Index measures the performance of investment-grade U.S. municipal bonds maturing in 2012. As of May 31, 2011, there were 3,522 issues in the Underlying Index.

The Underlying Index includes municipal bonds primarily from issuers that are state or local governments or agencies (including the Commonwealth of Puerto Rico and U.S. territories such as the U.S. Virgin Islands and Guam) such that the interest on the bonds is exempt from U.S. federal income taxes and the federal alternative minimum tax (“AMT”). Each bond must have a rating of at least BBB- by Standard & Poor’s Financial Services LLC (a subsidiary of The McGraw-Hill Companies) (“S&P”), Baa3 by Moody’s Investors Service, Inc. (“Moody’s”), or BBB- by Fitch, Inc. and must have a minimum maturity par amount of $2 million to be eligible for inclusion in the Underlying Index. 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 between June 1 and August 31 of the year referenced in the name of the Underlying Index. When a bond matures in the Underlying Index, an amount representing its value at maturity 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 performance of the S&P’s Weekly High Grade Index, which consists of Moody’s Investment Grade-1 municipal tax-exempt notes that are not subject to AMT. By August 31, 2012, the Underlying Index is expected to consist entirely of cash carried in this manner. The Underlying Index is a market value weighted index and is rebalanced after the close on the last business day of each month.

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.

The Fund generally invests at least 80% of its assets in the securities of its Underlying Index, except during the last months of the Fund’s operations, as described below. The Fund may at times invest up to 20% of its assets in cash and cash equivalents (including money market funds affiliated with BFA), as well as in municipal bonds not included in the Underlying Index, but which BFA believes will help the Fund track its Underlying Index. For example, the Fund may invest in municipal bonds not included in the Underlying Index in order to reflect prospective changes in the Underlying Index (such as index reconstitutions, additions and deletions). 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, effective beginning in 2013, a federal Medicare contribution tax of 3.8% on “net investment income,” including dividends, interest and capital gains. In addition, the Fund may invest any cash assets in one or more affiliated municipal money market funds. 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 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. On or about August 31, 2012, the Fund will wind up and terminate, and its net assets will be distributed to then-current shareholders.

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

The Underlying Index is sponsored by an organization (the “Index Provider”) that 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. The Fund’s Index Provider is S&P.

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.

Asset Class Risk. Securities in the Underlying Index or in the Fund’s portfolio may underperform in comparison to the general securities markets or other asset classes.

Concentration Risk. To the extent that the Fund’s investments are concentrated in a particular state, region, market, project type or asset class, the Fund may be susceptible to loss due to adverse occurrences affecting that state, region, market, project type or asset class.

Credit Risk. The Fund is subject to the risk that debt issuers and other counterparties may not honor their obligations.

Declining Yield Risk. During the final three months prior to the Fund’s planned termination date, its yield will generally tend to move toward prevailing tax-exempt 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 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.

Interest Rate Risk. An increase in interest rates may cause the value of fixed-income securities held by the Fund to decline.

Issuer Risk. Fund performance 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 taxable bonds.

Market Risk. The Fund could lose money over short periods due to short-term market movements and over longer periods during market downturns. The recent financial crisis has caused a decrease in the value and liquidity of many securities, including municipal securities, and has adversely affected many issuers of municipal securities and may continue to do so.

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 disruption in the creation/redemption process of the Fund. 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. 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.

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.

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

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 Fund’s 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 the 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.

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” (effective beginning in 2013).

As of the date of the Fund’s prospectus (the “Prospectus”), the Fund has been in operation for less than one full calendar year and therefore does not report its performance information.

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 2011 and 2010, respectively.

The Fund is an exchange-traded fund (commonly referred to as an “ETF”). Individual Fund shares may only be purchased and sold on a national securities exchange through a broker-dealer. The price of Fund shares is based on market price, and because ETF shares trade at market prices rather than 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 will issue or redeem Creation Units in return for a basket of assets that the Fund specifies each day.

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 advisor.

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.

This Prospectus contains important information about investing in the Fund. Please read this Prospectus carefully before you make any investment decisions. Additional information regarding the Fund is available at www.iShares.com.

BFA is the investment adviser to the Fund. Shares of the Fund are listed for trading on NYSE Arca, Inc. (“NYSE Arca”). The market price for a share of the Fund may be different from the Fund’s most recent NAV.

ETFs are funds that trade like other publicly-traded securities. The Fund is designed to track an index. Similar to shares of an index mutual fund, each share of the Fund represents a partial ownership in an underlying portfolio of securities intended to track a market index. Unlike shares of a mutual fund, which can be bought and redeemed from the issuing fund by all shareholders at a price based on NAV, shares of the Fund may be purchased or redeemed directly from the Fund at NAV solely by authorized participants. Also unlike shares of a mutual fund, shares of the Fund are listed on a national securities exchange and trade in the secondary market at market prices that change throughout the day.

The Fund will wind up and terminate on or about August 31, 2012. Upon its termination, the Fund will distribute substantially all of its net assets, after making appropriate provision for any liabilities of the Fund, to then-current shareholders pursuant to a plan of liquidation. In the final months of the Fund’s operation, as the bonds it holds mature, its portfolio will transition to cash and cash-like instruments, including without limitation AMT-free tax-exempt municipal notes, variable rate demand notes and obligations, tender option bonds and municipal commercial paper. In accordance with the Trust’s Amended and Restated Declaration of Trust dated September 17, 2009, the Fund will terminate on the date above as approved by a majority of the Trust’s Board of Trustees (the “Board”) without requiring additional approval by Fund shareholders. The Board may extend the termination date if a majority of the Board determines the extension to be in the best interest of the Fund.

The Fund invests in a particular segment of the securities markets and seeks to track the performance of a securities index that generally is not representative of the market as a whole. The Fund is designed to be used as part of broader asset allocation strategies. Accordingly, an investment in the Fund should not constitute a complete investment program.

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, BFA or any of its affiliates.

The Fund’s investment objective and the Underlying Index may be changed without shareholder approval.

The Fund is subject to various risks, including the principal risks noted below, any of which may adversely affect the Fund’s NAV, trading price, yield, total return and ability to meet its investment objective. You could lose all or part of your investment in the Fund, and the Fund could underperform other investments.

Asset Class Risk. The securities in the Underlying Index or in the Fund’s portfolio may underperform the returns of other securities or indexes that track other countries, regions, industries, groups of industries, markets, asset classes or sectors. Various types of securities or indexes tend to experience cycles of outperformance and underperformance in comparison to the general securities markets.

Concentration Risk. To the extent that the Fund’s portfolio reflects the Underlying Index’s concentration in the securities of issuers in a particular state, region, market, project type, sector or asset class, the 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 state, region, market, project type, sector or asset class.

Credit Risk. Credit risk is the risk that an issuer or guarantor of debt instruments or the counterparty to a derivatives contract, repurchase agreement or loan of portfolio securities will be unable or unwilling to make their timely interest and/or principal payments or to otherwise honor its obligations. Debt instruments are subject to varying degrees of credit risk, which may be reflected in their credit ratings. There is the chance that any of the Fund’s portfolio holdings will have their credit ratings downgraded or will default (fail to make scheduled interest or principal payments), potentially reducing the Fund’s income level or share price. Because the Fund holds a portfolio of securities set to mature at approximately the same time, the Fund generally will have greater exposure to interest rate risk earlier in its life than closer to its termination date.

Declining Yield Risk. During the final three months prior to the planned termination date of the Fund, the bonds held by the Fund will mature and the Fund’s portfolio will convert to cash or cash equivalents. During these final three months, the Fund’s yield will generally tend to move toward prevailing tax-exempt 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 municipal bonds of similar credit quality and maturity, but unlike a direct investment in municipal bonds, the breakdown of returns between Fund distributions and liquidation proceeds will not be predictable at the time of your investment. The Fund 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 breakdown between Fund distribution payments and the amount of liquidation proceeds 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. In addition, the yield on your investment (i.e., your purchase price) may be lower (or higher) than the Fund’s published yields, which are based on the Fund’s NAV.

Interest Rate Risk. As interest rates rise, the value of a fixed-income security held by the Fund is likely to decrease. Securities with longer durations tend to be more sensitive to interest rate changes, usually making them more volatile than securities with shorter durations. To the extent the Fund invests a substantial portion of its assets in fixed-income securities with longer-term maturities, rising interest rates may cause the value of the Fund’s investments to decline significantly. Because the Fund holds a portfolio of securities set to mature at approximately the same time, the Fund generally will have greater exposure to interest rate risk earlier in its life than closer to its termination date.

Issuer Risk. Changes in the financial condition of an issuer or counterparty, changes in specific economic or political conditions that affect a particular type of security or issuer, and changes in general economic or political conditions can affect a security’s or instrument’s credit quality or value.

Liquidity Risk. Liquidity risk exists when particular investments are difficult to purchase or sell. If the Fund invests in illiquid securities or securities that become illiquid, it may reduce the returns of the Fund because the Fund may be unable to sell the illiquid securities at an advantageous time or price.

The market for municipal bonds may be less liquid than for taxable bonds. There may also be less information available on the financial condition of issuers of municipal securities than for public corporations. This means that it may be harder to buy and sell municipal securities, especially on short notice, and municipal securities may be more difficult for the Fund to value accurately than securities of public corporations. Since the Fund invests a significant portion of its portfolio in municipal securities, the Fund’s portfolio may have greater exposure to liquidity risk than a fund that invests in non-municipal securities.

Management Risk. The Fund does not fully replicate the Underlying Index and may hold securities not included in the Underlying Index. As a result, the Fund is subject to

Market Risk. The Fund could lose money due to short-term market movements and over longer periods during market downturns. Securities may decline in value due to factors affecting securities markets generally or particular industries represented in the markets. The value of a security may decline due to general market conditions, economic trends or events that are not specifically related to the issuer of the security or to factors that affect a particular project type or types. During a general downturn in the securities markets, multiple asset classes may be negatively affected. Fixed-income securities with short-term maturities are generally less sensitive to such changes than fixed-income securities with longer-term maturities.

Recently, the equity and debt capital markets in the United States and internationally have experienced unprecedented volatility. This financial crisis has caused a significant decline in the value and liquidity of many securities, including municipal securities, and has adversely affected many issuers of municipal securities and may continue to do so. Changes in market conditions will not have the same impact on all types of securities. The value of a security may also decrease due to specific conditions that affect a particular sector of the securities market or a particular issuer. In addition, since many municipal securities are issued to finance similar projects, such as those relating to education, health care, housing, utilities, and water and sewer, conditions in these industries can affect the overall municipal market.

Absence of Active Market. Although shares of the Fund are listed for trading on one or more stock exchanges, there can be no assurance that an active trading market for such shares will develop or be maintained.

Risk of Secondary Listings. The Fund’s shares may be listed or traded on U.S. and non-U.S. stock exchanges other than the U.S. stock exchange where the Fund’s primary listing is maintained. There can be no assurance that the Fund’s shares will continue to trade on any such stock exchange or in any market or that the Fund’s shares will continue to meet the requirements for listing or trading on any exchange or in any market. The Fund’s shares may be less actively traded in certain markets than others, and investors are subject to the execution and settlement risks and market standards of the market where they or their broker direct their trades for execution. Certain information available to investors who trade Fund shares on a U.S. stock exchange during regular U.S. market hours may not be available to investors who trade in other markets, which may result in secondary market prices in such markets being less efficient.

Secondary Market Trading Risk. Shares of the Fund may trade in the secondary market at times when the Fund does not accept orders to purchase or redeem shares. At such times, shares may trade in the secondary market with more significant premiums or discounts than might be experienced at times when the Fund accepts purchase and redemption orders.

Secondary market trading in Fund shares may be halted by a stock exchange because of market conditions or other reasons. In addition, trading in Fund shares on a stock

Shares of the Fund May Trade at Prices Other Than NAV. Shares of the Fund trade on stock exchanges at prices at, above or below their most recent NAV. The NAV of the Fund is calculated at the end of each business day and fluctuates with changes in the market value of the Fund’s holdings since the most recent calculation. The trading prices of the Fund’s shares fluctuate continuously throughout trading hours based on market supply and demand rather than NAV. The trading prices of the Fund’s shares may deviate significantly from NAV during periods of market volatility. ANY OF THESE FACTORS, AMONG OTHERS, MAY LEAD TO THE FUND’S SHARES TRADING AT A PREMIUM OR DISCOUNT TO NAV. However, because shares can be created and redeemed in Creation Units at NAV (unlike shares of many closed-end funds, which frequently trade at appreciable discounts from, and sometimes at premiums to, their NAVs), BFA believes that large discounts or premiums to the NAV of the Fund are not likely to be sustained over the long-term. While the creation/redemption feature is designed to make it likely that the Fund’s shares normally will trade on stock exchanges at prices close to the Fund’s next calculated NAV, exchange prices are not expected to correlate exactly with the Fund’s NAV due to timing reasons as well as market supply and demand factors. In addition, disruptions to creations and redemptions or extreme market volatility may result in trading prices for shares of the Fund that differ significantly from their NAV.

Costs of Buying or Selling Fund Shares. Buying or selling Fund shares on an exchange involves two types of costs that apply to all securities transactions. When buying or selling shares of the Fund through a broker, you will likely incur a brokerage commission or other charges imposed by brokers as determined by that broker. In addition, you may incur the cost of the “spread” – that is, the difference between what investors are willing to pay for Fund shares (the “bid” price) and the price at which they are willing to sell Fund shares (the “ask” price). Because of the costs inherent in buying or selling Fund shares, frequent trading may detract significantly from investment results and an investment in Fund shares may not be advisable for investors who anticipate regularly making small investments.

Municipal Securities Risk. Municipal securities are subject to the risk that litigation, legislation or other political events, local business or economic conditions or the bankruptcy of the issuer could have a significant effect on an issuer’s ability to make payments of principal and/or interest or otherwise affect the value of such securities.

Municipal securities can be significantly affected by political changes as well as uncertainties in the municipal market related to taxation, legislative changes or the rights of municipal security holders. Because many municipal securities are issued to finance similar projects, especially those relating to education, health care, transportation and utilities, conditions in those sectors can affect the overall municipal market. In addition, changes in the financial condition of an individual municipal insurer can affect the overall municipal market.

Municipal securities backed by current or anticipated revenues from a specific project

Non-Diversification Risk. The Fund is classified as “non-diversified.” This means that 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 may be more susceptible to the risks associated with these particular issuers, or to a single economic, political or regulatory occurrence affecting these issuers.

Passive Investment Risk. The Fund is not actively managed and may be affected by a general decline in bond market segments related to the Underlying Index. The Fund invests in securities included in, or representative of, the Underlying Index regardless of their investment merits. BFA does not attempt to take defensive positions under any market conditions, including declining markets.

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 Fund’s 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 the collateral provided for the 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 AMT or the federal Medicare contribution tax of 3.8% on “net investment income” (effective beginning in 2013). The Index Provider relies on the bond issuer’s prospectus disclosure of the opinion from its counsel as to the tax-exempt status of the investment. Similarly, for municipal bonds not represented in the Underlying Index, BFA relies on prospectus disclosure of the tax opinion from the bond issuer’s counsel. Neither BFA nor the Fund guarantees that these opinions are correct, and there is no assurance that the Internal Revenue Service (“IRS”) will agree with the bond counsel’s tax opinion. Issuers or other parties generally enter into covenants requiring continuing compliance with U.S. federal tax requirements to preserve the tax-free status of interest payments over the life of the security. If at any time the covenants are not complied with, or if the IRS otherwise determines that the issuer did not comply with relevant tax requirements, interest payments from a security could become federally taxable, possibly retroactively to the date the security was issued, and the security could decline significantly in value. For municipal bonds not included in the Underlying Index, BFA will generally seek to obtain bonds that pay interest that is exempt from U.S. federal income taxes, the federal AMT and the federal Medicare tax. The interest on any money market instruments held by the Fund may be subject to the federal AMT or the federal Medicare tax.

Events occurring after the date of issuance of a municipal bond or after the Fund’s acquisition of a municipal bond may result in a determination that interest on that bond is includible in gross income for U.S. federal income tax, federal AMT or federal Medicare tax purposes retroactively to its date of issuance. Such a determination may cause a portion of prior distributions by the Fund to its shareholders to be taxable to

Tracking Error Risk. Imperfect correlation between the Fund’s portfolio securities and those in the Underlying Index, rounding of prices, changes to the Underlying Index and regulatory requirements may cause tracking error, which is the divergence of the Fund’s performance from that of the Underlying Index. 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. Because the Fund employs a representative sampling strategy, the Fund may experience tracking error to a greater extent than a fund that seeks to replicate an index.

A description of the Trust’s policies and procedures with respect to the disclosure of the Fund’s portfolio securities is available in the Fund’s statement of additional information (“SAI”). The top holdings of the Fund can be found at www.iShares.com. Fund fact sheets provide information regarding the Fund’s top holdings and may be requested by calling 1-800-iShares (1-800-474-2737).

Investment Adviser. As investment adviser, BFA has overall responsibility for the general management and administration of the Trust. BFA provides an investment program for the Fund and manages the investment of the Fund’s assets. In managing the Fund, BFA may draw upon the research and expertise of its asset management affiliates with respect to certain portfolio securities. In seeking to achieve the Fund’s investment objective, BFA uses teams of portfolio managers, investment strategists and other investment specialists. This team approach brings together many disciplines and leverages BFA’s extensive resources.

Pursuant to the Investment Advisory Agreement between BFA and the Trust (entered into on behalf of the Fund), BFA is responsible for substantially all expenses of the Fund, except interest expenses, taxes, brokerage expenses, future distribution fees or expenses and extraordinary expenses.

For its investment advisory services to the Fund, BFA is entitled to receive a management fee from the Fund based on a percentage of the Fund’s average daily net assets, at an annual rate of 0.30%.

A discussion regarding the basis for the Board’s approval of the Investment Advisory Agreement with BFA is available in the Fund’s annual report for the period ended March 31, 2010.

Portfolio Managers. James Mauro and Scott Radell are primarily responsible for the day-to-day management of the Fund. Each Portfolio Manager is responsible for various functions related to portfolio management, including, but not limited to, investing cash inflows, coordinating with members of his portfolio management team to focus on certain asset classes, implementing investment strategy, researching and reviewing investment strategy and overseeing members of his portfolio management team that have more limited responsibilities.

James Mauro has been employed by BFA (formerly, Barclays Global Fund Advisors (“BGFA”)) and BTC (formerly, Barclays Global Investors, N.A. (“BGI”)) as a portfolio manager since 2011. Prior to joining BTC, Mr. Mauro was a Vice President at State Street Global Advisors. Mr. Mauro has been a Portfolio Manager of the Fund since 2011.

Scott Radell has been employed by BFA and BTC as a portfolio manager since 2004. Mr. Radell was a credit strategist from 2003 to 2004 and became a portfolio manager at BGFA and BGI in 2004. Mr. Radell has been a Portfolio Manager of the Fund since 2010.

The Fund’s SAI provides additional information about the Portfolio Managers’ compensation, other accounts managed by the Portfolio Managers and the Portfolio Managers’ ownership (if any) of shares in the Fund.

Administrator, Custodian and Transfer Agent. State Street Bank and Trust Company (“State Street”) is the administrator, custodian and transfer agent for the Fund.

Conflicts of Interest. BFA wants you to know that there are certain entities with which BFA has relationships that may give rise to conflicts of interest, or the appearance of conflicts of interest. These entities include the following: BFA’s affiliates (including BlackRock and The PNC Financial Services Group, Inc., and each of their affiliates, directors, partners, trustees, managing members, officers and employees (collectively, the “Affiliates”)) and BlackRock’s significant shareholder Barclays Bank PLC and its affiliates, including Barclays PLC (each, an “Entity” and together the “Entities”).

BFA, one or more Affiliates or Entities may engage in proprietary trading and advise accounts and funds that have investment objectives similar to those of the Fund and/or that engage in and compete for transactions in the same types of securities, currencies and other instruments as the Fund, including in securities issued by other open-end and closed-end investment management companies, including investment companies that are affiliated with the Fund and BFA, to the extent permitted under the Investment Company Act of 1940, as amended (the “1940 Act”). The trading activities of BFA, these Affiliates and Entities are carried out without reference to positions held directly or indirectly by the Fund and may result in BFA, an Affiliate or an Entity having positions that are adverse to those of the Fund.

No Affiliate or Entity is under any obligation to share any investment opportunity, idea or strategy with the Fund. As a result, an Affiliate or an Entity may compete with the Fund for appropriate investment opportunities. As a result of this and several other factors, the results of the Fund’s investment activities may differ from those of an Affiliate or an Entity and of other accounts managed by an Affiliate or an Entity, and it is possible that the Fund could sustain losses during periods in which one or more Affiliates or Entities and other accounts achieve profits on their trading for proprietary or other accounts. The opposite result is also possible.

The Fund may, from time to time, enter into transactions in which BFA, an Affiliate’s or an Entity’s clients have an interest adverse to the Fund. Furthermore, transactions undertaken by Affiliate-advised clients may adversely impact the Fund. Transactions by one or more Affiliate- or Entity-advised clients or BFA may have the effect of diluting or otherwise disadvantaging the values, prices or investment strategies of the Fund.

An Entity may maintain securities indices as part of its product offerings. Index-based funds seek to track the performance of securities indices and may use the name of the index in the fund name. Index providers, including the Entities, may be paid licensing fees for use of their indices or index names. Entities will not be obligated to license their indices to BFA and its Affiliates, and BFA and its Affiliates will not be assured that the terms of any index licensing agreement with the Entities will be as favorable as those terms offered to other index licensees.

Pursuant to a securities lending program approved by the Board, the Fund has retained an Affiliate of BFA to serve as the securities lending agent for the Fund to the extent that the Fund participates in the securities lending program. For these services, the lending agent may receive a fee from the Fund, including a fee based on the returns earned on the Fund’s investment of the cash received as collateral for any loaned securities. In addition, one or more Affiliates may be among the entities to which the Fund may lend its portfolio securities under the securities lending program.

The activities of BFA, Affiliates or Entities may give rise to other conflicts of interest that could disadvantage the Fund and its shareholders. BFA has adopted policies and procedures designed to address these potential conflicts of interest. See the Fund’s SAI for further information.

Additional shareholder information, including how to buy and sell shares of the Fund, is available free of charge by calling toll-free: 1-800-iShares (1-800-474-2737) or visiting our website at www.iShares.com.

Buying and Selling Shares. Shares of the Fund are listed on a national securities exchange for trading during the trading day. Shares can be bought and sold throughout the trading day like shares of other publicly-traded companies. The Trust does not impose any minimum investment for shares of the Fund purchased on an exchange. Buying or selling Fund shares on an exchange involves two types of costs that may apply to all securities transactions. When buying or selling shares of the Fund through a broker, you will likely incur a brokerage commission or other charges determined by your broker. In addition, you may incur the cost of the “spread” – that is, any difference between the bid price and the ask price. The commission is frequently a fixed amount and may be a significant proportional cost for investors seeking to buy or sell small amounts of shares. The spread varies over time for shares of the Fund based on its trading volume and market liquidity, and is generally lower if the Fund has a lot of trading volume and market liquidity and higher if the Fund has little trading volume and market liquidity. The Fund’s shares trade under the trading symbol “MUAA.”

Shares of the Fund may be acquired or redeemed directly from the Fund only in Creation Units or multiples thereof, as discussed in the Creations and Redemptions section of this Prospectus. Only an Authorized Participant (as defined in the Creations and Redemptions section) may engage in creation or redemption transactions directly with the Fund. Once created, shares of the Fund generally trade in the secondary market in amounts less than a Creation Unit.

The Board has adopted a policy of not monitoring for frequent purchases and redemptions of Fund shares (“frequent trading”) that appear to attempt to take

The national securities exchange on which the Fund’s shares are listed is open for trading Monday through Friday and is closed on weekends and the following holidays: New Year’s Day, Martin Luther King, Jr. Day, Presidents’ Day, Good Friday, Memorial Day, Independence Day, Labor Day, Thanksgiving Day and Christmas Day. The Fund’s primary listing exchange is NYSE Arca.

Section 12(d)(1) of the 1940 Act restricts investments by investment companies in the securities of other investment companies. Registered investment companies are permitted to invest in the Fund beyond the limits set forth in Section 12(d)(1), subject to certain terms and conditions set forth in SEC rules or in an SEC exemptive order issued to the Trust. In order for a registered investment company to invest in shares of the Fund pursuant to the exemptive relief obtained by the Trust from the limitations of Section 12(d)(1), the registered investment company must enter into an agreement with the Trust.

Book Entry. Shares of the Fund are held in book-entry form, which means that no stock certificates are issued. The Depository Trust Company (“DTC”) or its nominee is the record owner of all outstanding shares of the Fund and is recognized as the owner of all shares for all purposes.

Investors owning shares of the Fund are beneficial owners as shown on the records of DTC or its participants. DTC serves as the securities depository for shares of the Fund. DTC participants include securities brokers and dealers, banks, trust companies, clearing corporations and other institutions that directly or indirectly maintain a custodial relationship with DTC. As a beneficial owner of shares, you are not entitled to receive physical delivery of stock certificates or to have shares registered in your name, and you are not considered a registered owner of shares. Therefore, to exercise any right as an owner of shares, you must rely upon the procedures of DTC and its participants. These procedures are the same as those that apply to any other securities that you hold in book-entry or “street name” form.

Determination of Net Asset Value. The NAV of the Fund is generally determined once daily Monday through Friday generally as of the regularly scheduled close of business of the New York Stock Exchange (“NYSE”) (normally 4:00 p.m., Eastern time) on each day that the NYSE is open for trading, based on prices at the time of closing, provided that (a) any assets or liabilities denominated in currencies other than the U.S. dollar are translated into U.S. dollars at the prevailing market rates, generally at the time the NAV is calculated, on the date of valuation as quoted by one or more major banks or dealers that makes a two-way market in such currencies (or a data service provider based on quotations received from such banks or dealers) and (b) U.S. fixed-income assets may be valued as of the announced closing time for trading in fixed-income instruments on any day that the Securities Industry and Financial Markets Association announces an early closing time. The NAV of the Fund is calculated by dividing the value of the net assets of the Fund (i.e., the value of its total assets less total liabilities) by the total number of outstanding shares of the Fund, generally rounded to the nearest cent.

The securities and other assets of the Fund are valued pursuant to the pricing policy and procedures approved by the Board. The Fund utilizes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three broad levels. Inputs may be based on independent market data (“observable inputs”) or they may be internally developed (“unobservable inputs”). The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy are as follows:

• Level 1 – Inputs that reflect unadjusted quoted prices in active markets for identical assets or liabilities that the Fund has the ability to access at the measurement date;

• Level 2 – Inputs other than quoted prices included within Level 1 that are observable for the asset or liability either directly or indirectly, including quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not considered to be active, inputs other than quoted prices that are observable for the asset or liability and inputs that are derived principally from or corroborated by observable market data by correlation or other means; and

The level of a value determined for a financial instrument within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement in its entirety. The categorization of a value determined for a financial instrument within the hierarchy is based upon the pricing transparency of the instrument and does not necessarily correspond to the Fund’s perceived risk of that instrument.

Valuing the Fund’s investments using fair value pricing will result in using prices for those investments that may differ from current market valuations. Use of fair value prices and certain current market valuations could result in a difference between the prices used to calculate the Fund’s NAV and the prices used by the Underlying Index, which, in turn, could result in a difference between the Fund’s performance and the performance of the Underlying Index.

General Policies. Dividends from net investment income, if any, generally are declared and paid monthly by the Fund. Distributions of net realized securities gains, if any, generally are declared and paid once a year, but the Trust may make distributions on a more frequent basis for the Fund. The Trust reserves the right to declare special distributions if, in its reasonable discretion, such action is necessary or advisable to preserve its status as a regulated investment company or to avoid imposition of income or excise taxes on undistributed income or realized gains.

Dividends and other distributions on shares of the Fund are distributed on a pro rata basis to beneficial owners of such shares. Dividend payments are made through DTC participants and indirect participants to beneficial owners then of record with proceeds received from the Fund.

Dividend Reinvestment Service. No dividend reinvestment service is provided by the Trust. Broker-dealers may make available the DTC book-entry Dividend Reinvestment Service for use by beneficial owners of the Fund for reinvestment of their dividend distributions. Beneficial owners should contact their broker to determine the availability and costs of the service and the details of participation therein. Brokers may require beneficial owners to adhere to specific procedures and timetables. If this service is available and used, dividend distributions of both income and realized gains will be automatically reinvested in additional whole shares of the Fund purchased in the secondary market.

Taxes. As with any investment, you should consider how your investment in shares of the Fund will be taxed. The tax information in this Prospectus is provided as general information. You should consult your own tax professional about the tax consequences of an investment in shares of the Fund.

Unless your investment in Fund shares is made through a tax-exempt entity or tax-deferred retirement account, such as an IRA, you need to be aware of the possible tax consequences when the Fund makes distributions or you sell Fund shares. In general, given its investment strategy, the Fund would not be an appropriate investment for a tax deferred retirement account such as an IRA.

Taxes on Distributions. Dividends paid by the Fund that are properly reported as tax-exempt interest dividends will not be subject to regular U.S. federal income tax. The Fund intends to invest its assets in a manner such that dividend distributions to its shareholders will generally be exempt from U.S. federal income taxation, including the federal AMT. Dividends paid by the Fund will be exempt from U.S. federal income tax (though not necessarily exempt from state and local taxation) to the extent of the Fund’s tax-exempt interest income as long as 50% or more of the value of the Fund’s assets at the end of each quarter is invested in state, municipal and other bonds that are excluded from gross income for U.S. federal income tax purposes and as long as the Fund properly reports such dividends as tax-exempt interest dividends. Exempt interest dividends from interest earned on municipal securities of a state, or its political subdivisions, may be exempt from income tax in that state. However, income from municipal securities of other states generally will not qualify for tax-free treatment.

Distributions from the Fund’s net investment income other than from net tax-exempt income, including distributions of income from securities lending and distributions out of the Fund’s net short-term capital gains, if any, are taxable to you as ordinary income. The Fund’s distributions of net long-term capital gains, if any, in excess of net short-term capital losses (capital gain dividends) are taxable to you as long-term capital gains, regardless of how long you have held the Fund’s shares. Distributions taxable as ordinary income or capital gains will be subject to a 3.8% U.S. federal Medicare contribution tax on “net investment income,” beginning in 2013 for individuals with incomes exceeding $200,000 ($250,000 if married and filing jointly). Distributions from the Fund are not expected to qualify as qualified dividend income. In general, any taxable distributions are subject to U.S. federal income tax for the year when they are paid. Certain distributions paid in January however, may be treated as paid on December 31 of the prior year.

Any market discount recognized on a bond is taxable as ordinary income. A market discount bond is a bond acquired in the secondary market at a price below redemption value or adjusted issue price if issued with original issue discount. Absent an election by the Fund to include the market discount in income as it accrues, gain on the Fund’s disposition of such an obligation will be treated as ordinary income rather than capital gain to the extent of the accrued market discount.

If you lend your Fund shares pursuant to securities lending arrangements, you may lose the ability to treat Fund dividends paid while the shares are held by the borrower as tax-exempt income. Consult your financial intermediary or tax advisor.

A 30% withholding tax will be imposed on dividends and redemption proceeds paid after December 31, 2012, to (i) foreign financial institutions including non-U.S. investment funds unless they agree to collect and disclose to the IRS information regarding their direct and indirect U.S. account holders and (ii) certain other foreign entities unless they certify certain information regarding their direct and indirect U.S. owners. To avoid withholding, foreign financial institutions will need to enter into agreements with the IRS which state that they will provide the IRS information including the name, address and taxpayer identification number of direct and indirect U.S. account holders, comply with due diligence procedures with respect to the identification of U.S. accounts, report to the IRS certain information with respect to U.S. accounts maintained, agree to withhold tax on certain payments made to non-compliant foreign financial institutions or to account holders who fail to provide the required information, and determine certain other information as to their account holders. Other foreign entities will need to provide the name, address, and taxpayer identification number of each substantial U.S. owner or certifications of no substantial U.S. ownership unless certain exceptions apply.

If you are a resident or a citizen of the United States, by law, back-up withholding (currently at a rate of 28%) will apply to your distributions and proceeds if you have not provided a taxpayer identification number or social security number and made other required certifications.

Shareholders will receive information after the end of each year setting forth the amount of dividends and long-term capital gains distributed to them by the Fund during the prior year. Likewise, the amount of tax-exempt income that the Fund distributes will be reported and such income must be reported on the shareholder’s U.S. federal income tax return.

Taxes When Shares are Sold. Currently, any capital gain or loss realized upon a sale of Fund shares is generally treated as a long-term gain or loss if the shares have been held for more than one year. Any capital gain or loss realized upon a sale of Fund shares held for one year or less is generally treated as short-term gain or loss, except that any capital loss on the sale of shares held for six months or less is treated as long-term capital loss to the extent that capital gain dividends were paid with respect to such shares. Beginning in 2013, any such capital gains, including from sales of Fund shares or from capital gain dividends, will be included in “net investment income” for purposes of the 3.8% U.S. federal Medicare contribution tax mentioned above.

The foregoing discussion summarizes some of the consequences under current U.S. federal tax law of an investment in the Fund. It is not a substitute for personal tax advice. You may also be subject to state and local taxation on Fund distributions and sales of shares. Consult your personal tax adviser about the potential tax consequences of an investment in shares of the Fund under all applicable tax laws.

Similarly, shares can be redeemed only in Creation Units, generally in-kind for a portfolio of bonds held by the Fund (“Fund Securities”) and a specified amount of cash. Except when aggregated in Creation Units, shares are not redeemable by the Fund. The prices at which creations and redemptions occur are based on the next calculation of NAV after an order is received in a form described in the authorized participant agreement.

The portfolio of securities required for purchase of a Creation Unit may be different than the portfolio of securities the Fund will deliver upon redemption of Fund shares. The Deposit Securities and Fund Securities, as the case may be, in connection with a purchase or redemption of a Creation Unit, will correspond pro rata, to the extent practicable, to the securities held by the Fund. As the planned termination date of the Fund approaches, the Fund may elect to accept create orders mostly or entirely in cash. As bonds held by the fund begin to mature, both creations and redemptions will be effected increasingly in cash.

The Fund intends to comply with the U.S. federal securities laws in accepting securities for deposit and satisfying redemptions with redemption securities by, among other means, assuring that any securities accepted for deposit and any securities used to satisfy redemption requests will be sold in transactions that would be exempt from registration under the Securities Act of 1933, as amended (the “1933 Act”). Further, an Authorized Participant that is not a “qualified institutional buyer,” as such term is defined under Rule 144A of the 1933 Act, will not be able to receive Fund Securities that are restricted securities eligible for resale under Rule 144A.

Creations and redemptions must be made through a firm that is either a member of the Continuous Net Settlement System of the National Securities Clearing Corporation or a DTC participant and has executed an agreement with the Distributor with respect to creations and redemptions of Creation Unit aggregations. Information about the procedures regarding creation and redemption of Creation Units (including the cut-off times for receipt of creation and redemption orders) is included in the Fund’s SAI.

Because new shares may be created and issued on an ongoing basis, at any point during the life of the Fund a “distribution,” as such term is used in the 1933 Act, may be occurring. Broker-dealers and other persons are cautioned that some activities on their part may, depending on the circumstances, result in their being deemed participants in a distribution in a manner that could render them statutory underwriters and subject to the prospectus delivery and liability provisions of the 1933 Act. Any determination of whether one is an underwriter must take into account all the relevant facts and circumstances of each particular case.

Broker-dealers should also note that dealers who are not “underwriters” but are participating in a distribution (as contrasted to ordinary secondary transactions), and

The following table shows, as of May 31, 2011, the approximate value of one Creation Unit, standard fees and maximum additional charges for creations and redemptions (as described above):

Householding. Householding is an option available to certain Fund investors. Householding is a method of delivery, based on the preference of the individual investor, in which a single copy of certain shareholder documents can be delivered to investors who share the same address, even if their accounts are registered under different names. Please contact your broker-dealer if you are interested in enrolling in householding and receiving a single copy of prospectuses and other shareholder documents, or if you are currently enrolled in householding and wish to change your householding status.

The Distributor distributes Creation Units for the Fund on an agency basis. The Distributor does not maintain a secondary market in shares of the Fund. The Distributor has no role in determining the policies of the Fund or the securities that are purchased or sold by the Fund. The Distributor’s principal address is One Freedom Valley Drive, Oaks, PA 19456.

In addition, BFA or its Affiliates make payments to broker-dealers, banks or other financial intermediaries (together, “intermediaries”) related to marketing activities and presentations, educational training programs, conferences, the development of technology platforms and reporting systems, or their making shares of the Fund and certain other iShares funds available to their customers. Such payments, which may be significant to the intermediary, are not made by the Fund. Rather, such payments are made by BFA or its Affiliates from their own resources, which come directly or indirectly in part from fees paid by the iShares funds complex. Payments of this type are sometimes referred to as revenue-sharing payments. A financial intermediary may make decisions about which investment options it recommends or makes available, or the level of services provided, to its customers based on the revenue-sharing payments it is eligible to receive. Therefore, such payments to an intermediary create conflicts of interest between the intermediary and its customers and may cause the intermediary to recommend the Fund or other iShares funds over another investment. More information regarding these payments is contained in the Fund’s SAI. Please contact your salesperson or other investment professional for more information regarding any such payments his or her firm may receive from BFA or its Affiliates.

The financial highlights table is intended to help investors understand the Fund’s financial performance since inception. Certain information reflects financial results for a single share of the Fund. The total returns in the table represents the rate that an investor would have earned (or lost) on an investment in the Fund, assuming reinvestment of all dividends and distributions. This information has been audited by PricewaterhouseCoopers LLP, whose report is included, along with the Fund’s financial statements, in the Fund’s Annual Report (available upon request).

S&P is the Index Provider for the Underlying Index. S&P is not affiliated with the Trust, BTC, BFA, State Street, the Distributor or any of their respective affiliates.

S&P provides financial, economic and investment information and analytical services to the financial community. S&P calculates and maintains the S&P Global 1200 Index^TM, which includes the S&P 500^®for the United States, the S&P Europe 350 Index^TM for Continental Europe and the United Kingdom, the S&P/TOPIX 150 Index^TM for Japan, the S&P Asia 50 Index^TM, the S&P/TSX 60 Index^TM for Canada, the S&P/ASX 50 Index^TM, and the S&P Latin America 40 Index^TM. S&P also publishes the S&P MidCap 400 Index^TM, S&P SmallCap 600^® Index, S&P Composite 1500^® and S&P REIT Composite Index^TM for the United States. S&P calculates and maintains the S&P Global BMI Equity Index^TM Series, a set of comprehensive rules-based benchmarks covering developed and emerging countries around the world. Company additions to and deletions from a S&P equity index do not in any way reflect an opinion on the investment merits of the company.

BTC has entered into a license agreement with the Index Provider to use the Underlying Index. BTC sublicenses rights in the Underlying Index to the Trust at no charge.

The Fund is not sponsored, endorsed, sold or promoted by S&P or its affiliates. S&P and its affiliates make no representation or warranty, express or implied, to the owners of shares of the Fund or any member of the public regarding the advisability of investing in securities generally or in the Fund particularly or the ability of the Underlying Index to track general stock market performance. S&P and its affiliates’ only relationship to the Trust, BTC and BFA is the licensing of certain trademarks and trade names of S&P and its affiliates and of the Underlying Index which is determined, composed and calculated by S&P and its affiliates without regard to the Trust, BTC, BFA or the Fund. S&P and its affiliates have no obligation to take the needs of BTC, BFA or the owners of shares of the Fund into consideration in determining, composing or calculating the Underlying Index. S&P and its affiliates are not responsible for and have not participated in the determination of the prices and amount of shares of the Fund, or the timing of the issuance or sale of such shares or in the determination or calculation of the equation by which shares of the Fund are to be converted into cash. S&P and its affiliates have no obligation or liability in connection with the administration, marketing or trading of shares of the Fund. S&P and its affiliates do not guarantee the accuracy or the completeness of the Underlying Index or any data included therein and S&P and its affiliates shall have no liability for any errors, omissions, or interruptions therein.

S&P and its affiliates make no warranty, express or implied, as to results to be obtained by BTC, BFA, owners of shares of the Fund or any other person or entity from the use of the Underlying Index or any data included therein. S&P and its affiliates make no express or implied warranties and expressly disclaim

Shares of the Fund are not sponsored, endorsed or promoted by NYSE Arca. NYSE Arca makes no representation or warranty, express or implied, to the owners of the shares of the Fund or any member of the public regarding the ability of the Fund to track the total return performance of the Underlying Index or the ability of the Underlying Index to track stock market performance. NYSE Arca is not responsible for, nor has it participated in, the determination of the compilation or the calculation of the Underlying Index, nor in the determination of the timing of, prices of, or quantities of shares of the Fund to be issued, nor in the determination or calculation of the equation by which the shares are redeemable. NYSE Arca has no obligation or liability to owners of the shares of the Fund in connection with the administration, marketing or trading of the shares of the Fund.

NYSE Arca does not guarantee the accuracy and/or the completeness of the Underlying Index or any data included therein. NYSE Arca makes no warranty, express or implied, as to results to be obtained by the Trust on behalf of the Fund as licensee, licensee’s customers and counterparties, owners of the shares of the Fund, or any other person or entity from the use of the subject index or any data included therein in connection with the rights licensed as described herein or for any other use. NYSE Arca makes no express or implied warranties and hereby expressly disclaims all warranties of merchantability or fitness for a particular purpose with respect to the Underlying Index or any data included therein. Without limiting any of the foregoing, in no event shall NYSE Arca have any liability for any direct, indirect, special, punitive, consequential or any other damages (including lost profits) even if notified of the possibility of such damages.

BFA does not guarantee the accuracy or the completeness of the Underlying Index or any data included therein and BFA shall have no liability for any errors, omissions or interruptions therein.

BFA makes no warranty, express or implied, to the owners of shares of the Fund or to any other person or entity, as to results to be obtained by the Fund from the use of the Underlying Index or any data included therein. BFA makes no express or implied warranties and expressly disclaims all warranties of merchantability or fitness for a particular purpose or use with respect to the Underlying Index or any data included therein. Without limiting any of the foregoing, in no event shall BFA have any liability for any special, punitive, direct, indirect or consequential damages (including lost profits), even if notified of the possibility of such damages.

The table that follows presents information about the differences between the daily market price on secondary markets for shares of the Fund and the Fund’s NAV. NAV is the price at which the Fund issues and redeems shares. It is calculated in accordance with the standard formula for valuing mutual fund shares. The price used to calculate market returns (“Market Price”) of the Fund generally is determined using the midpoint between the highest bid and the lowest offer on the primary securities exchange on which shares of the Fund are listed for trading, as of the time that the Fund’s NAV is calculated. The Fund’s Market Price may be at, above or below its NAV. The NAV of the Fund will fluctuate with changes in the value of its portfolio holdings. The Market Price of the Fund will fluctuate in accordance with changes in its NAV, as well as market supply and demand.

Premiums or discounts are the differences (expressed as a percentage) between the NAV and Market Price of the Fund on a given day, generally at the time the NAV is calculated. A premium is the amount that the Fund is trading above the reported NAV, expressed as a percentage of the NAV. A discount is the amount that the Fund is trading below the reported NAV, expressed as a percentage of the NAV.

The following information shows the frequency of distributions of premiums and discounts for the Fund from April 1, 2010, through June 30, 2011.

Each line in the table shows the number of trading days in which the Fund traded within the premium/discount range indicated. The number of trading days in each premium/discount range is also shown as a percentage of the total number of trading days in the period covered by the table. All data presented here represents past performance, which cannot be used to predict future results.

Premium/Discount Range	Number of Days	Percentage of Total Days
Greater than 1.0% and Less than 1.5%	4	1.27%
Greater than 0.5% and Less than 1.0%	96	30.38
Between 0.5% and -0.5%	216	68.35
	316	100.00%

The table that follows presents information about the total returns of the Fund and the Underlying Index as of the fiscal year ended March 31, 2011.

“Average Annual Total Returns” represent the average annual change in value of an investment over the periods indicated. “Cumulative Total Returns” represent the total change in value of an investment over the period indicated.

The Fund’s NAV is the value of one share of the Fund as calculated in accordance with the standard formula for valuing mutual fund shares. The NAV return is based on the NAV of the Fund and the market return is based on the Market Price of the Fund. Market Price is determined by using the midpoint between the highest bid and the lowest offer on the primary stock exchange on which shares of the Fund are listed for trading, as of the time that the Fund’s NAV is calculated. Since shares of the Fund did not trade in the secondary market until after the Fund’s inception, for the period from inception to the first day of secondary market trading in shares of the Fund, the NAV of the Fund is used as a proxy for the Market Price to calculate market returns. Market and NAV returns assume that dividends and capital gain distributions have been reinvested in the Fund at Market Price and NAV, respectively.

An index is a statistical composite that tracks a specified financial market or sector. Unlike the Fund, the Underlying Index does not actually hold a portfolio of securities and therefore does not incur the expenses incurred by the Fund. These expenses negatively impact the performance of the Fund. Also, market returns do not include brokerage commissions that may be payable on secondary market transactions. If brokerage commissions were included, market returns would be lower. The returns shown in the following tables do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or the redemption or sale of Fund shares. The investment return and principal value of shares of the Fund will vary with changes in market conditions. Shares of the Fund may be worth more or less than their original cost when they are redeemed or sold in the market. The Fund’s past performance is no guarantee of future results.

Copies of the Prospectus, SAI and recent shareholder reports can be found on our website at www.iShares.com. For more information about the Fund, you may request a copy of the SAI. The SAI provides detailed information about the Fund and is incorporated by reference into this Prospectus. This means that the SAI, for legal purposes, is a part of this Prospectus.

Additional information about the Fund’s investments is available in the Fund’s Annual and Semi-Annual reports to shareholders. In the Fund’s Annual Report, you will find a discussion of the market conditions and investment strategies that significantly affected the Fund’s performance during the last fiscal year.

If you have any questions about the Trust or shares of the Fund or you wish to obtain the SAI, Semi-Annual or Annual report free of charge, please:

Information about the Fund (including the SAI) can be reviewed and copied at the SEC’s Public Reference Room in Washington, D.C., and information on the operation of the Public Reference Room may be obtained by calling the SEC at 1-202-551-8090. Reports and other information about the Fund are available on the EDGAR database on the SEC’s website at www.sec.gov, and copies of this information may be obtained, after paying a duplicating fee, by electronic request at the following e-mail address: publicinfo@sec.gov, or by writing to the SEC’s Public Reference Section, Washington, D.C. 20549-1520.

No person is authorized to give any information or to make any representations about the Fund and its shares not contained in this Prospectus and you should not rely on any other information. Read and keep the Prospectus for future reference.


Fund Overview	S-1
More Information About the Fund	1
A Further Discussion of Principal Risks	2
Portfolio Holdings Information	7
Management	7
Shareholder Information	10
Distribution	18
Financial Highlights	19
Index Provider	20
Disclaimers	20
Supplemental Information	22

“Standard & Poor’s^®,” “S&P^®” and “S&P AMT-Free Municipal Series 2013 Index^TM” are trademarks of Standard & Poor’s Financial Services LLC (a subsidiary of The McGraw-Hill Companies) licensed for use for certain purposes by BlackRock Institutional Trust Company, N.A. (“BTC”). iShares^® is a registered trademark of BTC.

The iShares 2013 S&P AMT-Free Municipal Series (the “Fund”) seeks investment results that correspond generally to the price and yield performance, before fees and expenses, of the S&P AMT-Free Municipal Series 2013 Index^TM (the “Underlying Index”). The Fund does not seek to return any predetermined amount at maturity.

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

The Underlying Index measures the performance of investment-grade U.S. municipal bonds maturing in 2013. As of May 31, 2011, there were 3,194 issues in the Underlying Index.

The Underlying Index includes municipal bonds primarily from issuers that are state or local governments or agencies (including the Commonwealth of Puerto Rico and U.S. territories such as the U.S. Virgin Islands and Guam) such that the interest on the bonds is exempt from U.S. federal income taxes and the federal alternative minimum tax (“AMT”). Each bond must have a rating of at least BBB- by Standard & Poor’s Financial Services LLC (a subsidiary of The McGraw-Hill Companies) (“S&P”), Baa3 by Moody’s Investors Service, Inc. (“Moody’s”), or BBB- by Fitch, Inc. and must have a minimum maturity par amount of $2 million to be eligible for inclusion in the Underlying Index. 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 between June 1 and August 31 of the year referenced in the name of the Underlying Index. When a bond matures in the Underlying Index, an amount representing its value at maturity 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 performance of the S&P’s Weekly High Grade Index, which consists of Moody’s Investment Grade-1 municipal tax-exempt notes that are not subject to AMT. By August 31, 2013, the Underlying Index is expected to consist entirely of cash carried in this manner. The Underlying Index is a market value weighted index and is rebalanced after the close on the last business day of each month.

The Fund generally invests at least 80% of its assets in the securities of its Underlying Index, except during the last months of the Fund’s operations, as described below. The Fund may at times invest up to 20% of its assets in cash and cash equivalents (including money market funds affiliated with BFA), as well as in municipal bonds not included in the Underlying Index, but which BFA believes will help the Fund track its Underlying Index. For example, the Fund may invest in municipal bonds not included in the Underlying Index in order to reflect prospective changes in the Underlying Index (such as index reconstitutions, additions and deletions). 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, effective beginning in 2013, a federal Medicare contribution tax of 3.8% on “net investment income,” including dividends, interest and capital gains. In addition, the Fund may invest any cash assets in one or more affiliated municipal money market funds. 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 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. On or about August 31, 2013, the Fund will wind up and terminate, and its net assets will be distributed to then-current shareholders.

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

Asset Class Risk. Securities in the Underlying Index or in the Fund’s portfolio may underperform in comparison to the general securities markets or other asset classes.

Credit Risk. The Fund is subject to the risk that debt issuers and other counterparties may not honor their obligations.

Interest Rate Risk. An increase in interest rates may cause the value of fixed-income securities held by the Fund to decline.

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

As of the date of the Fund’s prospectus (the “Prospectus”), the Fund has been in operation for less than one full calendar year and therefore does not report its performance information.

ETFs are funds that trade like other publicly-traded securities. The Fund is designed to track an index. Similar to shares of an index mutual fund, each share of the Fund represents a partial ownership in an underlying portfolio of securities intended to track a market index. Unlike shares of a mutual fund, which can be bought and redeemed from the issuing fund by all shareholders at a price based on NAV, shares of the Fund may be purchased or redeemed directly from the Fund at NAV solely by authorized participants. Also unlike shares of a mutual fund, shares of the Fund are listed on a national securities exchange and trade in the secondary market at market prices that change throughout the day.

The Fund will wind up and terminate on or about August 31, 2013. Upon its termination, the Fund will distribute substantially all of its net assets, after making appropriate provision for any liabilities of the Fund, to then-current shareholders pursuant to a plan of liquidation. In the final months of the Fund’s operation, as the bonds it holds mature, its portfolio will transition to cash and cash-like instruments, including without limitation AMT-free tax-exempt municipal notes, variable rate demand notes and obligations, tender option bonds and municipal commercial paper. In accordance with the Trust’s Amended and Restated Declaration of Trust dated September 17, 2009, the Fund will terminate on the date above as approved by a majority of the Trust’s Board of Trustees (the “Board”) without requiring additional approval by Fund shareholders. The Board may extend the termination date if a majority of the Board determines the extension to be in the best interest of the Fund.