iShares National Muni Bond ETF (MUB) Exchange: NYSE ARCA

The Fund seeks to track the investment results of the S&P National AMT-Free Municipal Bond IndexTM (the “Underlying Index”), which measures the performance of the investment-grade segment (as determined by S& P Dow Jones Indices LLC (the “Index Provider” or “SPDJI”)) of the U.S. municipal bond market. As of February 29, 2020, there were 12,234 issues in the Underlying Index. As of February February 29, 2020, a significant portion of the Underlying Index is represented by municipal bonds. The components of the Underlying Index are likely to change over time.The Underlying Index primarily includes municipal bonds from issuers that are state or local governments or agencies such that the interest on each such bond is exempt from U.S. federal income taxes. Each bond in the Underlying Index must have a rating of at least BBB- by Standard & Poor's® Global Ratings, a subsidiary of S&P Global, Baa3 by Moody’s Investors Service, Inc., or BBB- by Fitch Ratings, Inc. A bond must be rated by at least one of these three rating agencies in order to qualify for the Underlying Index, and the lowest rating will be used in determining if the bond is investment-grade. Each bond in the Underlying Index must be denominated in U.S. dollars, must be a constituent of an offering where the original offering amount was at least $100 million, and must have a minimum par amount of $25 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 $25 million as of the next rebalancing date. In addition, each bond must have a minimum term to maturity and/or pre-refunded or call date greater than or equal to one calendar month plus one calendar day to be included in the Underlying Index. The Underlying Index is a market-value weighted index, and the securities in the Underlying Index are updated 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 aiming to keep portfolio turnover low in comparison to actively managed investment companies.BFA uses a representative sampling indexing strategy to manage the Fund. “Representative sampling” is an indexing strategy that involves investing in a representative sample of securities that collectively has an investment profile similar to that of an applicable underlying index. The securities selected are expected to have, in the aggregate, investment characteristics (based on factors such as market value and industry weightings), fundamental characteristics (such as return variability, duration, maturity, credit ratings and yield) and liquidity measures similar to those of an applicable underlying index. The Fund may or may not hold all of the securities in the Underlying Index.The Fund generally will invest at least 90% of its assets in the component securities of the Underlying Index 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.” In addition, the Fund intends to invest any cash assets in one or more affiliated municipal money market funds, which may be advised by BFA or its affiliates. The Fund seeks to track the investment results of the Underlying Index before fees and expenses of the Fund.The Fund may invest in shares of other iShares funds that provide substantially similar exposure to the securities in the Underlying Index. BFA will waive a portion of its management fees in an amount equal to the acquired fund fees and expenses, if any, attributable to the Fund's investment in other iShares funds.The Underlying Index is a product of 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 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.