BLACKROCK FUNDS^SM

iShares MSCI Asia ex Japan Index Fund

BLACKROCK FUNDS III

iShares MSCI Total International Index Fund

(each, a “Fund” and collectively, the “Funds”)

Supplement dated July 28, 2017 to the Statement of Additional Information of each Fund

Effective immediately, each Fund may invest in eligible China A-shares listed and traded on the Shanghai Stock Exchange or the Shenzhen Stock Exchange through both the Shanghai-Hong Kong Stock Connect program and the Shenzhen-Hong Kong Stock Connect program, as applicable. Accordingly, effective immediately, the following change is made to the Part II of each Fund’s Statement of Additional Information.

The sections entitled “Investment Risks and Consideration — Risks of Investing in China — Risk of Investing through Stock Connect” and “Investment Risks and Consideration — Risks of Investing in China — A-Share Market Suspension Risk” are hereby deleted in their entirety and replaced with the following.

Risk of Investing through Stock Connect. China A-shares are equity securities of companies based in mainland China that trade on Chinese stock exchanges such as the Shanghai Stock Exchange (“SSE”) and the Shenzhen Stock Exchange (“SZSE”) (“A-shares”). Foreign investment in A-shares on the SSE and SZSE is historically not permitted, other than through a license granted under regulations in the PRC known as the Qualified Foreign Institutional Investor and Renminbi Qualified Foreign Institutional Investor systems. Each license permits investment in A-shares only up to a specified quota.

Investment in eligible A-shares listed and traded on the SSE or SZSE is also permitted through the Shanghai-Hong Kong Stock Connect program or the Shenzhen-Hong Kong Stock Connect program, as applicable (each, a “Stock Connect” and collectively, the “Stock Connects”). Each Stock Connect is a securities trading and clearing program established by Hong Kong Securities Clearing Company Limited (“HKSCC”), the SSE or SZSE, as applicable, and China Securities Depository and Clearing Corporation Limited (“CSDCC”) that aims to provide mutual stock market access between the PRC and Hong Kong by permitting investors to trade and settle shares on each market through their local exchanges. Certain Funds may invest in A-shares through Stock Connects or on such other stock exchanges in China which participate in Stock Connects from time to time. Under Stock Connects, a Fund’s trading of eligible A-shares listed on the SSE or SZSE, as applicable, would be effectuated through its Hong Kong broker.

Although no individual investment quotas or licensing requirements apply to investors in Stock Connects, trading through a Stock Connect’s Northbound Trading Link is subject to daily investment quota limitations that require that buy orders for A-shares be rejected once the daily quota is exceeded (although a Fund will be permitted to sell A-shares regardless of the quota). These limitations may restrict a Fund from investing in A-shares on a timely basis, which could affect the Fund’s ability to effectively pursue its investment strategy. Investment quotas are also subject to change. Investment in eligible A-shares through a Stock Connect is subject to trading, clearance and settlement procedures that could pose risks to a Fund. A-shares purchased through Stock Connects generally may not be sold or otherwise transferred other than through Stock Connects in accordance with applicable rules. For example, PRC regulations require that in order for an investor to sell any A-share on a certain trading day, there must be sufficient A-shares in the investor’s account before the market opens on that day. If there are insufficient A-shares in the investor’s account, the sell order will be rejected by the SSE or SZSE, as applicable. The Stock Exchange of Hong Kong (“SEHK”) carries out pre-trade checking on sell orders of certain stocks listed on the SSE market (“SSE Securities”) or SZSE market (“SZSE Securities”) of its participants (i.e., stock brokers) to ensure that this requirement is satisfied. While shares must be designated as eligible to be traded under a Stock Connect, those shares may also lose such designation, and if this occurs, such shares may be sold but cannot be purchased through a Stock Connect. In addition, Stock Connects will only

operate on days when both the Chinese and Hong Kong markets are open for trading and when banks in both markets are open on the corresponding settlement days. Therefore, an investment in A-shares through a Stock Connect may subject a Fund to a risk of price fluctuations on days where the Chinese market is open, but a Stock Connect is not trading. Moreover, day (turnaround) trading is not permitted on the A-shares market. If an investor buys A-shares on day “T,” the investor will only be able to sell the A-shares on or after day T+1. Further, since all trades of eligible Stock Connect A-shares must be settled in RMB, investors must have timely access to a reliable supply of offshore RMB, which cannot be guaranteed.

A-shares held through the nominee structure under a Stock Connect will be held through HKSCC as nominee on behalf of investors. The precise nature and rights of a Fund as the beneficial owner of the SSE Securities or SZSE Securities through HKSCC as nominee is not well defined under PRC law. There is lack of a clear definition of, and distinction between, legal ownership and beneficial ownership under PRC law and there have been few cases involving a nominee account structure in the PRC courts. The exact nature and methods of enforcement of the rights and interests of a Fund under PRC law is also uncertain. In the unlikely event that HKSCC becomes subject to winding up proceedings in Hong Kong there is a risk that the SSE Securities or SZSE Securities may not be regarded as held for the beneficial ownership of a Fund or as part of the general assets of HKSCC available for general distribution to its creditors. Notwithstanding the fact that HKSCC does not claim proprietary interests in the SSE Securities or SZSE Securities held in its omnibus stock account in the CSDCC, the CSDCC as the share registrar for SSE- or SZSE-listed companies will still treat HKSCC as one of the shareholders when it handles corporate actions in respect of such SSE Securities or SZSE Securities. HKSCC monitors the corporate actions affecting SSE Securities and SZSE Securities and keeps participants of Central Clearing and Settlement System (“CCASS”) informed of all such corporate actions that require CCASS participants to take steps in order to participate in them. Investors may only exercise their voting rights by providing their voting instructions to the HKSCC through participants of the CCASS. All voting instructions from CCASS participants will be consolidated by HKSCC, who will then submit a combined single voting instruction to the relevant SSE- or SZSE-listed company.

A Fund’s investments through a Stock Connect’s Northbound Trading Link are not covered by Hong Kong’s Investor Compensation Fund. Hong Kong’s Investor Compensation Fund is established to pay compensation to investors of any nationality who suffer pecuniary losses as a result of default of a licensed intermediary or authorized financial institution in relation to exchange-traded products in Hong Kong. In addition, since a Fund is carrying out Northbound trading through securities brokers in Hong Kong but not PRC brokers, it is not protected by the China Securities Investor Protection Fund in the PRC.

Market participants are able to participate in Stock Connects subject to meeting certain information technology capability, risk management and other requirements as may be specified by the relevant exchange and/or clearing house. Further, the “connectivity” in Stock Connects requires the routing of orders across the border of Hong Kong and the PRC. This requires the development of new information technology systems on the part of the SEHK and exchange participants. There is no assurance that these systems will function properly or will continue to be adapted to changes and developments in both markets. In the event that the relevant systems fail to function properly, trading in A-shares through Stock Connects could be disrupted.

The Shanghai-Hong Kong Stock Connect program launched in November 2014 and the Shenzhen-Hong Kong Stock Connect program launched in December 2016 and are both in their initial stages. The current regulations are untested and there is no certainty as to how they will be applied or interpreted going forward. In addition, the current regulations are subject to change and there can be no assurance that a Stock Connect will not be discontinued. New regulations may be issued from time to time by the regulators and stock exchanges in China and Hong Kong in connection with operations, legal enforcement and cross-border trades under Stock Connects. A Fund may be adversely affected as a result of such changes. Furthermore, the securities regimes and legal systems of China and Hong Kong differ significantly and issues may arise based on these differences. In the event that the relevant systems fail to function properly, trading in both markets through Stock Connects could be disrupted and a Fund’s ability to achieve its investment objective may be adversely affected. In addition, a Fund’s investments in A-shares through Stock Connects are generally subject to Chinese securities regulations and listing rules, among other restrictions. Further, different fees, costs and taxes are imposed on foreign

investors acquiring A-shares obtained through Stock Connects, and these fees, costs and taxes may be higher than comparable fees, costs and taxes imposed on owners of other securities providing similar investment exposure.

A-Share Market Suspension Risk. A-shares may only be bought from, or sold to, a Fund at times when the relevant A-shares may be sold or purchased on the relevant Chinese stock exchange. The A-shares market has a higher propensity for trading suspensions than many other global equity markets. Trading suspensions in certain stocks could lead to greater market execution risk and costs for a Fund. The SSE and SZSE currently apply a daily price limit, generally set at 10%, of the amount of fluctuation permitted in the prices of A-shares during a single trading day. The daily price limit refers to price movements only and does not restrict trading within the relevant limit. There can be no assurance that a liquid market on an exchange will exist for any particular A-share or for any particular time.

Shareholders should retain this Supplement for future reference.

SAI-STOCKCON-0717SUP