Supplement dated December 1, 2022 (the “Supplement”)

to the Summary Prospectus, Prospectus and

the Statement of Additional Information (the “SAI”) dated December 1 2022 for the iShares MSCI ACWI Low Carbon Target ETF (CRBN) (the “Fund”)

The first, second and third paragraphs of the section of the Summary Prospectus and Prospectus entitled “Principal Investment Strategies” are deleted in their entirety and replaced with the following:

The Fund seeks to track the investment results of the MSCI ACWI Low Carbon Target Index (the “Underlying Index”), which has been developed by MSCI Inc. (the “Index Provider” or “MSCI”). The Underlying Index is designed to address two dimensions of carbon exposure – carbon emissions and potential carbon emissions from fossil fuel reserves. By overweighting companies with low carbon emissions relative to enterprise value including cash (EVIC) and those with low potential carbon emissions from fossil fuel reserves relative to market capitalization, the Underlying Index aims to reflect a lower carbon exposure than that of the broad market. Carbon emissions and potential carbon emissions from fossil fuel reserves are measured based on an issuer’s reported data from annual reports, corporate social responsibility reports, the Carbon Disclosure Project, oil and gas industry bodies, and other relevant third-party sources. If an issuer does not report carbon emissions or potential carbon emissions from fossil fuel reserves, the data are estimated by MSCI using a proprietary model.

The Underlying Index is designed to achieve a target level of tracking relative to the MSCI ACWI Index (the “Parent Index”) while minimizing carbon exposure. The Underlying Index is a subset of the Parent Index

that measures the combined equity market performance of developed and emerging market countries. The Parent Index serves as the universe of eligible securities for the Underlying Index. The Index Provider begins with the Parent Index and excludes securities of companies involved with controversial weapons, companies involved in very severe ESG controversies and companies involved in the business of thermal coal mining and extraction of oil sands, based on percentage of revenue thresholds for certain categories (e.g. 1% or 5%) and categorical exclusions for others (e.g. controversial weapons) (in each case as determined by the Index Provider). Remaining securities included in the Parent Index are assigned a “carbon exposure” measured in terms of the issuer’s greenhouse gas emissions (relative to the issuer’s EVIC) and potential carbon emissions from fossil fuel reserves held by the issuer (per dollar of such issuer’s market capitalization, as measured during the semi-annual index review). Greenhouse gas emissions of the issuer includes direct greenhouse gas emissions by the issuer, indirect greenhouse gas emissions associated with the issuer’s purchase of energy, and indirect emissions occurring in the value chain of the issuer (in each case, as determined by the Index Provider). The Underlying Index is then constructed using a process that aims to achieve replicability and investability, subject to the following objective and constraints: (i) minimize carbon exposure subject to a tracking error constraint of 50 basis points relative to the Parent Index; (ii) the maximum weight of an Underlying Index constituent may not be greater than 20 times its weight in the Parent Index; (iii) country weights in the Underlying Index may not deviate more than 2% from the country weights in the Parent Index; and (iv) sector weights in the Underlying Index may not deviate more than 2% from the sector weights in the Parent Index, with the exception of the energy sector, where there is no weight constraint applied. The Underlying Index may still include significant exposure to large companies that have proportionately greater carbon exposure relative to smaller companies with lower carbon exposure due to the Underlying Index’s constraints on deviating from the market capitalization of Parent Index constituents.

The Underlying Index includes large- and mid‑capitalization companies and may change over time. As of December 1, 2022, a significant portion of the Underlying Index is represented by securities of companies in the financials and technology industries or sectors. The components of the Underlying Index are likely to change over time. As of December 1, 2022, the Underlying Index consisted of securities from the following countries or regions: Australia, Austria, Belgium, Brazil, Canada, Chile, China, Colombia, Czech Republic, Denmark, Egypt,

Finland, France, Germany, Greece, Hong Kong, India, Indonesia, Ireland, Israel, Italy, Japan, Kuwait, Malaysia, Mexico, the Netherlands, Norway, Peru, the Philippines, Poland, Portugal, Qatar, Saudi Arabia, Singapore, South Africa, South Korea, Spain, Sweden, Switzerland, Taiwan, Thailand, Turkey, the United Arab Emirates, the United Kingdom (the “U.K.”) and the U.S. (together, the “ACWI countries”). The lower carbon exposure sought by the Underlying Index may have no impact on (or no correlation with) the investment performance of the Fund.

If you have any questions, please call 1‑800‑iShares (1‑800‑474‑2737).

iShares^® is a registered trademark of BlackRock Fund Advisors and its affiliates.