Strategy. The Fund is a fund-of-funds that aims to provide diversification across traditional fixed-income (debt) asset classesU.S. and foreign corporate bonds, U.S. government bonds, sovereign bonds issued by foreign governments, mortgage-backed securities and asset-backed securitiesby investing in a portfolio of unaffiliated exchange-traded funds (ETFs) sponsored by BlackRock Fund Advisors (or its affiliates) (BFA) and which utilize a passive index-based strategy to track the performance of fixed-income indexes (each, an Underlying Fund or collectively, Underlying Funds). Some indexes are designed to provide broader market exposure, while other indexes are designed to provide exposure to specific market sectors. Each Underlying Fund invests directly in bonds and other debt securities, as appropriate to its investment objective and strategies. The Fund invests, under normal circumstances, … Show more… The Fund is a fund-of-funds that aims to provide diversification across traditional fixed-income (debt) asset classesU.S. and foreign corporate bonds, U.S. government bonds, sovereign bonds issued by foreign governments, mortgage-backed securities and asset-backed securitiesby investing in a portfolio of unaffiliated exchange-traded funds (ETFs) sponsored by BlackRock Fund Advisors (or its affiliates) (BFA) and which utilize a passive index-based strategy to track the performance of fixed-income indexes (each, an Underlying Fund or collectively, Underlying Funds). Some indexes are designed to provide broader market exposure, while other indexes are designed to provide exposure to specific market sectors. Each Underlying Fund invests directly in bonds and other debt securities, as appropriate to its investment objective and strategies. The Fund invests, under normal circumstances, at least 80% of its net assets in fixed-income securities through its investments in ETFs. The Fund may enter into repurchase agreements to generate additional income. Securities in which the Underlying Funds invest may include those of any maturity or duration, and those that are either investment grade or below investment grade. Securities that are rated below investment grade often are known as junk bonds or high-yield bonds, and are considered to be speculative. Many foreign bonds are denominated in currencies other than the U.S. dollar. BFA uses a passive or indexing approach to try to achieve each Underlying Funds investment objective. This means that the Underlying Fund does not try to beat the index it tracks (the Underlying Index) and does not seek temporary defensive positions when markets decline or appear overvalued. BFA uses a representative sampling indexing strategy to manage each Underlying Fund, meaning that it invests in a representative sample of securities that collectively have an investment profile similar to that of the applicable Underlying Index. An Underlying Fund also may invest in securities not included in the Underlying Index which BFA believes may help such Underlying Fund to track its Underlying Index. BFA believes that indexing may eliminate the chance that an Underlying Fund will substantially underperform its Underlying Index, but also may reduce some of the risks of active management, such as poor security selection. BFAs indexing approach seeks to achieve lower costs by keeping portfolio turnover low in comparison to actively managed mutual funds. In order to provide the Fund with diversified investment exposure to various types of fixed-income securities, the Funds subadviser, which is an affiliate of BFA, selects Underlying Funds that themselves invest in different types of fixed-income securities, such as bonds issued by the U.S. or foreign governments, bonds and other debt securities issued by U.S. or foreign corporations, mortgage-backed securities and asset-backed securities. The Funds average portfolio duration, average credit quality and the proportion of U.S. versus foreign securities may vary based on the subadvisers forecast of interest rates, yield curve analysis and other market factors consistent with the Funds objective to seek total return. The subadviser generally sells shares of Underlying Funds in order to meet or change Underlying Fund allocations or in response to shareholder redemptions. The Fund is designed for investors who are comfortable with assuming the risks associated with investing in bonds and other fixed-income securities. The Underlying Funds may lend their portfolio securities to generate additional income. The Underlying Funds also may, when consistent with their investment objectives, use certain futures, options and swap contracts (collectively, commonly known as derivatives), either for hedging purposes or to increase returns. Although the Fund seeks to provide diversification across traditional fixed-income asset classes, the Fund invests a significant portion of its assets in a small number of issuers (i.e., one or more Underlying Funds). However, many of the Underlying Funds in which the Fund invests are diversified. The Underlying Funds will concentrate their investments in a particular industry, group of industries or market sector to approximately the same extent that the applicable Underlying Index is concentrated. Show less