Strategy. The Fund seeks to track the investment results of the ICE BofA BB US High Yield Constrained Index (the Underlying Index ), which measures the performance of the BB (or its equivalent) fixed-rate, U.S. dollar-denominated, corporate bond market. The Underlying Index is a subset of the ICE BofA US High Yield Index that is market capitalization-weighted with a 2% cap on any one issuer and a pro rata distribution of any excess weight across the remaining issuers in the Underlying Index. The Underlying Index includes U.S. dollar-denominated securities issued by U.S. and non-U.S. industrials, utility and financial corporate issuers, with maturities of one year or more, that have $250 million or more of outstanding face value. Only securities rated BB+ … Show more… The Fund seeks to track the investment results of the ICE BofA BB US High Yield Constrained Index (the Underlying Index ), which measures the performance of the BB (or its equivalent) fixed-rate, U.S. dollar-denominated, corporate bond market. The Underlying Index is a subset of the ICE BofA US High Yield Index that is market capitalization-weighted with a 2% cap on any one issuer and a pro rata distribution of any excess weight across the remaining issuers in the Underlying Index. The Underlying Index includes U.S. dollar-denominated securities issued by U.S. and non-U.S. industrials, utility and financial corporate issuers, with maturities of one year or more, that have $250 million or more of outstanding face value. Only securities rated BB+ through BB-, based on an average of Moodys Investors Service, Inc. ( Moodys ), Fitch Ratings, Inc. ( Fitch ), and S&P Global Ratings, are eligible for the Underlying Index. Securities rated BB+ and below are generally considered non-investment grade (commonly referred to as junk bonds ). The securities in the Underlying Index are updated on the last calendar day of each month. Excluded from the Underlying Index are certain hybrid capital securities, securities issued or marketed primarily to retail investors, equity-linked securities, securities in legal default, hybrid securitized corporates, eurodollar bonds, taxable and tax-exempt US municipal securities and $1000 par preferred and dividends received deduction-eligible securities. The Fund will invest in non-U.S. issuers to the extent necessary for it to track the Underlying Index. The Fund may invest in privately issued securities, including those that are normally purchased pursuant to Rule 144A or Regulation S promulgated under the Securities Act of 1933, as amended (the 1933 Act ). As of October 31, 2025, a significant portion of the Underlying Index is represented by securities of companies in the industrials industry or sector. The components of the Underlying Index, and the degree to which these components represent certain industries, are likely to change over time. BFA uses an indexing approach to try to achieve the Funds investment objective. 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 or other instruments that collectively has an investment profile similar to that of an applicable underlying index. The instruments 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 ( i.e. , an instrument's price sensitivity to a change in interest rates), maturity or 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 components of the Underlying Index. The Fund will invest at least 80% of its assets in the component securities of the Underlying Index, and the Fund will invest at least 90% of its assets in fixed income securities of the types included in the Underlying Index that BFA believes will help the Fund track the Underlying Index. The Fund will invest no more than 10% of its assets in futures, options and swaps contracts that BFA believes will help the Fund track the Underlying Index as well as in fixed income securities other than the types included in the Underlying Index, but which BFA believes will help the Fund track the Underlying Index. Cash and cash equivalent investments associated with a derivative position will be treated as part of that position for the purposes of calculating the percentage of investments included in the Underlying Index. The Fund seeks to track the investment results of the Underlying Index before fees and expenses of the Fund. The Fund may lend securities representing up to one-third of the value of the Fund's total assets (including the value of any collateral received). The Underlying Index is owned, maintained and administered by ICE Data Indices, LLC (the Index Provider or IDI ), which is ? independent of the Fund and BFA. The Index Provider determines the composition and relative weightings of the components of 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. Show less