Strategy. The Fund seeks to track the investment results of the Bloomberg MSCI USD Green Bond Select Index (the Underlying Index ), which measures the performance of U.S. dollar-denominated investment-grade (as determined by Bloomberg Index Services Limited, a subsidiary of Bloomberg Finance L.P. and its affiliates (the Index Provider or Bloomberg )) green bonds issued by U.S. and non-U.S. issuers to fund projects with direct environmental benefits. Green bonds are fixed income securities whose proceeds are exclusively applied to projects or activities that promote climate or other environmental sustainability purposes. For inclusion in the Underlying Index, securities are independently evaluated by MSCI Solutions LLC ( MSCI Solutions ), pursuant to an agreement between MSCI Solutions and the Index Provider (or an … Show more… The Fund seeks to track the investment results of the Bloomberg MSCI USD Green Bond Select Index (the Underlying Index ), which measures the performance of U.S. dollar-denominated investment-grade (as determined by Bloomberg Index Services Limited, a subsidiary of Bloomberg Finance L.P. and its affiliates (the Index Provider or Bloomberg )) green bonds issued by U.S. and non-U.S. issuers to fund projects with direct environmental benefits. Green bonds are fixed income securities whose proceeds are exclusively applied to projects or activities that promote climate or other environmental sustainability purposes. For inclusion in the Underlying Index, securities are independently evaluated by MSCI Solutions LLC ( MSCI Solutions ), pursuant to an agreement between MSCI Solutions and the Index Provider (or an affiliate), based on four criteria aligned with themes articulated in the Green Bond Principles, which are published by the International Capital Market Association ( Green Bond Principles ). The first criterion is whether the use of proceeds falls within at least one of six eligible environmental categories defined by MSCI Solutions: alternative energy, energy efficiency, pollution prevention and control, sustainable water, green building and climate adaption. Other environmental activities that do not fit into these categories ( e.g ., sustainable forestry) may also be candidates for inclusion based on evaluations by MSCI Solutions. The remaining three criteria for evaluation and inclusion in the Underlying Index are processes for green project evaluation and selection, processes for the management of proceeds and a commitment to ongoing reporting of the environmental impact of the use of proceeds. Self-labeled green bonds are evaluated for potential inclusion in the Underlying Index using the four criteria. Meeting all four criteria is required for bonds issued after the publication of the Green Bond Principles in January 2014. Self-labeled green bonds issued prior to 2014 may still qualify for the Underlying Index so long as they meet the use of proceeds criterion, since no formal guidelines were available at the time of issuance. General purpose bonds from issuers that are considered by the Index Provider to be a pure-play green company (defined as a legal entity with greater than 90% of activities, as measured by revenues, within one or more of the eligible environmental categories) must meet all four criteria to be eligible. The Underlying Index includes sovereign and government-related debt, corporate bonds and securitized bonds denominated in U.S. dollars from both developed and emerging market issuers. Eligible securities include, among others, fixed-rate coupon bonds; bonds that convert from fixed to floating rate (including fixed-to-float perpetuals); senior and subordinated securities; fixed-rate bullet, putable, sinkable/amortizing and callable bonds; taxable municipal securities; original issue zero coupon bonds; certificates of deposit; loan participation notes; and U.S. agency commercial mortgage-backed securities. Fixed-to-floating rate bonds are eligible during their fixed-rate term only. Certain types of securities are excluded from the Underlying Index, including, among others, contingent capital securities, bonds with equity-type features ( e.g ., warrants, convertibles and preferreds), inflation-linked bonds, floating-rate issues, fixed-rate perpetuals, tax-exempt municipal securities, private placements (other than those offered pursuant to Rule 144A or Regulation S promulgated under the Securities Act of 1933, as amended (the 1933 Act )), retail bonds and structured notes. The Underlying Index does not have a one-year minimum time to maturity requirement and holds bonds until final maturity. As of October 31, 2025, the weighted average duration of the securities in the Underlying Index was 5.01 years, and the weighted average maturity of the securities in the Underlying Index was 7.27 years. The securities in the Underlying Index are weighted using an issuer capping methodology that sets a 23.75% cap on the aggregate weight of all large issuers, which are defined by the Index Provider as individually having at least 4.75% of the market value of the uncapped index. Small issuers, defined as individually having less than 4.75% of the market value of the uncapped index, are individually capped at 4.75% of the Underlying Index. The excess market value over the caps is redistributed on a pro rata basis to all other issuers bonds that are under the caps until no limits are breached. This methodology is applied at each rebalancing, which occurs on the last business day of each month. As of October 31, 2025, the Underlying Index was composed of approximately 338 securities issued by entities in the following 23 countries or regions as well as securities issued or guaranteed by supranational entities: Canada, Chile, China, Denmark, Finland, France, Germany, Hong Kong, Hungary, India, Indonesia, Israel, Japan, Kuwait, the Netherlands, Peru, Portugal, Qatar, Saudi Arabia, South Korea, Sweden, the United Arab Emirates and the U.S. As of October 31, 2025, a significant portion of the Underlying Index is represented by the bonds of issuers in the financial services and utilities industries or sectors and sovereign and quasi-sovereign securities. The components of the Underlying Index 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 sponsored by Bloomberg, MSCI Solutions, or their affiliates, which are ? 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