Strategy. The Fund seeks to track the investment results of the S&P MidCap 400 Sustainability Screened Index (the Underlying Index ), which measures the performance of the mid-capitalization sector of the U.S. equity market while excluding companies involved in controversial business activities and controversies, as determined by S&P Dow Jones Indices LLC (the Index Provider or SPDJI ). The Underlying Index is a float-adjusted market capitalization-weighted equity index. The Index Provider constructs the Underlying Index starting with the S&P MidCap 400 and, based on its eligibility criteria, excludes companies with specific levels of involvement in the business of tobacco (both production and retail), controversial weapons, manufacturers and major retailers of small arms and companies involved in certain fossil-fuel related activity. The … Show more… The Fund seeks to track the investment results of the S&P MidCap 400 Sustainability Screened Index (the Underlying Index ), which measures the performance of the mid-capitalization sector of the U.S. equity market while excluding companies involved in controversial business activities and controversies, as determined by S&P Dow Jones Indices LLC (the Index Provider or SPDJI ). The Underlying Index is a float-adjusted market capitalization-weighted equity index. The Index Provider constructs the Underlying Index starting with the S&P MidCap 400 and, based on its eligibility criteria, excludes companies with specific levels of involvement in the business of tobacco (both production and retail), controversial weapons, manufacturers and major retailers of small arms and companies involved in certain fossil-fuel related activity. The Index Provider uses data and research analysis from Trucost, S&P Global Business Involvement Screens, Sustainalytics, RepRisk and SAM ESG Research ( SAM ) to identify a companys involvement in certain controversial business activities and controversies. Companies with fossil fuel reserves from thermal coal, other coal, conventional and unconventional oil, natural gas, shale gas and other unspecified oil & gas sources, as defined and measured by Trucost, are excluded from the eligible universe of companies. Additionally, the following types of companies with specific levels of involvement based on revenue or ownership, as specified and measured by S&P Global Business Involvement Screens, are excluded from the eligible universe of companies: controversial weapons, small arms, tobacco products, oil sands, shale energy and thermal coal. Companies identified and deemed by Sustainalytics to be non-compliant with the United Nations Global Compact (the UNGC ) are excluded from the eligible universe of companies. In addition to the aforementioned exclusions, the Index Provider uses RepRisk, a provider of business intelligence on environmental, social and governance risks, for screening and analysis of controversies related to companies within the Underlying Index. In cases where risks are presented, SAM releases a Media and Stakeholder Analysis ( MSA ), which includes a range of issues such as economic crime and corruption, fraud, illegal commercial practices, human rights issues, labor disputes, workplace safety, catastrophic accidents, and environmental disasters. SPDJIs Index Committee reviews constituents that have been identified by SAMs MSA to evaluate the potential impact of controversial company activities and may decide to remove a company from the Underlying Index. In the event of a removal, the company would not be eligible for reentry into the Underlying Index for one full calendar year beginning with the subsequent rebalancing. The Underlying Index rebalances quarterly, effective after the close of the third Friday of March, June, September and December. Exclusions applied to the Underlying Index are reviewed at each rebalancing reference date which is the third Friday of February, May, August and November respectively. As of March 31, 2025, a significant portion of the Underlying Index is represented by securities of companies in the financials and industrials industries or sectors. 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 that collectively has an investment profile similar to that of an applicable underlying index. The securities selected are expected to have, in the aggregate, investment characteristics (based on factors such as market capitalization and industry weightings), fundamental characteristics (such as return variability and yield) and liquidity measures similar to those of an applicable underlying index. The Fund may or may not hold all of the securities in the Underlying Index. The Fund generally will invest at least 90% of its assets in the component securities of the Underlying Index and may invest up to 10% of its assets in certain futures, options and swap contracts, cash and cash equivalents, including shares of money market funds advised by BFA or its affiliates, as well as in securities not 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 a product of SPDJI, which is ? independent of the Fund and BFA. The Index Provider determines the composition and relative weightings of the securities in 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) and repurchase agreements collateralized by U.S. government securities are not considered to be issued by members of any industry. Show less