Strategy. In seeking to track the performance of the Bloomberg SASB US Corporate ESG Ex-Controversies Select Index (the Index), the Fund employs a sampling strategy, which means that the Fund is not required to purchase all of the securities represented in the Index. Instead, the Fund may purchase a subset of the securities in the Index in an effort to hold a portfolio of securities with generally the same risk and return characteristics of the Index. The quantity of holdings in the Fund will be based on a number of factors, including asset size of the Fund. Based on its analysis of these factors, SSGA Funds Management, Inc. (SSGA FM or the Adviser), the investment adviser to the Fund, either may … Show more… In seeking to track the performance of the Bloomberg SASB US Corporate ESG Ex-Controversies Select Index (the Index), the Fund employs a sampling strategy, which means that the Fund is not required to purchase all of the securities represented in the Index. Instead, the Fund may purchase a subset of the securities in the Index in an effort to hold a portfolio of securities with generally the same risk and return characteristics of the Index. The quantity of holdings in the Fund will be based on a number of factors, including asset size of the Fund. Based on its analysis of these factors, SSGA Funds Management, Inc. (SSGA FM or the Adviser), the investment adviser to the Fund, either may invest the Fund's assets in a subset of securities in the Index or may invest the Fund's assets in substantially all of the securities represented in the Index in approximately the same proportions as the Index, as determined by the Adviser to be in the best interest of the Fund in pursuing its objective. Under normal market conditions, the Fund generally invests substantially all, but at least 80%, of its total assets in the securities comprising the Index or in securities that the Adviser determines have economic characteristics that are substantially identical to the economic characteristics of the securities that comprise the Index. In addition, in seeking to track the Index, the Fund may invest in debt securities that are not included in the Index, cash and cash equivalents or money market instruments, such as repurchase agreements and money market funds (including money market funds advised by the Adviser). In seeking to track the Index, the Fund's assets may be concentrated in an industry or group of industries, but only to the extent the Index concentrates in a particular industry or group of industries. The Fund may use derivatives, including credit default swaps and credit default index swaps, to obtain investment exposure that the Adviser expects to correlate closely with the Index, or a portion of the Index, and in managing cash flows. The Index is designed to measure the performance of investment grade corporate bonds issued by companies that exhibit certain environmental, social and governance characteristics, while also exhibiting risk and return characteristics that are comparable to those of the Bloomberg US Corporate Index (the Parent Index). The Parent Index represents publicly issued, investment grade, fixed-rate, taxable, U.S. dollar-denominated corporate bonds issued by U.S. and non-U.S. industrial, utility, and financial institutions that have a remaining maturity of greater than or equal to 1 year and have $300 million or more of par amount outstanding. The Index incorporates ESG criteria to screen securities within the Parent Index for which data is available (as discussed further below), and assign scores to the remaining securities. The scoring system that is utilized by the Index, the Responsibility or R-Factor TM score, was developed by State Street Global Advisors. The R-Factor TM score measures the performance of a company's business operations and governance as related to financially material ESG challenges facing the issuer's industry. The R-Factor TM score draws on a number of data sources that provide data metrics on a variety of ESG topics. The R-Factor TM scoring process comprises two underlying components, an ESG component and a corporate governance component. The ESG component is based on the framework published by the Sustainability Accounting Standards Board (SASB), which attempts to identify ESG issues that are financially material to an issuer based on its industry classification. The ESG component of the R-Factor TM score is determined using only those metrics from data sources that specifically address such issues. The corporate governance component of the score is generated using region-specific corporate governance codes developed by investors or regulators that describe minimum corporate governance expectations of a particular region. The governance codes typically address topics such as shareholder rights, board independence and executive compensation. The corporate governance component uses data provided by data sources to assign a corporate governance score according to these governance codes. To construct the Index, the Parent Index is first screened to remove securities of issuers involved in, and/or which derive significant revenue (as determined by the Index Provider (as defined below)) from, certain practices, industries or product lines, including: Extreme Event Controversies, Controversial Weapons, UN Global Compact Violations, Civilian Firearms, Thermal Coal Extraction and Tobacco (collectively, Controversial Categories). The Index Provider incorporates data drawn from a number of sources for applying the screen; however, this data may not be available for certain issuers of securities in the Parent Index. The remaining securities, which may include securities of issuers for which Controversial Categories data is not available, are then further screened to remove all companies without an R-Factor TM score. All remaining securities are considered the investable universe. The final portfolio of securities in the Index is then constructed utilizing an optimizer that deploys a quantitative process to select constituents and their weights to maximize the Index's overall R-Factor TM score while minimizing active total risk versus the Parent Index. As of August 31, 2022, a significant portion of the Fund comprised companies in the financial and industrial sectors, although this may change from time to time. As of July 31, 2022, the Index comprised 3,438 securities. The Index is rebalanced and reconstituted on the last business day of each month. The Index is sponsored by Bloomberg Index Services Limited (the Index Provider), which is not affiliated with the Fund or the Adviser. The Index Provider determines the composition of the Index, relative weightings of the securities in the Index and publishes information regarding the market value of the Index. Show less