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S000065837 [Member] Investment Strategy - FlexShares US Quality Low Volatility Index Fund
Oct. 31, 2025
Prospectus [Line Items]  
Strategy [Heading] Principal Investment Strategies
Strategy Narrative [Text Block]
The Underlying Index is designed to construct a high quality universe of companies, that in aggregate, possess lower overall absolute volatility characteristics relative to the Northern Trust 1250 Index (the “Parent Index”), a float-adjusted market capitalization weighted index of U.S. domiciled large- and mid-capitalization companies. The Underlying Index places an emphasis on a company’s income and capital growth, while also reducing overall volatility of returns relative to the Parent Index.
To derive the Underlying Index, NTI, acting in its capacity as the index provider (the “Index Provider”) ranks all constituents of the Parent Index using a Northern Trust proprietary quality factor. This factor is a quantitative ranking based on: (a) management efficiency (e.g., corporate finance activities); (b) profitability (e.g., reliability and sustainability of financial performance); and (c) cash flow (e.g., cash flow generation). The Index Provider then excludes the lowest quintile of constituents ranked according to the quality factor and uses an optimization process to select and weight eligible securities in order to (a) seek to reduce overall portfolio volatility and (b) maximize the
overall quality factor relative to the Parent Index. The optimization also includes sector, industry group, style factor, single-security weight, historical beta (i.e., market sensitivity, relative to the Parent Index), liquidity and turnover constraints so that these characteristics of the Underlying Index vary within acceptable bands relative to the Parent Index.
As of December 31, 2025, the Underlying Index was comprised of 108 constituent securities with market capitalizations ranging from $4.0 billion to $4.5 trillion. The Underlying Index is reconstituted quarterly. The Fund generally reconstitutes its portfolio in accordance with the Underlying Index.
 NTI uses a “passive” or indexing approach to try to achieve the Fund’s investment objective. Unlike many investment companies, the Fund does not try to “beat” the index it tracks and does not seek temporary defensive positions when markets decline or appear overvalued.
NTI uses a representative sampling strategy to manage the Fund. “Representative sampling” is investing in a representative sample of securities that collectively has an investment profile similar to the Underlying Index. The Fund may or may not hold all of the securities that are included in the Underlying Index. The Fund reserves the right to invest in substantially all of the securities in its Underlying Index in approximately the same proportions (i.e., replication) if NTI determines that it is in the best interest of the Fund.
Under normal circumstances, the Fund will invest at least 80% of its total assets (exclusive of collateral held from securities lending) in the securities of the Underlying Index. The Fund may also invest up to 20% of its assets in cash and cash equivalents, including shares of money market funds advised by NTI or its affiliates, futures contracts and options on futures contracts, as well as securities not included in the Underlying Index, but which NTI believes will help the Fund track its Underlying Index.
The Underlying Index is created and sponsored by NTI, as the Index Provider. NTI also serves as the investment adviser to the Fund. 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.
The Fund may lend securities representing up to one-third of the value of the Fund’s total assets (including the value of the collateral received).
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. As of December 31, 2025, the Underlying Index was concentrated in the Information Technology sector. The components of the Underlying Index, and the degree to which these components represent certain industries or sectors, may change over time.
Strategy Portfolio Concentration [Text] 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. As of December 31, 2025, the Underlying Index was concentrated in the Information Technology sector. The components of the Underlying Index, and the degree to which these components represent certain industries or sectors, may change over time.