FlexShares Trust

FlexShares® Core Select Bond Fund

Ticker: BNDC

Investment Objective

The Fund seeks total return and preservation of capital.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy, hold and sell shares of the Fund. Under the Fund’s Investment Advisory Agreement, the Fund is responsible for the following expenses: interest expenses, brokerage commissions and other trading expenses, fees and expenses of the independent trustees and their independent legal counsel, taxes and other extraordinary costs such as litigation and other expenses not incurred in the ordinary course of business. You will also incur usual and customary brokerage commissions and fees to financial intermediaries when buying or selling shares of the Fund in the secondary market, which are not reflected in the example that follows:


Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Management Fees	0.35%
Distribution (12b-1) Fees	0.00%
Other Expenses	0.01%
Acquired Fund Fees and Expenses(1)	0.20%
Total Annual Fund Operating Expenses	0.56%
Expense Reimbursement(2)	-0.21%
Total Annual Fund Operating Expenses After Expense Reimbursement	0.35%

(1)

The "Total Annual Fund Operating Expenses" may not correlate to the ratio of expenses to average net assets as reported in the "Financial Highlights" section of the Prospectus, which reflects the operating expenses of the Fund and does include "Acquired Fund Fees and Expenses."

(2)

Northern Trust Investments, Inc. (“NTI”) has contractually agreed to reimburse a portion of the operating expenses of the Fund (other than 12b-1 Fees, Tax Expenses, Extraordinary Expenses, and Acquired Fund Fees and Expenses to the extent the “Total Annual Fund Operating Expenses” exceed 0.35%. This contractual limitation may not be terminated before March 1, 2024 without the approval of the Fund’s Board of Trustees. NTI has also contractually agreed to waive Management Fees or reimburse certain expenses in an amount equal to the sum of (a) any Acquired Fund Fees and Expenses, if any, incurred by the Fund that are attributable to the Fund’s investment in Acquired Funds managed by NTI or an investment adviser controlling, controlled by, or under common control with NTI (“Affiliated Funds”); and (b) 0.05% or such lesser amount in Acquired Fund Fees and Expenses incurred by the Fund that are attributable to the Fund’s investment in Acquired Funds that are not Affiliated Funds, until March 1, 2024. The Trust’s Board of

Trustees may terminate the contractual arrangements at any time if it determines that it is in the best interest of the Fund and its shareholders.

Example

The following Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same (taking into account the expense reimbursement arrangement for one year). Although your actual costs may be higher or lower, based on these assumptions your costs would be:


1 Year	$36
3 Years	$ 158
5 Years	$292
10 Years	$681

Portfolio Turnover. The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. Portfolio turnover may vary from year to year, as well as within a year. During the most recent fiscal year, the Fund’s portfolio turnover rate was 121% of the average value of its portfolio.

Principal Investment Strategies

The Fund seeks to achieve its investment objective by investing, under normal circumstances, at least 80% of its net assets in U.S. dollar-denominated investment-grade fixed-income securities either directly or indirectly through exchange-traded funds ("ETFs") and other registered investment companies (together with ETFs, “Underlying Funds”). The Fund primarily invests in fixed-income securities of varying maturities, including bonds, debt securities and other similar instruments issued by U.S. public and U.S and non-U.S. private sector entities. Such issuers include, without limitation, U.S. governments and their agencies, instrumentalities or sponsored enterprises, and

FlexShares® Core Select Bond Fund (cont.)

U.S. and non-U.S. private-sector entities, such as corporations and banks. The Fund may invest in fixed income securities of any maturity.

The Fund seeks to provide attractive risk-adjusted performance by investing in a portfolio of fixed-income securities and Underlying Funds. The Fund generally adjusts its allocations to securities based on NTI’s assessment of potential changes in interest rate levels, the shape of the yield curve and credit spread relationships. The Fund also seeks to balance the potential for return and risk while emphasizing liquidity and diversification across a spectrum of U.S. dollar-denominated investment-grade fixed income securities.

The Fund may invest, without limitation, in mortgage- or asset-backed securities, including to-be-announced (“TBA”) transactions, and purchase and sell securities on a when-issued, delayed delivery or forward commitment basis. The Fund also may, without limitation, seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts (such as buy backs or mortgage dollar rolls).

When necessary or appropriate to manage the Fund’s exposure to interest-rate risks, the Fund may take short or long positions in U.S. Treasury futures or transact in interest rate swaps. The Fund’s short positions in U.S. Treasury futures are not intended to mitigate credit spread risk or other factors influencing the price of non-government bonds, which may have a greater impact than interest rates. The Fund may also invest in other interest rate futures contracts, including, but not limited to, Eurodollar and Federal Funds futures.

The Fund may invest in short-term paper, cash and cash equivalents, including shares of affiliated and unaffiliated money market funds, in order to achieve its investment objective.

The Fund may make the foregoing investments either directly or indirectly by investing in Underlying Funds, such as indexed or actively managed ETFs or other registered investment companies that invest in such securities. The Underlying Funds in which the Fund may invest include funds managed by NTI or its affiliates.

The Fund is an actively managed ETF that does not seek to replicate the performance of a specified index. The Fund may have a higher degree of portfolio turnover than funds that seek to replicate the performance of an 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).

Principal Risks

As with any investment, you could lose all or part of your investment in the Fund, and the Fund’s performance could trail that of other investments. The Fund is subject to certain risks, including the principal risks noted below, any of which may adversely affect the Fund’s net asset value (“NAV”), trading price, yield, total return and ability to meet its investment objective. Because the Fund may significantly invest in Underlying Funds, the risks described below are also applicable to the Underlying Funds, and to the extent that the Fund invests directly in securities and other instruments, the risks described below are also directly applicable to the Fund. Each risk noted below is considered a principal risk of investing in the Fund, regardless of the order in which it appears. The significance of each risk factor below may change over time and you should review each risk factor carefully.

Management Risk is the risk that a strategy used by NTI may fail to produce the intended results or that imperfections, errors or limitations in the tools and data used by NTI may cause unintended results.

Underlying Fund Risk is the risk that the Fund’s investment performance and its ability to achieve its investment objective may be directly related to the performance of the Underlying Funds in which it invests. There can be no assurance that the Underlying Funds will achieve their respective investment objectives. The Fund is subject to the risks of the Underlying Funds in direct proportion to the allocation of its assets among the Underlying Funds. By investing in the Underlying Funds indirectly through the Fund, you will incur not only a proportionate share of the expenses of the Underlying Fund held by the Fund (including operating costs and investment management fees), but also expenses of the Fund.

Sampling Risk is the risk that the index-based ETFs in which the Fund invests may utilize a representative sampling approach to track their respective underlying indices. ETFs that utilize a representative sampling approach are subject to an increased risk of tracking error because the securities selected for the ETF in the aggregate may vary

FlexShares® Core Select Bond Fund (cont.)

from the investment profile of the underlying index. Additionally, if using a representative sampling approach, an ETF will typically hold a smaller number of securities than the underlying index, and as a result, an adverse development to an issuer of securities that the ETF holds could result in a greater decline in NAV than would be the case if the ETF held all of the securities in the underlying index.

Tracking Risk is the risk that the index-based ETFs and other investment companies in which the Fund invests may not be able to replicate exactly the performance of the indices they track as a result of share purchases and redemptions, transaction costs, expenses and other factors. In addition, index-based ETFs and other investment companies in which the Fund invests may incur expenses not incurred by their applicable indices. Certain securities comprising the indices may, from time to time, temporarily be unavailable, which may further impede an ETF’s or other investment company’s ability to track its applicable index or match its performance.

Market Risk is the risk that the value of the Fund’s investments may increase or decrease in response to expected, real or perceived economic, political or financial events in the U.S. or global markets. The frequency and magnitude of such changes in value cannot be predicted. Certain securities and other investments held by the Fund may experience increased volatility, illiquidity, or other potentially adverse effects in response to changing market conditions, inflation, changes in interest rates, lack of liquidity in the bond or equity markets, or volatility in the equity markets. Market disruptions caused by local or regional events such as war, acts of terrorism, the spread of infectious illness (including epidemics and pandemics) or other public health issues, recessions or other events or adverse investor sentiment could have a significant impact on the Fund and its investments and could result in the Fund’s shares trading at increased premiums or discounts to the Fund’s NAV. During periods of market disruption or other abnormal market conditions, the Fund’s exposure to the risks described elsewhere in this summary will likely increase.

Income Risk is the risk that the Fund’s income may decline when interest rates fall. This decline can occur because the Fund must invest in lower-yielding bonds as bonds in its portfolio mature, bonds in an Underlying Fund’s underlying index are substituted or the Fund otherwise needs to purchase additional bonds.

Asset-Backed and Mortgage-Backed Securities Risk. Asset-backed and mortgage-backed securities may be less liquid than other bonds, and may be more sensitive than other bonds to the market’s perception of issuers and creditworthiness of payees, particularly in declining general economic conditions when concern regarding mortgagees’ ability to pay (e.g., the ability of homeowners, commercial mortgagees, consumers with student loans, automobile loans or credit card debtholders to make payments on the underlying loan pools) rises, which may result in the Fund experiencing difficulty selling or valuing these securities. In addition, these securities may not be backed by the full faith and credit of the U.S. government, have experienced extraordinary weakness and volatility at various times in recent years, and may decline quickly in the event of a substantial economic or market downturn. Those asset-backed and mortgage-backed securities that are guaranteed as to the timely payment of interest and principal by a government entity, are not guaranteed as to market price, which will fluctuate. Small movements in interest rates (both increases and decreases) may quickly and significantly reduce the value of certain asset-backed and mortgage-backed securities.

Authorized Participant Concentration Risk is the risk that the Fund may be adversely affected because it has a limited number of institutions that act as authorized participants (“Authorized Participants”). Only an Authorized Participant may engage in creation or redemption transactions directly with the Fund and none of those Authorized Participants is obligated to engage in creation and/or redemption transactions. To the extent that these institutions exit the business or are unable or unwilling to proceed with creation and/or redemption orders with respect to the Fund and no other Authorized Participant is able or willing to step forward to create or redeem Creation Units (as defined below), Fund shares may trade at a discount to NAV and possibly face trading halts and/or delisting.

Market Trading Risk is the risk that the Fund faces because its shares are listed on a securities exchange, including the potential lack of an active market for Fund shares, losses from trading in secondary markets, periods of high volatility and disruption in the creation/redemption process of the Fund. ANY OF THESE FACTORS MAY LEAD TO THE FUND’S SHARES TRADING AT A PREMIUM OR DISCOUNT TO NAV.

FlexShares® Core Select Bond Fund (cont.)

Trading in Fund shares may be halted due to market conditions or for reasons that, in the view of its listing exchange, make trading in the shares inadvisable. The market price of Fund shares will generally fluctuate in accordance with changes in its NAV, changes in the relative supply of, and demand for, Fund shares, and changes in the liquidity or perceived liquidity, of the Fund’s holdings.

Credit (or Default) Risk is the risk that the inability or unwillingness of an issuer or guarantor of a fixed-income security, or a counterparty to a TBA, repurchase or other transaction, to meet its payment or other financial obligations will adversely affect the value of the Fund’s investments and its returns. The credit quality of a debt security or of the issuer of a debt security held by the Fund could deteriorate rapidly, which may impair the Fund's liquidity or cause a deterioration in the Fund's NAV. The Fund could also be delayed or hindered in its enforcement of rights against an issuer, guarantor or counterparty. The degree of credit risk depends on the issuer’s or counterparty’s financial condition and on the terms of the securities.

Debt Extension Risk is the risk that when interest rates rise an issuer will exercise its right to pay principal on certain debt securities held by the Fund later than expected. This will cause the value of the security, and the Fund’s NAV, to decrease, and the Fund may lose opportunities to invest in higher yielding securities.

Derivatives Risk is the risk that derivatives may pose risks in addition to and greater than those associated with investing directly in securities, currencies and other instruments, may be illiquid or less liquid, more volatile, more difficult to value and leveraged so that small changes in the value of the underlying instrument may produce disproportionate losses to the Fund. Derivatives are also subject to counterparty risk, which is the risk that the other party to the transaction will not perform its contractual obligations. The use of derivatives is a highly specialized activity that involves investment techniques and risks different from those associated with investments in more traditional securities and instruments.

•Futures Contracts Risk is the risk that there will be imperfect correlation between the change in market value of the Fund’s securities and the price of futures contracts, which may result in the strategy not working

as intended; the possible inability of the Fund to sell or close out a futures contract at the desired time or price; losses due to unanticipated market movements, which potentially are unlimited; and the possible inability of NTI to correctly predict the direction of securities’ prices, interest rates, currency exchange rates and other economic factors, which may make the Fund’s returns more volatile or increase the risk of loss.

•Swap Contracts Risk Swap contracts involve the risk that the counterparty with whom the Fund has entered into the agreement will default on its obligation to pay the Fund. While certain swaps are subject to mandatory central clearing, which is intended to reduce counterparty risk, these swaps are subject to the risk that a central clearinghouse will go into bankruptcy or become non-operational, and sometimes involve increased transaction costs.

Sector Risk is the risk that companies in similar businesses may be similarly affected by particular economic or market events, which may, in certain circumstances, cause the value of securities of all companies in a particular sector of the market to decrease.

Hedging Risk is the risk that the Fund’s short positions in U.S. Treasury futures and transactions in interest rate swaps will not completely eliminate interest rate risk of long positions in bonds. The Fund seeks to mitigate the potential impact of interest rates on the performance of bonds by entering into short positions in U.S. Treasury futures or transact in interest rate swaps. The Fund’s short positions in U.S. Treasury futures and interest rate swaps are not intended to mitigate credit spread risk or other factors influencing the price of bonds, which may have a greater impact than interest rates. In addition, when interest rates fall, long-only bond investments will perform better than the Fund’s investments. In certain falling interest rate environments, the Fund’s hedging strategy could result in disproportionately larger losses in the short U.S. Treasury futures and interest rate swaps positions as compared to gains in the long bond positions attributable to interest rate changes. There is no guarantee the Fund will have positive returns, even in environments of sharply rising Treasury interest rates in which the Fund’s short positions might be expected to mitigate the effects of such rises. The Fund will incur expenses when entering into short positions.

High Portfolio Turnover Risk is the risk that active and frequent trading of the Fund’s portfolio securities may

FlexShares® Core Select Bond Fund (cont.)

result in increased transaction costs to the Fund, including brokerage commissions, dealer mark-ups and other transaction costs, which could reduce the Fund’s return.

Interest Rate/Maturity Risk is the risk that the value of the Fund’s fixed-income assets will decline because of rising interest rates. In general, securities with longer maturities or durations are more sensitive to interest rate changes. Changing interest rates, including rates that fall below zero, may have unpredictable effects on the markets and the Fund’s investments, may result in heightened market volatility, may impact the liquidity of fixed-income securities and of the Fund, and may detract from Fund performance. A low or negative interest rate environment could cause the Fund’s earnings to fall below the Fund’s expense ratio, resulting in a negative yield and a decline in the Fund’s share price. An increase in interest rates may cause investors to move out of fixed income securities on a large scale, which could adversely affect the price of fixed income securities, lead to heightened volatility in the fixed-income markets and may adversely affect the liquidity of certain fixed-income investments.

Liquidity Risk is the risk that certain portfolio securities may be less liquid or may become less liquid than others, which may make them difficult or impossible to sell at the time and the price that the Fund would like, adversely affecting the value of the Fund’s investments and its returns. Illiquid investments may be harder to value, especially in changing markets, and if the Fund is forced to sell these investments to meet redemption requests or for other cash needs, the Fund may suffer a loss. Liquidity risk may result from the lack of an active market, reduced number and capacity of traditional market participants to make a market in fixed income securities, and may be magnified in a rising interest rate environment or other circumstances where investor redemptions from fixed income funds may be higher than normal, causing increased supply in the market due to selling activity. The market for certain investments may become illiquid under adverse market or economic conditions independent of any specific adverse changes in the conditions of a particular issuer. Additionally, in adverse market conditions, the Fund’s market price may begin to reflect illiquidity or pricing uncertainty of the Fund’s portfolio securities. This could lead to the Fund’s shares trading at a price that is higher or lower than the Fund’s NAV. At times, such differences may be significant.

Foreign Securities Risk is the risk that investing in foreign (non-U.S.) securities may result in the Fund experiencing more rapid and extreme changes in value than a fund that invests exclusively in securities of U.S. companies, due to less liquid markets and adverse economic, political, diplomatic, financial, and regulatory factors. Foreign governments may impose limitations on foreigners’ ownership of interests in local issuers, restrictions on the ability to repatriate assets, and may also impose taxes. Any of these events could cause the value of the Fund’s investments to decline. Foreign banks, agents and securities depositories that hold the Fund’s foreign assets may be subject to little or no regulatory oversight over, or independent evaluation, of their operations. Additional costs associated with investments in foreign securities may include higher custodial fees than those applicable to domestic custodial arrangements and transaction costs of foreign currency conversions. Unless the Fund has hedged its foreign currency exposure, foreign securities risk also involves the risk of negative foreign currency rate fluctuations, which may cause the value of securities denominated in such foreign currency (or other instruments through which the Fund has exposure to foreign currencies) to decline in value. Currency exchange rates may fluctuate significantly over short periods of time. Currency hedging strategies, if used, are not always successful. For instance, forward foreign currency exchange contracts, if used by the Fund, could reduce performance if there are unanticipated changes in currency exchange rates.

Geographic Risk is the risk that if the Fund invests a significant portion of its total assets in certain issuers within the same country or geographic region, an adverse economic, business or political development affecting that country or region may affect the value of the Fund’s investments more, and the Fund's investments may be more volatile than if the Fund’s investments were not so concentrated in such country or region.

Prepayment (or Call) Risk is the risk that an issuer could exercise its right to pay principal on callable debt securities held by the Fund earlier than expected. Issuers may be more likely to prepay when interest rates fall, when credit spreads change, or when an issuer’s credit quality improves. If this happens, the Fund will not benefit from the rise in the market price of the securities that normally accompanies a decline in interest rates, and will be forced to reinvest

FlexShares® Core Select Bond Fund (cont.)

prepayment proceeds in lower yielding securities, which may reduce the Fund’s returns. The Fund may also lose any premium it paid to purchase the securities.

Securities Lending Risk is the risk that the Fund may lose money because the borrower of the loaned securities fails to return the securities in a timely manner or at all. The Fund could also lose money in the event of a decline in the value of collateral provided for loaned securities or a decline in the value of any investments made with cash collateral.

U.S. Government Securities Risk is the risk that the U.S. government will not provide financial support to its agencies, instrumentalities or sponsored enterprises if it is not obligated to do so by law. Many U.S. government securities that may be purchased by the Fund are not backed by the full faith and credit of the United States. The maximum potential liability of the issuers of some U.S. government securities may greatly exceed their current resources, including any legal right to support from the U.S. Treasury. It is possible that the issuers of such securities will not have the funds to meet their payment obligations in the future.

It is possible to lose money on an investment in the Fund. An investment in the Fund is not a deposit of any bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation, any other government agency, or The Northern Trust Company, its affiliates, subsidiaries or any other bank.

Fund Performance

The bar chart and table that follow show how the Fund has performed on a calendar year basis and provide an indication of the risks of investing in the Fund by showing (A) changes in the Fund’s performance from year to year and (B) how the Fund’s average annual returns compare with those of a broad measure of market performance. Past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated information on the Fund’s performance results can be obtained by visiting flexshares.com.

Calendar Year Total Returns

For the periods in the bar chart above:

Best Quarter (6/30/2020): 4.28%

Worst Quarter (3/31/2022): -6.21%

Average Annual Total Returns

(for the periods ended December 31, 2022)


	One Year	Five Year	Since Inception of Fund	Inception Date of Fund
Before Taxes	-13.55%	-0.08%	0.45%	11/18/2016
After Taxes on Distributions	-14.44%	-1.11%	-0.62%	—
After Taxes on Distributions and Sale of Shares	-8.01%	-0.46%	-0.08%	—
Bloomberg U.S. Aggregate Bond Index*	-13.01%	0.02%	0.61%	—

Reflects no deduction for fees, expenses or taxes.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement plans. After-tax returns may exceed the return before taxes due to an assumed tax benefit from realizing a capital loss on a sale of Fund shares.

Management

Investment Adviser and Portfolio Managers. NTI, a subsidiary of Northern Trust Corporation, serves as the Investment Adviser of the Fund. Morten Olsen and Bilal Memon, each a Senior Vice President of NTI, and Chaitanya

FlexShares® Core Select Bond Fund (cont.)

Mandavakuriti, CFA, a Vice President of NTI, have served as Portfolio Managers of the Fund since September 2020, July 2023 and March 2023, respectively.

Purchase and Sale of Fund Shares

The Fund is an ETF. The Fund’s shares may be issued and redeemed only by certain large institutions, referred to as “Authorized Participants,” that enter into agreements with the Fund’s principal underwriter. Retail investors may acquire and sell Fund shares in the secondary market through a broker-dealer. The price of Fund shares is based on market price, and because ETF shares trade at market prices rather than NAV, shares may trade at a price greater than NAV (a premium) or less than NAV (a discount). An investor may incur costs attributable to the difference between the highest price a buyer is willing to pay to purchase shares of the Fund (bid) and the lowest price a seller is willing to accept for shares of the Fund (ask) when buying or selling shares in the secondary market (“the bid-ask spread”). Recent information, including information about the Fund’s NAV, market price, premiums and discounts, and bid-ask spreads, is included on the Fund’s website at flexshares.com.

Tax Information

The Fund’s distributions are generally taxable to you as ordinary income, capital gains, or a combination of the two, unless you are investing through a tax-advantaged arrangement, such as a 401(k) plan or an individual retirement account. Distributions may be taxable upon withdrawal from tax-advantaged accounts.

Payments to Brokers-Dealers and Other Financial Intermediaries

If you purchase the Fund through a broker-dealer or other financial intermediary (such as a bank), NTI and its related companies may pay the intermediary for activities related to the marketing and promotion of the Fund. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your salesperson to recommend the Fund over another investment. Ask your salesperson or visit your financial intermediary’s website for more information.

Broad-Based Securities Market Indices

THE BLOOMBERG 1-3 MONTH U.S. TREASURY BILL INDEX measures the performance of public obligations of the U.S. Treasury that have a remaining maturity of greater than or equal to 1 month and less than 3 months.

THE BLOOMBERG U.S. AGGREGATE BOND INDEX is a broad-based benchmark that measures the investment grade, U.S. dollar-denominated, fixed-rate taxable bond market, including Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate and hybrid adjustable-rate mortgage pass-throughs), asset-backed securities and commercial mortgage-backed securities.

Additional Fund Information

This Prospectus describes two Funds currently offered by the FlexShares Trust (the “Trust”) and provides information you need to make an informed decision about investing in the Funds. Please read this Prospectus carefully before you make any investment decisions. Additional information regarding the Funds is available at flexshares.com.

Northern Trust Instruments, Inc. (“NTI” or the “Investment Adviser”), is the investment adviser to each Fund. Shares of the Funds are listed for trading on NYSE Arca, Inc. The market price for a share of a Fund may be different from that Fund’s most recent net asset value per share (“NAV”).

Each Fund is actively managed and does not seek to replicate the performance of a specified index. Unlike shares of mutual funds, which can be bought and redeemed from the issuing fund by all shareholders at a price based on NAV, shares of the Funds may be purchased or redeemed directly from the Funds at NAV solely by institutions that act as authorized participants (“Authorized Participants”). Also unlike shares of mutual funds, shares of the Funds are listed on a national securities exchange and trade in the secondary market at market prices that change throughout the day.

Each Fund is designed to be used as part of broader asset allocation strategies. Accordingly, an investment in a Fund should not constitute a complete investment program.

Investors should be aware that the investments made by the Funds and the results achieved by the Funds at any given time are not expected to be the same as those made by other funds for which NTI acts as investment adviser.

Each Fund’s investment objective may be changed without shareholder approval. Shareholders will, however, receive 60 days' prior notice of any material change to the Fund’s investment objective. Any such change may result in a Fund having an investment objective different from the objective that the shareholder considered appropriate at the time of investment in the Fund. On each business day, before commencement of trading on NYSE Arca, each Fund will disclose on flexshares.com the identities and quantities of each Fund’s portfolio holdings that will form the basis for each Fund’s calculation of NAV at the end of the business day.

Additional Fund Information (cont.)

Additional Information About the Funds’ Principal Risks

All investments carry some degree of risk that will affect the value of a Fund’s investments, its investment performance and the price of its shares. As a result, loss of money is a risk of investing in a Fund. This section provides additional information about some of the principal risks of the Funds described under each “Fund Summary” above. A risk may still apply to a Fund although it is not a principal risk of investing in the Fund.

The FlexShares® Core Select Bond Fund may be exposed to these risks directly, or indirectly through the Fund’s investments in exchange-traded funds (“ETFs”) and other registered investment companies (together with ETFs, the “Underlying Funds”).

The table below lists the principal risks that are discussed in each “Fund Summary” above and in this section.

	FlexShares® Ultra-Short Income Fund	FlexShares® Core Select Bond Fund
Asset-Backed and Mortgage-Backed Securities Risk	✓	✓
Authorized Participant Concentration Risk	✓	✓
Cash Transactions Risk	✓
Credit (or Default) Risk	✓	✓
Debt Extension Risk	✓	✓
Derivatives Risk	✓	✓
Emerging Markets Risk	✓
Foreign Securities Risk	✓	✓
Geographic Risk	✓	✓
Hedging Risk		✓
Income Risk	✓	✓
Interest Rate/Maturity Risk	✓	✓
Leveraging Risk	✓
Liquidity Risk	✓	✓
Management Risk	✓	✓
Market Risk	✓	✓
Market Trading Risk	✓	✓
Municipal Market Volatility Risk	✓
Prepayment (or Call) Risk	✓	✓
Securities Lending Risk	✓	✓
Sector Risk	✓	✓

Additional Fund Information (cont.)

	FlexShares® Ultra-Short Income Fund	FlexShares® Core Select Bond Fund
Underlying Fund Risk		✓
U.S. Government Securities Risk	✓	✓
Valuation Risk	✓

Asset-Backed and Mortgage-Backed Securities Risk. Asset-backed securities are sponsored by entities such as government agencies, banks, financial companies and commercial or industrial companies. Asset-backed securities represent participations in, or are secured by and payable from, pools of assets such as mortgages, automobile loans, credit card receivables and other financial assets. In effect, these securities “pass through” the monthly payments that individual borrowers make on their mortgages or other assets net of any fees paid to the issuers. Examples of these include guaranteed mortgage pass-through certificates, collateralized mortgage obligations (“CMOs”) and real estate mortgage investment conduits (“REMICs”). Examples of asset-backed securities that the FlexShares® Ultra-Short Income Fund may invest also include collateralized debt obligations (“CDOs”), which include collateralized bond obligations (“CBOs”), collateralized loan obligations (“CLOs”) and other similarly structured securities. A CBO is a trust typically collateralized by a pool that is backed by a diversified pool of high risk, below-investment grade fixed-income securities. A CLO is a trust typically collateralized by a pool of loans that may include, among others, domestic and foreign senior secured loans, senior unsecured loans, and other subordinate corporate loans, including loans that may be rated below investment grade or equivalent unrated loans.

Asset-backed and mortgage-backed securities are subject to credit, interest rate, prepayment, extension, valuation and liquidity risks.

The value of these securities also may change because of actual or perceived changes in the creditworthiness of the originator, the service agent, the financial institution providing the credit support or the counterparty. Credit supports, if any, generally apply only to a fraction of a security’s value and may be inadequate to protect the investors in

the event of a default. When interest rates rise, the value of an asset-backed security generally will decline. However, when interest rates decline, the value of an asset-backed or mortgage-backed security with prepayment features may not increase as much as that of other fixed-income securities. In addition, non-mortgage asset-backed securities involve certain risks not presented by mortgage-backed securities. Primarily, these securities do not have the benefit of the same security interest in the underlying collateral. If the issuer of the security has no security interest in the related collateral, there is the risk that a Fund could lose money if the issuer defaults. CBOs and CLOs are generally offered in tranches that vary in risk and yield. Both CBOs and CLOs can experience substantial losses due to actual defaults of the underlying collateral, increased sensitivity to defaults due to collateral default and disappearance of junior tranches that protect the more senior tranches, market anticipation of defaults and aversion to CBO or CLO securities as a class. A future economic downturn could increase the risk that such assets underlying asset-backed securities purchased by a Fund will also suffer greater levels of default than were historically experienced. Investments in mortgage-backed securities comprised of subprime mortgages and investments in other asset-backed securities of underperforming assets may be subject to a higher degree of credit risk, valuation risk, and liquidity risk.

Authorized Participant Concentration Risk. Only an Authorized Participant may engage in creation or redemption transactions directly with a Fund. The Funds have a limited number of institutions that act as Authorized Participants and none of those Authorized Participants is obligated to engage in creation and/or redemption transactions. To the extent that these institutions exit the business or are unable or unwilling to proceed with creation and/or redemption orders with respect to a Fund and no other Authorized Participant is able or willing to step forward to

Additional Fund Information (cont.)

create or redeem Creation Units, Fund shares may trade at a discount to NAV and possibly face trading halts and/or delisting. This risk may be heightened for a Fund if it invests in non-U.S. securities or other securities or instruments that are less widely traded. Such securities or instruments often involve greater settlement and operational issues and capital costs for Authorized Participants.

Cash Transactions Risk. Paying redemption proceeds entirely in cash rather than through in-kind delivery of portfolio securities may require a Fund to dispose of or sell portfolio securities or other assets at an inopportune time to obtain the cash needed to meet redemption orders. This may cause the Fund to sell a security or other financial instrument and recognize a capital gain or loss that might not have been incurred if it had not effected a redemption order entirely for cash. As a result, the Fund may pay out higher or lower annual capital gains distributions than ETFs that meet redemption orders entirely in-kind with portfolio securities. The use of all cash creations and redemption orders may also cause the Fund’s shares to trade in the secondary market at wider bid-ask spreads and/or greater premiums or discounts to the Fund’s NAV. To the extent that the maximum additional variable charge for cash creation or cash redemption transactions is insufficient to cover the transaction costs of purchasing or selling portfolio securities, the Fund’s performance could be negatively impacted.

Credit (or Default) Risk. An issuer or guarantor of debt instruments or the counterparty to a derivatives contract, TBA agreement or repurchase agreement may be unable or unwilling to make its timely interest and/or principal payments or to otherwise honor its obligations. Debt instruments are subject to varying degrees of credit risk, which may be reflected in their credit ratings. There is a chance that a Fund’s portfolio holding will have its credit ratings downgraded or will default (i.e., fail to make scheduled interest or principal payments), or that the market’s perception of the issuer’s creditworthiness may worsen, which may reduce a Fund’s income level, impair a Fund’s liquidity, and cause significant deterioration in NAV. The degree of credit risk depends on the issuer’s or counterparty’s financial condition and on the terms of the securities.

In addition, there is no assurance that securities or companies issuing debt that has historically exhibited fundamentals consistent with investment grade ratings will continue to exhibit such fundamentals.

Debt Extension Risk. During periods of rising interest rates, an issuer may exercise its right to pay principal on certain debt securities held by the Fund later than expected. This will cause the value of the security, and the Fund’s NAV, to decrease, and the Fund may lose opportunities to invest in higher yielding securities.

Derivatives Risk. A derivative is a financial instrument whose value is derived from, or based upon, the performance of underlying assets, interest or currency exchange rates, or other indices and may be leveraged. In unusual market circumstances, including periods of increased market volatility, a Fund may make more significant investments in such instruments than it would under normal market conditions.

An investment in derivatives can be more sensitive to changes in interest rates and sudden fluctuations in market prices than conventional securities. Investments in derivative instruments, which may be leveraged, may result in losses exceeding the amounts invested. A Fund’s losses may be greater if it invests in derivatives than if it invests only in conventional securities. Engaging in derivative transactions involves special risks, including that:

(a) the Fund’s derivatives position will lose value;

(b) the counterparty to the transaction will default;

(d) the Fund will be unable to sell its position because of lack of market depth or disruption;

(e) the value of a derivative instrument will be difficult to determine; and

(f) loss will occur as a result of inadequate systems or human error.

Many types of derivatives have been developed recently and have not been tested over complete market cycles. For these reasons, a Fund may suffer a loss whether or not the analysis of the Investment Adviser is accurate.

Additional Fund Information (cont.)

Entering into derivatives contracts may cause the Fund to miss favorable trading opportunities, due to a lack of sufficient cash or readily marketable securities, and may also cause a Fund to realize losses on offsetting or terminated derivative contracts or special transactions.

Forward Foreign Currency Contracts. A forward foreign currency contract is an obligation to exchange one currency for another on a future date at a specified exchange rate. There can be no assurance that appropriate foreign currency transactions will be available for a Fund at any time or that the Fund will enter into such transactions at any time or under any circumstances even if appropriate transactions are available to it. Also, such transactions may not be successful and may eliminate any chance for the Fund to benefit from favorable fluctuations in relevant foreign currencies.

Forward foreign currency contracts are privately negotiated transactions, and can have substantial price volatility. As a result, they offer less protection against default by the other party than is available for instruments traded on an exchange. The institutions that deal in forward foreign currency contracts are not required to continue to make markets in the currencies they trade and these markets can experience periods of illiquidity.

Futures contracts and options on futures contracts. A futures contract is a type of derivative instrument that obligates the holder to buy or sell a specified financial instrument in the future at an agreed upon price. For example, a futures contract may obligate the Fund, at maturity, to take or make delivery of certain domestic or foreign securities, the cash value of a securities index. When the Fund purchases an option on a futures contract, it has the right to assume a position as a purchaser or seller of a futures contract at a specified exercise price during the option period. When the Fund sells an option on a futures contract, it becomes obligated to purchase or sell a futures contract if the option is exercised.

Futures contracts and options present the following risks: imperfect correlation between the change in market value of the Fund’s securities and the price of futures contracts and options; the possible inability to close a futures contract when desired; losses due to unanticipated market

movements which potentially are unlimited; and the possible inability of the Investment Adviser to correctly predict the direction of securities prices, interest rates, and other economic factors. Futures markets are highly volatile and the use of futures may increase the volatility of the Fund’s NAV. As a result of the low margin deposits normally required in futures trading, a relatively small price movement in a futures contract may result in substantial losses to the Fund. Futures contracts and options on futures may be illiquid, and exchanges may limit fluctuations in futures contract prices during a single day. Foreign exchanges or boards of trade generally do not offer the same protections as U.S. exchanges.

Swaps. Swap agreements may be structured in different ways. Swaps allow a fund to invest in a market without owning or taking physical custody of securities in circumstances in which direct investment is restricted for legal reasons or is otherwise impracticable. Total rate of return swaps are contracts that obligate a party to pay or receive interest in exchange for the payment by the other party of the total return generated by a security, a basket of securities, an index or an index component. Interest rate swaps involve the exchange by the Fund with another party of their respective commitments to pay or receive interest, e.g., an exchange of floating rate payments for fixed rate payments with respect to a notional amount of principal. The use of swaps is a highly specialized activity that involves investment techniques and risks different from those associated with ordinary portfolio securities transactions. Like other derivative instruments, swaps can be highly volatile. If the Investment Adviser is incorrect in its forecasts of market values, the investment performance of the Fund would be less favorable than it would have been if these instruments were not used. Because these instruments normally are illiquid, the Fund may not be able to terminate its obligations when desired. In addition, if the Fund is obligated to pay the return under the terms of a total rate of return swap, Fund losses due to unanticipated market movements potentially are unlimited. The Fund also may suffer a loss if the other party to a transaction defaults.

Options. Options contracts may relate to particular securities, domestic stock indexes, financial instruments or the yield differential between two securities (“yield curve

Additional Fund Information (cont.)

options”) and may or may not be listed on a domestic securities exchange or issued by the Options Clearing Corporation. The Fund may “cover” a call option by owning the security underlying the option or through other means. Put options written by the Fund are “secured” if the Fund maintains liquid assets in a segregated account in an amount at least equal to the exercise price of the option up until the expiration date.

An option is a type of derivative instrument that gives the holder the right (but not the obligation) to buy (a “call”) or sell (a “put”) on an asset in the future at an agreed upon price prior to the expiration date of the option. Options trading is a highly specialized activity that involves investment techniques and risks different from those associated with ordinary Fund securities transactions. The value of options can be highly volatile, and their use can result in loss if the investment management team is incorrect in its expectation of price fluctuations. A Fund will invest and trade in unlisted over-the-counter options only with firms deemed creditworthy by the Investment Adviser. However, unlisted options are not subject to the protections afforded purchasers of listed options by the Options Clearing Corporation, which performs the obligations of its members which fail to perform them in connection with the purchase or sale of options.

•Financial Sector Risk. Companies in the U.S. and non-U.S. financials sector of the economy, including those in the banking industry, are often subject to extensive governmental regulation and intervention, which may adversely affect the scope of their activities, the prices they can charge and the amount of capital they must maintain. Governmental regulation may change frequently and may have significant adverse consequences for companies in the financial sector, including effects not intended by such regulation. The impact of recent or future regulation on any individual financial company, the banking industry or on the sector as a whole cannot be predicted. Certain risks may impact the value of investments in the financial sector more severely than those of investments outside this sector, including

the risks associated with companies that operate with substantial financial leverage. Companies in the financial sector may also be adversely affected by increases in interest rates and loan losses, decreases in the availability of money or asset valuations, credit rating downgrades and adverse conditions in other related markets. Insurance companies, in particular, may be subject to severe price competition and/or rate regulation, which may have an adverse impact on their profitability.

In the recent past, deterioration of the credit markets impacted a broad range of mortgage, asset backed, auction rate, sovereign debt and other markets, including U.S. and non-U.S. credit and interbank money markets, thereby affecting a wide range of financial institutions and markets. A number of large financial institutions have failed, have merged with stronger institutions or have had significant government infusions of capital. Instability in the financial markets has caused certain financial companies to incur large losses. Some financial companies experienced declines in the valuations of their assets, took actions to raise capital (such as the issuance of debt or equity securities), or even ceased operations. Some financial companies borrowed significant amounts of capital from government sources and may face future government-imposed restrictions on their businesses or increased government intervention. Those actions caused the securities of many financial companies to decline in value. The financial sector is particularly sensitive to fluctuations in interest rates.

Foreign Securities Risk. Foreign securities fluctuate in price because of political, financial, social, environmental and economic events in foreign countries (including, for example, military confrontations, war and terrorism). In addition, foreign securities may lose value and a Fund may be adversely impacted by restrictions placed on U.S. investors by U.S. regulations governing foreign investments. A foreign security could also lose value because of more or less stringent foreign securities regulations and less stringent accounting and disclosure standards. In addition, foreign markets may have greater volatility than domestic markets and foreign securities may be less liquid and harder to value than domestic securities.

Additional Fund Information (cont.)

Foreign securities, and in particular foreign debt securities, are sensitive to changes in interest rates. In addition, investment in the securities of foreign governments involves certain additional risks, including the risk that foreign governments may default on their obligations, may not respect the integrity of such debt, may attempt to renegotiate the debt at a lower rate, and may not honor investments by U.S. entities or citizens. The performance of investments in securities denominated in a foreign currency also will depend, in part, on the strength of the foreign currency against the U.S. dollar and the interest rate environment in the country issuing the currency. Absent other events that otherwise could affect the value of a foreign security (such as a change in the political climate or an issuer’s credit quality), appreciation in the value of the foreign currency generally results in an increase in value of a foreign currency-denominated security in terms of U.S. dollars. A decline in the value of the foreign currency relative to the U.S. dollar generally results in a decrease in value of a foreign currency-denominated security. Additionally, many countries throughout the world are dependent on a healthy U.S. economy and are adversely affected when the U.S. economy weakens or its markets decline. For example, the decline in the U.S. subprime mortgage market quickly spread throughout global credit markets, triggering a liquidity crisis that affected fixed-income and equity markets around the world.

Investment in foreign securities may involve higher costs than investment in U.S. securities, including higher transaction and custody costs as well as the imposition of additional taxes by foreign governments. Foreign investments also may involve risks associated with the level of currency exchange rates, less complete financial information about the issuers, less market liquidity and more market volatility and political instability. Future political and economic developments, the possible imposition of withholding taxes on dividend income, the possible seizure or nationalization of foreign holdings, the possible establishment of exchange controls or freezes on the convertibility of currency, trade restrictions (including tariffs) or the adoption of other governmental restrictions might adversely affect an investment in foreign securities. Additionally, foreign banks and foreign branches of domestic banks may be subject to less

stringent reserve requirements and to different accounting, auditing and recordkeeping requirements.

To the extent that the underlying securities and/or other assets held by the Fund trade on foreign exchanges or in foreign markets that may be closed when the securities exchange on which the Fund’s shares trade is open, there are likely to be deviations between the current price of an underlying security and the last quoted price for the underlying security (i.e., the Fund’s quote from the closed foreign market). The impact of a closed foreign market on the Fund is likely to be greater where a large portion of the Fund’s underlying securities and/or other assets trade on that closed foreign market or when the foreign market is closed for unscheduled reasons. These deviations could result in premiums or discounts to the Fund’s NAV that may be greater than those experienced by other ETFs.

Emerging Markets Risk. The risks of foreign investment are increased when the issuer is located in a country with an emerging economy or securities market. Political and economic structures in many of these countries may be undergoing significant evolution and rapid development, and these countries may lack the social, political and economic stability, and impose more governmental limitations on foreign investments, than more developed countries. The securities laws of emerging market countries may be relatively new and unsettled and, consequently, there is a risk of rapid and unpredictable change in laws regarding foreign investment, securities regulation, title to securities and shareholder rights. Global factors and foreign actions may inhibit the flow of foreign capital on which a country is dependent to sustain its growth. In general, securities markets of emerging countries are less liquid, are especially subject to greater price volatility, have smaller market capitalizations, and have problems with securities registration and custody. These securities markets also have less government regulation and are not subject to as stringent regulatory, disclosures, accounting, auditing, recordkeeping, financial and other reporting requirements as the securities markets of more developed countries. In addition, because the securities settlement procedures are less developed in these countries, the Fund may be required to deliver securities before receiving payment and also may be unable to complete transactions during market disruptions. As a result of these the Fund’s purchase and sale of portfolio

Additional Fund Information (cont.)

securities in certain emerging countries may be constrained by limitations relating to daily changes in the prices of listed securities, periodic trading or settlement volume and/or limitations on aggregate holdings of foreign investors. Such limitations may be computed based on the aggregate trading volume by or holdings of the Fund, the Investment Adviser, its affiliates and their respective clients and other service providers. The Fund may not be able to sell securities in circumstances where price, trading or settlement volume limitations have been reached.

Foreign investment in the securities markets of certain emerging countries is restricted or controlled to varying degrees which may limit investment in such countries or increase the administrative costs of such investments. For example, certain Asian countries require governmental approval prior to investments by foreign persons or limit investment by foreign persons to only a specified percentage of an issuer’s outstanding securities or a specific class of securities which may have less advantageous terms (including price) than securities of the issuer available for purchase by nationals. In addition, certain countries may restrict or prohibit investment opportunities in issuers or industries deemed important to national interests. Such restrictions may affect the market price, liquidity and rights of securities that may be purchased by the Fund. The repatriation of both investment income and capital from certain emerging countries is subject to restrictions such as the need for governmental consents.

Many emerging countries have recently experienced currency devaluations and substantial (and, in some cases, extremely high) rates of inflation. Other emerging countries have experienced economic recessions. These circumstances have had a negative effect on the economies and securities markets of those emerging countries. Economies in emerging countries generally are dependent heavily upon commodity prices and international trade and, accordingly, have been and may continue to be affected adversely by the economies of their trading partners, trade barriers, exchange controls, managed adjustments in relative currency values and other protectionist measures imposed or negotiated by the countries with which they trade. Many emerging countries are subject to a substantial degree of economic, political and social instability. Governments of some emerging countries are authoritarian in

nature or have been installed or removed as a result of military coups, while governments in other emerging countries have periodically used force to suppress civil dissent. Disparities of wealth, the pace and success of democratization, and ethnic, religious and racial disaffection, among other factors, have also led to social unrest, violence and/or labor unrest in some emerging countries. Unanticipated political or social developments may result in sudden and significant investment losses. Investing in emerging countries involves greater risk of loss due to expropriation, nationalization, confiscation of assets and property or the imposition of restrictions on foreign investments and on repatriation of capital invested. As an example, in the past some Eastern European governments have expropriated substantial amounts of private property, and many claims of the property owners have never been fully settled. There is no assurance that similar expropriations will not recur in Eastern European or other countries. Emerging markets countries also may have less developed legal systems allowing for enforcement of private property rights and/or redress for injuries to private property, such as bankruptcy. The ability to bring and enforce actions in emerging market countries, or to obtain information needed to pursue or enforce such actions, may be limited and shareholder claims may be difficult or impossible to pursue.

The Fund’s investment in emerging countries may also be subject to withholding or other taxes, which may be significant and may reduce the return from an investment in such countries to the Fund.

Settlement and clearance procedures in emerging countries are frequently less developed and reliable than those in the United States and may involve the Fund’s delivery of securities before receipt of payment for their sale. In addition, significant delays may occur in certain markets in registering the transfer of securities. Settlement, clearance or registration problems may make it more difficult for the Fund to value its portfolio securities and could cause the Fund to miss attractive investment opportunities, to have a portion of its assets uninvested or to incur losses due to the failure of a counterparty to pay for securities the Fund has delivered or the Fund’s inability to complete its contractual obligations because of theft or other reasons. In addition, local agents and depositories are subject to local standards of care that may not be as rigorous as developed countries.

Additional Fund Information (cont.)

Governments and other groups may also require local agents to hold securities in depositories that are not subject to independent verification. The less developed a country’s securities market, the greater the risk to the Fund.

The creditworthiness of the local securities firms used by the Fund in emerging countries may not be as sound as the creditworthiness of firms used in more developed countries. As a result, the Fund may be subject to a greater risk of loss if a securities firm defaults in the performance of its responsibilities.

The small size and inexperience of the securities markets in certain emerging countries and the limited volume of trading in securities in those countries may make the Fund’s investments in such countries less liquid and more volatile than investments in countries with more developed securities markets (such as the United States, Japan and most Western European countries). The Fund’s investments in emerging countries are subject to the risk that the liquidity of a particular investment, or investments generally, in such countries will shrink or disappear suddenly and without warning as a result of adverse economic, market or political conditions or adverse investor perceptions, whether or not accurate. Because of the lack of sufficient market liquidity, the Fund may incur losses because it will be required to effect sales at a disadvantageous time and then only at a substantial drop in price. Investments in emerging countries may be more difficult to price precisely because of the characteristics discussed above and lower trading volumes.

The Fund’s use of foreign currency management techniques in emerging countries may be limited. Due to the limited market for these instruments in emerging countries, all or a significant portion of the Fund’s currency exposure in emerging countries may not be covered by such instruments.

From time to time, certain of the companies in which the Fund may invest may operate in, or have dealings with, countries subject to sanctions or embargoes imposed by the U.S. government and the United Nations and/or countries identified by the U.S. government as state sponsors of terrorism. A company may suffer damage to its reputation if it is identified as a company which operates in, or has dealings with, countries subject to sanctions or embargoes

imposed by the U.S. government and the United Nations and/or countries identified by the U.S. government as state sponsors of terrorism. As an investor in such companies, the Fund will be indirectly subject to those risks.

Russia’s military invasion of Ukraine in February 2022, the resulting responses by the United States and other countries, and the potential for wider conflict could increase volatility and uncertainty in the financial markets and adversely affect regional and global economies. The United States and other countries have imposed broad ranging economic sanctions on Russia and certain Russian individuals, banking entities and corporations as a response to Russia’s invasion of Ukraine. The United States and other countries have also imposed economic sanctions on Belarus and may impose sanctions on other countries that support Russia’s military invasion. These sanctions, as well as any other economic consequences related to the invasion or cyberattacks on governments, companies or individuals, have already decreased, and may further decrease, the value and liquidity of certain Russian securities and securities of issuers in other countries that are subject to economic sanctions related to the invasion. To the extent that a Fund has exposure to Russian or other Eastern European investments, the Fund’s ability to price, buy, sell, receive or deliver such investments may be impaired. These and any related events could significantly impact a Fund’s performance and the value of an investment in the Fund, even beyond any direct exposure the Fund may have to Russian issuers or adjoining geographic regions.

Geographic Risk. If a fund invests a significant portion of its total assets in certain issuers within the same country or geographic region, an economic, business or political development affecting that country or region may affect the value of the fund’s investments more than if the fund’s investments were not so concentrated in such country or region.

Hedging Risk. While hedging can reduce or eliminate losses, it can also reduce or eliminate gains. Hedges are sometimes subject to imperfect matching between the derivative and the underlying security, and there can be no assurance that a Fund’s hedging transactions, which entail additional transaction costs, will be effective.

Additional Fund Information (cont.)

Short positions in U.S. Treasury futures and similar positions through transactions in interest rate swaps are not intended to mitigate credit spread risk or other factors influencing the price of bonds, which may have a greater impact than interest rates. There is no guarantee that the Fund’s short positions will completely eliminate the interest rate risk of the long positions in bonds. In addition, when interest rates fall, long-only bond investments will perform better than the Fund’s investments. In certain falling interest rate environments, the Fund’s hedging strategy could result in disproportionately larger losses in the short U.S. Treasury futures and interest rate swaps positions as compared to gains in the long bond positions attributable to interest rate changes. There is no guarantee the Fund will have positive returns, even in environments of sharply rising Treasury interest rates in which the Fund’s short positions might be expected to mitigate the effects of such rises. The Fund will incur expenses when entering into short positions. The use of hedging may result in certain adverse tax consequences.

Income Risk. A Fund’s income may decline when interest rates fall. This decline can occur because a Fund must invest in lower-yielding bonds as bonds in its portfolio mature or a Fund otherwise needs to purchase additional bonds. In the case of the FlexShares® Core Select Bond Fund, this decline can also occur because the bonds in an Underlying Fund’s underlying index are substituted or the Underlying Fund otherwise needs to purchase additional bonds. An index provider’s substitution of bonds in an Underlying Fund’s underlying index may occur, for example, when the time to maturity for the bond no longer matches the underlying index’s stated maturity guidelines.

Interest Rate/Maturity Risk. Generally, when interest rates rise, prices of fixed-income securities fall. However, market factors, such as the demand for particular fixed-income securities, may cause the price of certain fixed-income securities to fall while the prices of other securities rise or remain unchanged. A fixed-income security’s duration approximates its price sensitivity to changes in interest rates. For example, suppose that interest rates in one day fall by one percent which, in turn, causes yields on every bond in the market to fall by the same amount. In this example, the price of a bond with a duration of three years may be expected to rise approximately three percent and

the price of a bond with a five year duration may be expected to rise approximately five percent. The converse is also true. Suppose interest rates in one day rise by one percent which, in turn, causes yields on every bond in the market to rise by the same amount. In this second example, the price of a bond with a duration of three years may be expected to fall approximately three percent and the price of a bond with a five year duration may be expected to fall approximately five percent. Interest rate changes have a greater effect on the price of fixed-income securities with longer durations. Certain factors, such as the presence of call features, may cause a particular fixed-income security, or a Fund as a whole, to exhibit less sensitivity to changes in interest rates. The maturity of a security, another commonly used measure of price sensitivity, measures only the time until final payment is due, whereas duration takes into account the pattern of all payments of interest and principal on a security over time, including how these payments are affected by prepayments and by changes in interest rates, as well as the time until an interest rate on a security is reset (in the case of variable-rate securities).

The maturities of certain instruments, such as variable and floating rate instruments, are subject to estimation. In addition, in calculating average weighted maturities, the maturity of mortgage and other asset-backed securities will be based on estimates of average life. As a result, a Fund cannot guarantee that these estimates will, in fact, be accurate or that its average maturity will remain within the specified limit.

A wide variety of factors can cause interest rates to rise (e.g., central bank monetary policies, inflation rates, general economic conditions, etc.). An increase in interest rates may lead to heightened volatility in the fixed-income markets and may adversely affect the liquidity of certain fixed-income investments.

Leveraging Risk. Certain transactions may give rise to a form of leverage. Such transactions may include, among others, reverse repurchase agreements, leveraged inverse floating rate instruments, mortgage dollars rolls and the use of when-issued, delayed delivery or forward commitment transactions. The Fund also may be exposed to leveraging risk by borrowing money for investment purposes.

Additional Fund Information (cont.)

Leveraging may cause the Fund to liquidate portfolio positions to satisfy its obligations. Leveraging, including borrowing, may cause the Fund to be more volatile than if the Fund had not been leveraged. Relatively small market movements may result in large changes in the value of a leveraged investment. This is because leveraging tends to exaggerate the effect of any increase or decrease in the value of the Fund’s portfolio securities.

Liquidity Risk. To the extent a Fund invests in illiquid investments or investments that become illiquid, such investments may have a negative effect on the returns of the Fund because the Fund may be unable to sell the illiquid investments at an advantageous time or price. Liquid investments may become illiquid after purchase by a Fund, particularly during periods of market turmoil. Illiquid investments may be harder to value, especially in changing markets, and if a Fund is forced to sell these investments to meet redemption requests or for other cash needs, the Fund may suffer a loss.

Liquidity risk may result from the lack of an active market, reduced number and capacity of traditional market participants to make a market in fixed income securities, and may be magnified in a rising interest rate environment or other circumstances where investor redemptions from fixed income funds may be higher than normal, causing increased supply in the market due to selling activity.

Additionally, the market for certain investments may become illiquid under adverse market or economic conditions independent of any specific adverse changes in the conditions of a particular issuer. In adverse market conditions, a Fund’s market price may begin to reflect illiquidity or pricing uncertainty of the Fund’s portfolio securities. This could lead to a Fund’s shares trading at a price that is higher or lower than the Fund’s NAV. At times, such differences may be significant.

Management Risk. The Investment Adviser will make investment decisions for each Fund, but there can be no guarantee that these decisions will produce the intended results. In addition, legislative, regulatory, or tax developments may affect the investment techniques available to the Investment Adviser to manage a Fund and may also adversely affect the ability of a Fund to achieve its investment objective.

Market Risk. The value of a Fund’s investments may increase or decrease in response to expected real or perceived economic, political or financial events in the U.S. or global markets. The frequency and magnitude of such changes in value cannot be predicted. Certain securities and other investments held by a Fund may experience increased volatility, illiquidity, or other potentially adverse effects in response to changing market conditions, inflation, changes in interest rates, lack of liquidity in the bond or equity markets, volatility in the equities market or adverse investor sentiment. Local, regional or global events such as war, acts of terrorism, the spread of infectious illness or other public health issues, recessions, or other events or adverse investor sentiment or other political, regulatory, economic and social developments, and developments that impact specific economic sectors, industries or segments of the market or other events could have a significant impact on a Fund and its investments and could result in a Fund’s shares trading at increased premiums or discounts to the Fund’s NAV. These risks may be magnified if certain events or developments adversely interrupt the global supply chain. Market risk includes the risk that a particular style of investing, such as growth or value, may underperform the market generally. The value of the securities in which a Fund invests may go up or down in response to the prospects of individual issuers and/or general economic conditions. Securities markets may experience great short-term volatility and may fall sharply at times. Different markets may behave differently from each other and a foreign market may move in the opposite direction from the U.S. market. Price changes may be temporary or last for extended periods. You could lose money over short periods due to fluctuation in the market prices of a Fund’s shares in response to market movements, and over longer periods during market downturns.

Periods of unusually high financial market volatility and restrictive credit conditions, at times limited to a particular sector or geographic area, have occurred in the past and may be expected to recur in the future. Some countries, including the United States, have adopted or have signaled protectionist trade measures, relaxation of the financial industry regulations that followed the financial crisis, and/or reductions to corporate taxes. The scope of these policy changes is still developing, but the equity and debt

Additional Fund Information (cont.)

markets may react strongly to expectations of change, which could increase volatility, particularly if a resulting policy runs counter to the market’s expectations. The outcome of such changes cannot be foreseen at the present time. In addition, geopolitical and other risks, including environmental and public health risks, may add to instability in the world economy and markets generally. As a result of increasingly interconnected global economies and financial markets, the value and liquidity of a Fund’s investments may be negatively affected by events impacting a country or region, regardless of whether the Fund invests in issuers located in or with significant exposure to such country or region.

An outbreak of respiratory disease caused by a novel coronavirus was first detected in December 2019 and has spread internationally. The outbreak and efforts to contain its spread have at times resulted in closing borders and quarantines, restricting international and domestic travel, enhanced health screenings, cancellations, disrupted supply chains and customer activity, responses by businesses (including changes to operations and reducing staff), and have produced general concern and uncertainty. The impact of the coronavirus pandemic, and other epidemics and pandemics that may arise in the future, could adversely affect national and global economies, individual companies and the market in general in a manner and for a period of time that cannot be foreseen at the present time. Health crises caused by the recent outbreak may heighten other preexisting political, social and economic risks in a country or region. Governmental authorities and regulators throughout the world, such as the U.S. Federal Reserve, have in the past responded to major economic disruptions with changes to fiscal and monetary policy, including but not limited to, direct capital infusions, new monetary programs, and dramatically lower interest rates. Certain of those policy changes are being implemented or considered in response to the coronavirus outbreak. Such policy changes may adversely affect the value, volatility and liquidity of dividend and interest paying securities. In certain cases, an exchange or market may close or issue trading halts on either specific securities or even the entire market, which may result in a Fund being, among other things, unable to buy or sell certain securities or financial instruments or to accurately price its investments. In the

event of a pandemic or an outbreak, there can be no assurance that the Funds and their service providers will be able to maintain normal business operations for an extended period of time or will not lose the services of key personnel on a temporary or long-term basis due to illness or other reasons. A pandemic or disease could also impair the information technology and other operational systems upon which the Investment Adviser relies, and could otherwise disrupt the ability of the Fund’s service providers to perform essential tasks. Although multiple asset classes may be affected by a market disruption, the duration and effects may not be the same for all types of assets. To the extent a Fund may overweight its investments in certain countries, companies, industries or market sectors, such position will increase the Fund’s exposure to risk of loss from adverse developments affecting those countries, companies, industries or sectors. These conditions could result in a Fund’s inability to achieve its investment objectives, adversely affect the prices and liquidity of the securities and other instruments in which a Fund invests, negatively impact a Fund’s performance, and cause losses on your investment in a Fund. During periods of market disruption or other abnormal market conditions, a Fund’s exposure to the risks described elsewhere in this Prospectus will likely increase. You should also review this prospectus and the SAI to understand each Fund’s discretion to implement temporary defensive measures.

Market Trading Risks

Absence of Active Market

Although the shares of the Funds described in this Prospectus are listed for trading on a listing exchange and may be listed on certain foreign exchanges, there can be no assurance that an active trading market for such shares will be maintained.

Lack of Market Liquidity

Secondary market trading in Fund shares may be halted by a listing exchange because of market conditions or for other reasons. In addition, trading in Fund shares is subject to trading halts caused by extraordinary market volatility pursuant to “circuit breaker” rules. There can be no assurance that the requirements necessary to maintain the listing of the shares of a Fund will continue to be met or will remain unchanged.

Additional Fund Information (cont.)

Shares of the Fund May Trade at Prices Other Than NAV

Shares of the Funds may trade at, above or below their most recent NAV. The per share NAV of each Fund is calculated at the end of each business day and fluctuates with changes in the market value of such Fund’s holdings since the prior most recent calculation. The trading prices of a Fund’s shares will generally fluctuate in accordance with changes in its NAV, changes in the relative supply of, and demand for, Fund shares, and changes in the liquidity, or the perceived liquidity, of the Fund’s holdings. The trading prices of a Fund’s shares may deviate significantly from NAV during periods of market volatility. These factors, among others, may lead to a Fund’s shares trading at a premium or discount to NAV. While the creation/redemption feature is designed to make it likely that a Fund’s shares normally will trade close to the Fund’s NAV, exchange prices are not expected to correlate exactly with a Fund’s NAV due to timing reasons as well as market supply and demand factors. In addition, disruptions to creations and redemptions including disruptions at market makers, Authorized Participants, or market participants or during periods of significant volatility, may result in trading prices that differ significantly from NAV. For example, during a “flash crash,” the market prices of a Fund's shares may decline suddenly and significantly. Such a decline may not reflect the performance of the portfolio securities held by the Fund. Flash crashes may cause Authorized Participants and other market makers to limit or cease trading in Fund shares for temporary or longer periods. Shareholders could suffer significant losses to the extent that they sell Fund shares at these temporarily low market prices. If a shareholder purchases at a time when the market price of a Fund is at a premium to its NAV or sells at time when the market price is at a discount to the NAV, the shareholder may sustain losses that are in addition to any losses caused by a decrease in NAV.

Since foreign exchanges may be open on days when a Fund does not price its shares, the value of the securities in the Fund’s portfolio may change on days when shareholders will not be able to purchase or sell the Fund’s shares.

Secondary Market Trading Risk

A Fund may experience low trading volume and wide bid/ask spreads. Bid/ask spreads vary over time based on trading volume and market liquidity (including for the underlying securities held by the Fund), and are generally lower if shares of a Fund have more trading volume and market liquidity and higher if shares of the Fund have little trading volume and market liquidity. In stressed market conditions, the market for a Fund’s shares may become less liquid in response to declining liquidity in the markets for the Fund’s portfolio holdings, which may cause a variance in the market price of the Fund’s shares and their underlying value.

Municipal Market Volatility Risk. Municipal instruments include debt obligations issued by or on behalf of states, territories and possessions of the United States and their political subdivisions, agencies, authorities and instrumentalities. The FlexShares® Core Select Bond Fund may invest in Underlying Funds that invest in obligations of state and local governments.

The risk of a municipal obligation generally depends on the financial and credit status of the issuer. Changes in a municipality’s financial health may make it difficult for the municipality to make interest and principal payments when due. This could decrease a Fund’s investment performance and liquidity. Under some circumstances, municipal obligations might not pay interest unless the state legislature or municipality authorizes money for that purpose.

Municipal instruments include both “general” and “revenue” bonds and may be issued to obtain funds for various public purposes. General obligations are secured by the issuer’s pledge of its full faith, credit and taxing power. Revenue obligations are payable only from the revenues derived from a particular facility or class of facilities. In some cases, revenue bonds also are payable from the proceeds of a special excise or other specific revenue source such as lease payments from the user of a facility being financed.

Some municipal instruments, known as private activity bonds, are issued to finance projects for private companies. Private activity bonds are usually revenue obligations since they typically are payable by the private user of the facilities financed by the bonds.

Additional Fund Information (cont.)

Municipal instruments also include “moral obligation” bonds, municipal leases, certificates of participation and asset-backed securities such as custodial receipts. Moral obligation bonds are supported by a moral commitment but not a legal obligation of a state or municipality. Municipal leases and participation certificates present the risk that the state or municipality involved will not appropriate the monies to meet scheduled payments on an annual basis. Custodial receipts represent interests in municipal instruments held by a trustee or custodian.

Municipal instruments also include tax-exempt derivative instruments that have interest rates that reset inversely to changing short-term rates and/or have imbedded interest rate floors and caps that require the issuer to pay an adjusted interest rate if market rates fall below or rise above a specified rate.

The Fund may acquire “stand-by commitments” relating to the municipal instruments it holds. Under a stand-by commitment, a dealer agrees to purchase, at the Fund’s option, specified municipal instruments at a specified price. A stand-by commitment may increase the cost, and thereby reduce the yield, of the municipal instruments to which the commitment relates. The Fund will acquire stand-by commitments solely to facilitate portfolio liquidity and does not intend to exercise its rights for trading purposes.

Municipal instruments may be backed by letters of credit, insurance or other forms of credit enhancement issued by foreign and domestic banks, insurance companies and other financial institutions. If the credit quality of these banks, insurance companies and financial institutions declines, the Fund could suffer a loss to the extent that the Fund is relying upon this credit support. Foreign institutions can present special risks relating to higher transaction and custody costs, the imposition of additional taxes by foreign governments, less complete financial information, less market liquidity, more market volatility and political instability. Foreign banks, insurance companies and financial institutions may be subject to less stringent reserve requirements, and to different accounting, auditing and recordkeeping requirements than U.S. banks.

In addition, a single enhancement provider may provide credit enhancement to more than one of the Fund’s investments. Having multiple securities credit enhanced by the

same enhancement provider will increase the adverse effects on the Fund that are likely to result from a downgrading of, or a default by, such an enhancement provider. Adverse developments in the banking or bond insurance industries also may negatively affect the Fund. Bond insurers that provide credit enhancement for large segments of the fixed-income markets, particularly the municipal bond market, may be more susceptible to being downgraded or defaulting during recessions or similar periods of economic stress. Municipal bonds may be covered by insurance that guarantees timely interest payments and repayment of principal on maturity. If a bond’s insurer fails to fulfill its obligations or loses its credit rating, the value of the bond could drop. Insurance does not protect the Fund or its shareholders from losses caused by declines in a bond’s market value.

Also, an insurance company’s exposure to securities involving subprime mortgages may cause a municipal bond insurer’s rating to be downgraded or may cause the bond insurer to become insolvent, which may affect the prices and liquidity of municipal obligations insured by the insurance company. In addition, if a substantial portion of the Fund’s assets are invested in instruments that are used to finance facilities involving a particular industry, whose issuers are in the same state or which otherwise are related, there is a possibility that an economic, business or political development affecting one instrument would likewise affect the related instrument.

Additionally, the increased presence of nontraditional participants (such as proprietary trading desks of investment banks and hedge funds) or the absence of traditional participants (such as individuals, insurance companies, banks and life insurance companies) in the municipal markets may lead to greater volatility in the markets because non-traditional participants may trade more frequently or in greater volume. In recent years, an increasing number of municipal issuers have defaulted on obligations, been downgraded or commenced insolvency proceedings. Municipalities continue to experience difficulties in the current economic and political environment.

Prepayment (or Call) Risk. The issuer of a security held by a Fund (such as a mortgage-related or other asset-backed security) may under certain circumstances make principal

Additional Fund Information (cont.)

payments on such security sooner than expected. This may occur, for example, when interest rates decline. Such sooner-than-expected principal payments may reduce the returns of a Fund because a Fund is forced to forego expected future interest payments on the principal amount paid back early and a Fund may be forced to reinvest the money it receives from such early payments at the lower prevailing interest rates.

Securities Lending Risk. In order to generate additional income, the Funds may lend securities to banks, brokers and dealers or other qualified institutions. In exchange, a Fund will receive collateral equal to at least 100% of the value of the securities loaned.

Securities lending may represent no more than one-third of the value of a Fund’s total assets (including the loan collateral). Any cash collateral received by a Fund in connection with these loans may be invested in a variety of short-term investments, either directly or indirectly through money market portfolios. Loan collateral (including any investment of the collateral) is not included in the calculation of the percentage limitations described elsewhere in this Prospectus regarding a Fund’s investments in particular types of securities.

A principal risk when lending portfolio securities is that the borrower might become insolvent or refuse to honor its obligation to return the securities. In this event, a Fund could experience delays in recovering its securities and possibly may incur a capital loss. A Fund will be responsible for any loss that might result from its investment of the cash collateral it receives from a borrower. Additionally, the amount of a Fund’s distributions that qualify for taxation at reduced long-term capital gains rates for individuals, as well as the amount of a Fund’s distributions that qualify for the dividends received deduction available to corporate shareholders (together, “qualifying dividends”) may be reduced as a result of a Fund’s securities lending activities. This is because any dividends paid on securities while on loan will not be deemed to have been received by a Fund, and the equivalent amount paid to a Fund by the borrower of the securities will not be deemed to be a qualifying dividend.

Underlying Fund Risk. The FlexShares® Core Select Bond Fund’s investments may be significantly concentrated in its

Underlying Funds, and, as a result, the Fund’s investment performance may be directly related to the investment performance of the Underlying Funds held by it. The ability of the Fund to meet its investment objective may be directly related to the ability of the Underlying Funds to meet their objectives as well as the allocation among those Underlying Funds. The value of the Underlying Funds’ investments, and the NAVs of the shares of both the Fund and the Underlying Funds, will fluctuate in response to various market and economic factors related to the equity and fixed income markets, as well as the financial condition and prospects of issuers in which the Underlying Funds invest. There can be no assurance that the investment objectives of the Underlying Funds will be achieved.

Market Value Risk. The market value of an ETF’s shares may differ from its NAV. This difference in price may be due to the fact that the supply and demand in the market for ETF shares at any point in time is not always identical to the supply and demand in the market for the underlying basket of securities. Accordingly, there may be times when an ETF trades at a premium (creating the risk that the Fund pays more than NAV for an ETF when making a purchase) or discount (creating the risks that the Fund’s NAV is reduced for undervalued ETFs it holds, and that the Fund receives less than NAV when selling an ETF).

Tracking Risk. Index-based ETFs and other investment companies in which the Fund invests may not be able to replicate exactly the performance of the indices they track because the total return generated by the securities will be reduced by transaction costs incurred in adjusting the actual balance of the securities. In addition, index-based ETFs and other investment companies in which the Fund invests may incur expenses not incurred by their applicable indices. Certain securities comprising the indices may, from time to time, temporarily be unavailable, which may further impede an ETF’s or other investment company’s ability to track its applicable index or match its performance.

Passive Investment Risk. An index-based Underlying Fund may be affected by a general decline in the market segments relating to its underlying index. An index-based

Additional Fund Information (cont.)

Underlying Fund invests in securities included in, or representative of, its underlying index regardless of their investment merit. The investment adviser of an index-based Underlying Fund does not attempt to take defensive positions in any market conditions, including declining markets.

Sampling Risk. The index-based ETFs in which the Fund invests may utilize a representative sampling approach to track their respective underlying indices. ETFs that utilize a representative sampling approach are subject to an increased risk of tracking error because the securities selected for the ETF in the aggregate may vary from the investment profile of the underlying index. Additionally, if using a representative sampling approach, an ETF will typically hold a smaller number of securities than the underlying index, and as a result, an adverse development to an issuer of securities that the ETF holds could result in a greater decline in NAV than would be the case if the ETF held all of the securities in the underlying index.

Expenses. To the extent the Fund invests in Underlying Funds, your cost of investing in the Fund will generally be higher than the cost of investing directly in Underlying Funds, because you will indirectly bear fees and expenses charged by the Underlying Funds in which the Fund invests in addition to the Fund’s direct fees and expenses. Furthermore, Fund investments in Underlying Funds could affect the timing, amount, and character of the Fund’s distributions and therefore may increase the amount of your tax liability.

U.S. Government Securities Risk. U.S. Government Securities include U.S. Treasury obligations, such as bills, notes and bonds, which generally differ only in terms of their interest rates, maturities and time of issuance. They also include obligations issued or guaranteed by the U.S. government or by its agencies, instrumentalities or sponsored enterprises. Securities guaranteed as to principal and interest by the U.S. government or by its agencies, instrumentalities or sponsored enterprises are deemed to include (a) securities for which the payment of principal and interest is backed by an irrevocable letter of credit issued by the U.S. government or by an agency, instrumentality or sponsored enterprise thereof, (b) securities of private issuers guaranteed as to principal and interest by the U.S. government, its

agencies and instrumentalities and (c) participations in loans made to foreign governments or their agencies that are so guaranteed.

Not all U.S. government obligations carry the same credit support. Although many U.S. government securities in which a Fund may invest, such as those issued by the Federal National Mortgage Association (“Fannie Mae”), Federal Home Loan Mortgage Corporation (“Freddie Mac”) and Federal Home Loan Banks may be chartered or sponsored by Acts of Congress, their securities are neither issued nor guaranteed by the U.S. Treasury and, therefore, are not backed by the full faith and credit of the United States. Some, such as those of the Government National Mortgage Association (“Ginnie Mae”), are supported by the full faith and credit of the U.S. Treasury. Other obligations, such as those of the Federal Home Loan Banks, are supported by the right of the issuer to borrow from the U.S. Treasury; and others are supported by the discretionary authority of the U.S. government to purchase the agency’s obligations. Still others are supported only by the credit of the instrumentality or sponsored enterprise. The maximum potential liability of the issuers of some U.S. government securities held by a Fund may greatly exceed their current resources, including their legal right to support from the U.S. Treasury. It is possible that these issuers will not have the funds to meet their payment obligations in the future. No assurance can be given that the U.S. government would provide financial support to its agencies, instrumentalities or sponsored enterprises if it is not obligated to do so by law. In addition, the secondary market for certain participations in loans made to foreign governments or their agencies may be limited.

An agency of the U.S. government has placed Fannie Mae and Freddie Mac into conservatorship, a statutory process with the objective of returning the entities to normal business operations. It is unclear what effect this conservatorship will have on the securities issued or guaranteed by Fannie Mae or Freddie Mac. As a result, these securities are subject to more credit risk than U.S. government securities that are supported by the full faith and credit of the United States (e.g., U.S. Treasury bonds).

To the extent each Fund invests in debt instruments or securities of non-U.S. government entities that are backed

Additional Fund Information (cont.)

by the full faith and credit of the United States, there is a possibility that such guarantee may be discontinued or modified at a later date.

Valuation Risk. The sale price a Fund could receive for a security may differ from the Fund’s valuation of the security, particularly for securities that trade in low volume or volatile markets, or that are valued using a fair value methodology. Fair valuation of the Fund’s investments involves subjective judgment. Because portfolio securities may be traded on non-U.S. exchanges, and non-U.S. exchanges may be open on days when the Fund does not price its shares, the value of the securities in the Fund’s portfolio may change on days when shareholders will not be able to purchase or sell the Fund’s shares. The Fund relies on various sources to calculate its NAV. The information may be provided by third parties that are believed to be reliable, but the information may not be accurate due to errors by such pricing sources, technological issues or otherwise.

Additional Information About the Funds’ Investments and Other Risks

The principal risks of investing in the Funds are described under each “Fund Summary” above, and in “Additional Information About the Funds’ Principal Risks” above on page 18. This section provides additional information about some of the investments and related risks described under the “Fund Summary” for each Fund above. It also describes additional risks faced by the Funds and investment techniques that may be used by the Fund from time to time. Many of the investment techniques described herein are discretionary, which means the Investment Adviser can decide whether to use them or not. This Prospectus does not attempt to disclose all of the various types of instruments and investment techniques that may be used by the Funds. As with any fund, investors in the Funds rely on the professional investment judgment and skill of the Investment Adviser and the individual portfolio managers. Please see the Statement of Additional Information (“SAI”) for more information about the instruments and investment techniques described in this section and about other instruments and techniques that may be used by the Funds.

The FlexShares® Core Select Bond Fund may be exposed to these risks directly, or indirectly through the Fund’s investments in the Underlying Funds.

Bank Capital Securities and Trust Preferred Securities. There are two common types of bank capital: Tier I and Tier II. Bank capital is generally, but not always, of investment grade quality. Tier I securities often take the form of trust preferred securities. Tier II securities are commonly thought of as hybrids of debt and preferred stock, are often perpetual (with no maturity date), callable and, under certain conditions, allow for the issuer bank to withhold payment of interest until a later date.

Trust preferred securities have the characteristics of both subordinated debt and preferred stock. The primary advantage of the structure of trust preferred securities is that they are treated by the financial institution as debt securities for tax purposes and as equity for the calculation of capital requirements. Trust preferred securities typically bear a market rate coupon comparable to interest rates available on debt of a similarly rated issuer. Typical characteristics include long-term maturities, early redemption by the issuer, periodic fixed or variable interest payments, and maturities at face value. The market value of trust preferred securities may be more volatile than those of conventional debt securities. There can be no assurance as to the liquidity of trust preferred securities and the ability of holders, such as the Funds, to sell their holdings.

Borrowings and Reverse Repurchase Agreements. Each Fund may borrow money and enter into reverse repurchase agreements in amounts not exceeding one-fourth of the value of its total assets (including the amount borrowed). Each Fund may enter into reverse repurchase agreements in amounts not exceeding 20% of the Fund’s total assets. Each Fund may enter into reverse repurchase agreements when the Investment Adviser expects that the interest income to be earned from the investment of the transaction proceeds will be greater than the related interest expense. Reverse repurchase agreements involve the sale of securities held by a Fund subject to the Fund’s agreement to repurchase them at a mutually agreed upon date and price (including interest).

Borrowings and reverse repurchase agreements involve leveraging. If the securities held by a Fund decline in value

Additional Fund Information (cont.)

while these transactions are outstanding, the NAV of the Fund’s outstanding shares will decline in value by proportionately more than the decline in value of the securities. In addition, reverse repurchase agreements involve the risks that (a) the interest income earned by a Fund (from the investment of the proceeds) will be less than the interest expense of the transaction; (b) the market value of the securities sold by the Fund will decline below the price the Fund is obligated to pay to repurchase the securities; and (c) the securities may not be returned to the Fund.

Corporate Debt Securities. Corporate debt securities are subject to the risk of the issuer’s inability to meet principal and interest payments on the obligation and may also be subject to price volatility due to such factors as interest rate sensitivity, market perception of the creditworthiness of the issuer and general market liquidity. When interest rates rise, the value of corporate debt securities can be expected to decline. Debt securities with longer maturities tend to be more sensitive to interest rate movements than those with shorter maturities.

Custodial Receipts. To the extent consistent with its investment objectives and strategies, each Fund may invest a portion of its assets in custodial receipts. Custodial receipts are participations in trusts that hold U.S. government, bank, corporate or other obligations. U.S. Treasury securities are sold under names such as TIGRs (Treasury Income Growth Receipts) and CATS (Certificates of Accrual on Treasury Securities). Like other stripped obligations, they entitle the holder to future interest payments or principal payments or both on securities held by the custodian. Custodial receipts may be subject to greater price volatility than ordinary debt obligations because of the way in which their principal and interest are returned to investors. Custodial receipts may not be considered obligations of the U.S. government or other issuer of the security held by the custodian for the purposes of securities laws. If for tax purposes a Fund is not considered to be the owner of the securities held in the underlying trust or custodial account, the Fund may suffer adverse tax consequences. As a holder of custodial receipts, a Fund will bear its proportionate share of the fees or expenses charged to the custodial account.

Cyber Security and Operational Risk. The Funds and their service providers may experience disruptions that arise

from breaches in cyber security, human error, processing and communications errors, counterparty or third-party errors, technology or systems failures, any of which may have an adverse impact on the Funds. Failures or breaches of the electronic systems of the Funds, the Investment Adviser, distributor, and other service providers, market makers, Authorized Participants (collectively, the “Service Providers”) or the issuers of securities in which the Funds invest have the ability to cause disruptions and negatively impact the Funds’ business operations, potentially resulting in financial losses to the Funds and their shareholders.

With the increased use of the Internet and because information technology (“IT”) systems and digital data underlie most of the Funds’ operations, the Funds and their Service Providers and their vendors are exposed to the risk that their operations and data may be compromised as a result of internal and external cyber-failures, breaches or attacks (“Cyber Risk”). This could occur as a result of malicious or criminal cyber-attacks. Cyber-attacks include actions taken to: (i) steal or corrupt data maintained online or digitally, (ii) gain unauthorized access to or release confidential information, (iii) shut down a Fund or Service Provider website through denial-of-service attacks or (iv) otherwise disrupt normal business operations. However, events arising from human error, faulty or inadequately implemented policies and procedures or other systems failures unrelated to any external cyber-threat may have effects similar to those caused by deliberate cyber-attacks. Among other situations, disruptions (for example, pandemics and health crises) that cause prolonged periods of remote work or significant employee absences at the Funds' service providers could impact the ability to conduct the Funds' operations.

Successful cyber-attacks or other cyber-failures or events affecting the Funds or their Service Providers may adversely impact a Fund or its shareholders or cause an investment in the Fund to lose value. For instance, they may impact a Fund’s ability to calculate its NAV, cause the release of confidential Fund information, impede trading, or cause reputational damage. They could also subject a Fund or its Service Providers to regulatory fines, penalties or financial losses, reimbursement or other compensation costs, and/or additional compliance costs. Insurance protection and contractual indemnification provisions may

Additional Fund Information (cont.)

not be available or may be insufficient to cover these losses. The Funds or their Service Providers may also incur significant costs to manage and control Cyber Risk.

Cyber Risks are also present for issuers of securities or other instruments in which the Funds invest, which could result in material adverse consequences for such issuers, and may cause a Fund’s investment in such issuers to lose value.

While the Investment Adviser, Service Providers or Authorized Participants may have established business continuity plans and risk management systems to prevent such cyber attacks, there are inherent limitations in such plans and systems, including the possibility that certain risks have not been identified or that cyber attacks may be highly sophisticated.

The Funds and their shareholders could be negatively impacted as a result.

Fixed-Income Instruments. The FlexShares® Ultra-Short Income Fund seeks to achieve its investment objective by investing under normal circumstances at least 80% of its total assets in a portfolio of fixed-income instruments, including bonds, debt securities and other similar instruments issued by U.S. and non-U.S. public and private sector entities. “Fixed-income instruments,” as used generally for the Fund, include but are not limited to:

•securities issued or guaranteed by the U.S. Government, its agencies or government sponsored enterprises;

•corporate debt securities of U.S. and non-U.S. issuers, including corporate commercial paper;

•mortgage-backed and other asset-backed securities;

•inflation-indexed bonds issued both by governments and corporations;

•bank capital and trust preferred securities;

•loan participations and assignments;

•bank certificates of deposit, fixed time deposits and bankers’ acceptances;

•debt securities issued by states or local governments and their agencies, authorities and other government sponsored enterprises;

•obligations of non-U.S. governments or their subdivisions, agencies and government-sponsored enterprises; and

•obligations of international agencies or supranational entities.

The FlexShares® Core Select Bond Fund seeks to achieve its investment objective by investing under normal circumstances at least 80% of its net assets in U.S. dollar denominated investment-grade fixed-income securities, including bonds, debt securities and other similar instruments issued by U.S. public and U.S. and non-U.S. private sector entities.

Fixed income instruments, including corporate debt obligations, generally expose the Funds to the following types of risk: (1) interest rate risk (the potential for fluctuations in bond prices due to changing interest rates); (2) income risk (the potential for a decline in the Funds’ income due to falling market interest rates); (3) credit risk (the possibility that a bond issuer will fail to make timely payments of either interest or principal to the Funds); (4) prepayment risk or call risk (the likelihood that, during periods of falling interest rates, securities with high stated interest rates will be prepaid, or “called” prior to maturity, requiring the Funds to invest the proceeds at generally lower interest rates); and (5) extension risk (the likelihood that as interest rates increase, slower than expected principal payments may extend the average life of fixed income securities, which will have the effect of locking in a below-market interest rate, increasing the security’s duration and reducing the value of the security).

In periods of declining interest rates, the yield (income from a fixed income security held by the Funds over a stated period of time) of a fixed income security may tend to be higher than prevailing market rates, and in periods of rising interest rates, the yield of a fixed income security may tend to be lower than prevailing market rates. In addition, when interest rates are falling, the inflow of net new money to the Funds will likely be invested in portfolio instruments producing lower yields than the balance of the Funds’ portfolio, thereby reducing the yield of the Funds. In periods of rising interest rates, the opposite can be true. The NAV of a Fund can generally be expected to change as general levels of interest rates fluctuate. The value of fixed income securities in the Funds’ portfolio generally varies

Additional Fund Information (cont.)

inversely with changes in interest rates. Prices of fixed income securities with longer effective maturities are more sensitive to interest rate changes than those with shorter effective maturities.

Corporate debt obligations generally offer less current yield than securities of lower quality, but lower-quality securities generally have less liquidity, greater credit and market risk, and as a result, more price volatility.

Conditions in the U.S. and many foreign economies have resulted, and may continue to result, in fixed income instruments experiencing unusual liquidity issues, increased price volatility and, in some cases, credit downgrades and increased likelihood of default. These events have reduced the willingness and ability of some lenders to extend credit, and have made it more difficult for borrowers to obtain financing on attractive terms, if at all. As a result, the values of many types of securities have been reduced. In addition, global economies and financial markets are becoming increasingly interconnected, which increases the possibilities that conditions in one country or region might adversely impact issuers in a different country or region. The severity or duration of adverse economic conditions may also be affected by policy changes made by governments or quasi-governmental organizations. In addition, political events within the U.S. and abroad, such as the U.S. government’s recent inability to agree on a long-term budget and deficit reduction plan, federal government shutdowns and threats to not increase the federal government’s debt limit, may affect investor and consumer confidence and may adversely impact financial markets and the broader economy, perhaps suddenly and to a significant degree. High public debt in the U.S. and other countries creates ongoing systemic and market risks and policymaking uncertainty.

Forward Commitments, When-Issued Securities and Delayed-Delivery Transactions. Each Fund may purchase securities on a when-issued basis or purchase or sell securities on a forward commitment (sometimes called delayed-delivery) basis. These transactions involve a commitment by a Fund to purchase or sell securities at a future date. The price of the underlying securities (usually expressed in terms of yield) and the date when the securities will be delivered and paid for (the settlement date) are fixed at the

time the transaction is negotiated. When-issued purchases and forward commitment transactions normally are negotiated directly with the other party.

The Funds will purchase securities on a when-issued basis or purchase or sell securities on a forward commitment basis only with the intention of completing the transaction and actually purchasing or selling the securities. If deemed advisable as a matter of investment strategy; however, each Fund may dispose of or negotiate a commitment after entering into it. Each Fund also may sell securities it has committed to purchase before those securities are delivered to the Fund on the settlement date. The Funds may realize a capital gain or loss in connection with these transactions.

When a Fund purchases securities on a when-issued, delayed-delivery or forward commitment basis, the Fund will segregate liquid assets having a value (determined daily) at least equal to the amount of the Fund’s purchase commitments until three days prior to the settlement date, or will otherwise cover its position. These procedures are designed to ensure that a Fund will maintain sufficient assets at all times to cover its obligations under when-issued purchases, forward commitments and delayed-delivery transactions. For purposes of determining a Fund’s average dollar-weighted maturity, the maturity of when-issued, delayed delivery or forward commitment securities will be calculated from the commitment date.

Illiquid Investments. An illiquid investment is defined under Rule 22e-4 under the 1940 Act as an investment that a Fund or an Underlying Fund reasonably expects cannot be sold or disposed of in current market conditions in 7 calendar days or less without the sale or disposition significantly changing the market value of the investment. A Fund may invest up to 15% of its net assets in illiquid investments. Illiquid investments may include repurchase agreements and time deposits with notice/termination dates of more than seven days, certain variable amount master demand notes that cannot be called within seven days, certain securities that are traded in the U.S. but are subject to trading restrictions because they are not registered under the Securities Act of 1933 (the “Securities Act”) and both foreign and domestic securities that are not readily marketable unless, based upon a review of the relevant

Additional Fund Information (cont.)

market, trading and investment-specific considerations, those investments are determined not to be illiquid.

Because illiquid securities may be difficult to sell at an acceptable price, they may be subject to greater volatility and may result in a loss to a Fund. Securities purchased by a Fund that are liquid at the time of purchase may subsequently become illiquid due to events relating to the issuer of the securities, market events, economic conditions and/or investor perception. The Trust has implemented a liquidity risk management program and related procedures to identify illiquid investments pursuant to Rule 22e-4, and the Trustees have approved the designation of the Investment Adviser to administer the Trust’s liquidity risk management program and related procedures. To the extent that an investment held by a Fund is deemed an illiquid investment or a less liquid investment, the Fund will be exposed to greater liquidity risk.

Inflation Risk. When inflation increases there is a risk that the value of assets or income from investments will be less in the future as the value of money decreases. As inflation increases, the value of the Funds’ assets can decline as can the value of the Funds’ distributions. Fixed income securities may be particularly sensitive to rising inflation, as the value of the security or income from the security will be worth less in the future as inflation decreases the value of money.

Inflation-Indexed Bonds. Inflation-indexed bonds (other than municipal inflation-indexed bonds and certain corporate inflation-indexed bonds, which are more fully described below) are fixed-income securities whose principal value is periodically adjusted according to the rate of inflation. If the index measuring inflation falls, the principal value of inflation-indexed bonds (other than municipal inflation indexed bonds and certain corporate inflation-indexed bonds) will be adjusted downward, and consequently the interest payable on these securities (calculated with respect to a smaller principal amount) will be reduced. Repayment of the original bond principal upon maturity (as adjusted for inflation) is guaranteed in the case of Treasury Inflation Protected Securities (TIPS). For bonds that do not provide a similar guarantee, the adjusted principal value of the bond repaid at maturity may be less than the original principal.

Municipal inflation-indexed securities are municipal bonds that pay coupons based on a fixed rate plus the Consumer Price Index for All Urban Consumers (“CPI”). With regard to municipal inflation-indexed bonds and certain corporate inflation-indexed bonds, the inflation adjustment is reflected in the semi-annual coupon payment. As a result, the principal value of municipal inflation-indexed bonds and such corporate inflation-indexed bonds does not adjust according to the rate of inflation. At the same time, the value of municipal inflation-indexed securities and such corporate inflation-indexed securities generally will not increase if the rate of inflation decreases. Because municipal inflation-indexed securities and corporate inflation-indexed securities are a small component of the municipal bond and corporate bond markets, respectively, they may be less liquid than conventional municipal and corporate bonds.

The value of inflation-indexed bonds is expected to change in response to changes in real interest rates. Real interest rates are tied to the relationship between nominal interest rates and the rate of inflation. If nominal interest rates increase at a faster rate than inflation, real interest rates may rise, leading to a decrease in value of inflation-indexed bonds. Any increase in the principal amount of an inflation-indexed bond will be considered taxable ordinary income, even though investors do not receive their principal until maturity.

Investment Companies. Each Fund may invest in securities of other investment companies, including other ETFs. Such investments may include money market funds and other ETFs managed by the Investment Adviser.

Investment Grade Securities. A security is considered investment grade if, at the time of acquisition, it is rated:

•BBB or higher by S&P Global Ratings (“S&P”);

•Baa3 or higher by Moody’s Investors Service, Inc. (“Moody’s”);

•BBB or higher by Fitch Ratings (“Fitch”); or

•BBB or higher by Dominion Bond Rating Service Limited (“Dominion”).

A security will be considered investment grade if it receives one of the above ratings, or a comparable rating from another organization that is recognized as a Nationally

Additional Fund Information (cont.)

Recognized Statistical Rating Organization (“NRSRO”), even if it receives a lower rating from other rating organizations. An unrated security also may be considered investment grade if the Investment Adviser determines that the security is comparable in quality to a security that has been rated investment grade.

Generally, the lower the credit rating of a security, issuer, guarantor or counterparty, the higher the degree of risk as to payment of interest and return of capital. Although securities rated BBB by S&P, Dominion or Fitch, or Baa3 by Moody’s are considered investment grade, they have certain speculative characteristics. Therefore, they may be subject to a higher risk of default than obligations with higher ratings. Subsequent to its purchase by a Fund, a rated security may cease to be rated or its rating may be reduced below investment grade or a security may no longer be considered to be investment grade. In such case, a Fund is not required to dispose of the security. The Investment Adviser will determine what action, including potential sale, is in the best interest of each Fund.

Investment Selection. When selecting securities for purchase or sale, and when evaluating whether to add, maintain or reduce exposure to any individual position, the Investment Adviser considers a number of factors. The Investment Adviser, as relevant for purchase or sale decisions, assesses broad macroeconomic trends (e.g., the prevailing interest rate environment or outlook); evaluates portfolio impact (e.g., duration management, potential tax consequences and transaction costs); and considers issuer-specific factors (e.g., credit profile, financial structure and pricing) to assess the value and risk of an individual security relative to other securities. Based upon the Investment Adviser’s outlook for the U.S. and global economies, the financial markets and other factors, the Investment Adviser from time to time will vary the amount of investment in and may or may not be invested in various sectors (e.g., governments, corporates, non-U.S. issuers, etc.).

Investments of Underlying Funds. Because the FlexShares® Core Select Bond Fund invests in the Underlying Funds, the Fund’s shareholders will be affected by the investment policies of the Underlying Funds in direct proportion to the amount of assets the Fund allocates to those Underlying Funds. The Fund may invest in Underlying

Funds that in turn invest in foreign issuers and thus are subject to additional risks, including country risk. Foreign investments of the Underlying Funds may include securities of issuers located in emerging countries in Asia, Latin America, Eastern Europe and Africa. The Fund may invest in Underlying Funds that invest in asset-backed and structured investment securities, which may involve a greater chance of default during periods of economic downturn than other securities, and may be less liquid and more difficult to value and liquidate.

The FlexShares® Core Select Bond Fund may invest in Underlying Funds that invest in obligations of state and local governments and thus may be adversely affected by volatility in the municipal market. The municipal market can be significantly affected by adverse tax, legislative, or political changes and the financial condition of the issuers of municipal securities.

The FlexShares® Core Select Bond Fund may also invest in actively managed Underlying Funds, which do not seek to replicate an index. There is no assurance that actively managed Underlying Funds will achieve their investment objectives.

Large Shareholder Risk. To the extent a significant percentage of the shares of a Fund are owned or controlled by a small number of account shareholders (or a single account shareholder), including funds or accounts over which the Investment Adviser or an affiliate of the Investment Adviser has investment discretion, the Fund is subject to the risk that those shareholders may purchase or redeem Fund shares in significant amounts rapidly or unexpectedly, including as a result of an asset allocation decision made by the Investment Adviser or an affiliate of the Investment Adviser and may adversely affect the Fund’s performance if the Investment Adviser is forced to sell portfolio securities or invests cash when the Investment Adviser would not otherwise choose to do so. Redemptions of a large number of shares may affect the liquidity of a Fund’s portfolio, increase the Funds’ transaction costs, and accelerate the realization of taxable income and/or gains. In addition, a large redemption could result in each Fund’s current expenses being allocated over a smaller asset base, leading to an increase in such Fund’s gross expense ratio. Large purchases of a Fund’s shares may also adversely affect

Additional Fund Information (cont.)

the Fund’s performance to the extent that a Fund is delayed in investing new cash or otherwise maintains a larger cash position than it ordinarily would to the extent that the Fund accepts cash for an order for the purchase of creation units of the Fund’s shares.

LIBOR Transition Risk. A Fund’s investments, payment obligations and financing terms may be based on floating rates, such as London Interbank Offered Rate (“LIBOR”). On July 27, 2017, the Chief Executive of the UK Financial Conduct Authority (“FCA”), which regulates LIBOR, announced a desire to phase out the use of LIBOR by the end of 2021. Although many LIBOR rates were phased out at the end of 2021 as intended, a selection of widely used USD LIBOR rates will continue to be published until June 2023 in order to assist with the transition. There remains uncertainty regarding the effect of the LIBOR transition process and therefore any impact of a transition away from LIBOR on the instruments in which a Fund invests cannot yet be determined. Although Federal Reserve Bank of New York has identified the Secured Overnight Financing Rate (“SOFR”) as the intended replacement to USD LIBOR, foreign regulators have proposed other interbank offered rates, such as the Sterling Overnight Index Average (“SONIA”), and other replacement rates, which could be adopted. There is no assurance that the composition or characteristics of any alternative reference rate will be similar to or produce the same value or economic equivalence as LIBOR or that instruments using an alternative rate will have the same volume or liquidity. This announcement and any additional regulatory or market changes that occur as a result of the transition away from LIBOR and the adoption of alternative reference rates may have an adverse impact on the value of a Fund’s investments, performance or financial condition, and might lead to increased volatility and illiquidity in markets that currently rely on LIBOR to determine interest rates.

Loan Participations and Assignments. Each Fund may invest in fixed- and floating-rate loans, which investments generally will be in the form of loan participations and assignments of portions of such loans. Participations and assignments involve special types of risk, including credit risk, interest rate risk, liquidity risk, and the risks of being a lender. If a Fund purchases a participation, it may only be

able to enforce its rights through the lender, and may assume the credit risk of the lender in addition to the borrower.

Model Risk. The allocation model utilized in a Fund’s securities selection process may not result in improved issuer creditworthiness, maximize returns or minimize risk, or be appropriate for every investor seeking a particular risk profile.

Mortgage Dollar Rolls. A mortgage dollar roll involves the sale by a Fund of securities for delivery in the future (generally within 30 days). The Fund simultaneously contracts with the same counterparty to repurchase substantially similar (same type, coupon and maturity) but not identical securities on a specified future date. During the roll period, a Fund loses the right to receive principal and interest paid on the securities sold. However, a Fund benefits to the extent of any difference between (a) the price received for the securities sold and (b) the lower forward price for the future purchase and/or fee income plus the interest earned on the cash proceeds of the securities sold. Successful use of mortgage dollar rolls depends upon the Investment Adviser’s ability to predict correctly interest rates and mortgage prepayments. If the Investment Adviser is incorrect in its prediction, a Fund may experience a loss. Unless the benefits of a mortgage dollar roll exceed the income, capital appreciation and gain or loss due to mortgage prepayments that would have been realized on the securities sold as part of the roll, the use of this technique will diminish a Fund’s performance.

For financial reporting and tax purposes, a Fund treats mortgage dollar rolls as two separate transactions: one involving the purchase of a security and a separate transaction involving a sale. The Funds currently do not intend to enter into mortgage dollar rolls that are accounted for as financing and does not treat them as borrowings.

Percentage Investment Limitations. Unless otherwise stated, all percentage limitations on Fund investments listed in this Prospectus will apply at the time of investment.

Repurchase Agreements. Each Fund may enter into repurchase agreements with financial institutions such as banks and broker-dealers that are deemed to be creditworthy by the Investment Adviser in amounts not exceeding 20% of a

Additional Fund Information (cont.)

Fund’s total assets. Repurchase agreements involve the purchase of securities by a Fund subject to the seller’s agreement to repurchase them at a mutually agreed upon date and price. In the event of a default, the Funds will suffer a loss to the extent that the proceeds from the sale of the underlying securities and other collateral are less than the repurchase price and the Funds’ costs associated with delay and enforcement of the repurchase agreement. In addition, in the event of bankruptcy, the Funds could suffer additional losses if a court determines that the Funds’ interest in the collateral is unenforceable by the Funds.

Each Fund intends to enter into transactions with counterparties that are creditworthy at the time of the transactions. There is always the risk that the Investment Adviser’s analysis of creditworthiness is incorrect or may change due to market conditions. To the extent that a Fund focuses its transactions with a limited number of counterparties, it will be more susceptible to the risks associated with one or more counterparties. With respect to collateral received in repurchase transactions or other investments, the Funds may have significant exposure to the financial services and mortgage markets. Such exposure, depending on market conditions, could have a negative impact on the Funds, including minimizing the value of any collateral.

Structured Securities. Each Fund may invest in structured securities to the extent consistent with its investment objective and strategies. Structured securities present additional risk that the interest paid to a Fund on a structured security will be less than expected. The value of such securities is determined by reference to changes in the value of specific currencies, interest rates, commodities, securities, indices or other financial indicators (the “Reference”) or the relative change in two or more References. The interest rate or the principal amount payable upon maturity or redemption may be increased or decreased depending upon changes in the applicable Reference. Examples of structured securities include, but are not limited to, asset -backed commercial paper, structured notes and other debt obligations, where the principal repayment at maturity is determined by the value of a specified security or securities index.

The terms of some structured securities may provide that in certain circumstances no principal is due at maturity and, therefore, a Fund could suffer a total loss of its investment. Structured securities may be positively or negatively indexed, so that appreciation of the Reference may produce an increase or decrease in the interest rate or value of the security at maturity. In addition, changes in the interest rates or the value of the security at maturity may be a multiple of changes in the value of the Reference. Consequently, structured securities may entail a greater degree of market risk than other types of securities. Structured securities also may be more volatile, less liquid and more difficult to accurately price than less complex securities due to their derivative nature. As a result, investments in structured securities may adversely affect a Fund’s NAV. In some cases it is possible that a Fund may suffer a total loss on its investment in a structured security.

Temporary Investments. Each Fund may temporarily hold cash and cash-like instruments or invest in short term obligations pending investment or to meet anticipated redemption requests. A Fund also may hold up to 100% of its total assets in cash or cash-like instruments or invest in short term obligations as a temporary measure mainly designed to limit the Funds’ losses in response to adverse market, economic or other conditions when the Investment Adviser believes that it is in the best interest of the Funds to pursue such a defensive strategy. The Investment Adviser may, however, choose not to make such temporary investments even in very volatile or adverse conditions. A Fund may not achieve its investment objective when it holds cash or cash-like instruments, or invests its assets in short-term obligations or otherwise makes temporary investments. A Fund also may miss investment opportunities and have a lower total return during these periods.

Variable and Floating Rate Instruments. Each Fund may invest in variable and floating rate instruments. Variable and floating rate instruments have interest rates that periodically are adjusted either at set intervals or that float at a margin tied to a specified index rate. These instruments include floating rate Treasury obligations, variable amount master demand notes, long-term variable and floating rate bonds where a Fund obtains at the time of purchase the right to put the bond back to the issuer or a third party at par at a specified date and leveraged inverse floating rate

Additional Fund Information (cont.)

instruments (“inverse floaters”). An inverse floater is leveraged to the extent that its interest rate varies by an amount that exceeds the amount of the variation in the index rate of interest. Some variable and floating rate instruments have interest rates that periodically are adjusted as a result of changes in inflation rates.

The market values of inverse floaters are subject to greater volatility than other variable and floating rate instruments due to their higher degree of leverage. Because there is no active secondary market for certain variable and floating rate instruments, they may be more difficult to sell if the issuer defaults on its payment obligations or during periods when a Fund is not entitled to exercise its demand rights. As a result, a Fund could suffer a loss with respect to these instruments. In addition, variable and floating rate instruments are subject to changes in value based on changes in market interest rates or changes in the issuer’s or guarantor’s creditworthiness.

Zero Coupon, Pay-In-Kind and Capital Appreciation Bonds. Each Fund may invest in zero coupon bonds and the FlexShares® Ultra-Short Income Fund may invest in pay-in-kind and capital appreciation bonds, to the extent consistent with its investment objective and strategies. These are securities issued at a discount from their face value because interest payments typically are postponed until maturity. Interest payments on pay-in-kind securities are payable by the delivery of additional securities. The amount of the discount rate varies depending on factors such as the time remaining until maturity, prevailing interest rates, a security’s liquidity and the issuer’s credit quality. These securities also may take the form of debt securities that have been stripped of their interest payments.

The market prices of zero coupon, pay-in-kind and capital appreciation bonds generally are more volatile than the market prices of interest-bearing securities and are likely to respond to a greater degree to changes in interest rates than interest-bearing securities having similar maturities and credit quality. Each Fund’s investments in zero coupon, pay-in-kind and capital appreciation bonds may require the Fund to sell some of its portfolio securities to generate sufficient cash to satisfy certain income distribution requirements.

Portfolio Holdings Information

A description of the Trust’s policies and procedures with respect to the disclosure of the Funds’ portfolio securities is available in the Funds’ SAI. The top holdings of each Fund can be found at flexshares.com. Fund fact sheets provide information regarding the Funds’ top holdings and may be requested by calling 1-855-FLEXETF (1-855-353-9383) or visiting the Trust’s website at flexshares.com.

Description of Fund Management

Investment Adviser

Northern Trust Investments, Inc. (“NTI” or the “Investment Adviser”), a subsidiary of Northern Trust Corporation, serves as the Investment Adviser of the Funds. NTI is located at 50 South LaSalle Street, Chicago, IL 60603.

NTI is an Illinois State Banking Corporation and an investment adviser registered under the Investment Advisers Act of 1940, as amended. It primarily manages assets for institutional and individual separately managed accounts, investment companies and bank common and collective funds. Northern Trust Corporation is regulated by the Board of Governors of the Federal Reserve System as a financial holding company under the U.S. Bank Holding Company Act of 1956, as amended.

As of December 31, 2022, Northern Trust Corporation, through its affiliates, had assets under investment management of $1.2 trillion and assets under custody of $10.6 trillion.

Under the Investment Advisory Agreement with the Funds, NTI, subject to the general supervision of the Trust’s Board of Trustees, is responsible for making investment decisions for the Funds and for placing purchase and sale orders for portfolio securities.

As compensation for its advisory services and assumption of Fund expenses, NTI is entitled to a unitary management fee (“Management Fee”), computed daily and payable monthly as reflected in the table below. From the unitary management fee, NTI pays most of the expenses of each Fund, including the cost of transfer agency, custody, fund administration, legal, audit and other services. However, it is not responsible for the fee payments under the Investment Advisory Agreement, distribution fees and expenses paid by the Funds under any distribution plan adopted pursuant to Rule 12b-1 under the 1940 Act ("12b-1 Fees"), interest expenses, brokerage commissions and other trading expenses, fees and expenses of the independent trustees and their independent legal counsel, taxes and other extraordinary costs such as (i) dividend expenses on short sales; (ii) non-routine items, including litigation expenses and proxy expenses; and (iii) expenses that the Fund has incurred but did not actually pay due to an expense offset arrangement, if applicable.

The table below reflects the unitary management fees paid in the last fiscal year by each Fund (expressed as a percentage of the Fund’s average daily net assets).

Fund	Unitary Management Fee (as a percentage of the Fund’s average daily net assets)
FlexShares® Ultra-Short Income Fund	0.25%
FlexShares® Core Select Bond Fund	0.35%

NTI has contractually agreed to reimburse a portion of the operating expenses of each Fund (other than 12b-1 Fees, tax expenses, extraordinary expenses, and acquired fund fees and expenses as calculated pursuant to Form N-1A (“Acquired Fund Fees and Expenses”)) so that “Total Annual Fund Operating Expenses After Expense Reimbursement” do not exceed the Fund’s Management Fee plus (+) .0049%. NTI has also contractually agreed in the case of the FlexShares® Core Select Bond Fund to waive Management Fees or reimburse certain expenses in an amount equal to the sum of (a) any Acquired Fund Fees and Expenses, if any, incurred by the Fund that are attributable to the Fund’s investment in Acquired Funds managed by NTI or an investment adviser controlling, controlled by, or under common control with NTI (“Affiliated Funds”); and (b) 0.05% or such lesser amount in Acquired Fund Fees and Expenses incurred by the Fund that are attributable to the Fund’s investment in Acquired Funds that are not Affiliated Funds until March 1, 2024. The contractual expense reimbursement arrangements are expected to continue until at least March 1, 2024 and will continue automatically thereafter for periods of one year (each such one-year period, a “Renewal Year”). The contractual arrangements may be terminated with respect to a Fund, as to any succeeding Renewal Year, by NTI or the Fund upon 60 days’ written notice prior to the end of the current Renewal Year. The Board of Trustees may terminate the arrangement at any time with respect to a Fund if it determines that it is in the best interest of the Fund and its shareholders.

NTI may reimburse additional expenses or waive all or a portion of the management fees of the Funds. Any such

Description of Fund Management (cont.)

additional expense reimbursement or fee waiver would be voluntary and could be implemented, increased or decreased, or discontinued at any time. A discussion regarding the Board of Trustees’ basis for its approval of the Advisory Agreement for each Fund is available in the Trust’s annual report to shareholders for the period ended October 31, 2022.

Portfolio Managers

NTI manages assets collectively on a team basis, which allows the firm to maintain continuity of the investment management process. NTI’s Chief Investment Officer leads various teams with respect to strategic overall investment management decisions and the development of investment strategies. Senior investment professionals from NTI’s portfolio management teams are involved in various aspects of managing the Funds. Portfolio managers within each specialized team are responsible for the day-to-day management of specific investment strategies and funds.

The individual Portfolio Managers who, as a team, are collectively responsible for the day-to-day management of the FlexShares® Ultra-Short Income Fund portfolio are:

Bilal Memon is a Senior Vice President of NTI. Mr. Memon joined NTI in 2007 and is responsible for managing various short duration portfolios.

Morten Olsen is a Senior Vice President of NTI. Mr. Olsen joined NTI in 2009 and has assisted in the management of various fixed-income funds.

The individual Portfolio Managers who, as a team, are collectively responsible for the day-to-day management of the FlexShares® Core Select Bond Fund’s portfolio are:

Bilal Memon is a Senior Vice President of NTI. Mr. Memon joined NTI in 2007 and is responsible for managing various short duration portfolios.

Morten Olsen is a Senior Vice President of NTI. Mr. Olsen joined NTI in 2009 and has assisted in the management of various fixed-income funds.

Chaitanya Mandavakuriti, CFA, is a Vice President of NTI. Mr. Mandavakuriti joined NTI in 2013 and has assisted in the management of international fixed income index portfolios with a focus on credit.

Additional information about the Portfolio Managers’ compensation, other accounts managed by the Portfolio Managers and the Portfolio Managers’ ownership of securities in the Funds is available in the SAI.

Description of Fund Management (cont.)

Administrator, Custodian, Transfer Agent and Securities Lending Agent

JPMorgan Chase Bank, N.A. (“JPMorgan”) is the administrator, custodian, transfer agent and securities lending agent for each Fund.

Distributor

Foreside Fund Services, LLC, a Delaware limited liability company, serves as the distributor (“Distributor”) of Creation Units for the Funds on an agency basis. The Distributor does not maintain a secondary market in shares of the Fund. The Distributor has no role in determining the policies of the Funds or the securities that are purchased or sold by the Funds. The Distributor’s principal address is Three Canal Plaza, Portland, Maine 04101. The Distributor is not affiliated with NTI or with JPMorgan or its affiliates.

Shareholder Information

Additional shareholder information is available free of charge by calling toll-free: 1-855-FLEXETF (1-855-353-9383) or visiting the Trust’s website at flexshares.com.

Buying and Selling Shares

Shares of the Funds trade on national securities exchanges during the trading day. Shares can be bought and sold throughout the trading day like other shares of publicly traded securities. There is no minimum investment. When buying or selling shares through a broker, you will incur customary brokerage commissions and charges. In addition, you will also incur the cost of the “spread,” which is the difference between what professional investors are willing to pay for Fund shares (the “bid” price) and the price at which they are willing to sell Fund shares (the “ask” price). The commission is frequently a fixed amount and may be a significant proportional cost for investors seeking to buy or sell small amounts of shares. The spread with respect to shares of a Fund varies over time based on the Fund’s trading volume and market liquidity, and is generally lower if the Fund has a lot of trading volume and market liquidity and higher if the Fund has little trading volume and market liquidity. Because of the costs of buying and selling Fund shares, frequent trading may reduce investment return and an investment in the Funds may not be advisable for investors who anticipate regularly making small investments.

Shares of the Funds may be acquired or redeemed directly from a Fund only in Creation Units or multiples thereof. Once created, shares of the Funds generally trade in the secondary market in amounts less than a Creation Unit.

Shares of the Funds trade under the trading symbol listed for each Fund on the front cover of this Prospectus.

The Trust’s Board of Trustees has adopted a policy whereby the Funds do not monitor for frequent purchases and redemptions of Fund shares (“frequent trading”). The Board of Trustees believes that a frequent trading monitoring policy is unnecessary for the Funds because shares of the Funds are listed and traded on national securities exchanges. Therefore, it is unlikely that a shareholder could take advantage of a potential arbitrage opportunity presented by a lag between a change in the value of a Fund’s portfolio securities after the close of the primary markets for the Fund’s portfolio securities and the reflection of that

change in the Fund’s NAV, because each Fund sells and redeems its shares directly through transactions that are in-kind and/or for cash.

The national securities exchanges on which the Funds are listed are open for trading Monday through Friday and are closed on weekends and the following holidays, as observed: New Year’s Day, Martin Luther King, Jr. Day, Presidents’ Day, Good Friday, Memorial Day, Juneteenth National Independence Day, Independence Day, Labor Day, Thanksgiving Day and Christmas Day.

Book Entry

Shares of the Funds are held in book-entry form, which means that no stock certificates are issued. The Depository Trust Company (“DTC”) or its nominee is the record owner of all outstanding shares of the Fund and is recognized as the owner of all shares for all purposes.

Investors owning shares of the Funds are beneficial owners as shown on the records of DTC or its participants. DTC serves as the securities depository for all shares of the Funds. DTC participants include securities brokers and dealers, banks, trust companies, clearing corporations and other institutions that directly or indirectly maintain a custodial relationship with DTC. As a beneficial owner of shares, you are not entitled to receive physical delivery of stock certificates or to have shares registered in your name, and you are not considered a registered owner of shares. Therefore, to exercise any rights as an owner of shares, you must rely upon the procedures of DTC and its participants. These procedures are the same as those that apply to any securities that you hold in book entry or “street name” form.

Share Prices

The trading prices of Fund shares in the secondary market may differ in varying degrees from their daily NAVs and can be affected by market forces such as supply and demand, economic conditions and other factors.

A Fund may determine to have the approximate value of its shares, known as the “indicative optimized portfolio value” (“IOPV”), disseminated every fifteen seconds throughout the trading day by the national securities exchange on which the Fund is listed or by other information providers

Shareholder Information (cont.)

or market data vendors. Any IOPV disseminated is based on the current market value of the securities and cash required to be deposited in exchange for a Creation Unit. Any IOPV disseminated does not necessarily reflect the precise composition of the current portfolio of securities held by a Fund at a particular point in time nor the best possible valuation of the current portfolio. Any IOPV disseminated should not be viewed as a “real-time” update of the NAV, because the IOPV may not be calculated in the same manner as the NAV, which is computed once a day as discussed below. Any IOPV disseminated is generally determined by using current market quotations and/or price quotations obtained from broker-dealers that may trade in the portfolio securities held by the Funds. The quotations of certain Fund holdings may not be updated during U.S. trading hours if such holdings do not trade in the U.S. The Funds are not involved in, or responsible for, the calculation or dissemination of an IOPV and make no warranty as to the accuracy of any disseminated IOPV.

Determination of Net Asset Value

Each Fund’s NAV is determined daily as of the close of regular trading on the New York Stock Exchange (“NYSE”), normally 4:00 p.m. Eastern time, on each day the NYSE is open for trading, based on prices at the time of closing, provided that any U.S. fixed-income assets may be valued as of the announced closing time for trading in fixed-income instruments on any day that the Securities Industry and Financial Markets Association announces an early closing time. The NAV of a Fund is calculated by dividing the value of all assets of a Fund (including accrued interest and dividends), less all liabilities (including accrued expenses and dividends declared but unpaid), by the total number of shares outstanding.

The investments of the Funds are valued at fair value pursuant to the pricing policy and procedures approved by the Board of Trustees. The Funds’ investments are valued using market quotations when available. The Board has designated NTI as the valuation designee pursuant to Rule 2a-5 under the 1940 Act to perform fair value determinations relating to any or all Fund investments. Accordingly, when market quotations are not readily available, are deemed unreliable, or do not reflect material events occurring

between the close of local markets and the time of valuation, NTI values Fund securities at fair value as determined in good faith in accordance with the Funds’ fair value pricing procedures as approved by the Board of Trustees. Such circumstances include periods when trading in a security is suspended, the exchange or market on which a security trades closes early, the trading volume in a security is limited, corporate actions and announcements take place, or regulatory news affecting an issuer is released, such as government approvals. The Board of Trustees oversees NTI in its role as valuation designee in accordance with the requirements of Rule 2a-5 under the 1940 Act. Additionally, the Trust, in its discretion, may make adjustments to the prices of securities held by a Fund if an event occurs after the publication of market values normally used by NTI on behalf of a Fund but before the time as of which the Fund calculates its NAV, depending on the nature and significance of the event, consistent with applicable regulatory guidance and the Trust’s fair value procedures. Other events that can trigger fair valuing of foreign securities include, for example, significant fluctuations in general market indicators, government actions, or natural disasters.

The use of fair valuation involves the risk that the values used by NTI to price a Fund's investments may be higher or lower than the values used by other investment companies and investors to price the same investments. Fair value pricing involves subjective judgments and it is possible that a fair value determination for a portfolio security may be materially different than the value that could be realized upon the sale of such security. Portfolio securities of certain Funds are listed on foreign exchanges and their value may change on days when shareholders will not be able to purchase or sell Fund shares.

Security prices are generally provided by independent pricing services. Portfolio securities listed or traded on domestic securities exchanges or the NASDAQ/NMS, including dollar-dominated foreign securities or American Depositary Receipts ("ADRs"), are valued at the closing price or last sale price reported on the exchange or system where the security is principally traded. The closing price for securities traded on the NASDAQ/NMS is the Nasdaq Official Closing Price (“NOCP”). If there have been no sales for that day on the exchange or system where the security is

Shareholder Information (cont.)

principally traded, then the value is determined with reference to the last sale price, or the NOCP, if applicable, on any other exchange or system. If there have been no sales of the security for that day on any exchange or system, the security is valued at fair value pursuant to the Trust’s fair value procedures.

Securities that are traded regularly in the over-the-counter market (other than the NASDAQ/NMS), including securities listed on exchanges but primarily traded over-the-counter, are valued on the basis of bid quotes or the mean between the bid and asked quotes based upon quotes furnished by one or more broker-dealers or market makers for those securities. Securities that may be traded over-the-counter include equity securities, fixed-income securities, non-exchange-listed foreign securities, and certain derivative instruments. Fixed income securities may be valued using prices provided directly from one or more broker-dealers, market makers, or independent third-party pricing services which may use matrix pricing and valuation models, as well as recent market transactions for the same or similar assets, to derive values when such prices are believed to reflect fair market values of such securities. Such prices may be determined by taking into account securities prices, yields, maturities, call features, ratings, prepayment speeds, credit risks, cash flows, institutional size trading in similar groups of securities and developments related to specific securities. Fixed-income securities maturing within a relatively short period, less than 60 days, are valued at amortized cost when fair value is approximated.

Foreign equity securities are generally priced at the closing price or last sales price reported on the foreign exchange on which they are principally traded. If there have been no sales for that day on the primary exchange, then the value is determined with reference to the last sale price on any other exchange. If there have been no sales of the security for that day on any exchange, the security will be valued at fair value pursuant to the Trust’s fair value procedures. Spot and forward foreign currency exchange contracts generally are valued using an independent pricing service. The value of assets denominated in foreign currencies is converted into U.S. dollars using exchange rates deemed appropriate by NTI as investment adviser.

Exchange-traded financial futures and options thereon are valued at the settlement price as established by the exchange on which they are traded. Over-the-counter options are valued at broker-provided bid prices, as are swaps. The foregoing prices may be obtained from one or more independent pricing services or, as needed or applicable, independent broker-dealers. If there was no sale on that day, and for non-exchange-traded derivatives, the contract is valued at fair value pursuant to the Trust’s fair value procedures.

Each Fund relies on various sources to calculate its NAV. The ability of the Funds’ administrator to calculate the NAV per share of the Funds is subject to operational risks associated with processing or human errors, systems or technology failures, and errors caused by third party service providers, data sources, or trading counterparties. Such failures may result in delays in the calculation of the Funds’ NAVs and/or the inability to calculate NAV over extended time periods. The Funds may be unable to recover any losses associated with such failures, and it may be necessary for alternative procedures to be followed to price portfolio securities when determining the Funds’ NAVs.

Distribution and Service Plan

The Trust has adopted a Distribution and Service Plan (the “Plan”) pursuant to Rule 12b-1 under the 1940 Act that allows each Fund to pay distribution and other fees for the sale and distribution of its shares. Because these fees would be paid out of each Fund’s assets on an on-going basis, over time these fees would increase the cost of your investment and may cost you more than paying other types of sales charges. Payments to financial intermediaries under the Plan are tied directly to their own out-of-pocket expenses. As of this date, the Plan has not been implemented with respect to the Funds. The Plan may not be implemented without further Board of Trustees approval. The maximum distribution fee is 0.25% of each Fund’s average net assets under the Plan. The Funds do not expect to pay any 12b-1 fees during the current and next fiscal years.

Shareholder Information (cont.)

Dividends and Distributions

Dividends from net investment income, including any net foreign currency gains, are generally declared and paid by each Fund according to the following schedule:

	Dividends from Net Investment Income:
Fund	Declared and Paid Quarterly	Declared and Paid Monthly
FlexShares® Ultra- Short Income Fund		✓
FlexShares® Core Select Bond Fund		✓

Distributions of net realized securities gains, if any, generally are declared and paid once a year, but the Trust may make distributions on a more frequent basis for the Funds. The Trust reserves the right to declare special distributions if, in its reasonable discretion, such action is necessary or advisable to improve tracking error, to preserve its status as a regulated investment company or to avoid imposition of income or excise taxes on undistributed income or realized gains.

Dividends and other distributions on shares are distributed on a pro rata basis to beneficial owners of such shares. Dividend payments are made through DTC participants to beneficial owners then of record with proceeds received from a Fund. Dividends and securities gains distributions are distributed in U.S. dollars and cannot be automatically reinvested in additional shares of the Funds.

No dividend reinvestment service is provided by the Trust. Broker-dealers may make available the DTC book-entry Dividend Reinvestment Service for use by beneficial own-ers of the Fund for reinvestment of their dividend distributions. Beneficial owners should contact their broker to determine the availability and costs of the service and the details of participation therein. Brokers may require beneficial owners to adhere to specific procedures and timetables. If this service is available and used, dividend distributions of both income and realized gains will be automatically reinvested in additional whole shares of the Fund purchased in the secondary market.

Tax Considerations

The following is a summary of certain tax considerations that may be relevant to an investor in a Fund. The discussions of the federal tax consequences in this Prospectus are based on the Internal Revenue Code of 1986, as amended (the “Code”), and the regulations issued under it, and court decisions and administrative interpretations, as in effect on the date of this Prospectus. Future legislative or administrative changes or court decisions may significantly alter the statements included herein, and any such changes or decisions may be retroactive. Except where otherwise indicated, the discussion relates to shareholders who are individual United States citizens or residents and is based on current tax law. You should consult your tax advisor for further information regarding federal, state, local and/or foreign tax consequences relevant to your specific situation.

Each Fund has elected and intends to qualify (or if newly organized, intends to elect and qualify) each year as a regulated investment company for federal income tax purposes, and to distribute to shareholders substantially all of its net investment income and net capital gain each year. Except as otherwise noted below, you will generally be subject to federal income tax on a Fund’s distributions to you. For federal income tax purposes, Fund distributions attributable to short-term capital gains and net investment income are taxable to you as ordinary income. Distributions attributable to net capital gain (the excess of net long-term capital gains over net short-term capital losses) of a Fund generally are taxable to you as long-term capital gains. This is true no matter how long you own your shares. The maximum long-term capital gain rate applicable to individuals, estates and trusts is 20%. Every year, you will be provided information detailing the amount of ordinary income and capital gains distributed to your account for the previous year.

Each Fund may invest in debt securities issued by state and local governments, the interest on which is exempt from Federal income taxes. However, a Fund will not be eligible to pay dividends that are exempt from Federal income taxes unless, after the end of each quarter, at least 50% of the value of the Fund’s assets are invested in tax exempt obligations. Each Fund does not expect to meet this requirement under normal circumstances.

Shareholder Information (cont.)

U.S. individuals with “modified adjusted gross income” exceeding $200,000 ($250,000 if married and filing jointly) will be subject to the Medicare contribution tax on their “net investment income,” which includes interest, dividends and capital gains at a rate of 3.8%.

Dividends and distributions from each Fund will generally be taxable to you in the tax year in which they are paid, with one exception. Dividends and distributions declared by a Fund in October, November or December and paid in January are taxed as though they were paid by December 31.

Distributions in excess of a Fund’s current and accumulated earnings and profits will, as to each shareholder, be treated as a tax-free return of capital and will reduce the shareholder’s basis in his shares of the Fund (but not below zero). To the extent such distribution exceeds the shareholder’s basis, the distribution will result in a capital gain (if the shareholder holds his shares of the Fund as capital assets) as if the shareholder sold his shares. Such capital gain will be long-term capital gain if the shareholder held the shares for more than one year.

The Funds may be subject to foreign withholding taxes with respect to interest received from sources in foreign countries. If at the close of the taxable year more than 50% in value of a Fund’s assets consists of securities of foreign corporations such Fund will be eligible to make an election to treat a proportionate amount of those taxes as constituting a distribution to each shareholder, which would allow you either (1) to credit that proportionate amount of taxes against U.S. Federal income tax liability as a foreign tax credit or (2) to take that amount as an itemized deduction. If a Fund is not eligible to make this election or if it is eligible but does not make the election, it will be entitled to deduct such taxes in computing the amounts it is required to distribute. The Funds do not expect to be eligible to make the election.

If you (a) have provided either an incorrect Social Security Number or taxpayer identification number or no number at all, (b) are subject to withholding by the Internal Revenue Service (“IRS”) for prior failure to properly include on your return payments of interest or dividends, or (c) have failed to certify, when required to do so, that you are not subject to backup withholding or are an “exempt

recipient,” then 24% of the dividends and distributions payable to you will be withheld and remitted to the IRS.

The sale or redemption of Fund shares is a taxable event on which a gain or loss may be recognized. The amount of gain or loss is based on the difference between your tax basis in the Fund shares and the amount you receive for them upon disposition. Generally, you will recognize long-term capital gain or loss if you have held your Fund shares for over twelve months at the time you dispose of them. Gains and losses on shares held for twelve months or less will generally constitute short-term capital gains, except that a loss on shares held six months or less will be recharacterized as a long-term capital loss to the extent of any capital gains distributions that you have received on the shares. A loss realized on a sale or exchange of Fund shares may be disallowed under the so-called “wash sale” rules to the extent the shares disposed of are replaced with other shares of that same Fund within a period of 61 days beginning 30 days before and ending 30 days after the shares are disposed of, such as pursuant to a dividend reinvestment in shares of the Fund. If disallowed, the loss will be reflected in an adjustment to the basis of the shares acquired.

The one major exception to the preceding tax principles is that distributions on, and sales, exchanges and redemptions of, shares held in an IRA or other tax-qualified plan will not be currently taxable unless shares are acquired with borrowed funds. Distributions may be taxable upon withdrawal from tax-advantaged accounts.

Except as stated below, you may be subject to state and local taxes on Fund distributions and redemptions. State income taxes may not apply, however, to the portions of each Fund’s distributions, if any, that are attributable to interest on certain types of federal securities or interest on securities issued by the particular state or municipalities within the state.

U.S. Tax Treatment of Foreign Shareholders. Nonresident aliens, foreign corporations and other foreign investors in the Funds will generally be exempt from U.S. federal income tax on Fund distributions attributable to net capital gains. The exemption may not apply, however, if the investment in a Fund is connected to a trade or business of the foreign investor in the United States or if the foreign

Shareholder Information (cont.)

investor is present in the United States for 183 days or more in a year and certain other conditions are met.

Fund distributions attributable to the other categories of Fund income, such as dividends from companies whose securities are held by a Fund and interest on debt securities, will generally be subject to a 30% withholding tax when paid to foreign shareholders. However, certain interest related dividends and short term capital gain dividends as designated by a Fund are not subject to this 30% withholding tax if the shareholder provides a properly completed Form W-8BEN or W-8BEN-E, as applicable. The withholding tax may, however, be reduced (and, in some cases, eliminated) under an applicable tax treaty between the United States and a shareholder’s country of residence or incorporation, provided that the shareholder furnishes the Fund with a properly completed Form W-8BEN, or W-8BEN-E, as applicable, to establish entitlement for these treaty benefits. In addition, the Funds will be required to withhold 30% tax on certain payments to foreign entities that do not meet specified information reporting requirements under the Foreign Account Tax Compliance Act.

A foreign investor will generally not be subject to U.S. tax on gains realized on sales or exchanges of Fund shares unless the investment in the Fund is connected to a trade or business of the investor in the United States or if the investor is present in the United States for 183 days or more in a year and certain other conditions are met. All foreign investors should consult their own tax advisors regarding the tax consequences in their country of residence of an investment in the Fund.

Taxes on Creations and Redemptions of Creation Units. A person who purchases a Creation Unit by exchanging securities in-kind generally will recognize a gain or loss equal to the difference between the market value of the Creation Units at that time, and the purchaser’s aggregate basis in the securities surrendered and any net cash paid. A person who redeems Creation Units and receives securities in-kind from a Fund will generally recognize a gain or loss equal to the difference between the redeemer’s basis in the Creation Units, and the aggregate market value of the securities received and any net cash received. The IRS, however, may assert that a loss realized upon an in-kind exchange of securities for Creation Units or an exchange of Creation

Units for securities cannot be deducted currently under the rules governing “wash sales,” or on a basis that there has been no significant change in economic position. Persons effecting in-kind creations or redemptions should consult their own tax adviser with respect to these matters.

Under current federal tax laws, any capital gain or loss realized upon redemption of Creation Units of a Fund is generally treated as long-term capital gain or loss if the Fund’s shares have been held for more than one year and as a short-term capital gain or loss if the Fund’s shares have been held for one year or less, assuming such Creation Units are held as a capital asset.

If a Fund redeems Creation Units in cash, it may recognize more capital gains than it will if it redeems Creation Units in-kind.

There are certain tax requirements that a Fund must follow in order to qualify as a regulated investment company and to avoid federal income taxation. In its efforts to adhere to these requirements, the Funds may have to limit its investment activity in some types of instruments.

Consult Your Tax Professional. Your investment in the Funds could have additional tax consequences. You should consult your tax professional for information regarding all tax consequences applicable to your investments in the Funds. More tax information is provided in the SAI. This short summary is not intended as a substitute for careful tax planning.

Householding

Householding is an option available to certain investors. Householding is a method of delivery, based on the preference of the individual investor, in which a single copy of certain shareholder documents can be delivered to investors who share the same address, even if their accounts are registered under different names. Householding is available through certain broker-dealers. If you are interested in enrolling in householding and receiving a single copy of prospectuses and other shareholder documents, please contact your broker-dealer. If you are currently enrolled in householding and wish to change your householding status, please contact your broker-dealer.

Financial Highlights

The financial highlights table is intended to help you understand the following Funds’ financial performance for the past five fiscal years or, if shorter, from commencement of operations through October 31, 2022. Certain information reflects financial results for a single share. This information has been audited by Deloitte & Touche LLP, an independent registered public accounting firm, whose report, along with the financial statements of the following Funds for the year ended October 31, 2022, is included in the annual report of the Funds and is available upon request.

	FlexShares® Ultra-Short Income Fund
	Year ended October 31,
	2022	2021	2020	2019	2018
Net Asset Value, beginning of period	$76.01	$76.29	$75.89	$75.48	$75.61
PER SHARE
Investment Operations
Net Investment Income	1.07 (a)	0.48 (a)	1.07 (a)	1.98 (a)	1.58 (a)
Net Realized and Unrealized Gain (Loss)	(1.80 )	(0.22 )	0.57	0.41	(0.24 )
Total from Operations	(0.73 )	0.26	1.64	2.39	1.34
Distributions
Net Investment Income	(0.78 )	(0.52 )	(1.23 )	(1.98 )	(1.47 )
From Net Realized Gains	(0.20 )	(0.02 )	(0.01 )	—	—
Total from Distributions	(0.98 )	(0.54 )	(1.24 )	(1.98 )	(1.47 )
Net Asset Value, end of period	$74.30	$76.01	$76.29	$75.89	$75.48
Total Return
Net Asset Value(d)	(0.94 )%	0.34 %	2.18 %	3.21 %	1.80 %
RATIOS/SUPPLEMENT DATA
Ratios to Average Net Assets
Expenses	0.26 %	0.26 %	0.26 %	0.26 %	0.26 %
Expenses net of reimbursements	0.25 %	0.25 %	0.25 %	0.25 %	0.25 %
Net Investment Income before reimbursements	1.43 %	0.62 %	1.41 %	2.61 %	2.09 %
Net Investment Income net of reimbursements	1.43 %	0.63 %	1.41 %	2.62 %	2.10 %
Supplemental Data
Portfolio Turnover Rate(e)	50 %	84 %	79 %	73 %	131 %
Net assets, end of period (thousands)	$856,357	$374,339	$469,201	$275,097	$211,350

Financial Highlights (cont.)

	FlexShares® Core Select Bond Fund
	Year ended October 31,				2018
	2022	2021	2020	2019	2018
Net Asset Value, beginning of period	$26.22	$26.78	$25.66	$23.74	$25.08
PER SHARE
Investment Operations
Net Investment Income	0.53 (a)	0.46 (a)	0.51 (a)	0.73 (a)	0.63 (a)
Net Realized and Unrealized Gain (Loss)	(4.75 )	(0.39 )	1.19	1.93	(1.31 )
Total from Operations	(4.22 )	0.07	1.70

	One Year	Five Year	Ten Year
Before Taxes	0.14%	1.47%	1.19%
After Taxes on Distributions	-0.55%	0.77%	0.66%
After Taxes on Distributions and Sale of Shares	0.08%	0.83%	0.68%
Bloomberg 1-3 Month U.S. Treasury Bill Index*	1.52%	1.22%	0.73%

Fund	Ticker	Stock Exchange
FlexShares® Ultra-Short Income Fund (formerly, FlexShares® Ready Access Variable Income Fund)	RAVI	NYSE Arca, Inc.
FlexShares® Core Select Bond Fund	BNDC	NYSE Arca, Inc.

Fund Summaries	2
FlexShares® Ultra-Short Income Fund	2
FlexShares® Core Select Bond Fund	9
Broad-Based Securities Market Indices	16
Additional Fund Information	17
Additional Information About the Funds’ Principal Risks	18
Additional Information About the Funds’ Investments and Other Risks	33
Portfolio Holdings Information	41
Description of Fund Management	42
Investment Adviser	42
Portfolio Managers	43
Administrator, Custodian, Transfer Agent and Securities Lending Agent	44
Distributor	44
Shareholder Information	45
Buying and Selling Shares	45
Book Entry	45
Share Prices	45
Determination of Net Asset Value	46
Distribution and Service Plan	47
Dividends and Distributions	48
Tax Considerations	48
Householding	50
Financial Highlights	51
Disclaimers	54
Supplemental Information	55
I. Premium/Discount Information	55
For More Information	Back Cover
Annual/Semi-Annual Reports and Statement of Additional Information (“SAI”)	Back Cover