Summary Prospectus by Investment Company (Form 497K)

FlexShares® Credit-Scored US Long

March 1, 2026

Ticker: LKOR

Stock Exchange: Cboe BZX Exchange, Inc.

Before you invest, you may want to review the Fund's statutory Prospectus, which contains more information about the Fund and its risks. You can find the Fund's statutory Prospectus, reports to shareholders, and other information about the Fund online at www.flexshares.com/prospectus. You can also get this information at no cost by calling 1-855-FLEXETF (1-855-353-9383) or by sending an e-mail request to [email protected]. The Fund's statutory Prospectus and Statement of Additional Information, both dated March 1, 2026, as supplemented, are incorporated by reference into this summary prospectus and may be obtained, free of charge, at the website, phone number or e-mail address noted above.

Investment Objective

The Fund seeks investment results that correspond generally to the price and yield performance, before fees and expenses, of the Northern Trust US Long Corporate Bond Quality Value IndexSM (the "Underlying Index").

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	0.15%
Distribution (12b-1) Fees	0.00%
Other Expenses	0.01%
Total Annual Fund Operating Expenses	0.16%
Expense Reimbursement(1)	-0.01%
Total Annual Fund Operating Expenses After Expense Reimbursement	0.15%

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 sell 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	$15
3 Years	$51
5 Years	$89
10 Years	$204

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 88% of the average value of its portfolio.

Principal Investment Strategies

The Underlying Index is designed to reflect the performance of a diversified universe of longer term maturity, US-dollar denominated bonds of companies with investment grade credit quality, favorable valuations, and enhanced short-term and long-term solvency. Securities eligible for inclusion in the Underlying Index must meet the following criteria at each reconstitution of the Underlying Index: (a) they are issued in U.S. dollars; (b) they are publicly issued in the U.S. and registered with the SEC or eligible for resale under Rule 144A under the Securities Act

www.flexshares.com

 

of 1933; (c) they fall within a specified list of eligible security types; (d) they are either senior or subordinated debts; (e) they have a minimum credit rating of Baa3 or BBB-; (f) they have a final maturity of 10 years or greater; and (g) they have $250 million or more in outstanding principal.

Once all eligible securities have been identified, the Underlying Index then follows a rules-based methodology to select and weight securities, subject to certain constraints as described below, to optimize the Underlying Index's exposure to a combined proprietary value score and a proprietary quality score, as determined by NTI acting in its capacity as index provider ("Index Provider"). Each of the value score and the quality score are based on various metrics obtained from company filings and recent price activity. The value score has multiple components, including: (a) valuation (e.g., to assess the relative value of the security versus other similar securities); (b) spread analysis (e.g., to assess the risk/return trade-off associated with each security versus other similar securities); and (c) solvency (e.g., to assess the corporation's short term and long term solvency and also its risk of default). The quality score has three components: (i) management efficiency (e.g., corporate finance activities); (ii) profitability (e.g., reliability and sustainability of financial performance); and (iii) solvency. The primary objective of the optimization process is to maximize exposure to securities with the highest value and quality scores and to maintain a similar effective duration profile relative to the Underlying Index's eligible universe. In addition, the optimization process also includes security level, sector, issuer level, low value and quality, duration band, and turnover constraints to seek to manage systematic risk.

As of December 31, 2025, there were 1,515 issues in the Underlying Index. The Underlying Index is reconstituted monthly. The Fund generally reconstitutes its portfolio in accordance with the Underlying Index.

NTI uses a "passive" or indexing approach to try to achieve the Fund's investment objective. Unlike many investment companies, the Fund does not try to "beat" the index it tracks and does not seek temporary defensive positions when markets decline or appear overvalued.

NTI uses representative sampling strategy to manage the Fund. "Representative sampling" is investing in a representative sample of securities that collectively has an investment profile similar to the Underlying Index. The Fund may or may not hold all of the securities that are included in the Underlying Index. The Fund reserves the right to

invest in substantially all of the securities in its Underlying Index in approximately the same proportions (i.e., replication) if NTI determines that it is in the best interest of the Fund.

The Fund generally will invest under normal circumstances at least 80% of its total assets (exclusive of collateral held from securities lending) in the securities of its Underlying Index. The Fund may also invest up to 20% of its assets in cash and cash equivalents, including shares of money market funds advised by NTI or its affiliates, futures contracts and options on futures, to-be-announced ("TBA") transactions, as well as securities not included in the Underlying Index, but which NTI believes will help the Fund track its Underlying Index.

The Underlying Index is created and sponsored by NTI, as the Index Provider. NTI also serves as the investment adviser to the Fund. The Index Provider determines the composition and relative weightings of the securities in the Underlying Index and publishes information regarding the market value of the Underlying Index.

The Fund may lend securities representing up to one-third of the value of the Fund's total assets (including the value of the collateral received).

Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated.

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. 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.

Corporate Bond Risk is the risk the Fund faces because it invests primarily in bonds issued by corporations. 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 can be expected to decline. Debt securities with longer maturities tend to be more sensitive to interest rate movements than those with shorter maturities.

Quality-Value Score Risk is the risk that the Fund's investment in companies whose securities are believed to be undervalued will not appreciate in value as anticipated or the past performance of companies that have exhibited quality characteristics does not continue. Although the Underlying Index is designed to measure the performance of a portfolio of bonds with certain characteristics, there is no assurance that the Underlying Index or Fund will be comprised of such securities or that the Underlying Index's optimization process will achieve the intended results.

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 the Underlying Index are substituted or the Fund otherwise needs to purchase additional bonds.

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, elevated levels of government debt, 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 financial institution failures, changes in trade regulation or economic sanctions, internal unrest and discord, 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. Such events 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.

Index Risk is the risk that the Fund would not necessarily buy or sell a security unless that security is added to or removed from, respectively, the Underlying Index, even if that security generally is underperforming, because unlike many investment companies, the Fund does not utilize an investing strategy that seeks returns in excess of the Underlying Index. Additionally, the Fund rebalances and/or

reconstitutes its portfolio in accordance with the Underlying Index, and, therefore, any changes to the Underlying Index's rebalance and/or reconstitution schedule will result in corresponding changes to the Fund's rebalance and/or reconstitution schedule.

Tracking Error Risk is the risk that the Fund's performance may vary from the performance of the Underlying Index as a result of creation and redemption activity, transaction costs, expenses and other factors. Market disruptions, regulatory restrictions or other abnormal market conditions could have an adverse effect on the Fund's ability to adjust its exposure to required levels in order to track its Index or cause delays in the Underlying Index's rebalancing schedule. During any such delay, it is possible that the Underlying Index, and, in turn, the Fund will deviate from the Underlying Index's stated methodology and therefore experience returns different than those that would have been achieved under a normal rebalancing or reconstitution schedule.

Sampling Risk is the risk that the Fund's use of a representative sampling approach may not work as intended and result in increased tracking error because the securities selected for the Fund in the aggregate may vary from the investment profile of the Underlying Index. Additionally, the use of a representative sampling approach may result in the Fund holding a smaller number of securities than the Underlying Index, and, as a result, an adverse development to an issuer of securities that the Fund holds could result in a greater decline in NAV than would be the case if the Fund held all of the securities in the Underlying Index.

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.

Calculation Methodology Risk is the risk that the Underlying Index's calculation methodology or sources of information may not provide an accurate assessment of included issuers or correct valuation of securities, nor is the

availability or timeliness of the production of the Underlying Index guaranteed. A security included in the Underlying Index may not exhibit the characteristic or provide the specific exposure for which it was selected and consequently a Fund's holdings may not exhibit returns consistent with that characteristic or exposure.

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.

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 prices 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 the 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.

•Options Contracts Risk Options contracts give the holder of the option the right to buy (or to sell) a position in a security or in a contract to the writer of the option, at a certain price. They are subject to correlation risk because there may be an imperfect correlation between the options and the securities markets that cause a given transaction to fail to achieve its objectives. The successful use of options depends on the investment adviser's ability to predict correctly future price fluctuations and the degree of correlation between the options and securities markets. Exchanges can limit the number of positions that can be held or controlled by the Fund or the investment adviser, thus limiting the ability to implement the Fund's strategies.

Concentration Risk is the risk that, if the Fund is concentrated in a particular industry or group of industries, the Fund is likely to present more risks than a fund that is broadly diversified over several industries or groups of industries. Compared to the broad market, an individual industry may be more strongly affected by changes in the economic climate, broad market shifts, moves in a particular dominant stock or regulatory changes.

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 incomes 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 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. In such cases, the Fund, due to limitations on investments in illiquid securities and/or purchasing and selling such investments, may be unable to achieve a high degree of correlation with the Underlying Index. 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.

Rule 144A Securities Risk is the risk that limitations on the resale of Rule 144A securities may have an adverse effect on their marketability and may prevent the Fund from disposing of them promptly at reasonable prices. There can be no assurance that an active trading market will exist at any time for such securities. Transaction costs may be higher for Rule 144A securities, and such securities may be difficult to value and may have significant volatility.

Foreign Issuer Risk is the risk that U.S. dollar-denominated securities of foreign issuers or U.S. affiliates of foreign issuers may be subject to additional risks not faced by domestic issuers. These risks include political and economic risks, civil conflicts and war, greater volatility, expropriation and nationalization risks, sanctions or other measures by the United States or other governments and regulatory issues facing issuers in such foreign countries.

Events and evolving conditions in certain economies or markets may alter the risks associated with investments tied to countries or regions that historically were perceived as comparatively stable, becoming riskier and more volatile. Foreign issuers may not be subject to uniform accounting, auditing and financial reporting standards and there may be less reliable and publicly available financial and other information about such issuers as compared to domestic issuers.

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 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.

TBA Transactions Risk is the risk of loss if the securities received are less favorable than what was anticipated by the Fund when entering into the TBA transaction. TBA transactions also involve the risk that the counterparty will fail to deliver the securities, exposing the Fund to further losses. Default or bankruptcy of a counterparty to a TBA transaction would expose the Fund to possible losses because of adverse market action, expenses or delays in connection with the purchase or sale of the pools of mortgage pass-through securities specified in the TBA transaction. Whether or not the Fund takes delivery of the securities at the termination date of a TBA transaction, the Fund will nonetheless be exposed to changes in the value of the underlying investments during the term of the agreement.

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.

Valuation Risk is the risk that the sale price the Fund could receive for a portfolio 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. In addition, 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.

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, (B) how the Fund's average annual returns compare with those of a broad-based securities market index and one or more style-specific indexes (reflecting the market segments in which the Fund invests), in that order. 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 (12/31/2023): 13.91%

Worst Quarter (6/30/2022): -12.95%

Average Annual Total Returns

(for the periods ended December 31, 2025) 

	One Year	Five Year	Ten Year
Before Taxes	7.27%	-2.75%	3.60%
After Taxes on Distributions	4.86%	-4.68%	1.60%
After Taxes on Distributions and Sale of Shares	4.26%	-2.83%	1.97%
Bloomberg U.S. Aggregate Bond Index**	7.30%	-0.36%	2.01%
Bloomberg Long U.S. Corporate Bond Index**	7.44%	-2.98%	3.42%
Hybrid Northern Trust Credit-Scored US Long Corporate Bond IndexSM/Northern Trust US Long Corporate Bond Quality Value IndexSM***	7.01%	-2.36%	4.16%

*** The hybrid index performance information reflects the performance of the Northern Trust Credit-Scored US Long Corporate Bond IndexSM (Previous Index) through April 30, 2020 and the Northern Trust US Long Corporate Bond Quality Value IndexSM thereafter. The Previous Index terminated as of May 1, 2020.

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. NTI manages assets collectively on a team basis. The following portfolio managers have the most significant responsibility for the day-to-day management of the Fund's portfolio. Benjamin Gord, a Senior Vice President and Head of Fixed Income Portfolio Implementation of NTI, Chaitanya Mandavakuriti, CFA, a Senior Vice President of NTI, and Manan Mehta, a Senior Vice President of NTI, have served as Portfolio Managers of the Fund since May 2023, March 2021 and July 2025, respectively.

Purchase and Sale of Fund Shares

The Fund is an exchange-traded fund (commonly referred to as 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.