Summary Prospectus by Investment Company (Form 497K)

OAKMSUMPRO

January 28, 2026, as amended and restated April 2, 2026

Summary Prospectus

Oakmark U.S. Large Cap ETF

OAKM

Before you invest, you may want to review the Fund's prospectus and statement of additional information, which contain more information about the Fund and its risks. You can find the Fund's prospectus and other information about the Fund online at oakmark.com/etfs/oakm. You can also get this information at no cost by calling 800-458-7452 or by sending an email request to [email protected]. You can also get this information from your financial intermediary or any financial intermediary authorized to sell the Fund's shares. The Fund's prospectus and statement of additional information, dated January 28, 2026, and as each may be further supplemented or amended, are incorporated by reference into this Summary Prospectus.

Investment objective

Oakmark U.S. Large Cap ETF seeks long-term capital appreciation.

Fees and expenses of the fund

Below are the fees and expenses that you would pay if you buy, hold, and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the table and example below.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

¹​ Harris Associates, L.P. (the "Adviser") has contractually undertaken to waive its management fee by 0.05% of the Fund's average daily net assets. The undertaking lasts until January 27, 2027 and may not be terminated during its term without the consent of the Board of Trustees.

Example. The 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 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 were those reflected in the table, inclusive of any fee waivers and/or expense reimbursements.

Although your actual returns and expenses may be higher or lower, based on these assumptions your expenses would be:

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. During the period from December 3, 2024 (commencement of operations) to the most recent fiscal year end, the Fund's portfolio turnover rate was 11% of the average value of its portfolio.

Principal investment strategy

Under normal circumstances, the Fund will invest at least 80% of its net assets (plus borrowings made for investment purposes) in securities of U.S. large capitalization companies. The Fund invests primarily in a diversified portfolio of common stocks of U.S. large capitalization companies. A large capitalization company is one whose market capitalizations is not smaller than the smallest market capitalization of a company in the Russell 1000 Index. As of December 31, 2025, the market capitalization range of the Russell 1000 Index was $1.0 billion to $3.8 trillion. In determining whether an issuer is a U.S. or foreign issuer the Adviser considers various factors, including its country of domicile, the primary stock exchange on which it trades, the location from which the majority of its revenue comes, and its reporting currency.

The Fund uses a value investment philosophy in selecting equity securities. This value investment philosophy is based upon the belief that, over time, a company's stock price converges with the Adviser's estimate of the company's intrinsic value. By "intrinsic value," the Adviser means its estimate of the price a knowledgeable buyer would pay to acquire the entire business. The Adviser believes that investing in securities priced significantly below what it believes is a company's intrinsic value presents the best opportunity to achieve the Fund's investment objective. A company trading below its estimated intrinsic value is sometimes referred to as trading at a discount.

The Adviser uses this value investment philosophy to identify companies that have discounted stock prices compared to what the Adviser believes are the companies' intrinsic values. In assessing such companies, the Adviser looks for the following characteristics, although the companies selected may not have all of these attributes: (1) free cash flows; (2) earnings that are growing and are reasonably predictable; and (3) high level of company management alignment with shareholders.

Key Tenets of the Oakmark Value Investment Philosophy:
1. Buy businesses that are trading at a significant discount to the Adviser's estimate of the company's intrinsic value. At the time the Adviser buys a company, the Adviser wants the company's stock to be inexpensive relative to what it believes the entire business is worth.
2. Invest with companies expected to grow shareholder value over time. Value investors can sometimes fall into the trap of buying a stock that is inexpensive for a reason-because the company just does not grow. The Adviser looks for businesses that are expected to achieve a combination of dividend yield and per-share growth in business value that is above-average.
3. Invest with management teams that think and act as owners. The Adviser seeks out companies with management teams that understand the dynamics of per share value growth and are focused on achieving such growth. Stock ownership and incentives that align managements' interests with those of shareholders are key components of this analysis.

In making its investment decisions, the Adviser uses a "bottom-up" approach focused on individual companies, rather than focusing on specific economic factors or specific industries.

To facilitate its selection of investments that meet the criteria described above, the Adviser uses independent, in-house research to analyze each company. As part of this selection process, the Adviser's analysts typically visit companies and conduct other research on the companies and their industries.

Once the Adviser identifies a stock that it believes is selling at a significant discount to the Adviser's estimated intrinsic value and that the company has one or more of the additional qualities mentioned above, the Adviser may consider buying that stock for the Fund. The Adviser usually sells a stock when the price approaches its estimated intrinsic value. This means the Adviser sets specific "buy" and "sell" targets for each stock the Fund holds. The Adviser monitors each portfolio holding and adjusts these price targets as warranted to reflect changes in a company's fundamentals.

The Adviser believes that holding a relatively small number of issuers allows its "best ideas" to have a meaningful impact on the Fund's performance. Therefore, the Fund's portfolio typically holds less than forty issuers rather than hundreds of issuers. The Fund invests in securities of large-capitalization companies.

The Fund will not change its policy to invest at least 80% of its net assets (plus borrowings made for investment purposes) in securities of U.S. large capitalization companies without providing shareholders at least 60 days' advance notice.

Principal investment risks

As an investor in the Fund, you should have a long-term perspective and be able to tolerate potentially wide fluctuations in the value of your Fund shares. Your investment in the Fund is subject to risks, including the possibility that the value of the Fund's portfolio holdings may fluctuate in response to events specific to the companies in which the Fund invests, as well as economic, political or social events in the U.S. or abroad and the Adviser's evaluation of those events, and the success of the Adviser in implementing the Fund's investment strategy. As a result, when you redeem your Fund shares, they may be worth more or less than you paid for them.

Your investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You may lose money by investing in the Fund. The likelihood of loss may be greater if you invest for a shorter period of time.

Although the Fund makes every effort to achieve its investment objective, it cannot guarantee it will attain that investment objective.

The following principal investment risks can significantly affect the Fund's performance:

Market Risk. The Fund is subject to market risk-the risk that securities markets and individual securities will increase or decrease in value. Market risk applies to every market and every security. Security prices may fluctuate widely over short or extended periods in response to adverse issuer, political, geopolitical (including wars or acts of terrorism), regulatory, market, economic, sanctions, tariffs, global health crises or pandemics, environmental, or other developments that may cause broad changes in market value, stability, and public perceptions concerning these developments, and adverse investor sentiment. In addition, securities markets tend to move in cycles. If there is a general decline in the securities markets, it is possible your investment may lose value regardless of the individual results of the companies in which the Fund invests. The magnitude of up and down price or market fluctuations over time is sometimes referred to as "volatility," which, at times, can be significant. In addition, different asset classes and geographic markets may experience periods of significant correlation with each other. As a result of this correlation, the securities and markets in which the Fund invests may experience volatility due to market, economic, political or social events, such as global health crises or pandemics, and conditions that may not readily appear to directly relate to such securities, the securities' issuer or the markets in which they trade. In addition, some companies may have substantial foreign operations or holdings and may involve additional risks relating to those markets, including but not limited to political, economic, regulatory, or other conditions in foreign countries, as well as currency exchange rates.

Focused Portfolio Risk. The Fund's portfolio tends to be invested in a relatively small number of issuers. As a result, the appreciation or depreciation of any one issuer held by the Fund will have a greater impact on the Fund's net asset value than it would if the Fund invested in a larger number of issuers. Although that strategy has the potential to generate attractive returns over time, it also increases the Fund's volatility and may lead to greater losses.

Common Stock Risk. Common stocks are generally subject to greater fluctuations in market value than other asset classes as a result of such factors as a company's business performance, investor perceptions, stock market trends and general economic conditions. The rights of common stockholders are subordinate to all other claims on a company's assets including, debt holders and preferred stockholders; therefore, the Fund could lose money if a company in which it invests becomes financially distressed.

Sector or Industry Risk. If the Fund has invested a higher percentage of its total assets in a particular sector or industry, changes affecting that sector or industry, or the perception of that sector or industry, may have a significant impact on the performance of the Fund's overall portfolio. Individual sectors or industries may be more volatile, and may perform differently, than the broader market.

Large Capitalization Risk. Investing primarily in issuers in one market capitalization category (large) carries the risk that due to current market conditions, that category may be out of favor with investors. Larger, more established companies may be unable to respond quickly to new competitive challenges or opportunities or attain the high growth rate of successful smaller companies.

Large Shareholder Risk. Certain large shareholders, including Authorized Participants, may from time to time own a substantial amount of the Fund's shares. There is no requirement that these shareholders maintain their investment in the Fund. There is a risk that such large shareholders or that the Fund's shareholders generally may redeem all or a substantial portion of their investments in the Fund in a short period of time, which could have a significant negative impact on the Fund's NAV, liquidity, and brokerage costs. Large redemptions could also result in tax consequences to shareholders and impact the Fund's ability to implement its investment strategy.

Value Style Risk. Investing in "value" stocks presents the risk that the stocks may never reach what the Adviser believes are their full market values, either because the market fails to recognize what the Adviser considers to be the companies' intrinsic values or because the Adviser misjudged those values. In addition, value stocks may fall out of favor with investors and underperform other investments during given periods.

ETF Risk. As an exchange-traded fund ("ETF"), the Fund is subject to the following risks:

Authorized Participants Concentration Risk. The Fund has a limited number of financial institutions that may act as Authorized Participants. To the extent they exit the business or are otherwise unable to proceed in creation and redemption transactions with the Fund and no other Authorized Participant is able to step forward to create or redeem, shares of the Fund may be more likely to trade at a premium or discount to net asset value ("NAV") and possibly face trading halts or delisting.

Cash Transactions Risk. The Fund may effect its creations and redemptions in cash or partially in cash. As a result, an investment in the Fund may be less tax-efficient than an investment in other ETFs that effect their creations and redemptions primarily on an in-kind basis.

Premium/Discount Risk. There may be times when the market price of the Fund's shares is more than the NAV intra-day (at a premium) or less than the NAV intra-day (at a discount). As a result, shareholders of the Fund may pay more than NAV when purchasing shares and receive less than NAV when selling Fund shares. This risk is heightened in times of market volatility or periods of steep market declines. In such market conditions, market or stop loss orders to sell Fund shares may be executed at prices well below NAV.

Secondary Market Trading Risk. Investors buying or selling shares in the secondary market will normally pay brokerage commissions, which are often a fixed amount and may be a significant proportional cost for investors buying or selling relatively small amounts of shares. Secondary market trading is subject to bid-ask spreads, which is the difference between the highest price a buyer is willing to pay to purchase shares of a fund (bid) and the lowest price a seller is willing to accept for shares (ask) when buying or selling shares in the secondary market, and trading in Fund shares may be halted by the Exchange because of market conditions or other reasons. If a trading halt occurs, a shareholder may

temporarily be unable to purchase or sell shares of the Fund. The bid-ask spread, which varies over time, is generally narrower if the Fund has more trading volume and market liquidity and wider if the Fund has less trading volume and market liquidity. In addition, the bid-ask spread can be affected by the liquidity of the Fund's underlying investments and can widen if the Fund's underlying investments become less liquid or illiquid. In addition, although the Fund's shares are listed on the Exchange, there can be no assurance that an active trading market for shares will develop or be maintained or that the Fund's shares will continue to be listed.

New Fund Risk. The Fund is a new fund, with a limited operating history, which may result in additional risks for investors in the Fund. There can be no assurance that the Fund will grow to an economically viable size, in which case the Fund may cease operations. In such an event, investors may be required to liquidate or transfer their investments at an inopportune time.

Performance information

The bar chart and performance table below can help you evaluate the potential risk and reward of investing in the Fund by showing changes in the performance of the Fund from year to year. The Fund's past performance (before and after taxes), as provided by the bar chart and performance table that follow, is not an indication of how the Fund will perform in the future. The performance table illustrates the volatility of the Fund's historical returns over various lengths of time and shows how the Fund's average annual returns compare with those of one or more broad measures of market performance. Updated performance information is available on Oakmark.com/etfs/oakm or by calling 1-800-458-7452.

Total Returns for Years Ended December 31

Since commencement of operation, the highest and lowest quarterly returns for the Fund were:

• Highest quarterly return: 6.5%, during the quarter ended December 31, 2025

• Lowest quarterly return: 4.0%, during the quarter ended March 31, 2025

Average Annual Total Returns for Periods Ended December 31, 2025

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 their shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts or individual retirement accounts. In some cases, the after-tax returns may exceed the return before taxes due to an assumed tax benefit from any losses on a sale of Fund shares at the end of the measurement period.

Investment adviser

Harris Associates L.P. is the Fund's investment adviser.

Portfolio managers

William C. Nygren, CFA, Michael A. Nicolas, CFA, and Robert F. Bierig manage the Fund's portfolio. Mr. Nygren is a Vice President, Chief Investment Officer, U.S. (until June 30, 2026), Co-Chief Investment Officer, U.S. (effective close of business June 30, 2026), and a portfolio manager of the Adviser. He joined the Adviser in 1983 and has managed the Fund since inception. Mr. Nicolas is a portfolio manager and analyst of the Adviser. He joined the Adviser in 2013 and has managed the Fund since inception. Mr. Bierig is Deputy Chairman (effective close of business June 30, 2026), Vice President (until June 30, 2026), portfolio manager and analyst of the Adviser. He joined the Adviser in 2012 and has managed the Fund since inception.

Purchase and sale of fund shares

The Fund issues shares to, and redeems shares from, certain institutional investors known as Authorized Participants (typically market makers or other broker-dealers who have entered into contractual arrangements with the Fund's distributor) only in large blocks of Fund shares known as "Creation Units." Creation Unit transactions are generally conducted in exchange for the deposit or delivery of a portfolio of in-kind securities designated by the Fund and a specified amount of cash.

Individual Fund shares may only be purchased and sold in the secondary market, such as a national securities exchange, through a broker or dealer at a market price. These transactions do not involve the Fund. Because Fund shares trade at market prices rather than at NAV, Fund shares may trade at a price greater than NAV (premium) or less than NAV (discount). When buying or selling shares in the secondary market, you 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) (the "bid-ask spread"). Most investors will incur customary brokerage commissions and charges when buying and selling shares of the Fund through a broker or dealer. Recent information regarding the Fund's NAV, market price, premiums and discounts, and bid-ask spreads is available at oakmark.com/etfs/oakm.

Tax information

The Fund's distributions may be taxable to you as ordinary income and/or capital gains, unless you are invested through a tax-deferred arrangement, such as a 401(k) plan or an individual retirement account.

Payments to broker-dealers and other financial intermediaries

If you purchase shares of the Fund through an intermediary, the Adviser or its affiliates may pay the intermediary for the sale of Fund shares and/or related services. These payments may create a conflict of interest by influencing the intermediary and your salesperson to recommend the Fund over another investment. Ask your salesperson or visit your intermediary's website for more information.