OpenAI Lab Ecosystem ETF Summary Prospectus

OpenAI Lab Ecosystem ETF

OAIW

Summary Prospectus – August 13, 2026

Before you invest, you may want to review the Fund’s prospectus, which contains more information about the Fund and its risks. You can find the Fund’s prospectus and other information about the Fund online at harborcapital.com/prospectus. You can also get this information at no cost by calling 800-422-1050 or by sending an email request to funddocuments@harborcapital.com. If you purchase shares of the Fund through a financial intermediary, the prospectus and other information will also be available from your financial intermediary. The current prospectus and statement of additional information, dated August 7, 2026, as amended or supplemented from time to time, are incorporated by referenced into this summary prospectus and may be obtained, free of charge, at the website, phone number or email address noted above.

Investment Objective

The Fund seeks to provide exposure to the portfolio-eligible companies most directly linked to the OpenAI artificial intelligence ecosystem.

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. 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)

Management Fees	0.59%
Distribution and Service (12b-1) Fees	None
Other Expenses1,2	0.00%
Total Annual Fund Operating Expenses	0.59%

1 Pursuant to the Investment Advisory Agreement, the Advisor pays all of the operating expenses of the Fund, except for (i) the fee payment under the Investment Advisory Agreement; (ii) payments under the Fund’s 12b-1 plan (if any); (iii) the costs of borrowing, including interest and dividend expenses; (iv) taxes and governmental fees; (v) acquired fund fees and expenses; (vi) brokers’ commissions and any other transaction-related expenses and fees arising out of transactions effected on behalf of the Fund; (vii) costs of holding shareholder meetings; and (viii) litigation and indemnification expenses and other extraordinary expenses not incurred in the ordinary course of the Fund’s business.

2 “Other Expenses” are estimated for the current fiscal year.

Expense Example

This Expense Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other exchange-traded funds. The Expense Example assumes that you invest $10,000 in the Fund for the time periods indicated. The Expense Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, under these assumptions, your costs would be:

One Year	Three Years
$60	$189

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 may indicate higher transaction costs and may result in higher taxes when shares of the Fund are held in a taxable account. These costs, which are not reflected in the Annual Fund Operating Expenses or in the Expense Example, do affect the Fund’s performance. The Fund had not commenced operations

as of the date of this Prospectus and no portfolio turnover rate existed at the time of this publication.

Principal Investment Strategy

The Fund is an actively managed exchange-traded fund that seeks to invest in a focused portfolio of companies that Harbor Capital Advisors, Inc. (the “Advisor”), the investment adviser to the Fund, believes to be most closely positioned to benefit from the success and growth of the OpenAI artificial intelligence ecosystem (“OpenAI Ecosystem Companies”).

The Advisor employs a proprietary model-driven thematic scoring process to identify and evaluate OpenAI Ecosystem Companies. Companies are assessed based on the Advisor’s analysis of the strength and materiality of their economic connection to the OpenAI ecosystem, drawing on a range of data sources including company filings, earnings call transcripts, news and media reports, supply-chain data, and market information. These scores are used as a primary input in the selection and weighting of securities in the portfolio.Portfolio holdings may include companies involved in cloud computing, semiconductors, memory and networking hardware, data center infrastructure, power and cooling systems, enterprise software, artificial intelligence deployment platforms, cybersecurity and other businesses that support or benefit from the development and adoption of OpenAI-related technologies and services.

Under normal circumstances, the Fund invests at least 80% of its net assets, plus borrowings for investment purposes, in equity securities of OpenAI Ecosystem Companies. The Fund may invest in U.S. and non-U.S. companies, including those in emerging market countries, and may invest in such companies directly or through depositary receipts. The Fund may also invest in privately offered securities, including Rule 144A securities and securities of companies that have recently completed or are expected to complete initial public offerings (IPOs). While the Fund may seek to invest directly in OpenAI, such company is not currently publicly traded and may not be available for investment by the Fund. Such investments in privately offered securities, if available at all, would be limited to 15% of the Fund’s net assets. Accordingly, an investor should not invest in the Fund with the expectation of obtaining direct exposure to securities of OpenAI.

The Fund is classified as non-diversified, which means the Fund may invest a greater percentage of its assets in a smaller number of issuers than a diversified fund. As a result, the performance of a limited number of issuers may have a significant effect on the Fund’s overall performance and volatility. The Fund will concentrate its investments (i.e., hold more than 25% of its total assets) in the industries and groups of industries comprising the information technology, communication services, industrials, consumer discretionary and utilities sectors.

The Fund is designed to maintain focused exposure to the OpenAI ecosystem across market cycles and does not employ a defensive investment approach based on the Advisor’s views regarding the performance or prospects of OpenAI or related technologies. The

Summary Prospectus

OpenAI Lab Ecosystem ETF

Fund’s investment strategy may result in a high level of portfolio turnover.

None of the Fund, Harbor ETF Trust or the Advisor is affiliated, connected or associated with OpenAI. The Fund was not developed or created by and is not sponsored, endorsed or approved by OpenAI.

Principal Risks

There is no guarantee that the investment objective of the Fund will be achieved. Stocks fluctuate in price and the value of your investment in the Fund may go down. This means that you could lose money on your investment in the Fund or the Fund may not perform as well as other investment options. Principal risks impacting the Fund (in alphabetical order after the first 7 risks) include:

OpenAI Ecosystem Risk: The Fund’s performance is closely tied to the success, adoption, and commercial growth of OpenAI and technologies associated with the OpenAI ecosystem. As a result, the Fund may be adversely affected by developments impacting OpenAI, including increased competition, technological disruption, regulatory actions, reputational harm, litigation, changes in strategic relationships, reduced enterprise adoption, or a decline in market interest in OpenAI-related products and services. The Fund may also be adversely affected if competing artificial intelligence platforms, models, or ecosystems achieve greater commercial success, technological advancement, market adoption, developer engagement, or investor interest than OpenAI. Because the Fund maintains focused exposure to companies economically connected to the OpenAI ecosystem, the Fund may underperform broader equity markets or other technology-focused investments during periods in which OpenAI-related companies are out of favor or experience negative market sentiment. Public statements—including public remarks and social media activity—by OpenAI leadership may introduce uncertainty and/or cause fluctuations in sentiment around OpenAI. Changes in OpenAI’s leadership may also affect investor sentiment.

Artificial Intelligence Risk: Companies involved in artificial intelligence and related technologies are subject to intense competition, rapid technological change, evolving industry standards, short product cycles, and significant research and development expenditures. The Fund’s investments may include companies whose products or services may become obsolete or less competitive as new technologies emerge. Many of these companies depend on intellectual property rights, access to computing capacity and specialized hardware, complex supply chains, and continued capital investment to maintain their competitive positions. Failures, delays, security vulnerabilities, operational disruptions, or reduced demand for AI-related products and services could adversely affect such companies.The issuers are also subject to legal, regulatory and political changes that may have a large impact on their profitability. AI technology could face increasing regulatory scrutiny in the future, which may limit the development of this technology and impede the growth of companies that develop and/or utilize this technology. Similarly, the collection of data from consumers and other sources could face increased scrutiny as regulators consider how the data is collected, stored, safeguarded and used. Companies may face regulatory fines and penalties, including potential forced break-ups, that could hinder the ability of the companies to operate on an ongoing basis. Country, government, and/or region-specific regulations or restrictions could have an impact on AI and big data companies.

Market Risk: Securities markets are volatile and can decline significantly in response to adverse market, economic, political, regulatory or other developments, which may lower the value of securities held by the Fund, sometimes rapidly or unpredictably. Events such as war, military conflict, geopolitical disputes, acts of terrorism, social or political unrest, natural disasters, recessions, inflation, rapid interest rate changes, supply chain disruptions, tariffs and other restrictions on trade, sanctions, the spread of infectious illness or other public health threats, or the threat or potential of one or more such events and developments, could also significantly impact the Fund and its investments.

Equity Risk: The values of equity securities may decline due to general market conditions that are not specifically related to a particular company, such as real or perceived adverse economic conditions, changes in the general outlook for corporate earnings, changes in interest or currency rates or adverse investor sentiment generally. They may also decline due to factors that affect a particular industry or industries, such as labor shortages or increased production costs and competitive conditions within an industry. Equity securities generally have greater price volatility than fixed income securities.

Non-Diversification Risk: Because the Fund is non-diversified and may invest a greater percentage of its assets in securities of a single issuer, and/or invest in a relatively small number of issuers, it is more susceptible to risks associated with a single economic, political or regulatory occurrence than a more diversified portfolio.

Data Risk: The Fund’s investment process relies on data and information obtained from a variety of sources, which may be incomplete, inaccurate, delayed, inconsistent, or unavailable. Errors in data collection, processing, or interpretation may affect the Advisor’s assessment of a company’s relationship to the OpenAI ecosystem. The Advisor’s assessment of a company’s relationship to the OpenAI ecosystem could be incorrect, which could negatively impact the Fund’s ability to provide the intended exposure to OpenAI Ecosystem Companies. In addition, the Fund’s investment process relies in part on proprietary analytical models and methodologies to analyze such data and information that may not operate as intended under all market conditions.

Risks Associated with Exchange-Traded Funds: As an ETF, the Fund is subject to the following risks:

Authorized Participant Concentration/Trading Risk: Only authorized participants (“APs”) may engage in creation or redemption transactions directly with the Fund. The Fund has a limited number of institutions that may act as APs and such APs have no obligation to submit creation or redemption orders. Consequently, there is no assurance that APs will establish or maintain an active trading market for the shares. This risk may be heightened to the extent that securities held by the Fund are traded outside a collateralized settlement system. In that case, APs may be required to post collateral on certain trades on an agency basis (i.e., on behalf of other market participants), which only a limited number of APs may be able to do. In addition, to the extent that APs exit the business or are unable to proceed with creation and/or redemption orders with respect to the Fund and no other AP is able to step forward to create or redeem Creation Units (as defined below), this may result in a significantly diminished trading market for shares, and shares may be more likely to trade at a premium or discount to the Fund’s net asset value and to face trading halts and/or delisting. This risk may be heightened during periods of volatility or market disruptions.

Cash Transactions Risk: The Fund may effect some or all of its creations and redemptions for cash rather than in-kind. As a result, an investment in the Fund may be less tax-efficient than an

Summary Prospectus

OpenAI Lab Ecosystem ETF

investment in an ETF that effects all of its creations and redemptions in-kind. Because the Fund may effect redemptions for cash, it may be required to sell portfolio securities in order to obtain the cash needed to distribute redemption proceeds. A sale of portfolio securities may result in capital gains or losses and may also result in higher brokerage costs. To the extent costs are not offset by transaction fees charged by the Fund to APs, the costs of cash transactions will be borne by the Fund.

Large Shareholder Risk: Certain large shareholders, including APs, 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. In addition, transactions by large shareholders may account for a large percentage of the trading volume on the listing exchange and may, therefore, have a material upward or downward effect on the market price of the shares.

Premium/Discount Risk: The market price of the Fund’s shares will generally fluctuate in accordance with changes in the Fund’s net asset value as well as the relative supply of and demand for shares on the Exchange. The Advisor cannot predict whether shares will trade below, at or above their net asset value because the shares trade on the Exchange at market prices and not at net asset value. Price differences may be due, in large part, to the fact that supply and demand forces at work in the secondary trading market for shares will be closely related, but not identical, to the same forces influencing the prices of the holdings of the Fund trading individually or in the aggregate at any point in time. This may result in the Fund’s shares trading significantly above (premium) or below (discount) the Fund’s net asset value, which will be reflected in the intraday bid/ask spreads and/or the closing price of shares as compared to net asset value. During stressed market conditions, the market for the Fund’s shares may become less liquid in response to deteriorating liquidity in the market for the Fund’s underlying portfolio holdings, which could in turn lead to differences between the market price of the Fund’s shares and their net asset value. To the extent securities held by the Fund trade on foreign exchanges that are closed while the Fund’s shares continue to trade in the United States, the value of those securities used to calculate the Fund’s NAV may differ from their current market value. As a result, the Fund’s shares may trade at a premium or discount to NAV, and bid/ask spreads may be wider than those of funds investing primarily in U.S. securities.

Depositary Receipts Risk: Depositary receipts are certificates evidencing ownership of shares of a foreign issuer. These certificates are issued by depository banks and generally trade on an established market in the U.S.or elsewhere. The underlying shares are held in trust by a custodian bank or similar financial institution. The depository bank may not have physical custody of the underlying securities at all times and may charge fees for various services, including forwarding dividends and interest and corporate actions. Depositary receipts are alternatives to directly purchasing the underlying foreign securities in their national markets and currencies. The issuers of depositary receipts may discontinue issuing new depositary receipts and withdraw existing depositary receipts at any time, which may result in costs and delays in the distribution of the underlying assets to the Fund and may negatively impact the Fund’s performance. Depositary receipts are subject to the risks associated with investing directly in foreign securities.

Foreign Securities Risk: Because the Fund may invest in securities of foreign issuers, including those located in emerging markets, an investment in the Fund is subject to special risks in addition to those of U.S. securities. These risks include heightened political and economic risks, greater volatility, currency fluctuations, higher transaction costs, delayed settlement, possible foreign controls on investment, possible sanctions by governmental bodies of other countries and less stringent investor protection and disclosure standards of foreign markets. Foreign securities are sometimes less liquid and harder to value than securities of U.S. issuers. These risks are more significant for issuers in emerging market countries. Global economies and financial markets are becoming increasingly interconnected, and conditions and events in one country, region or financial market may adversely impact issuers in a different country, region or financial market.

High Portfolio Turnover Risk: Higher portfolio turnover may adversely affect Fund performance by increasing Fund transaction costs and may lead to the realization and distribution to shareholders of higher capital gains, which may increase a shareholder’s tax liability.

IPO Risk: An IPO presents the risk that the market value of IPO shares will fluctuate considerably due to factors such as the absence of a prior public market, unseasoned trading, the small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs. IPO shares are subject to market risk and liquidity risk. Because of the price volatility of IPO shares, the Fund may choose to hold IPO shares for a very short period of time. This may increase the turnover of a portfolio and may lead to increased expenses to the Fund, such as commissions and transaction costs. The Fund’s investments in IPO shares may include the securities of “unseasoned” companies (companies with less than three years of continuous operations), which present risks considerably greater than common stocks of more established companies. These companies may have limited operating histories and their prospects for profitability may be uncertain.

Issuer Risk: An adverse event affecting a particular issuer in which the Fund is invested, such as an unfavorable earnings report, may depress the value of that issuer’s securities, sometimes rapidly or unpredictably.

Model Risk: There are limitations inherent in every quantitative model. The value of securities selected using quantitative analysis can react differently to issuer, political, market, and economic developments than the market as a whole or securities selected using only fundamental analysis. The factors used in quantitative analysis and the weight placed on those factors may not be predictive of a security’s value. In addition, historical trends in data may not be predictive going forward. The strategies and techniques employed in a quantitative model cannot fully match the complexity of the financial markets and therefore sudden unanticipated changes in underlying market conditions can significantly impact their performance. The effectiveness of the given strategy or technique may deteriorate in an unpredictable fashion for any number of reasons including, but not limited to, an increase in the amount of assets managed or the use of similar strategies or techniques by other market participants and/or market dynamic shifts over time. In addition, factors that affect a security’s value can change over time, and these changes may not be reflected in the quantitative model. Any model may contain flaws the existence and effect of which may be discovered only after the fact or not at all. In addition, artificial intelligence tools used as part of a model may be subject to one or more undetected errors, defects or security vulnerabilities, and there is a risk that any particular output will be incomplete, inaccurate, unreliable or otherwise flawed. There can be no

Summary Prospectus

OpenAI Lab Ecosystem ETF

assurances that the strategies pursued or the techniques implemented in the quantitative model will be profitable, and various market conditions may be materially less favorable to certain strategies than others. Even in the absence of flaws, a model may not perform as anticipated.

New Fund Risk: There can be no assurance that the Fund will grow to or maintain an economically viable size, in which case the Board of Trustees may determine to liquidate the Fund. The Board of Trustees may liquidate the Fund at any time in accordance with the Declaration of Trust and governing law. As a result, the timing of the Fund’s liquidation may not be favorable.

Privately Held Company Risk: Investments in equity securities of privately held companies involve greater risk than investments in equity securities of public companies. Because there is no public market for the company’s securities, it can be difficult to determine current valuations for the overall company and the related securities held by the Fund. Further, the Fund would not be able to sell these securities until a liquidity event occurs, such as an initial public offering of the company’s stock, which is normally outside the control of the Fund and Advisor. Accordingly, these securities are considered illiquid. There is also significantly less information available about these companies’ business models, quality of management, earnings growth potential and other criteria used to evaluate their investment prospects.

Sector Exposure Risk: Because the Fund may, from time to time, have significant exposure to particular sectors, the value of its shares may be especially sensitive to factors and economic risks that specifically affect those sector(s). As a result, the Fund’s share price may fluctuate more widely than the value of shares of a fund that invests in a broader range of exposures. The Fund may invest a significant portion of its assets in the following sector(s) and, therefore, the performance of the Fund could be negatively impacted by events affecting each of these sector(s).

Information Technology Sector Risk: Companies in the information technology sector can be significantly affected by short product cycles, obsolescence of existing technology, impairment or loss of intellectual property rights, falling prices and profits, competition from new market entrants, government regulation and other factors.

Communication Services Sector Risk: The performance of companies in the communication services sector may be affected by intense competition, rapid technological change, evolving consumer preferences, significant capital requirements, government regulation, public scrutiny, cybersecurity incidents, and the potential obsolescence of products or services. Communication services companies may also be affected by changes in advertising demand, user engagement, content distribution, data privacy rules, intellectual property matters, and the adoption or disruption of services through artificial intelligence technologies. Because the Fund may invest a significant portion of its assets in this sector, developments affecting communication services companies may have a greater impact on the Fund than on a fund with broader sector exposure.

Industrials Sector Risk: Companies in the industrials sector may be affected by supply and demand for their products and services, economic cycles, commodity prices, labor costs, transportation costs, government regulation, defense spending, infrastructure spending, trade policy, and global competition. Companies in this sector may be sensitive to changes in business investment and industrial production.

Consumer Discretionary Sector Risk: Companies in the consumer discretionary sector may be affected by changes in domestic and global economic conditions, interest rates, disposable household income, consumer confidence, consumer spending, competition, demographics, and changing consumer preferences. Consumer

discretionary companies may be more sensitive to economic downturns than companies in other sectors.

Utilities Sector Risk: Companies in the utilities sector may be affected by supply and demand, fuel costs, operating costs, government regulation, environmental regulation, liabilities for environmental damage, rate caps, rate changes, infrastructure spending, weather events, and interest rate changes. Because many utilities are regulated, their profitability may depend on regulatory approvals and permitted rates of return.

Unrelated Business Risk: Many of the companies in which the Fund will invest have other business lines unrelated to the Fund’s thematic category. These other lines of business could adversely affect those firms’ operating results and, in turn, hurt the Fund’s performance. The operating results of companies with other business lines may fluctuate independently of the fluctuations in the relevant thematic category businesses. In addition, a particular company’s ability to engage in new business activities may expose it to additional risks for which it has less experience than its existing business lines. Despite a company’s possible success in activities linked to a thematic category, there can be no assurance that its other lines of business will not adversely affect the company’s business, financial condition, or market value. In addition, a particular company’s unrelated businesses may impact the Fund’s investment returns and it may be difficult to isolate thematic category-related returns from other return sources.

Valuation Risk: Some portfolio holdings may be valued on the basis of factors other than market quotations. This may occur more often in times of market turmoil or reduced liquidity. There are multiple methods that can be used to value a portfolio holding when market quotations are not readily available. The value established for any portfolio holding at a point in time might differ from what would be produced using a different methodology or if it had been priced using market quotations. Portfolio holdings that are valued using techniques other than market quotations, including “fair valued” securities, may be subject to greater fluctuation in their valuations from one day to the next than if market quotations were used. In addition, there is no assurance that the Fund could sell or close out a portfolio position for the value established for it at any time, and it is possible that the Fund would incur a loss because a portfolio position is sold or closed out at a discount to the valuation established by the Fund at that time.

Performance

Because the Fund does not yet have a complete calendar year of performance history, the bar chart and total return tables are not provided. Once the Fund has operated for at least one calendar year, a bar chart and performance table will be included in the prospectus to show the performance of the Fund. When such information is included, this section will provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance history from year to year and showing how the Fund’s average annual total returns compare with those of a broad measure of market performance and an additional index. Please note that the Fund’s past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. To obtain performance information, please visit the Fund’s website at harborcapital.com or call 800-422-1050.

Summary Prospectus

OpenAI Lab Ecosystem ETF

Portfolio Management

Investment Advisor

Harbor Capital Advisors, Inc.

Portfolio Managers

The portfolio managers are jointly and primarily responsible for the day-to-day investment decision making for the Fund.

Spenser P. Lerner, CFA, Head of Multi-Asset Solutions, Managing Director and Portfolio Manager of Harbor Capital Advisors, Inc., has managed the Fund since 2026.

Justin Menne, CFA, Head of Global Equities at Harbor Capital Advisors, Inc., has managed the Fund since 2026.

Jonathan G. Poynter, PhD, CFA, Head of Quantitative Research at Harbor Capital Advisors, Inc., has managed the Fund since 2026.

Buying and Selling Fund Shares

Individual Fund shares may only be bought and sold in the secondary market through a broker or dealer at a market price. Shares of the Fund are listed and traded on an exchange at market price throughout the day rather than at NAV and may trade at a price greater than the Fund’s NAV (premium) or less than the Fund’s NAV (discount). An investor may incur costs attributable to the difference between the highest price a buyer is willing to pay to purchase shares (bid) and the lowest price a seller is willing to accept for shares (ask) when buying or selling Fund shares in the secondary market (the “bid-ask spread”). Recent information, including information regarding the Fund’s NAV, market price, premiums and discounts, and bid-ask spread, is available at harborcapital.com.

Tax Information

Distributions you receive from the Fund are subject to federal income tax and may also be subject to state and local taxes. These distributions will generally be taxed as ordinary income, capital gains, unless you are investing through a tax-deferred retirement account, such as a 401(k) plan or individual retirement account. Investments in tax-deferred accounts may be subject to tax when they are withdrawn.

Payments to Broker-Dealers and Other Financial Intermediaries

The Advisor and/or its related companies have in the past and could in the future pay intermediaries, which may include banks, broker-dealers, or financial professionals, for marketing activities and presentations, educational training programs, conferences, the development of technology platforms and reporting systems and data or other services related to the sale of Fund shares and related services. These payments create a conflict of interest by influencing the broker-dealer or other intermediary and your sales representative to recommend the Fund over another investment. Ask your sales representative or visit your financial intermediary’s website for more information.

Exchange	Ticker

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