Summary Prospectus by Investment Company (Form 497K)

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 Statement of Additional Information ("SAI") and other information about the Fund online at https://www.im.natixis.com/us/mutual-funds/vaughan-nelson-emerging-markets-fund/ADVMX. You may also obtain this information at no cost by calling 1-888-660-6610 or by sending an e-mail request to [email protected]. The Fund's Prospectus and SAI, both dated February 28, 2026, as each may be amended or supplemented, are incorporated by reference into this Summary Prospectus.

Investment Objective

The investment objective of the Vaughan Nelson Emerging Markets Fund (the "Emerging Markets Fund" or "Fund") is to seek long-term capital appreciation.

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.

1 The Fund's advisor has contractually agreed to waive its fees and/or pay for operating expenses of the Fund to ensure that total annual fund operating expenses (excluding any taxes, leverage interest, brokerage commissions, dividend and interest expenses on short sales, acquired fund fees and expenses (as determined in accordance with Form N-1A), professional fees related to services for the collection of foreign tax reclaims, expenses incurred in connection with any merger or reorganization, and extraordinary expenses such as litigation expenses) do not

exceed 1.25% and 1.00% of the average daily net assets of the Investor Class shares and Institutional Class shares, respectively. This agreement is in effect through March 1, 2027, and it may be terminated before that date only by the Trust's Board of Trustees. The Fund's advisor is permitted to seek reimbursement from the Fund, subject to certain limitations, of fees waived or payments made to the Fund for a period ending three full fiscal years after the date of the waiver or payment. This reimbursement may be requested from the Fund if the reimbursement will not cause the Fund's annual expense ratio to exceed the lesser of (a) the expense limitation in effect at the time such fees were waived or payments made, or (b) the expense limitation in effect at the time of the reimbursement.

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual 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. The example reflects the Fund's contractual fee waiver and/or expense reimbursement for the term of the contractual fee waiver and/or expense reimbursement.

Although your actual costs may be higher or lower, based on these assumptions your costs 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 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 most recent fiscal year, the Fund's portfolio turnover rate was 164% of the average value of its portfolio.

Principal Investment Strategies

Under normal circumstances, the Fund will invest at least 80% of its net assets (including amounts borrowed for investment purposes) in equity securities of companies that are either listed, domiciled, or conduct a meaningful amount of business in emerging markets. The Fund's advisor defines companies conducting a meaningful amount of business in emerging markets as those companies that derive at least 50% of revenues or net profits from or have at least 50% of assets or production capacities in, emerging market countries. The Fund's advisor also includes in the definition of emerging market companies those that have been organized under the laws of, have their principal offices or headquarters in, or the securities of which are principally traded in emerging market countries. Emerging market countries are those countries that are considered to be emerging markets or developing economies by the World Bank or the International Finance Corporation or are included in any of Morgan Stanley Capital International ("MSCI") emerging market indices. Emerging market countries are typically located in Asia, Africa, the Caribbean and Central America, South America, Eastern Europe, and the Middle East. The Fund may invest in companies of any market capitalization. From time to time, the Fund may have a significant portion of its assets in one or more market sectors, including the information technology sector.

The Fund's advisor uses a bottom-up approach, employing both fundamental research and quantitative tools, that seeks to identify companies with attractive valuations. The strategy invests in stocks that the Fund's advisor believes are undervalued relative to their intrinsic value over time. The Fund's investments in equity securities may include common stocks, preferred stocks, real estate investment trusts ("REITs") or other trusts, exchange-traded funds ("ETFs"), convertible securities and American, European and Global Depositary Receipts ("ADRs," "EDRs," and "GDRs," respectively). ADRs are receipts that represent interests in foreign securities held on deposit by U.S. banks. EDRs and

GDRs have the same qualities as ADRs, except that they may be traded in several international trading markets. The Fund may also invest in ETFs that invest in portfolios of securities designed to track particular market segments or indices and the shares of which are bought and sold on securities exchanges. The Fund generally will invest in securities of companies located in different countries and regions. From time to time, the Fund may have a significant portion of its assets invested in the securities of companies in one or a few countries or regions.

Principal Risks of Investing

Risk is inherent in all investing and you could lose money by investing in the Fund. A summary description of certain principal risks of investing in the Fund is set forth below. Before you decide whether to invest in the Fund, carefully consider these risk factors associated with investing in the Fund, which may cause investors to lose money. There can be no assurance that the Fund will achieve its investment objective.

Market Risk. The market price of a security or instrument may decline, sometimes rapidly or unpredictably, due to general market conditions that are not specifically related to a particular company, such as real or perceived adverse economic, political or geopolitical conditions throughout the world, changes in the general outlook for corporate earnings, changes in interest or currency rates, or adverse investor sentiment generally.

The market value of a security or instrument also may decline because of factors that affect a particular industry or industries, such as tariffs, labor shortages or increased production costs and competitive conditions within an industry. In addition, local, regional or global events such as war, acts of terrorism, international conflicts, trade disputes, supply chain disruptions, cybersecurity events, the spread of infectious illness or other public health issues, natural disasters or climate events, or other events could have a significant impact on a security or instrument. The increasing interconnectivity between global economies and financial markets increases the likelihood that events or conditions in one region or financial market may adversely impact issuers in a different country, region or financial market.

Equity Risk. The value of the equity securities held by the Fund may fall due to general market and economic conditions, perceptions regarding the industries in which the issuers of securities held by the Fund participate, or factors relating to specific companies in which the Fund invests.

Foreign Investment Risk. The prices of foreign securities may be more volatile than the prices of securities of U.S. issuers because of economic and social conditions abroad, political developments, and changes in the regulatory environments of foreign countries. Changes in exchange rates and interest rates, and the imposition of sanctions, confiscations, trade restrictions (including tariffs) and other government restrictions by the United States and/or other governments may adversely affect the values of the Fund's foreign investments. Foreign companies are generally subject to different legal and accounting standards than U.S. companies, and foreign financial intermediaries may be subject to less supervision and regulation than U.S. financial firms. Foreign securities include ADRs, EDRs and GDRs. Unsponsored ADRs and GDRs are organized independently and without the cooperation of the foreign issuer of the underlying securities, and involve additional risks because U.S. reporting requirements do not apply. In addition, the issuing bank may deduct shareholder distribution, custody, foreign currency exchange, and other fees from the payment of dividends.

Risks Associated with China. The Chinese economy is generally considered an emerging market and can be significantly affected by economic and political conditions and policy in China and surrounding Asian countries. A relatively small number of Chinese companies represent a large portion of China's total market and thus may be more sensitive to adverse political or economic circumstances and market movements. The economy of China differs, often unfavorably, from the U.S. economy in such respects as structure, general development, government involvement, wealth distribution, rate of inflation, growth rate, allocation of resources and capital reinvestment, among others. Under China's political and economic system, the central government has historically exercised substantial control over virtually every sector of the Chinese economy through administrative regulation and/or state ownership. In addition, expropriation, including nationalization, confiscatory taxation, political, economic or social instability or other developments could adversely affect and significantly diminish the values of the Chinese companies in which the Fund invests. International trade tensions may arise from time to time which can result in trade tariffs, embargoes, trade limitations, trade wars and other negative consequences. These consequences may trigger a reduction in international trade, the oversupply of certain manufactured goods, substantial price reductions of goods and possible

failure of individual companies and/or large segments of China's export industry with a potentially severe negative impact to the Fund. From time to time, China has experienced outbreaks of infectious illnesses, and the country may be subject to other public health threats or similar issues in the future. Any spread of an infectious illness, public health threat or similar issue could reduce consumer demand or economic output, result in market closures, travel restrictions or quarantines, and generally have a significant impact on the Chinese economy.

Risks Associated with Taiwan. Investments in Taiwanese issuers involve legal, regulatory, political, currency, and economic risks that are specific to Taiwan. Taiwan's geographic proximity and history of political contention with China have resulted in ongoing tensions between the two countries. These tensions may materially affect the Taiwanese economy and its securities market. Taiwan's economy is export-oriented and depends on open world trade, which makes it vulnerable to fluctuations in the world economy. The Taiwanese economy is dependent on the economies of Asia, mainly those of Japan and China, and the United States. Reduction in spending by any of those countries on Taiwanese products and services, or negative changes in any of those economies, may adversely impact the Taiwanese economy.

Emerging Markets Risk. Many of the risks with respect to foreign investments are more pronounced for investments in issuers in developing or emerging market countries. Emerging market countries tend to have more government exchange controls, more volatile interest and currency exchange rates, less market regulation, and less developed and less stable economic, political and legal systems than those of more developed countries. There may be less publicly available and reliable information about issuers in emerging markets than is available about issuers in more developed markets. In addition, emerging market countries may experience high levels of inflation and may have less liquid securities markets and less efficient trading and settlement systems.

Currency Risk. The values of investments in securities denominated in foreign currencies increase or decrease as the rates of exchange between those currencies and the U.S. dollar change. Currency conversion costs and currency fluctuations could erase investment gains or add to investment losses. Currency exchange rates can be volatile and are affected by factors such as general economic conditions, the actions of the United States and foreign governments or central banks, the imposition of currency controls, and speculation.

Market Capitalization Risk. Larger, more established companies may be unable to attain the high growth rates of successful, smaller companies during periods of economic expansion. The securities of small-capitalization or mid-capitalization companies may be subject to more abrupt or erratic market movements and may have lower trading volumes or more erratic trading than securities of larger, more established companies or market averages in general. In addition, such companies typically are more likely to be adversely affected than large capitalization companies by changes in earning results, business prospects, investor expectations or poor economic or market conditions.

Sector Focus Risk. The Fund may invest a larger portion of its assets in one or more sectors than many other mutual funds, and thus will be more susceptible to negative events affecting those sectors. For example, as of December 31, 2025, 25.82% of the Fund's assets were invested in the information technology sector. Companies in the information technology sector can be significantly affected by intense competition, consumer preferences, problems with product compatibility and government regulation.

Issuer Risk. Issuer-specific attributes may cause a security held by the Fund to be more volatile than the market generally. The prices of, and income generated by, securities held by the Fund may decline in response to various factors directly related to the issuers of such securities, including reduced demand for an issuer's goods or services, poor management performance, major litigation, investigations or other controversies related to the issuer, changes in the issuer's financial condition or credit rating, changes in government regulation affecting the issuer or its competitive environment, and strategic initiatives such as mergers, acquisitions or dispositions and the market response to any such initiatives. An individual security may also be affected by factors related to the industry or sector of the issuer or the securities markets as a whole, and conversely an industry or sector or the securities markets may be affected by a change in financial condition or another event affecting a single issuer. The value of an individual security or particular type of security may be more volatile than the market as a whole and may perform differently from the value of the market as a whole. At times, the Fund may invest more significantly in a single issuer, which could increase the Fund's volatility and the risk of loss arising from the factors described above.

Portfolio Turnover Risk. Active and frequent trading of the Fund's portfolio securities may lead to higher transaction costs and may result in a greater number of taxable transactions than would otherwise be the case, which could negatively affect the Fund's performance. A high rate of portfolio turnover is 100% or more.

ETF Risk. Investing in an ETF will provide the Fund with exposure to the securities comprising the index on which the ETF is based and will expose the Fund to risks similar to those of investing directly in those securities. Shares of ETFs typically trade on securities exchanges and may at times trade at a premium or discount to their net asset values. In addition, an ETF may not replicate exactly the performance of the benchmark index it seeks to track for a number of reasons, including transaction costs incurred by the ETF, the temporary unavailability of certain index securities in the secondary market or discrepancies between the ETF and the index with respect to the weighting of securities or the number of securities held. Investing in ETFs, which are investment companies, involves duplication of advisory fees and certain other expenses. The Fund will pay brokerage commissions in connection with the purchase and sale of shares of ETFs.

REIT Risk. Investing in REITs will subject the Fund to risks similar to those associated with direct ownership of real estate, including losses from casualty or condemnation, and changes in local and general economic conditions, supply and demand, interest rates, zoning laws, regulatory limitations on rents, property taxes and operating expenses.

Management and Strategy Risk. The value of your investment depends on the judgment of the Fund's advisor about the quality, relative yield, value or market trends affecting a particular security, industry, sector or region, which may prove to be incorrect.

Value-Oriented Investment Strategies Risk. Value stocks are those that are believed to be undervalued in comparison to their peers due to adverse business developments or other factors. Value investing is subject to the risk that the market will not recognize a security's inherent value for a long time or at all, or that a stock judged to be undervalued may actually be appropriately priced or overvalued. In addition, during some periods (which may be extensive) value stocks generally may be out of favor in the markets.

Convertible Securities Risk. Convertible securities are subject to market and interest rate risk and credit risk. When the market price of the equity security underlying a convertible security decreases the convertible security tends to trade on the basis of its yield and other fixed income characteristics, and is more susceptible to credit and interest rate risks. When the market price of such equity security rises, the convertible security tends to trade on the basis of its equity conversion features and be more exposed to market risk. Convertible securities are typically issued by smaller capitalized companies with stock prices that may be more volatile than those of other companies.

Preferred Stock Risk. Preferred stock represents an equity interest in a company that generally entitles the holder to receive, in preference to the holders of other stocks such as common stock, dividends and a fixed share of the proceeds resulting from a liquidation of the company. The market value of preferred stock is subject to company-specific and market risks applicable generally to equity securities and is also sensitive to changes in the company's creditworthiness, the ability of the company to make payments on the preferred stock, and changes in interest rates, typically declining in value if interest rates rise.

Recent Market Events. Periods of market volatility may occur in response to market events, public health emergencies, natural disasters or climate events, and other economic, political, and global macro factors. U.S. and international markets have recently experienced, and may continue to experience, periods of significant volatility due to various factors, including uncertainty regarding inflation and central banks' interest rate changes, the possibility of a national or global recession, trade tensions and tariffs, and political and geopolitical events. In addition, wars or threats of war and aggression, such as Russia's invasion of Ukraine and the conflict among nations and militant groups in the Middle East, have led, and in the future may lead, to increased short-term market volatility and may have adverse long-term effects on the U.S. and world economies and markets generally, each of which may negatively impact the Fund's investments. Additionally, since the change in the U.S. presidential administration in 2025, the administration has pursued an aggressive foreign policy agenda, including actual or

potential imposition of tariffs, which may have consequences on the United States' relations with foreign countries, the economy, and markets generally. These and other similar events could be prolonged and could adversely affect the value and liquidity of the Fund's investments, impair the Fund's ability to satisfy redemption requests, and negatively impact the Fund's performance.

Cybersecurity Risk. Cybersecurity incidents may allow an unauthorized party to gain access to Fund assets, customer data (including private shareholder information), or proprietary information, or cause the Fund, the Fund's advisor, and/or other service providers (including custodians, sub-custodians, transfer agents and financial intermediaries) to suffer data breaches, data corruption or loss of operational functionality. In an extreme case, a shareholder's ability to exchange or redeem Fund shares may be affected. The use of artificial intelligence and machine learning could exacerbate these risks. Issuers of securities in which the Fund invests are also subject to cybersecurity risks, and the value of those securities could decline if the issuers experience cybersecurity incidents.

Performance

The bar chart and table below provide an indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year for Institutional Class shares and by showing how the average annual total returns of Institutional Class shares of the Fund compare with the average annual total returns of a the MSCI Emerging Markets Index, a broad-based market index, and the MSCI Emerging Markets SMID Cap Index. Performance for classes other than those shown may vary from the performance shown to the extent the expenses for those classes differ. Prior to March 1, 2024, the Fund was named the Vaughan Nelson Emerging Markets Opportunities Fund and invested primarily in equity securities of small- to mid-capitalization emerging market companies. Updated performance information is available at the Fund's website, https://www.im.natixis.com/us/vaughan-nelson-funds. The Fund's past performance, before and after taxes, is not necessarily an indication of how the Fund will perform in the future. Effective October 1, 2019, Vaughan Nelson Investment Management, L.P. became investment advisor to the Fund. The performance shown for periods prior to October 1, 2019, is that of the Fund's previous advisor, Advisory Research, Inc.

Calendar Year Total Return (before taxes) for Institutional Class Shares
For each calendar year at net asset value per share ("NAV")

* Investor Class shares were first offered on December 2, 2019. The performance figures for Investor Class shares include the performance for the Institutional Class shares for the period prior to December 2, 2019, adjusted for Investor Class shares' expenses, which are higher than the expenses of Institutional Class shares.

** 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 Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Investment Advisor

Vaughan Nelson Investment Management, L.P. ("Vaughan Nelson" or the "Advisor")

Portfolio Managers

Adam C. Rich and Kevin A. Ross are the portfolio managers who have primary responsibility for the day-to-day management of the Fund. Each has served as the Fund's portfolio manager since the year stated below.

Purchase and Sale of Fund Shares

To purchase shares of the Fund, you must invest at least the minimum amount.

Fund shares are redeemable on any business day the New York Stock Exchange (the "NYSE") is open for business by written request or by telephone.

Tax Information

The Fund's distributions are generally taxable, and will ordinarily be taxed as ordinary income, qualified dividend income or capital gains, unless you are investing through a tax-advantaged arrangement, such as a 401(k) plan or an individual retirement account. Shareholders investing through such tax-advantaged arrangements may be taxed later upon withdrawal of monies from those arrangements.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase shares of the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and its related companies may pay the intermediary for the sale of Fund shares and related services. 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.