HORIZON HIGH INCOME ETF

YLDY

Before you invest, you may want to review the Prospectus for the Horizon High Income ETF (as defined below), which contains more information about the Horizon High Income ETF and its risks. The current statutory Prospectus and Statement of Additional Information (“SAI”) dated August 1, 2026, are incorporated by reference into this Summary Prospectus. You can find the Horizon High Income ETF’s Prospectus, SAI, reports to shareholders, and other information about the Horizon High Income ETF online at www.horizonmutualfunds.com. You can also get this information at no cost by calling 1-855-754-7932 or by sending an e-mail request to funds@horizoninvestments.com.

Investment Objective: Horizon High Income ETF (the “High Income Fund” or the “Fund”) seeks current income and capital appreciation.

Fees and Expenses of the High Income Fund

This table describes the fees and expenses that you may pay if you buy, hold and sell shares of the High Income Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.

Example: This Example is intended to help you compare the cost of investing in the High Income Fund with the cost of investing in other funds. The Example assumes that you invest $10,000 in the High Income 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 High Income Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based upon these assumptions your costs would be:

Portfolio Turnover. The High Income 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 High Income Fund’s performance. Because the Fund is newly organized, portfolio turnover information is not yet available.

Principal Investment Strategies of the High Income Fund

The Fund is an actively managed exchange-traded fund (“ETF”) that seeks to achieve its investment objective primarily by: (i) investing in equity securities of U.S. large-capitalization companies (“Equity Strategy”); and (ii) selling options on broad-based securities indices to generate income (“Options Strategy”).

Equity Strategy: As part of the Equity Strategy, the Fund will invest in equity securities of U.S. large-capitalization issuers (those with a market capitalization in excess of $10 billion at the time of purchase, or otherwise within the range of companies in the S&P 500 index). Horizon Investments, LLC, the Fund’s investment adviser (“Horizon”) expects that the Equity Strategy will invest primarily in dividend-paying equity securities (including common and preferred stock, convertible debt

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securities, American Depositary Receipts (“ADRs”), real estate investment trusts (“REITs”)). Horizon considers dividend-paying securities to include securities of issuers that (i) have paid a dividend in the prior 12-calendar months or (ii) are reasonably likely, in Horizon’s view, to pay a dividend within the 12-calendar months following the Fund’s acquisition of the security, as well as other investment companies (primarily other ETFs) that invest primarily in these issuers. While the Fund expects to invest primarily in dividend-paying U.S. large-capitalization issuers, the Fund may invest without restriction as to the issuer’s market capitalization or dividend expectations.

Horizon utilizes a multi-disciplinary approach that combines active management with economic, quantitative, and fundamental analysis (e.g., factors such as growth, value, momentum, quality, size, and volatility) to identify and select, without limitation, securities of issuers that exhibit one or more of the following fundamental characteristics:

In constructing the portfolio, Horizon may consider industry and position constraints to ensure sufficient diversification, as determined by Horizon. The Fund may engage in frequent trading to achieve its objective and, depending on Horizon’s outlook and market conditions, may focus its investments in particular sectors or areas of the economy.

Options: The Fund’s Options Strategy seeks to enhance income and manage portfolio volatility and consists primarily of selling call options on broad-based securities indices (including, without limitation, the S&P 500) or ETFs that track broad-based securities indices. When the Fund sells a call option, the Fund receives a premium from the purchaser of the call option, which grants the purchaser the right to participate in the potential gains of the underlying index above a predetermined strike price until the option’s expiration. If the option is exercised by the buyer, the Fund must pay the difference between the index price and the option’s strike price. Options used by the Fund may be exchange-traded (including FLEX Options) or OTC Options. FLEX Options are customizable exchange-traded option contracts guaranteed for settlement by the Options Clearing Corporation (the “OCC”). Terms that can be customized for FLEX Options include exercise price, exercise styles, and expiration dates.

During periods where the U.S. equity market is relatively stable, falling, or slightly rising such that the option premiums received by the Fund exceed the appreciation of the index above the strike price, the strategy may outperform an otherwise similar strategy that does not generate additional income from option premiums. Alternatively, during periods of rising markets where gains in the underlying indices exceed the premiums received, the strategy would be expected to underperform an otherwise similar strategy with no option overlay. The Fund expects that the underlying portfolio of securities, together with the option overlay, should in the aggregate result in a portfolio with a modest defensive tilt as compared to the S&P 500, designed to outperform in flat to down markets and expected to underperform in large positive markets.

In addition to the sale of call options discussed above, the Fund may also buy or write put and call options on individual securities (including ETFs) or securities indices for investment purposes, to hedge other investments, or to generate additional option premiums for the Fund. The Fund’s option strategies may also involve combinations such as spreads, straddles, and collars. In a “spread” transaction, the Fund buys and writes a put or buys and writes a call on the same underlying instrument with the options having different strike prices, expiration dates, or both. In a “straddle,” the Fund simultaneously buys or writes a put and a call on the same underlying instrument with the same strike price and expiration date. In a “collar,” the Fund holds the underlying instrument while simultaneously buying a put option and writing a call option on that instrument to limit the range of potential gains and losses. The Fund writes covered call options, meaning the Fund holds the underlying security against which the call is written, and may also write cash-secured or otherwise collateralized put options. There is no limit on the number or size of the options transactions in which the Fund may engage, and the amount of the Fund’s portfolio allocated to the options strategy is expected to vary based on Horizon’s market outlook and risk assessment.

The Fund will typically sell portfolio securities to seek to secure gains or limit potential losses when Horizon believes that other more favorable opportunities exist or when Horizon otherwise believes it is in the best interest of the Fund.

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The Fund is classified as non-diversified under the Investment Company Act of 1940, as amended (the “1940 Act”), which means that it may invest a high percentage of its assets in a limited number of issuers.

Principal Risks of the High Income Fund

Many factors affect the High Income Fund’s performance. The High Income Fund is not federally insured or guaranteed by any government agency. You may lose money by investing in the Fund and there is no guarantee that the Fund will achieve its investment objective. The principal risks affecting shareholders’ investments in the Fund are set forth below.

Management Risk. The ability of the Fund to meet its investment objective is directly related to the allocation of the Fund’s assets. Horizon may allocate the Fund’s investments to under-emphasize or over-emphasize investments at the wrong times or under the wrong market conditions, in which case the Fund’s value may be adversely affected.

Market Risk. Investments in securities in general are subject to market risks that may cause their prices to fluctuate over time. The Fund’s investments may decline in value due to factors affecting securities markets generally, or particular countries, segments, economic sectors, industries or companies within those markets. The value of a security may decline due to general economic and market conditions that are not specifically related to a particular issuer. Markets may, in response to governmental actions or intervention, economic or market developments, trade disputes, the spread of infectious illness or other public health issues, geopolitical factors or other external factors, experience periods of high volatility and reduced liquidity, and, in extreme cases, may lead to trading restrictions and halts. These and other similar events could be prolonged and could adversely affect the value and liquidity of the Fund’s investments and negatively impact the Fund’s performance.

Equity Securities Risk. Equity securities typically have greater price volatility than fixed income securities. The market price of equity securities owned by the Fund may go down, sometimes rapidly or unpredictably. Equity securities may decline in value due to factors affecting equity securities markets generally, particular industries represented by those markets, or factors directly related to a specific company, such as decisions made by its management.

Large Capitalization Company Risk. Large capitalization companies as a group could fall out of favor with the market, causing the Fund to underperform investments that focus on small or mid-cap companies.

Smaller and Medium Issuer Risk. Small and medium capitalization companies may be more vulnerable than larger, more established organizations to adverse business or economic developments. In addition, small and medium capitalization companies may be particularly affected by interest rate increases, as they may find it more difficult to borrow money to continue or expand operations, or may have difficulty in repaying any loans.

Investments in Other Investment Companies Risk. The Fund may invest in the securities of other investment companies, such as mutual funds, closed-end funds, business development companies, and ETFs. These investments expose the Fund to the risks of the underlying funds, including the risk that those funds may not achieve their investment objectives or may underperform. The Fund will also bear its proportionate share of fees and expenses of the underlying funds, which may increase overall costs. Regulatory limits may restrict the Fund’s ability to invest in other funds.

REIT Risk. REITs involve risks similar to those associated with direct investments in real estate, including sensitivity to changes in interest rates, property values, and rental income. REITs are also subject to risks related to the management and operation of properties, as well as the risk that the Fund may experience delays or losses if a REIT is liquidated or declares bankruptcy. Additionally, REITs may fail to qualify for favorable tax treatment under the Internal Revenue Code of 1986, as amended (the “Code”), which could adversely affect their value. The Fund will indirectly bear its proportionate share of expenses, including management fees, paid by each REIT in which it invests in addition to the expenses of the Fund. Publicly traded REIT share are also subject to “Equity Securities Risk”.

ADR Risk. ADRs are subject to risks similar to those associated with direct investments in foreign securities, including currency exchange rate fluctuations, political and economic instability, foreign regulatory and accounting standards, and less publicly available information about foreign issuers. ADRs may also be subject to liquidity risks, as trading volumes for ADRs can be lower than those for U.S. securities, which may result in higher volatility or difficulty in buying or selling the securities at an optimal price.

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Dividend Yield Risk. While the Fund may hold securities of companies that have historically paid a dividend, those companies may reduce or discontinue their dividends in the future, thus reducing income to the Fund. Past dividend payments are not a guarantee of future dividend payments. Also, the market return of high dividend yield securities, in certain market conditions, may be worse than the market return of other investment strategies or of markets generally.

Options Risk. Investments in options involve risks different from, or possibly greater than, the risks associated with investing directly in securities, including leverage risk, and tracking risk. Option positions may expire worthless, exposing the Fund to potentially significant losses. If the Fund writes options, it may receive a premium that is small relative to the loss realized in the event of adverse changes in the value of the underlying instruments. When the Fund utilizes options combinations, such as spreads, straddles, collars, or other strategies, the premium received for writing the call option may offset, in part, the premium paid to purchase the corresponding put option; however, these strategies may limit upside gains while not fully protecting against downside risks, and the cost of implementing them may reduce the Fund’s overall returns.

Exchange-Traded Options. Exchange-traded options in the United States are issued by a clearing organization affiliated with the exchange on which the option is listed that, in effect, guarantees completion of every exchange-traded option transaction. FLEX Options are a type of exchange-traded option that are customizable with respect to certain terms, including exercise prices, exercise styles, and expiration dates. FLEX Options are guaranteed for settlement by the Options Clearing Corporation (the “OCC”). Although unlikely, it is possible the OCC is unable to meet its settlement obligations, which could result in substantial loss for the Fund. Upon expiration, the FLEX Options held by the Fund will be exercisable at the strike price. Prior to the expiration date, the value of the FLEX Options will be determined based upon market quotations or using other recognized pricing methods. The value of the FLEX Options prior to the expiration date may vary due to factors other than the value of the underlying asset, such as interest rate changes, changing supply and demand, decreased liquidity of the FLEX Options, a change in the actual and perceived volatility of the stock market and underlying asset, and the remaining time to expiration. A Fund’s ability to establish and close out positions in exchange-traded options depends on the existence of a liquid market. FLEX Options may be less liquid than more traditional exchange-traded option contracts, meaning that the Fund may have more difficulty closing out certain FLEX Options positions at desired times and prices. There can be no assurance that a liquid market will exist at any particular time.

OTC Options. In contrast to exchange-traded options, OTC options are contracts between a Fund and its counterparty (usually a securities dealer or a bank) with no clearing organization guarantee. Thus, when a Fund purchases an OTC option, it relies on the counterparty from which it purchased the option to make or take delivery of the underlying investment upon exercise of the option. Failure by the counterparty to do so would result in the loss of any premium paid by a Fund as well as the loss of any expected benefit of the transaction. Closing transactions for OTC options can be made only by negotiating directly with the counterparty, or by a transaction in the secondary market if any such market exists. There can be no assurance that a Fund will in fact be able to close out an OTC option position at a favorable price prior to expiration. In the event of insolvency of the counterparty, a Fund might be unable to close out an OTC option position at any time prior to its expiration.

Non-Diversification Risk. The Fund is classified as “non-diversified.” This means that, compared with other funds that are classified as “diversified,” the Fund invests a greater percentage of its assets in securities issued by or representing a small number of issuers. As a result, the Fund’s performance may depend on the performance of a small number of issuers.

Sector and Focus Risk. To the extent that the Fund focuses its investments in particular industries, asset classes or sectors of the economy, any market price movements, regulatory or technological changes, or economic conditions affecting companies in those industries, asset classes or sectors may have a significant impact on the Fund’s performance.

Frequent Trading and Portfolio Turnover Risk. The Fund may engage in frequent trading to achieve its investment objectives, which could result in higher transaction costs and taxable gains, negatively impacting performance. As an ETF, the Fund may also experience active trading of its shares in the market, which could lead to more frequent creation or redemption activities. In certain circumstances, this activity could increase the number of portfolio transactions, resulting in high portfolio turnover. High levels of portfolio turnover may increase brokerage and other transaction costs and could lead to increased taxable capital gains. These factors, in combination with the Fund’s pursuit of its investment objectives, could have a negative impact on the Fund’s overall performance.

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ETF Risks. The Fund is an ETF and invests in other ETFs. As result of this structure, the Fund is exposed directly or indirectly to the following risks:

Authorized Participants, Market Makers, and Liquidity Providers Concentration Risk. Only an Authorized Participant (an “Authorized Participant” or an “AP”) may engage in creation and redemption transactions directly with an ETF. An ETF has a limited number of financial institutions that may act as Authorized Participants. In addition, there may be a limited number of market makers and/or liquidity providers in the marketplace. To the extent that: (i) APs exit the business or otherwise become unable to process creation and/or redemption orders and no other APs step forward to perform these services; or (ii) market makers and/or liquidity providers exit the business or significantly reduce their business activities and no other entities step forward to perform such functions, ETF shares may trade at a material discount to NAV, the bid-ask spread could widen, and shares could face trading halts and/or delisting.

Costs of Buying or Selling Shares. Investors buying or selling ETF shares in the secondary market will pay brokerage commissions or other charges imposed by brokers as determined by those brokers. Brokerage commissions are often a fixed amount and may be a significant proportional cost for investors seeking to buy or sell relatively small amounts of Shares. In addition, secondary market investors will also incur the cost of the difference between the price that an investor is willing to pay for an ETF’s shares (the “bid” price) and the price at which an investor is willing to sell the ETF’s shares (the “ask” price). This difference in bid and ask prices is often referred to as the “spread” or “bid/ask spread”. The bid/ask spread varies over time for an ETF’s shares based on trading volume and market liquidity and is generally lower if an ETF’s shares have more trading volume and market liquidity and higher if the ETF’s shares have little trading volume and market liquidity. Further, increased market volatility may cause increased bid/ask spreads. Due to the costs of buying or selling ETF shares, including bid/ask spreads, frequent trading of an ETF’s shares may significantly reduce investment results and an investment in an ETF’s shares may not be advisable for investors who anticipate regularly making small investments.

Shares May Trade at Prices Other Than NAV. ETF shares may be bought and sold in the secondary market at market prices. The market prices of the shares will generally fluctuate in accordance with changes in NAV as well as the relative supply of and demand for the shares on the Exchange and there may be times when the market price of an ETF’s shares is more than the NAV intra-day (premium) or less than the NAV intra-day (discount) due to supply and demand of the ETF’s shares or during periods of market volatility. If an investor buys ETF shares when the shares’ market price is at a premium, the investor may pay more than the shares’ underlying value. If an investor sells ETF shares when the shares’ market price is at a discount, the investor may receive less than the shares’ underlying value. This risk is heightened in times of market volatility, periods of steep market declines, and periods when there is limited trading activity for the ETF shares in the secondary market, in which case such premiums or discounts may be significant.

Trading. Although Fund shares are listed for trading on Cboe BZX Exchange, Inc. (the “Exchange”) and may be traded on U.S. exchanges other than the Exchange, there can be no assurance that an active trading market will develop or be maintained for Fund shares or that Fund shares will trade with any volume, or at all, on any stock exchange. In stressed market conditions, the liquidity of ETF shares may begin to mirror the liquidity of the ETF’s underlying portfolio holdings, which can be significantly less liquid than the ETF’s shares and could lead to differences between the market price of the ETF’s shares and the underlying value of those shares. These conditions could cause an ETF’s shares to trade at a material discount to NAV and the bid-ask spread to widen.

Trading Issues. Trading in shares on an exchange may be halted due to market conditions or for reasons that, in the view of the exchange, make trading in shares inadvisable. In addition, trading in shares on an exchange is subject to trading halts caused by extraordinary market volatility pursuant to the exchange’s “circuit breaker” rules. There can be no assurance that the requirements of an exchange necessary to maintain the listing of tan ETF will continue to be met or will remain unchanged. Shares of an ETF, similar to shares of other issuers listed on a stock exchange, may be sold short and are therefore subject to the risk of increased volatility and price decreases associated with being sold short.

Quantitative Model Risk. The Fund’s strategy relies heavily on quantitative models and the analysis of specific metrics to construct the Fund’s portfolio. The impact of these metrics on a stock’s performance can be difficult to predict, and stocks that previously possessed certain desirable quantitative characteristics may not continue to demonstrate

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those same characteristics in the future. In addition, relying on quantitative models entails the risk that the models themselves may be limited or incorrect, that the data on which the models rely may be incorrect or incomplete, and that Horizon may not be successful in selecting companies for investment or determining the weighting of particular stocks in the Fund’s portfolio. Any of these factors could cause the Fund to underperform funds with similar strategies that do not select stocks based on quantitative analysis.

Domestic Strategy Risk. Because the Fund will invest primarily in securities of U.S. issuers, the Fund is subject to the risk that certain changes in the U.S. economy, such as when the U.S. economy weakens or when its financial markets decline, may have an adverse effect on the securities to which the Fund has exposure, and the Fund will be restricted in its ability to allocate its investments to the securities of non-U.S. issuers.

Operational and Technology Risk. Cyber-attacks, disruptions, or failures that affect the Fund’s service providers or counterparties, issuers of securities held by the Fund, or other market participants may adversely affect the Fund and its shareholders, including by causing losses for the Fund or impairing its operations.

New Fund Risk. The Fund is recently organized and has limited operating history as of the date of this Prospectus. There can be no assurance that the Fund will grow to or maintain an economically viable size.

Performance

The Fund is new and therefore does not have performance history for a full calendar year. Once the Fund has completed a full calendar year of operations, a bar chart and table will be included that will provide some indication of the risks of investing in the Fund by showing the variability of the Fund’s returns and comparing the Fund’s performance to a broad measure of market performance. Updated performance information is available at no cost by visiting www.horizonmutualfunds.com or by calling 1-855-754-7932.

Investment Adviser. Horizon Investments, LLC

Sub-Adviser: Exchange Traded Concepts, LLC.

Portfolio Managers. Scott Ladner, Chief Investment Officer of Horizon, Mike Dickson, Ph.D., Head of Research and Quantitative Strategies of Horizon, Zachary F. Hill, CFA, Head of Portfolio Management of Horizon, and Clark Allen, Head of ETFs of Horizon, share responsibility for the day-to-day management of the High Income Fund as Co-Portfolio Managers and have each been a Co-Portfolio Manager of the High Income Fund since inception.

Purchase and Sale of Fund Shares. Individual shares may only be purchased and sold on a national securities exchange through a broker-dealer. You can purchase and sell individual shares of the Fund throughout the trading day like any publicly traded security. The Fund’s shares are listed on the Exchange. The price of the Fund’s shares is based on market price and, because exchange-traded fund shares trade at market prices rather than NAV, shares may trade at a price greater than NAV (premium) or less than NAV (discount). The Fund issues and redeems shares on a continuous basis, at NAV, only in blocks of shares called Creation Units, principally in-kind, and only Authorized Participants (typically, broker-dealers) may purchase or redeem Creation Units. When buying or selling the Fund’s shares on Exchange, 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”). Recent information regarding the Fund’s NAV, market price, premiums and discounts, and bid-ask spreads is available at www.horizonmutualfunds.com.

Tax Information

The Fund’s distributions are taxed as ordinary income or capital gains, unless you are investing through a tax- deferred arrangement, such as a 401(k) plan or an individual retirement account (“IRA”). Such tax-deferred arrangements may be taxed later upon withdrawal of monies from those arrangements.

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