The information in this Prospectus is not complete and may be changed. We may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This Prospectus is not an offer to sell these securities and it is not soliciting an offer to buy these securities in any state where the offer of sale is not permitted.

Subject to Completion
May 20, 2026

PROSPECTUS

Roundhill Photonics & Optics ETF (LYTE)

_____, 2026

Roundhill Photonics & Optics ETF (the “Fund”) is a series of Roundhill ETF Trust (the “Trust”) and an exchange-traded fund (“ETF”). The Fund lists and principally trades its shares on the [___] (the “Exchange”).

The U.S. Securities and Exchange Commission (“SEC”) has not approved or disapproved these securities or passed upon the accuracy or adequacy of this prospectus. Any representation to the contrary is a criminal offense.

Table of Contents

Summary Information	1
Additional Information About the Fund’s Principal Investment Strategies	13
Additional Risks of Investing in the Fund	14
Management of the Fund	23
How to Buy and Sell Shares	26
Dividends, Distributions and Taxes	27
Distributor	30
Net Asset Value	30
Fund Service Providers	31
Premium/Discount Information	31
Investments by Other Investment Companies	31
Financial Highlights	31

Roundhill Photonics & Optics ETF

Investment Objective

The Fund seeks to provide capital appreciation.

Fees and Expenses of the Fund

The table below describes the fees and expenses that you may pay if you buy, hold and sell shares of the Fund (“Fund Shares”). 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⁽¹⁾	0.[__]%
Distribution and Service (12b-1) Fees	0.00%
Other Expenses⁽²⁾	0.00%
Total Annual Fund Operating Expenses	0.[__]%

(1) The investment advisory agreement between the Trust and Roundhill Financial Inc. (“Roundhill”) utilizes a unitary fee arrangement pursuant to which Roundhill will pay all operating expenses of the Fund, except Roundhill’s management fees, interest charges on any borrowings, dividends and other expenses on securities sold short, taxes, brokerage commissions and other expenses incurred in placing orders for the purchase and sale of securities and other investment instruments, acquired fund fees and expenses, accrued deferred tax liability, extraordinary expenses, and distribution fees and expenses paid by the Trust under any distribution plan.

(2) “Other Expenses” are estimates based on the expenses the Fund expects to incur for the current fiscal year.

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your Fund 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. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Year 1	Year 3
$[___]	$[___]

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. Because the Fund has not yet commenced operations, portfolio turnover information is unavailable at this time.

Principal Investment Strategies

The Fund is an actively managed exchange-traded fund (“ETF”) that seeks to achieve its investment objective by investing in the equity securities of companies whose core technology involves generating, manipulating, detecting, or transmitting light for various technologies, such as AI data centers, defense, medical imaging, industrial manufacturing, and quantum computing (“Photonic and Optical Companies”).

Under normal circumstances, the Fund invests at least 80% of its net assets (plus borrowings for investment purposes) in equity securities (which may include depositary receipts) or financial instruments (i.e., swap agreements or forward contracts) that provide exposure to Photonic and Optical Companies. For purposes of compliance with this investment policy, derivative contracts (i.e., swap agreements and forward contracts) will be valued at their notional value.

The Fund’s adviser, Roundhill Financial Inc. (“Roundhill” or the “Adviser”), identifies for potential investment Photonic and Optical Companies with at least 50% of their revenues attributable to the research, development, manufacturing, or sale of one or more of the following optical and/or photonic technologies:

• Optical transceivers and modules,

• Laser sources and photonic components,

• Silicon photonics (“SiPh”) integrated circuits,

• Optical interconnect systems,

• Photonic substrates and wafer materials,

• Photonic foundry and contract manufacturing services,

• Industrial and defense lasers,

• Precision photodetectors, sensors, and imaging systems,

• Fiber optic cable and connectivity infrastructure,

• Optical computing and photonic AI acceleration, and

• Related technologies in photonics and/or optics.

In seeking to achieve the Fund’s investment objective, the Adviser constructs the portfolio using its proprietary security selection methodology. The Adviser generally invests in Photonic and Optical Companies it believes are leaders in optical and/or photonic products and related technologies, considering factors such as market share and revenue share derived from the sales or production of such products.

The Fund will seek to invest in those companies with a minimum market capitalization of $[__] and an average daily trading volume of at least $[__]. The Fund may invest in U.S. and non-U.S. companies (including those operating in developed or emerging market countries) through investments in depositary receipts, American Depositary Receipts (“ADRs”) or Global Depositary Receipts (“GDRs”), including depositary receipts whose underlying securities are non-voting preferred securities. Such companies may be small-, mid- or large-capitalization issuers. The Fund rebalances its portfolio at least quarterly using the Adviser’s proprietary weighting methodology. The Fund does not actively trade securities between rebalances.

Certain of the ADRs to which the Fund will have investment exposure may be structured as variable interest entities or “VIEs.” A VIE is a special structure designed to provide foreign investors with exposure to Chinese companies. Investments in VIEs come with additional risks that are described in the section entitled “Principal Risks.” The Fund may derive investment exposure to Chinese companies through investments in China A-Shares. China A-Shares represent equity securities of companies incorporated in mainland China, traded on the Shanghai and Shenzhen stock exchanges.

The Fund will concentrate (i.e., invest more than 25% of its total assets) its investments in the group of industries comprising the information technology sector.

The Fund is classified as “non-diversified” under the Investment Company Act of 1940 (the “1940 Act”).

Principal Risks

As with all investments, there are certain risks of investing in the Fund. Fund Shares will change in value, and you could lose money by investing in the Fund. An investment in the Fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

PHOTONIC AND OPTICAL COMPANIES RISK. Photonic and Optical Companies may be subject to rapid changes in technology, intense competition, government regulation, and obsolescence risk. Securities of such companies may be subject to greater price volatility than securities of companies in other sectors, particularly over the short term. The prices of securities of companies in these industries may fluctuate widely due to competitive pressures, rapid product cycles, changes in the regulatory environment, and shifts in supply and demand dynamics. Many Photonic and Optical Companies are relatively small and may have limited product lines, markets, financial resources, or personnel, making them more susceptible to business risks and adverse developments. Photonic and Optical Companies may also be dependent upon government contracts or subsidies, which may be subject to cancellation, renegotiation, or delay in payment. Additionally, the development and commercialization of photonic and optical technologies may be contingent upon the broader adoption of related technologies, including artificial intelligence, data center infrastructure, and advanced telecommunications networks. A slowdown or disruption in the growth of these related sectors could materially and adversely affect the revenues and profitability of Photonic and Optical Companies in which the Fund invests.

Market Risk. Market risk is the risk that a particular investment, or Fund Shares in general, may fall in value. Securities are subject to market fluctuations caused by real or perceived adverse economic, political, and regulatory factors or market developments, changes in interest rates, disruptions to trade, impositions of tariffs and perceived trends in securities prices. Fund Shares could decline in value or underperform other investments. In addition, local, regional or global events such as war, acts of terrorism, market manipulation, government defaults, government shutdowns, regulatory actions, political changes, diplomatic developments, the imposition of sanctions and other similar measures, spread of infectious diseases or other public health issues, recessions, natural disasters, or other events could have a significant negative impact on the Fund and its investments. Any of such circumstances could have a materially negative impact on the value of Fund Shares, the liquidity of an investment, and may result in increased market volatility. During any such events, Fund Shares may trade at increased premiums or discounts to their net asset value, the bid/ask spread on Fund Shares may widen and the returns on investment may fluctuate.

LINE OF BUSINESS RISK. Certain companies included in the Fund’s portfolio will be engaged in other lines of business unrelated to the development of optical and/or photonic products, and these lines of business could adversely affect their operating results. The operating results of these companies may fluctuate as a result of these additional risks and events in the other lines of business. Despite a company’s possible success in activities linked to its development of optical and/or photonic products, there can be no assurance that the other lines of business in which these companies are engaged will not have an adverse effect on a company’s business or financial condition.

EQUITY SECURITIES RISK. Equity securities are subject to changes in value, and their values may be more volatile than those of other asset classes. Equity securities prices fluctuate for several reasons, including changes in investors’ perceptions of the financial condition of an issuer or the general condition of the relevant equity market, such as market volatility, or when political or economic events affecting an issuer occur. Common stock prices may be particularly sensitive to rising interest rates, as the cost of capital rises and borrowing costs increase. Common stocks generally subject their holders to more risks than preferred stocks and debt securities because common stockholders’ claims are subordinated to those of holders of preferred stocks and debt securities upon the bankruptcy of the issuer.

ACTIVE MANAGEMENT RISK. The Fund is actively-managed and its performance reflects investment decisions that the Adviser and/or Sub-Adviser makes for the Fund. Such judgments about the Fund’s investments may prove to be incorrect. If the investments selected and the strategies employed by the Fund fail to produce the intended results, the Fund could underperform as compared to other funds with similar investment objectives and/or strategies, or could have negative returns.

ASIA RISK. The Fund invests significantly in the securities of Asian issuers. As such, the Fund is subject to certain risks specifically associated with investments in the securities of Asian issuers. Many Asian economies have experienced rapid growth and industrialization, and there is no assurance that this growth rate will be maintained. Some Asian economies are highly dependent on trade, and economic conditions in other countries within and outside Asia can impact these economies. Certain of these economies may be adversely affected by trade or policy disputes with its major trade partners. There is also a high concentration of market capitalization and trading volume in a small number of issuers representing a limited number of industries, as well as a high concentration of investors and financial intermediaries. Certain Asian countries have experienced and may in the future experience expropriation and nationalization of assets, confiscatory taxation, currency manipulation, political instability, armed conflict and social instability as a result of religious, ethnic, socio-economic and/or political unrest. In particular, escalated tensions involving North Korea and any outbreak of hostilities involving North Korea could have a severe adverse effect on Asian economies. Governments of certain Asian countries have exercised, and continue to exercise, substantial influence over many aspects of the private sector. In certain cases, the government owns or controls many companies, including the largest in the country. Accordingly, government actions could have a significant effect on the issuers of the Fund’s securities or on economic conditions generally. Recent developments in relations between the U.S. and China have heightened concerns of increased tariffs and restrictions on trade between the two countries. An increase in tariffs or trade restrictions, or even the threat of such developments, could lead to a significant reduction in international trade, which could have a negative impact on the economy of Asian countries and a commensurately negative impact on the Fund.

China Risk. The Fund may invest in instruments that provide exposure to Chinese companies, including through investments in China A-Shares, which would subject the Fund to risks specific to China. China may be subject to considerable degrees of economic, political and social instability. China is an emerging market and demonstrates significantly higher volatility from time to time in comparison to developed markets. Over the last few decades, the Chinese government has undertaken reform of economic and market practices and has expanded the sphere of private ownership of property in China. However, Chinese markets generally continue to experience inefficiency, volatility and pricing anomalies resulting from governmental influence, a lack of publicly available information and/or political and social instability.

Chinese companies are also subject to the risk that Chinese authorities can intervene in their operations and structure. Internal social unrest or confrontations with neighboring countries, including military conflicts in response to such events, may also disrupt economic development in China and result in a greater risk of currency fluctuations, currency non-convertibility, interest rate fluctuations and higher rates of inflation.

China has experienced security concerns, such as terrorism and strained international relations. Additionally, China is alleged to have participated in state-sponsored cyberattacks against foreign companies and foreign governments. Actual and threatened responses to such activity and strained international relations, including purchasing restrictions, sanctions, tariffs or cyberattacks on the Chinese government or Chinese companies, may impact China’s economy and Chinese issuers of securities in which the Fund invests. Incidents involving China’s or the region’s security may cause uncertainty in Chinese markets and may adversely affect the Chinese economy and the Fund’s investments. Export growth continues to be a major driver of China’s rapid economic growth. Reduction in spending on Chinese products and services, supply chain diversification, institution of additional tariffs or other trade barriers (including as a result of heightened trade tensions or a trade war between China and the U.S. or in response to actual or alleged Chinese cyber activity) or a downturn in any of the economies of China’s key trading partners may have an adverse impact on the Chinese economy. The Fund’s portfolio may include companies that are subject to economic or trade restrictions (but not investment restrictions) imposed by the U.S. or other governments due to national security, human rights or other concerns of such government. So long as these restrictions do not include restrictions on investments, the Fund is generally expected to invest in such companies.

Chinese companies are not subject to the same degree of regulatory requirements, accounting standards or auditor oversight as companies in more developed countries. As a result, information about the Chinese securities in which the Fund invests may be less reliable or complete. Chinese companies with securities listed on U.S. exchanges may be delisted if they do not meet U.S. accounting standards and auditor oversight requirements, which would significantly decrease the liquidity and value of the securities. There may be significant obstacles to obtaining information necessary for investigations into or litigation against Chinese companies, and shareholders may have limited legal remedies. Chinese companies may also be subject to significantly weaker recordkeeping requirements than the requirements imposed upon U.S. companies.

Asset Class Risk. Securities and other assets in the Fund’s portfolio may underperform in comparison to the general financial markets, a particular financial market or other asset classes.

Concentration Risk. The Fund is concentrated in the industry or group of industries comprising the information technology sector. The Fund may be susceptible to an increased risk of loss, including losses due to adverse events that affect the Fund’s investments more than the market as a whole, to the extent that the Fund’s investments are concentrated in the securities and/or other assets of a particular issuer or issuers, country, group of countries, region, market, industry, group of industries, sector, market segment or asset class.

CURRENT MARKET CONDITIONS RISK. Current market conditions risk is the risk that a particular investment, or Fund Shares in general, may fall in value due to current market conditions. As a means to fight inflation, which remains at elevated levels, the Federal Reserve and certain foreign central banks have raised interest rates; however, the Federal Reserve has recently lowered interest rates and may continue to do so. U.S. regulators have proposed several changes to market and issuer regulations which would directly impact the Fund, and any regulatory changes could adversely impact the Fund’s ability to achieve its investment strategies or make certain investments. Recent and potential future bank failures could result in disruption to the broader banking industry or markets generally and reduce confidence in financial institutions and the economy as a whole, which may also heighten market volatility and reduce liquidity. Additionally, challenges in commercial real estate markets, including rising interest rates, declining valuations and increasing vacancies, could have a broader impact on financial markets. The ongoing adversarial political climate in the United States, as well as political and diplomatic events both domestic and abroad, have and may continue to have an adverse impact the U.S. regulatory landscape, markets and investor behavior, which could have a negative impact on the Fund’s investments and operations. The change in administration resulting from the 2024 United States national elections could result in significant impacts to international trade relations, tax and immigration policies, and other aspects of the national and international political and financial landscape, which could affect, among other things, inflation and the securities markets generally. Other unexpected political, regulatory and diplomatic events within the U.S. and abroad may affect investor and consumer confidence and may adversely impact financial markets and the broader economy. For example, ongoing armed conflicts between Russia and Ukraine in Europe and among Israel, Iran, Hamas and other militant groups in the Middle East, have caused and could continue to cause significant market disruptions and volatility within the markets in Russia, Europe, the Middle East and the United States. The hostilities and sanctions resulting from those hostilities have and could continue to have a significant impact on certain Fund investments as well as Fund performance and liquidity. The economies of the United States and its trading partners, as well as the financial markets generally, may be adversely impacted by trade disputes, including the imposition of tariffs, and other matters. For example, the United States has imposed trade barriers and restrictions on China. In addition, the Chinese government is engaged in a longstanding dispute with Taiwan, continually threatening an invasion. If the political climate between the United States and China does not improve or continues to deteriorate, if China were to attempt invading Taiwan, or if other geopolitical conflicts develop or worsen, economies, markets and individual securities may be adversely affected, and the value of the Fund’s assets may go down. A public health crisis and the ensuing policies enacted by governments and central banks may cause significant volatility and uncertainty in global financial markets, negatively impacting global growth prospects. As the COVID-19 global pandemic illustrated, such events may affect certain geographic regions, countries, sectors and industries more significantly than others. Advancements in technology may also adversely impact markets and the overall performance of the Fund. For instance, the economy may be significantly impacted by the advanced development and increased regulation of artificial intelligence. Additionally, cyber security breaches of both government and non-government entities could have negative impacts

on infrastructure and the ability of such entities, including the Fund, to operate properly. These events, and any other future events, may adversely affect the prices and liquidity of the Fund’s portfolio investments and could result in disruptions in the trading markets.

Cybersecurity Risk. Failures or breaches of the electronic systems of the Fund, the Fund’s adviser, sub-adviser, distributor, and other service providers, market makers, Authorized Participants or the issuers of securities in which the Fund invests have the ability to cause disruptions, negatively impact the Fund’s business operations and/or potentially result in financial losses to the Fund and its shareholders. While the Fund has established business continuity plans and risk management systems seeking to address system breaches or failures, there are inherent limitations in such plans and systems. Furthermore, the Fund cannot control the cybersecurity plans and systems of the Fund’s other service providers, market makers, Authorized Participants or issuers of securities in which the Fund invests.

DEPOSITARY RECEIPTS RISK. Depositary receipts may be less liquid than the underlying shares in their primary trading market. Any distributions paid to the holders of depositary receipts are usually subject to a fee charged by the depositary. Holders of depositary receipts may have limited voting rights, and investment restrictions in certain countries may adversely impact the value of depositary receipts because such restrictions may limit the ability to convert the equity shares into depositary receipts and vice versa. Such restrictions may cause the equity shares of the underlying issuer to trade at a discount or premium to the market price of the depositary receipts.

DERIVATIVES RISK. The use of derivative instruments (i.e., swap agreements and forward contracts) involves risks different from, or possibly greater than, the risks associated with investing directly in securities and other traditional investments. These risks include: (i) the risk that the counterparty to a derivative transaction may not fulfill its contractual obligations; (ii) risk of mispricing or improper valuation; and (iii) the risk that changes in the value of the derivative may not correlate perfectly with the underlying asset. Derivative prices are highly volatile and may fluctuate substantially during a short period of time. Such prices are influenced by numerous factors that affect the markets, including, but not limited to: changing supply and demand relationships; government programs and policies; national and international political and economic events, changes in interest rates, inflation and deflation and changes in supply and demand relationships. Trading derivative instruments involves risks different from, or possibly greater than, the risks associated with investing directly in securities. Derivative contracts ordinarily have leverage inherent in their terms. The use of leverage may cause the Fund to liquidate portfolio positions when it would not be advantageous to do so in order to satisfy its obligations or to meet regulatory or contractual requirements for derivatives. The use of derivatives can magnify potential for gain or loss and, therefore, amplify the effects of market volatility on the Fund Share price.

EMERGING MARKETS RISK. The Fund’s investments in emerging markets may be subject to a greater risk of loss than investments in more developed markets. Emerging markets may be more likely to experience inflation, political turmoil and rapid changes in economic conditions than more developed markets. Emerging markets often have less uniformity in accounting and reporting requirements, unreliable securities valuation and greater risk associated with custody of securities.

not standardized or traded on exchanges. The market for forward contracts is substantially unregulated and can experience lengthy periods of illiquidity, unusually high trading volume and other negative impacts, such as political intervention, which may result in volatility or disruptions in such markets. A relatively small price movement in a forward contract may result in substantial losses to the Fund, exceeding the amount of the margin paid.

INFORMATION TECHNOLOGY COMPANIES RISK. Information technology companies face intense competition, both domestically and internationally, which may have an adverse effect on profit margins. Like other technology companies, information technology companies may have limited product lines, markets, financial resources or personnel. The products of information technology companies may face obsolescence due to rapid technological developments, frequent new product introduction, unpredictable changes in growth rates and competition for the services of qualified personnel. Companies in the information technology sector are heavily dependent on patent and intellectual property rights. The loss or impairment of these rights may adversely affect the profitability of these companies. Information technology companies are facing increased government and regulatory scrutiny and may be subject to adverse government or regulatory action.

International Closed Market Trading Risk. To the extent securities held by the Fund trade on non-U.S. exchanges that are closed when the Fund’s primary listing exchange is open, there are likely to be deviations between the current price of an underlying security and the last quoted price for the underlying security (i.e., the Fund’s quote from the closed foreign market) used for purposes of calculating the Fund’s NAV, resulting in premiums or discounts to the Fund’s NAV and bid/ask spreads that may be greater than those experienced by other funds. In addition, shareholders may not be able to purchase and sell shares of the Fund on days when the NAV of the Fund could be significantly affected by events in the relevant foreign markets (e.g., market holidays, market trading halts or significant volatility in foreign markets).

ISSUER RISK. The performance of the Fund depends on the performance of individual securities to which the Fund has exposure. Changes in the financial condition or credit rating of an issuer of those securities may cause the value of the securities to decline. There is no guarantee that an issuer that paid dividends in the past will continue to do so in the future or will continue paying dividends at the same level.

Large-Capitalization Companies Risk. Large capitalization companies may be less able than smaller capitalization companies to adapt to changing market conditions. Large capitalization companies may be more mature and subject to more limited growth potential compared with smaller capitalization companies. During different market cycles, the performance of large capitalization companies has trailed the overall performance of the broader securities markets.

MID-CAPITALIZATION COMPANIES RISK. Mid-capitalization companies may be more vulnerable to adverse general market or economic developments, and their securities may be less liquid and may experience greater price volatility than larger, more established companies as a result of several factors, including limited trading volumes, fewer products or financial resources, management inexperience and less publicly available information. Accordingly, such companies are generally subject to greater market risk than larger, more established companies.

New Fund Risk. The Fund is a recently organized investment company with a limited operating history. As a result, prospective investors have a limited track record or history on which to base their investment decision.

Non-Diversification Risk. As a “non-diversified” fund, the Fund may hold a smaller number of portfolio securities than many other funds. To the extent the Fund invests in a relatively small number of issuers, a decline in the market value of a particular security held by the Fund may affect its value more than if it invested in a larger number of issuers. The value of the Fund Shares may be more volatile than the values of shares of more diversified funds.

NON-U.S. SECURITIES RISK. Non-U.S. securities are subject to higher volatility than securities of domestic issuers due to possible adverse political, social or economic developments, restrictions on foreign investment or exchange of securities, capital controls, lack of liquidity, currency exchange rates, excessive taxation, government seizure of assets, the imposition of sanctions by foreign governments, different legal or accounting standards, and less government supervision and regulation of securities exchanges in foreign countries.

Operational Risk. The Fund is subject to risks arising from various operational factors, including, but not limited to, human error, processing and communication errors, errors of the Fund’s service providers, counterparties or other third-parties, failed or inadequate processes and technology or systems failures. The Fund relies on third-parties for a range of services, including custody. Any delay or failure relating to engaging or maintaining such service providers may affect the Fund’s ability to meet its investment objective. Although the Fund and the Adviser seek to reduce these operational risks through controls and procedures, there is no way to completely protect against such risks.

PREFERRED SECURITIES RISK. The Fund may invest significantly in depositary receipts whose underlying securities are non-voting preferred securities. Preferred securities combine some of the characteristics of both common stocks and bonds. Preferred securities are typically subordinated to bonds and other debt securities in a company’s capital structure in terms of priority to corporate income, subjecting them to greater credit risk than those debt securities. Generally, holders of preferred securities have no voting rights with respect to the issuing company unless preferred dividends have been in arrears for a specified number of periods, at which time the preferred security holders may obtain limited rights. In certain circumstances, an issuer of preferred securities may defer payment on the securities and, in some cases, redeem the securities prior to a specified date. Preferred securities may also be substantially less liquid than other securities, including common stock.

SMALL-CAPITALIZATION COMPANIES RISK. Small-capitalization companies may be more vulnerable to adverse general market or economic developments, and their securities may be less liquid and may experience greater price volatility than large- and mid-capitalization companies as a result of several factors, including limited trading volumes, fewer products or financial resources, management inexperience and less publicly available information. Accordingly, such companies are generally subject to greater market risk than large- and mid-capitalization companies.

Structural ETF Risks. The Fund is an ETF. Accordingly, it is subject to certain risks associated with its unique structure.

Cash Transactions Risk. The Fund may effect a portion of its creations and redemptions for cash, rather than in-kind securities. Paying redemption proceeds in cash rather than through in-kind delivery of portfolio securities may require the Fund to dispose of or sell portfolio securities or other assets at an inopportune time to obtain the cash needed to meet redemption orders. This may cause the Fund to sell a security and recognize a capital gain or loss that might not have been incurred if it had made a redemption in-kind. As a result, the Fund may pay out higher or lower annual capital gains distributions than ETFs that redeem in-kind. The use of cash creations and redemptions may also cause the Fund Shares to trade in the market at greater bid-ask spreads or greater premiums or discounts to the Fund’s NAV. Furthermore, the Fund may not be able to execute cash transactions for creation and redemption purposes at the same price used to determine the Fund’s NAV. To the extent that the maximum additional charge for creation or redemption transactions is insufficient to cover the execution shortfall, the Fund’s performance could be negatively impacted.

Active Market Risk. Although Fund Shares are listed for trading on the Exchange, there can be no assurance that an active trading market for Fund Shares will develop or be maintained. Fund Shares trade on the Exchange at market prices that may be below, at or above the Fund’s net asset value. Securities, including Fund Shares, are subject to market fluctuations and liquidity constraints that may be caused by such factors as economic, political, or regulatory developments, changes in interest rates, and/or perceived trends in securities prices. Fund Shares could decline in value or underperform other investments.

Market Participants Risk. Only an Authorized Participant may engage in creation or redemption transactions directly with the Fund, and none of those Authorized Participants is obligated to engage in creation and/or redemption transactions. The Fund has a limited number of institutions that may act as Authorized Participants on an agency basis (i.e., on behalf of other market participants). To the extent that Authorized Participants exit the business or are unable to proceed with creation or redemption orders with respect to the Fund and no other Authorized Participant is able to step forward to create or redeem, Fund Shares may be more likely to trade at a premium or discount to NAV and possibly face trading halts or delisting. The Fund may also rely on a small number of third-party market makers to provide a market for the purchase and sale of Fund Shares but such market makers are under no obligation to do so. Decisions by Authorized Participants or market makers to reduce their role or step away from these activities in times of market stress could inhibit the effectiveness of the arbitrage process in maintaining the relationship between the underlying values of the Fund’s portfolio securities and the Fund’s market price. Any trading halt or other problem relating to the trading activity of these market makers or any issues disrupting the Authorized Participants’ ability to proceed with creation and/or redemption orders could result in a dramatic change in the spread between the Fund’s net asset value and the price at which Fund Shares are trading on the Exchange, which could result in a decrease in value of Fund Shares. This reduced effectiveness could result in Fund Shares trading at a premium or discount to net asset value and also in greater than normal intraday bid-ask spreads Fund Shares.

Costs of Buying and Selling Fund Shares. Due to the costs of buying or selling Fund Shares, including brokerage commissions imposed by brokers and bid/ask spreads, frequent trading of

Fund Shares may significantly reduce investment results and an investment in Fund Shares may not be advisable for investors who anticipate regularly making small investments.

Premium/Discount Risk. As with all ETFs, Fund Shares may be bought and sold in the secondary market at market prices. The trading prices of Fund Shares in the secondary market may differ from the Fund’s daily net asset value per share and there may be times when the market price of the shares is more than the net asset value per share (premium) or less than the net asset value per share (discount). If a shareholder purchases Fund Shares at a time when the market price is at a premium to the net asset value or sells Fund Shares at a time when the market price is at a discount to the net asset value, the shareholder may pay more for, or receive less than, the underlying value of the Fund Shares, respectively. This risk is heightened in times of market volatility or periods of steep market declines.

Trading Risks. Although Fund Shares are listed for trading on the Exchange and may be traded on U.S. exchanges other than the Exchange, there can be no assurance that Fund Shares will trade with any volume, or at all, on any stock exchange. In stressed market conditions, the liquidity of Fund Shares may begin to mirror the liquidity of the Fund’s underlying portfolio holdings, which can be significantly less liquid than Fund Shares. Trading in Fund Shares on the Exchange may be halted due to market conditions or for reasons that, in the view of the Exchange, make trading in Fund Shares inadvisable. In addition, trading in Fund Shares on the 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 the Exchange necessary to maintain the listing of the Fund will continue to be met or will remain unchanged.

SWAP AGREEMENTS RISK. The Fund may utilize swap agreements to derive its exposure Photonic and Optical Companies. Swap agreements may involve greater risks than direct investment in securities as they may be leveraged and are subject to credit risk, counterparty risk and valuation risk. A swap agreement could result in losses if the underlying reference or asset does not perform as anticipated. In addition, many swaps trade over-the-counter and may be considered illiquid. It may not be possible for the Fund to liquidate a swap position at an advantageous time or price, which may result in significant losses.

the value of investments. VIEs are not formally recognized under Chinese law and investors face uncertainty about future actions by the Chinese government that could significantly affect the operating company's financial performance and the enforceability of the contractual arrangements underlying the VIE structure. Prohibitions of these structures by the Chinese government, or the inability to enforce such contracts, from which the shell company derives its value, would likely cause the VIE-structured holding(s) to suffer significant losses, and in turn, adversely affect the Fund's returns and net asset value.

Performance

As of the date of this prospectus, the Fund has not yet commenced operations and therefore does not have a performance history. Once available, the Fund’s performance information will be accessible on the Fund’s website at https://www.roundhillinvestments.com/etf/lyte and will provide some indication of the risks of investing in the Fund.

Management

Investment Adviser: Roundhill Financial Inc. (“Roundhill” or the “Adviser”)

Investment Sub-Adviser: Exchange Traded Concepts, LLC (“ETC” or the “Sub-Adviser”)

Portfolio Managers: The individuals primarily responsible for the day-to-day management of the Fund are Timothy Maloney (Roundhill), William Hershey (Roundhill), David Mazza (Roundhill), Andrew Serowik (ETC), Todd Alberico (ETC), Gabriel Tan (ETC) and Brian Cooper (ETC). Each has served as a portfolio manager since its inception in [__].

Purchase and Sale of Fund Shares

The Fund will issue (or redeem) Fund Shares to certain institutional investors (typically market makers or other broker-dealers) only in large blocks of Fund Shares known as “Creation Units.” Creation Unit transactions are conducted in exchange for the deposit or delivery of a designated portfolio of in-kind securities and/or cash.

Individual Fund Shares may only be purchased and sold on the Exchange, other national securities exchanges, electronic crossing networks and other alternative trading systems through your broker-dealer at market prices. Because Fund Shares trade at market prices rather than at net asset value (“NAV”), Fund Shares may trade at a price greater than NAV (premium) or less than NAV (discount). When buying or selling Fund 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 Fund Shares (bid) and the lowest price a seller is willing to accept for Fund Shares (ask) (the “bid-ask spread”). Recent information regarding the Fund’s NAV, market price, premiums and discounts, and bid-ask spreads is available at https://www.roundhillinvestments.com/etf/lyte.

Tax Information

To the extent the Fund’s distributions are taxed, they are expected to be taxed as ordinary income, qualified dividend income and/or capital gains, unless you are investing through a tax-advantaged arrangement, such as a 401(k) plan or individual retirement account. Any withdrawals made from such

tax-advantaged arrangement may be taxable to you. Certain Fund distributions may exceed the Fund’s income and gains for the Fund’s taxable year. Distributions in excess of the Fund’s current and accumulated earnings and profits will be treated as a return of capital. A return of capital distribution generally will not be taxable but will reduce the shareholder’s cost basis and will result in a higher capital gain or lower capital loss when those Fund Shares on which the distribution was received are sold. Once a Fund shareholder’s cost basis is reduced to zero, further distributions will be treated as capital gain if the Fund shareholder holds Fund Shares as capital assets.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase Fund Shares through a broker-dealer or other financial intermediary (such as a bank), the Adviser, the Sub-Adviser, the Fund’s distributor, 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.

Additional Information About the Fund’s Principal Investment Strategies

Overview

The Fund is a series of Roundhill ETF Trust (the “Trust”) and is regulated as an “investment company” under the 1940 Act. The Fund is actively managed and does not seek to track the performance of an index. Each of the policies described herein, including the investment objective of the Fund, constitutes a non-fundamental policy that may be changed by the Board of Trustees of the Trust (the “Board”) without shareholder approval. Certain fundamental policies of the Fund are set forth in the Fund’s Statement of Additional Information (the “SAI”). There can be no assurance that the Fund’s objective will be achieved.

The Fund’s investments are subject to certain requirements imposed by law and regulation, as well as the Fund’s investment strategy. These requirements are generally applied at the time the Fund invests its assets. If, subsequent to an investment by the Fund, this requirement is no longer met, the Fund’s future investments will be made in a manner that will bring the Fund into compliance with this requirement.

Additional Information About the Fund’s Principal Investment Strategy

The Fund is an actively managed ETF that seeks to achieve its investment objective by investing in the equity securities of companies whose core technology involves generating, manipulating, detecting, or transmitting light for various technologies, such as AI data centers, defense, medical imaging, industrial manufacturing, and quantum computing (“Photonic and Optical Companies”). The Fund may also invest in securities offered in an initial public offering (“IPO”) or in companies that have recently completed an IPO.

The Fund’s adviser, Roundhill, identifies for potential investment Photonic and Optical Companies with at least 50% of their revenues attributable to the research, development, manufacturing, or sale of one or more of the following optical and/or photonic technologies:

• Optical transceivers and modules,

• Laser sources and photonic components,

• Silicon photonics (“SiPh”) integrated circuits,

• Optical interconnect systems,

• Photonic substrates and wafer materials,

• Photonic foundry and contract manufacturing services,

• Industrial and defense lasers,

• Precision photodetectors, sensors, and imaging systems,

• Fiber optic cable and connectivity infrastructure,

• Optical computing and photonic AI acceleration, and

• Related technologies in photonics and/or optics.

The Fund will seek to invest in those companies with a minimum market capitalization of $[__] and an average daily trading volume of at least $[__].The Fund may invest in U.S. and non-U.S. companies (including those operating in developed or emerging market countries) through investments in depositary receipts, ADRs or GDRs, including depositary receipts whose underlying securities are non-voting preferred securities. Such companies may be small-, mid- or large-capitalization issuers. The Fund rebalances its portfolio at least quarterly using the Adviser’s proprietary weighting methodology. The Fund does not actively trade securities between rebalances.

The Fund will concentrate (i.e., invest more than 25% of its total assets) its investments in the group of industries comprising the information technology sector.

The Fund is classified as “non-diversified” under the 1940 Act.

Non-Principal Strategies

Borrowing Money. The Fund may borrow money from a bank as permitted by the 1940 Act or the rules thereunder, or by the SEC or other regulatory agency with authority over the Fund. The 1940 Act presently allows a fund to borrow from any bank (including pledging, mortgaging or hypothecating assets) in an amount up to 33 1/3% of its total assets (not including temporary borrowings not in excess of 5% of its total assets).

Securities Lending. The Fund may lend its portfolio securities. A securities lending program allows the Fund to receive a portion of the income generated by lending its securities and investing the respective collateral. In connection with such loans, the Fund receives liquid collateral equal to at least 102% (105% for non-U.S. securities) of the value of the portfolio securities being lent. This collateral is marked to market on each trading day.

Additional Risks of Investing in the Fund

Risk is inherent in all investing. Investing in the Fund involves risk, including the risk that you may lose all or part of your investment. There can be no assurance that the Fund will meet its stated objective. Before you invest, you should consider the following supplemental disclosure pertaining to the Principal Risks set forth above as well as additional Non-Principal Risks set forth below in this prospectus.

Principal Risks

than preferred stocks and debt securities because common stockholders’ claims are subordinated to those of holders of preferred stocks and debt securities upon the bankruptcy of the issuer.

China Risk. The Fund my invest in instruments that provide exposure to Chinese companies, including through investments in China A-Shares, which would subject the Fund to risks specific to China. China may be subject to considerable degrees of economic, political and social instability. China is an emerging market and demonstrates significantly higher volatility from time to time in comparison to developed markets. Over the last few decades, the Chinese government has undertaken reform of economic and market practices and has expanded the sphere of private ownership of property in China. However, Chinese markets generally continue to experience inefficiency, volatility and pricing anomalies resulting from governmental influence, a lack of publicly available information and/or political and social instability.

Asset Class Risk. Securities and other assets in the Fund’s portfolio may underperform in comparison to the general financial markets, a particular financial market or other asset classes.

CONSUMER DISCRETIONARY SECTOR RISK. Consumer discretionary companies, such as retailers, media companies and consumer services companies, provide non-essential goods and services. These companies manufacture products and provide discretionary services directly to the consumer, and the success of these companies is tied closely to the performance of the overall domestic and international economy, interest rates, competition and consumer confidence. Success depends heavily on disposable household income and consumer spending. Changes in demographics and consumer tastes can also affect the demand for, and success of, consumer discretionary products in the marketplace.

the Fund’s business operations and/or potentially result in financial losses to the Fund and its shareholders. While the Fund has established business continuity plans and risk management systems seeking to address system breaches or failures, there are inherent limitations in such plans and systems. Furthermore, the Fund cannot control the cybersecurity plans and systems of the Fund’s other service providers, market makers, Authorized Participants or issuers of securities in which the Fund invests.

FORWARD CONTRACTS RISK. The Fund may utilize forward contracts to derive its exposure to Photonic and Optical Companies. A forward contract is an over-the-counter derivative transaction between two parties to buy or sell a specified amount of an underlying reference at a specified price (or rate) on a specified date in the future. Forward contracts are negotiated on an individual basis and are not standardized or traded on exchanges. The market for forward contracts is substantially unregulated and can experience lengthy periods of illiquidity, unusually high trading volume and other negative impacts, such as political intervention, which may result in volatility or disruptions in such markets. A relatively small price movement in a forward contract may result in substantial losses to the Fund, exceeding the amount of the margin paid.

Large Capitalization Companies Risk. Large capitalization companies may be less able than smaller capitalization companies to adapt to changing market conditions. Large capitalization companies may be more mature and subject to more limited growth potential compared with smaller capitalization companies. During different market cycles, the performance of large capitalization companies has trailed the overall performance of the broader securities markets.

more than if it invested in a larger number of issuers. The value of the Fund Shares may be more volatile than the values of shares of more diversified funds.

Structural ETF Risks. The Fund is an ETF. Accordingly, it is subject to certain risks associated with its unique structure.

or greater premiums or discounts to the Fund’s NAV. Furthermore, the Fund may not be able to execute cash transactions for creation and redemption purposes at the same price used to determine the Fund’s NAV. To the extent that the maximum additional charge for creation or redemption transactions is insufficient to cover the execution shortfall, the Fund’s performance could be negatively impacted.

Costs of Buying and Selling Fund Shares. Due to the costs of buying or selling Fund Shares, including brokerage commissions imposed by brokers and bid/ask spreads, frequent trading of Fund Shares may significantly reduce investment results and an investment in Fund Shares may not be advisable for investors who anticipate regularly making small investments.

discount to the net asset value, the shareholder may pay more for, or receive less than, the underlying value of the Fund Shares, respectively. This risk is heightened in times of market volatility or periods of steep market declines.

Variable Interest Risk. Exposure to VIEs may pose additional risks because the investment is made in reference to an intermediary shell company that has entered into service and other contracts with the underlying Chinese operating company to provide investors with exposure to the operating company, but does not represent equity ownership in the operating company. As a result, such investment may limit the rights of an investor with respect to the underlying Chinese operating company. VIEs allow foreign shareholders to exert a degree of control over, and obtain economic benefits arising from, the operating company without formal legal ownership. However, the contractual arrangements between the shell company and the operating company may not be as effective in providing operational control as direct equity ownership, and a foreign investor's rights may be limited by, for example, actions of the Chinese government which could determine that the underlying contractual arrangements on which control of the VIE is based are invalid. The contractual arrangement on which the VIE structure is based would likely be subject to Chinese law and jurisdiction, which could raise questions about how recourse is sought. Investments through VIEs may be affected by conflicts of interest and duties between the legal owners of the VIE and the stockholders of the listed holding company, which could adversely impact the value of investments. VIEs are not formally recognized under Chinese law and investors face uncertainty about future actions by the Chinese government that could significantly affect the operating company's financial performance and the enforceability of the contractual arrangements underlying the VIE structure. Prohibitions of these structures by the Chinese government, or the inability to enforce such contracts, from which the shell company derives its value, would likely cause the VIE-structured holding(s) to suffer significant losses, and in turn, adversely affect the Fund's returns and net asset value.

Non-Principal Risks

IPO RISK. The Fund may invest in securities offered in an IPO or in companies that have recently completed an IPO. The market value of IPO shares can have significant volatility due to factors such as the absence of a prior public market, unseasoned trading, a small number of shares available for trading and limited information about the issuer. The purchase of IPO shares may involve high transaction costs, and the Fund may lose money on an investment in such securities.

Regulated Investment Company Tax Risks. The Fund intends to qualify annually and to elect to be treated as a regulated investment company under the Internal Revenue Code of 1986, as amended (the “Code”). To qualify for the favorable U.S. federal income tax treatment generally accorded to regulated investment companies, the Fund must, among other things, (i) derive in each taxable year at least 90% of its gross income from dividends, interest, payments with respect to securities loans and gains from the sale or other disposition of stock, securities or foreign currencies or other income derived with respect to its business of investing in such stock, securities or currencies, or net income derived from interests in certain publicly traded partnerships; (ii) diversify its holdings so that, at the end of each quarter of the taxable year, (a) at least 50% of the market value of the Fund’s assets is represented by cash and cash items (including receivables), U.S. government securities, the securities of other regulated investment companies and other securities, with such other securities of any one issuer generally limited for the purposes of this calculation to an amount not greater than 5% of the value of the Fund’s total assets and not greater than 10% of the outstanding voting securities of such issuer, and (b) not more than 25% of the value of its total assets is invested in the securities (other than U.S. government securities or the securities of other regulated investment companies) of any one issuer, or two or more issuers which the Fund controls which are engaged in the same, similar or related trades or businesses, or the securities of one or more of certain publicly traded partnerships; and (iii) distribute at least 90% of its investment company taxable income (which includes, among other items, dividends, interest and net short-term capital gains in excess of net long-term capital losses) and at least 90% of its net tax-exempt interest income each taxable year. There are certain exceptions for failure to qualify if the failure is for reasonable cause or is de minimis, and certain corrective action is taken and certain tax payments are made by the Fund.

If the Fund were to fail to meet the qualifying income test or asset diversification test and fail to qualify as a RIC, it would be taxed in the same manner as an ordinary corporation, and distributions to its shareholders would not be deductible by the Fund in computing its taxable income, which would adversely affect the Fund’s performance.

Securities Lending Risk. There are certain risks associated with securities lending, including the risk that the borrower may fail to return the securities on a timely basis or even the loss of rights in the collateral deposited by the borrower, if the borrower should fail financially. The Fund could also lose money in the event of a decline in the value of collateral provided for loaned securities or a decline in the value of any investments made with cash collateral. As a result, the Fund may lose money.

Management of the Fund

The Fund is a series of Roundhill ETF Trust, an investment company registered under the 1940 Act. The Fund is treated as a separate fund with its own investment objectives and policies. The Trust is organized as a Delaware statutory trust. The Board is responsible for the overall management and

direction of the Trust. The Board elects the Trust’s officers and approves all significant agreements, including those with the Adviser, Sub-Adviser, distributor, custodian and fund administrative and accounting agent.

Investment Adviser. Roundhill Financial Inc., a Delaware corporation located at 154 West 14th Street, 2nd Floor, New York, New York 10011, serves as the investment adviser for the Fund. The Adviser is an SEC-registered investment adviser that has provided investment advisory services to pooled investment vehicles since 2019. The Adviser oversees the day-to-day operations of the Fund, subject to the general supervision and oversight of the Board. The Adviser also arranges for sub-advisory, transfer agency, custody, fund administration, distribution and all other services necessary for the Fund to operate. The Adviser continuously reviews, supervises, and administers the Fund’s investment program. In particular, the Adviser provides investment and operational oversight of the Sub-Adviser.

Investment Sub-Adviser. Exchange Traded Concepts, LLC, an Oklahoma limited liability company located at 10900 Hefner Pointe Drive, Suite 400, Oklahoma City, Oklahoma 73120, serves as the Fund’s investment sub-adviser. The Sub-Adviser is an SEC-registered investment adviser that has provided investment advisory or sub-advisory services to pooled investment vehicles since 2009, including to over 138 1940 Act-registered ETFs as of March 2026. ETC has responsibility for managing the Fund’s investment program in pursuit of its investment objective.

Portfolio Managers. William Hershey, CFA (Roundhill), Timothy Maloney, CFA (Roundhill), David Mazza (Roundhill), Andrew Serowik (ETC), Todd Alberico (ETC), Gabriel Tan (ETC) and Brian Cooper (ETC) serve as the Fund’s portfolio managers.

• Mr. Maloney co-founded Roundhill in late 2018. He began his career at Morgan Stanley as a Foreign-Exchange and Emerging Markets salesperson. He later joined Wells Capital, where he traded investment grade bonds for a $35 billion fixed-income portfolio. He graduated from Vanderbilt University with a degree in Economics and a Masters of Science in Finance (MSF). Mr. Maloney is a CFA Charterholder.

• Mr. Hershey co-founded Roundhill in late 2018. He began his career at Yorkville ETF Advisors, continuing with Yorkville Capital Management after the sale of Yorkville’s ETF business. During his career, he held various roles, including Head Trader for a Yorkville’s long/short energy hedge fund. He graduated from Vanderbilt University with a degree in Economics. Mr. Hershey is a CFA Charterholder.

• Mr. Mazza joined Roundhill in 2023. He began his career at State Street Global Advisors and had various research, portfolio management, and product development responsibilities including leading the strategy and research team for SPDR ETFs. He later worked in leadership roles at OppenheimerFunds and Rafferty Asset Management. He graduated from the Sawyer Business School at Suffolk University with his Masters of Business Administration (MBA) in Finance and Boston College with a degree in Political Science and Philosophy.

• Mr. Serowik joined ETC from Goldman Sachs. He began his career at Spear, Leeds & Kellogg, continuing with Goldman after its acquisition of SLK. During his career of more than 18 years at the combined companies, he held various roles, including managing the global Quant ETF Strats team and One Delta ETF Strats. He designed and developed systems for portfolio risk calculation,

algorithmic ETF trading, and execution monitoring, with experience across all asset classes. He graduated from the University of Michigan with a Bachelor of Business Administration degree in Finance.

• Mr. Alberico joined ETC in November 2020, having spent the past 14 years in ETF trading at Goldman Sachs, Cantor Fitzgerald, and, most recently, Virtu Financial. He spent most of that time focused on the Trading and Portfolio Risk Management of ETFs exposed to international and domestic equity. He has worked on several different strategies including lead market-making and electronic trading, to customer facing institutional business developing models for block trading as well as transitional trades. Mr. Alberico graduated from St. John’s University in New York with a Bachelor of Science degree in Finance.

• Mr. Tan joined ETC in May 2019 as an Associate Portfolio Manager and was promoted to Portfolio Manager in December 2020. He began his career at UBS and BBR Partners where he worked as a financial planning analyst and a portfolio strategist for over four years. During his time there, he developed comprehensive wealth management solutions focused on portfolio optimization, trust and estate planning, and tax planning. Mr. Tan graduated from the University of North Carolina at Chapel Hill with a Bachelor of Science in Business Administration with a concentration in Investments, a Bachelor of Arts in Economics, and a Minor in Chinese.

• Mr. Cooper joined ETC in November 2021 and currently serves as a Portfolio Manager. Previously, Mr. Cooper had roles in trade operations for Constellation Advisers from March 2017 until April 2018 and for QFR Capital Management from April 2018 until July 2020 and in the middle office derivatives group of Elliot Capital Management from September 2020 until November 2021. Prior to these roles, he spent 14 years working in various operational roles for Falcon Management Corporation, a global macro family office, gaining exposure to a variety of asset classes with a focus on operations, accounting, and technology. Mr. Cooper graduated from Pennsylvania State University with a Bachelor of Science in Finance and a minor in Business Law.

For additional information concerning Roundhill and ETC, including a description of the services provided to the Fund, please see the Fund’s SAI. Additional information regarding the portfolio managers’ compensation, other accounts managed by the portfolio managers and the portfolio managers’ ownership of Fund Shares may also be found in the SAI.

The Fund operates a multi-manager structure pursuant to an exemptive order issued by the SEC. The order permits Roundhill, subject to certain conditions, to enter into new or modified sub‑advisory agreements with existing or new sub‑advisers without the approval of Fund shareholders, but subject to approval by the Board. Roundhill has the ultimate responsibility for overseeing the Fund’s sub‑advisers and recommending their hiring, termination and replacement, subject to oversight by the Board. The order also grants Roundhill and the Fund relief with respect to the disclosure of the advisory fees paid to individual sub‑advisers in various documents filed with the SEC and provided to shareholders. Pursuant to this relief, the Fund may disclose the aggregate fees payable to Roundhill and wholly-owned sub‑advisers and the aggregate fees payable to unaffiliated sub‑advisers and sub‑advisers affiliated with Roundhill, other than wholly-owned sub‑advisers.

If the Fund relies on the order to hire a new sub‑adviser, the Fund will provide shareholders with certain information regarding the sub‑adviser within 90 days of hiring the new sub‑adviser, as required by the

order. In the future, Roundhill may propose the addition of one or more additional sub‑advisers, subject to approval by the Board and, if required by the 1940 Act, or any applicable exemptive relief, fund shareholders. The Prospectus will be supplemented if additional investment sub‑advisers are retained or the contract with any existing sub‑adviser is terminated.

Management Fee

Pursuant to an investment advisory agreement between Roundhill and the Trust, on behalf of the Fund (the “Investment Management Agreement”), the Fund has agreed to pay an annual unitary management fee to Roundhill in an amount equal to [__]% of its average daily net assets. This unitary management fee is designed to pay the Fund’s expenses and to compensate Roundhill for the services it provides to the Fund. Out of the unitary management fee, Roundhill pays substantially all expenses of the Fund, including sub-advisory fees, the cost of transfer agency, custody, fund administration, legal, audit and other service and license fees. However, Roundhill is not responsible for interest charges on any borrowings (including net interest expenses incurred in connection with an investment in reverse repurchase agreements or futures contracts), dividends and other expenses on securities sold short, taxes (of any kind or nature, including, but not limited to, income, excise, transfer and withholding taxes), brokerage commissions and other expenses incurred in placing orders for the purchase and sale of securities and other investment instruments (including any net account or similar fees charged by futures commission merchants) or in connection with creation and redemption transactions (including without limitation any fees, charges, taxes, levies or expenses related to the purchase or sale of an amount of any currency, or the patriation or repatriation of any security or other asset, related to the execution of portfolio transactions or any creation or redemption transactions), acquired fund fees and expenses, accrued deferred tax liability, fees and expenses payable related to the provision of securities lending services, legal fees or expenses in connection with any arbitration, litigation or pending or threatened arbitration or litigation, including any settlements in connection therewith, extraordinary expenses, and distribution fees and expenses paid by the Trust under any distribution plan adopted pursuant to Rule 12b-1 under the 1940 Act.

Pursuant to an investment sub-advisory agreement between Roundhill and ETC (the “Investment Sub-Advisory Agreement”), Roundhill has agreed to pay an annual sub‑advisory fee to ETC in an amount based on the Fund’s average daily net assets. Roundhill is responsible for paying the entirety of ETC’s sub-advisory fee. The Fund does not directly pay ETC.

A discussion regarding the basis for the Board’s approval of the Investment Management Agreement and the Investment Sub-Advisory Agreement on behalf of the Fund will be available in the Fund’s Form N-CSR.

How to Buy and Sell Shares

Fund Shares are listed for secondary trading on the Exchange and individual Fund Shares may only be purchased and sold in the secondary market through a broker-dealer. The Exchange and secondary markets are closed on weekends and also are generally closed on the following holidays: New Year’s Day, Dr. Martin Luther King, Jr. Day, Presidents’ Day, Good Friday, Memorial Day (observed), Juneteenth, Independence Day, Labor Day, Thanksgiving Day and Christmas Day. The Exchange may close early on the business day before certain holidays and on the day after Thanksgiving Day. Exchange holiday schedules are subject to change without notice. If you buy or sell Fund Shares in the secondary

market, you will pay the secondary market price for Fund Shares. In addition, you may incur customary brokerage commissions and charges and may pay some or all of the spread between the bid and the offered price in the secondary market on each leg of a round trip (purchase and sale) transaction.

The trading prices of Fund Shares will fluctuate continuously throughout trading hours based on market supply and demand rather than the Fund’s net asset value, which is calculated at the end of each business day. Fund Shares will trade on the Exchange at prices that may be above (i.e., at a premium) or below (i.e., at a discount), to varying degrees, the daily net asset value of Fund Shares. The trading prices of Fund Shares may deviate significantly from the Fund’s net asset value during periods of market volatility. Given, however, that Fund Shares can be issued and redeemed daily in Creation Units, the Adviser believes that large discounts and premiums to net asset value should not be sustained over long periods.

Book Entry

Fund Shares are held in book-entry form, which means that no stock certificates are issued. The Depository Trust Company (“DTC”) or its nominee is the record owner of, and holds legal title to, all outstanding Fund Shares. Investors owning Fund Shares are beneficial owners as shown on the records of DTC or its participants. DTC serves as the securities depository for Fund Shares.

DTC participants include securities brokers and dealers, banks, trust companies, clearing corporations and other institutions that directly or indirectly maintain a custodial relationship with DTC. As a beneficial owner of Fund Shares, you are not entitled to receive physical delivery of stock certificates or to have Fund Shares registered in your name, and you are not considered a registered owner of Fund Shares. Therefore, to exercise any right as an owner of Fund Shares, you must rely upon the procedures of DTC and its participants. These procedures are the same as those that apply to any other securities that you hold in book-entry or “street name” form.

Dividends, Distributions and Taxes

Ordinarily, dividends from net investment income, if any, are declared and paid at least annually by the Fund. The Fund distributes its net realized capital gains, if any, to shareholders annually.

Distributions in cash may be reinvested automatically in additional whole Fund Shares only if the broker through whom you purchased Fund Shares makes such option available.

Taxes

This section summarizes some of the main U.S. federal income tax consequences of owning shares of the Fund. This section is current as of the date of this prospectus. Tax laws and interpretations change frequently, and these summaries do not describe all of the tax consequences to all taxpayers. For example, these summaries generally do not describe your situation if you are a corporation, a non‑U.S. person, a broker‑dealer, or other investor with special circumstances. In addition, this section does not describe your state, local or non‑U.S. tax consequences.

This federal income tax summary is based in part on the advice of counsel to the Fund. The Internal Revenue Service could disagree with any conclusions set forth in this section. In addition, counsel to the Fund may not have been asked to review, and may not have reached a conclusion with respect to, the

federal income tax treatment of the assets to be included in the Fund. The following disclosure may not be sufficient for you to use for the purpose of avoiding penalties under federal tax law.

As with any investment, you should seek advice based on your individual circumstances from your own tax advisor.

Fund Status. The Fund intends to qualify as a “regulated investment company” under the federal tax laws. If the Fund qualifies as a regulated investment company and distributes its income as required by the tax law, the Fund generally will not pay federal income taxes.

Distributions. The Fund’s distributions are generally taxable. After the end of each year, you will receive a tax statement that separates the distributions of the Fund into three categories: ordinary income distributions, capital gain dividends and returns of capital. Ordinary income distributions are generally taxed at your ordinary tax rate, however, as further discussed below certain ordinary income distributions received from the Fund may be taxed at the capital gains tax rates. Generally, you will treat all capital gain dividends as long-term capital gains regardless of how long you have owned your Fund Shares.

To determine your actual tax liability for your capital gain dividends, you must calculate your total net capital gain or loss for the tax year after considering all of your other taxable transactions, as described below. In addition, the Fund may make distributions that represent a return of capital for tax purposes and thus will generally not be taxable to you unless the distribution exceeds a shareholder’s basis in the Fund Shares; however, such distributions may reduce your tax basis in your Fund Shares, which could result in you having to pay higher taxes in the future when Fund Shares are sold, even if you sell the Fund Shares at a loss from your original investment. A “return of capital” is a return, in whole or in part, of the funds that you previously invested in the Fund. A return of capital distribution should not be considered part of the Fund’s dividend yield or total return of an investment in Fund Shares. The tax status of your distributions from the Fund is not affected by whether you reinvest your distributions in additional Fund Shares or receive them in cash. The income from the Fund that you must take into account for federal income tax purposes is not reduced by amounts used to pay a deferred sales fee, if any. The tax laws may require you to treat distributions made to you in January as if you had received them on December 31 of the previous year.

Income from the Fund may also be subject to a 3.8% “Medicare tax.” This tax generally applies to your net investment income if your adjusted gross income exceeds certain threshold amounts, which are $250,000 in the case of married couples filing joint returns and $200,000 in the case of single individuals.

Dividends Received Deduction. A corporation that owns Fund Shares generally may not be entitled to the dividends received deduction with respect to many dividends received from the Fund because the dividends received deduction is generally not available for distributions from RICs. However, certain ordinary income dividends on Fund Shares that are attributable to qualifying dividends received by the Fund from certain corporations may be reported by the Fund as being eligible for the dividends received deduction.

Capital Gains and Losses and Certain Ordinary Income Dividends. If you are an individual, the maximum marginal stated federal tax rate for net capital gains is generally 20% (15% or 0% for taxpayers with taxable incomes below certain thresholds). Some capital gains, including some portion of your

capital gain dividends may be taxed at a higher maximum stated tax rate. Capital gains may also be subject to the Medicare tax described above.

Net capital gain equals net long-term capital gain minus net short-term capital loss for the taxable year. Capital gain or loss is long-term if the holding period for the asset is more than one year and is short-term if the holding period for the asset is one year or less. You must exclude the date you purchase your Fund Shares to determine your holding period. However, if you receive a capital gain dividend from the Fund and sell your Fund Shares at a loss after holding them for six months or less, the loss will be recharacterized as long-term capital loss to the extent of the capital gain dividend received. The tax rates for capital gains realized from assets held for one year or less are generally the same as for ordinary income. The Internal Revenue Code of 1986, as amended, treats certain capital gains as ordinary income in special situations.

In general, ordinary income dividends are taxed at ordinary income rates. Ordinary income dividends received by an individual shareholder from a RIC such as the Fund are generally taxed at the same rates that apply to net capital gain (as discussed above), provided certain holding period requirements are satisfied and provided the dividends are attributable to qualifying dividends received by the Fund itself. The Fund will provide notice to its shareholders of the amount of any distribution which may be taken into account as a dividend which is eligible for the capital gains tax rates.

Sale of Fund Shares. If you sell or redeem your Fund Shares, you will generally recognize a taxable gain or loss. To determine the amount of this gain or loss, you must subtract your tax basis in your Fund Shares from the amount you receive in the transaction. Your tax basis in your Fund Shares is generally equal to the cost of your Fund Shares, generally including brokerage fees, if any. In some cases, however, you may have to adjust your tax basis after you purchase your Fund Shares. An election may be available to you to defer recognition of capital gain if you make certain qualifying investments within a limited time. You should talk to your tax advisor about the availability of this deferral election and its requirements.

Taxes on Purchase and Redemption of Creation Units. If you exchange securities for Creation Units, you will generally recognize a gain or a loss. The gain or loss will be equal to the difference between the market value of the Creation Units at the time and your aggregate basis in the securities surrendered and the cash component paid. If you exchange Creation Units for securities, you will generally recognize a gain or loss equal to the difference between your basis in the Creation Units and the aggregate market value of the securities received and the cash redemption amount. The IRS, however, may assert that a loss realized upon an exchange of securities for Creation Units or Creation Units for securities cannot be deducted currently under the rules governing “wash sales,” or on the basis that there has been no significant change in economic position.

Treatment of Expenses. Expenses incurred and deducted by the Fund will generally not be treated as income taxable to you.

Non-U.S. Tax Credit. Because the Fund may invest in non-U.S. securities, the tax statement that you receive may include an item showing non-U.S. taxes the Fund paid to other countries. In this case, dividends taxed to you will include your share of the taxes the Fund paid to other countries. You may be able to deduct or receive a tax credit for your share of these taxes.

Non-U.S. Investors. If you are a non-U.S. investor (i.e., an investor other than a U.S. citizen or resident or a U.S. corporation, partnership, estate or trust), you should be aware that, generally, subject to applicable tax treaties, distributions from the Fund are characterized as dividends for federal income tax purposes (other than dividends which the Fund properly reports as capital gain dividends) are subject to U.S. federal income taxes, including withholding taxes, subject to certain exceptions described below. However, distributions received by a non-U.S. investor from the Fund that are properly reported by the Fund as capital gain dividends may not be subject to U.S. federal income taxes, including withholding taxes, provided that the Fund makes certain elections and certain other conditions are met. Distributions from the Fund that are properly reported by the Fund as an interest-related dividend attributable to certain interest income received by the Fund or as short-term capital gain income dividend attributable to certain net short term capital gain received by the Fund may not be subject to U.S. federal income taxes, including withholding taxes when received by certain non-U.S. investors, provided that the Fund makes certain elections and certain other conditions are met. For tax years after December 31, 2022, amounts paid to or recognized by a non-U.S. affiliate that are excluded from tax under the portfolio interest, capital gain dividends, short-term capital gains or tax-exempt interest dividend exceptions or applicable treaties, may be taken into consideration in determining whether a corporation is an “applicable corporation” subject to a 15% minimum tax on adjusted financial statement income.

Distributions may be subject to a U.S. withholding tax of 30% in the case of distributions to (i) certain non-U.S. financial institutions that have not entered into an agreement with the U.S. Treasury to collect and disclose certain information and are not resident in a jurisdiction that has entered into such an agreement with the U.S. Treasury and (ii) certain other non-U.S. entities that do not provide certain certifications and information about the entity’s U.S. owners. This withholding tax is also currently scheduled to apply to the gross proceeds from the disposition of securities that produce U.S. source interest or dividends. However, proposed regulations may eliminate the requirement to withhold on payments of gross proceeds from dispositions.

It is the responsibility of the entity through which you hold your Fund Shares to determine the applicable withholding.

Investments in Certain Non-U.S. Corporations. If the Fund holds an equity interest in any “passive foreign investment companies” (“PFICs”), which are generally certain non-U.S. corporations that receive at least 75% of their annual gross income from passive sources (such as interest, dividends, certain rents and royalties or capital gains) or that hold at least 50% of their assets in investments producing such passive income, the Fund could be subject to U.S. federal income tax and additional interest charges on gains and certain distributions with respect to those equity interests, even if all the income or gain is timely distributed to its shareholders. The Fund will not be able to pass through to its shareholders any credit or deduction for such taxes. The Fund may be able to make an election that could ameliorate these adverse tax consequences. In this case, the Fund would recognize as ordinary income any increase in the value of such PFIC shares, and as ordinary loss any decrease in such value to the extent it did not exceed prior increases included in income. Under this election, the Fund might be required to recognize in a year income in excess of its distributions from PFICs and its proceeds from dispositions of PFIC stock during that year, and such income would nevertheless be subject to the distribution requirement and would be taken into account for purposes of the 4% excise tax. Dividends paid by PFICs are not treated as qualified dividend income.

The foregoing discussion summarizes some of the possible consequences under current federal tax law of an investment in the Fund. It is not a substitute for personal tax advice. You also may be subject to state and local taxes on Fund distributions and sales of Fund Shares.

Distributor

Foreside Fund Services, LLC serves as the distributor of Creation Units for the Fund on an agency basis. The distributor does not maintain a secondary market in Fund Shares.

Net Asset Value

The NAV of the Fund normally is determined once daily Monday through Friday, generally as of the close of regular trading hours of the New York Stock Exchange (“NYSE”) (normally 4:00 p.m., Eastern time) on each day that the NYSE is open for trading, based on prices at the time of closing, provided that any Fund assets or liabilities denominated in currencies other than the U.S. dollar are translated into U.S. dollars at the prevailing market rates on the date of valuation as quoted by one or more data service providers. The NAV of the Fund is calculated by dividing the value of the net assets of the Fund (i.e., the value of its total assets less total liabilities) by the total number of outstanding Fund Shares, generally rounded to the nearest cent.

The Board has adopted valuation policies and procedures pursuant to which it has designated the Adviser to determine the fair value of the Fund’s investments, subject to the Board’s oversight, when market prices for those investments are not “readily available,” including when they are determined by the Adviser to be unreliable. Such circumstances may arise when: (i) a security has been de-listed or its trading halted or suspended; (ii) a security’s primary pricing source is unable or unwilling to provide a price; (iii) a security’s primary trading market is closed during regular market hours; or (iv) a security’s value has been materially affected by events occurring after the close of the security’s primary trading market and before a Fund calculates its NAV. Generally, when determining the fair value of a Fund investment, the Adviser will take into account all reasonably available information that may be relevant to a particular valuation including, but not limited to, fundamental analytical data regarding the issuer, information relating to the issuer’s business, recent trades or offers of the security, general and/or specific market conditions and the specific facts giving rise to the need to fair value the security. Fair value determinations are made in good faith and in accordance with the fair value methodologies established by the Adviser. Due to the subjective and variable nature of determining the fair value of a security or other investment, there can be no assurance that the Adviser’s determined fair value will match or closely correlate to any market quotation that subsequently becomes available or the price quoted or published by other sources. In addition, the Fund may not be able to obtain the fair value assigned to an investment if the Fund were to sell such investment at or near the time its fair value is determined.

Fund Service Providers

U.S. Bancorp Fund Services, LLC is the administrator and transfer agent for the Trust. U.S. Bank National Association serves as the custodian for the Trust.

Chapman and Cutler LLP, 320 South Canal Street, Chicago, Illinois 60606, serves as legal counsel to the Trust.

Cohen & Company, Ltd., 1835 Market Street, Suite 310, Philadelphia, Pennsylvania 19103, serves as the Fund’s independent registered public accounting firm and is responsible for auditing the annual financial statements of the Fund.

Premium/Discount Information

Information showing the number of days the market price of the Fund Shares was greater (at a premium) and less (at a discount) than the Fund’s NAV for the most recently completed calendar year, and the most recently completed calendar quarters since that year (or the life of the Fund, if shorter), is available at https://www.roundhillinvestments.com/etf/lyte.

Investments by Other Investment Companies

Section 12(d)(1) of the 1940 Act restricts investments by investment companies in the securities of other investment companies, including Fund Shares. The SEC has adopted Rule 12d1-4 under the 1940 Act. The Fund is required to comply with the conditions of Rule 12d1-4, which allows, subject to certain conditions, the Fund to invest in other registered investment companies and other registered investment companies to invest in the Fund beyond the limits contained in Section 12(d)(1) of the 1940 Act.

Financial Highlights

The Fund is new and has no performance history as of the date of this prospectus. Financial information is therefore not available.

Roundhill Photonics & Optics ETF

For more detailed information on the Fund, several additional sources of information are available to you. The Fund’s SAI, incorporated by reference into this prospectus, contains detailed information on the Fund’s policies and operation. Additional information about the Fund’s investments is available in the annual and semi‑annual reports to shareholders. In the Fund’s annual reports, you will find a discussion of the market conditions and investment strategies that significantly impacted the Fund’s performance during the last fiscal year. The Fund’s most recent SAI, annual or semi‑annual reports and certain other information are available free of charge by calling the Fund at (855) 561-5728, on the Fund’s website at www.roundhillinvestments.com/etf/lyte or through your financial advisor. Shareholders may call the toll‑free number above with any inquiries.

You may obtain this and other information regarding the Fund, including the SAI and Codes of Ethics adopted by the Adviser, Sub-Adviser and the Trust, directly from the SEC. Information on the SEC’s website is free of charge. Visit the SEC’s on‑line EDGAR database at http://www.sec.gov. You may also request information regarding the Fund by sending a request (along with a duplication fee) to the SEC by sending an electronic request to [email protected].

Roundhill Investments

154 West 14^th Street, 2^nd Floor

New York, New York 10011

(646) 661-5441

www.roundhillinvestments.com

SEC File #333-273052

811-23887