Prospectus by Investment Company (Form 497)

Rule 497(e)

Registration Nos. 333-273052 and 811-23887

Roundhill ETF Trust

(the "Trust")

Roundhill Robotaxi, Autonomous Vehicles & Technology ETF

Roundhill Space & Technology ETF

(the "Funds")

Supplement to the Funds' Statement of Additional Information

Dated April 22, 2026

Notwithstanding anything to the contrary in the Funds' statement of additional information, the section entitled "Creation and Redemption of Creation Units" is hereby deleted in its entirety and replaced with the following:

"Creation and Redemption of Creation Units"

General. ETFs, such as the Funds, generally issue and redeem their shares in primary market transactions through a creation and redemption mechanism and do not sell or redeem individual shares. Instead, financial entities, known as "Authorized Participants," have contractual arrangements with an ETF or one of the ETF's service providers to purchase and redeem ETF shares directly with the ETF in large blocks of shares known as "Creation Units." Prior to start of trading on each business day, an ETF publishes through the NSCC the "basket" of securities, cash or other assets that it will accept in exchange for a Creation Unit of the ETF's shares. An Authorized Participant that wishes to effectuate a creation of an ETF's shares deposits with the ETF the "basket" of securities, cash or other assets identified by the ETF that day, and then receives the Creation Unit of the ETF's shares in return for those assets. After purchasing a Creation Unit, the Authorized Participant may continue to hold the ETF's shares or sell them in the secondary market. The redemption process is the reverse of the purchase process: the authorized participant redeems a Creation Unit of ETF shares for a basket of securities, cash or other assets. The combination of the creation and redemption process with secondary market trading in ETF shares and underlying securities provides arbitrage opportunities that are designed to help keep the market price of ETF shares at or close to the NAV per share of the ETF.

Each Authorized Participant is a member or participant of a clearing agency registered with the SEC that has a written agreement with a Fund or one of its service providers that allows the Authorized Participant to place orders for the purchase or redemption of Creation Units (a "Participant Agreement"). Orders to purchase Creation Units must be delivered through an Authorized Participant that has executed a Participant Agreement and must comply with the applicable provisions of such Participant Agreement. Investors wishing to purchase or sell Fund Shares generally do so on an exchange. Institutional investors other than Authorized Participants are responsible for making arrangements for a redemption request to be made through an Authorized Participant.

A "Business Day" is generally any day on which the NYSE, the Exchange and the Trust are open for business. As of the date of this SAI, the NYSE observes the following holidays: New Year's Day, Martin Luther King, Jr. Day, Presidents' Day, Good Friday, Memorial Day, Juneteenth, Independence Day, Labor Day, Thanksgiving Day and Christmas Day. The Business Day on which an order to purchase or redeem Creation Units is received in proper form is referred to as the "Transmittal Date."

Basket Composition and Custom Baskets. Rule 6c-11(c)(3) under of the 1940 Act requires an ETF relying on the exemptions offered by Rule 6c-11 to adopt and implement written policies and procedures governing the construction of baskets and the process that the ETF will use for the acceptance of baskets. In general, in connection with the construction and acceptance of baskets, the Adviser may consider various factors, including, but not limited to: (1) whether the securities, assets and other positions comprising a basket are consistent with the ETF's investment objective(s), policies and disclosure; (2) whether the securities, assets and other positions can legally and readily be acquired, transferred and held by the ETF and/or Authorized Participant(s), as applicable; (3) whether to utilize cash, either in lieu of securities or other instruments or as a cash balancing amount; and (4) in the case of an ETF that tracks an index, whether the securities, assets and other positions aid index tracking.

Each Fund may utilize a pro-rata basket or a custom basket in reliance on Rule 6c-11. A "pro-rata basket" is a basket that is a pro rata representation of the ETF's portfolio holdings, except for minor deviations when it is not operationally feasible to include a particular instrument within the basket, except to the extent that the Fund utilized different baskets in transactions on the same Business Day.

Rule 6c-11 defines "custom baskets" to include two categories of baskets. First, a basket containing a non-representative selection of the ETF's portfolio holdings would constitute a custom basket. These types of custom baskets include, but are not limited to, baskets that do not reflect: (i) a pro rata representation of a Fund's portfolio holdings; (ii) a representative sampling of an ETF's portfolio holdings; or (iii) changes due to a rebalancing or reconstitution of an ETF's securities market index, if applicable. Second, if different baskets are used in transactions on the same Business Day, each basket after the initial basket would constitute a custom basket. For example, if an ETF exchanges a basket with either the same or another Authorized Participant that reflects a representative sampling that differs from the initial basket, that basket (and any such subsequent baskets) would be a custom basket. Similarly, if an ETF substitutes cash in lieu of a portion of basket assets for a single Authorized Participant, that basket would be a custom basket.

Under a variety of circumstances, an ETF and its shareholders may benefit from the flexibility afforded by custom baskets. In general terms, the use of custom baskets may reduce costs, increase efficiency and improve trading. Because utilizing custom baskets provides a way for an ETF to add, remove and re-weight portfolio securities without transacting in the market, it may help the ETF to avoid transaction costs and adverse tax consequences. Rule 6c-11 provides an ETF with flexibility to use "custom baskets" if the ETF has adopted written policies and procedures that: (1) set forth detailed parameters for the construction and acceptance of custom baskets that are in the best interests of the ETF and its shareholders, including the process for any revisions to, or deviations from, those parameters; and (2) specify the titles or roles of employees of the ETF's investment adviser who are required to review each custom basket for compliance with those parameters.

The use of baskets that do not correspond to pro rata to an ETF's portfolio holdings has historically created concern that an Authorized Participant could take advantage of its relationship with an ETF and pressure the ETF to construct a basket that favors an Authorized Participant to the detriment of the ETF's shareholders. For example, because ETFs rely on Authorized Participants to maintain the secondary market by promoting an effective arbitrage mechanism, an Authorized Participant holding less liquid or less desirable securities potentially could pressure an ETF into accepting those securities in its basket in exchange for liquid ETF shares (i.e., dumping). An Authorized Participant also could pressure the ETF into including in its basket certain desirable securities in exchange for ETF shares tendered for redemption (i.e., cherry-picking). In either case, the ETF's other investors would be disadvantaged and would be left holding shares of an ETF with a less liquid or less desirable portfolio of securities. The Adviser has adopted policies and procedures designed to mitigate these concerns but there is ultimately no guarantee that such policies and procedures will be effective.

Basket Dissemination.  Basket files are published for consumption through the NSCC, a subsidiary of Depository Trust & Clearing Corporation, and can be utilized for pricing, creations, redemptions, rebalancing and custom scenarios. In most instances, pro rata baskets are calculated and supplied by the ETF's custodial bank based on ETF holdings, whereas non-pro-rata, custom and forward-looking pro rata baskets are calculated by the Adviser and disseminated by the ETF's custodial bank through the NSCC process.

Placement of Creation or Redemption Orders. All orders to purchase or redeem Creation Units are to be governed according to the applicable Participant Agreement that each Authorized Participant has executed. In general, all orders to purchase or redeem Creation Units must be received by the transfer agent in the proper form required by the Participant Agreement no later than the closing time of the regular trading session of the NYSE (ordinarily 4:00 p.m. Eastern Standard Time) on each day the NYSE is open for business (the "Closing Time") in order for the purchase or redemption of Creation Units to be effected based on the NAV of Fund shares as next determined on such date after receipt of the order in proper form. However, at its discretion, a Fund may require an Authorized Participant to submit orders to purchase or redeem Creation Units be placed earlier in the day (such as instances where an applicable market for a security comprising a creation or redemption basket closes earlier than usual).

Delivery of Redemption Proceeds.  Deliveries of securities to Authorized Participants in connection with redemption orders are generally expected to be made within one Business Day. Due to the schedule of holidays in certain countries, however, the delivery of in-kind redemption proceeds for a Fund may take longer than one Business Day after the day on which the redemption request is received in proper form. Section 22(e) of the 1940 Act generally prohibits a registered open-end management investment company from postponing the date of satisfaction of redemption requests for more than seven days after the tender of a security for redemption. This prohibition can cause operational difficulties for ETFs that hold foreign investments and exchange in-kind baskets for Creation Units. For example, local market delivery cycles for transferring foreign investments to redeeming investors, together with local market holiday schedules, can sometimes require a delivery process in excess of seven days. However, Rule 6c-11 grants relief from Section 22(e) to permit an ETF to delay satisfaction of a redemption request for more than seven days if a local market holiday, or series of consecutive holidays, or the extended delivery cycles for transferring foreign investments to redeeming Authorized Participants, or the combination thereof prevents timely delivery of the foreign investment included in the ETF's basket. Under this exemption, an ETF must deliver foreign investments as soon as practicable, but in no event later than 15 days after the tender to the ETF. The exemption therefore will permit a delay only to the extent that additional time for settlement is actually required, when a local market holiday, or series of consecutive holidays, or the extended delivery cycles for transferring foreign investments to redeeming authorized participants prevents timely delivery of the foreign investment included in the ETF's basket. If a foreign investment settles in less than 15 days, Rule 6c-11 requires an ETF to deliver it pursuant to the standard settlement time of the local market where the investment trades. Rule 6c-11 defines "foreign investment" as any security, asset or other position of the ETF issued by a foreign issuer (as defined by Rule 3b-4 under the 1934 Act), and that is traded on a trading market outside of the United States. This definition is not limited to "foreign securities," but also includes other investments that may not be considered securities. Although these other investments may not be securities, they may present the same challenges for timely settlement as foreign securities if they are transferred in kind.

Creation Transaction Fees.  Each Fund imposes fees in connection with the purchase of Creation Units. These fees may vary based upon various facts-based circumstances, including, but not limited to, the composition of the securities included in the Creation Unit or the countries in which the transactions are settled. The price for each Creation Unit will equal the daily NAV per Fund Share times the number of Fund Shares in a Creation Unit, plus the fees described above and, if applicable, any operational processing and brokerage costs, transfer fees, stamp taxes and part or all of the spread between the expected bid and offer side of the market related to the securities comprising the creation basket. Payment of fees and expenses payable upon transfer of beneficial ownership of the deposit securities will be the sole responsibility of the Authorized Participant that purchased the Creation Unit, and the Authorized Participant will be required to ensure that any deposit securities properly denote change in beneficial ownership. If the NAV of the Fund per Creation Unit is less than the value of the deposit made by the Authorized Participant, the Fund may determine it is appropriate to return all or a portion of this excess amount to the Authorized Participant.

Redemption Transaction Fees.  Each Fund also imposes fees in connection with the redemption of Creation Units. These fees may vary based upon various facts-based circumstances, including, but not limited to, the composition of the securities included in the Creation Unit or the countries in which the transactions are settled. The price received for each Creation Unit will equal the daily NAV per Fund Share times the number of shares in a Creation Unit, minus the fees described above and, if applicable, any operational processing and brokerage costs, transfer fees, stamp taxes and part or all of the spread between the expected bid and offer side of the market related to the securities comprising the redemption basket. Investors who use the services of a broker or other such intermediary in addition to an Authorized Participant to effect a redemption of a Creation Unit may also be assessed an amount to cover the cost of such services. The redemption fee charged by the Fund will comply with Rule 22c-2 of the 1940 Act which limits redemption fees to no more than 2% of the value of the Fund Shares redeemed.

Suspension of Creations.  The SEC has stated its position that an ETF generally may suspend the issuance of Creation Units only for a limited time and only due to extraordinary circumstances, such as when the markets on which the ETF's portfolio holdings are traded are closed for a limited period of time. The SEC has also stated that an ETF could not set transaction fees so high as to effectively suspend the issuance of Creation Units. Circumstances in which a Fund may suspend creations include, but are not limited to: (i) the order is not in proper form; (ii) the purchaser or group of related purchasers, upon obtaining the Creation Units of Fund Shares ordered, would own 80% or more of the currently outstanding Fund Shares; (iii) the required consideration is not delivered; (iv) the acceptance of the basket would, in the opinion of the Fund, be unlawful; or (v) there exist circumstances outside the control of the Fund that make it impossible to process purchases of Creation Units for all practical purposes. Examples of such circumstances include: acts of God or public service or utility problems such as fires, floods, extreme weather conditions and power outages resulting in telephone, telecopy and computer failures; market conditions or activities causing trading halts; systems failures involving computer or other information systems affecting the Fund, the Adviser, the Distributor, DTC, NSCC, the transfer agent, the custodian, any sub-custodian or any other participant in the purchase process; and similar extraordinary events. A Fund reserves the right to reject a creation order transmitted to it provided that such action does not result in a suspension of sales of creation units in contravention of 6c-11 and the SEC's positions thereunder. The Transfer Agent shall notify a prospective creator of a Creation Unit and/or the Authorized Participant acting on behalf of such prospective creator of the rejection of the order of such person. The Trust, the Funds, the transfer agent, the custodian, any sub-custodian and the Distributor are under no duty, however, to give notification of any defects or irregularities in the delivery of baskets, nor shall any of them incur any liability for the failure to give any such notification.

Suspension of Redemptions.  An ETF may suspend the redemption of Creation Units only in accordance with Section 22(e) of the 1940 Act. Section 22(e) stipulates that no registered investment company shall suspend the right of redemption, or postpone the date of payment or satisfaction upon redemption of any redeemable security in accordance with its terms for more than seven days after the tender of such security to the company or its agent designated for that purpose for redemption, except (1) for any period (A) during which the NYSE is closed other than customary week-end and holiday closings or (B) during which trading on the NYSE is restricted; (2) for any period during which an emergency exists as a result of which (A) disposal by the investment company of securities owned by it is not reasonably practicable or (B) it is not reasonably practicable for such company fairly to determine the value of its net assets; or (3) for such other periods as the SEC may by order permit for the protection of security holders of the investment company.

Exceptions to Use of Creation Units.  Under Rule 6c-11 of the 1940 Act, ETFs are permitted to sell or redeem individual shares on the day of consummation of a reorganization, merger, conversion, or liquidation. In these limited circumstances, an ETF may need to issue or redeem individual shares and may need to transact without utilizing Authorized Participants."

Please Keep this Supplement for Future Reference