0001618627 2026-09-01 2026-09-01 0001618627 rbbtos:S000098129Member 2026-09-01 2026-09-01 0001618627 rbbtos:S000098129Member rbbtos:EmergingMarketsRiskMember 2026-09-01 2026-09-01 0001618627 rbbtos:S000098129Member rbbtos:ForeignSecuritiesRiskMember 2026-09-01 2026-09-01 false 497 N-1A 0001618627 <p id="xdx_A81_eoef--SupplementToProspectusTextBlock_zQoE8nORKUBc" style="font: 11pt Times New Roman, Times, Serif; margin: 0; text-align: center"><b>THE <span id="xdx_905_edei--EntityRegistrantName_c20260901__20260901_zY3ka4vndKS">RBB FUND TRUST</span></b></p> <p style="font: 11pt Times New Roman, Times, Serif; margin: 0"> </p> <p style="font: 11pt Times New Roman, Times, Serif; margin: 0; text-align: center"><b>Twin Oak Strategic Solutions ETF (the “Fund”)</b></p> <p style="font: 11pt Times New Roman, Times, Serif; margin: 0; text-align: center"> (CBOE BZX: TOS)</p> <p style="font: 11pt Times New Roman, Times, Serif; margin: 0"> </p> <p style="font: 11pt Times New Roman, Times, Serif; margin: 0; text-align: center">Supplement dated <span id="xdx_902_edei--DocumentPeriodEndDate_c20260901__20260901_zGNVgefz05lh">September 1, 2026</span></p> <p style="font: 11pt Times New Roman, Times, Serif; margin: 0; text-align: center"> </p> <p style="font: 11pt Times New Roman, Times, Serif; margin: 0; text-align: center">to the Summary Prospectus, Statutory Prospectus and Statement of Additional <br/> Information (“SAI”) dated <span id="xdx_902_eoef--ProspectusDate_c20260901__20260901_zKudtErySxl9">December 15, 2025</span>, as supplemented on January 22, 2026</p> <p style="font: 11pt Times New Roman, Times, Serif; margin: 0; text-align: center"> </p> <div style="margin-top: 1pt; margin-bottom: 1pt; width: 100%"><div style="border-top: Black 1.5pt solid; font-size: 1pt"> </div></div> <p style="font: 11pt Times New Roman, Times, Serif; margin: 0; text-align: center"> </p> <p style="font: 11pt Times New Roman, Times, Serif; margin: 0; text-align: justify"><i>This supplement serves as notification of the following changes effective as of September 1, 2026:</i></p> <p style="font: 11pt Times New Roman, Times, Serif; margin: 0"> </p> <table cellpadding="0" cellspacing="0" style="font: 11pt Times New Roman, Times, Serif; width: 100%; margin-top: 0; margin-bottom: 0"><tr style="vertical-align: top"> <td style="width: 0"></td><td style="width: 0.25in">1.</td><td style="text-align: justify">The Fund may now invest in international securities as part of its principal investment strategies.</td></tr></table> <p style="font: 11pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p> <table cellpadding="0" cellspacing="0" style="font: 11pt Times New Roman, Times, Serif; width: 100%; margin-top: 0; margin-bottom: 0"><tr style="vertical-align: top"> <td style="width: 0.5in"></td><td style="width: 0.25in">a.</td><td style="text-align: justify">The second sentence of the Principal Investment Strategies section in the Summary Section of the Fund’s Prospectus and the Summary Prospectus is replaced with the following:</td></tr></table> <p style="font: 11pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p> <p style="font: 11pt Times New Roman, Times, Serif; margin: 0 0 0 1in; text-align: justify">The Fund seeks to achieve its investment objective by investing in domestic and international equity securities (e.g. common and preferred stock) of all market capitalizations.</p> <p style="font: 11pt Times New Roman, Times, Serif; margin: 0 0 0 0.5in; text-align: justify"> </p> <table cellpadding="0" cellspacing="0" style="font: 11pt Times New Roman, Times, Serif; width: 100%; margin-top: 0; margin-bottom: 0"><tr style="vertical-align: top"> <td style="width: 0.5in"></td><td style="width: 0.25in">b.</td><td style="text-align: justify">The following are added to the Principal Investment Risks in the Summary Section of the Fund’s Prospectus and the Summary Prospectus.</td></tr></table> RBB FUND TRUST 2026-09-01 2025-12-15 <b>Emerging Markets Risk. </b>Investment in emerging market securities involves greater risk than that associated with investment in securities of issuers in developed foreign countries. These risks include volatile currency exchange rates, periods of high inflation, increased risk of default, greater social, economic and political uncertainty and instability, less governmental supervision and regulation of securities markets, weaker auditing and financial reporting standards, lack of liquidity in the markets, and the significantly smaller market capitalizations of emerging market issuers. The information available of an emerging market issuer may be less reliable than for comparable issuers in more developed capital markets. In addition, investments in certain emerging markets are subject to an elevated risk of loss resulting from market manipulation and the imposition of exchange controls (including repatriation restrictions). The legal rights and remedies available for investors in emerging markets may be more limited than the rights and remedies available in the U.S., and the ability of U.S. authorities (e.g., SEC and the U.S. Department of Justice) to bring actions against bad actors in emerging markets may be limited. The Adviser considers "emerging markets" to include countries in the MSCI Emerging Markets Index or countries that the Adviser considers to be emerging markets based on an evaluation of their level of economic development or the size and experience of their securities markets. <b>Foreign Securities Risk. </b>International investing may be subject to special risks, including, but not limited to, currency exchange rate volatility, political, social or economic instability, less publicly available information, less stringent investor protections, and differences in taxation, auditing and other financial practices. Foreign securities in which the Fund invests may be traded in markets that close before the time that the Fund calculates its NAV. Furthermore, certain foreign securities in which the Fund invests may be listed on foreign exchanges that trade on weekends or other days when the Fund does not calculate its NAV. As a result, the value of the Fund's holdings may change on days when shareholders are not able to purchase or redeem the Fund's shares.