August 26, 2021 Guardian Capital Fundamental Global Equity Fund Institutional Shares – GFGEX A Series of Capitol Series Trust (the “Trust”) Supplement to the Prospectus and Statement of Additional Information, Each Dated January 28, 2021 The Prospectus and Statement of Additional Information (“SAI”), each dated January 28, 2021, of the Guardian Capital Fundamental Global Equity Fund (the “Fund”) is hereby amended to reflect the updated information that follows. Special Meeting of Shareholders At a meeting of the Board of Trustees (the “Board”) of Capitol Series Trust (the “Trust”) held on June 17, 2021, the Board approved a new investment advisory agreement (“New Advisory Agreement”) between Guardian Capital LP (“Guardian Capital” or the “New Adviser”) and the Trust on behalf of the Fund, to take effect upon approval by shareholders of the Fund. Guardian Capital is a Toronto, Canada limited partnership which itself is a wholly-owned subsidiary of Guardian Capital Group Limited, a publicly traded firm listed on the Toronto Stock Exchange (“Guardian Ltd.”), and is registered with the U.S. Securities and Exchange Commission (“SEC”) as an investment adviser. In addition, at the same meeting held on June 17, 2021, the Board approved a new investment sub-advisory agreement as it relates to the Fund (the “New Sub-Advisory Agreement”) between Guardian Capital and GuardCap Asset Management Limited (“GuardCap”), a wholly-owned subsidiary of Guardian Capital domiciled in the United Kingdom and registered as an adviser with the SEC. The Fund’s current investment adviser, Alta Capital Management, LLC (“Alta”), is an indirect, majority-owned subsidiary of Guardian Capital. Alta has historically managed the Fund through a “participating affiliate” arrangement pursuant to which Alta has utilized GuardCap’s advisory personnel and resources to manage the Fund’s investments. The advisory and sub-advisory changes that Guardian Capital is proposing with respect to the Fund are part of an overall restructuring and rebranding of Guardian Capital’s U.S. mutual fund business. Guardian Capital is seeking to create a product lineup of U.S. mutual funds that: (1) are consistently branded across all of the funds; (2) have streamlined, consistent, and standardized internal processes and procedures in areas such as trading, compliance, finance, and legal oversight; (3) are generally structured as single adviser funds with Guardian Capital serving as the investment adviser or as sub-advised funds, with Guardian Capital, as the sponsor of the Guardian Capital fund family, serving as the investment adviser and its affiliated advisory entities serving as sub-adviser; and (4) have a commonality of fiscal year ends so that the all of the Guardian Capital Funds can be offered in a single prospectus. A special meeting of shareholders to consider the approval of the New Advisory Agreement and New Sub-Advisory Agreement is expected to occur on or about October 14, 2021. No changes are planned to the portfolio management team or investment approach for the Fund. The Fund’s daily operations and investment activities are not expected to be affected in any way. Additionally, under the New Advisory Agreement, there will be no increase in any fees or expenses that the Fund pays as a result of the change in advisory relationship. PLEASE RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE. Further Information For further information, please contact the Fund toll-free at 1-800-957-0681. You may also obtain additional copies of the Fund’s Prospectus and SAI, free of charge, by writing to the Fund c/o Ultimus Fund Solutions, LLC at P.O. Box 46707, Cincinnati, Ohio 45246-0707, by calling the Fund toll-free at the number above or by visiting the Fund’s website at www.altacapitalfunds.com. Investors Should Retain this Supplement for Future Reference. July 23, 2021 Guardian Fundamental Global Equity Fund Institutional Shares – GFGEX A Series of Capitol Series Trust (the “Trust”) Supplement to the Prospectus and Statement of Additional Information, Each Dated January 28, 2021 The Prospectus and Statement of Additional Information (“SAI”), each dated January 28, 2021, of the Guardian Fundamental Global Equity Fund (the “Fund”) is hereby amended to reflect the updated information that follows. Effective August 23, 2021, the Fund’s name will change to the Guardian Capital Fundamental Global Equity Fund. Accordingly, all references to the Fund’s name in its Prospectus and SAI shall reflect “Guardian Capital Fundamental Global Equity Fund.” Further Information For further information, please contact the Fund toll-free at 1-800-957-0681. You may also obtain additional copies of the Fund’s Prospectus and SAI, free of charge, by writing to the Fund c/o Ultimus Fund Solutions, LLC at P.O. Box 46707, Cincinnati, Ohio 45246-0707, by calling the Fund toll-free at the number above or by visiting the Fund’s website at www.altacapitalfunds.com. Investors Should Retain this Supplement for Future Reference. Guardian Fundamental Global Equity Fund Institutional Shares – GFGEX PROSPECTUS January 28, 2021 Alta Capital Management, LLC 6440 South Wasatch Boulevard, Suite 260 Salt Lake City, Utah 84121 Telephone: 1-800-957-0681 The U.S. Securities and Exchange Commission (“SEC”) has not approved or disapproved these securities or passed upon the adequacy or accuracy of this Prospectus. Any representation to the contrary is a criminal offense. The Prospectus gives you important information about the fund that you should know before you invest. Please read this Prospectus carefully before investing and use it for future reference. Beginning on January 1, 2021, as permitted by regulations adopted by the SEC, paper copies of the Guardian Fundamental Global Equity Fund’s (the “Fund”) shareholder reports will no longer be sent by mail, unless you specifically request paper copies of the reports from the Fund or from your financial intermediary such as a broker-dealer or bank. Instead, the reports will be made available on a website, and you will be notified by mail each time a report is posted and provided with a website link to access the report. If you already elected to receive shareholder reports electronically, you will not be affected by this change and you need not take any action. You may elect to receive shareholder reports and other communications from the Fund electronically by contacting the Fund at 1-800-957-0681 or, if you own any shares through a financial intermediary, by contacting your financial intermediary. You may elect to receive all future reports in paper free of charge. You can inform the Fund that you wish to continue receiving paper copies of your shareholder reports by contacting the Fund at 1-800-957-0681. If you own shares through a financial intermediary, you may contact your financial intermediary or follow instructions included with this document to elect to continue to receive paper copies of your shareholder reports. Your election to receive reports in paper will apply to all funds held with the fund complex or at your financial intermediary. Not A Deposit • Not FDIC Insured • May Lose Value • No Bank Guarantee • Not Insured By Any Government Agency TABLE OF CONTENTS Summary Section ...................................................................................................... 1 Investment Objective .................................................................................................. 1 Fees and Expenses of the Fund ���������������������������������������������������������������������������������� 1 Principal Investment Strategies .................................................................................. 2 Principal Investment Risks ......................................................................................... 3 Performance ................................................................................................................ 6 Portfolio Management ................................................................................................ 7 Purchases, Sales and Exchanges of Fund Shares .................................................. 8 Tax Information .......................................................................................................... 8 Payments to Brokers-Dealers and Other Financial Intermediaries ............................ 9 Additional Information Regarding Principal Investment Strategies .................. 10 Overview of Fund ....................................................................................................... 10 Investment Process ����������������������������������������������������������������������������������������������������� 11 Temporary Defensive Position ................................................................................... 12 Portfolio Holdings Information .................................................................................. 13 Investment Objective Updates .................................................................................... 13 Additional Information Regarding Principal Investment Risks .......................... 13 Account Information ................................................................................................ 18 Determination of Net Asset Value ........................................................................... 27 Dividends, Distributions, and Taxes ........................................................................ 28 Additional Information about Management of the Fund ....................................