THE RBB FUND, INC.

Campbell Systematic Macro Fund (the “Fund”)

Supplement dated May 20, 2025

to the Prospectus dated February 28, 2025

Effective June 1, 2025, the sales load structure for the Fund’s Class A Shares will be modified for purchases exceeding $250,000. Accordingly, please note the following:

The section entitled “Summary Section – Expenses and Fees” is amended and restated in its entirety as shown below:

Expenses and Fees

This table describes the fees and expenses that you may pay if you buy, hold and sell shares of the Fund (the "Shares"). You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you invest at least $25,000 in Class A Shares of the Fund. More information about these discounts is available from your financial professional, in the section of this Prospectus entitled “Shareholder Information – Sales Charges” and in the section of the Fund’s Statement of Additional Information (“SAI”) entitled “Purchase and Redemption Information – Reducing or Eliminating the Front End Sales Charge.” Financial Intermediaries may impose different sales charge waivers for Class A Shares, and these variations are described in the section of this Prospectus entitled “Shareholder – Information – Sales Charges”.


SHAREHOLDER FEES (fees paid directly from your investment)	Class A	Class I	Class C
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	3.50%	None	None
Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price)⁽¹⁾	None	None	1.00%


ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Management Fees	1.64%	1.64%	1.64%
Distribution and/or Service (12b-1) Fees⁽²⁾	0.25%	None	1.00%
Other Expenses	0.20%	0.20%	0.20%
Total Annual Fund Operating Expenses	2.09%	1.84%	2.84%
Fee Waivers and/or Expense Reimbursements⁽³⁾	-0.09%	-0.09%	-0.09%
Total Annual Fund Operating Expenses After Fee Waiver	2.00%	1.75%	2.75%

⁽¹⁾

A contingent deferred sales charge (“CDSC”) of 1.00% is assessed on redemptions of Class C shares made within twelve months after a purchase of Class C Shares.

⁽²⁾

The Fund has adopted a distribution plan for Class A Shares and Class C Shares pursuant to Rule 12b-1 (“Rule 12b-1 Plan”) under the Investment Company Act of 1940, as amended (the “1940 Act”) that permits payments of up to 0.25% as a percentage of average daily net assets of the Fund’s Class A Shares and payments of up to 1.00% as a percentage of average daily net assets of the Fund’s Class C Shares.

⁽³⁾

Campbell & Company Investment Adviser LLC ("Campbell" or the "Adviser") has contractually agreed to waive its advisory fee and/or reimburse expenses in order to limit Total Annual Fund Operating Expenses (excluding certain items discussed below) to 2.00%, 1.75%, and 2.75% of the Fund's average daily net assets for Class A Shares, Class I Shares, and Class C Shares, respectively. In determining the Adviser's obligation to waive advisory fees and/or reimburse expenses, the following expenses are not taken into account and could cause net Total Annual Fund Operating Expenses to exceed 2.00%, 1.75%, and 2.75%, as applicable: acquired fund fees and expenses, brokerage commissions, extraordinary items, interest or taxes. This contractual limitation is in effect until December 31, 2026 and may not be terminated without the approval of the Board of Directors of The RBB Fund, Inc. If at any time the Fund's Total Annual Fund Operating Expenses (not including acquired fund fees and expenses, brokerage commissions, extraordinary items, interest or taxes) for a year are less than 2.00%, 1.75%, and 2.75%, as applicable, the Adviser may recoup from the Fund any waived amount or other payments remitted by the Adviser within three years from the date on which such waiver or reimbursement was made, provided such reimbursement does not cause the Fund to exceed expense limitations that were in effect at the time of the waiver or reimbursement and the expense limitations that are current in effect.

The section entitled “Shareholder Information – Sales Charges – Class A Shares Sales Charges” is amended and restated in its entirety as shown below:

Class A Shares Sales Charges. Purchases of Class A Shares of the Fund are subject to a front-end sales charge of up to 3.50% of the total purchase price; however, sales charges may be reduced for large purchases as indicated below. Sales charges are not imposed on Shares that are purchased with reinvested dividends or other distributions. The table below indicates the front-end sales charge as a percentage of both the offering price and the net amount invested. The term “offering price” includes the front-end sales charge. Because of rounding in the calculation of the “offering price”, the actual sales charge you pay may be more or less than that calculated using the percentages shown below.

Amount of Purchase of Class A Shares	Sales Charge as a % of Offering Price	Sales Charge as a % of Net Amount Invested	Dealer Compensation as a Percentage of Offering Price
Less than $25,000	3.50%	3.63%	3.00%
At least $25,000 but less than $50,000	3.00%	3.09%	2.75%
At least $50,000 but less than $100,000	2.75%	2.83%	2.50%
At least $100,000 but less than $250,000	2.50%	2.56%	2.25%
At least $250,000 but less than $500,000	1.50%	1.52%	1.25%
At least $500,000 but less than $1,000,000	1.00%	1.01%	0.75%
$1,000,000 or greater	0.00%	0.00%	0.00%

You may qualify for reduced sales charges or sales charge waivers. If you believe that you may qualify for a reduction or waiver of the sales charge, you should discuss this matter with your broker or other financial intermediary. To qualify for these reductions or waivers, you or your financial intermediary must provide sufficient information at the time of purchase to verify that your purchase qualifies for such treatment. This information could be used to aggregate, for example, holdings in retirement accounts, Fund shares owned by your immediate family members, and holdings in accounts at other brokers or financial intermediaries. In addition to breakpoint discounts, the following sections describe other circumstances in which sales charges are waived or otherwise may be reduced. See “Reduced Sales Charges – Class A Shares” below.

The section entitled “Shareholder Information – Sales Charges – Contingent Deferred Sales Charge on Certain Redemptions – Class A Shares” is deleted.

Effective June 30, 2025, the mailing address for the Fund has changed. Going forward, please send written requests to obtain Fund documentation, or to purchase, redeem, or exchange shares of the Fund to:

	Regular Mail:	Overnight Delivery:

	Campbell Systematic Macro Fund	Campbell Systematic Macro Fund
	c/o U.S. Bank Global Fund Services	c/o U.S. Bank Global Fund Services
	PO Box 219252	801 Pennsylvania Avenue, Suite 219252
	Kansas City, MO 64121-9252	Kansas City, MO 64105-1307

If you have any questions, please call the Fund at 1-844-261-6488.

Investors should retain this supplement for future reference.

THE RBB FUND, INC.

Campbell Systematic Macro Fund (the “Fund”)

Supplement dated May 20, 2025

to the Statement of Additional Information dated February 28, 2025

Effective June 1, 2025, the sales load structure for the Fund’s Class A Shares will be modified for purchases exceeding $250,000.

Accordingly, the section entitled “Purchase and Redemption Information – Sales Charges – Class A Shares Sales Charges” is amended and restated in its entirety as shown below:

Class A Shares Sales Charges. Purchases of Class A Shares of the Fund are subject to a front-end sales charge of up to 3.50% of the total purchase price; however, sales charges may be reduced for large purchases as indicated below. For Class A Shares sold by the Distributor, the Distributor will receive the sales charge imposed on purchases of Class A Shares (or any contingent deferred sales charge paid on redemptions) and may retain the full amount of such sales charge. The sales charges or underwriter concessions (the difference between the sales charge and the dealer reallowance) received by the Distributor may be made available to the Fund for pre-approved marketing expenses or may be used to offset the compensation owed by the Adviser to the Distributor for its services. Sales charges are not imposed on Shares that are purchased with reinvested dividends or other distributions. The table below indicates the front-end sales charge as a percentage of both the offering price and the net amount invested. The term “offering price” includes the front-end sales charge. Because of rounding in the calculation of the “offering price”, the actual sales charge you pay may be more or less than that calculated using the percentages shown below.

Amount of Purchase of Class A Shares	Sales Charge as a % of Offering Price	Sales Charge as a % of Net Amount Invested	Dealer Compensation as a Percentage of Offering Price
Less than $25,000	3.50%	3.63%	3.00%
At least $25,000 but less than $50,000	3.00%	3.09%	2.75%
At least $50,000 but less than $100,000	2.75%	2.83%	2.50%
At least $100,000 but less than $250,000	2.50%	2.56%	2.25%
At least $250,000 but less than $500,000	1.50%	1.52%	1.25%
At least $500,000 but less than $1,000,000	1.00%	1.01%	0.75%
$1,000,000 or greater	0.00%	0.00%	0.00%

The section entitled “Purchase and Redemption Information – Sales Charges – Contingent Deferred Sales Charge on Certain Redemptions – Class A Shares” is deleted.

Regular Mail:

Campbell Systematic Macro Fund

c/o U.S. Bank Global Fund Services

PO Box 219252

Kansas City, MO 64121-9252

Overnight Delivery:

Campbell Systematic Macro Fund

c/o U.S. Bank Global Fund Services

801 Pennsylvania Avenue, Suite 219252

Kansas City, MO 64105-1307

If you have any questions, please call the Fund at 1-844-261-6488.

Investors should retain this supplement for future reference.