THE RBB FUND, INC. 

Abbey Capital Multi Asset Fund (the “Fund”)

Class I Shares (Ticker: MAFIX)

Class A Shares (Ticker: MAFAX)

Class C Shares (Ticker: MAFCX)

Supplement dated March 5, 2024
to the Fund’s Prospectus dated December 31, 2023

THIS SUPPLEMENT CONTAINS NEW AND ADDITIONAL INFORMATION BEYOND THAT CONTAINED IN THE PROSPECTUS AND STATEMENT OF ADDITIONAL INFORMATION (“SAI”) AND SHOULD BE READ IN CONJUNCTION WITH THE PROSPECTUS AND SAI.

The Fund’s Appendix A is deleted and replaced with the following:

APPENDIX A

THE INFORMATION ENCLOSED IN THIS APPENDIX IS PART OF, AND INCORPORATED IN, THE ABBEY CAPITAL MULTI ASSET FUND’S PROSPECTUS DATED DECEMBER 31, 2023.

WAIVERS AND DISCOUNTS AVAILABLE FROM SERVICE ORGANIZATIONS

The availability of certain sales charge waivers and discounts will depend on whether you purchase your shares directly from the Fund or through a Service Organization. Service Organizations may have different policies and procedures regarding the availability of front-end sales charge waivers or contingent deferred (back-end) sales charge (“CDSC”) waivers, which are discussed below.

In all instances, it is the purchaser’s responsibility to notify the Fund or the purchaser’s Service Organization at the time of purchase of any relationship or other facts qualifying the purchaser for sales charge waivers or discounts. Some waivers and discounts may not be made available through a particular Service Organization, and shareholders will have to purchase Shares directly from the Fund or through another Service Organization to receive these waivers or discounts.

MERRILL LYNCH

Purchases or sales of front-end (i.e. Class A) or level-load (i.e., Class C) mutual fund shares through a Merrill platform or account will be eligible only for the following sales load waivers (front-end, contingent deferred, or back-end waivers) and discounts, which differ from those disclosed elsewhere in this Fund’s prospectus. Purchasers will have to buy mutual fund shares directly from the mutual fund company or through another intermediary to be eligible for waivers or discounts not listed below.

It is the client’s responsibility to notify Merrill at the time of purchase or sale of any relationship or other facts that qualify the transaction for a waiver or discount. A Merrill representative may ask for reasonable documentation of such facts and Merrill may condition the granting of a waiver or discount on the timely receipt of such documentation.

Additional information on waivers and discounts is available in the Merrill Sales Load Waiver and Discounts Supplement (the “Merrill SLWD Supplement") and in the Mutual Fund Investing at Merrill pamphlet at ml.com/funds. Clients are encouraged to review these documents and speak with their financial advisor to determine whether a transaction is eligible for a waiver or discount.

Front-end Load Waivers Available at Merrill

Shares of mutual funds available for purchase by employer-sponsored retirement, deferred compensation, and employee benefit plans (including health savings accounts) and trusts used to fund those plans provided the shares are not held in a commission-based brokerage account and shares are held for the benefit of the plan. For purposes of this provision, employer-sponsored retirement plans do not include SEP IRAs, Simple IRAs, SAR-SEPs or Keogh plans

Shares purchased through a Merrill investment advisory program

Brokerage class shares exchanged from advisory class shares due to the holdings moving from a Merrill investment advisory program to a Merrill brokerage account

Shares purchased through the Merrill Edge Self-Directed platform

Shares purchased through the systematic reinvestment of capital gains distributions and dividend reinvestment when purchasing shares of the same mutual fund in the same account

Shares exchanged from level-load shares to front-end load shares of the same mutual fund in accordance with the description in the Merrill SLWD Supplement

Shares purchased by eligible employees of Merrill or its affiliates and their family members who purchase shares in accounts within the employee’s Merrill Household (as defined in the Merrill SLWD Supplement)

Shares purchased by eligible persons associated with the fund as defined in this prospectus (e.g. the fund’s officers or trustees)

Shares purchased from the proceeds of a mutual fund redemption in front-end load shares provided (1) the repurchase is in a mutual fund within the same fund family; (2) the repurchase occurs within 90 calendar days from the redemption trade date, and (3) the redemption and purchase occur in the same account (known as Rights of Reinstatement). Automated transactions (i.e. systematic purchases and withdrawals) and purchases made after shares are automatically sold to pay Merrill’s account maintenance fees are not eligible for Rights of Reinstatement

Contingent Deferred Sales Charge ("CDSC") Waivers on Front-end,Back-end, and Level Load Shares Available at Merrill

Shares sold due to the client’s death or disability (as defined by Internal Revenue Code Section 22e(3))

Shares sold pursuant to a systematic withdrawal program subject to Merrill’s maximum systematic withdrawal limits as described in the Merrill SLWD Supplement

Shares sold due to return of excess contributions from an IRA account

Shares sold as part of a required minimum distribution for IRA and retirement accounts due to the investor reaching the qualified age based on applicable IRS regulation

Front-end or level-load shares held in commission-based, non-taxable retirement brokerage accounts (e.g. traditional, Roth, rollover, SEP IRAs, Simple IRAs, SAR-SEPs or Keogh plans) that are transferred to fee-based accounts or platforms and exchanged for a lower cost share class of the same mutual fund

Front-end load Discounts Available at Merrill:

Breakpoints, Rights of Accumulation & Letters of Intent

Breakpoint discounts, as described in this prospectus, where the sales load is at or below the maximum sales load that Merrill permits to be assessed to a front-end load purchase, as described in the Merrill SLWD Supplement

Rights of Accumulation (ROA), as described in the Merrill SLWD Supplement, which entitle clients to breakpoint discounts based on the aggregated holdings of mutual fund family assets held in accounts in their Merrill Household

Letters of Intent (LOI), which allow for breakpoint discounts on eligible new purchases based on anticipated future eligible purchases within a fund family at Merrill, in accounts within your Merrill Household, as further described in the Merrill SLWD Supplement

MORGAN STANLEY WEALTH MANAGEMENT

Effective as of January 30, 2024, shareholders purchasing Fund Shares through a Morgan Stanley Wealth Management (“Morgan Stanley”) transactional brokerage account will be eligible only for the following front-end sales charge waivers with respect to Class A Shares, which may differ from and may be more limited than those disclosed elsewhere in this Fund’s Prospectus or SAI.

FRONT-END SALES CHARGE WAIVERS ON CLASS A SHARES AVAILABLE AT MORGAN STANLEY WEALTH MANAGEMENT

• Employer-sponsored retirement plans (e.g., 401(k) plans, 457 plans, employer-sponsored 403(b) plans, profit sharing and money purchase pension plans and defined benefit plans). For purposes of this provision, employer-sponsored retirement plans do not include SEP IRAs, Simple IRAs, SAR-SEPs or Keogh plans.

• Morgan Stanley employee and employee-related accounts according to Morgan Stanley’s account linking rules.

• Shares purchased through reinvestment of dividends and capital gains distributions when purchasing shares of the same fund.

• Shares purchased through a Morgan Stanley self-directed brokerage account.

• Class C (i.e., level-load) Shares that are no longer subject to a contingent deferred sales charge and are converted to Class A Shares of the same fund pursuant to Morgan Stanley Wealth Management’s share class conversion program.

• Shares purchased from the proceeds of redemptions within the same fund family, provided (i) the repurchase occurs within 90 days following the redemption, (ii) the redemption and purchase occur in the same account, and (iii) redeemed shares were subject to a front-end or deferred sales charge.

Please Retain this Supplement for future reference.