Form 485BXT RBB FUND, INC.

EXPLANATORY NOTE

Designation of New Effective Date for Previously Filed Post-Effective Amendment

Post-Effective Amendment No. 353 (the “Amendment”) was filed pursuant to Rule 485(a)(2) under the Securities Act of 1933, as amended (the “1933 Act”), on May 28, 2025 and pursuant to Rule 485(a)(2) would have become effective on August 11, 2025.

Post-Effective Amendment No. 361 was filed pursuant to Rule 485(b)(1)(iii) under the 1933 Act on August 8, 2025 for the sole purpose of extending the date upon which the Amendment was to become effective to September 10, 2025 with respect to F/m Compoundr Total Return Bond ETF, F/m Compoundr AAA CLO ETF, and F/m Compoundr Investment Grade Bond ETF (each a “Fund” and together, the “Funds”), each a series of the Registrant.

Post-Effective Amendment No. 364 was filed pursuant to Rule 485(b)(1)(iii) under the 1933 Act on September 9, 2025 for the sole purpose of extending the date upon which the Amendment was to become effective to October 10, 2025 with respect to the Funds.

Post-Effective Amendment No. 369 was filed pursuant to Rule 485(b)(1)(iii) under the 1933 Act on October 9, 2025 for the sole purpose of extending the date upon which the Amendment was to become effective to November 7, 2025 with respect to the Funds.

Post-Effective Amendment No. 372 was filed pursuant to Rule 485(b)(1)(iii) under the 1933 Act on November 6, 2025 for the sole purpose of extending the date upon which the Amendment was to become effective to December 5, 2025 with respect to the Funds.

Post-Effective Amendment No. 377 was filed pursuant to Rule 485(b)(1)(iii) under the 1933 Act on December 4, 2025 for the sole purpose of extending the date upon which the Amendment was to become effective to December 31, 2025 with respect to the Funds.

This Post-Effective Amendment No. 380 is being filed pursuant to Rule 485(b)(1)(iii) under the 1933 Act for the sole purpose of designating January 30, 2026 as the new date upon which the Amendment shall become effective with respect to the Funds.

This Post-Effective Amendment No. 380 incorporates by reference the information contained in Parts A, B and C of the Amendment with respect to the Funds.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended (the “1933 Act”), and the Investment Company Act of 1940, as amended, the Registrant certifies that it meets all of the requirements for effectiveness of this Post-Effective Amendment to its Registration Statement under Rule 485(b) under the 1933 Act and has duly caused this Post-Effective Amendment to its Registration Statement to be signed on its behalf by the undersigned, thereto duly authorized, in the City of Short Hills and State of New Jersey on the 30^th day of December, 2025.

Pursuant to the requirements of the 1933 Act, this Amendment to Registrant’s Registration Statement has been signed below by the following persons in the capacities and on the date indicated.

THE RBB FUND, INC.

(the “Company”)

THE RBB FUND TRUST

(the “Trust”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Gregory P. Chandler, hereby constitutes and appoints Jillian L. Bosmann, Edward Paz, Steven Plump, and James G. Shaw his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director/Trustee or officer, or both, of the Company and of the Trust, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the U.S. Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

THE RBB FUND, INC.

(the “Company”)

THE RBB FUND TRUST

(the “Trust”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Lisa A. Dolly, hereby constitutes and appoints Jillian L. Bosmann, Edward Paz, Steven Plump, and James G. Shaw her true and lawful attorneys, to execute in her name, place, and stead, in her capacity as Director/Trustee or officer, or both, of the Company and of the Trust, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the U.S. Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in her name and on her behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as she might or could do in person, said acts of said attorneys being hereby ratified and approved.

THE RBB FUND, INC.

(the “Company”)

THE RBB FUND TRUST

(the “Trust”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Nicholas A. Giordano, hereby constitutes and appoints Jillian L. Bosmann, Edward Paz, Steven Plump, and James G. Shaw his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director/Trustee or officer, or both, of the Company and of the Trust, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the U.S. Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

THE RBB FUND, INC.

(the “Company”)

THE RBB FUND TRUST

(the “Trust”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Arnold M. Reichman, hereby constitutes and appoints Jillian L. Bosmann, Edward Paz, Steven Plump, and James G. Shaw his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director/Trustee or officer, or both, of the Company and of the Trust, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the U.S. Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

THE RBB FUND, INC.

(the “Company”)

THE RBB FUND TRUST

(the “Trust”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Robert Sablowsky, hereby constitutes and appoints Jillian L. Bosmann, Edward Paz, Steven Plump, and James G. Shaw his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director/Trustee or officer, or both, of the Company and of the Trust, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the U.S. Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

THE RBB FUND, INC.

(the “Company”)

THE RBB FUND TRUST

(the “Trust”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Brian T. Shea, hereby constitutes and appoints Jillian L. Bosmann, Edward Paz, Steven Plump, and James G. Shaw his true and lawful attorneys, to execute in his name, place, and stead, in his capacity as Director/Trustee or officer, or both, of the Company and of the Trust, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the U.S. Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in his name and on his behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as he might or could do in person, said acts of said attorneys being hereby ratified and approved.

THE RBB FUND, INC.

(the “Company”)

THE RBB FUND TRUST

(the “Trust”)

POWER OF ATTORNEY

Know All Men by These Presents, that the undersigned, Martha A. Tirinnanzi, hereby constitutes and appoints Jillian L. Bosmann, Edward Paz, Steven Plump, and James G. Shaw her true and lawful attorneys, to execute in her name, place, and stead, in her capacity as Director/Trustee or officer, or both, of the Company and of the Trust, the Registration Statement and any amendments thereto and all instruments necessary or incidental in connection therewith, and to file the same with the U.S. Securities and Exchange Commission; and said attorneys shall have full power and authority to do and perform in her name and on her behalf, in any and all capacities, every act whatsoever requisite or necessary to be done in the premises, as fully and to all intents and purposes as she might or could do in person, said acts of said attorneys being hereby ratified and approved.