As filed with the Securities and Exchange Commission on July 14, 2026

File Nos. 333-22075 and 811-08061

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT

UNDER

and/or

REGISTRATION STATEMENT

UNDER

Diamond Hill Funds

(Exact Name of Registrant as Specified in Charter)

325 John H. McConnell Blvd., Suite 200, Columbus, Ohio 43215

(Address of Principal Executive Offices) (Zip Code)

Registrant’s Telephone Number, including Area Code: (888) 226-5595

Sheelyn Michael, Diamond Hill Funds

325 John H. McConnell Blvd., Suite 200, Columbus, Ohio 43215

(Name and Address of Agent for Service)

With copy to:

Nathan J. Greene, Esq.

Sidley Austin LLP

787 Seventh Avenue

New York, NY 10019

Approximate Date of Proposed Public Offering:

It is proposed that this filing will become effective:

If appropriate, check the following box:

Contents of Post-Effective Amendment No.99

This Post-Effective Amendment to the Registration Statement comprises the following papers and contents:

The Facing Sheet

The sole purpose of this filing is to delay the effectiveness of the Registrant’s Post-Effective Amendment No. 94, as it relates to Diamond Hill High Income ETF (the “Fund”), a series of the Registrant, until August 13, 2026. Parts A and B of the Registrant’s Post-Effective Amendment No. 94, filed on February 6, 2026, are incorporated by reference herein. Part C of the Registrant’s Post-Effective Amendment No. 97, filed on May 18, 2026, is incorporated by reference herein.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended (the “Securities Act”), and the Investment Company Act of 1940, as amended, the Registrant certifies that it meets all of the requirements for effectiveness of this registration statement under Rule 485(b) under the Securities Act and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of New York, and the State of New York on July 14, 2026.

Pursuant to the requirements of the Securities Act, this Post-Effective Amendment to the registration statement has been signed below by the following persons in the capacities and on the dates indicated.