Washington, D.C. 20549 Form 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2023 United States Securities and Exchange Commission DIAMOND HILL INVESTMENT GROUP, INC. (Exact name of registrant as specified in its charter) (State of incorporation) OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number 000-24498 Title ...