Material Event (Form 8-K)

On January 28, 2026, Diamond Hill Investment Group, Inc., an Ohio corporation (the "Company" or "Diamond Hill"), filed its definitive proxy statement on Schedule 14A (as such may be supplemented from time to time, the "Proxy Statement") with the Securities and Exchange Commission (the "SEC") with respect to the special meeting of the Company's shareholders (the "Special Meeting") to be held in connection with transactions contemplated by that certain Agreement and Plan of Merger (the "Merger Agreement"), dated as of December 10, 2025, by and among the Company, First Eagle Investment Management, LLC, a Delaware limited liability company ("Purchaser"), and Soar Christopher Holdings, Inc., an Ohio corporation and a wholly owned subsidiary of Purchaser ("Merger Sub"). Upon the terms and subject to the conditions set forth in the Merger Agreement, Merger Sub will merge with and into the Company (the "Merger"), whereupon the separate existence of Merger Sub will cease, and the Company will be the surviving corporation as a wholly-owned subsidiary of Purchaser.

The Special Meeting is scheduled for March 3, 2026, beginning at 10:00 a.m. Eastern Time. The Company's shareholders of record as of the close of business on January 27, 2026 will be eligible to vote at the Special Meeting. Subject to the satisfaction of the remaining conditions to the closing of the Merger under the Merger Agreement, including that the Company's shareholders vote to approve the Merger and the receipt of the requisite client consents based on revenue run-rate, the Company expects to complete the Merger in the second quarter of 2026.

Litigation Relating to the Merger

As of the date of this Form 8-K, two lawsuits relating to the Merger (collectively, the "Lawsuits") have been filed: (i) Connolly v. Diamond Hill Investment Group, Inc., et al. Index No. 650758/2026, which was filed in the Supreme Court of the State of New York, County of New York, on February 6, 2026 and (ii) Goggin v. Diamond Hill Investment Group, Inc., et al. Index No. 650754/2026, which was filed in the Supreme Court of the State of New York, County of New York, on February 5, 2026. The Lawsuits were each filed by a purported shareholder of the Company as an individual action and allege that the Proxy Statement was materially incomplete due to certain misrepresentations and omissions in violation of New York common law. The Lawsuits name as defendants the Company and its directors and seek, among other relief, an order enjoining the consummation of the Merger. There can be no assurance regarding the ultimate outcome of the Lawsuits.

As of the date of this Form 8-K, attorneys representing multiple purported shareholders of the Company have also delivered demand letters to the Company (collectively, the "Demand Letters") alleging that the disclosures contained in the Proxy Statement are deficient and requesting that the Company supplement such disclosures prior to the Special Meeting. The Demand Letters threaten the Company with lawsuits in the event that the purported deficiencies in the Proxy Statement are not addressed.

It is possible that additional, similar complaints may be filed, that the Lawsuits described above may be amended, or that additional demand letters will be received by the Company. If this occurs, the Company does not intend to announce the filing or receipt of each additional, similar complaint or demand letter or any amended complaint unless required by law.

The Company believes that the claims asserted in the Lawsuits and the Demand Letters are without merit. However, in order to moot the unmeritorious disclosure claims, alleviate the costs, risks and uncertainties inherent in potential litigation and provide additional information to its shareholders, the Company has determined to voluntarily supplement the Proxy Statement as described in this Form 8-K. Nothing in this Form 8-K shall be deemed an admission of the legal necessity or materiality under applicable laws of any of the disclosures set forth herein. To the contrary, the Company specifically denies all allegations set forth in the Lawsuits and the Demand Letters that any additional disclosure in the Proxy Statement was or is required.

Supplemental Disclosures

The following disclosures supplement the disclosures contained in the Proxy Statement and should be read in conjunction with the disclosures contained in the Proxy Statement, which should be read in its entirety. To the extent the information set forth herein differs from or updates information contained in the Proxy Statement, the information set forth herein shall supersede or supplement the information in the Proxy Statement. All page references are to pages in the Proxy Statement, and terms used below, unless otherwise defined, have the meanings set forth in the Proxy Statement.