Dear Fellow Shareholders:

“InAt Diamond Hill, we are fiercely committed to improving the long run, deliveringlives of our clients and those they serve through the pursuit of exceptional investment results. Doing so requires discipline, patience, and a passion for what we do and who we serve. That passion drives us to develop outstanding, long-term partnerships with our clients because we know that excellent investment returnsoutcomes enable them to achieve their goals.

Achieving our long-term goals in an industry where change is constant can be challenging, especially when active managers continue to face several significant industry headwinds. Passive has been on the rise for our clients will helpdecades — as of year-end 2023, assets in passive funds and ETFs surpassed their active counterparts. Against this backdrop, new funds launched have struggled to generate growthgain traction with only a small number reaching scale within five years. Pairing this trend with increased demand for private assets in our businessthe institutional space and attract new clients and additional investments for us to manage.” That sentence opened our letter to shareholders over a decade ago and continuesincreasingly in retail, traditional active managers continue to be squeezed from both sides.

As we look ahead, we understand the headwinds in front of us, and given our primary business mindset today. Servingcompetitive advantages and our clientsdiscipline to stay focused, we believe we are positioned well for long-term success. To succeed in this challenging environment over the long term, we must take market share from our competitors by delivering long-term outperformance and an exceptional client experience that differentiates us. On balance, investors are allocating more to passive products as well as to private equities and credit. Many of our competitors have pursued aggressive acquisition strategies to shift their businesses to meet that demand. The reality is the keythat publicly traded active equity and fixed income are enormous categories that aren’t going anywhere anytime soon. In our view, this environment presents opportunities for those focused on actively managing concentrated portfolios with a valuation discipline and long-term ownership mindset. As such, we remain committed to continued success for the various constituencies of Diamond Hill.

It’s important to remember investors in passive products face higher investment risks than ever before. A handful of companies are now dominating US equity markets, exacerbating the already highly concentrated nature of returns. The tech-centric Magnificent 7 — Apple, Microsoft, Amazon, Alphabet, Nvidia, Meta and Tesla — accounted for more than half of 2023’s returns for index-based products tracking large-cap US equities. Passive strategies, by definition, do not come with the long-term analysis or portfolio oversight of their actively managed counterparts. The winning investments become an even greater share of the index, further tilting toward added risk. Investors have been willing to make that trade-off in strong market environments, and time will tell if this imbalance is sustainable. We are convinced that active management remains an essential component of investors’ success in the long run.

Instead of pursuing passive or private markets, as always, we remain focused on our strengths and prioritize areas where we have a majoritycompetitive edge. While we know it will take dedication and resilience to succeed in the active strategies we’ve built our business on, fewer firms focused on this particular arena should further enable us to continue adding value for our clients and shareholders.

We upgraded our distribution and marketing technologies and processes over the past five years to enhance the client experience. We built a new marketing function equipped with state-of-the-art data and analytics, and we launched a new visual identity for our brand. We also substantially advanced our adoption of technologies to nurture collaboration and connection — with an eye on delivering an employee experience that attracts and retains top talent. To ensure we can effectively execute and deliver on all of our long-term partnersstrategic initiatives going forward, we elevated Jo Ann Quinif to president of Diamond Hill Capital Management, increasing her responsibility for additional parts of our business that align with ensuring a great client experience.

We reached a significant milestone in our fixed income strategies in 2023 — assets across our fixed income strategies surpassed the $3 billion mark. As of 29 February 2024, our fixed income assets exceeded $3.9 billion. We have benefited from both strong market tailwindsmade significant investments to diversify our business and grow our assets, and we are pleased to see progress in this critical asset class.

In late 2023 and early 2024, we looked deeply at our operating model to assess our preparedness for the future. We believe modernizing our operating model — and understanding how the industry is changing and the impact it will have on our business — is necessary to succeed in a world increasingly driven by data and technology. Our key conclusions are that many aspects of our business serve us sufficiently today and don't need immediate change. However, there are a few areas, such as our client reporting and research management systems, as well as our active approach to data architecture and governance, that we are looking to optimize over the management ofnext two years to set us up for future success.

We believe our clients choose to work with us for our investment expertise and client-centric approach. We will continue proactively seeking to offer strategies in the vehicles our clients demand and improving our ability to customize strategies to meet their capital. Additionally, the team at Diamond Hill is working diligentlyneeds.

As we continue to improve all aspects ofevolve our business and I believepursue these operational goals, there are fundamental elements of who we are progressing inas a company that will not change. Our investment principles have always been, and will always be, the foundation of who we are and how we invest. Our fundamental commitment to prioritizing client interests is a constant that forms our identity and differentiates us from others. Our core competencies focus on delivering actively managed, concentrated, long-term-oriented strategies within US and international equity and fixed income. We will remain focused on areas where we have a competitive advantage and can offer differentiated solutions.

Diamond Hill has undergone many key areas. Attractingchanges since its inception. Throughout these changes, we have remained a client-centric, investment-led boutique that prioritizes a strong culture and retaining highly skilled people, effectively partnering withaspires to be a great workplace. We are confident this approach will continue serving our clients and continuing to operate our business in a highly efficient manner are criticalshareholders well.

Equity and ongoing pieces of building and sustaining an outstanding asset management organization. We are keenly focused on each of those essential organizational attributes.

So, while we ended the year with total assets under management (AUM) and 2)assets under advisement (AUA) of $29.2 billion, our average during the abilityyear was $27.3 billion, down 8% from 2022. Additionally, our mix of assets changed, partly due to identify new investment opportunities outsidefixed income inflows of $1.4 billion and equity outflows of $1.9 billion. Fixed income assets, which typically have lower fee rates, made up 14% of our AUM at the end of the U.S.year, an increase from 9% a year earlier. We recognize the impact on our business from net flows in 2023, but we are pleased with the enhanced knowledge base, increased idea generation, and the potential to serve clients interestedprogress we are making in strategies that include international securities.adding fixed income assets.

While 2023 was a challenging year, we focus on the long term in evaluating our largest expense isresults. From that perspective, we ended the compensationyear more positively than it began. The late-year rally boosted our ending AUM and AUA above $29 billion, more than $2.5 billion higher than where we started the year. Additionally, the strong market returns generated $23 million in investment

income in 2023. Our net income attributable to common shareholders was $42.2 million, up from $40.4 million in 2022, and our associates. Included in this line item is a significant amount of variable incentive compensation, which can fluctuate from year to year. A variety of factors influence incentive compensation including the investment results generated for our clients, individual employee contributions, and overall Company performance.

We may repurchase shares when they are interested in buying at a discount totrading below our estimate of fairthe firm’s intrinsic value. Since we began repurchasing shares in 2018, we have repurchased approximately 954,000 shares totaling $146 million, representing approximately 27% of our shares outstanding when we initiated our repurchases. Those repurchases have been partially offset by the net issuance of approximately 245,000 shares in the form of compensation to our associates over that period. We believe share-based compensation is a meaningful way to align our interests with shareholders. Since 2018, we have reduced our total share count by 711,000 shares, or 20%. Share repurchases in 2023 were approximately 213,000 shares, totaling $34.6 million.

While Jim Laird will continue as a board member through the end of his term in 2025, effective February 29, 2024, he has stepped down from his role as chairman. We are grateful to Jim for his leadership over the years and his many contributions to our success, first as Diamond Hill’s chief financial officer and president of Diamond Hill Funds from 2001 to 2014, as a director on our board since 2011 and as chairman since 2019.

We believe the best way to generate strong long-term shareholder returns is to deliver excellent investment outcomes for our clients. Our investment team is intensely focused on generating alpha for our clients, and our entire firm is committed to developing and maintaining partnerships that help instill the confidence required to remain invested through complete market cycles. This perspective has grown significantly since its founding in the Spring of 2000. An experienced and highly skilled team finding and serving well-aligned clients has been at the heart of that success. Prospectively, we intend to continue our history of operating efficiently and investing in outstanding people that allowenabled us to meetgrow new and existing client relationships, which ultimately helps us deliver returns to our fiduciary duty to clients.  Accomplishing that critical task will generate continued growth and value creation for all stakeholders.shareholders.

Action may be taken on the foregoing proposals at the Annual Meeting or at any postponement or adjournment of the Annual Meeting. The Board of Directors has fixed the close of business on March 5, 2018,11, 2024, as the record date for determining the shareholders entitled to vote at the Annual Meeting and any postponements or adjournments thereof. Please complete, signOn or about March 25, 2024, the Company began mailing to shareholders of record as of the close of business on March 11, 2024, the accompanying Proxy Statement, the form of proxy (also known as a proxy card), and date the enclosed proxy card, which is solicited by the Company’s Board of Directors, and mail it promptly in the enclosed envelope. Alternatively, you may vote by phone or electronically over the Internet in accordance with the instructions on the enclosed proxy card. Returning the enclosed proxy card, or transmitting voting instructions electronically through the Internet or by telephone, does not affect your right2023 Annual Report to vote in person at the Annual Meeting. If you attend the Annual Meeting you may revoke your proxy and vote in person if your shares are registered in your name.shareholders.

This Proxy Statement is being furnished to the shareholders of Diamond Hill Investment Group, Inc., an Ohio corporation (the “Company”, “we”, “us” or “our”), in connection with the solicitation of proxies by ourits Board of Directors (the “Board”) for use at our 2018its 2024 Annual Meeting of Shareholders (the “Annual Meeting”) to be held at Diamond Hill Investment Group, Inc., 325 John H. McConnell Boulevard, Suite 125, Columbus, Ohio 43215, at 10:00 a.m., Eastern Daylight Saving Time, on May 2, 2018,9, 2024, and any postponement or adjournment thereof. A copy of the Notice of Annual Meeting accompanies this Proxy Statement. This Proxy Statement and the enclosed form of proxy (also known as a proxy card) are first being mailed to shareholders on or about March 12, 2018.25, 2024. Only our shareholders of record at the close of business on March 5, 2018,11, 2024, the record date for the Annual Meeting, are entitled to notice of, and to vote at, the Annual Meeting.

The purposes of this Annual Meeting are:are to:

Only ourthe Company’s shareholders of record at the close of business on March 5, 2018,11, 2024, the record date, will be entitled to vote at the Annual Meeting. As of the record date, there were 3,509,577 of our common2,819,549 shares outstanding and entitled to be voted at the Annual Meeting.

Your shares will be voted at the Annual Meeting as you direct on your signed proxy card or in your telephonic or Internet voting instructions. If you are a record holder and submit a proxy card without voting instructions, it will be voted as recommended by the Board. If you are a beneficial owner, you have the right to direct your broker, bank, or other nominee on how to vote your shares, and you should contact your broker, bank, or other nominee to determine the procedures and deadlines that you must follow. The Board'sBoard’s recommendations are set forth in this Proxy Statement. The duly appointed proxy holders will vote in their discretion on any other matters that may properly come before the Annual Meeting.

Neither broker non-votes nor abstentions will have any effect on the election of directors. Abstentions will have the same effect as a vote againstdirectors, the ratification of the appointment of KPMG, andor the advisory approval of named executive officer compensation, but broker non-votes will have no effect on those proposals.2023 NEO compensation.

Business can be conducted at the Annual Meeting only if a quorum, consisting of at least the holders of at least a majority of ourthe Company’s outstanding shares entitled to vote, is present, either in person or by proxy. Abstentions and broker non-votes will be counted toward establishing a quorum. If a quorum is not present at the time the Annual Meeting is convened, a majority of the shares represented in person or by proxy may adjourn the Annual Meeting to a later date and time, without notice other than announcement at the Annual Meeting. At any such adjournment of the Annual Meeting at which a quorum is present, any business may be transacted which might have been transacted at the Annual Meeting as originally called.

No person is authorized to give any information or to make any representation not contained in this Proxy Statement, and you should not rely on any such information or representation. This Proxy Statement does not constitute the solicitation of a proxy in any jurisdiction from any person to whom it is unlawful to make such proxy solicitation in such jurisdiction. The delivery of this Proxy Statement shalldoes not, under any circumstances, imply that there has not been any change in the information set forth herein since the date of this Proxy Statement.

The following table sets forth beneficial ownership of ourthe Company’s shares of common shares as of the record date, March 5, 2018, bystock by: (a) all persons known by us to beneficially own five percent5% or more of the Company’s outstanding shares, (b) each director and director nominee of the Company, (c) our Chief Executive Officer, Chief Financial Officer, and Chief Operating Officer,the Company’s NEOs, and (d) all of ourthe Company’s executive officers, directors, and director nominees as a group. Although not required, we havethe Company has also voluntarily disclosed all shares of common sharesstock beneficially owned by all of its other employees, of the Company, excluding ourits executive officers. Unless otherwise indicated, the named persons exercise sole voting and dispositive power over the shares listed. None of the named persons hold any outstanding options to acquire ourCompany common shares,stock, and none of the named persons have pledged any common sharesstock of the Company as security. Except as otherwise indicated, all information is as of March 11, 2024.

In 2017, our shareholders adopted amendments to the Company's Amended and Restated Articles of Incorporation and Amended and Restated Code of Regulations to implement majority voting for the election of our directors. As a result of these amendments, in an uncontested election, a nominee will not be elected unless he or she receivesmust receive more “FOR” votes than “AGAINST” votes.votes to be elected. In addition, pursuant to the Board's Corporate Governance Guidelines, any director who fails to obtain the required vote in an uncontested election will be expected topromptly submit his or hertheir resignation to the Board. The Board will then decide, after considering the Nominating and Governance Committee'sCommittee’s recommendation, whether to accept orthe resignation, decline the resignation, or decline the resignation with conditions. The Board will make any such decision within 90 days following the Shareholderdate of the Annual meeting date.Meeting at which such uncontested election occurred. Plurality voting will apply to any contested elections.

The Board has determined that all of ourthe Company’s director nominees are qualified to serve as directors of the Company. In addition to thetheir specific business experience listed below, each of ourthe Company’s director nominees has the tangible and intangible skills and attributes that we believethe Board believes are required to be an effective director of the Company, including experience at senior levels in areas of expertise helpful to the Company, a willingness and commitment to assume the responsibilities required of a director, and the character and integrity we expectthat the Board expects of ourthe Company’s directors. The specific qualifications of each individual nominee are set forth under hissuch nominee’s name below.

Mr. Fortener receivedCooley holds Bachelor of the Arts and Master of the Arts degrees from Illinois State University, a BS in accounting from The UniversityMaster of Findlay and an MBA in financethe Arts degree from the University of DaytonChicago, and is a Certified Public Accountant (inactive).Doctor of Philosophy in Political Science from the University of Chicago. He was also awarded the Certificate in Cybersecurity Oversight from the Software Engineering Institute in association with Carnegie Mellon University in 2023.

Mr. Fortener’sCooley’s qualifications to serve on the Board include his substantial experience in accounting and financial matters includingdue to serving as CFO of a global, publicly-traded financial services firm, his significant experience as CEO of a certified public accountant anddivision of a large financial services firm, as well as his experience on other corporate boards.serving as a board member for numerous for-profit companies.

Mr. Laird received his BSBachelor of Science in Accounting from The Ohio State University, is a Certified Public Accountant (inactive), and previously held the Series 7, 24, 26, 27, and 63 securities licenses with the Financial Industry Regulatory Authority.

Mr. Laird’s qualifications to serve on the Board include his 13 years of experience as CFO of the Company, his in-depth knowledge of, and involvement in, ourthe Company’s operations and his more than 30 years of experience in the financial, operational, administrative, and distribution aspects of the investment management industry.

The Board held a total of four meetings during the year ended December 31, 2017. Each2023, and each director attended at least 75% of all of the meetings of theapplicable Board and its committees of which he or she was a member.committee meetings. Consistent with our Corporate Governancethe Guidelines and Nasdaq listing rules, the directors met in executive session at each regularly scheduled Board meeting in 2017. Our Corporate Governance2023. Although the Company does not have a formal policy requiring directors’ attendance at the Annual Meeting, the Guidelines provide that all directors are expected to attend each annual meeting of shareholders. All individuals serving as directors at the time of our then incumbent directors attended our 2017the 2023 Annual Meeting of Shareholders.Shareholders attended such meeting.

WeThe Company also havehas a Code of Business Conduct and Ethics that is applicable to all of ourits employees and directors, a copy of which was filed as an exhibit to our Annual Report on Form 10-K filed with the SEC on March 7, 2014.directors. It is ourthe Company’s policy to require all employees to participate annually in continuing education and training relatingrelated to the Code of Business Conduct and CodeEthics.

The Company has established a policy prohibiting our officers,its employees and directors and employees from purchasing or selling shares of the Company while in possession of material nonpublic information, or otherwise using such information for their personal benefit or in any manner that would violate applicable laws and regulations. The policy also prohibits all employees and directors from purchasing or selling any derivative arrangement related to securities of the Company or engaging in any speculative, short selling, or hedging activities related to securities of the Company that may have a similar economic effect.

Mr. Fortener, Mr. Laird (effective January 1, 2018), Mr. Reeder, and Mr. ShoupAll independent directors serve on the Audit Committee. The Audit Committee which met four times during 2017. Mr. Fortener serves as the Chair of the Audit Committee.2023. The Board has determined that each of these committeethe Audit Committee members meets the independence and financial literacy rules and standards of the SEC and NASDAQ.Nasdaq. The Board also has concluded that each of Mr. Fortener,Cooley, Mr. Laird, Mr. Reeder, and Mr. Shoup also meetsThomas meet the criteria to be an audit“audit committee financial expertexpert” as defined by the SEC. Ms. Skinner served on the Audit Committee until she resigned from the committee on April 26, 2017.

The primary purpose of the Audit Committee is to assist the Board in fulfilling its oversight responsibilities with respect toto: (i) the retention of ourthe Company’s independent registered public accounting firm, including appointing and overseeing the terms of itsthe accounting firm’s engagement and its performance, qualifications, and independence,independence; (ii) the quality and the integrity of ourthe Company’s financial statements, otherstatements; (iii) the Company’s accounting and financial information providedreporting process; (iv) adherence to shareholders,the Company’s ethics policies; and our(v) the Company’s systems for internal control structure.accounting and financial controls. The Audit Committee also reviews all related person transactions for potential conflicts of interest on an ongoing basis, and the Audit Committee must approve all such transactions must be approved by the Audit Committee.transactions. Additional information on the approval of related person transactions is available under the heading “Certain Relationships and Related Person Transactions” below. The report of the Audit Committee appears belowunder the heading “AUDIT COMMITTEE REPORT.”“Audit Committee Report” below.

Mr. Fortener, Mr. Laird (effective January 1, 2018), Mr. Reeder, and Mr. Shoup,All independent directors serve on the Compensation Committee. Mr. Laird serves as the Chair of theThe Compensation Committee.Committee met two times during 2023. The Board has determined that each of these committeethe Compensation Committee members meets the independence criteria of the SEC and NASDAQ. The Committee met two times during 2017. Ms. Skinner served as the Chair of the Compensation Committee until she resigned from the committee on July 26, 2017. Mr. Shoup served as the interim Chair of the Compensation Committee from July 27, 2017 to December 31, 2017.Nasdaq.

The primary purpose of the Compensation Committee is to assist the Board in the discharge of its responsibilities to: (i) review and approve the compensation and benefits programs of the Company’s executive compensation policies,NEOs and directors; (ii) evaluate the performance of ourthe Company’s executive officers in light of corporate goals and objectives approved by the Compensation Committee,Committee; (iii) approve the annual salaries, bonuses, stock grants, and other benefits, direct and indirect, of ourthe Company’s executive officers,officers; (iv) make recommendations to the full Board with respect to incentive compensation plans and equity-based plansplans; (v) appoint and oversee the work of compensation consultants and other advisors; (vi) determine director, committee member, and committee member/chair compensation for non-employee directors.directors; and (vii) oversee succession planning for the Company’s executive officers. The Compensation Committee also administers, ourmaintains, or delegates the administration and maintenance of the Company’s equity and other incentivecompensation plans. The Compensation Committee has delegated to management the ability to make stock grants to ournon-executive employees within specific parameters to align the interests of ourthe Company’s shareholders and ourits employees and to promote employee retention and long-term employee ownership. A description of the Company’s processes and procedures for the consideration and determination of executive officer compensation are discussed under the heading “Compensation Discussion and Analysis” below.

Mr. Fortener, Mr. Laird (effective January 1, 2018), Mr. Reeder, and Mr. ShoupAll independent directors serve on the Nominating and Governance Committee, which met twice during 2017. Mr. Shoup serves as the Chair of theCommittee. The Nominating and Governance Committee.Committee met four times during 2023. The Board has determined that each of these committeethe Nominating and Governance Committee members meets the independence criteria of NASDAQ. Ms. Skinner served on the Committee through December 31, 2017.SEC and Nasdaq.

The primary purpose of the Nominating and Governance Committee is to maintain and cultivate the effectiveness of the Board and oversee the Company’s governance policies. Among the committee’sNominating and Governance Committee’s responsibilities are Board and committee composition, director qualifications, director orientation and education, and Board, committee, and director evaluations. The Nominating and Governance CommitteeCommittee: (i) identifies, evaluates, and nominates Board candidates; (ii) develops and oversees Board leadership succession planning, (iii) reviews compliance with director stock ownership guidelines;guidelines for directors and NEOs; and (iv) oversees procedures regarding shareholder nominations and other shareholder communications to the Board. The Nominating and Governance Committee is also responsible for monitoring compliance with, and recommending any changes to, the Company’s Corporate Governance Guidelines. Additional information regarding the committee’s activities can be found under the heading “Corporate Governance.”Governance” below.

The following table summarizes the membership of the Board and each of its committees as of March 11, 2024, and the number of times each body met during 2017.2023.