DHIL 10-Q Quarter ended June 30, 2012

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United States

Securities and Exchange Commission

Washington, D.C. 20549

Form 10-Q

QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF

THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended June 30, 2012

Commission file number 000-24498

DIAMOND HILL INVESTMENT GROUP, INC.

(Exact name of registrant as specified in its charter)

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

(Address, including Zip Code, of principal executive offices)

(614) 255-3333

(Registrant’s telephone number, including area code)

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months, and (2) has been subject to such filing requirements for the past 90 days.    Yes: x No: ¨

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    Yes x No ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

Large accelerated filer ¨ Accelerated filer x Non-accelerated filer ¨ Smaller reporting company ¨

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).    Yes: ¨ No: x

The number of shares outstanding of the issuer’s common stock, as of July 27, 2012, is 3,153,266 shares.

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DIAMOND HILL INVESTMENT GROUP, INC.

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Diamond Hill Investment Group, Inc.

The accompanying notes are an integral part of these consolidated financial statements.

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Diamond Hill Investment Group, Inc.

The accompanying notes are an integral part of these consolidated financial statements.

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Diamond Hill Investment Group, Inc.

The accompanying notes are an integral part of these consolidated financial statements.

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Diamond Hill Investment Group, Inc.

Notes to Consolidated Financial Statements (unaudited)

Diamond Hill Investment Group, Inc. (the “Company”) derives its consolidated revenues and net income primarily from investment advisory and fund administration services. The Company has four operating subsidiaries.

Diamond Hill Capital Management, Inc. (“DHCM”), an Ohio corporation, is a wholly owned subsidiary of the Company and a registered investment adviser. DHCM is the investment adviser to the Diamond Hill Funds (the “Funds”), a series of open-end mutual funds, private investment funds (“Private Funds”), and also offers advisory services to institutional and individual investors.

Diamond Hill GP (Cayman) Ltd. (“DHGP”) was incorporated in the Cayman Islands as an exempted company on May 18, 2006 for the purpose of acting as the general partner of a Cayman Islands exempted limited partnership. This limited partnership acts as a master fund for Diamond Hill Offshore Ltd., a Cayman Islands exempted company; and Diamond Hill Investment Partners II, L.P., an Ohio limited partnership. DHGP has no operating activity.

Beacon Hill Fund Services, Inc. (“BHFS”), an Ohio corporation, is a wholly owned subsidiary of the Company incorporated on January 29, 2008. BHFS provides certain compliance, treasury, and fund administration services to mutual fund companies. BHIL Distributors, Inc. (“BHIL”), an Ohio corporation, is a wholly owned subsidiary of BHFS incorporated on February 19, 2008. BHIL provides underwriting and distribution services to mutual fund companies. BHFS and BHIL collectively operate as Beacon Hill.

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the reported amounts of revenues and expenses for the periods. Actual results could differ from those estimates. Certain prior period amounts and disclosures have been reclassified to conform to the current period financial presentation. Book value per share is computed by dividing total shareholders’ equity by the number of shares issued and outstanding at the end of the measurement period. The following is a summary of the Company’s significant accounting policies:

Principles of Consolidation

The accompanying consolidated financial statements include the operations of the Company and its subsidiaries. All material inter-company transactions and balances have been eliminated in consolidation.

Segment Information

Management has determined that the Company operates in one business segment, namely providing investment management and administration services to mutual funds, separate accounts, and private investment funds. Therefore, no disclosures relating to operating segments are required in annual or interim financial statements.

Cash and Cash Equivalents

Cash and cash equivalents include demand deposits and money market mutual funds.

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Note 2 Significant Accounting Policies (Continued)

Accounts Receivable

Accounts receivable are recorded when they are due and are presented in the balance sheet, net of any allowance for doubtful accounts. Accounts receivable are written off when they are determined to be uncollectible. Any allowance for doubtful accounts is estimated based on the Company’s historical losses, existing conditions in the industry, and the financial stability of those individuals or entities that owe the receivable. No allowance for doubtful accounts was deemed necessary at June 30, 2012 or December 31, 2011.

Valuation of Investment Portfolio

Investments held by the Company are valued based upon the definition of Level 1 inputs and Level 2 inputs. Level 1 inputs are defined as fair values which use quoted prices in active markets for identical assets or liabilities that the Company has the ability to access. Level 2 inputs are defined as quoted prices in markets that are not considered to be active for identical assets or liabilities, quoted prices in active markets for similar assets or liabilities and inputs other than quoted prices that are directly observable or indirectly through corroboration with observable market data. The following table summarizes the Company’s investments valued based upon Level 1 and Level 2 inputs as of June 30, 2012 and December 31, 2011:

Level 1 investments are all registered investment companies (mutual funds) and include $10.6 million and $9.2 million, respectively, of money market mutual funds that the Company classifies as cash equivalents. Level 2 investments are all limited partnerships. There were no transfers in or out of the levels.

The changes in market values on the investments are recorded in the Consolidated Statements of Income as investment return.

Limited Partnership Interests

DHCM is the managing member of Diamond Hill General Partner, LLC, the General Partner of Diamond Hill Investment Partners, L.P. (“DHIP”), Diamond Hill Investment Partners II, L.P. (“DHIP II”), Diamond Hill Research Partners, L.P. (“DHRP”), Diamond Hill Research Partners – International, L.P. (“DHRPI”), and Diamond Hill Valuation-Based Index, L.P. (“DHBV”) collectively (the “Partnerships”), each a limited partnership whose underlying assets consist of marketable securities. Effective January 3, 2012, Diamond Hill Research Partners, L.P. converted to Diamond Hill Research Opportunities Fund, a series of the Diamond Hill Funds.

DHCM, in its role as managing member of the General Partner, has the power to direct the Partnerships’ economic activities and the right to receive investment advisory and performance incentive fees that are significant to the Partnerships. The Partnerships are subject to investment company accounting and, as a result, they have not been consolidated in presenting the accompanying financial statements. DHCM’s investments in these partnerships are reported as a component of the Company’s investment portfolio, valued at DHCM’s proportionate interest in the net asset value of the marketable securities held by the Partnerships. Gains and losses attributable to changes in the value of DHCM’s interests in the Partnerships are included in the Company’s reported investment return.

The Company’s exposure to loss as a result of its involvement with the Partnerships is limited to the amount of its investments. DHCM is not obligated to provide financial or other support to the Partnerships, other than its investments to date and its contractually provided investment advisory responsibilities, and has not provided such support. The Company has not provided liquidity arrangements, guarantees or other commitments to support the Partnerships’ operations, and the Partnerships’ creditors and interest holders have no recourse to the general credit of the Company.

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Note 2 Significant Accounting Policies (Continued)

Limited Partnership Interests (Continued)

Several board members, officers and employees of the Company invest in the DHIP through Diamond Hill General Partner, LLC. These individuals receive no remuneration as a result of their personal investment in the Partnerships. The capital of Diamond Hill General Partner, LLC is not subject to a management fee or an incentive fee.

Furniture and Equipment

Furniture and equipment, consisting of computer equipment, furniture, and fixtures, are carried at cost less accumulated depreciation. Depreciation is calculated using the straight-line method over estimated lives of three to seven years.

Revenue Recognition - General

The Company earns substantially all of its revenue from investment advisory and fund administration services. Mutual fund investment advisory and administration fees, generally calculated as a percentage of assets under management, are recorded as revenue as services are performed. Managed account and private investment fund clients provide for monthly or quarterly management fees, in addition to periodic variable incentive fees.

Revenue Recognition – Incentive Revenue

The Company manages certain client accounts that provide for variable incentive fees. These fees are based on investment results over rolling five year periods. For variable management fees based on a formula, there are two methods by which incentive revenue may be recorded. Under “Method 1”, incentive fees are recorded at the end of the contract measurement period; under “Method 2”, the incentive fees are recorded periodically and calculated as the amount that would be due under the formula at any point in time as if the contract was terminated at that date. Management has chosen Method 1, in which incentive fees are recorded at the end of the contract measurement period for the specific client in which the incentive fee applies. The table below shows assets under management (“AUM”) subject to incentive fees and the incentive fees, as calculated under each of the above methods:

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Note 2 Significant Accounting Policies (Continued)

Revenue Recognition – Incentive Revenue (Continued)

Revenue Recognition – Mutual Fund Administration

DHCM has an administrative and transfer agency services agreement with the Funds, under which DHCM performs certain services for each fund. These services include mutual fund administration, transfer agency and other related functions. For performing these services, each fund compensates DHCM a fee, which is calculated using the following annual rates times the average daily net assets of each respective series and share class:

(a) – Class Y commenced operations on January 3, 2012.

The Funds have selected and contractually engaged certain vendors to fulfill various services to benefit the Funds’ shareholders or to satisfy regulatory requirements of the Funds. These services include, among others, required fund shareholder mailings, federal and state registrations, and legal and audit services. DHCM, in fulfilling a portion of its role under the administration agreement with the Funds, acts as agent to pay these obligations of the Funds. Each vendor is independently responsible for fulfillment of the services it has been engaged to provide and negotiates fees and terms with the management and board of trustees of the Funds. The fee that the Funds pay to DHCM is reviewed annually by the Funds’ board of trustees and specifically takes into account the contractual expenses that DHCM pays on behalf of the Funds. As a result, DHCM is not involved in the delivery or pricing of these services and bears no risk related to these

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Note 2 Significant Accounting Policies (Continued)

Revenue Recognition – Mutual Fund Administration (Continued)

services. Revenue has been recorded net of these Fund related expenses, in accordance with the appropriate accounting treatment for this agency relationship. In addition, DHCM finances the upfront commissions which are paid by the Fund’s principal underwriter to brokers who sell Class C shares of the Funds. As financer, DHCM advances to the underwriter the commission amount to be paid to the selling broker at the time of sale. These advances are capitalized and amortized over 12 months to correspond with the repayments DHCM receives from the principal underwriter to recoup this commission advancement.

Beacon Hill has underwriting and administrative service agreements with certain clients, including registered mutual funds. The fee arrangements vary from client to client based upon services provided and are recorded as revenue under Mutual Fund Administration on the Consolidated Statements of Income. Part of Beacon Hill’s role as underwriter is to act as an agent on behalf of its mutual fund clients to receive 12b-1/service fees and commission revenue and facilitate the payment of those fees and commissions to third parties who provide services to the funds and their shareholders. The amount of 12b-1/service fees and commissions are determined by each mutual fund client and Beacon Hill bears no financial risk related to these services. As a result, 12b-1/service fees and commission revenue has been recorded net of the expense payments to third parties, in accordance with the appropriate accounting treatment for this agency relationship.

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Revenue Recognition – Mutual Fund Administration (Continued)

Mutual fund administration gross and net revenue are summarized below:

Third Party Distribution Expense

Third party distribution expenses are earned by various third party financial services firms based on sales and/or assets of the Company’s investment products generated by the respective firms. Expenses recognized represent actual payments made to the third party firms and are recorded in the period earned based on the terms of the various contracts.

Income Taxes

The Company accounts for income taxes through an asset and liability approach. A net deferred tax asset or liability is determined based on the tax effects of the various temporary differences between the book and tax bases of the various balance sheet assets and liabilities and gives current recognition to changes in tax rates and laws.

The Company has analyzed its tax positions taken on federal income tax returns for all open tax years (tax years ended December 31, 2008 through 2011) to determine any uncertainty in income taxes and has recognized no adjustment in the net asset or liability.

Earnings Per Share

Earnings per share (“EPS”) is computed by dividing net income by the weighted average number of common shares outstanding for the period. Diluted EPS reflects the potential dilution of EPS that could occur if outstanding warrants were exercised. For the periods presented, the Company does not have dilutive securities outstanding.

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As of June 30, 2012, the Company held investments worth $15.4 million and an estimated cost basis of $11.7 million. The following table summarizes the market value of these investments as of June 30, 2012 and December 31, 2011:

(a) – Effective January 3, 2012, Diamond Hill Research Partners, L.P. converted to Diamond Hill Research Opportunities Fund, a series of the Diamond Hill Funds.

DHCM is the managing member of the Diamond Hill General Partner LLC, which is the General Partner of the Partnerships. The underlying assets of the Partnerships are cash and marketable equity securities. Summary financial information, including the Company’s carrying value and income from the Partnerships is as follows:

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Common Shares

The Company has only one class of securities, Common Shares.

Authorization of Preferred Shares

The Company’s Articles of Incorporation authorize the issuance of 1,000,000 shares of “blank check” preferred shares with such designations, rights and preferences, as may be determined from time to time by the Company’s Board of Directors. The Board of Directors is authorized, without shareholder approval, to issue preferred stock with dividend, liquidation, conversion, voting, or other rights, which could adversely affect the voting or other rights of the holders of the Common Shares. There were no shares of preferred stock issued or outstanding at June 30, 2012 or December 31, 2011.

Equity Incentive Plans

2011 Equity and Cash Incentive Plan

At the Company’s annual shareholder meeting on April 26, 2011, shareholders approved the 2011 Equity and Cash Incentive Plan (“2011 Plan”). The 2011 Plan is intended to facilitate the Company’s ability to attract and retain staff, provide additional incentive to employees, directors and consultants, and promote the success of the Company’s business. The 2011 Plan authorizes the issuance of 600,000 Common Shares of the Company in various forms of equity awards. As of June 30, 2012, there were 338,076 Common Shares available for issuance under the 2011 Plan. The 2011 Plan provides that the Board of Directors, or a committee appointed by the Board, may grant awards and otherwise administer the 2011 Plan. Restricted stock grants issued under the 2011 Plan, which vest over time, are recorded as deferred compensation in the equity section of the balance sheet on the grant date and then recognized as compensation expense based on the grant date price over the vesting period of the respective grant.

2005 Employee and Director Equity Incentive Plan

At the Company’s annual shareholder meeting on May 12, 2005, shareholders approved the 2005 Employee and Director Equity Incentive Plan (“2005 Plan”). With the approval of the 2011 Plan, there are no longer any Common Shares available for future issuance under the 2005 Plan. Outstanding grants under the 2005 Plan are unaffected and remain issued and outstanding. Restricted stock grants issued under the 2005 Plan, which vest over time, are recorded as deferred compensation in the equity section of the balance sheet on the grant date and then recognized as compensation expense based on the grant date price over the vesting period of the respective grant.

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Equity Incentive Plans (Continued)

Restricted Stock Grant Transactions

The following table represents a roll-forward of outstanding restricted stock grants issued pursuant to the 2011 and 2005 Plans and related activity during the year ended December 31, 2011 and the six months ended June 30, 2012:

Total deferred compensation related to unvested restricted stock grants was $15,738,826 as of June 30, 2012. Expense recognition of deferred compensation over the remaining vesting periods is as follows:

401(k) Plan

The Company sponsors a 401(k) plan under which all employees participate. Employees may contribute a portion of their compensation subject to certain limits based on federal tax laws. The Company makes matching contributions of Common Shares of the Company with a value equal to 200 percent of the first six percent of an employee’s compensation contributed to the plan. Employees become fully vested in the matching contributions after six plan years of employment. The following table summarizes the Company’s expenses attributable to the plan during the three and six months ended June 30, 2012 and 2011:

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The Company leases approximately 25,500 square feet of office space at two locations. The following table summarizes the total lease and operating expenses for the three and six months ended June 30, 2012 and 2011:

The approximate future minimum lease payments under the operating leases are as follows:

In addition to the above rent, the Company will also be responsible for normal operating expenses of the properties. Such operating expenses were approximately $9.60 per square foot in 2011, on a combined basis, and are expected to be approximately $9.69 per square foot in 2012.

The provision for income taxes for the three and six months ended June 30, 2012 and 2011 consists of federal, state and city income taxes. During 2011, the Company and its subsidiaries fully utilized the capital loss carry forward outstanding from December 31, 2010. As of June 30, 2012, there was no capital loss carry forward outstanding.

The following table sets forth the computation for earnings per share (“EPS”):

For the periods presented, the Company does not have dilutive securities outstanding.

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BHIL, a wholly owned subsidiary of the Company and principal underwriter for mutual funds, is subject to the U.S. Securities and Exchange Commission (“SEC”) uniform net capital rule, which requires the maintenance of minimum net capital. BHIL’s net capital exceeded its minimum net capital requirement at June 30, 2012 and December 31, 2011. The net capital balances, minimum net capital requirements, and ratio of aggregate indebtedness to net capital for BHIL are summarized below as of June 30, 2012 and December 31, 2011:

The Company indemnifies its directors and certain of its officers and employees for certain liabilities that might arise from their performance of their duties to the Company. Additionally, in the normal course of business, the Company enters into agreements that contain a variety of representations and warranties and which provide general indemnifications. Certain agreements do not contain any limits on the Company’s liability and would involve future claims that may be made against the Company that have not yet occurred. Therefore, it is not possible to estimate the Company’s potential liability under these indemnities. Further, the Company maintains insurance policies that may provide coverage against certain claims under these indemnities.

On July 18, 2012, the Company liquidated Diamond Hill Offshore Ltd., and Diamond Hill Investment Partners II, LP, both private investment funds. Substantially all of the assets in these funds were redeemed and paid out to investors during June 2012 and therefore, the effect of the liquidation is already reflected in June 30, 2012 asset under management. In addition, the Company has started the process of dissolving its subsidiary Diamond Hill GP (Cayman) Ltd., which acted as the general partner to the master fund of the above two funds. The dissolution is expected to be substantially completed during the third quarter of 2012.

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DIAMOND HILL INVESTMENT GROUP, INC.

Forward-looking Statements

Throughout this quarterly report on Form 10-Q, the Company may make forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, relating to such matters as anticipated operating results, prospects for achieving the critical threshold of assets under management, technological developments, economic trends (including interest rates and market volatility), expected transactions and acquisitions and similar matters. The words “believe,” “expect,” “anticipate,” “estimate,” “should,” “hope,” “seek,” “plan,” “intend” and similar expressions identify forward-looking statements that speak only as of the date thereof. While the Company believes that the assumptions underlying its forward-looking statements are reasonable, investors are cautioned that any of the assumptions could prove to be inaccurate and accordingly, the actual results and experiences of the Company could differ materially from the anticipated results or other expectations expressed by the Company in its forward-looking statements. Factors that could cause such actual results or experiences to differ from results discussed in the forward-looking statements include, but are not limited to: the adverse effect from a decline in the securities markets; a decline in the performance of the Company’s products; changes in interest rates; a general or prolonged downturn in the economy; changes in government policy and regulation, including monetary policy; changes in the Company’s ability to attract or retain key employees; unforeseen costs and other effects related to legal proceedings or investigations of governmental and self-regulatory organizations; and other risks identified from time-to-time in the Company’s public documents on file with the SEC.

General

The Company, an Ohio corporation organized in 1990, derives its consolidated revenue and net income from investment advisory and fund administration services provided by its subsidiaries Diamond Hill Capital Management, Inc. (“DHCM”), Beacon Hill Fund Services, Inc. (“BHFS”), and BHIL Distributors, Inc. (“BHIL”). BHFS and BHIL collectively operate as Beacon Hill. DHCM is a registered investment adviser under the Investment Advisers Act of 1940 providing investment advisory services to individuals and institutional investors through Diamond Hill Funds, separate accounts, and private investment funds (generally known as “hedge funds”). Beacon Hill was incorporated during the first quarter of 2008, and provides certain fund administration services and underwriting services to mutual fund companies, including Diamond Hill Funds.

In this section, the Company discusses and analyzes the consolidated results of operations for the three and six month periods ending June 30, 2012 and 2011 and other factors that may affect future financial performance. The accompanying unaudited consolidated financial statements were prepared in accordance with the instructions for Form 10-Q and, therefore, do not include information or footnotes necessary for a complete presentation of financial position, results of operations and cash flows in conformity with United States generally accepted accounting principles. Accordingly, these financial statements should be read in conjunction with the Consolidated Financial Statements and Notes thereto of the Company included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2011. However, in the opinion of management, all adjustments (consisting of only normal recurring accruals) which are necessary for a fair presentation of the financial statements have been included. The results of operations for the three and six month periods ended June 30, 2012 are not necessarily indicative of the results which may be expected for the entire fiscal year.

The Company’s revenue is derived primarily from investment advisory and fund administration fees. Investment advisory and fund administration fees paid to the Company are generally based on the value of the investment portfolios managed by the Company and fluctuate with changes in the total value of the assets under management (“AUM”). Such fees are recognized in the period that the Company manages these assets. The Company can also earn variable incentive fees which are based on investment results in client accounts and are achieved if those results exceed a specified hurdle. The Company’s primary expense is employee compensation and benefits.

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Assets Under Management

As of June 30, 2012, AUM totaled $9.2 billion, unchanged compared to June 30, 2011. Revenues are highly dependent on both the value and composition of AUM. The following tables show AUM by product and investment objective for the dates indicated and a roll-forward of the change in AUM for the three and six months ended June 30, 2012 and 2011:

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Consolidated Results of Operations

The following is a discussion of the consolidated results of operations of the Company.