MAIN 10-K Fiscal year ended Dec. 31, 2018

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TABLE OF CONTENTS
Item 8. Consolidated Financial Statements and Supplementary Data
PART IV

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UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

Form 10-K

Commission File Number: 001-33723

Main Street Capital Corporation
(Exact name of registrant as specified in its charter)

(713) 350-6000
(Registrant's telephone number, including area code)

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act:

None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.    Yes o No þ

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.    Yes o No þ

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 (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    Yes þ No o

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted 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 such files).    Yes o No o

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of registrant's knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K. þ

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

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. o

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

The aggregate market value of the registrant's common stock held by non-affiliates of the registrant as of June 30, 2018, was approximately $2,178.0 million based upon the last sale price for the registrant's common stock on that date.

The number of outstanding common shares of the registrant as of February 28, 2019 was 61,847,438.

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the registrants' definitive Proxy Statement for its 2019 Annual Meeting of Stockholders, to be filed with the Securities and Exchange Commission, are incorporated by reference in this Annual Report on Form 10-K in response to Part III.

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CAUTIONARY STATEMENT CONCERNING FORWARD-LOOKING STATEMENTS

This Annual Report on Form 10-K contains forward-looking statements regarding the plans and objectives of management for future operations. Any such forward-looking statements may involve known and unknown risks, uncertainties and other factors which may cause our actual results, performance or achievements to be materially different from future results, performance or achievements expressed or implied by any forward-looking statements. Forward-looking statements, which involve assumptions and describe our future plans, strategies and expectations, are generally identifiable by use of the words "may," "will," "should," "expect," "anticipate," "estimate," "believe," "intend" or "project" or the negative of these words or other variations on these words or comparable terminology. These forward-looking statements are based on assumptions that may be incorrect, and we cannot assure you that the projections included in these forward-looking statements will come to pass. Our actual results could differ materially from those expressed or implied by the forward-looking statements as a result of various factors, including the factors discussed in Item 1A entitled "Risk Factors" in Part I of this Annual Report on Form 10-K and elsewhere in this Annual Report on Form 10-K. Other factors that could cause actual results to differ materially include changes in the economy and future changes in laws or regulations and conditions in our operating areas.

We have based the forward-looking statements included in this Annual Report on Form 10-K on information available to us on the date of this Annual Report on Form 10-K, and we assume no obligation to update any such forward-looking statements, unless we are required to do so by applicable law. However, you are advised to refer to any additional disclosures that we may make directly to you or through reports that we in the future may file with the Securities and Exchange Commission ("SEC"), including subsequent annual reports on Form 10-K, quarterly reports on Form 10-Q and current reports on Form 8-K.

PART I

Item 1. Business

ORGANIZATION

Main Street Capital Corporation ("MSCC") is a principal investment firm primarily focused on providing customized debt and equity financing to lower middle market ("LMM") companies and debt capital to middle market ("Middle Market") companies. The portfolio investments of MSCC and its consolidated subsidiaries are typically made to support management buyouts, recapitalizations, growth financings, refinancings and acquisitions of companies that operate in a variety of industry sectors. MSCC seeks to partner with entrepreneurs, business owners and management teams and generally provides "one stop" financing alternatives within its LMM portfolio. MSCC and its consolidated subsidiaries invest primarily in secured debt investments, equity investments, warrants and other securities of LMM companies based in the United States and in secured debt investments of Middle Market companies generally headquartered in the United States.

MSCC was formed in March 2007 to operate as an internally managed business development company ("BDC") under the Investment Company Act of 1940, as amended (the "1940 Act"). MSCC wholly owns several investment funds, including Main Street Mezzanine Fund, LP ("MSMF"), Main Street Capital II, LP ("MSC II") and Main Street Capital III, LP ("MSC III" and, collectively with MSMF and MSC II, the "Funds"), and each of their general partners. The Funds are each licensed as a Small Business Investment Company ("SBIC") by the United States Small Business Administration ("SBA"). Because MSCC is internally managed, all of the executive officers and other employees are employed by MSCC. Therefore, MSCC does not pay any external investment advisory fees, but instead directly incurs the operating costs associated with employing investment and portfolio management professionals.

MSC Adviser I, LLC (the "External Investment Manager") was formed in November 2013 as a wholly owned subsidiary of MSCC to provide investment management and other services to parties other than MSCC and its subsidiaries or their portfolio companies ("External Parties") and receives fee income for such services. MSCC has been granted no-action relief by the SEC to allow the External Investment Manager to

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register as a registered investment adviser under the Investment Advisers Act of 1940, as amended (the "Advisers Act"). Since the External Investment Manager conducts all of its investment management activities for External Parties, it is accounted for as a portfolio investment of MSCC and is not included as a consolidated subsidiary of MSCC in MSCC's consolidated financial statements.

MSCC has elected to be treated for U.S. federal income tax purposes as a regulated investment company ("RIC") under Subchapter M of the Internal Revenue Code of 1986, as amended (the "Code"). As a result, MSCC generally will not pay corporate-level U.S. federal income taxes on any net ordinary taxable income or capital gains that it distributes to its stockholders.

MSCC has certain direct and indirect wholly owned subsidiaries that have elected to be taxable entities (the "Taxable Subsidiaries"). The primary purpose of the Taxable Subsidiaries is to permit MSCC to hold equity investments in portfolio companies which are "pass-through" entities for tax purposes.

Unless otherwise noted or the context otherwise indicates, the terms "we," "us," "our," the "Company" and "Main Street" refer to MSCC and its consolidated subsidiaries, which include the Funds and the Taxable Subsidiaries.

The following diagram depicts our organizational structure:

*

Other Holding Companies includes the Taxable Subsidiaries and other entities formed for operational purposes. Each of these companies is directly or indirectly wholly owned by MSCC.

**

The External Investment Manager is accounted for as a portfolio investment at fair value, as opposed to a consolidated subsidiary, and is indirectly wholly owned by MSCC.

CORPORATE INFORMATION

Our principal executive offices are located at 1300 Post Oak Boulevard, 8 ^th Floor, Houston, Texas 77056. We maintain a Web site on the Internet at www.mainstcapital.com . We make available free of charge on our Web site our annual reports on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K, and all amendments to those reports as soon as reasonably practicable after such material is electronically filed with or furnished to the SEC. Information contained on our Web site is not incorporated by reference into this Annual Report on Form 10-K, and you should not consider that information to be part of this Annual Report on Form 10-K. Our annual reports on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K, and all amendments to those reports and other public filings are also available free of charge on the EDGAR Database on the SEC's Web site at www.sec.gov .

OVERVIEW OF OUR BUSINESS

Our principal investment objective is to maximize our portfolio's total return by generating current income from our debt investments and capital appreciation from our equity and equity-related investments,

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including warrants, convertible securities and other rights to acquire equity securities in a portfolio company. Our LMM companies generally have annual revenues between $10 million and $150 million, and our LMM portfolio investments generally range in size from $5 million to $50 million. Our Middle Market investments are made in businesses that are generally larger in size than our LMM portfolio companies, with annual revenues typically between $150 million and $1.5 billion, and our Middle Market investments generally range in size from $3 million to $20 million. Our private loan ("Private Loan") portfolio investments are primarily debt securities in privately held companies which have been originated through strategic relationships with other investment funds on a collaborative basis. Private Loan investments are typically similar in size, structure, terms and conditions to investments we hold in our LMM portfolio and Middle Market portfolio.

We seek to fill the financing gap for LMM businesses, which, historically, have had limited access to financing from commercial banks and other traditional sources. The underserved nature of the LMM creates the opportunity for us to meet the financing needs of LMM companies while also negotiating favorable transaction terms and equity participations. Our ability to invest across a company's capital structure, from secured loans to equity securities, allows us to offer portfolio companies a comprehensive suite of financing options, or a "one stop" financing solution. Providing customized, "one stop" financing solutions is important to LMM portfolio companies. We generally seek to partner directly with entrepreneurs, management teams and business owners in making our investments. Our LMM portfolio debt investments are generally secured by a first lien on the assets of the portfolio company and typically have a term of between five and seven years from the original investment date.

Our Middle Market portfolio investments primarily consist of direct investments in or secondary purchases of interest-bearing debt securities in privately held companies that are generally larger in size than the companies included in our LMM portfolio. Our Middle Market portfolio debt investments are generally secured by either a first or second priority lien on the assets of the portfolio company and typically have an expected duration of between three and seven years from the original investment date.

Our Private Loan portfolio investments are primarily debt securities in privately held companies which have been originated through strategic relationships with other investment funds on a collaborative basis, and are often referred to in the debt markets as "club deals." Private Loan investments are typically similar in size, structure, terms and conditions to investments we hold in our LMM portfolio and Middle Market portfolio. Our Private Loan portfolio debt investments are generally secured by either a first or second priority lien on the assets of the portfolio company and typically have a term of between three and seven years from the original investment date.

Our other portfolio ("Other Portfolio") investments primarily consist of investments which are not consistent with the typical profiles for our LMM, Middle Market or Private Loan portfolio investments, including investments which may be managed by third parties. In our Other Portfolio, we may incur indirect fees and expenses in connection with investments managed by third parties, such as investments in other investment companies or private funds.

Our external asset management business is conducted through the External Investment Manager. The External Investment Manager earns management fees based on the assets of the funds under management and may earn incentive fees, or a carried interest, based on the performance of the funds managed. We have entered into an agreement with the External Investment Manager to share employees in connection with its asset management business generally, and specifically for its relationship with HMS Income Fund, Inc. ("HMS Income"). Through this agreement, we share employees with the External Investment Manager, including their related infrastructure, business relationships, management expertise and capital raising capabilities.

Our portfolio investments are generally made through MSCC and the Funds. MSCC and the Funds share the same investment strategies and criteria, although they are subject to different regulatory regimes (see "Regulation"). An investor's return in MSCC will depend, in part, on the Funds' investment returns as they are wholly owned subsidiaries of MSCC.

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The level of new portfolio investment activity will fluctuate from period to period based upon our view of the current economic fundamentals, our ability to identify new investment opportunities that meet our investment criteria, and our ability to consummate the identified opportunities. The level of new investment activity, and associated interest and fee income, will directly impact future investment income. In addition, the level of dividends paid by portfolio companies and the portion of our portfolio debt investments on non-accrual status will directly impact future investment income. While we intend to grow our portfolio and our investment income over the long term, our growth and our operating results may be more limited during depressed economic periods. However, we intend to appropriately manage our cost structure and liquidity position based on applicable economic conditions and our investment outlook. The level of realized gains or losses and unrealized appreciation or depreciation on our investments will also fluctuate depending upon portfolio activity, economic conditions and the performance of our individual portfolio companies. The changes in realized gains and losses and unrealized appreciation or depreciation could have a material impact on our operating results.

Because we are internally managed, we do not pay any external investment advisory fees, but instead directly incur the operating costs associated with employing investment and portfolio management professionals. We believe that our internally managed structure provides us with a beneficial operating expense structure when compared to other publicly traded and privately held investment firms which are externally managed, and our internally managed structure allows us the opportunity to leverage our non-interest operating expenses as we grow our Investment Portfolio.

During May 2012, we entered into an investment sub-advisory agreement with HMS Adviser, LP ("HMS Adviser"), which is the investment advisor to HMS Income, a non-listed BDC, to provide certain investment advisory services to HMS Adviser. In December 2013, after obtaining required no-action relief from the SEC to allow us to own a registered investment adviser, we assigned the sub-advisory agreement to the External Investment Manager since the fees received from such arrangement could otherwise have negative consequences on our ability to meet the source-of-income requirement necessary for us to maintain our RIC tax treatment. Under the investment sub-advisory agreement, the External Investment Manager is entitled to 50% of the base management fee and the incentive fees earned by HMS Adviser under its advisory agreement with HMS Income.

During April 2014, we received an exemptive order from the SEC permitting co-investments by us and HMS Income in certain negotiated transactions where co-investing would otherwise be prohibited under the 1940 Act. We have made, and in the future intend to continue to make, such co-investments with HMS Income in accordance with the conditions of the order. The order requires, among other things, that we and the External Investment Manager consider whether each such investment opportunity is appropriate for HMS Income and, if it is appropriate, to propose an allocation of the investment opportunity between us and HMS Income. Because the External Investment Manager may receive performance-based fee compensation from HMS Income, this may provide it an incentive to allocate opportunities to HMS Income instead of us. However, both we and the External Investment Manager have policies and procedures in place to manage this conflict.

RECENT DEVELOPMENTS

In January 2019, we led a new portfolio investment to facilitate the minority recapitalization of Centre Technologies, Inc. ("Centre"), a premier provider of IT hardware, software and service solutions. We, along with our co-investors, partnered with Centre's founder and Chief Executive Officer and management team to facilitate the transaction, with us funding $18.1 million in a combination of first-lien, senior secured term debt and a direct equity investment. Headquartered in Houston, Texas, and founded in 2006, Centre has established itself as a mission critical IT solutions provider offering a full suite of solutions including managed and hosted services, value-added sourcing and integration, and project services.

In January 2019, we led a new portfolio investment to facilitate the management buyout of CompareNetworks Inc. ("CompareNetworks"), a leading provider of media, marketing and technology

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solutions that drive revenue for life science and healthcare product manufacturers. We, along with our co-investors, partnered with CompareNetworks' founders and management team to facilitate the transaction, with us funding $10.7 million in a combination of first-lien, senior secured term debt and a direct equity investment. Headquartered in South San Francisco, California, and founded in 2000, CompareNetworks provides life scientists, researchers, lab-based professionals, pharmaceutical professionals and healthcare professionals with digital tools and information resources to research, identify and determine which products and technologies to use.

In January 2019, we fully exited our equity investment in Boss Industries, LLC ("Boss"). Boss markets, designs and manufacturers vehicle-mounted, and portable air compressor and generator systems utilized in municipal and utility services, energy product and industrial services. We realized a gain of approximately $4.0 million on the exit of our equity investment in Boss.

During February 2019, we declared regular monthly dividends of $0.200 per share for each month of April, May and June 2019. These regular monthly dividends equal a total of $0.600 per share for the second quarter of 2019 and represent a 5.3% increase from the dividends declared for the second quarter of 2018. Including the dividends declared for the second quarter of 2019, we will have paid $25.420 per share in cumulative dividends since our October 2007 initial public offering.

BUSINESS STRATEGIES

Our principal investment objective is to maximize our portfolio's total return by generating current income from our debt investments and capital appreciation from our equity and equity-related investments, including warrants, convertible securities and other rights to acquire equity securities in a portfolio company. We have adopted the following business strategies to achieve our investment objective:

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Deliver Customized Financing Solutions in the Lower Middle Market. We offer LMM portfolio companies customized debt and equity financing solutions that are tailored to the facts and circumstances of each situation. We believe our ability to provide a broad range of customized financing solutions to LMM companies sets us apart from other capital providers that focus on providing a limited number of financing solutions. Our ability to invest across a company's capital structure, from senior secured loans to subordinated debt to equity securities, allows us to offer LMM portfolio companies a comprehensive suite of financing options, or a "one stop" financing solution.



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Focus on Established Companies. We generally invest in companies with established market positions, experienced management teams and proven revenue streams. We believe that those companies generally possess better risk-adjusted return profiles than newer companies that are building their management teams or are in the early stages of building a revenue base. We also believe that established companies in our targeted size range also generally provide opportunities for capital appreciation.



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Leverage the Skills and Experience of Our Investment Team. Our investment team has significant experience in lending to and investing in LMM and Middle Market companies. The members of our investment team have broad investment backgrounds, with prior experience at private investment funds, investment banks and other financial services companies and currently include seven certified public accountants and three Chartered Financial Analyst® charter holders. The expertise of our investment team in analyzing, valuing, structuring, negotiating and closing transactions should provide us with competitive advantages by allowing us to consider customized financing solutions and non-traditional or complex structures for our portfolio companies. Also, the reputation of our investment team has and should continue to enable us to generate additional revenue in the form of management and incentive fees in connection with us providing advisory services to other investment funds.



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Invest Across Multiple Companies, Industries, Regions and End Markets. We seek to maintain a portfolio of investments that is appropriately balanced among various companies, industries, geographic regions and end markets. This portfolio balance is intended to mitigate the potential effects of negative economic events for particular companies, regions, industries and end markets.

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Capitalize on Strong Transaction Sourcing Network. Our investment team seeks to leverage its extensive network of referral sources for portfolio company investments. We have developed a reputation in our marketplace as a responsive, efficient and reliable source of financing, which has created a growing stream of proprietary deal flow for us.



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Benefit from Lower, Fixed, Long-Term Cost of Capital. The SBIC licenses held by the Funds have allowed them to issue SBA-guaranteed debentures. SBA-guaranteed debentures carry long-term fixed interest rates that are generally lower than interest rates on comparable bank loans and other debt. Because lower-cost SBA leverage is, and will continue to be, a significant part of our capital base through the Funds, our relative cost of debt capital should be lower than many of our competitors. In addition, the SBIC leverage that we receive through the Funds represents a stable, long-term component of our capital structure with proper matching of duration and cost compared to our LMM portfolio investments. We also maintain an investment grade rating from Standard & Poor's Ratings Services which provides us the opportunity and flexibility to obtain additional, attractive long-term financing options to supplement our capital structure, including the unsecured notes with fixed interest rates we issued in 2014 and 2017.

INVESTMENT CRITERIA

Our investment team has identified the following investment criteria that it believes are important in evaluating prospective portfolio companies. Our investment team uses these criteria in evaluating investment opportunities. However, not all of these criteria have been, or will be, met in connection with each of our investments:

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Proven Management Team with Meaningful Equity Stake. We look for operationally-oriented management with direct industry experience and a successful track record. In addition, we expect the management team of each LMM portfolio company to have meaningful equity ownership in the portfolio company to better align our respective economic interests. We believe management teams with these attributes are more likely to manage the companies in a manner that both protects our debt investment and enhances the value of our equity investment.



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Established Companies with Positive Cash Flow. We seek to invest in established companies with sound historical financial performance. We typically focus on LMM companies that have historically generated EBITDA of $3 million to $20 million and commensurate levels of free cash flow. We also pursue investments in debt securities of Middle Market companies that are generally established companies with sound historical financial performance that are generally larger in size than LMM companies. We generally do not invest in start-up companies or companies with speculative business plans.



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Defensible Competitive Advantages/Favorable Industry Position. We primarily focus on companies having competitive advantages in their respective markets and/or operating in industries with barriers to entry, which may help to protect their market position and profitability.



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Exit Alternatives. We exit our debt investments primarily through the repayment of our investment from internally generated cash flow of the portfolio company and/or a refinancing. In addition, we seek to invest in companies whose business models and expected future cash flows may provide alternate methods of repaying our investment, such as through a strategic acquisition by other industry participants or a recapitalization.

INVESTMENT PORTFOLIO

The Investment Portfolio, as used herein, refers to all of our investments in LMM portfolio companies, investments in Middle Market portfolio companies, Private Loan portfolio investments, Other Portfolio investments, and the investment in the External Investment Manager. Our LMM portfolio investments primarily consist of secured debt, equity warrants and direct equity investments in privately held, LMM

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companies based in the United States. Our Middle Market portfolio investments primarily consist of direct investments in or secondary purchases of interest-bearing debt securities in privately held companies based in the United States that are generally larger in size than the companies included in our LMM portfolio. Our Private Loan portfolio investments primarily consist of investments in interest-bearing debt securities in companies that are consistent with the size of companies in our LMM portfolio or our Middle Market portfolio, but are investments that we originate on a collaborative basis with other investment funds, and are often referred to in the debt markets as "club deals." Our Other Portfolio investments primarily consist of investments which are not consistent with the typical profiles for our LMM, Middle Market and Private Loan portfolio investments, including investments which may be managed by third parties. In our Other Portfolio, we may incur indirect fees and expenses in connection with investments managed by third parties, such as investments in other investment companies or private funds.

Debt Investments

Historically, we have made LMM debt investments principally in the form of single tranche debt. Single tranche debt financing involves issuing one debt security that blends the risk and return profiles of both first lien secured and subordinated debt. We believe that single tranche debt is more appropriate for many LMM companies given their size in order to reduce structural complexity and potential conflicts among creditors.

Our LMM debt investments generally have a term of five to seven years from the original investment date, with limited required amortization prior to maturity, and provide for monthly or quarterly payment of interest at interest rates generally between 10% and 14% per annum, payable currently in cash. Interest rate terms can include either fixed or floating rate terms. In addition, certain LMM debt investments may have a form of interest that is not paid currently but is accrued and added to the loan balance and paid at maturity. We refer to this form of interest as payment-in-kind, or PIK, interest. We typically structure our LMM debt investments with the maximum seniority and collateral that we can reasonably obtain while seeking to achieve our total return target. In most cases, our LMM debt investment will be collateralized by a first priority lien on substantially all the assets of the portfolio company. In addition to seeking a senior lien position in the capital structure of our LMM portfolio companies, we seek to limit the downside potential of our LMM debt investments by negotiating covenants that are designed to protect our LMM debt investments while affording our portfolio companies as much flexibility in managing their businesses as is reasonable. Such restrictions may include affirmative and negative covenants, default penalties, lien protection, change of control or change of management provisions, key-man life insurance, guarantees, equity pledges, personal guaranties, where appropriate, and put rights. In addition, we typically seek board representation or observation rights in all of our LMM portfolio companies. Interest rate terms can include either fixed or floating rate terms.

While we will continue to focus our LMM debt investments primarily on single tranche debt investments, we also anticipate structuring some of our debt investments as mezzanine loans. We anticipate that these mezzanine loans will be primarily junior secured or unsecured, subordinated loans that provide for relatively high interest rates payable currently in cash that will provide us with significant interest income plus the additional opportunity for income and gains through PIK interest and equity warrants and other similar equity instruments issued in conjunction with these mezzanine loans. These loans typically will have interest-only payments in the early years, with amortization of principal deferred to the later years of the mezzanine loan term. Typically, our mezzanine loans will have maturities of three to five years. We will generally target interest rates of 12% to 14%, payable currently in cash for our mezzanine loan investments with higher targeted total returns from equity warrants or PIK interest.

We also pursue debt investments in Middle Market companies. Our Middle Market portfolio investments primarily consist of direct investments or secondary purchases of interest-bearing debt securities in privately held companies based in the United States that are generally larger in size than the companies included in our LMM portfolio. Our Middle Market portfolio debt investments are generally secured by either a first or second priority lien on the assets of the portfolio company and typically have a term of between three and seven years from the original investment date. The debt investments in our Middle Market portfolio have rights and protections that are similar to those in our LMM debt investments, which may include affirmative

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and negative covenants, default penalties, lien protection, change of control provisions, guarantees and equity pledges. The Middle Market debt investments generally have floating interest rates at the London Interbank Offered Rate ("LIBOR") plus a margin, and are typically subject to LIBOR floors.

Our Private Loan portfolio investments primarily consist of investments in interest-bearing debt securities in companies that are consistent with the size of companies in our LMM portfolio or our Middle Market portfolio, but are investments which have been originated through strategic relationships with other investment funds on a collaborative basis. Our Private Loan portfolio debt investments are generally secured by either a first or second priority lien and typically have a term of between three and seven years from the original investment date.

Warrants

In connection with our debt investments, we occasionally receive equity warrants to establish or increase our equity interest in the portfolio company. Warrants we receive in connection with a debt investment typically require only a nominal cost to exercise, and thus, as a portfolio company appreciates in value, we may achieve additional investment return from this equity interest. We typically structure the warrants to provide provisions protecting our rights as a minority-interest holder, as well as secured or unsecured put rights, or rights to sell such securities back to the portfolio company, upon the occurrence of specified events. In certain cases, we also may obtain registration rights in connection with these equity interests, which may include demand and "piggyback" registration rights.

Direct Equity Investments

We also will seek to make direct equity investments in situations where it is appropriate to align our interests with key management and stockholders of our LMM portfolio companies, and to allow for participation in the appreciation in the equity values of our LMM portfolio companies. We usually make our direct equity investments in connection with debt investments in our LMM portfolio companies. In addition, we may have both equity warrants and direct equity positions in some of our LMM portfolio companies. We seek to maintain fully diluted equity positions in our LMM portfolio companies of 5% to 50%, and may have controlling equity interests in some instances. We have a value orientation toward our direct equity investments and have traditionally been able to purchase our equity investments at reasonable valuations.

INVESTMENT PROCESS

Our management team's investment committee is responsible for all aspects of our LMM investment process. The current members of our investment committee are Dwayne L. Hyzak, our Chief Executive Officer and Senior Managing Director, David Magdol, our President, Chief Investment Officer and Senior Managing Director, Vincent D. Foster, our Executive Chairman, and Curtis L. Hartman, our Vice-Chairman, Chief Credit Officer and Senior Managing Director.

Our management team's credit committee is responsible for all aspects of our Middle Market portfolio investment process. The current members of our credit committee are Messrs. Hyzak, Foster, Hartman and Nicholas T. Meserve, Managing Director of our Middle Market investment team.

Investment process responsibility for each Private Loan portfolio investment is delegated to either the investment committee or the credit committee based upon the nature of the investment and the manner in which it was originated. Similarly, the investment processes for each Private Loan portfolio investment, from origination to close and to eventual exit, will follow the processes for our LMM portfolio investments or our Middle Market portfolio investments as outlined below, or a combination thereof.

Our investment strategy involves a "team" approach, whereby potential transactions are screened by several members of our investment team before being presented to the investment committee or the credit

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committee, as applicable. Our investment committee and credit committee each meet on an as needed basis depending on transaction volume. We generally categorize our investment process into seven distinct stages:

Deal Generation/Origination

Deal generation and origination is maximized through long-standing and extensive relationships with industry contacts, brokers, commercial and investment bankers, entrepreneurs, service providers such as lawyers, financial advisors and accountants, and current and former portfolio companies and investors. Our investment team has focused its deal generation and origination efforts on LMM and Middle Market companies, and we have developed a reputation as a knowledgeable, reliable and active source of capital and assistance in these markets.

Screening

During the screening process, if a transaction initially meets our investment criteria, we will perform preliminary due diligence, taking into consideration some or all of the following information:

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a comprehensive financial model based on quantitative analysis of historical financial performance, projections and pro forma adjustments to determine the estimated internal rate of return;



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a brief industry and market analysis;



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direct industry expertise imported from other portfolio companies or investors;



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preliminary qualitative analysis of the management team's competencies and backgrounds;



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potential investment structures and pricing terms; and



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regulatory compliance.

Upon successful screening of a proposed LMM transaction, the investment team makes a recommendation to our investment committee. If our investment committee concurs with moving forward on the proposed LMM transaction, we typically issue a non-binding term sheet to the company. For Middle Market portfolio investments, the initial term sheet is typically issued by the borrower, through the syndicating bank, and is screened by the investment team which makes a recommendation to our credit committee.

Term Sheet

For proposed LMM transactions, the non-binding term sheet will include the key economic terms based upon our analysis performed during the screening process as well as a proposed timeline and our qualitative expectation for the transaction. While the term sheet for LMM investments is non-binding, we typically receive an expense deposit in order to move the transaction to the due diligence phase. Upon execution of a term sheet, we begin our formal due diligence process.

For proposed Middle Market transactions, the initial term sheet will include key economic terms and other conditions proposed by the borrower and its representatives and the proposed timeline for the investment, which are reviewed by our investment team to determine if such terms and conditions are in agreement with our investment objectives.

Due Diligence

Due diligence on a proposed LMM investment is performed by a minimum of two of our investment professionals, whom we refer to collectively as the investment team, and certain external resources, who together conduct due diligence to understand the relationships among the prospective portfolio company's

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business plan, operations and financial performance. Our LMM due diligence review includes some or all of the following:

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site visits with management and key personnel;



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detailed review of historical and projected financial statements;



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operational reviews and analysis;



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interviews with customers and suppliers;



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detailed evaluation of company management, including background checks;



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review of material contracts;



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in-depth industry, market and strategy analysis;



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regulatory compliance analysis; and



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review by legal, environmental or other consultants, if applicable.

Due diligence on a proposed Middle Market investment is generally performed on materials and information obtained from certain external resources and assessed internally by a minimum of two of our investment professionals, who work to understand the relationships among the prospective portfolio company's business plan, operations and financial performance using the accumulated due diligence information. Our Middle Market due diligence review includes some or all of the following:

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detailed review of historical and projected financial statements;



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in-depth industry, market, operational and strategy analysis;



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regulatory compliance analysis; and



•

detailed review of the company's management team and their capabilities.

During the due diligence process, significant attention is given to sensitivity analyses and how the company might be expected to perform given downside, base-case and upside scenarios. In certain cases, we may decide not to make an investment based on the results of the diligence process.

Document and Close

Upon completion of a satisfactory due diligence review of a proposed LMM portfolio investment, the investment team presents the findings and a recommendation to our investment committee. The presentation contains information which can include, but is not limited to, the following:

•

company history and overview;



•

transaction overview, history and rationale, including an analysis of transaction strengths and risks;



•

analysis of key customers and suppliers and key contracts;



•

a working capital analysis;



•

an analysis of the company's business strategy;



•

a management and key equity investor background check and assessment;



•

third-party accounting, legal, environmental or other due diligence findings;



•

investment structure and expected returns;



•

anticipated sources of repayment and potential exit strategies;



•

pro forma capitalization and ownership;

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•

an analysis of historical financial results and key financial ratios;



•

sensitivities to management's financial projections;



•

regulatory compliance analysis findings; and



•

detailed reconciliations of historical to pro forma results.

Upon completion of a satisfactory due diligence review of a proposed Middle Market portfolio investment, the investment team presents the findings and a recommendation to our credit committee. The presentation contains information which can include, but is not limited to, the following:

•

company history and overview;



•

transaction overview, history and rationale, including an analysis of transaction strengths and risks;



•

analysis of key customers and suppliers;



•

an analysis of the company's business strategy;



•

investment structure and expected returns;



•

anticipated sources of repayment and potential exit strategies;



•

pro forma capitalization and ownership;



•

regulatory compliance analysis findings; and



•

an analysis of historical financial results and key financial ratios.

If any adjustments to the transaction terms or structures are proposed by the investment committee or credit committee, as applicable, such changes are made and applicable analyses are updated prior to approval of the transaction. Approval for the transaction must be made by the affirmative vote from a majority of the members of the investment committee or credit committee, as applicable, with the committee member managing the transaction, if any, abstaining from the vote. Upon receipt of transaction approval, the investment team will re-confirm regulatory compliance, process and finalize all required legal documents, and fund the investment.

Post-Investment

We continuously monitor the status and progress of the portfolio companies. We generally offer managerial assistance to our portfolio companies, giving them access to our investment experience, direct industry expertise and contacts. The same investment team that was involved in the investment process will continue its involvement in the portfolio company post-investment. This provides for continuity of knowledge and allows the investment team to maintain a strong business relationship with key management of our portfolio companies for post-investment assistance and monitoring purposes.

As part of the monitoring process of LMM portfolio investments, the investment team will analyze monthly and quarterly financial statements versus the previous periods and year, review financial projections, meet and discuss issues or opportunities with management, attend board meetings and review all compliance certificates and covenants. While we maintain limited involvement in the ordinary course operations of our LMM portfolio companies, we maintain a higher level of involvement in non-ordinary course financing or strategic activities and any non-performing scenarios. We also monitor the performance of our Middle Market portfolio investments; however, due to the larger size and higher sophistication level of these Middle Market companies in comparison to our LMM portfolio companies, it is not necessary or practical to have as much direct management interface.

We utilize an internally developed investment rating system to rate the performance of each LMM portfolio company and to monitor our expected level of returns on each of our LMM investments in relation to our expectations for the portfolio company. The investment rating system takes into consideration various factors, including, but not limited to, each investment's expected level of returns, the collectability of our debt investments and the ability to receive a return of the invested capital in our equity investments, comparisons to competitors and other industry participants, the portfolio company's future outlook and other factors that are deemed to be significant to the portfolio company.

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Exit Strategies/Refinancing

While we generally exit most investments through the refinancing or repayment of our debt and redemption or sale of our equity positions, we typically assist our LMM portfolio companies in developing and planning exit opportunities, including any sale or merger of our portfolio companies. We may also assist in the structure, timing, execution and transition of the exit strategy. The refinancing or repayment of Middle Market debt investments typically does not require our assistance due to the additional resources available to these larger, Middle Market companies.

DETERMINATION OF NET ASSET VALUE AND INVESTMENT PORTFOLIO VALUATION PROCESS

We determine the net asset value per share of our common stock on a quarterly basis. The net asset value per share is equal to our total assets minus total liabilities divided by the total number of shares of common stock outstanding.

We are required to report our investments at fair value. As a result, the most significant determination inherent in the preparation of our consolidated financial statements is the valuation of our Investment Portfolio and the related amounts of unrealized appreciation and depreciation. We follow the provisions of the Financial Accounting Standards Board Accounting Standards Codification ("ASC") 820, Fair Value Measurements and Disclosures ("ASC 820"). ASC 820 defines fair value, establishes a framework for measuring fair value, establishes a fair value hierarchy based on the quality of inputs used to measure fair value and enhances disclosure requirements for fair value measurements. ASC 820 requires us to assume that the portfolio investment is to be sold in the principal market to independent market participants, which may be a hypothetical market. Market participants are defined as buyers and sellers in the principal market that are independent, knowledgeable and willing and able to transact.

We determine in good faith the fair value of our Investment Portfolio pursuant to a valuation policy in accordance with ASC 820 and a valuation process approved by our Board of Directors and in accordance with the 1940 Act. Our valuation policies and processes are intended to provide a consistent basis for determining the fair value of our Investment Portfolio. See "Note B.1. — Valuation of the Investment Portfolio" in the notes to consolidated financial statements for a detailed discussion of our investment portfolio valuation process and procedures.

Due to the inherent uncertainty in the valuation process, our determination of fair value for our Investment Portfolio may differ materially from the values that would have been determined had a ready market for the securities existed. In addition, changes in the market environment, portfolio company performance and other events that may occur over the lives of the investments may cause the gains or losses ultimately realized on these investments to be materially different than the valuations currently assigned. We determine the fair value of each individual investment and record changes in fair value as unrealized appreciation or depreciation.

As described below, we undertake a multi-step valuation process each quarter in connection with determining the fair value of our investments, with our Board of Directors having final responsibility for overseeing, reviewing and approving, in good faith, our determination of the fair value for our Investment Portfolio and our valuation procedures, consistent with 1940 Act requirements. In addition, the Audit Committee of our Board of Directors periodically evaluates the performance and methodologies of the financial advisory services firm that we consult in connection with valuing our LMM and Private Loan portfolio company investments.

•

Our quarterly valuation process begins with each LMM and Private Loan portfolio company investment being initially valued by the investment team responsible for monitoring the portfolio investment;



•

The fair value determination for our Middle Market and Other Portfolio debt and equity investments and our investment in the External Investment Manager consists of unobservable and observable inputs

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which are initially reviewed by the investment professionals responsible for monitoring the portfolio investment;

•

Preliminary valuation conclusions are then reviewed by and discussed with senior management, and the investment team considers and assesses, as appropriate, any changes that may be required to the preliminary valuations to address any comments provided by senior management;



•

A nationally recognized independent financial advisory services firm analyzes and provides observations, recommendations and an assurance certification regarding the Company's determinations of the fair value for its LMM and Private Loan portfolio companies;



•

The Audit Committee of our Board of Directors reviews management's valuations, and the investment team and senior management consider and assess, as appropriate, any changes that may be required to management's valuations to address any comments provided by the Audit Committee; and



•

The Board of Directors assesses the valuations and ultimately approves the fair value of each investment in our portfolio in good faith.

Determination of fair value involves subjective judgments and estimates. The notes to our consolidated financial statements refer to the uncertainty with respect to the possible effect of such valuations, and any change in such valuations, on our financial results and financial condition.

COMPETITION

We compete for investments with a number of investment funds (including private equity funds, mezzanine funds, BDCs, and SBICs), as well as traditional financial services companies such as commercial banks and other sources of financing. Many of the entities that compete with us are larger and have more resources available to them. We believe we are able to be competitive with these entities primarily on the basis of our focus toward the underserved LMM, the experience and contacts of our management team, our responsive and efficient investment analysis and decision-making processes, our comprehensive suite of customized financing solutions and the investment terms we offer.

We believe that some of our competitors make senior secured loans, junior secured loans and subordinated debt investments with interest rates and returns that are comparable to or lower than the rates and returns that we target. Therefore, we do not seek to compete primarily on the interest rates and returns that we offer to potential portfolio companies. For additional information concerning the competitive risks we face, see "Risk Factors — Risks Relating to Our Business and Structure — We may face increasing competition for investment opportunities."

EMPLOYEES

As of December 31, 2018, we had 66 employees. These employees include investment and portfolio management professionals, operations professionals and administrative staff. As necessary, we will hire additional investment professionals and administrative personnel. All of our employees are located in our Houston, Texas office.

REGULATION

Regulation as a Business Development Company

We have elected to be regulated as a BDC under the 1940 Act. The 1940 Act contains prohibitions and restrictions relating to transactions between BDCs and their affiliates, principal underwriters and affiliates of those affiliates or underwriters. The 1940 Act requires that a majority of the members of the board of directors of a BDC be persons other than "interested persons," as that term is defined in the 1940 Act. In addition, the 1940 Act provides that we may not change the nature of our business so as to cease to be, or to withdraw our election as, a BDC unless approved by a majority of our outstanding voting securities.

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The 1940 Act defines "a majority of the outstanding voting securities" as the lesser of (i) 67% or more of the voting securities present at a meeting if the holders of more than 50% of our outstanding voting securities are present or represented by proxy or (ii) more than 50% of our outstanding voting securities.

Qualifying Assets

Under the 1940 Act, a BDC may not acquire any asset other than assets of the type listed in Section 55(a) of the 1940 Act, which are referred to as qualifying assets, unless, at the time the acquisition is made, qualifying assets represent at least 70% of the company's total assets. The principal categories of qualifying assets relevant to our business are any of the following:

(1)

Securities purchased in transactions not involving any public offering from the issuer of such securities, which issuer (subject to certain limited exceptions) is an eligible portfolio company (as defined below), or from any person who is, or has been during the preceding 13 months, an affiliated person of an eligible portfolio company, or from any other person, subject to such rules as may be prescribed by the SEC.



(2)

Securities of any eligible portfolio company that we control.



(3)

Securities purchased in a private transaction from a U.S. issuer that is not an investment company or from an affiliated person of the issuer, or in transactions incident thereto, if the issuer is in bankruptcy and subject to reorganization or if the issuer, immediately prior to the purchase of its securities was unable to meet its obligations as they came due without material assistance other than conventional lending or financing arrangements.



(4)

Securities of an eligible portfolio company purchased from any person in a private transaction if there is no ready market for such securities and we already own 60% of the outstanding equity of the eligible portfolio company.



(5)

Securities received in exchange for or distributed on or with respect to securities described in (1) through (4) above, or pursuant to the exercise of warrants or rights relating to such securities.



(6)

Cash, cash equivalents, U.S. government securities or high-quality debt securities maturing in one year or less from the time of investment.

In addition, a BDC must have been organized and have its principal place of business in the United States and must be operated for the purpose of making investments in the types of securities described in (1), (2) or (3) above.

An eligible portfolio company is defined in the 1940 Act as any issuer which:

(a)

is organized under the laws of, and has its principal place of business in, the United States;



(b)

is not an investment company (other than a small business investment company wholly owned by the BDC) or a company that would be an investment company but for certain exclusions under the 1940 Act; and



(c)

satisfies any of the following:



(i)

does not have any class of securities that is traded on a national securities exchange or has a class of securities listed on a national securities exchange but has an aggregate market value of outstanding voting and non-voting common equity of less than $250 million;



(ii)

is controlled by a BDC or a group of companies including a BDC and the BDC has an affiliated person who is a director of the eligible portfolio company; or



(iii)

is a small and solvent company having total assets of not more than $4 million and capital and surplus of not less than $2 million.

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Managerial Assistance to Portfolio Companies

As noted above, a BDC must be operated for the purpose of making investments in the type of securities described in (1), (2) or (3) above under the heading entitled "— Qualifying Assets." In addition, BDCs must generally offer to make available to such issuer of the securities (other than small and solvent companies described above) significant managerial assistance; except that, where we purchase such securities in conjunction with one or more other persons acting together, one of the other persons in the group may make available such managerial assistance. Making available managerial assistance means, among other things, any arrangement whereby the BDC, through its directors, officers or employees, offers to provide, and, if accepted, does so provide, significant guidance and counsel concerning the management, operations or business objectives and policies of a portfolio company.

Temporary Investments

Pending investment in "qualifying assets," as described above, our investments may consist of cash, cash equivalents, U.S. government securities and high-quality debt securities maturing in one year or less from time of investment therein, so that 70% of our assets are qualifying assets.

Senior Securities

Under the provisions of the 1940 Act, we are permitted, as a BDC, to issue senior securities only in amounts such that our asset coverage, as defined in the 1940 Act, equals at least 200% of all debt and/or senior stock immediately after each such issuance. However, recent legislation has modified the 1940 Act by allowing a BDC to increase the maximum amount of leverage it may incur from an asset coverage ratio of 200% to an asset coverage ratio of 150%, if certain requirements are met. We are permitted to increase our leverage capacity if stockholders representing at least a majority of the votes cast, when quorum is met, approve a proposal to do so. If we receive such stockholder approval, we would be permitted to increase our leverage capacity on the first day after such approval. Alternatively, we may increase the maximum amount of leverage we may incur to an asset coverage ratio of 150% if the "required majority" of our independent directors as defined in Section 57(o) of the 1940 Act approve such increase with such approval becoming effective after one year. In either case, we would be required to make certain disclosures on our website and in SEC filings regarding, among other things, the receipt of approval to increase our leverage, our leverage capacity and usage, and risks related to leverage. In addition, while any senior securities remain outstanding (other than senior securities representing indebtedness issued in consideration of a privately arranged loan which is not intended to be publicly distributed), we must make provisions to prohibit any distribution to our stockholders or the repurchase of such securities or shares unless we meet the applicable asset coverage ratios at the time of the distribution or repurchase. We may also borrow amounts up to 5% of the value of our total assets for temporary or emergency purposes without regard to asset coverage. For a discussion of the risks associated with leverage, see "Risk Factors — Risks Relating to Our Business and Structure," including, without limitation, "— Because we borrow money, the potential for gain or loss on amounts invested in us is magnified and may increase the risk of investing in us."

We have previously received an exemptive order from the SEC to exclude debt securities issued by MSMF and any other wholly owned subsidiaries of ours which operate as SBICs from the asset coverage requirements of the 1940 Act as applicable to Main Street. The exemptive order provides for the exclusion of all debt securities issued by the Funds, including the $345.8 million of outstanding debt as of December 31, 2018, issued pursuant to the SBIC program. This exemptive order provides us with expanded capacity and flexibility in obtaining future sources of capital for our investment and operational objectives.

Common Stock

We are not generally able to issue and sell our common stock at a price below net asset value per share. We may, however, sell our common stock, warrants, options or rights to acquire our common stock, at a price below the current net asset value of the common stock if our Board of Directors determines that such sale is

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in our best interests and that of our stockholders, and our stockholders approve such sale. In any such case, the price at which our securities are to be issued and sold may not be less than a price which, in the determination of our Board of Directors, closely approximates the market value of such securities (less any distributing commission or discount). We did not seek stockholder authorization to sell shares of our common stock below the then current net asset value per share of our common stock at our 2018 annual meeting of stockholders because our common stock price had been trading significantly above the net asset value per share of our common stock since 2011. Our stockholders have previously approved a proposal that authorizes us to issue securities to subscribe to, convert to, or purchase shares of our common stock in one or more offerings. We may also make rights offerings to our stockholders at prices per share less than the net asset value per share, subject to applicable requirements of the 1940 Act. See "Risk Factors — Risks Relating to Our Business and Structure — Stockholders may incur dilution if we sell shares of our common stock in one or more offerings at prices below the then current net asset value per share of our common stock or issue securities to subscribe to, convert to or purchase shares of our common stock."

Code of Ethics

We have adopted a code of ethics pursuant to Rule 17j-1 under the 1940 Act that establishes procedures for personal investments and restricts certain personal securities transactions. Personnel subject to the code may invest in securities for their personal investment accounts, including securities that may be purchased or held by us, so long as such investments are made in accordance with the code's requirements. In addition, the code of ethics is available on the EDGAR Database on the SEC's Web site at http://www.sec.gov.

Proxy Voting Policies and Procedures

We vote proxies relating to our portfolio securities in a manner in which we believe is consistent with the best interest of our stockholders. We review on a case-by-case basis each proposal submitted to a stockholder vote to determine its impact on the portfolio securities held by us. Although we generally vote against proposals that we expect would have a negative impact on our portfolio securities, we may vote for such a proposal if there exists compelling long-term reasons to do so.

Our proxy voting decisions are made by the investment team which is responsible for monitoring each of our investments. To ensure that our vote is not the product of a conflict of interest, we require that anyone involved in the decision-making process discloses to our chief compliance officer any potential conflict regarding a proxy vote of which he or she is aware.

Stockholders may obtain information, without charge, regarding how we voted proxies with respect to our portfolio securities by making a written request for proxy voting information to: Chief Compliance Officer, 1300 Post Oak Boulevard, 8th Floor, Houston, Texas 77056.

Other 1940 Act Regulations

We are also prohibited under the 1940 Act from knowingly participating in certain transactions with our affiliates without the prior approval of our Board of Directors who are not interested persons and, in some cases, prior approval by the SEC.

We are required to provide and maintain a bond issued by a reputable fidelity insurance company to protect us against larceny and embezzlement. Furthermore, as a BDC, we are prohibited from protecting any director or officer against any liability to us or our stockholders arising from willful misfeasance, bad faith, gross negligence or reckless disregard of the duties involved in the conduct of such person's office.

We are required to adopt and implement written policies and procedures reasonably designed to prevent violation of the federal securities laws, review these policies and procedures no less frequently than annually for their adequacy and the effectiveness of their implementation, and to designate a chief compliance officer to be responsible for administering the policies and procedures.

We may be periodically examined by the SEC for compliance with the 1940 Act.

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Small Business Investment Company Regulations

Each of the Funds is licensed by the SBA to operate as a SBIC under Section 301(c) of the Small Business Investment Act of 1958. MSMF obtained its SBIC license in 2002, MSC II obtained its license in 2006 and MSC III obtained its license in 2016.

SBICs are designed to stimulate the flow of private capital to eligible small businesses. Under SBIC regulations, SBICs may make loans to eligible small businesses, invest in the equity securities of such businesses and provide them with consulting and advisory services. Each of the Funds has typically invested in secured debt, acquired warrants and/or made equity investments in qualifying small businesses.

The Funds are subject to regulation and oversight by the SBA, including requirements with respect to reporting financial information, such as the extent of capital impairment if applicable, on a regular basis and annual examinations conducted by the SBA. The SBA, as a creditor, will have a superior claim to the Funds' assets over our securities holders in the event the Funds are liquidated or the SBA exercises its remedies under the SBA-guaranteed debentures issued by the Funds upon an event of default.

We have received exemptive relief from the SEC to permit us to exclude the SBA-guaranteed debentures of the Funds from our 200% asset coverage test under the 1940 Act. As such, our ratio of total consolidated assets to outstanding indebtedness may be less than 200%. This provides us with increased investment flexibility but also increases our risks related to leverage. See "Risk Factors — Risks Relating to Our Business and Structure — Because we borrow money, the potential for gain or loss on amounts invested in us is magnified and may increase the risk of investing in us."

Under present SBIC regulations, eligible small businesses generally include businesses that (together with their affiliates) have a tangible net worth not exceeding $19.5 million or have average annual net income after U.S. federal income taxes not exceeding $6.5 million (average net income to be computed without benefit of any carryover loss) for the two most recent fiscal years. In addition, an SBIC must devote 25% of its investment activity to "smaller" enterprises as defined by the SBA. A smaller enterprise generally includes businesses that have a tangible net worth not exceeding $6 million and have average annual net income after U.S. federal income taxes not exceeding $2 million (average net income to be computed without benefit of any net carryover loss) for the two most recent fiscal years. SBIC regulations also provide alternative size standard criteria to determine eligibility for designation as an eligible small business or smaller enterprise, which criteria depend on the primary industry in which the business is engaged and are based on such factors as the number of employees and gross revenue. However, once an SBIC has invested in a company, it generally may continue to make follow-on investments in the company, regardless of the size of the portfolio company at the time of the follow-on investment, up to the time of the portfolio company's initial public offering.

The SBA prohibits an SBIC from providing funds to small businesses for certain purposes, such as relending and investment outside the United States, to businesses engaged in certain prohibited industries, and to certain "passive" (non-operating) companies. In addition, without prior SBA approval, an SBIC may not invest an amount equal to more than approximately 30% of the SBIC's regulatory capital, as defined by the SBA, in any one portfolio company and its affiliates.

The SBA places certain limitations on the financing terms of investments by SBICs in portfolio companies (such as limiting the permissible interest rate on debt securities held by an SBIC in a portfolio company). Included in such limitations are SBA regulations which allow an SBIC to exercise control over a small business for a period of seven years from the date on which the SBIC initially acquires its control position. This control period may be extended for an additional period of time with the SBA's prior written approval.

The SBA restricts the ability of an SBIC to lend money to any of its officers, directors and employees or to invest in affiliates thereof. The SBA also prohibits, without prior SBA approval, a "change of control" of an SBIC or transfers that would result in any person (or a group of persons acting in concert) owning 10% or more of a class of equity of a licensed SBIC. A "change of control" is any event which would result in the

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transfer of the power, direct or indirect, to direct the management and policies of an SBIC, whether through ownership, contractual arrangements or otherwise.

The SBIC licenses allow the Funds to incur leverage by issuing SBA-guaranteed debentures, subject to the issuance of a capital commitment and certain approvals by the SBA and customary procedures. SBA-guaranteed debentures carry long-term fixed rates that are generally lower than rates on comparable bank and other debt. Under applicable regulations, an SBIC may generally have outstanding debentures guaranteed by the SBA in amounts up to twice the amount of the privately raised funds of the SBIC. Debentures guaranteed by the SBA have a maturity of ten years, require semiannual payments of interest, do not require any principal payments prior to maturity, and are not subject to prepayment penalties. As of December 31, 2018, we, through the Funds, had $345.8 million of outstanding SBA-guaranteed debentures, which had an annual weighted-average interest rate of approximately 3.7%.

SBICs must invest idle funds that are not being used to make loans in investments permitted under SBIC regulations in the following limited types of securities: (i) direct obligations of, or obligations guaranteed as to principal and interest by, the United States government, which mature within 15 months from the date of the investment; (ii) repurchase agreements with federally insured institutions with a maturity of seven days or less (and the securities underlying the repurchase obligations must be direct obligations of or guaranteed by the federal government); (iii) certificates of deposit with a maturity of one year or less, issued by a federally insured institution; (iv) a deposit account in a federally insured institution that is subject to a withdrawal restriction of one year or less; (v) a checking account in a federally insured institution; or (vi) a reasonable petty cash fund.

SBICs are periodically examined and audited by the SBA's staff to determine their compliance with SBIC regulations and are periodically required to file certain financial information and other documents with the SBA.

Neither the SBA nor the U.S. government or any of its agencies or officers has approved any ownership interest to be issued by us or any obligation that we or any of our subsidiaries may incur.

Securities Exchange Act of 1934 and Sarbanes-Oxley Act Compliance

We are subject to the reporting and disclosure requirements of the Securities Exchange Act of 1934 (the "Exchange Act"), including the filing of quarterly, annual and current reports, proxy statements and other required items. In addition, we are subject to the Sarbanes-Oxley Act of 2002, which imposes a wide variety of regulatory requirements on publicly-held companies and their insiders. For example:

•

pursuant to Rule 13a-14 of the Exchange Act, our Chief Executive Officer and Chief Financial Officer are required to certify the accuracy of the consolidated financial statements contained in our periodic reports;



•

pursuant to Item 307 of Regulation S-K, our periodic reports are required to disclose our conclusions about the effectiveness of our disclosure controls and procedures;



•

pursuant to Rule 13a-15 of the Exchange Act, our management is required to prepare a report regarding its assessment of our internal control over financial reporting, and our independent registered public accounting firm separately audits our internal control over financial reporting; and



•

pursuant to Item 308 of Regulation S-K and Rule 13a-15 of the Exchange Act, our periodic reports must disclose whether there were significant changes in our internal control over financial reporting or in other factors that could significantly affect these controls subsequent to the date of their evaluation, including any corrective actions with regard to significant deficiencies and material weaknesses.

The New York Stock Exchange Corporate Governance Regulations

The New York Stock Exchange ("NYSE") has adopted corporate governance regulations that listed companies must comply with. We believe we are in compliance with such corporate governance listing

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standards. We intend to monitor our compliance with all future listing standards and to take all necessary actions to ensure that we stay in compliance.

Investment Adviser Regulations

The External Investment Manager, which is wholly owned by us, is subject to regulation under the Advisers Act. The Advisers Act establishes, among other things, recordkeeping and reporting requirements, disclosure requirements, limitations on transactions between the adviser's account and an advisory client's account, limitations on transactions between the accounts of advisory clients, and general anti-fraud prohibitions. The External Investment Manager may be examined by the SEC from time to time for compliance with the Advisers Act.

Taxation as a Regulated Investment Company

MSCC has elected to be treated for U.S. federal income tax purposes as a RIC under Subchapter M of the Code. MSCC's taxable income includes the taxable income generated by MSCC and certain of its subsidiaries, including the Funds, which are treated as disregarded entities for tax purposes. As a RIC, we generally will not pay corporate-level U.S. federal income taxes on any income that we distribute to our stockholders as dividends. To qualify as a RIC, we must, among other things, meet certain source-of-income and asset diversification requirements (as described below). In addition, in order to obtain RIC tax treatment, we must distribute to our stockholders, for each taxable year, at least 90% of our "investment company taxable income," which is generally our net ordinary taxable income plus the excess of realized net short-term capital gains over realized net long-term capital losses, and 90% of our tax-exempt income (the "Annual Distribution Requirement"). As part of maintaining RIC status, undistributed taxable income (subject to a 4% non-deductible U.S. federal excise tax) pertaining to a given fiscal year may be distributed up to 12 months subsequent to the end of that fiscal year, provided such dividends are declared on or prior to the later of (i) filing of the U.S. federal income tax return for the applicable fiscal year or (ii) the fifteenth day of the ninth month following the close of the year in which such taxable income was generated.

For any taxable year in which we qualify as a RIC and satisfy the Annual Distribution Requirement, we will not be subject to U.S. federal income tax on the portion of our income or capital gains we distribute (or are deemed to distribute) to stockholders. We will be subject to U.S. federal income tax at the regular corporate rates on any income or capital gains not distributed (or deemed distributed) to our stockholders.

We are subject to a 4% non-deductible U.S. federal excise tax on certain undistributed income unless we distribute in a timely manner an amount at least equal to the sum of (1) 98% of our net ordinary taxable income for each calendar year, (2) 98.2% of our capital gain net income for the one-year period ending December 31 in that calendar year and (3) any taxable income recognized, but not distributed, in preceding years on which we paid no U.S. federal income tax (the "Excise Tax Avoidance Requirement"). Dividends declared and paid by us in a year will generally differ from taxable income for that year as such dividends may include the distribution of current year taxable income, exclude amounts carried over into the following year, and include the distribution of prior year taxable income carried over into and distributed in the current year. For amounts we carry over into the following year, we will be required to pay the 4% U.S. federal excise tax on the excess of 98% of our annual investment company taxable income and 98.2% of our capital gain net income over our distributions for the year.

In order to qualify as a RIC for U.S. federal income tax purposes, we must, among other things:

•

continue to qualify as a BDC under the 1940 Act at all times during each taxable year;



•

derive in each taxable year at least 90% of our gross income from dividends, interest, payments with respect to certain securities, loans, gains from the sale of stock or other securities, net income from certain "qualified publicly traded partnerships," or other income derived with respect to our business of investing in such stock or securities (the "90% Income Test"); and

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•

diversify our holdings so that at the end of each quarter of the taxable year:



•

at least 50% of the value of our assets consists of cash, cash equivalents, U.S. government securities, securities of other RICs, and other securities if such other securities of any one issuer do not represent more than 5% of the value of our assets or more than 10% of the outstanding voting securities of the issuer; and



•

no more than 25% of the value of our assets is invested in the securities, other than U.S. government securities or securities of other RICs, (i) of one issuer, (ii) of two or more issuers that are controlled, as determined under applicable Code rules, by us and that are engaged in the same or similar or related trades or businesses or (iii) of certain "qualified publicly traded partnerships" (collectively, the "Diversification Tests").

In order to comply with the 90% Income Test, we formed the Taxable Subsidiaries as wholly owned taxable subsidiaries for the primary purpose of permitting us to own equity interests in portfolio companies which are "pass-through" entities for tax purposes. Absent the taxable status of the Taxable Subsidiaries, a portion of the gross income from such portfolio companies would flow directly to us for purposes of the 90% Income Test. To the extent such income did not consist of income derived from securities, such as dividends and interest, it could jeopardize our ability to qualify as a RIC and, therefore, cause us to incur significant U.S. federal income taxes. The Taxable Subsidiaries are consolidated with Main Street for generally accepted accounting principles in the United States of America ("U.S. GAAP") purposes and are included in our consolidated financial statements, and the portfolio investments held by the Taxable Subsidiaries are included in our consolidated financial statements. The Taxable Subsidiaries are not consolidated with Main Street for income tax purposes and may generate income tax expense, or benefit, as a result of their ownership of the portfolio investments. The income tax expense, or benefit, if any, and any related tax assets and liabilities, are reflected in our consolidated financial statements.

The External Investment Manager is accounted for as a portfolio investment for U.S. GAAP purposes and is an indirect wholly owned subsidiary of MSCC, owned through a Taxable Subsidiary. The External Investment Manager is owned by a Taxable Subsidiary in order to comply with the 90% Income Test, since the External Investment Manager's income would likely not consist of income derived from securities, such as dividends and interest, and as result, it could jeopardize our ability to qualify as a RIC and, therefore, cause us to incur significant U.S. federal income taxes. As a result of its ownership by a Taxable Subsidiary, the External Investment Manager is a disregarded entity for tax purposes. The External Investment Manager has also entered into a tax sharing agreement with its Taxable Subsidiary owner. Since the External Investment Manager is accounted for as a portfolio investment of MSCC and is not included as a consolidated subsidiary of MSCC in MSCC's consolidated financial statements, and as a result of the tax sharing agreement with its Taxable Subsidiary owner, for its stand-alone financial reporting purposes the External Investment Manager is treated as if it is taxed at normal corporate tax rates based on its taxable income and, as a result of its activities, may generate income tax expense or benefit. The income tax expense, or benefit, if any, and the related tax assets and liabilities, of the External Investment Manager are reflected in the External Investment Manager's separate financial statements.

We may be required to recognize taxable income in circumstances in which we do not receive cash. For example, if we hold debt obligations that are treated under applicable tax rules as having original issue discount (such as debt instruments issued with warrants and debt securities invested in at a discount to par), we must include in income each year a portion of the original issue discount that accrues over the life of the obligation, regardless of whether cash representing such income is received by us in the same taxable year. We may also have to include in income other amounts that we have not yet received in cash such as PIK interest, cumulative dividends or amounts that are received in non-cash compensation such as warrants or stock. Because any original issue discount or other amounts accrued will be included in our investment company taxable income for the year of accrual, we may be required to make a distribution to our stockholders in order to satisfy the Annual Distribution Requirement, even though we will not have received any corresponding cash amount.

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Although we do not presently expect to do so, we are authorized to borrow funds and to sell assets in order to satisfy distribution requirements. However, under the 1940 Act, we are not permitted to make distributions to our stockholders in certain circumstances while our debt obligations and other senior securities are outstanding unless certain "asset coverage" tests are met. See "Regulation — Regulation as a Business Development Company — Senior Securities." Moreover, our ability to dispose of assets to meet our distribution requirements may be limited by (1) the illiquid nature of our portfolio and/or (2) other requirements relating to our status as a RIC, including the Diversification Tests. If we dispose of assets in order to meet the Annual Distribution Requirement or the Excise Tax Avoidance Requirement, we may make such dispositions at times that, from an investment standpoint, are not advantageous.

We may distribute taxable dividends that are payable in part in our stock. Under certain applicable provisions of the Code and the U.S. Department of the Treasury ("Treasury") regulations, distributions payable by us in cash or in shares of stock (at the stockholders election) would satisfy the Annual Distribution Requirement. The Internal Revenue Service has issued guidance indicating that this rule will apply even where the total amount of cash that may be distributed is limited to no more than 20% of the total distribution. According to this guidance, if too many stockholders elect to receive their distributions in cash, each such stockholder would receive a pro rata share of the total cash to be distributed and would receive the remainder of their distribution in shares of stock. Taxable stockholders receiving such dividends will be required to include the full amount of the dividend (whether received in cash, our stock, or a combination thereof) as (i) ordinary income (including any qualified dividend income that, in the case of a noncorporate stockholder, may be eligible for the same reduced maximum tax rate applicable to long-term capital gains to the extent such distribution is properly reported by us as qualified dividend income and such stockholder satisfies certain minimum holding period requirements with respect to our stock) or (ii) long-term capital gain (to the extent such distribution is properly reported as a capital gain dividend), to the extent of our current and accumulated earnings and profits for U.S. federal income tax purposes. As a result, a U.S. stockholder may be required to pay tax with respect to such dividends in excess of any cash received. If a U.S. stockholder sells the stock it receives in order to pay this tax, the sales proceeds may be less than the amount included in income with respect to the dividend, depending on the market price of our stock at the time of the sale. Furthermore, with respect to non-U.S. stockholders, we may be required to withhold U.S. tax with respect to such dividends, including in respect of all or a portion of such dividend that is payable in stock. In addition, if a significant number of our stockholders determine to sell shares of our stock in order to pay taxes owed on dividends, it may put downward pressure on the trading price of our stock.

Failure to Qualify as a RIC

If we fail to satisfy the 90% Income Test or the Diversification Tests for any taxable year, we may nevertheless continue to qualify as a RIC for such year if certain relief provisions are applicable (which may, among other things, require us to pay certain corporate-level U.S. federal taxes or to dispose of certain assets).

If we were unable to qualify for treatment as a RIC and the foregoing relief provisions are not applicable, we would be subject to tax on all of our taxable income at regular corporate rates. We would not be able to deduct distributions to stockholders, nor would they be required to be made. If we were subject to tax on all of our taxable income at regular corporate rates, then distributions we make after being subject to such tax would be taxable to our stockholders and, provided certain holding period and other requirements were met, could qualify for treatment as "qualified dividend income" eligible for the maximum 20% rate (plus a 3.8% Medicare surtax, if applicable) applicable to qualified dividends to the extent of our current and accumulated earnings and profits. Subject to certain limitations under the Code, corporate taxpayers would be eligible for a dividends-received deduction on distributions they receive. Distributions in excess of our current and accumulated earnings and profits would be treated first as a return of capital to the extent of the stockholder's tax basis, and any remaining distributions would be treated as a capital gain. To requalify as a RIC in a subsequent taxable year, we would be required to satisfy the RIC qualification requirements for that year and dispose of any earnings and profits from any year in which we failed to qualify as a RIC. Subject to a

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limited exception applicable to RICs that qualified as such under Subchapter M of the Code for at least one year prior to disqualification and that requalify as a RIC no later than the second year following the nonqualifying year, we could be subject to tax on any unrealized net built-in gains in the assets held by us during the period in which we failed to qualify as a RIC that are recognized within the subsequent five years, unless we made a special election to pay corporate-level U.S. federal income tax on such built-in gain at the time of our requalification as a RIC.

Item 1A. Risk Factors

Investing in our securities involves a number of significant risks. In addition to the other information contained in this Annual Report on Form 10-K, you should consider carefully the following information before making an investment in our securities. The risks set out below are not the only risks we face. Additional risks and uncertainties not presently known to us or not presently deemed material by us might also impair our operations and performance. If any of the following events occur, our business, financial condition and results of operations could be materially and adversely affected. In such case, our net asset value, the trading price of our common stock and the value of our other securities could decline, and you may lose all or part of your investment.

RISKS RELATING TO ECONOMIC CONDITIONS

Deterioration in the economy and financial markets increases the likelihood of adverse effects on our financial position and results of operations. Such economic adversity could impair our portfolio companies' financial positions and operating results and affect the industries in which we invest, which could, in turn, harm our operating results.

The broader fundamentals of the United States economy remain mixed. In the event that the United States economy contracts, it is likely that the financial results of small to mid-sized companies, like those in which we invest, could experience deterioration or limited growth from current levels, which could ultimately lead to difficulty in meeting their debt service requirements and an increase in defaults. In addition, a decline in oil and natural gas prices would adversely affect the credit quality of our debt investments and the underlying operating performance of our equity investments in energy-related businesses. Consequently, we can provide no assurance that the performance of certain portfolio companies will not be negatively impacted by economic cycles, industry cycles or other conditions, which could also have a negative impact on our future results.

Although we have been able to secure access to additional liquidity, including through our multi-year revolving credit facility (the "Credit Facility"), public debt issuances, leverage available through the SBIC program and equity offerings, the potential for volatility in the debt and equity capital markets provides no assurance that debt or equity capital will be available to us in the future on favorable terms, or at all. Further, if the price of our common stock falls below our net asset value per share, we will be limited in our ability to sell new shares if we do not have stockholder authorization to sell shares at a price below net asset value per share. We did not seek stockholder authorization to sell shares of our common stock below the then current net asset value per share of our common stock at our 2018 annual meeting of stockholders because our common stock price had been trading significantly above the net asset value per share of our common stock since 2011.

Global capital markets could enter a period of severe disruption and instability. These conditions have historically affected and could again materially and adversely affect debt and equity capital markets in the United States, which could have a materially negative impact on our business, financial condition and results of operations.

The U.S. and global capital markets have, from time to time, experienced periods of disruption characterized by the freezing of available credit, a lack of liquidity in the debt capital markets, significant losses in the principal value of investments, the re-pricing of credit risk in the broadly syndicated credit

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market, the failure of major financial institutions and general volatility in the financial markets. During these periods of disruption, general economic conditions deteriorated with material and adverse consequences for the broader financial and credit markets, and the availability of debt and equity capital for the market as a whole, and financial services firms in particular, was reduced significantly. These conditions may reoccur for a prolonged period of time or materially worsen in the future. In addition, continuing uncertainty arising from the United Kingdom's decision to leave the European Union (the so called "Brexit") could lead to further market disruptions and currency volatility, potentially weakening consumer, corporate and financial confidence and resulting in lower economic growth for companies that rely significantly on Europe for their business activities and revenues. We may in the future have difficulty accessing debt and equity capital markets, and a severe disruption in the global financial markets, deterioration in credit and financing conditions or uncertainty regarding U.S. government spending and deficit levels, Brexit or other global economic conditions could have a material adverse effect on our business, financial condition and results of operations.

RISKS RELATING TO OUR BUSINESS AND STRUCTURE

Our Investment Portfolio is and will continue to be recorded at fair value, with our Board of Directors having final responsibility for overseeing, reviewing and approving, in good faith, our determination of fair value and, as a result, there is and will continue to be uncertainty as to the value of our portfolio investments.

Under the 1940 Act, we are required to carry our portfolio investments at market value or, if there is no readily available market value, at fair value as determined by us with our Board of Directors having final responsibility for overseeing, reviewing and approving, in good faith, our determination of fair value and our valuation procedures. Typically, there is not a public market for the securities of the privately held LMM or Private Loan companies in which we have invested and will generally continue to invest. As a result, we value these securities quarterly at fair value based on inputs from management, a nationally recognized independent financial advisory services firm (on a rotational basis) and our audit committee with the oversight, review and approval of our Board of Directors. In addition, the market for investments in Middle Market companies is generally not a liquid market, and therefore, we primarily use a combination of observable inputs in non-active markets for which sufficient observable inputs were not available to determine the fair value of these investments and unobservable inputs, which are reviewed by our audit committee with the oversight, review and approval of our Board of Directors. See "Note B.1. — Valuation of the Investment Portfolio" in the notes to consolidated financial statements for a more detailed description of our investment portfolio valuation process and procedures.

The determination of fair value and consequently, the amount of unrealized gains and losses in our portfolio, are to a certain degree, subjective and dependent on a valuation process approved by our Board of Directors. Certain factors that may be considered in determining the fair value of our investments include external events, such as private mergers, sales and acquisitions involving comparable companies. Because such valuations, and particularly valuations of securities in privately held companies, are inherently uncertain, may fluctuate over short periods of time and may be based on estimates, our determinations of fair value may differ materially from the values that would have been used if a ready market for these securities existed. Due to this uncertainty, our fair value determinations may cause our net asset value on a given date to materially understate or overstate the value that we may ultimately realize on one or more of our investments. As a result, investors purchasing our securities based on an overstated net asset value would pay a higher price than the value of our investments might warrant. Conversely, investors selling our securities during a period in which the net asset value understates the value of our investments may receive a lower price for their securities than the value of our investments might warrant.

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Our financial condition and results of operations depends on our ability to effectively manage and deploy capital.

Our ability to achieve our investment objective of maximizing our portfolio's total return by generating current income from our debt investments and capital appreciation from our equity and equity-related investments, including warrants, convertible securities and other rights to acquire equity securities in a portfolio company, depends on our ability to effectively manage and deploy capital, which depends, in turn, on our investment team's ability to identify, evaluate and monitor, and our ability to finance and invest in, companies that meet our investment criteria.

Accomplishing our investment objective on a cost-effective basis is largely a function of our investment team's handling of the investment process, its ability to provide competent, attentive and efficient services and our access to investments offering acceptable terms. In addition to monitoring the performance of our existing investments, members of our investment team are also called upon, from time to time, to provide managerial assistance to some of our portfolio companies. These demands on their time may distract them or slow the rate of investment.

Even if we are able to grow and build upon our investment operations, any failure to manage our growth effectively could have a material adverse effect on our business, financial condition, results of operations and prospects. The results of our operations will depend on many factors, including the availability of opportunities for investment, readily accessible short and long-term funding alternatives in the financial markets and economic conditions. Furthermore, if we cannot successfully operate our business or implement our investment policies and strategies as described herein, it could negatively impact our ability to pay dividends.

We may face increasing competition for investment opportunities.

We compete for investments with other investment funds (including private equity funds, debt funds, mezzanine funds, collateralized loan obligation funds, or CLOs, BDCs, and SBICs), as well as traditional financial services companies such as commercial banks and other sources of funding. Many of our competitors are substantially larger and have considerably greater financial, technical and marketing resources than we do. For example, some competitors may have a lower cost of capital and access to funding sources that are not available to us. In addition, some of our competitors may have higher risk tolerances or different risk assessments than we have. These characteristics could allow our competitors to consider a wider variety of investments, establish more relationships and offer better pricing and more flexible structuring than we are able to do. We may lose investment opportunities if we do not match our competitors' pricing, terms and structure. If we are forced to match our competitors' pricing, terms and structure, we may not be able to achieve acceptable returns on our investments or may bear substantial risk of capital loss. A significant part of our competitive advantage stems from the fact that the market for investments in LMM companies is underserved by traditional commercial banks and other financing sources. A significant increase in the number and/or the size of our competitors in this target market could force us to accept less attractive investment terms. Furthermore, many of our competitors are not subject to the regulatory restrictions that the 1940 Act imposes on us as a BDC.

We are dependent upon our key investment personnel for our future success.

We depend on the members of our investment team, particularly Dwayne L. Hyzak, David L. Magdol, Vincent D. Foster, Curtis L. Hartman, K. Colton Braud, III, Nicholas T. Meserve, Samuel A. Cashiola and Watt R. Matthews, for the identification, review, final selection, structuring, closing and monitoring of our investments. These employees have significant investment expertise and relationships that we rely on to implement our business plan. Although we have entered into a non-compete agreement with Mr. Foster and non-compete arrangements with all of our executive officers and other key employees in connection with their restricted stock grants, we have no guarantee that he or any other employees will remain employed with us. If

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we lose the services of these individuals, we may not be able to operate our business as we expect, and our ability to compete could be harmed, which could cause our operating results to suffer.

Our success depends on attracting and retaining qualified personnel in a competitive environment.

Our growth will require that we retain new investment and administrative personnel in a competitive market. Our ability to attract and retain personnel with the requisite credentials, experience and skills depends on several factors including, but not limited to, our ability to offer competitive wages, benefits and professional growth opportunities. Many of the entities, including investment funds (such as private equity funds, debt funds and mezzanine funds) and traditional financial services companies, with which we compete for experienced personnel have greater resources than we have.

The competitive environment for qualified personnel may require us to take certain measures to ensure that we are able to attract and retain experienced personnel. Such measures may include increasing the attractiveness of our overall compensation packages, altering the structure of our compensation packages through the use of additional forms of compensation, or other steps. The inability to attract and retain experienced personnel would have a material adverse effect on our business.

Our business model depends to a significant extent upon strong referral relationships, and our inability to maintain or develop these relationships, as well as the failure of these relationships to generate investment opportunities, could adversely affect our business.

We expect that members of our management team will maintain their relationships with intermediaries, financial institutions, investment bankers, commercial bankers, financial advisors, attorneys, accountants, consultants and other individuals within our network, and we will rely to a significant extent upon these relationships to provide us with potential investment opportunities. If our management team fails to maintain its existing relationships or develop new relationships with sources of investment opportunities, we will not be able to grow our Investment Portfolio. In addition, individuals with whom members of our management team have relationships are not obligated to provide us with investment opportunities, and, therefore, there is no assurance that such relationships will generate investment opportunities for us.

Our executive officers and employees, through the External Investment Manager, may manage other investment funds, including HMS Income, that operate in the same or a related line of business as we do, which may result in significant conflicts of interest.

Our executive officers and employees, through the External Investment Manager, may manage other investment funds that operate in the same or a related line of business as we do. Accordingly, they may have obligations to such other entities, the fulfillment of which obligations may not be in the best interests of us or our stockholders. During May 2012, we entered into an investment sub-advisory agreement with HMS Adviser, which is the investment advisor to HMS Income, a non-listed BDC, to provide certain investment advisory services to HMS Adviser. In December 2013, after obtaining required no-action relief from the SEC to allow us to own a registered investment adviser, we assigned the sub-advisory agreement to the External Investment Manager since the fees received from such arrangement could otherwise have negative consequences on our ability to meet the source-of-income requirement necessary for us to maintain our RIC tax treatment. Under the investment sub-advisory agreement, the External Investment Manager is entitled to 50% of the base management fee and the incentive fees earned by HMS Adviser under its advisory agreement with HMS Income. The sub-advisory relationship requires us to commit resources to achieving HMS Income's investment objective, while such resources were previously solely devoted to achieving our investment objective. Our investment objective and investment strategies are very similar to those of HMS Income and it is likely that an investment appropriate for us or HMS Income would be appropriate for the other entity. As a result, we and HMS Income requested an exemptive order from the SEC permitting co-investments by us and HMS Income in certain negotiated transactions where our co-investing would otherwise be prohibited under the 1940 Act. The SEC granted the exemptive order in April 2014, and we have made, and in the future intend to continue to make, such co-investments with HMS Income in

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accordance with the conditions of the order. The order requires, among other things, that we and the External Investment Manager consider whether each such investment opportunity is appropriate for HMS Income and, if it is appropriate, to propose an allocation of the investment opportunity between us and HMS Income. As a consequence, it may be more difficult for us to maintain or increase the size of our Investment Portfolio in the future. Although we will endeavor to allocate investment opportunities in a fair and equitable manner, including in accordance with the conditions set forth in the exemptive order issued by the SEC when relying on such order, we may face conflicts in allocating investment opportunities between us and HMS Income. Because the External Investment Manager may receive performance-based fee compensation from HMS Income, this may provide an incentive to allocate opportunities to HMS Income instead of us. We have implemented an allocation policy to ensure the equitable distribution of investment opportunities and, as a result, may be unable to participate in certain investments based upon such allocation policy.

We, through the External Investment Manager, derive revenues from managing third party funds pursuant to management agreements that may be terminated pursuant to the terms of such agreements or requirements under the 1940 Act.

The External Investment Manager earns management fees based on the assets of the funds under management and may earn incentive fees, or a carried interest, based on the performance of the funds managed, including HMS Income. The terms of fund investment management agreements generally give the manager of the fund and the fund itself the right to terminate the management agreement in certain circumstances. With respect to funds that are not exempt from regulation under the 1940 Act, the fund's investment management agreement must be approved annually by (a) such fund's board of directors or by the vote of a majority of such fund's stockholders and (b) the majority of the independent members of such fund's board of directors and, in certain cases, by its stockholders, as required by law. The funds' investment management agreements can also be terminated by the majority of such fund's stockholders. Termination of any such management agreements would reduce the fees we earn from the relevant funds through the External Investment Manager, which could have a material adverse effect on our results of operations. Currently, HMS Income, an investment company that has elected to be regulated as a business development company under the 1940 Act, is subject to these provisions of the 1940 Act.

Regulations governing our operation as a BDC will affect our ability to, and the way in which we, raise additional capital.

Our business will require capital to operate and grow. We may acquire such additional capital from the following sources:

Senior Securities. We may issue debt securities or preferred stock and/or borrow money from banks or other financial institutions, which we refer to collectively as senior securities. As a result of issuing senior securities, we will be exposed to additional risks, including the following:

•

Under the provisions of the 1940 Act, we are permitted, as a BDC, to issue senior securities only in amounts such that our asset coverage, as defined in the 1940 Act, equals at least 200% (or 150% if certain requirements are met) immediately after each issuance of senior securities. We have received exemptive relief from the SEC to permit us to exclude the SBA-guaranteed debentures of the Funds from our asset coverage test under the 1940 Act. If the value of our assets declines, we may be unable to satisfy this test. If that happens, we will be prohibited from issuing debt securities or preferred stock and/or borrowing money from banks or other financial institutions and may not be permitted to declare a dividend or make any distribution to stockholders or repurchase shares until such time as we satisfy this test.



•

Any amounts that we use to service our debt or make payments on preferred stock will not be available for dividends to our common stockholders.



•

It is likely that any senior securities or other indebtedness we issue will be governed by an indenture or other instrument containing covenants restricting our operating flexibility.

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Additionally, some of these securities or other indebtedness may be rated by rating agencies, and in obtaining a rating for such securities and other indebtedness, we may be required to abide by operating and investment guidelines that further restrict operating and financial flexibility.

•

We and, indirectly, our stockholders will bear the cost of issuing and servicing such securities and other indebtedness.



•

Preferred stock or any convertible or exchangeable securities that we issue in the future may have rights, preferences and privileges more favorable than those of our common stock, including separate voting rights and could delay or prevent a transaction or a change in control to the detriment of the holders of our common stock.



•

Any unsecured debt issued by us would rank (i) pari passu with our current and future unsecured indebtedness and effectively subordinated to all of our existing and future secured indebtedness, to the extent of the value of the assets securing such indebtedness, and (ii) structurally subordinated to all existing and future indebtedness and other obligations of any of our subsidiaries, including the SBA-guaranteed debentures issued by the Funds.

Additional Common Stock. The 1940 Act prohibits us from selling shares of our common stock at a price below the current net asset value per share of such stock, with certain exceptions. One such exception is prior stockholder approval of issuances below current net asset value per share provided that our Board of Directors makes certain determinations. We did not seek stockholder authorization to sell shares of our common stock below the then current net asset value per share of our common stock at our 2018 annual meeting of stockholders because our common stock price had been trading significantly above the net asset value per share of our common stock since 2011. We may, however, sell our common stock, warrants, options or rights to acquire our common stock, at a price below the current net asset value of the common stock if our Board of Directors determines that such sale is in the best interests of our stockholders, and our stockholders approve such sale. See "— Stockholders may incur dilution if we sell shares of our common stock in one or more offerings at prices below the then current net asset value per share of our common stock or issue securities to subscribe to, convert to or purchase shares of our common stock" for a discussion of the risks related to us issuing shares of our common stock below net asset value. Our stockholders have authorized us to issue warrants, options or rights to subscribe for, convert to, or purchase shares of our common stock at a price per share below the net asset value per share, subject to the applicable requirements of the 1940 Act. There is no expiration date on our ability to issue such warrants, options, rights or convertible securities based on this stockholder approval. If we raise additional funds by issuing more common stock or senior securities convertible into, or exchangeable for, our common stock, the percentage ownership of our stockholders at that time would decrease, and they may experience dilution. Moreover, we can offer no assurance that we will be able to issue and sell additional equity securities in the future, on favorable terms or at all.

The Funds are licensed by the SBA, and therefore subject to SBA regulations.

The Funds, our wholly owned subsidiaries, are licensed to act as SBICs and are regulated by the SBA. The SBA also places certain limitations on the financing terms of investments by SBICs in portfolio companies and prohibits SBICs from providing funds for certain purposes or to businesses in a few prohibited industries. Compliance with SBA requirements may cause the Funds to forego attractive investment opportunities that are not permitted under SBA regulations.

Further, the SBA regulations require, among other things, that a licensed SBIC be periodically examined by the SBA and audited by an independent auditor, in each case to determine the SBIC's compliance with the relevant SBA regulations. The SBA prohibits, without prior SBA approval, a "change of control" of an SBIC or transfers that would result in any person (or a group of persons acting in concert) owning 10% or more of a class of capital stock of a licensed SBIC. If the Funds fail to comply with applicable SBIC regulations, the SBA could, depending on the severity of the violation, limit or prohibit their use of SBIC debentures, declare outstanding SBIC debentures immediately due and payable, and/or limit them from making new investments.

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In addition, the SBA can revoke or suspend a license for willful or repeated violation of, or willful or repeated failure to observe, any provision of the Small Business Investment Act of 1958 or any rule or regulation promulgated thereunder. Such actions by the SBA would, in turn, negatively affect us.

Because we borrow money, the potential for gain or loss on amounts invested in us is magnified and may increase the risk of investing in us.

Borrowings, also known as leverage, magnify the potential for loss on investments in our indebtedness and gain or loss on investments in our equity capital. As we use leverage to partially finance our investments, you will experience increased risks of investing in our securities. We, through the Funds, issue debt securities guaranteed by the SBA and sold in the capital markets. As a result of its guarantee of the debt securities, the SBA has fixed dollar claims on the assets of the Funds that are superior to the claims of our securities holders. We may also borrow from banks and other lenders, including under our Credit Facility, and may issue debt securities or enter into other types of borrowing arrangements in the future. See "Management's Discussion and Analysis of Financial Condition and Results of Operations — Liquidity and Capital Resources — Capital Resources" for a discussion regarding our outstanding indebtedness. If the value of our assets decreases, leveraging would cause net asset value to decline more sharply than it otherwise would have had we not leveraged our business. Similarly, any decrease in our income would cause net investment income to decline more sharply than it would have had we not leveraged our business. Such a decline could negatively affect our ability to pay common stock dividends, scheduled debt payments or other payments related to our securities. Use of leverage is generally considered a speculative investment technique.

As of December 31, 2018, we, through the Funds, had $345.8 million of outstanding indebtedness guaranteed by the SBA, which had a weighted-average annualized interest cost of approximately 3.7%. The debentures guaranteed by the SBA have a maturity of ten years, with a current weighted-average remaining maturity of 5.6 years as of December 31, 2018, and require semiannual payments of interest. We will need to generate sufficient cash flow to make required interest payments on the debentures. If we are unable to meet the financial obligations under the debentures, the SBA, as a creditor, will have a superior claim to the assets of the Funds over our securities holders in the event we liquidate or the SBA exercises its remedies under such debentures as the result of a default by us.

In addition, as of December 31, 2018, we had $301.0 million outstanding under our Credit Facility. Borrowings under the Credit Facility bear interest, subject to our election, on a per annum basis at a rate equal to the applicable LIBOR rate (2.5% as of December 31, 2018) plus (i) 1.875% (or the applicable base rate (Prime Rate of 5.5% as of December 31, 2018) plus 0.875%), as long as we meet certain agreed upon excess collateral and maximum leverage requirements or (ii) 2.0% (or the applicable base rate plus 1.0%) otherwise. We pay unused commitment fees of 0.25% per annum on the unused lender commitments under the Credit Facility. If we are unable to meet the financial obligations under the Credit Facility, the Credit Facility lending group will have a superior claim to the assets of MSCC and its subsidiaries (excluding the assets of the Funds) over our stockholders in the event we liquidate or the lending group exercises its remedies under the Credit Facility as the result of a default by us.

In April 2013, we issued $92.0 million, including the underwriters' full exercise of their over-allotment option, in aggregate principal amount of the 6.125% Notes (the "6.125% Notes"). The 6.125% Notes bore interest at a rate of 6.125% per year payable quarterly on January 1, April 1, July 1 and October 1 of each year. The total net proceeds to us from the 6.125% Notes, after underwriting discounts and estimated offering expenses payable, were approximately $89.0 million. On April 2, 2018, we redeemed the entire principal amount of the issued and outstanding 6.125% Notes effective April 1, 2018 (the "Redemption Date"). The 6.125% Notes were redeemed at par value, plus the accrued and unpaid interest thereon from January 1, 2018, through, but excluding, the Redemption Date. As part of the redemption, we recognized a realized loss on extinguishment of debt of $1.5 million in the second quarter of 2018 related to the write-off of the related unamortized deferred financing costs.

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In November 2014, we issued $175.0 million in aggregate principal amount of 4.50% unsecured notes due 2019 (the "4.50% Notes due 2019") at an issue price of 99.53%. As of December 31, 2018, the outstanding balance of the 4.50% Notes due 2019 was $175.0 million. The 4.50% Notes due 2019 are unsecured obligations and rank pari passu with our current and future unsecured indebtedness; senior to any of our future indebtedness that expressly provides it is subordinated to the 4.50% Notes due 2019; effectively subordinated to all of our existing and future secured indebtedness, to the extent of the value of the assets securing such indebtedness, including borrowings under our Credit Facility; and structurally subordinated to all existing and future indebtedness and other obligations of any of our subsidiaries, including without limitation, the indebtedness of the Funds. The 4.50% Notes due 2019 mature on December 1, 2019, and may be redeemed in whole or in part at any time at our option subject to certain make-whole provisions.

In November 2017, we issued $185.0 million in aggregate principal amount of 4.50% unsecured notes due 2022 (the "4.50% Notes due 2022," together with the 4.50% Notes due 2019, the "Notes") at an issue price of 99.16%. As of December 31, 2018, the outstanding balance of the 4.50% Notes due 2022 was $185.0 million. The 4.50% Notes due 2022 are unsecured obligations and rank pari passu with our current and future unsecured indebtedness; senior to any of our future indebtedness that expressly provides it is subordinated to the 4.50% Notes due 2022; effectively subordinated to all of our existing and future secured indebtedness, to the extent of the value of the assets securing such indebtedness, including borrowings under our Credit Facility; and structurally subordinated to all existing and future indebtedness and other obligations of any of our subsidiaries, including without limitation, the indebtedness of the Funds. The 4.50% Notes due 2022 mature on December 1, 2022, and may be redeemed in whole or in part at any time at our option subject to certain make-whole provisions.

Illustration. The following table illustrates the effect of leverage on returns from an investment in our common stock assuming various annual returns, net of expenses. The calculations in the table below are hypothetical and actual returns may be higher or lower than those appearing below.

Assumed Return on Our Portfolio(1)
(net of expenses)

Our ability to achieve our investment objective may depend in part on our ability to access additional leverage on favorable terms by issuing debentures guaranteed by the SBA through the Funds, by borrowing from banks or insurance companies or by issuing other debt securities and there can be no assurance that such additional leverage can in fact be achieved.

All of our assets are subject to security interests under our secured Credit Facility or subject to a superior claim over our stockholders by the SBA and if we default on our obligations under the Credit Facility or with respect to our SBA-guaranteed debentures, we may suffer adverse consequences, including foreclosure on our assets.

Substantially all of our assets are currently pledged as collateral under our Credit Facility or are subject to a superior claim over our stockholders by the SBA. If we default on our obligations under the Credit Facility or our SBA-guaranteed debentures, the lenders and/or the SBA may have the right to foreclose upon and sell, or otherwise transfer, the collateral subject to their security interests or their superior claim. In such event, we may be forced to sell our investments to raise funds to repay our outstanding borrowings in order to

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avoid foreclosure and these forced sales may be at times and at prices we would not consider advantageous. Moreover, such deleveraging of our company could significantly impair our ability to effectively operate our business in the manner in which we have historically operated. As a result, we could be forced to curtail or cease new investment activities and lower or eliminate the dividends that we have historically paid to our stockholders. In addition, if the lenders exercise their right to sell the assets pledged under our Credit Facility, such sales may be completed at distressed sale prices, thereby diminishing or potentially eliminating the amount of cash available to us after repayment of the amounts outstanding under the Credit Facility.

Recent legislation may allow us to incur additional leverage.

The 1940 Act generally prohibits us from incurring indebtedness unless immediately after such borrowing we have an asset coverage for total borrowings of at least 200% (i.e., the amount of debt may not exceed 50% of the value of our assets). However, legislation passed in March 2018 has modified the 1940 Act by allowing a BDC to increase the maximum amount of leverage it may incur by lowering the required asset coverage ratio of 200% to an asset coverage ratio of 150% (i.e., the amount of debt may not exceed 66 ² / 3 % of the value of our assets), if certain requirements are met. Under the legislation, we are allowed to increase our leverage capacity if stockholders representing at least a majority of the votes cast, when a quorum is met, approve a proposal to do so. If we receive stockholder approval, we would be allowed to increase our leverage capacity on the first day after such approval. Alternatively, the legislation allows a "required majority" (as defined in Section 57(o) of the 1940 Act) of the members of our board of directors to approve an increase in our leverage capacity, and such approval would become effective after one year from the date of approval. In either case, we would be required to make certain disclosures on our website and in SEC filings regarding, among other things, the receipt of approval to increase our leverage, our leverage capacity and usage, and risks related to leverage. As a result of this legislation, we may be able to increase our leverage up to an amount that reduces our asset coverage ratio from 200% to 150% (i.e., the amount of debt may not exceed 66 ² / 3 % of the value of our assets). See "Risk Factors — Risks Relating to Our Business and Structure — Because we borrow money, the potential for gain or loss on amounts invested in us is magnified and may increase the risk of investing in us" for a discussion of the risks associated with leverage.

Further downgrades of the U.S. credit rating, automatic spending cuts or another government shutdown could negatively impact our liquidity, financial condition and earnings.

Recent U.S. debt ceiling and budget deficit concerns have increased the possibility of additional credit-rating downgrades and economic slowdowns, or a recession in the U.S. Although U.S. lawmakers passed legislation to raise the federal debt ceiling on multiple occasions, ratings agencies have lowered or threatened to lower the long-term sovereign credit rating on the United States. The impact of this or any further downgrades to the U.S. government's sovereign credit rating or its perceived creditworthiness could adversely affect the U.S. and global financial markets and economic conditions. Absent further quantitative easing by the Federal Reserve, these developments could cause interest rates and borrowing costs to rise, which may negatively impact our ability to access the debt markets on favorable terms. In addition, disagreement over the federal budget has caused the U.S. federal government to shut down for periods of time. Continued adverse political and economic conditions could have a material adverse effect on our business, financial condition and results of operations.

The interest rates of our floating-rate loans to our portfolio companies that extend beyond 2021 might be subject to change based on recent regulatory changes

LIBOR is the basic rate of interest used in lending transactions between banks on the London interbank market and is widely used as a reference for setting the interest rate on loans globally. We typically use LIBOR as a reference rate in floating-rate loans we extend to portfolio companies such that the interest due to us pursuant to a term loan extended to a portfolio company is calculated using LIBOR. The terms of our debt investments generally include minimum interest rate floors which are calculated based on LIBOR.

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On July 27, 2017, the United Kingdom's Financial Conduct Authority, which regulates LIBOR, announced that it intends to phase out LIBOR by the end of 2021. It is unclear if at that time whether LIBOR will cease to exist or if new methods of calculating LIBOR will be established such that it continues to exist after 2021. As such, the potential effect of any such event on our net investment income cannot yet be determined. The U.S. Federal Reserve, in conjunction with the Alternative Reference Rates Committee, a steering committee comprised of large U.S. financial institutions, is considering replacing U.S. dollar LIBOR with a new index calculated by short term repurchase agreements, backed by Treasury securities. If LIBOR ceases to exist, we may need to renegotiate the credit agreements extending beyond 2021 with our portfolio companies that utilize LIBOR as a factor in determining the interest rate to replace LIBOR with the new standard that is established. In addition, any further changes or reforms to the determination or supervision of LIBOR may result in a sudden or prolonged increase or decrease in reported LIBOR, which could have an adverse impact on the market value for or value of any LIBOR-linked securities, loans and other financial obligations or extensions of credit held by or due to us and could have a material adverse effect on our business, financial condition and results of operations.

We may experience fluctuations in our operating results.

We could experience fluctuations in our operating results due to a number of factors, including our ability or inability to make investments in companies that meet our investment criteria, the interest rate payable on the debt securities we acquire, the level of portfolio dividend and fee income, the level of our expenses, variations in and the timing of the recognition of realized and unrealized gains or losses, the degree to which we encounter competition in our markets and general economic conditions. As a result of these factors, operating results for any period should not be relied upon as being indicative of performance in future periods.

Our Board of Directors may change our operating policies and strategies without prior notice or stockholder approval, the effects of which may be adverse.

Our Board of Directors has the authority to modify or waive our current operating policies, investment criteria and strategies without prior notice and without stockholder approval. We cannot predict the effect any changes to our current operating policies, investment criteria and strategies would have on our business, net asset value, operating results and value of our stock. However, the effects might be adverse, which could negatively impact our ability to pay interest and principal payments to holders of our debt instruments and dividends to our stockholders and cause our investors to lose all or part of their investment in us.

We will be subject to corporate-level U.S. federal income tax if we are unable to qualify as a RIC under Subchapter M of the Code.

To maintain RIC tax treatment under the Code, we must meet the following annual distribution, income source and asset diversification requirements:

•

The Annual Distribution Requirement for a RIC will be satisfied if we distribute to our stockholders on an annual basis at least 90% of our net ordinary taxable income and realized net short-term capital gains in excess of realized net long-term capital losses, if any. Depending on the level of taxable income earned in a tax year, we may choose to carry forward taxable income in excess of current year distributions into the next tax year and pay a 4% U.S. federal excise tax on such income. Any such carryover taxable income must be distributed through a dividend declared prior to filing the final tax return related to the year which generated such taxable income. For more information regarding tax treatment, see "Business — Regulation — Taxation as a Regulated Investment Company." Because we use debt financing, we are subject to certain asset coverage ratio requirements under the 1940 Act and are (and may in the future become) subject to certain financial covenants under loan and credit agreements that could, under certain circumstances, restrict us from making distributions necessary to satisfy the distribution requirement. In addition, because we receive non-cash sources of income such as PIK interest which involves us recognizing taxable income without receiving the cash representing

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such income, we may have difficulty meeting the distribution requirement. If we are unable to obtain cash from other sources, we could fail to qualify for RIC tax treatment and thus become subject to corporate-level U.S. federal income tax.

•

The source-of-income requirement will be satisfied if we obtain at least 90% of our gross income for each year from distributions, interest, gains from the sale of stock or securities or similar sources.



•

The asset diversification requirement will be satisfied if we meet certain asset diversification requirements at the end of each quarter of our taxable year. To satisfy this requirement, at least 50% of the value of our assets must consist of cash, cash equivalents, U.S. government securities, securities of other RICs, and other acceptable securities; and no more than 25% of the value of our assets can be invested in the securities, other than U.S. government securities or securities of other RICs, (i) of one issuer, (ii) of two or more issuers that are controlled, as determined under applicable Code rules, by us and that are engaged in the same or similar or related trades or businesses or (iii) of certain "qualified publicly traded partnerships."

Failure to meet these requirements may result in our having to dispose of certain investments quickly in order to prevent the loss of RIC status. Because most of our investments are in privately held companies, and therefore illiquid, any such dispositions could be made at disadvantageous prices and could result in substantial losses. Moreover, if we fail to maintain RIC tax treatment for any reason and are subject to corporate income tax, the resulting corporate taxes could substantially reduce our net assets, the amount of income available for distribution and the amount of our distributions.

We may not be able to pay distributions to our stockholders, our distributions may not grow over time, and a portion of distributions paid to our stockholders may be a return of capital, which is a distribution of the stockholders' invested capital.

We intend to pay distributions to our stockholders out of assets legally available for distribution. We cannot assure you that we will achieve investment results that will allow us to pay a specified level of cash distributions, previously projected distributions for future periods, or year-to-year increases in cash distributions. Our ability to pay distributions might be adversely affected by, among other things, the impact of one or more of the risk factors described herein. In addition, the inability to satisfy the asset coverage test applicable to us as a BDC could limit our ability to pay distributions. All distributions will be paid at the discretion of our Board of Directors and will depend on our earnings, our financial condition, maintenance of our RIC status, compliance with applicable BDC regulations, compliance with our debt covenants, each of the Funds' compliance with applicable SBIC regulations and such other factors as our Board of Directors may deem relevant from time to time. We cannot assure you that we will pay distributions to our stockholders in the future.

When we make distributions, we will be required to determine the extent to which such distributions are paid out of current or accumulated taxable earnings, recognized capital gains or capital. To the extent there is a return of capital, investors will be required to reduce their basis in our stock for U.S. federal income tax purposes, which may result in higher tax liability when the shares are sold, even if they have not increased in value or have lost value. In addition, any return of capital will be net of any sales load and offering expenses associated with sales of shares of our common stock. In the future, our distributions may include a return of capital.

We may have difficulty paying the distributions required to maintain RIC tax treatment under the Code if we recognize income before or without receiving cash representing such income.

We will include in income certain amounts that we have not yet received in cash, such as: (i) amortization of original issue discount, which may arise if we receive warrants in connection with the origination of a loan such that ascribing a value to the warrants creates original issue discount in the debt instrument, if we invest in a debt investment at a discount to the par value of the debt security or possibly in other circumstances; (ii) contractual payment-in-kind, or PIK, interest, which represents contractual interest

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added to the loan balance and due at the end of the loan term; (iii) contractual preferred dividends, which represents contractual dividends added to the preferred stock and due at the end of the preferred stock term, subject to adequate profitability at the portfolio company; or (iv) amortization of market discount, which is associated with loans purchased in the secondary market at a discount to par value. Such amortization of original issue discounts, increases in loan balances as a result of contractual PIK arrangements, cumulative preferred dividends, or amortization of market discount will be included in income before we receive the corresponding cash payments. We also may be required to include in income certain other amounts before we receive such amounts in cash. Investments structured with these features may represent a higher level of credit risk compared to investments generating income which must be paid in cash on a current basis. For the year ended December 31, 2018, (i) approximately 1.0% of our total investment income was attributable to PIK income not paid currently in cash, (ii) approximately 0.5% of our total investment income was attributable to amortization of original issue discount, (iii) approximately 1.0% of our total investment income was attributable to cumulative dividend income not paid currently in cash, and (iv) approximately 2.5% of our total investment income was attributable to amortization of market discount on loans purchased in the secondary market at a discount.

Since, in certain cases, we may recognize taxable income before or without receiving cash representing such income, we may have difficulty meeting the Annual Distribution Requirement necessary to maintain RIC tax treatment under the Code. Accordingly, we may have to sell some of our investments at times and/or at prices we would not consider advantageous, raise additional debt or equity capital or forgo new investment opportunities for this purpose. If we are not able to obtain cash from other sources, we may fail to qualify for RIC tax treatment and thus become subject to corporate-level U.S. federal income tax. For additional discussion regarding the tax implications of a RIC, please see "Business — Regulation — Taxation as a Regulated Investment Company."

We may in the future choose to pay dividends in our own stock, in which case you may be required to pay tax in excess of the cash you receive.

We may distribute taxable dividends that are payable in part in our stock. Under certain applicable provisions of the Code and the Treasury regulations, distributions payable by us in cash or in shares of stock (at the stockholders election) would satisfy the Annual Distribution Requirement. The Internal Revenue Service has issued guidance providing that a dividend payable in stock or in cash at the election of the stockholders will be treated as a taxable dividend eligible for the dividends paid deduction provided that at least 20% of the total dividend is payable in cash and certain other requirements are satisfied. Taxable stockholders receiving such dividends will be required to include the full amount of the dividend as ordinary income (or as long-term capital gain to the extent such dividend is properly reported as a capital gain dividend) to the extent of our current and accumulated earnings and profits for U.S. federal income tax purposes. As a result, a U.S. stockholder may be required to pay tax with respect to such dividends in excess of any cash received. If a U.S. stockholder sells the stock it receives as a dividend in order to pay this tax, the sales proceeds may be less than the amount included in income with respect to the dividend, depending on the market price of our stock at the time of the sale. Furthermore, with respect to non-U.S. stockholders, we may be required to withhold U.S. tax with respect to such dividends, including in respect of all or a portion of such dividend that is payable in stock. In addition, if a significant number of our stockholders determine to sell shares of our stock in order to pay taxes owed on dividends, it may put downward pressure on the trading price of our stock.

Each of the Funds, as an SBIC, may be unable to make distributions to us that will enable us to meet or maintain RIC status, which could result in the imposition of an entity-level tax.

In order for us to continue to qualify for RIC tax treatment and to minimize corporate-level U.S. federal taxes, we will be required to distribute substantially all of our net ordinary taxable income and net capital gain income, including taxable income from certain of our subsidiaries, which includes the income from the Funds. We will be partially dependent on the Funds for cash distributions to enable us to meet the RIC

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distribution requirements. The Funds may be limited by SBIC regulations from making certain distributions to us that may be necessary to enable us to maintain our status as a RIC. We may have to request a waiver of the SBA's restrictions for the Funds to make certain distributions to maintain our eligibility for RIC status. We cannot assure you that the SBA will grant such waiver and if the Funds are unable to obtain a waiver, compliance with the SBIC regulations may result in loss of RIC tax treatment and a consequent imposition of an entity-level tax on us.

Because we intend to distribute substantially all of our taxable income to our stockholders to maintain our status as a RIC, we will continue to need additional capital to finance our growth, and regulations governing our operation as a BDC will affect our ability to, and the way in which we, raise additional capital and make distributions.

In order to satisfy the requirements applicable to a RIC and to minimize corporate-level U.S. federal taxes, we intend to distribute to our stockholders substantially all of our net ordinary taxable income and net capital gain income. We may carry forward excess undistributed taxable income into the next year, net of the 4% U.S. federal excise tax. Any such carryover taxable income must be distributed through a dividend declared prior to filing the final tax return related to the year which generated such taxable income. As a BDC, we generally are required to meet an asset coverage ratio, as defined in the 1940 Act, of at least 200% (or 150% if certain requirements are met) immediately after each issuance of senior securities. This requirement limits the amount that we may borrow and may prohibit us from making distributions. Because we will continue to need capital to grow our Investment Portfolio, this limitation may prevent us from incurring debt and require us to raise additional equity at a time when it may be disadvantageous to do so.

While we expect to be able to borrow and to issue additional debt and equity securities, we cannot assure you that debt and equity financing will be available to us on favorable terms, or at all. In addition, as a BDC, we generally are not permitted to issue equity securities priced below net asset value without stockholder approval. If additional funds are not available to us, we could be forced to curtail or cease new investment activities, and our net asset value could decline.

Stockholders may incur dilution if we sell shares of our common stock in one or more offerings at prices below the then current net asset value per share of our common stock or issue securities to subscribe to, convert to or purchase shares of our common stock.

The 1940 Act prohibits us from selling shares of our common stock at a price below the current net asset value per share of such stock, with certain exceptions. One such exception is prior stockholder approval of issuances below net asset value provided that our Board of Directors makes certain determinations. We did not seek stockholder authorization to sell shares of our common stock below the then current net asset value per share of our common stock at our 2018 annual meeting of stockholders because our common stock price per share had been trading significantly above the net asset value per share of our common stock. We may, however, seek such authorization at future annual or special meetings of stockholders. Our stockholders have previously approved a proposal to authorize us to issue securities to subscribe to, convert to, or purchase shares of our common stock in one or more offerings. Any decision to sell shares of our common stock below the then current net asset value per share of our common stock or securities to subscribe to, convert to, or purchase shares of our common stock would be subject to the determination by our Board of Directors that such issuance is in our and our stockholders' best interests.

If we were to sell shares of our common stock below net asset value per share, such sales would result in an immediate dilution to the net asset value per share. This dilution would occur as a result of the sale of shares at a price below the then current net asset value per share of our common stock and a proportionately greater decrease in a stockholder's interest in our earnings and assets and voting interest in us than the increase in our assets resulting from such issuance. In addition, if we issue securities to subscribe to, convert to or purchase shares of common stock, the exercise or conversion of such securities would increase the number of outstanding shares of our common stock. Any such exercise would be dilutive on the voting power

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of existing stockholders, and could be dilutive with regard to dividends and our net asset value, and other economic aspects of the common stock.

Because the number of shares of common stock that could be so issued and the timing of any issuance is not currently known, the actual dilutive effect cannot be predicted; however, the example below illustrates the effect of dilution to existing stockholders resulting from the sale of common stock at prices below the net asset value of such shares.

Illustration: Example of Dilutive Effect of the Issuance of Shares Below Net Asset Value. Assume that Company XYZ has 1,000,000 total shares outstanding, $15,000,000 in total assets and $5,000,000 in total liabilities. The net asset value per share of the common stock of Company XYZ is $10.00. The following table illustrates the reduction to net asset value, or NAV, and the dilution experienced by Stockholder A following the sale of 40,000 shares of the common stock of Company XYZ at $9.50 per share, a price below its NAV per share.

Changes in laws or regulations governing our operations may adversely affect our business or cause us to alter our business strategy.

We, the Funds, and our portfolio companies are subject to applicable local, state and federal laws and regulations. New legislation may be enacted or new interpretations, rulings or regulations could be adopted, including those governing the types of investments we are permitted to make, any of which could harm us and our stockholders, potentially with retroactive effect. In addition, any change to the SBA's current debenture SBIC program could have a significant impact on our ability to obtain lower-cost leverage through the Funds, and therefore, our ability to compete with other finance companies.

Additionally, any changes to the laws and regulations governing our operations relating to permitted investments may cause us to alter our investment strategy in order to avail ourselves of new or different opportunities. Such changes could result in material differences to the strategies and plans set forth herein and may result in our investment focus shifting from the areas of expertise of our investment team to other types of investments in which our investment team may have less expertise or little or no experience. Thus, any such changes, if they occur, could have a material adverse effect on our results of operations and the value of your investment.

The Tax Cuts and Jobs Act could have a negative effect on us, our subsidiaries, our portfolio companies and the holders of our securities.

On December 20, 2017, the U.S. House of Representatives and the U.S. Senate each voted to approve H.R. 1 (the "Tax Cuts and Jobs Act") and, on December 22, 2017, President Trump signed the Tax Cuts and Jobs Act into law. The Tax Cuts and Jobs Act made significant changes to the U.S. federal income tax rules applicable to both individuals and entities, including corporations. The Tax Cuts and Jobs Act includes provisions that, among other things, reduce the U.S. corporate tax rate, introduce a capital investment deduction, limit the interest deduction, limit the use of net operating losses to offset future taxable income

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and make extensive changes to the U.S. international tax system. Treasury and the Internal Revenue Service continue to release guidance in the form of regulations providing rules for implementation and interpretation of the Tax Cuts and Jobs Act provisions. Uncertainty remains regarding significant provisions of the Tax Cuts and Jobs Act while some of the Treasury regulations and guidance remain in proposed form. Accordingly, we cannot predict any additional future impact the enactment of such legislation will have on us, our subsidiaries, our portfolio companies and the holders of our securities.

Terrorist attacks, acts of war or natural disasters may affect any market for our securities, impact the businesses in which we invest and harm our business, operating results and financial condition.

Terrorist acts, acts of war or natural disasters may disrupt our operations, as well as the operations of the businesses in which we invest. Such acts have created, and continue to create, economic and political uncertainties and have contributed to global economic instability. Future terrorist activities, military or security operations, or natural disasters could further weaken the domestic/global economies and create additional uncertainties, which may negatively impact the businesses in which we invest directly or indirectly and, in turn, could have a material adverse impact on our business, operating results and financial condition. Losses from terrorist attacks and natural disasters are generally uninsurable.

We are highly dependent on information systems and systems failures could significantly disrupt our business, which may, in turn, negatively affect the market price of our common stock and our ability to pay dividends.

Our business is highly dependent on our and third parties' communications and information systems. Any failure or interruption of those systems, including as a result of the termination of an agreement with any third-party service providers, could cause delays or other problems in our activities. Our financial, accounting, data processing, backup or other operating systems and facilities may fail to operate properly or become disabled or damaged as a result of a number of factors including events that are wholly or partially beyond our control and adversely affect our business. There could be:

•

sudden electrical or telecommunications outages;



•

natural disasters such as earthquakes, tornadoes and hurricanes;



•

events arising from local or larger scale political or social matters, including terrorist acts; and



•

cyber attacks.

The failure in cyber security systems, as well as the occurrence of events unanticipated in our disaster recovery systems and management continuity planning could impair our ability to conduct business effectively.

The occurrence of a disaster such as a cyber-attack, a natural catastrophe, an industrial accident, a terrorist attack or war, events unanticipated in our disaster recovery systems, or a support failure from external providers, could have an adverse effect on our ability to conduct business and on our results of operations and financial condition, particularly if those events affect our computer-based data processing, transmission, storage, and retrieval systems or destroy data. If a significant number of our managers were unavailable in the event of a disaster, our ability to effectively conduct our business could be severely compromised.

We depend heavily upon computer systems to perform necessary business functions. Despite our implementation of a variety of security measures, our computer systems could be subject to cyber-attacks and unauthorized access, such as physical and electronic break-ins or unauthorized tampering. Like other companies, we may experience threats to our data and systems, including malware and computer virus attacks, unauthorized access, system failures and disruptions. If one or more of these events occurs, it could potentially jeopardize the confidential, proprietary and other information processed and stored in, and transmitted through, our computer systems and networks, or otherwise cause interruptions or malfunctions in

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our operations, which could result in damage to our reputation, financial losses, litigation, increased costs, regulatory penalties and/or customer dissatisfaction or loss.

RISKS RELATED TO OUR INVESTMENTS

Our investments in portfolio companies involve higher levels of risk, and we could lose all or part of our investment.

Investing in our portfolio companies exposes us indirectly to a number of significant risks. Among other things, these companies:

•

may have limited financial resources and may be unable to meet their obligations under their debt instruments that we hold, which may be accompanied by a deterioration in the value of any collateral and a reduction in the likelihood of us realizing any guarantees from subsidiaries or affiliates of our portfolio companies that we may have obtained in connection with our investment, as well as a corresponding decrease in the value of the equity components of our investments;



•

may have shorter operating histories, narrower product lines, smaller market shares and/or significant customer concentrations than larger businesses, which tend to render them more vulnerable to competitors' actions and market conditions, as well as general economic downturns;



•

are more likely to depend on the management talents and efforts of a small group of persons; therefore, the death, disability, resignation, termination or significant under-performance of one or more of these persons could have a material adverse impact on our portfolio company and, in turn, on us;



•

generally have less predictable operating results, may from time to time be parties to litigation, may be engaged in rapidly changing businesses with products subject to a substantial risk of obsolescence, and may require substantial additional capital to support their operations, finance expansion or maintain their competitive position; and



•

generally have less publicly available information about their businesses, operations and financial condition. We are required to rely on the ability of our management team and investment professionals to obtain adequate information to evaluate the potential returns from investing in these companies. If we are unable to uncover all material information about these companies, we may not make a fully informed investment decision, and may lose all or part of our investment.

In addition, in the course of providing significant managerial assistance to certain of our portfolio companies, certain of our officers and directors may serve as directors on the boards of such companies. To the extent that litigation arises out of our investments in these companies, our officers and directors may be named as defendants in such litigation, which could result in an expenditure of funds (through our indemnification of such officers and directors) and the diversion of management time and resources.

A decline in oil and natural gas prices could have a material adverse effect on us.

A decline in oil and natural gas prices could adversely affect (i) the credit quality of our debt investments and (ii) the underlying operating performance of our equity investments in energy-related businesses and in portfolio companies located in geographic areas which are more sensitive to the health of the oil and gas industries. A decrease in credit quality and the operating performance would, in turn, negatively affect the fair value of these investments, which would consequently negatively affect our net asset value. Should a decline in oil and natural gas prices persist for an extended period of time, it is likely that the ability of these investments to satisfy financial or operating covenants imposed by us or other lenders will be adversely affected, thereby negatively impacting their financial condition and their ability to satisfy their debt service and other obligations to us. Likewise, should a decline in oil and natural gas prices persist, it is likely that our energy-related portfolio companies' and other affected companies' cash flow and profit generating

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capacities would also be adversely affected thereby negatively impacting their ability to pay us dividends or distributions on our equity investments.

We may be exposed to higher risks with respect to our investments that include original issue discount or PIK interest.

Our investments may include original issue discount and contractual PIK interest, which represents contractual interest added to a loan balance and due at the end of such loan's term. To the extent original issue discount or PIK interest constitute a portion of our income, we are exposed to typical risks associated with such income being required to be included in taxable and accounting income prior to receipt of cash, including the following:

•

original issue discount and PIK instruments may have higher yields, which reflect the payment deferral and credit risk associated with these instruments;



•

for accounting purposes, cash distributions to investors representing original issue discount income are not derived from paid in capital, although they may be effectively paid from any offering proceeds during any given period; thus, although the source for the cash used to pay a distribution of original issue discount income may come from the cash invested by investors, the 1940 Act does not require that investors be given notice of this fact;



•

original issue discount and PIK instruments may have unreliable valuations because their continuing accruals require continuing judgments about the collectability of the deferred payments and the value of the collateral; and



•

original issue discount and PIK instruments may represent a higher credit risk than coupon loans; even if the conditions for income accrual under generally accepted accounting principles in the United States of America are satisfied, a borrower could still default when actual payment is due upon the maturity of such loan.

The lack of liquidity in our investments may adversely affect our business.

We invest in companies whose securities are not publicly traded, and whose securities will be subject to legal and other restrictions on resale or will otherwise be less liquid than publicly traded securities. The illiquidity of these investments may make it difficult for us to sell these investments when desired. In addition, if we are required to liquidate all or a portion of our portfolio quickly, we may realize significantly less than the value at which we had previously recorded these investments. As a result, we do not expect to achieve liquidity in our investments in the near-term. Our investments are usually subject to contractual or legal restrictions on resale or are otherwise illiquid because there is usually no established trading market for such investments. The illiquidity of most of our investments may make it difficult for us to dispose of them at a favorable price, and, as a result, we may suffer losses.

We may not have the funds or ability to make additional investments in our portfolio companies.

We may not have the funds or ability to make additional investments in our portfolio companies. After our initial investment in a portfolio company, we may be called upon from time to time to provide additional funds to such company or have the opportunity to increase our investment through the extension of additional loans, the exercise of a warrant to purchase equity securities, or the funding of additional equity investments. There is no assurance that we will make, or will have sufficient funds to make, follow-on investments. Any decisions not to make a follow-on investment or any inability on our part to make such an investment may have a negative impact on a portfolio company in need of such an investment, may result in a missed opportunity for us to increase our participation in a successful operation, may reduce our ability to protect an existing investment or may reduce the expected yield on the investment.

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Our portfolio companies may incur debt that ranks equally with, or senior to, our investments in such companies.

We invest primarily in the secured term debt of LMM, Private Loan and Middle Market companies and equity issued by LMM companies. Our portfolio companies may have, or may be permitted to incur, other debt that ranks equally with, or senior to, the debt in which we invest. By their terms, such debt instruments may entitle the holders to receive payment of interest or principal on or before the dates on which we are entitled to receive payments with respect to the debt instruments in which we invest. Also, in the event of insolvency, liquidation, dissolution, reorganization or bankruptcy of a portfolio company, holders of debt instruments ranking senior to our investment in that portfolio company would typically be entitled to receive payment in full before we receive any distribution. After repaying such senior creditors, such portfolio company may not have any remaining assets to use for repaying its obligation to us. In the case of debt ranking equally with debt instruments in which we invest, we would have to share on an equal basis any distributions with other creditors holding such debt in the event of an insolvency, liquidation, dissolution, reorganization or bankruptcy of the relevant portfolio company.

There may be circumstances where our debt investments could be subordinated to claims of other creditors or we could be subject to lender liability claims.

Even though we may have structured certain of our investments as secured loans, if one of our portfolio companies were to go bankrupt, depending on the facts and circumstances, and based upon principles of equitable subordination as defined by existing case law, a bankruptcy court could subordinate all or a portion of our claim to that of other creditors and transfer any lien securing such subordinated claim to the bankruptcy estate. The principles of equitable subordination defined by case law have generally indicated that a claim may be subordinated only if its holder is guilty of misconduct or where the senior loan is re-characterized as an equity investment and the senior lender has actually provided significant managerial assistance to the bankrupt debtor. We may also be subject to lender liability claims for actions taken by us with respect to a borrower's business or instances where we exercise control over the borrower. It is possible that we could become subject to a lender liability claim, including as a result of actions taken in rendering significant managerial assistance or actions to compel and collect payments from the borrower outside the ordinary course of business.

Second priority liens on collateral securing loans that we make to our portfolio companies may be subject to control by senior creditors with first priority liens. If there is a default, the value of the collateral may not be sufficient to repay in full both the first priority creditors and us.

Certain loans that we make are secured by a second priority security interest in the same collateral pledged by a portfolio company to secure senior debt owed by the portfolio company to commercial banks or other traditional lenders. Often the senior lender has procured covenants from the portfolio company prohibiting the incurrence of additional secured debt without the senior lender's consent. Prior to and as a condition of permitting the portfolio company to borrow money from us secured by the same collateral pledged to the senior lender, the senior lender will require assurances that it will control the disposition of any collateral in the event of bankruptcy or other default. In many such cases, the senior lender will require us to enter into an "intercreditor agreement" prior to permitting the portfolio company to borrow from us. Typically the intercreditor agreements we are requested to execute expressly subordinate our debt instruments to those held by the senior lender and further provide that the senior lender shall control: (1) the commencement of foreclosure or other proceedings to liquidate and collect on the collateral; (2) the nature, timing and conduct of foreclosure or other collection proceedings; (3) the amendment of any collateral document; (4) the release of the security interests in respect of any collateral; and (5) the waiver of defaults under any security agreement. Because of the control we may cede to senior lenders under intercreditor agreements we may enter, we may be unable to realize the proceeds of any collateral securing some of our loans.

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Finally, the value of the collateral securing our debt investment will ultimately depend on market and economic conditions, the availability of buyers and other factors. Therefore, there can be no assurance that the proceeds, if any, from the sale or sales of all of the collateral would be sufficient to satisfy the loan obligations secured by our first or second priority liens. There is also a risk that such collateral securing our investments will decrease in value over time, will be difficult to sell in a timely manner, will be difficult to appraise and will fluctuate in value based upon the success of the portfolio company and market conditions. If such proceeds are not sufficient to repay amounts outstanding under the loan obligations secured by our second priority liens, then we, to the extent not repaid from the proceeds of the sale of the collateral, will only have an unsecured claim against the company's remaining assets, if any.

We are a non-diversified investment company within the meaning of the 1940 Act, and therefore we are not limited with respect to the proportion of our assets that may be invested in securities of a single issuer.

We are classified as a non-diversified investment company within the meaning of the 1940 Act, which means that we are not limited by the 1940 Act with respect to the proportion of our assets that we may invest in securities of a single issuer. To the extent that we assume large positions in the securities of a small number of issuers, our net asset value may fluctuate to a greater extent than that of a diversified investment company as a result of changes in the financial condition or the market's assessment of the issuer. We may also be more susceptible to any single economic or regulatory occurrence than a diversified investment company. Beyond our RIC asset diversification requirements, we do not have fixed guidelines for diversification, and our investments could be concentrated in relatively few portfolio companies. See "Risk Factors — Risks Relating to Our Business and Structure — We will be subject to corporate-level U.S. federal income tax if we are unable to qualify as a RIC under Subchapter M of the Code."

We generally will not control our portfolio companies.

We do not, and do not expect to, control the decision making in many of our portfolio companies, even though we may have board representation or board observation rights, and our debt agreements may contain certain restrictive covenants. As a result, we are subject to the risk that a portfolio company in which we invest will make business decisions with which we disagree and the management of such company will take risks or otherwise act in ways that do not serve our interests as debt investors or minority equity holders. Due to the lack of liquidity for our investments in non-traded companies, we may not be able to dispose of our interests in our portfolio companies as readily as we would like or at an appropriate valuation. As a result, a portfolio company may make decisions that would decrease the value of our portfolio holdings.

Defaults by our portfolio companies will harm our operating results.

A portfolio company's failure to satisfy financial or operating covenants imposed by us or other lenders could lead to non-payment of interest and other defaults and, potentially, termination of its loans and foreclosure on its secured assets, which could trigger cross-defaults under other agreements and jeopardize a portfolio company's ability to meet its obligations under the debt or equity securities that we hold. We may incur expenses to the extent necessary to seek recovery upon default or to negotiate new terms, which may include the waiver of certain financial covenants, with a defaulting portfolio company.

Any unrealized depreciation we experience in our portfolio may be an indication of future realized losses, which could reduce our income and gains available for distribution.

As a BDC, we are required to carry our investments at market value or, if no market value is ascertainable, at the fair value as determined in good faith by our Board of Directors. Decreases in the market values or fair values of our investments will be recorded as unrealized depreciation. Any unrealized depreciation in our portfolio could be an indication of a portfolio company's inability to meet its repayment obligations to us with respect to affected loans or a potential impairment of the value of affected equity investments. This could result in realized losses in the future and ultimately in reductions of our income and gains available for distribution in future periods.

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Prepayments of our debt investments by our portfolio companies could adversely impact our results of operations and reduce our return on equity.

We are subject to the risk that the investments we make in our portfolio companies may be repaid prior to maturity. When this occurs, we will generally reinvest these proceeds in temporary investments, pending their future investment in new portfolio companies. These temporary investments will typically have substantially lower yields than the debt being prepaid and we could experience significant delays in reinvesting these amounts. Any future investment in a new portfolio company may also be at lower yields than the debt that was repaid. As a result, our results of operations could be materially adversely affected if one or more of our portfolio companies elect to prepay amounts owed to us. Additionally, prepayments could negatively impact our return on equity, which could result in a decline in the market price of our securities.

Changes in interest rates may affect our cost of capital, net investment income and value of our investments.

Some of our debt investments will bear interest at variable rates and may be negatively affected by changes in market interest rates. An increase in market interest rates would increase the interest costs and reduce the cash flows of our portfolio companies that have variable rate debt instruments, a situation which could reduce the value of the investment. The value of our investments could also be reduced from an increase in market interest rates as rates available to investors could make an investment in our securities less attractive than alternative investments. In addition, an increase in interest rates would make it more expensive for us to use debt to finance our investments. As a result, a significant increase in market interest rates could increase our cost of capital, which would reduce our net investment income. Conversely, decreases in market interest rates could negatively impact the interest income from our variable rate debt investments. A decrease in market interest rates may also have an adverse impact on our returns by requiring us to accept lower yields on our debt investments and by increasing the risk that our portfolio companies will prepay our debt investments, resulting in the need to redeploy capital at potentially lower rates. See further discussion and analysis at "Item 7A. Quantitative and Qualitative Disclosures about Market Risk".

We may not realize gains from our equity investments.

Certain investments that we have made in the past and may make in the future include warrants or other equity securities. Investments in equity securities involve a number of significant risks, including the risk of further dilution as a result of additional issuances, inability to access additional capital and failure to pay current distributions. Investments in preferred securities involve special risks, such as the risk of deferred distributions, credit risk, illiquidity and limited voting rights. In addition, we may from time to time make non-control, equity investments in portfolio companies. Our goal is ultimately to realize gains upon our disposition of such equity interests. However, the equity interests we receive may not appreciate in value and, in fact, may decline in value. Accordingly, we may not be able to realize gains from our equity interests, and any gains that we do realize on the disposition of any equity interests may not be sufficient to offset any other losses we experience. We also may be unable to realize any value if a portfolio company does not have a liquidity event, such as a sale of the business, recapitalization or public offering, which would allow us to sell the underlying equity interests. We often seek puts or similar rights to give us the right to sell our equity securities back to the portfolio company issuer; however, we may be unable to exercise these put rights for the consideration provided in our investment documents if the issuer is in financial distress.

Our investments in foreign securities may involve significant risks in addition to the risks inherent in U.S. investments.

Our investment strategy contemplates potential investments in debt securities of foreign companies. Investing in foreign companies may expose us to additional risks not typically associated with investing in securities of U.S. companies. These risks include changes in exchange control regulations, political and social instability, expropriation, imposition of foreign taxes, less liquid markets and less available information than is generally the case in the U.S., higher transaction costs, less government supervision of exchanges, brokers and

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issuers, less developed bankruptcy laws, difficulty in enforcing contractual obligations, lack of uniform accounting and auditing standards and greater price volatility.

Although most of our investments will be U.S. dollar denominated, any investments denominated in a foreign currency will be subject to the risk that the value of a particular currency will change in relation to one or more other currencies. Among the factors that may affect currency values are trade balances, the level of short-term interest rates, differences in relative values of similar assets in different currencies, long-term opportunities for investment and capital appreciation, and political developments.

RISKS RELATING TO OUR SECURITIES

Shares of closed-end investment companies, including BDCs, may trade at a discount to their net asset value.

Shares of closed-end investment companies, including BDCs, may trade at a discount to net asset value. This characteristic of closed-end investment companies and BDCs is separate and distinct from the risk that our net asset value per share may decline. We cannot predict whether our common stock will trade at, above or below net asset value. In addition, if our common stock trades below our net asset value per share, we will generally not be able to issue additional common stock at the market price unless our stockholders approve such a sale and our Board of Directors makes certain determinations. See "Risk Factors — Risks Relating to Our Business and Structure — Stockholders may incur dilution if we sell shares of our common stock in one or more offerings at prices below the then current net asset value per share of our common stock or issue securities to subscribe to, convert to or purchase shares of our common stock" for a discussion related to us issuing shares of our common stock below net asset value.

We may be unable to invest a significant portion of the net proceeds from an offering or from exiting an investment or other capital on acceptable terms, which could harm our financial condition and operating results.

Delays in investing the net proceeds raised in an offering or other capital raised or proceeds resulting from exiting an investment may cause our performance to be worse than that of other fully invested BDCs or other lenders or investors pursuing comparable investment strategies. We cannot assure you that we will be able to identify any investments that meet our investment objective or that any investment that we make will produce a positive return. We may be unable to invest the net proceeds of any offering or other capital raised or proceeds resulting from exiting an investment on acceptable terms within the time period that we anticipate or at all, which could harm our financial condition and operating results.

We anticipate that, depending on market conditions and the amount of the capital, it may take us a substantial period of time to invest substantially all the capital in securities meeting our investment objective. During this period, we may invest the capital primarily in marketable securities and idle funds investments, which generally consist of debt investments, independently rated debt investments, certificates of deposit with financial institutions, diversified bond funds and publicly traded debt and equity investments and may produce returns that are significantly lower than the returns which we expect to achieve when our portfolio is fully invested in securities meeting our investment objective. Most of the debt investments that meet our investment criteria are, or would be if rated, below investment grade quality. Indebtedness of below investment grade quality, which is often referred to as "junk," is regarded as having predominantly speculative characteristics with respect to the issuer's capacity to pay interest and repay principal. As a result, any distributions that we pay during such period may be substantially lower than the distributions that we may be able to pay when our portfolio is fully invested in securities meeting our investment objective. In addition, until such time as the net proceeds of any offering or from exiting an investment or other capital are invested in new securities meeting our investment objective, the market price for our securities may decline. Thus, the initial return on your investment may be lower than when, if ever, our portfolio is fully invested in securities meeting our investment objective.

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Investing in our securities may involve a high degree of risk.

The investments we make in accordance with our investment objective may result in a higher amount of risk than alternative investment options and a higher risk of volatility or loss of principal. Our investments in portfolio companies involve higher levels of risk, and therefore, an investment in our securities may not be suitable for someone with lower risk tolerance.

The market price of our securities may be volatile and fluctuate significantly.

Fluctuations in the trading prices of our securities may adversely affect the liquidity of the trading market for our securities and, if we seek to raise capital through future securities offerings, our ability to raise such capital. The market price and liquidity of the market for our securities may be significantly affected by numerous factors, some of which are beyond our control and may not be directly related to our operating performance. These factors include:

•

significant volatility in the market price and trading volume of securities of BDCs or other companies in our sector, which are not necessarily related to the operating performance of these companies;



•

changes in regulatory policies, accounting pronouncements or tax guidelines, particularly with respect to RICs, BDCs or SBICs;



•

the exclusion of BDC common stock from certain market indices, such as what happened with respect to the Russell indices and the Standard and Poor's indices, could reduce the ability of certain investment funds to own our common stock and limit the number of owners of our common stock and otherwise negatively impact the market price of our common stock;



•

inability to obtain any exemptive relief that may be required by us in the future from the SEC;



•

loss of our BDC or RIC status or any of the Funds' status as an SBIC;



•

changes in our earnings or variations in our operating results;



•

changes in the value of our portfolio of investments;



•

any shortfall in our investment income or net investment income or any increase in losses from levels expected by investors or securities analysts;



•

loss of a major funding source;



•

fluctuations in interest rates;



•

the operating performance of companies comparable to us;



•

departure of our key personnel;



•

proposed, or completed, offerings of our securities, including classes other than our common stock;



•

global or national credit market changes; and



•

general economic trends and other external factors.

Provisions of the Maryland General Corporation Law and our articles of incorporation and bylaws could deter takeover attempts and have an adverse impact on the price of our common stock.

The Maryland General Corporation Law and our articles of incorporation and bylaws contain provisions that may have the effect of discouraging, delaying or making difficult a change in control of our company or the removal of our incumbent directors. The existence of these provisions, among others, may have a negative impact on the price of our common stock and may discourage third-party bids for ownership of our company. These provisions may prevent any premiums being offered to you for our common stock.

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The Notes are unsecured and therefore effectively subordinated to any current or future secured indebtedness, including indebtedness under the Credit Facility.

The Notes are not secured by any of our assets or any of the assets of our subsidiaries and rank equally in right of payment with all of our existing and future unsubordinated, unsecured indebtedness. As a result, the Notes are effectively subordinated to any secured indebtedness we or our subsidiaries have currently incurred and may incur in the future (or any indebtedness that is initially unsecured to which we subsequently grant security) to the extent of the value of the assets securing such indebtedness. In any liquidation, dissolution, bankruptcy or other similar proceeding, the holders of any of our existing or future secured indebtedness and the secured indebtedness of our subsidiaries may assert rights against the assets pledged to secure that indebtedness in order to receive full payment of their indebtedness before the assets may be used to pay other creditors, including the holders of the Notes. As of December 31, 2018, we had $301.0 million outstanding under the Credit Facility out of $705.0 million in commitments. The indebtedness under the Credit Facility is senior to the Notes to the extent of the value of the assets securing such indebtedness.

The Notes are structurally subordinated to the indebtedness and other liabilities of our subsidiaries.

The Notes are obligations exclusively of Main Street Capital Corporation and not of any of our subsidiaries. None of our subsidiaries is a guarantor of the Notes, and the Notes are not required to be guaranteed by any subsidiaries we may acquire or create in the future. In addition, several of our subsidiaries, specifically the Funds, maintain significant indebtedness and as a result the Notes are structurally subordinated to the indebtedness of these subsidiaries. For example, as of December 31, 2018, the Funds had collectively issued $345.8 million of the current regulatory maximum of $350.0 million of SBA-guaranteed debentures, which are included in our consolidated financial statements. The assets of such subsidiaries are not directly available to satisfy the claims of our creditors, including holders of the Notes. See "Management's Discussion and Analysis of Financial Condition and Results of Operations — Liquidity and Capital Resources" for more detail on the SBA-guaranteed debentures.

Except to the extent we are a creditor with recognized claims against our subsidiaries, all claims of other creditors of our subsidiaries have priority over our equity interests in such subsidiaries (and therefore the claims of our creditors, including holders of the Notes) with respect to the assets of such subsidiaries. Even if we are recognized as a creditor of one or more of our subsidiaries, our claims would still be effectively subordinated to any security interests in the assets of any such subsidiary and to any indebtedness or other liabilities of any such subsidiary senior to our claims. Consequently, the Notes are structurally subordinated to all indebtedness, including the SBA-guaranteed debentures, and other liabilities of any of our subsidiaries and any subsidiaries that we may in the future acquire or establish. In addition, our subsidiaries may incur substantial additional indebtedness in the future, all of which would be structurally senior to the Notes.

The Notes may or may not have an established trading market. If a trading market in the Notes is developed, it may not be maintained.

The Notes may or may not have an established trading market. If a trading market in the Notes is developed, it may not be maintained. If the Notes are traded, they may trade at a discount to their initial offering price depending on prevailing interest rates, the market for similar securities, our credit ratings, our financial condition or other relevant factors. Accordingly, we cannot assure you that a liquid trading market has been or will develop for the Notes, that you will be able to sell your Notes at a particular time or that the price you receive when you sell will be favorable. To the extent an active trading market does not develop or is not maintained, the liquidity and trading price for the Notes may be harmed. Accordingly, you may be required to bear the financial risk of an investment in the Notes for an indefinite period of time.

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A downgrade, suspension or withdrawal of the credit rating assigned by a rating agency to us or the Notes, if any, or change in the debt markets could cause the liquidity or market value of the Notes to decline significantly.

Our credit ratings are an assessment by rating agencies of our ability to pay our debts when due. Consequently, real or anticipated changes in our credit ratings will generally affect the market value of the Notes. These credit ratings may not reflect the potential impact of risks relating to the structure or marketing of the Notes. Credit ratings are not a recommendation to buy, sell or hold any security, and may be revised or withdrawn at any time by the issuing organization in its sole discretion. We undertake no obligation to maintain our credit ratings or to advise holders of Notes of any changes in our credit ratings. The Notes are currently rated by Standard & Poor's Ratings Services. There can be no assurance that our credit ratings will remain for any given period of time or that such credit ratings will not be lowered or withdrawn entirely by the rating agency if in their judgment future circumstances relating to the basis of the credit ratings, such as adverse changes in our company, so warrant. The conditions of the financial markets and prevailing interest rates have fluctuated in the past and are likely to fluctuate in the future, which could have an adverse effect on the market prices of the Notes.

The indentures under which the Notes were issued contain limited protection for holders of the Notes.

The indentures under which the Notes were issued offer limited protection to holders of the Notes. The terms of the indentures and the Notes do not restrict our or any of our subsidiaries' ability to engage in, or otherwise be a party to, a variety of corporate transactions, circumstances or events that could have an adverse impact on investments in the Notes. In particular, the terms of the indentures and the Notes do not place any restrictions on our or our subsidiaries' ability to:

•

issue securities or otherwise incur additional indebtedness or other obligations, including (1) any indebtedness or other obligations that would be equal in right of payment to the Notes, (2) any indebtedness or other obligations that would be secured and therefore rank effectively senior in right of payment to the Notes to the extent of the values of the assets securing such debt, (3) indebtedness of ours that is guaranteed by one or more of our subsidiaries and which therefore is structurally senior to the Notes and (4) securities, indebtedness or obligations issued or incurred by our subsidiaries that would be senior to our equity interests in our subsidiaries and therefore rank structurally senior to the Notes with respect to the assets of our subsidiaries, in each case other than an incurrence of indebtedness or other obligation that would cause a violation of Section 18(a)(1)(A) as modified by Section 61(a)(1) of the 1940 Act or any successor provisions, but giving effect, in each case, to any exemptive relief granted to us by the SEC (currently, this provision generally prohibits us from making additional borrowings, including through the issuance of additional debt or the sale of additional debt securities, unless our asset coverage, as defined in the 1940 Act, equals at least 200% (or 150% if certain requirements are met) after such borrowings);



•

pay dividends on, or purchase or redeem or make any payments in respect of, capital stock or other securities ranking junior in right of payment to the Notes, including subordinated indebtedness;



•

sell assets (other than certain limited restrictions on our ability to consolidate, merge or sell all or substantially all of our assets);



•

enter into transactions with affiliates;



•

create liens (including liens on the shares of our subsidiaries) or enter into sale and leaseback transactions;



•

make investments; or



•

create restrictions on the payment of dividends or other amounts to us from our subsidiaries.

Furthermore, the terms of the indentures and the Notes do not protect holders of the Notes in the event that we experience changes (including significant adverse changes) in our financial condition, results of operations or credit ratings, if any, as they do not require that we or our subsidiaries adhere to any financial tests or ratios or specified levels of net worth, revenues, income, cash flow or liquidity.

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Our ability to recapitalize, incur additional debt and take a number of other actions that are not limited by the terms of the Notes may have important consequences for you as a holder of the Notes, including making it more difficult for us to satisfy our obligations with respect to the Notes or negatively affecting the trading value of the Notes.

Other debt we issue or incur in the future could contain more protections for its holders than the indentures and the Notes, including additional covenants and events of default. For example, the indentures under which the Notes are issued do not contain cross-default provisions that are contained in the Credit Facility. The issuance or incurrence of any such debt with incremental protections could affect the market for and trading levels and prices of the Notes.

The optional redemption provision may materially adversely affect your return on the Notes.

The Notes are redeemable in whole or in part upon certain conditions at any time or from time to time at our option. We may choose to redeem the Notes at times when prevailing interest rates are lower than the interest rate paid on the Notes. In this circumstance, you may not be able to reinvest the redemption proceeds in a comparable security at an effective interest rate as high as the Notes being redeemed.

We may not be able to repurchase the Notes upon a Change of Control Repurchase Event.

We may not be able to repurchase the Notes upon certain change in control events described in the indentures under which the Notes were issued (each, a "Change of Control Repurchase Event") because we may not have sufficient funds. Upon a Change of Control Repurchase Event, holders of the Notes may require us to repurchase for cash some or all of the Notes at a repurchase price equal to 100% of the aggregate principal amount of the Notes being repurchased, plus accrued and unpaid interest to, but not including, the repurchase date. The terms of our Credit Facility provide that certain change of control events will constitute an event of default thereunder entitling the lenders to accelerate any indebtedness outstanding under our Credit Facility at that time and to terminate the Credit Facility. In addition, the occurrence of a Change of Control Repurchase Event enabling the holders of the Notes to require the mandatory purchase of the Notes would constitute an event of default under our Credit Facility entitling the lenders to accelerate any indebtedness outstanding under our Credit Facility at that time and to terminate the Credit Facility. Our and our subsidiaries' future financing facilities may contain similar restrictions and provisions. Our failure to purchase such tendered Notes upon the occurrence of such Change of Control Repurchase Event would cause an event of default under the indentures governing the Notes and a cross-default under the agreements governing certain of our other indebtedness, which may result in the acceleration of such indebtedness requiring us to repay that indebtedness immediately. If a Change of Control Repurchase Event were to occur, we may not have sufficient funds to repay any such accelerated indebtedness.

If we default on our obligations to pay our other indebtedness, we may not be able to make payments on the Notes.

As of December 31, 2018, we had approximately $1,006.8 million of principal indebtedness, including $301.0 million outstanding under the Credit Facility, $345.8 million outstanding from SBA-guaranteed debentures, $175.0 million of the 4.50% Notes due 2019 and $185.0 million of the 4.50% Notes due 2022 outstanding. Any default under the agreements governing our indebtedness, including a default under the Credit Facility, under the Notes or under other indebtedness to which we may be a party that is not waived by the required lenders or debt holders, and the remedies sought by the holders of such indebtedness could make us unable to pay principal, premium, if any, and interest on the Notes and substantially decrease the market value of the Notes. If we are unable to generate sufficient cash flow and are otherwise unable to obtain funds necessary to meet required payments of principal, premium, if any, and interest on our indebtedness, or if we otherwise fail to comply with the various covenants, including financial and operating covenants, in the instruments governing our indebtedness, we could be in default under the terms of the agreements governing such indebtedness. In the event of such default, the holders of such indebtedness could elect to declare all the funds borrowed thereunder to be due and payable, together with accrued and unpaid interest, the lenders

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under the Credit Facility or other debt we may incur in the future could elect to terminate their commitments, cease making further loans and institute foreclosure proceedings against our assets, and we could be forced into bankruptcy or liquidation. Our ability to generate sufficient cash flow in the future is, to some extent, subject to general economic, financial, competitive, legislative and regulatory factors as well as other factors that are beyond our control. We cannot assure you that our business will generate cash flow from operations, or that future borrowings will be available to us under the Credit Facility or otherwise, in an amount sufficient to enable us to meet our payment obligations under the Notes and our other debt and to fund other liquidity needs.

If our operating performance declines and we are not able to generate sufficient cash flow to service our debt obligations, we may in the future need to refinance or restructure our debt, including the Notes, sell assets, reduce or delay capital investments, seek to raise additional capital or seek to obtain waivers from the required lenders under the Credit Facility or the required holders of the Notes or other debt that we may incur in the future to avoid being in default. If we are unable to implement one or more of these alternatives, we may not be able to meet our payment obligations under the Notes and our other debt. If we breach our covenants under the Credit Facility, the Notes or other debt and seek a waiver, we may not be able to obtain a waiver from the required lenders or debt holders. If this occurs, we would be in default under the Credit Facility, the Notes or other debt, the lenders or debt holders could exercise their rights as described above, and we could be forced into bankruptcy or liquidation. If we are unable to repay debt, lenders having secured obligations could proceed against the collateral securing the debt. Because the Credit Facility has, and any future credit facilities will likely have, customary cross-default provisions, if the indebtedness under the Notes, the Credit Facility or under any future credit facility is accelerated, we may be unable to repay or finance the amounts due.

We may in the future determine to issue preferred stock, which could adversely affect the market value of our common stock.

The issuance of shares of preferred stock with dividend or conversion rights, liquidation preferences or other economic terms favorable to the holders of preferred stock could adversely affect the market price for our common stock by making an investment in the common stock less attractive. In addition, the dividends on any preferred stock we issue must be cumulative. Payment of dividends and repayment of the liquidation preference of preferred stock must take preference over any dividends or other payments to our common stockholders, and holders of preferred stock are not subject to any of our expenses or losses and are not entitled to participate in any income or appreciation in excess of their stated preference (other than convertible preferred stock that converts into common stock). In addition, under the 1940 Act, preferred stock constitutes a "senior security" for purposes of the asset coverage test.

Item 1B. Unresolved Staff Comments

None.

Item 2. Properties

We do not own any real estate or other physical properties materially important to our operations. Currently, we lease office space in Houston, Texas for our corporate headquarters.

Item 3. Legal Proceedings

We may, from time to time, be involved in litigation arising out of our operations in the normal course of business or otherwise. Furthermore, third parties may seek to impose liability on us in connection with the activities of our portfolio companies. While the outcome of any current legal proceedings cannot at this time be predicted with certainty, we do not expect any current matters will materially affect our financial condition or results of operations; however, there can be no assurance whether any pending legal proceedings will have a material adverse effect on our financial condition or results of operations in any future reporting period.

Item 4. Mine Safety Disclosures

Not applicable.

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PART II

Item 5. Market for Registrant's Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities

COMMON STOCK, HOLDERS AND DISTRIBUTIONS

Our common stock is traded on the New York Stock Exchange ("NYSE") under the symbol "MAIN." Prior to October 14, 2010, our common stock was traded on the NASDAQ Global Select Market under the same symbol "MAIN." Our common stock began trading on the NASDAQ Global Select Market on October 5, 2007. Prior to that date, there was no established public trading market for our common stock.

On February 27, 2019, there were approximately 346 holders of record of the common stock which did not include stockholders for whom shares are held in "nominee" or "street name."

Shares of BDCs may trade at a market price that is less than the value of the net assets attributable to those shares. The possibility that our shares of common stock will trade at a discount from net asset value per share or at premiums that are unsustainable over the long term are separate and distinct from the risk that our net asset value per share will decrease. It is not possible to predict whether our common stock will trade at, above, or below net asset value per share. Since our IPO in October 2007, our shares of common stock have traded at prices both less than and exceeding our net asset value per share.

We currently pay regular monthly dividends and semiannual supplemental dividends to our stockholders. Our monthly dividends, if any, will be determined by our Board of Directors on a quarterly basis. Our semiannual supplemental dividends, if any, will also be determined by our Board of Directors on a periodic basis. During 2018, we paid supplemental dividends of $0.275 per share in each of June and December 2018, regular monthly dividends of $0.190 per share for each month of January through September 2018, regular monthly dividends of $0.195 per share for each month of October through December 2018, with such dividends totaling $2.845 per share. The 2018 regular monthly dividends of $2.295 per share, represent a 2.7% increase from the regular monthly dividends paid per share for the year ended 2017. For tax purposes, the 2018 dividends, which included the effects of dividends on an accrual basis, total $2.85 per share and were comprised of (i) ordinary income totaling approximately $2.270 per share, (ii) long term capital gain totaling approximately $0.375 per share, and (iii) qualified dividend income totaling approximately $0.205 per share. As we have previously discussed, it is our current intention to fully absorb our semi-annual supplemental dividends into our regular monthly dividends, and in the process maintain and grow our total combined dividends, by gradually reducing our semi-annual supplemental dividends while increasing our regular monthly dividends over multiple years beginning in 2019.

In accordance with the IRC sections 871(k) and 881(e), the following percentages represent the portion of our dividends that constitute interest related dividends and short-term capital gains dividends for non-U.S. residents and foreign corporations. Including the long-term capital gains discussed above, the following percentages represent the total dividends which are exempt from U.S. withholding tax.

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To the extent non-U.S. resident taxes were withheld on ordinary dividends distributed, this information may be considered in connection with any claims for refund of such taxes to be filed by the non-U.S. resident stockholder with the Internal Revenue Service.

To obtain and maintain RIC tax treatment, we must, among other things, distribute at least 90% of our net ordinary taxable income and realized net short-term capital gains in excess of realized net long-term capital losses, if any. We will be subject to a 4% non-deductible U.S. federal excise tax on certain undistributed taxable income unless we distribute in a timely manner an amount at least equal to the sum of (1) 98% of our net ordinary taxable income for each calendar year, (2) 98.2% of our capital gain net income for the one-year period ending December 31 in that calendar year and (3) any taxable income recognized, but not distributed, in preceding years on which we paid no U.S. federal income tax. Dividends declared and paid by us in a year will generally differ from taxable income for that year, as such dividends may include the distribution of current year taxable income, less amounts carried over into the following year, and the distribution of prior year taxable income carried over into and distributed in the current year. For amounts we carry over into the following year, we will be required to pay the 4% U.S. federal excise tax on the excess of 98% of our annual investment company taxable income and 98.2% of our capital gain net income over our distributions for the year. We may retain for investment some or all of our net capital gains (i.e., realized net long-term capital gains in excess of realized net short-term capital losses) and treat such amounts as deemed distributions to our stockholders. If we do this, our stockholders will be treated as if they had received actual distributions of the capital gains we retained and then reinvested the net after-tax proceeds in our common stock. In general, our stockholders also would be eligible to claim a tax credit (or, in certain circumstances, a tax refund) equal to their allocable shares of the tax we paid on the capital gains deemed distributed to them. We can offer no assurance that we will achieve results that will permit the payment of any cash distributions and, if we issue senior securities, we may be prohibited from making distributions if doing so causes us to fail to maintain the asset coverage ratios stipulated by the 1940 Act or if distributions are limited by the terms of any of our borrowings.

We may distribute taxable dividends that are payable in part in our stock. Under certain applicable provisions of the Code and the Treasury regulations, distributions payable by us in cash or in shares of stock (at the stockholders election) would satisfy the Annual Distribution Requirement. The Internal Revenue Service has issued guidance providing that a dividend payable in stock or in cash at the election of the stockholders will be treated as a taxable dividend eligible for the dividends paid deduction provided that at least 20% of the total dividend is payable in cash and certain other requirements are satisfied. Taxable stockholders receiving such dividends will be required to include the full amount of the dividend as ordinary income (or as long-term capital gain to the extent such dividend is properly reported as a capital gain dividend), to the extent of our current and accumulated earnings and profits for U.S. federal income tax purposes. As a result, a U.S. stockholder may be required to pay tax with respect to such dividends in excess of any cash received. If a U.S. stockholder sells the stock it receives as a dividend in order to pay this tax, the sales proceeds may be less than the amount included in income with respect to the dividend, depending on the market price of our stock at the time of the sale. Furthermore, with respect to non-U.S. stockholders, we may be required to withhold U.S. tax with respect to such dividends, including in respect of all or a portion of such dividend that is payable in stock. In addition, if a significant number of our stockholders determine to sell shares of our stock in order to pay taxes owed on dividends, it may put downward pressure on the trading price of our stock.

We have adopted a dividend reinvestment plan ("DRIP") that provides for the reinvestment of dividends on behalf of our stockholders, unless a stockholder has elected to receive dividends in cash. As a result, if we declare a cash dividend, our stockholders who have not "opted out" of the DRIP by the dividend record date will have their cash dividend automatically reinvested into additional shares of MSCC common stock. The share requirements of the DRIP may be satisfied through the issuance of new shares of common stock or through open market purchases of common stock by the DRIP plan administrator. Newly issued shares will be valued based upon the final closing price of MSCC's common stock on a valuation date determined for each dividend by our Board of Directors. Shares purchased in the open market to satisfy the DRIP

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requirements will be valued based upon the average price of the applicable shares purchased by the DRIP plan administrator, before any associated brokerage or other costs. Our DRIP is administered by its transfer agent on behalf of our record holders and participating brokerage firms. Brokerage firms and other financial intermediaries may decide not to participate in our DRIP but may provide a similar dividend reinvestment plan for their clients.

SALES OF UNREGISTERED SECURITIES

During the year ended December 31, 2018, we issued a total of 394,403 shares of our common stock under the DRIP. These issuances were not subject to the registration requirements of the Securities Act of 1933, as amended. The aggregate value of the shares of our common stock issued under the DRIP during 2018 was approximately $14.9 million.

PURCHASES OF EQUITY SECURITIES

None.

STOCK PERFORMANCE GRAPH

The following graph compares the stockholder return on our common stock from October 5, 2007 to December 31, 2018 with the S&P 500 Index, the Russell 2000 Index, the KBW Regional Bank Index and the Main Street Peer Group (as defined below). This comparison assumes $100.00 was invested on October 5, 2007 (the date our common stock began to trade in connection with our initial public offering) in our common stock and in the comparison groups and assumes the reinvestment of all cash dividends prior to any tax effect. The comparisons in the graph below are based on historical data and are not intended to forecast the possible future performance of our common stock.

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COMPARISON OF STOCKHOLDER RETURN(1)
Among Main Street Capital Corporation, the S&P 500 Index, the Russell 2000 Index, the KBW
Regional Bank Index, and the Main Street Peer Group(2)
(For the Period October 5, 2007 to December 31, 2018)

TOTAL RETURN PERFORMANCE SINCE IPO

(1)

Total return includes reinvestment of dividends through December 31, 2018.

(2)

The Main Street Peer Group is composed of Apollo Investment Corporation, Ares Capital Corporation, BlackRock Capital Investment Corporation, Blackrock TCP Capital Corp., Capitala Finance Corp., Fidus Investment Corporation, FS KKR Capital Corp., Gladstone Investment Corporation, Goldman Sachs BDC, Inc., Golub Capital BDC, Inc., Hercules Capital, Inc., Medley Capital Corporation, Monroe Capital Corporation, New Mountain Finance Corporation, Newtek Business Services Corp., Oaktree Specialty Lending Corporation, Oaktree Strategic Income Corporation, PennantPark Floating Rate Capital Ltd., PennantPark Investment Corporation, Prospect Capital Corporation, Solar Capital Ltd., Solar Senior Capital Ltd., THL Credit, Inc., TPG Specialty Lending, Inc. and TriplePoint Venture Growth BDC Corp.

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Item 6. Selected Financial Data

The selected financial and other data as of and for the years ended December 31, 2018, 2017, 2016, 2015 and 2014 have been derived from consolidated financial statements that have been audited by Grant Thornton LLP, an independent registered public accounting firm. You should read this selected financial and other data in conjunction with our "Management's Discussion and Analysis of Financial Condition and Results of Operations" and the consolidated financial statements and related notes included in this Annual Report on Form 10-K.

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Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations

The following discussion should be read in conjunction with our consolidated financial statements and the notes thereto included elsewhere in this Annual Report on Form 10-K.

Statements we make in the following discussion which express a belief, expectation or intention, as well as those that are not historical fact, are forward-looking statements that are subject to risks, uncertainties and assumptions. Our actual results, performance or achievements, or industry results, could differ materially from those we express in the following discussion as a result of a variety of factors, including the risks and uncertainties we have referred to under the headings "Cautionary Statement Concerning Forward-Looking Statements" and "Risk Factors" in Part I of this report.

ORGANIZATION

Main Street Capital Corporation ("MSCC") is a principal investment firm primarily focused on providing customized debt and equity financing to lower middle market ("LMM") companies and debt capital to middle market ("Middle Market") companies. The portfolio investments of MSCC and its consolidated subsidiaries are typically made to support management buyouts, recapitalizations, growth financings, refinancings and acquisitions of companies that operate in a variety of industry sectors. MSCC seeks to partner with entrepreneurs, business owners and management teams and generally provides "one stop" financing alternatives within its LMM portfolio. MSCC and its consolidated subsidiaries invest primarily in secured debt investments, equity investments, warrants and other securities of LMM companies based in the United States and in secured debt investments of Middle Market companies generally headquartered in the United States.

MSCC was formed in March 2007 to operate as an internally managed business development company ("BDC") under the Investment Company Act of 1940, as amended (the "1940 Act"). MSCC wholly owns several investment funds, including Main Street Mezzanine Fund, LP ("MSMF"), Main Street Capital II, LP ("MSC II") and Main Street Capital III, LP ("MSC III" and, collectively with MSMF and MSC II, the "Funds"), and each of their general partners. The Funds are each licensed as a Small Business Investment Company ("SBIC") by the United States Small Business Administration ("SBA"). Because MSCC is internally managed, all of the executive officers and other employees are employed by MSCC. Therefore, MSCC does not pay any external investment advisory fees, but instead directly incurs the operating costs associated with employing investment and portfolio management professionals.

MSC Adviser I, LLC (the "External Investment Manager") was formed in November 2013 as a wholly owned subsidiary of MSCC to provide investment management and other services to parties other than MSCC and its subsidiaries or their portfolio companies ("External Parties") and receives fee income for such services. MSCC has been granted no-action relief by the Securities and Exchange Commission ("SEC") to allow the External Investment Manager to register as a registered investment adviser under the Investment Advisers Act of 1940, as amended. Since the External Investment Manager conducts all of its investment management activities for External Parties, it is accounted for as a portfolio investment of MSCC and is not included as a consolidated subsidiary of MSCC in MSCC's consolidated financial statements.

MSCC has elected to be treated for U.S. federal income tax purposes as a regulated investment company ("RIC") under Subchapter M of the Internal Revenue Code of 1986, as amended (the "Code"). As a result, MSCC generally will not pay corporate-level U.S. federal income taxes on any net ordinary taxable income or capital gains that it distributes to its stockholders.

MSCC has certain direct and indirect wholly owned subsidiaries that have elected to be taxable entities (the "Taxable Subsidiaries"). The primary purpose of the Taxable Subsidiaries is to permit MSCC to hold equity investments in portfolio companies which are "pass-through" entities for tax purposes.

Unless otherwise noted or the context otherwise indicates, the terms "we," "us," "our," the "Company" and "Main Street" refer to MSCC and its consolidated subsidiaries, which include the Funds and the Taxable Subsidiaries.

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OVERVIEW

Our principal investment objective is to maximize our portfolio's total return by generating current income from our debt investments and capital appreciation from our equity and equity-related investments, including warrants, convertible securities and other rights to acquire equity securities in a portfolio company. Our LMM companies generally have annual revenues between $10 million and $150 million, and our LMM portfolio investments generally range in size from $5 million to $50 million. Our Middle Market investments are made in businesses that are generally larger in size than our LMM portfolio companies, with annual revenues typically between $150 million and $1.5 billion, and our Middle Market investments generally range in size from $3 million to $20 million. Our private loan ("Private Loan") portfolio investments are primarily debt securities in privately held companies which have been originated through strategic relationships with other investment funds on a collaborative basis. Private Loan investments are typically similar in size, structure, terms and conditions to investments we hold in our LMM portfolio and Middle Market portfolio.

We seek to fill the financing gap for LMM businesses, which, historically, have had limited access to financing from commercial banks and other traditional sources. The underserved nature of the LMM creates the opportunity for us to meet the financing needs of LMM companies while also negotiating favorable transaction terms and equity participations. Our ability to invest across a company's capital structure, from secured loans to equity securities, allows us to offer portfolio companies a comprehensive suite of financing options, or a "one stop" financing solution. Providing customized, "one stop" financing solutions is important to LMM portfolio companies. We generally seek to partner directly with entrepreneurs, management teams and business owners in making our investments. Our LMM portfolio debt investments are generally secured by a first lien on the assets of the portfolio company and typically have a term of between five and seven years from the original investment date.

Our Middle Market portfolio investments primarily consist of direct investments in or secondary purchases of interest-bearing debt securities in privately held companies that are generally larger in size than the companies included in our LMM portfolio. Our Middle Market portfolio debt investments are generally secured by either a first or second priority lien on the assets of the portfolio company and typically have an expected duration of between three and seven years from the original investment date.

Our Private Loan portfolio investments are primarily debt securities in privately held companies which have been originated through strategic relationships with other investment funds on a collaborative basis, and are often referred to in the debt markets as "club deals." Private Loan investments are typically similar in size, structure, terms and conditions to investments we hold in our LMM portfolio and Middle Market portfolio. Our Private Loan portfolio debt investments are generally secured by either a first or second priority lien on the assets of the portfolio company and typically have a term of between three and seven years from the original investment date.

Our other portfolio ("Other Portfolio") investments primarily consist of investments which are not consistent with the typical profiles for our LMM, Middle Market or Private Loan portfolio investments, including investments which may be managed by third parties. In our Other Portfolio, we may incur indirect fees and expenses in connection with investments managed by third parties, such as investments in other investment companies or private funds.

Our external asset management business is conducted through the External Investment Manager. The External Investment Manager earns management fees based on the assets of the funds under management and may earn incentive fees, or a carried interest, based on the performance of the funds managed. We have entered into an agreement with the External Investment Manager to share employees in connection with its asset management business generally, and specifically for its relationship with HMS Income Fund, Inc. ("HMS Income"). Through this agreement, we share employees with the External Investment Manager, including their related infrastructure, business relationships, management expertise and capital raising capabilities.

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The following tables provide a summary of our investments in the LMM, Middle Market and Private Loan portfolios as of December 31, 2018 and 2017 (this information excludes the Other Portfolio investments and the External Investment Manager which are discussed further below):