Main Street Capital CORP

Previous wording

Main Street Capital Corporation (“MSCC” or, together with its consolidated subsidiaries, “Main Street” or the “Company”) is a principal investment firm primarily focused on providing customized long-term debt and equity capital solutions to lower middle market (“LMM”) companies (its “LMM investment strategy”) and debt capital to private (“Private Loan”) companies owned by or in the process of being acquired by a private equity fund (its “Private Loan investment strategy”). Main Street’s portfolio investments are typically made to support management buyouts, recapitalizations, growth financings, refinancings and acquisitions of companies that operate in diverse industry sectors. Main Street seeks to partner with entrepreneurs, business owners and management teams and generally provides “one-stop” debt and equity financing solutions within its LMM investment strategy. Main Street invests primarily in secured debt investments, equity investments, warrants and other securities of LMM companies typically based in the United States. Main Street also seeks to partner with private equity fund sponsors in its Private Loan investment strategy and primarily invests in secured debt investments of Private Loan companies generally headquartered in the United States.

Current wording

Main Street Capital Corporation (“MSCC” or, together with its consolidated subsidiaries, “Main Street” or the “Company”) is a principal investment firm primarily focused on providing customized long-term debt and equity capital solutions to lower middle market (“LMM”) companies (its “LMM investment strategy”) and debt capital to private (“Private Loan”) companies owned by or in the process of being acquired by a private equity fund (its “Private Loan investment strategy”). Main Street’s portfolio investments are typically made to support management buyouts, recapitalizations, growth financings, refinancings and acquisitions of companies that operate in diverse industry sectors. Main Street seeks to partner with entrepreneurs, business owners and management teams and generally provides “one-stop” debt and equity financing solutions within its LMM investment strategy. Main Street invests primarily in secured debt investments, equity investments, warrants and other securities of LMM companies typically based in the U.S. Main Street also seeks to partner with private equity fund sponsors in its Private Loan investment strategy and primarily invests in secured debt investments of Private Loan companies generally headquartered in the U.S.

Previous wording

The “Investment Portfolio,” as used herein, refers to all of Main Street’s investments in LMM portfolio companies, investments in Private Loan portfolio companies, investments in Middle Market portfolio companies, Other Portfolio investments, short-term portfolio investments (as discussed in Note C — Fair Value Hierarchy for Investments — Portfolio Composition — Investment Portfolio Composition in the notes to the consolidated financial statements included in Item 1. Consolidated Financial Statements of this Quarterly Report on Form 10-Q) and the investment in the External Investment Manager (as defined below).

Current wording

The “Investment Portfolio,” as used herein, refers to all of Main Street’s investments in LMM portfolio companies, investments in Private Loan portfolio companies, investments in Middle Market portfolio companies, Other Portfolio investments, short-term portfolio investments (see Note C — Fair Value Hierarchy for Investments — Portfolio Composition — Investment Portfolio Composition in the notes to the consolidated financial statements included in Item 1. Consolidated Financial Statements of this Quarterly Report on Form 10-Q) and the investment in the External Investment Manager (as defined below).

Previous wording

MSCC wholly owns several investment funds, including Main Street Mezzanine Fund, LP (“MSMF”) and Main Street Capital III, LP (“MSC III” and, together with MSMF, 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”).

Current wording

MSCC wholly owns several investment funds, including Main Street Mezzanine Fund, LP (“MSMF”) and Main Street Capital III, LP (“MSC III” and, together with MSMF, the “Funds”), and each of their general partners. The Funds are each licensed as a Small Business Investment Company (“SBIC”) by the U.S. Small Business Administration (“SBA”).

Previous wording

Our Other Portfolio investments primarily consist of investments that are not consistent with the typical profiles for our LMM, Private Loan or Middle Market 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.

Current wording

Our Other Portfolio investments primarily consist of investments that are not consistent with the typical profiles for our LMM, Private Loan or Middle Market portfolio investments, including investments in unaffiliated investment companies and private funds 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.

Previous wording

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 better alignment of interests between our management team and our employees and our stockholders and 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 and our External Investment Manager’s asset management business (as described below). The ratio of our total operating expenses, excluding interest expense, as a percentage of our quarterly average total assets was 1.3% for each of the trailing twelve months ended September 30, 2025 and 2024 and for the year ended December 31, 2024. The ratio of our total operating expenses, including interest expense, as a percentage of our quarterly average total assets was 3.8% and 3.7% for the trailing twelve months ended September 30, 2025 and 2024, respectively, and 3.8% for the year ended December 31, 2024. Our ratio of expenses as a percentage of our average net asset value (“NAV”) is described in greater detail in Note F — Financial Highlights in the notes to the consolidated financial statements included in Item 1. Consolidated Financial Statements of this Quarterly Report on Form 10-Q.

Current wording

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 better alignment of interests between our management team and our employees and our stockholders and 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 and our External Investment Manager’s asset management business (as described below). The ratio of our total operating expenses, excluding interest expense, as a percentage of our quarterly average total assets was 1.3% for each of the trailing twelve months ended March 31, 2026 and 2025 and for the year ended December 31, 2025. The ratio of our total operating expenses, including interest expense, as a percentage of our quarterly average total assets was 3.7% and 3.8% for the trailing twelve months ended March 31, 2026 and 2025, respectively, and 3.7% for the year ended December 31, 2025. Our ratio of expenses as a percentage of our average net asset value (“NAV”) is described in greater detail in Note F — Financial Highlights in the notes to the consolidated financial statements included in Item 1. Consolidated Financial Statements of this Quarterly Report on Form 10-Q.

Previous wording

The External Investment Manager earns management fees based on the assets of the funds and accounts under management and may earn incentive fees, or a carried interest, based on the performance of the funds and accounts managed. For the three months ended September 30, 2025 and 2024, the External Investment Manager earned $5.6 million and $6.1 million in base management fees, respectively, $3.9 million and $2.4 million in incentive fees, respectively, and $0.2 million of administrative service fee income for each of the three months ended September 30, 2025 and 2024. For the nine months ended September 30, 2025 and 2024, the External Investment Manager earned $17.1 million and $17.7 million in base management fees, respectively, $10.3 million and $10.4 million in incentive fees, respectively, and $0.5 million of administrative service fee income for each of the nine months ended September 30, 2025 and 2024.

Current wording

The External Investment Manager earns management fees based on the assets of the funds and accounts under management and may earn incentive fees, or a carried interest, based on the performance of the funds and accounts managed. For the three months ended March 31, 2026 and 2025, the External Investment Manager earned $6.1 million and $5.8 million in base management fees, respectively, $3.0 million and $2.7 million in incentive fees, net of waivers, respectively, and $0.2 million of administrative service fee income for each of the three months ended March 31, 2026 and 2025. For the three months ended March 31, 2026, the External Investment Manager waived $1.0 million of incentive fees on income related to MSC Income. As of March 31, 2026, MSC Income had an expense accrual of $2.1 million of incentive fees on capital gains to the External Investment Manager. However, no capital gains incentive fees were currently contractually payable to the External Investment Manager as of March 31, 2026 and as a result no amounts were accrued by the External Investment Manager.

Previous wording

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 MSC Income and its other clients. Through this agreement, we share employees with the External Investment Manager, including their related infrastructure, business relationships, management expertise and capital raising capabilities, and we allocate the related expenses to the External Investment Manager pursuant to the sharing agreement. Our total expenses for the three months ended September 30, 2025 and 2024 are net of expenses allocated to the External Investment Manager of $5.7 million and $5.3 million, respectively. Our total expenses for the nine months ended September 30, 2025 and 2024 are net of expenses allocated to the External Investment Manager of $17.0 million and $16.8 million, respectively.

Current wording

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 MSC Income and its other clients. Through this agreement, we share employees with the External Investment Manager, including their related infrastructure, business relationships, management expertise and capital raising capabilities, and we allocate the related expenses to the External Investment Manager pursuant to the sharing agreement. Our total expenses for the three months ended March 31, 2026 and 2025 are net of expenses allocated to the External Investment Manager of $5.5 million and $5.3 million, respectively.

Previous wording

The total contribution of the External Investment Manager to our net investment income consists of the combination of the expenses allocated to the External Investment Manager and the dividend income earned from the External Investment Manager. For the three months ended September 30, 2025 and 2024, dividends accrued by us from the External Investment Manager were $3.0 million and $2.6 million, respectively. For the three months ended September 30, 2025 and 2024, the total contribution of the External Investment Manager to our net investment income was $8.8 million and $7.9 million, respectively. For the nine months ended September 30, 2025 and 2024, dividends accrued by us from the External Investment Manager were $8.4 million and $8.9 million, respectively. For the nine months ended September 30, 2025 and 2024, the total contribution of the External Investment Manager to our net investment income was $25.4 million and $25.6 million, respectively.

Current wording

The total contribution of the External Investment Manager to our net investment income consists of the combination of the expenses allocated to the External Investment Manager and the dividend income earned from the External Investment Manager. For the three months ended March 31, 2026 and 2025, dividends earned by us from the External Investment Manager were $2.9 million and $2.5 million, respectively. For the three months ended March 31, 2026 and 2025, the total contribution of the External Investment Manager to our net investment income was $8.3 million and $7.8 million, respectively.

Previous wording

We have received an exemptive order from the SEC permitting co-investments among us, MSC Income and other advisory clients of the External Investment Manager in certain negotiated transactions where co-investing would otherwise be prohibited under the 1940 Act. We have made co-investments with, and in the future intend to continue to make co-investments with MSC Income, Private Loan Fund I, Private Loan Fund II and other advisory clients of the External Investment Manager, 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 us and the External Investment Manager’s advised clients, as applicable, and if it is appropriate, to propose an allocation of the investment opportunity between such parties. Because the External Investment Manager may earn performance-based fee compensation from its advisory clients, this may provide the Company and the External Investment Manager an incentive to allocate opportunities to advisory clients instead of us. However, both we and the External Investment Manager have policies and procedures in place to manage this conflict, including approval of investment allocations and oversight of co-investments by the independent members of our Board of Directors. In addition to the co-investment program described above, we also co-invest in certain investment transactions where price is the only negotiated point by us and our affiliates.

Current wording

We have received an exemptive order from the SEC permitting co-investments among us, MSC Income and other advisory clients of the External Investment Manager in certain negotiated transactions where co-investing would otherwise be prohibited under the 1940 Act. We have made co-investments with, and in the future intend to continue to make co-investments with MSC Income, Private Loan Fund I, Private Loan Fund II and other advisory clients of the External Investment Manager, in accordance with the conditions of the order. Because the External Investment Manager may earn performance-based fee compensation from its advisory clients, this may provide the Company and the External Investment Manager an incentive to allocate opportunities to advisory clients instead of us. However, both we and the External Investment Manager have adopted policies and procedures pursuant to the order to manage this conflict and ensure that investment opportunities are allocated in a manner that is fair and equitable considering each investor’s interests, including oversight of the co-investment program by the independent members of our and MSC Income’s boards of directors and their required approval of certain co-investment transactions thereunder. In addition to the co-investment program described above, we also co-invest in certain investment transactions where price is the only negotiated point by us and our affiliates.

Previous wording

The following tables provide a summary of our investments in the LMM and Private Loan portfolios as of September 30, 2025 and December 31, 2024 (this information excludes Middle Market, Other Portfolio investments and the External Investment Manager, which are discussed further below).

Current wording

A summary of our LMM and Private Loan portfolio investments as of March 31, 2026 and December 31, 2025 is as follows (this information excludes Middle Market portfolio investments, Other Portfolio investments and the External Investment Manager, which are discussed further below):

Previous wording

(a)As of September 30, 2025, we had equity ownership in all of our LMM portfolio companies, and the average fully diluted equity ownership in those portfolio companies was 38%.

Current wording

(a)As of March 31, 2026, we had equity ownership in all of our LMM portfolio companies, and the average fully diluted equity ownership in those portfolio companies was 36%.

Previous wording

(b)The weighted-average annual effective yields were computed using the effective interest rates for all debt investments as of September 30, 2025, including amortization of deferred debt origination fees and accretion of original issue discount but excluding fees payable upon repayment of the debt instruments and any debt investments on non-accrual status, and are weighted based upon the principal amount of each applicable debt investment as of September 30, 2025. The weighted-average annual effective yield on our debt portfolio as of September 30, 2025, including debt investments on non-accrual status, was 12.1% for our LMM portfolio and 10.1% for our Private Loan portfolio. The weighted-average annual effective yield is not reflective of what an investor in shares of our common stock will realize on its investment because it does not reflect changes in the market value of our stock, our utilization of debt capital in our capital structure, our expenses or any sales load paid by an investor.

Current wording

(b)The weighted-average annual effective yields were computed using the effective interest rates for all debt investments as of March 31, 2026, including amortization of deferred debt origination fees and accretion of original issue discount but excluding fees payable upon repayment of the debt investments and any debt investments on non-accrual status, and are weighted based upon the principal amount of each applicable debt investment as of March 31, 2026. The weighted-average annual effective yield on our debt portfolio as of March 31, 2026, including debt investments on non-accrual status, was 12.1% for our LMM portfolio investments and 9.7% for our Private Loan portfolio investments. The weighted-average annual effective yield is not reflective of what an investor in shares of our common stock will realize on their investment because it does not reflect changes in the market value of our stock, our utilization of debt capital in our capital structure, our expenses or any sales load paid by an investor.

Previous wording

(c)The average EBITDA is calculated using a simple average for the LMM portfolio and a weighted-average for the Private Loan portfolio. These calculations exclude certain portfolio companies, including five LMM portfolio companies and six Private Loan portfolio companies, as EBITDA is not a meaningful valuation metric for our investments in these portfolio companies, and those portfolio companies whose primary purpose is to own real estate and those portfolio companies whose primary operations have ceased and only residual value remains.

Current wording

(c)The average EBITDA is calculated using a simple average for LMM portfolio companies and a weighted-average for Private Loan portfolio companies. These calculations exclude certain portfolio companies, including five LMM portfolio companies and six Private Loan portfolio companies, as EBITDA is not a meaningful valuation metric for our investments in these portfolio companies, and those portfolio companies whose primary purpose is to own real estate and those portfolio companies whose primary operations have ceased and only residual value remains.

Previous wording

(a)As of December 31, 2024, we had equity ownership in all of our LMM portfolio companies, and the average fully diluted equity ownership in those portfolio companies was 38%.

Current wording

(a)As of December 31, 2025, we had equity ownership in all of our LMM portfolio companies, and the average fully diluted equity ownership in those portfolio companies was 37%.

Previous wording

(b)The weighted-average annual effective yields were computed using the effective interest rates for all debt investments as of December 31, 2024, including amortization of deferred debt origination fees and accretion of original issue discount but excluding fees payable upon repayment of the debt instruments and any debt investments on non-accrual status, and are weighted based upon the principal amount of each applicable debt investment as of December 31, 2024. The weighted-average annual effective yield on our debt portfolio as of December 31, 2024, including debt investments on non-accrual status, was 12.3% for our LMM portfolio and 11.5% for our Private Loan portfolio. The weighted-average annual effective yield is not reflective of what an investor in shares of our common stock will realize on its investment because it does not reflect changes in the market value of our stock, our utilization of debt capital in our capital structure, our expenses or any sales load paid by an investor.

Current wording

(b)The weighted-average annual effective yields were computed using the effective interest rates for all debt investments as of December 31, 2025, including amortization of deferred debt origination fees and accretion of original issue discount but excluding fees payable upon repayment of the debt investments and any debt investments on non-accrual status, and are weighted based upon the principal amount of each applicable debt investment as of December 31, 2025. The weighted-average annual effective yield on our debt portfolio as of December 31, 2025, including debt investments on non-accrual status, was 12.0% for our LMM portfolio investments and 10.1% for our Private Loan portfolio investments. The weighted-average annual effective yield is not reflective of what an investor in shares of our common stock will realize on their investment because it does not reflect changes in the market value of our stock, our utilization of debt capital in our capital structure, our expenses or any sales load paid by an investor.

Previous wording

(c)The average EBITDA is calculated using a simple average for the LMM portfolio and a weighted-average for the Private Loan portfolio. These calculations exclude certain portfolio companies, including five LMM portfolio companies and five Private Loan portfolio companies, as EBITDA is not a meaningful valuation metric for our investments in these portfolio companies, and those portfolio companies whose primary purpose is to own real estate and those portfolio companies whose primary operations have ceased and only residual value remains.

Current wording

(c)The average EBITDA is calculated using a simple average for LMM portfolio companies and a weighted-average for Private Loan portfolio companies. These calculations exclude certain portfolio companies, including five LMM portfolio companies and six Private Loan portfolio companies, as EBITDA is not a meaningful valuation metric for our investments in these portfolio companies, and those portfolio companies whose primary purpose is to own real estate and those portfolio companies whose primary operations have ceased and only residual value remains.

Previous wording

For the three months ended September 30, 2025 and 2024, we achieved an annualized total return on investments of 16.9% and 17.7%, respectively. For the nine months ended September 30, 2025 and 2024, we achieved an annualized total return on investments of 16.4% and 16.7%, respectively. For the year ended December 31, 2024, we achieved a total return on investments of 17.9%. Total return on investments is calculated using the interest, dividend and fee income, as well as the realized and unrealized change in fair value of the Investment Portfolio for the specified period. Our total return on investments is not reflective of what an investor in shares of our common stock will realize on its investment because it does not reflect changes in the market value of our stock, our utilization of debt capital in our capital structure, our expenses or any sales load paid by an investor.

Current wording

For the three months ended March 31, 2026 and 2025, we achieved an annualized total return on investments of 8.9% and 16.0%, respectively. For the year ended December 31, 2025, we achieved a total return on investments of 16.4%. Total return on investments equals the total interest, dividend and fee income plus realized and unrealized changes in the fair value of the Investment Portfolio divided by the average quarterly Investment Portfolio balance at cost, in each case for the specified period. Our total return on investments is not reflective of what an investor in shares of our common stock will realize on their investment because it does not reflect changes in the market value of our stock, our utilization of debt capital in our capital structure, our expenses or any sales load paid by an investor.

Previous wording

As of September 30, 2025, we had Other Portfolio investments in 32 entities, spread across 12 investment managers, collectively totaling $122.8 million in fair value and $130.9 million in cost basis, which comprised 2.4% and 3.0% of our Investment Portfolio at fair value and cost, respectively. As of December 31, 2024, we had Other Portfolio investments in 31 entities, spread across 12 investment managers, collectively totaling $124.1 million in fair value and $122.5 million in cost basis, which comprised 2.5% and 2.9% of our Investment Portfolio at fair value and cost, respectively.

Current wording

As of March 31, 2026, we had Other Portfolio investments in 34 entities, spread across 13 investment managers, collectively totaling $138.5 million in fair value and $148.5 million in cost basis, which comprised 2.4% and 3.0% of our Investment Portfolio at fair value and cost, respectively. As of December 31, 2025, we had Other Portfolio investments in 33 entities, spread across 13 investment managers, collectively totaling $134.1 million in fair value and $141.6 million in cost basis, which comprised 2.4% and 3.0% of our Investment Portfolio at fair value and cost, respectively.

Previous wording

As of September 30, 2025, we had Middle Market portfolio investments in 11 portfolio companies, collectively totaling $89.9 million in fair value and $119.8 million in cost basis, which comprised 1.7% and 2.8% of our Investment Portfolio at fair value and cost, respectively. As of December 31, 2024, we had Middle Market portfolio investments in 15 portfolio companies, collectively totaling $155.3 million in fair value and $195.0 million in cost basis, which comprised 3.1% and 4.6% of our Investment Portfolio at fair value and cost, respectively.

Current wording

As of March 31, 2026, we had Middle Market portfolio investments in 11 portfolio companies, collectively totaling $81.9 million in fair value and $121.4 million in cost basis, which comprised 1.4% and 2.5% of our Investment Portfolio at fair value and cost, respectively. As of December 31, 2025, we had Middle Market portfolio investments in 11 portfolio companies, collectively totaling $83.5 million in fair value and $120.1 million in cost basis, which comprised 1.5% and 2.5% of our Investment Portfolio at fair value and cost, respectively.

Previous wording

As previously discussed in Note A.1. — Organization and Basis of Presentation — Organizationin the notes to the consolidated financial statements included in Item 1. Consolidated Financial Statements of this Quarterly Report on Form 10-Q, we hold an investment in the External Investment Manager, a wholly-owned subsidiary that is treated as a portfolio investment. As of September 30, 2025, this investment had a fair value of $266.4 million and a cost basis of $29.5 million, which comprised 5.2% and 0.7% of our Investment Portfolio at fair value and cost, respectively. As of December 31, 2024, this investment had a fair value of $246.0 million and a cost basis of $29.5 million, which comprised 5.0% and 0.7% of our Investment Portfolio at fair value and cost, respectively.

Current wording

As previously discussed in Note A.1. — Organization and Basis of Presentation — Organizationin the notes to the consolidated financial statements included in Item 1. Consolidated Financial Statements of this Quarterly Report on Form 10-Q, we hold an investment in the External Investment Manager, a wholly-owned subsidiary that is treated as a portfolio investment. As of March 31, 2026, this investment had a fair value of $233.1 million and a cost basis of $29.5 million, which comprised 4.1% and 0.6% of our Investment Portfolio at fair value and cost, respectively. As of December 31, 2025, this investment had a fair value of $255.0 million and a cost basis of $29.5 million, which comprised 4.6% and 0.6% of our Investment Portfolio at fair value and cost, respectively.

Previous wording

The preparation of financial statements and related disclosures in conformity with generally accepted accounting principles (“U.S. GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and contingent assets and liabilities at the date of the financial statements, and revenues and expenses during the periods reported. Actual results could materially differ from those estimates. Critical accounting policies are those that require management to make subjective or complex judgments about the effect of matters that are inherently uncertain and may change in subsequent periods. Changes that may be required in the underlying assumptions or estimates in these areas could have a material impact on our current and future financial condition and results of operations.

Current wording

The preparation of financial statements and related disclosures in conformity with generally accepted accounting principles in the United States of America (“U.S. GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and contingent assets and liabilities as of the date of the financial statements, and revenues and expenses during the periods reported. Actual results could materially differ from those estimates. Critical accounting policies are those that require management to make subjective or complex judgments about the effect of matters that are inherently uncertain and may change in subsequent periods. Changes that may be required in the underlying assumptions or estimates in these areas could have a material impact on our current and future financial condition and results of operations.

Previous wording

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 consider this determination to be a critical accounting estimate, given the significant judgments and subjective measurements required. As of September 30, 2025 and December 31, 2024, our Investment Portfolio valued at fair value represented 97% and 96%, respectively, of our total assets. We are required to report our investments at fair value. We follow the provisions of Financial Accounting Standards Board (“FASB”) 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. See Note B.1. — Summary of Significant Accounting Policies — Valuation of the Investment Portfolioin the notes to the consolidated financial statements included in Item 1. Consolidated Financial Statements of this Quarterly Report on Form 10-Q for a detailed discussion of our Investment Portfolio valuation process and procedures.

Current wording

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 consider this determination to be a critical accounting estimate, given the significant judgments and subjective measurements required. As of both March 31, 2026 and December 31, 2025, our Investment Portfolio valued at fair value represented 97% of our total assets. We are required to report our investments at fair value. We follow the provisions of Financial Accounting Standards Board (“FASB”) 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. See Note B.1. — Summary of Significant Accounting Policies — Valuation of the Investment Portfolioin the notes to the consolidated financial statements included in Item 1. Consolidated Financial Statements of this Quarterly Report on Form 10-Q for a detailed discussion of our Valuation Procedures (as defined below).

Previous wording

We record interest and dividend income on the accrual basis to the extent amounts are expected to be collected. Dividend income is recorded as dividends are declared by the portfolio company or at the point an obligation exists for the portfolio company to make a distribution. We evaluate accrued interest and dividend income periodically for collectability. When a loan or debt security becomes 90 days or more past due, and if we otherwise do not expect the debtor to be able to service its debt obligation, we will generally place the loan or debt security on non-accrual status and cease recognizing interest income on that loan or debt security until the borrower has demonstrated the ability and intent to pay contractual amounts due. If a loan or debt security’s status significantly improves regarding the debtor’s ability to service the debt obligation, or if a loan or debt security is sold or written off, we remove it from non-accrual status.

Current wording

We record interest and dividend income on the accrual basis to the extent amounts are expected to be collected. Dividend income is recorded as dividends are declared by the portfolio company or at the point an obligation exists for the portfolio company to make a distribution. We evaluate accrued interest and dividend income periodically for collectability. When a loan or debt security becomes 90 days or more past due, and if we otherwise do not expect the debtor to be able to service its debt obligation, we will generally place the loan or debt security on non-accrual status and cease recognizing interest income on that loan or debt security until the borrower has demonstrated the ability and intent to pay contractual amounts due. If a loan or debt security’s status significantly improves regarding the debtor’s ability to service the debt obligation, or if a loan or debt security is sold or written off, we remove it from non-accrual status. Generally, any interest payments received for investments on non-accrual status reduce the cost basis of our investment and are not recorded as income.

Previous wording

We hold certain debt and preferred equity instruments in our Investment Portfolio that contain PIK interest and cumulative dividend provisions. The PIK interest, computed at the contractual rate specified in each debt agreement, is periodically added to the principal balance of the debt and is recorded as interest income. Thus, the actual collection of this interest may be deferred until the time of debt principal repayment. Cumulative dividends are recorded as dividend income, and any dividends in arrears are added to the balance of the preferred equity investment. The actual collection of these dividends in arrears may be deferred until such time as the preferred equity is redeemed or sold. To maintain RIC tax treatment (as discussed in Note B.10. — Summary of Significant Accounting Policies — Income Taxes in the notes to the consolidated financial statements included in Item 1. Consolidated Financial Statements of this Quarterly Report on Form 10-Q), these non-cash sources of income may need to be paid out to stockholders in the form of distributions, even though we may not have collected the PIK interest and cumulative dividends in cash. We stop accruing PIK interest and cumulative dividends and write off any accrued and uncollected interest and dividends in arrears when we determine that such PIK interest and dividends in arrears are no longer collectible. For the three months ended September 30, 2025 and 2024, (i) 3.0% and 4.4%, respectively, of our total investment income was attributable to PIK interest income not paid currently in cash and (ii) 0.7% and 0.5%, respectively, of our total investment income was attributable to cumulative dividend income not paid currently in cash. For the nine months ended September 30, 2025 and 2024, (i) 2.7% and 3.8%, respectively, of our total investment income was attributable to PIK interest income not paid currently in cash and (ii) 0.7% and 0.4%, respectively, of our total investment income was attributable to cumulative dividend income not paid currently in cash.

Current wording

We hold certain debt and preferred equity instruments in our Investment Portfolio that contain PIK interest and cumulative dividend provisions. The PIK interest, computed at the contractual rate specified in each debt agreement, is periodically added to the principal balance of the debt and is recorded as interest income. Thus, the actual collection of this interest may be deferred until the time of debt principal repayment. Cumulative dividends are recorded as dividend income, and any dividends in arrears are added to the balance of the preferred equity investment. The actual collection of these dividends in arrears may be deferred until such time as the preferred equity is redeemed or sold. To maintain RIC tax treatment (see Note B.10. — Summary of Significant Accounting Policies — Income Taxes in the notes to the consolidated financial statements included in Item 1. Consolidated Financial Statements of this Quarterly Report on Form 10-Q), these non-cash sources of income may need to be paid out to stockholders in the form of distributions, even though we may not have collected the PIK interest and cumulative dividends in cash. We stop accruing PIK interest and cumulative dividends and write off any accrued and uncollected interest and dividends in arrears when we determine that such PIK interest and dividends in arrears are no longer collectible. For the three months ended March 31, 2026 and 2025, (i) 2.7% and 2.9%, respectively, of our total investment income was attributable to PIK interest income not paid currently in cash and (ii) 0.7% and 0.5%, respectively, of our total investment income was attributable to cumulative dividend income not paid currently in cash.

Previous wording

The following tables summarize the composition of our total combined LMM, Private Loan and Middle Market portfolio investments at cost and fair value by type of investment as a percentage of the total combined LMM, Private Loan and Middle Market portfolio investments as of September 30, 2025 and December 31, 2024 (this information excludes Other Portfolio investments and the External Investment Manager, which are discussed above).

Current wording

A summary of the composition of our total combined LMM, Private Loan and Middle Market portfolio investments at cost and fair value by type of investment as a percentage of the total combined LMM, Private Loan and Middle Market portfolio investments as of March 31, 2026 and December 31, 2025 is as follows (this information excludes Other Portfolio investments and the External Investment Manager, which are discussed above):

Previous wording

Our LMM, Private Loan and Middle Market portfolio investments carry a number of risks including: (1) investing in companies which may have limited operating histories and financial resources; (2) holding investments that generally are not publicly traded and which may be subject to legal and other restrictions on resale; and (3) other risks common to investing in below investment-grade debt and equity investments in our Investment Portfolio. Please see Item 1A. Risk Factors contained in Part II of this Form 10-Q for further information.

Current wording

Our LMM, Private Loan and Middle Market portfolio investments carry a number of risks including: (1) investing in companies which may have limited operating histories and financial resources; (2) holding investments that generally are not publicly traded and which may be subject to legal and other restrictions on resale; and (3) other risks common to investing in below investment-grade debt and equity investments in our Investment Portfolio. See Item 1A. Risk Factors contained in Part II of this Form 10-Q for further information.

Previous wording

As of September 30, 2025, investments on non-accrual status comprised 1.2% of our total Investment Portfolio at fair value and 3.6% at cost. As of December 31, 2024, investments on non-accrual status comprised 0.9% of our total Investment Portfolio at fair value and 3.5% at cost.

Current wording

As of March 31, 2026, investments on non-accrual status were $68.3 million at fair value and $199.1 million at cost and comprised 1.2% and 4.0% of our total Investment Portfolio at fair value and cost, respectively. As of December 31, 2025, investments on non-accrual status were $56.3 million at fair value and $155.3 million at cost and comprised 1.0% and 3.3% of our total Investment Portfolio at fair value and cost, respectively.

Previous wording

The operating results of our portfolio companies are impacted by changes in the broader fundamentals of the United States economy. In periods during which 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, to an increase in defaults on our debt investments or in realized losses on our investments and to difficulty in maintaining historical dividend payment rates and unrealized appreciation on our equity investments. Consequently, we can provide no assurance that the performance of certain portfolio companies will not be negatively impacted by future economic cycles or other conditions, which could also have a negative impact on our future results.

Current wording

The operating results of our portfolio companies are impacted by changes in the broader fundamentals of the U.S. economy. In periods during which the U.S. 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, to an increase in defaults on our debt investments or in realized losses on our investments and to difficulty in maintaining historical dividend payment rates and unrealized appreciation on our equity investments. Consequently, we can provide no assurance that the performance of certain portfolio companies will not be negatively impacted by future economic cycles or other conditions, which could also have a negative impact on our future results.

Previous wording

Set forth below is a comparison of the results of operations, and a reconciliation of net investment income to distributable net investment income and to distributable net investment income before taxes, for the three months ended September 30, 2025 and 2024. All prior period net investment income, net investment income per share, distributable net investment income and distributable net investment income per share amounts presented in this section have been retrospectively adjusted to conform to the current presentation. See Note A.3. — Organization and Basis of Presentation — Revisions to the Presentation of Previously Issued Financial Statements in the notes to the consolidated financial statements included in Item 1. Consolidated Financial Statements of this Quarterly Report on Form 10-Q for additional details on these adjustments.

Current wording

Set forth below is a comparison of the results of operations and a reconciliation of net investment income to distributable net investment income and to distributable net investment income before taxes for the three months ended March 31, 2026 and 2025.

Previous wording

(a)Distributable net investment income is net investment income as determined in accordance with U.S. GAAP, excluding the impact of share-based compensation expense and deferred compensation expense or benefit. We believe presenting distributable net investment income and the related per share amounts is useful and appropriate supplemental disclosure for analyzing our financial performance since share-based compensation does not require settlement in cash and deferred compensation expense or benefit does not result in a net cash impact to Main Street upon settlement. However, distributable net investment income is a non-U.S. GAAP measure and should not be considered as a replacement for net investment income or other earnings measures presented in accordance with U.S. GAAP and should be reviewed only in connection with such U.S. GAAP measures in analyzing our financial performance. A reconciliation of net investment income in accordance with U.S. GAAP to distributable net investment income is detailed in the table above.

Current wording

(a)Distributable net investment income is net investment income as determined in accordance with U.S. GAAP, excluding the impact of share-based compensation expense and deferred compensation expense or benefit. We believe presenting distributable net investment income and the related per share amounts is useful and appropriate supplemental disclosure for analyzing our financial performance since (i) share-based compensation does not require settlement in cash and (ii) deferred compensation expense or benefit does not result in a net cash impact to Main Street upon settlement. However, distributable net investment income is a non-U.S. GAAP measure and should not be considered as a replacement for net investment income or other earnings measures presented in accordance with U.S. GAAP and should be reviewed only in connection with such U.S. GAAP measures in analyzing our financial performance. A reconciliation of net investment income in accordance with U.S. GAAP to distributable net investment income is detailed in the table above.

Previous wording

(b)Distributable net investment income before taxes is net investment income as determined in accordance with U.S. GAAP, excluding the impact of share-based compensation expense, deferred compensation expense or benefit and any tax expenses included in net investment income. We believe presenting distributable net investment income before taxes and the related per share amounts is useful and appropriate supplemental disclosure for analyzing our financial performance since share-based compensation does not require settlement in cash and deferred compensation expense or benefit does not result in a net cash impact to Main Street upon settlement, and since tax expenses included in net investment income may include excise tax expense, which is not solely attributable to net investment income, and deferred taxes, which are not payable in the current period. However, distributable net investment income before taxes is a non-U.S. GAAP measure and should not be considered as a replacement for net investment income, net investment income before taxes or other earnings measures presented in accordance with U.S. GAAP and should be reviewed only in connection with such U.S. GAAP measures in analyzing our financial performance. A reconciliation of net investment income in accordance with U.S. GAAP to distributable net investment income before taxes is detailed in the table above.

Current wording

(b)Distributable net investment income before taxes is net investment income as determined in accordance with U.S. GAAP, excluding the impact of share-based compensation expense, deferred compensation expense or benefit and any tax expenses included in net investment income. We believe presenting distributable net investment income before taxes and the related per share amounts is useful and appropriate supplemental disclosure for analyzing our financial performance since (i) share-based compensation does not require settlement in cash, (ii) deferred compensation expense or benefit does not result in a net cash impact to Main Street upon settlement and (iii) tax expenses included in net investment income may include (a) excise tax expense, which is not solely attributable to net investment income, and (b) deferred taxes, which are not payable in the current period. However, distributable net investment income before taxes is a non-U.S. GAAP measure and should not be considered as a replacement for net investment income, net investment income before taxes or other earnings measures presented in accordance with U.S. GAAP and should be reviewed only in connection with such U.S. GAAP measures in analyzing our financial performance. A reconciliation of net investment income in accordance with U.S. GAAP to distributable net investment income before taxes is detailed in the table above.

Previous wording

Total investment income for the three months ended September 30, 2025 was $139.8 million, a 2% increase from the $136.8 million of total investment income for the corresponding period of 2024. The following table provides a summary of the changes in the comparable period activity.

Current wording

Total investment income for the three months ended March 31, 2026 was $140.1 million, a 2% increase from the $137.0 million for the corresponding period of 2025. A summary of the changes in the comparable period activity is as follows:

Previous wording

(a)The decrease in interest income was primarily attributable to (i) an increase in investments on non-accrual status and (ii) a decrease in interest rates, primarily resulting from decreases in benchmark index interest rates on floating rate Investment Portfolio debt investments and decreases in interest rate spreads on existing Investment Portfolio debt investments, partially offset by higher average levels of income producing Investment Portfolio debt investments.

Current wording

(a)The increase in interest income was primarily attributable to higher average levels of income producing Investment Portfolio debt investments, partially offset by (i) a decrease in interest rates, primarily resulting from decreases in benchmark index interest rates on floating rate Investment Portfolio debt investments, and (ii) the negative impact from Investment Portfolio debt investments on non-accrual status.

Previous wording

(b)The increase in dividend income was primarily a result of (i) an increase of $31.2 million in dividend income from our LMM portfolio companies and (ii) an increase $2.1 million in dividend income from our Private Loan portfolio companies, partially offset by a decrease of $0.5 million in dividend income from our External Investment Manager.

Current wording

(b)The decrease in dividend income was primarily a result of dividend income decreases of (i) $8.0 million from our LMM portfolio companies and (ii) $0.7 million from our Private Loan portfolio companies, partially offset by a $0.6 million increase in dividend income from Other Portfolio investments.

Previous wording

(c)The increase in fee income was primarily due to a $1.4 million increase in fees related to increased investment activity and a $0.9 million increase from the refinancing and prepayment of Investment Portfolio debt investments.

Current wording

(c)The increase in fee income was primarily due to increases of (i) $2.6 million related to increased investment activity and (ii) $1.0 million from increased refinancing and prepayment of Investment Portfolio debt investments.

Previous wording

(d)The increase in total investment income includes a net increase of $2.1 million in certain income considered less consistent or non-recurring, including (i) a $0.9 million increase in such fee income, (ii) a $0.6 million increase in such dividend income and (iii) a $0.6 million increase in such interest income from accelerated prepayment, repricing and other activity related to certain Investment Portfolio debt investments.

Current wording

(d)The increase in total investment income includes a net increase of $1.7 million in certain income considered less consistent or non-recurring, including increases of (i) $1.0 million in such fee income and (ii) $0.7 million in such dividend income.

Previous wording

Total expenses for the three months ended September 30, 2025 were $50.3 million, a 2% increase from the $49.2 million in the corresponding period of 2024. The following table provides a summary of the changes in the comparable period activity.

Current wording

Total expenses for the three months ended March 31, 2026 were $52.3 million, an 11% increase from the $47.2 million in the corresponding period of 2025. A summary of the changes in the comparable period activity is as follows:

Previous wording

(a)The increase in cash compensation was primarily attributable to (i) increased incentive compensation accruals, (ii) increased base compensation rates and (iii) increased headcount to support our growing Investment Portfolio and asset management activities.

Current wording

(a)The increase in cash compensation was primarily attributable to increases in base compensation rates and other compensation related accruals.

Previous wording

(c)The increase in interest expense was primarily related to (i) an increase in average borrowings outstanding used to fund a portion of the growth of our Investment Portfolio and (ii) an increased weighted-average interest rate on our debt obligations resulting from the issuance of the March 2029 Notes and the June 2027 Notes and the repayment at maturity of the May 2024 Notes (each as defined in the Liquidity and Capital Resources section below), partially offset by a decreased weighted-average interest rate on our Credit Facilities due to decreases in benchmark index interest rates and a decrease to the applicable margin rates resulting from the amendments of our Credit Facilities in April 2025.

Current wording

(b)The increase in interest expense was primarily related to an increase in our average borrowings outstanding used to fund a portion of the growth of our Investment Portfolio, partially offset by (i) decreased weighted-average interest rates on our Credit Facilities (as defined in the Liquidity and Capital Resources section below) due to decreases in benchmark floating index interest rates and decreases to the applicable margin rates resulting from the amendments of our Credit Facilities in April 2025 and (ii) a decreased weighted-average interest rate on our unsecured debt obligations resulting from the repayment of the December 2025 Notes and the issuance of the August 2028 Notes (each as defined in the Liquidity and Capital Resources section below).

Previous wording

Net investment income for the three months ended September 30, 2025 increased 3% to $86.5 million, or $0.97 per share, compared to net investment income of $84.4 million, or $0.96 per share, in the corresponding period of 2024. The increase in net investment income is the result of the total investment income increase, partially offset by the total expenses increase, each as discussed above. The increase in net investment income per share reflects the increase in net investment income after the impact of the increase in weighted-average shares outstanding for the three months ended September 30, 2025, primarily due to shares issued since the beginning of the comparable period of the prior year through our (i) at-the-market program (“ATM Program”), (ii) dividend reinvestment and direct stock purchase plan (“DRIP”) and (iii) equity incentive plans. The increase in net investment income on a per share basis also includes a $0.02 per share increase in investment income considered less consistent or non-recurring in nature.

Current wording

Net investment income for the three months ended March 31, 2026 decreased 2% to $84.6 million, or $0.93 per share, compared to $85.9 million, or $0.97 per share, in the corresponding period of 2025. The decrease in net investment income is the result of the increase in the total expenses, partially offset by (i) the increase in total investment income, each as discussed above and (ii) the decrease in net investment income related tax expenses, as discussed below. The decrease in net investment income per share reflects the decrease in net investment income after the impact of the increase in weighted-average shares outstanding for the three months ended March 31, 2026, primarily due to shares issued since the beginning of the comparable period of the prior year through our (i) at-the-market offering program (the “ATM Program”), (ii) dividend reinvestment plan (“DRIP”) and (iii) equity incentive compensation plans. The decrease in net investment income on a per share basis is after a net increase of $0.01 per share resulting from items considered less consistent or non-recurring in nature, including a $0.02 per share increase in such investment income, partially offset by a $0.01 per share increase in deferred compensation expenses.