Main Street Capital CORP

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) 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 (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).

Previous wording

MSC Adviser I, LLC (the “External Investment Manager”) was formed in November 2013 as a wholly-owned subsidiary of Main Street to provide investment management and other services to parties other than Main Street (“External Parties”) and earns 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 Main Street and is not included as a consolidated subsidiary in Main Street’s consolidated financial statements.

Current wording

MSC Adviser I, LLC (the “External Investment Manager”) was formed in November 2013 as a wholly-owned subsidiary of Main Street to provide investment management and other services to parties other than Main Street (“External Parties”) and earns fee income for such services. MSCC has been granted no-action relief by the 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 Main Street and is not included as a consolidated subsidiary in Main Street’s consolidated financial statements.

Previous wording

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 participation. 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. We believe that providing customized, “one-stop” financing solutions is important and valuable to LMM portfolio companies. We generally seek to partner directly with entrepreneurs, management teams and business owners in making our LMM 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.

Current wording

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 participation. 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. We believe that providing customized, “one-stop” financing solutions is important and valuable to LMM portfolio companies. We generally seek to partner directly with entrepreneurs, management teams and business owners in making our LMM investments. Our LMM portfolio debt investments are generally secured by a first priority lien on the assets of the portfolio company and typically have a term of between five and seven years from the original investment date.

Previous wording

We also maintain a legacy portfolio of investments in larger Middle Market companies. Our Middle Market investments are generally debt investments in companies owned by private equity funds that were originally issued through a syndication financing process. We have generally stopped making new Middle Market investments and expect the size of our Middle Market investment portfolio to continue to decline in future periods as existing Middle Market investments are repaid or sold. Our Middle Market debt investments generally range in size from $3 million to $25 million, are generally secured by a first 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.

Current wording

We also maintain a legacy portfolio of investments in larger Middle Market companies. Our Middle Market investments are generally debt investments in companies owned by a private equity fund that were originally issued through a syndication financing process. We have generally stopped making new Middle Market investments and expect the size of our Middle Market investment portfolio to continue to decline in future periods as existing Middle Market investments are repaid or sold. Our Middle Market debt investments generally range in size from $3 million to $25 million, are generally secured by a first 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.

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 June 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 3.6% for the trailing twelve months ended June 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 is described in greater detail in Note F — Financial Highlights 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 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.

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 June 30, 2025 and 2024, the External Investment Manager earned $5.7 million and $5.9 million in base management fees, respectively, $3.7 million and $4.1 million in incentive fees, respectively, and $0.2 million of administrative service fee income for each of the three months ended June 30, 2025 and 2024. For the six months ended June 30, 2025 and 2024, the External Investment Manager earned $11.5 million and $11.6 million in base management fees, respectively, $6.4 million and $8.0 million in incentive fees, respectively, and $0.3 million of administrative service fee income for each of the six months ended June 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 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.

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 each of the three months ended June 30, 2025 and 2024 are net of expenses allocated to the External Investment Manager of $5.9 million. Our total expenses for the six months ended June 30, 2025 and 2024 are net of expenses allocated to the External Investment Manager of $11.2 million and $11.4 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 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.

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 June 30, 2025 and 2024, dividends accrued by us from the External Investment Manager were $2.8 million and $3.3 million, respectively. For the three months ended June 30, 2025 and 2024, the total contribution of the External Investment Manager to our net investment income was $8.7 million and $9.2 million, respectively. For the six months ended June 30, 2025 and 2024, dividends accrued by us from the External Investment Manager were $5.3 million and $6.3 million, respectively. For the six months ended June 30, 2025 and 2024, the total contribution of the External Investment Manager to our net investment income was $16.6 million and $17.8 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 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.

Previous wording

(b)The weighted-average annual effective yields were computed using the effective interest rates for all debt investments as of June 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 June 30, 2025. The weighted-average annual effective yield on our debt portfolio as of June 30, 2025, including debt investments on non-accrual status, was 12.1% for our LMM portfolio and 10.0% 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 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.

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 six 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 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.

Previous wording

For the three months ended June 30, 2025 and 2024, we achieved an annualized total return on investments of 16.4% and 15.7%, respectively. For each of the six months ended June 30, 2025 and 2024, we achieved an annualized total return on investments of 16.2%. 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 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.

Previous wording

As of June 30, 2025, we had Other Portfolio investments in 32 entities, spread across 12 investment managers, collectively totaling $122.7 million in fair value and $126.0 million in cost basis, which comprised 2.4% and 2.9% 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 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.

Previous wording

As of June 30, 2025, we had Middle Market portfolio investments in 12 portfolio companies, collectively totaling $108.7 million in fair value and $134.2 million in cost basis, which comprised 2.1% and 3.1% 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 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.

Previous wording

As previously discussed in Note A.1. — Organization and Basis of Presentation — Organization, we hold an investment in the External Investment Manager, a wholly-owned subsidiary that is treated as a portfolio investment. As of June 30, 2025, this investment had a fair value of $272.6 million and a cost basis of $29.5 million, which comprised 5.4% 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 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.

Previous wording

Management has discussed the development and selection of each critical accounting policy and estimate with the Audit Committee of the Board of Directors. Our critical accounting policies and estimates include the Investment Portfolio Valuation and Revenue Recognition policies described below. Our significant accounting policies are described in greater detail in Note B — Summary of Significant Accounting Policies to the consolidated financial statements included in Item 1. Consolidated Financial Statements of this Quarterly Report on Form 10-Q.

Current wording

Management has discussed the development and selection of each critical accounting policy and estimate with the Audit Committee of the Board of Directors. Our critical accounting policies and estimates include the Investment Portfolio Valuation and Revenue Recognition policies described below. Our significant accounting policies are described in greater detail in Note B — Summary of Significant Accounting Policies 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 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 June 30, 2025 and December 31, 2024, our Investment Portfolio valued at fair value represented 96% 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 Portfolio 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 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.

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 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 June 30, 2025 and 2024, (i) 2.3% and 3.7%, respectively, of our total investment income was attributable to PIK interest income not paid currently in cash and (ii) 0.9% and 0.5%, respectively, of our total investment income was attributable to cumulative dividend income not paid currently in cash. For the six months ended June 30, 2025 and 2024, 2.6% and 3.5%, respectively, of our total investment income was attributable to PIK interest income not paid currently in cash. For the six months ended June 30, 2025 and 2024, 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 (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.

Previous wording

As of June 30, 2025, investments on non-accrual status comprised 2.1% of our total Investment Portfolio at fair value and 5.0% 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 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.

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, for the three months ended June 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 for details.

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 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.

Previous wording

(a)Distributable net investment income is net investment income as determined in accordance with U.S. GAAP, excluding the impacts 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 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.

Previous wording

Total investment income for the three months ended June 30, 2025 was $144.0 million, a 9% increase from the $132.2 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 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.

Previous wording

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

Current wording

(a)The decrease in interest income was principally attributable to (i) 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 and (ii) an increase in investments on non-accrual status, partially offset by higher average levels of income producing Investment Portfolio debt investments.

Previous wording

(b)The increase in dividend income was primarily a result of (i) an increase of $24.6 million in dividend income from our LMM portfolio companies and (ii) an increase $1.8 million in dividend income from our Private Loan portfolio companies, partially offset by (i) a decrease of $1.0 million in dividend income from our External Investment Manager and (ii) a decrease of $0.9 million in dividend income from our Other Portfolio investments.

Current wording

(b)The increase in dividend income was primarily a result of dividend income increases of (i) $6.6 million from our LMM portfolio companies, (ii) $0.7 million from our Other Portfolio investments and (iii) $0.5 million from our External Investment Manager.

Previous wording

(d)The increase in total investment income includes a net decrease of $2.1 million in certain income considered less consistent or non-recurring, including a $4.2 million decrease in such fee income, partially offset by (i) a $1.9 million increase in such dividend income and (ii) a $0.2 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 $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.

Previous wording

Total expenses for the three months ended June 30, 2025 were $50.6 million, a 13% increase from the $44.9 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 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.

Previous wording

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

Current 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.

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 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 decrease in the weighted-average interest rate on our Credit Facilities (as defined in the Liquidity and Capital Resources section below) resulting from decreases in the benchmark index interest rates and decreases to the applicable margin rates related to the amendments of our Credit Facilities in April 2025.

Current wording

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

Previous wording

Net investment income for the three months ended June 30, 2025 increased 5% to $88.2 million, or $0.99 per share, compared to net investment income of $83.9 million, or $0.97 per share, in the corresponding period of 2024. The increase in net investment income per share reflects the impact of the increase in weighted-average shares outstanding for the three months ended June 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 plan and (iii) equity incentive plans. The increase in net investment income on a per share basis also includes a $0.02 per share increase from items considered less consistent or non-recurring in nature, including a $0.03 per share increase in investment income and a $0.01 per share increase in deferred compensation expense.

Current 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.

Previous wording

Distributable net investment income for the three months ended June 30, 2025 increased 6% to $94.3 million, or $1.06 per share, compared to $88.9 million, or $1.03 per share, in the corresponding period of 2024. The increase in distributable net investment income was primarily due to (i) the increase in net investment income as discussed above, (ii) an increase in deferred compensation expense and (iii) an increase in share-based compensation expense. The increase in distributable net investment income per share reflects the impact of the increase in weighted-average shares outstanding for the three months ended June 30, 2025, as discussed above. The increase in distributable net investment income on a per share basis also includes a $0.03 per share increase in investment income considered less consistent or non-recurring in nature.

Current wording

Distributable net investment income for the three months ended September 30, 2025 increased 3% to $92.7 million, or $1.03 per share, compared to $89.8 million, or $1.03 per share, in the corresponding period of 2024. The increase in distributable net investment income was primarily due to (i) the increase in net investment income as discussed above and (ii) an increase in share-based compensation expense. The increase in distributable net investment income per share reflects the impact of the increase in weighted-average shares outstanding for the three months ended September 30, 2025, as discussed above. Distributable 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.

Previous wording

The following table provides a summary of the primary components of the total net realized gain on investments of $52.4 million for the three months ended June 30, 2025.

Current wording

The following table provides a summary of the primary components of the total net realized loss on investments of $19.1 million for the three months ended September 30, 2025.

Previous wording

The following table provides a summary of the total net unrealized appreciation of $44.2 million for the six months ended June 30, 2025:

Current wording

The following table provides a summary of the total net unrealized appreciation of $63.0 million for the three months ended September 30, 2025.

Previous wording

(a)Includes unrealized appreciation on 36 LMM portfolio investments and unrealized depreciation on 26 LMM portfolio investments.

Current wording

(a)Includes unrealized appreciation on 42 LMM portfolio investments and unrealized depreciation on 17 LMM portfolio investments.

Previous wording

Main Street’s income taxes include excise tax expense at MSCC and federal and state income and other tax expenses at the Taxable Subsidiaries. MSCC has elected to be treated for U.S. federal income tax purposes as a RIC. MSCC’s taxable income includes the taxable income generated by MSCC and certain of its subsidiaries, including the Funds and Structured Subsidiaries, which are treated as disregarded entities for tax purposes. As a result of its investment activities and dividend policy and activities, MSCC incurs federal excise tax on its estimated undistributed taxable income. The Taxable Subsidiaries incur federal and state income and other taxes related to net investment income resulting from the Taxable Subsidiaries’ investment activities. The excise tax expense increase is due to changes in our estimated undistributed taxable income at the RIC, which is taxed at a 4% rate. The net investment income related federal and state income and other tax expenses increase is due to increases in taxable net investment income at the Taxable Subsidiaries.

Current wording

Main Street’s income taxes include excise tax expense at MSCC and federal and state income and other tax expenses at the Taxable Subsidiaries. MSCC has elected to be treated for U.S. federal income tax purposes as a RIC. MSCC’s taxable income includes the taxable income generated by MSCC and certain of its subsidiaries, including the Funds and Structured Subsidiaries, which are treated as disregarded entities for tax purposes. As a result of its investment activities and dividend policy and activities, MSCC incurs federal excise tax on its estimated undistributed taxable income. The Taxable Subsidiaries incur federal and state income and other taxes related to net investment income resulting from the Taxable Subsidiaries’ investment activities. The excise tax expense increase is due to changes in our estimated undistributed taxable income at the RIC, which is taxed at a 4% rate. The net investment income related federal and state income and other tax expenses decrease is due to decreases in taxable net investment income at the Taxable Subsidiaries.

Previous wording

The Taxable Subsidiaries also incur taxes on realized gains (losses) and unrealized appreciation (depreciation). These taxes will change over time due to changes in the valuations of our portfolio investments and due to realized gains and losses on our investments owned by the Taxable Subsidiaries.

Current wording

The Taxable Subsidiaries also incur taxes on realized gains (losses) and unrealized appreciation (depreciation). These taxes will change over time due to changes in the valuations of portfolio investments and realized gains and losses, in each case, on our investments owned by the Taxable Subsidiaries.

Previous wording

The net increase in net assets resulting from operations for the three months ended June 30, 2025 was $122.5 million, or $1.37 per share, compared to $102.7 million, or $1.19 per share, during the three months ended June 30, 2024. The tables above provide a summary of the reasons for the change in net increase in net assets resulting from operations for the three months ended June 30, 2025 as compared to the three months ended June 30, 2024.

Current wording

The net increase in net assets resulting from operations for the three months ended September 30, 2025 was $123.7 million, or $1.38 per share, compared to $124.0 million, or $1.42 per share, during the three months ended September 30, 2024. The tables above provide a summary of the reasons for the change in net increase in net assets resulting from operations for the three months ended September 30, 2025 as compared to the three months ended September 30, 2024.

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, for the six months ended June 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 for details.

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 distributable net investment income before taxes, for the nine 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.

Previous wording

Total investment income for the six months ended June 30, 2025 was $281.0 million, a 7% increase from the $263.8 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 nine months ended September 30, 2025 was $420.9 million, a 5% increase from the $400.6 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.

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 on floating rate Investment Portfolio debt investments primarily resulting from decreases in benchmark index rates, partially offset by higher average levels of income producing Investment Portfolio debt investments.

Current 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.

Previous wording

(b)The increase in dividend income was primarily a result of (i) an increase of $11.5 million in dividend income from our LMM portfolio companies and (ii) an increase of $0.6 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 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.

Previous wording

(c)The decrease in fee income was primarily related to (i) a $4.0 million decrease from lower exit, prepayment and amendment activity and (ii) a $1.9 million decrease in fees related to decreased investment activity.

Current wording

(c)The decrease in fee income was primarily related to (i) a $3.1 million decrease from lower exit, prepayment and amendment activity and (ii) a $0.5 million decrease in fees related to decreased investment activity.