Our principal investment objective is to maximize our Investment Portfolio’s total return, primarily by generating current income from our debt investments and, to a lesser extent, by generating current income and capital appreciation from our equity and equity-related investments, including warrants, convertible securities and other rights to acquire equity securities in a portfolio company. We seek to achieve our investment objective primarily through our Private Loan investment strategy and our LMM investment portfolio. Our Private Loan investment strategy involves investments in companies that generally have annual revenues between $25 million and $500 million and annual earnings before interest, tax, depreciation and amortization expenses (“EBITDA”) between $7.5 million and $50 million. Our LMM investment portfolio consists of investments in companies that generally have annual revenues between $10 million and $150 million and annual EBITDA between $3 million and $20 million. Our Private Loan and LMM investments generally range in size from $1 million to $30 million.

Private Loan investments primarily consist of debt securities that have primarily been originated directly by our Adviser or, to a lesser extent, through our Adviser’s strategic relationships with other investment funds on a collaborative basis through investments that are often referred to in the debt markets as “club deals” because of the small lender group size. In both cases, our Private Loan investments are typically made in a company owned by or in the process of being acquired by a private equity fund. Our Private Loan 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 three and seven years from the original investment date. We may also co-invest with Main Street and the private equity funds in the equity securities of our Private Loan portfolio companies.

We have also historically sought 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 created 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, allowed us to offer portfolio companies a comprehensive suite of financing options, or a “one-stop” financing solutions. 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.

In connection with the MSC Income Listing, our Board of Directors and the Adviser decided to change our investment strategy with respect to new platform investments to be solely focused on our Private Loan investment strategy. As a result, the size of our LMM investment portfolio is expected to decrease over time as our existing LMM investments are repaid or sold in the ordinary course of business. We do, however, plan to continue executing follow-on investments in our existing LMM portfolio companies going forward in accordance with our existing SEC order for co-investment exemptive relief.

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 $1 million to $20 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.

Our Other Portfolio investments primarily consist of investments that are not consistent with the typical profiles for our Private Loan, LMM or Middle Market portfolio investments, including investments in unaffiliated investment companies and private funds managed by third parties. In our Other Portfolio, we may incur indirect fees and expenses to third party managers. Similar to our Middle Market investments, we have generally stopped making new Other Portfolio investments and expect the size of our Other Portfolio to continue to decline in future periods as existing Other Portfolio investments are repaid or sold.

Subject to changes in our cash and overall liquidity, we may in the future invest in short-term portfolio investments that are atypical of our Private Loan and LMM portfolio investments in that they would be intended to be a short-term deployment of capital. These assets would be expected to be realized in one year or less and would not be expected to be a significant portion of our total investments.

Our portfolio investments are generally made through MSIF, the Taxable Subsidiaries and the Structured Subsidiaries. MSIF, the Taxable Subsidiaries and the Structured Subsidiaries share the same investment strategies and

criteria. An investor’s return in MSIF will depend, in part, on the Taxable Subsidiaries’ and the Structured Subsidiaries’ investment returns as they are wholly-owned subsidiaries of MSIF.

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

We have received an exemptive order from the SEC permitting co-investments among us, Main Street and other advisory clients of our Adviser 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 Main Street and other advisory clients of our Adviser, in accordance with the conditions of the order. The order requires, among other things, that Main Street and our Adviser consider whether each such investment opportunity is appropriate for us, Main Street and the other advisory clients of our Adviser, as applicable, and if it is appropriate, to propose an allocation of the investment opportunity between such parties. Because our Adviser is wholly-owned by Main Street and is not managing our investment activities as its sole activity, this may provide our Adviser an incentive to allocate opportunities to Main Street or its other advisory clients instead of us. However, both we and our Adviser 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 syndicated deals and other transactions where price is the only negotiated point by us and our affiliates.

Risk Factors [Table Text Block]

You should carefully consider the risks described below and all other information contained in this Quarterly Report on Form 10-Q, including our interim consolidated financial statements and the related notes thereto, before making a decision to purchase our securities. The risks and uncertainties described below are not the only ones facing us. Additional risks and uncertainties not currently known to us or that we currently deem to be immaterial also may have a material adverse effect on our business, financial condition and/or operating results, as well as the market price of our securities.

In addition to the other information set forth in this report, you should carefully consider the risk factors described in Item 1A. Risk Factors in our Annual Report on Form 10-K for the fiscal year ended December 31, 2024 that we filed with the SEC on March 20, 2025, which could materially affect our business, financial condition and/or operating results.

NAV Per Share

$ 15.35

$ 15.53

$ 15.44

$ 15.54

Corporate Facility [Member]

Capital Stock, Long-Term Debt, and Other Securities [Abstract]

Long Term Debt, Title [Text Block]

Corporate Facility

Long Term Debt, Principal

$ 149,000

Long Term Debt, Structuring [Text Block]

March 31, 2025, the Corporate Facility included (i) total commitments of $245.0 million, (ii) an accordion feature with the right to request an increase in commitments under the facility from new and existing lenders on the same terms and conditions as the existing commitments up to $300.0 million of total commitments and (iii) a revolving period through November 2028 and a final maturity date in May 2029, with two one-year extension options subject to lender approval.

Borrowings under the Corporate Facility bear interest, subject to MSC Income’s election, at a rate equal to (i) SOFR plus 2.05% or (ii) the base rate plus 1.05%. The base rate is defined as the higher of (a) the Prime rate, (b) the Federal Funds Rate (as defined in the credit agreement) plus 0.5% or (c) SOFR plus 1.0%. Additionally, MSC Income pays an unused commitment fee of 0.25% on the unused lender commitments if more than 50% or more of the lender commitments are being used and an annual unused commitment fee of 0.375% on the unused lender commitments if less than 50% of the lender commitments are being used. Borrowings under the Corporate Facility are secured by a first lien on all of the assets of MSIF and its subsidiaries, excluding the assets of Structured Subsidiaries or immaterial subsidiaries, as well as all of the assets, and a pledge of equity ownership interests, of any future subsidiaries of MSIF (other than Structured Subsidiaries or immaterial subsidiaries). In connection with the Corporate Facility, MSIF has made customary representations and warranties and is required to comply with various covenants, reporting requirements and other customary requirements for similar credit facilities. Our borrowing ability is limited to leverage and borrowing base restrictions imposed by the Corporate Facility and the 1940 Act.

SPV Facility [Member]

Capital Stock, Long-Term Debt, and Other Securities [Abstract]

Long Term Debt, Title [Text Block]

SPV Facility

Long Term Debt, Structuring [Text Block]

MSC Income, through MSIF Funding, LLC (“MSIF Funding”), a wholly-owned Structured Subsidiary that primarily holds debt investments, is party to a senior secured revolving credit facility dated February 3, 2021 (as amended, the “SPV Facility”) with JPMorgan Chase Bank, National Association (“JPM”), as administrative agent, and U.S. Bank, N.A., as collateral agent and collateral administrator, JPM and other financial institutions as lenders and MSIF as portfolio manager. In March 2025, the SPV facility was amended to, among other things: (i) decrease the interest rate for advances to the applicable SOFR plus 2.20% from the prior interest rate of the applicable SOFR plus 3.00%, (ii) extend the revolving

period from through February 2027 to through February 2029 and (iii) extend the final maturity date from February 2028 to February 2030.

As of March 31, 2025, the SPV Facility included (i) total commitments of $300.0 million ,(ii) an accordion feature with the right to request an increase of total commitments and borrowing availability up to $450.0 million and (iii) a revolving period through February 2029 and a final maturity date in February 2030. As of March 31, 2025, advances under the SPV Facility bore interest at a rate equal to the applicable SOFR in effect, plus a margin of 2.20%. MSIF Funding also pays a commitment fee of 0.75% on the average daily unused amount of the financing commitments until February 2029. The SPV Facility is secured by a collateral loan on the assets of MSIF Funding. In connection with the SPV Facility, MSIF Funding has made customary representations and warranties and is required to comply with various covenants, reporting requirements and other customary requirements for similar credit facilities. Our borrowing ability is limited to leverage and borrowing base restrictions imposed by the SPV Facility and the 1940 Act.

Series A Notes due 2026 [Member]

Capital Stock, Long-Term Debt, and Other Securities [Abstract]

Long Term Debt, Title [Text Block]

Series A Notes

Long Term Debt, Structuring [Text Block]

Pursuant to a Master Note Purchase Agreement dated October 21, 2021 (the “Note Purchase Agreement”), MSC Income issued $77.5 million of 4.04% Series A Senior Notes due 2026 (the “Series A Notes”) upon entering into the Note Purchase Agreement and an additional $72.5 million on January 21, 2022. The Series A Notes bear a fixed interest rate of 4.04% per year and will mature on October 30, 2026, unless redeemed, purchased or prepaid prior to such date by the Company in accordance with their terms.

Interest on the Series A Notes is due semiannually on April 30 and October 30 of each year. The Series A Notes may be redeemed in whole or in part at any time or from time to time at MSC Income’s option at par plus accrued interest to the prepayment date and, if applicable, a make-whole premium. In addition, MSC Income is obligated to offer to prepay the Series A Notes at par plus accrued and unpaid interest up to, but excluding, the date of prepayment, if certain change in control events occur. In the event that a Below Investment Grade Event (as defined in the Note Purchase Agreement) occurs, the Series A Notes will bear interest at a fixed rate of 5.04% per year from the date of the occurrence of the Below Investment Grade Event to and until the date on which the Below Investment Grade Event ends. The Series A Notes are general unsecured obligations of MSIF that rank pari passu with all outstanding and future unsecured unsubordinated indebtedness issued by MSIF.

The Note Purchase Agreement also contains customary events of default with customary cure and notice periods, including, without limitation, nonpayment, incorrect representation in any material respect, breach of covenant, cross-default under other indebtedness of MSIF or subsidiary guarantors subject to a cure pass-through, certain judgments and orders and certain events of bankruptcy.