Annual report [Section 13 and 15(d), not S-K Item 405]

FAIR VALUE HIERARCHY FOR INVESTMENTS???PORTFOLIO COMPOSITION (Tables)

v3.25.4
FAIR VALUE HIERARCHY FOR INVESTMENTS—PORTFOLIO COMPOSITION (Tables)
 12 Months Ended
Dec. 31, 2025
Fair Value Disclosures [Abstract]  
Schedule of Fair Value Measurement Inputs and Valuation Techniques
A summary of the significant unobservable inputs used in the fair value measurement of Main Street’s Level 3 portfolio investments as of December 31, 2025 and 2024 is as follows:
Type of
Investment
Fair Value as of December 31, 2025 (in thousands)
 Valuation Technique Significant Unobservable Inputs Range (4) Weighted-Average (4)(5) Median (4)
Equity investments $ 1,889,374  Discounted cash flow WACC
9.4% - 22.7%
 14.4% 15.0%
Market comparable / Enterprise value EBITDA multiple (1) (3)
5.0x - 9.0x (2)
 7.3x 6.5x
Debt investments $ 3,596,989  Discounted cash flow Risk adjusted discount rate (6)
8.0% - 18.3% (2)
 11.7% 11.5%
Expected principal recovery percentage
0.0% - 500.0%
 99.5% 100.0%
Debt investments $ 10,342  Market approach Third-party quote
14.5 - 63.0
 52.2 40.8
Total Level 3 investments $ 5,496,705 
___________________________
(1)EBITDA may include pro forma adjustments and/or other add-backs based on specific circumstances related to each investment.
(2)Range excludes outliers that are greater than one standard deviation from the mean. Including these outliers, the range for EBITDA multiple is 1.2x - 16.0x and the range for risk adjusted discount rate is 5.4% - 40.4%.
(3)The fair value of the equity investment in the External Investment Manager is based on a fee multiple of 7.8x. The fair value determination is based on a discounted, blended multiple based on the multiples for similar businesses in active markets and actual multiples used in private transactions.
(4)Does not include investments for which the valuation technique does not include the use of the applicable fair value input.
(5)Weighted-average is calculated for each significant unobservable input based on the applicable security’s fair value.
(6)Discount rate includes the effect of the standard SOFR base rate, as applicable.
Type of Investment
Fair Value as of December 31, 2024 (in thousands)
 Valuation Technique
Significant Unobservable Inputs
 Range (4)
Weighted-Average (4)(5)
 Median (4)
Equity investments $ 1,654,304  Discounted cash flow WACC
9.4% - 22.5%
 14.5% 15.1%
Market comparable / Enterprise value EBITDA multiple (1) (3)
4.8x - 8.9x (2)
 7.0x 6.5x
Debt investments $ 3,174,745  Discounted cash flow Risk adjusted discount rate (6)
8.5% - 19.1% (2)
 12.6% 12.2%
Expected principal recovery percentage
0.0% - 100.0%
 99.5% 100.0%
Debt investments $ 103,620  Market approach Third-party quote
21.0 - 100.7
 90.5 84.5
Total Level 3 investments $ 4,932,669 
___________________________
(1)EBITDA may include pro forma adjustments and/or other add-backs based on specific circumstances related to each investment.
(2)Range excludes outliers that are greater than one standard deviation from the mean. Including these outliers, the range for EBITDA multiple is 2.0x - 17.0x and the range for risk adjusted discount rate is 5.0% - 38.3%.
(3)The fair value of the equity investment in the External Investment Manager is based on a fee multiple of 8.5x. The fair value determination is based on a discounted, blended multiple based on the multiples for similar businesses in active markets and actual multiples used in private transactions.
(4)Does not include investments for which the valuation technique does not include the use of the applicable fair value input.
(5)Weighted-average is calculated for each significant unobservable input based on the applicable security’s fair value.
(6)Discount rate includes the effect of the standard SOFR base rate, as applicable.
Schedule of Changes in Fair Value of Main Street’s Level 3 Portfolio Investments
A summary of changes in the fair value of Main Street’s Level 3 portfolio investments for the years ended December 31, 2025 and 2024 is as follows (in thousands):
Type of Investment
Fair Value as of December 31, 2024
 Transfers Out of Level 3 Hierarchy Redemptions/ Repayments New Investments Net Changes from Unrealized to Realized Net Unrealized Appreciation (Depreciation) Other (1)
Fair Value as of December 31, 2025
Debt $ 3,278,365  $ —  $ (907,682) $ 1,265,274  $ 67,307  $ (41,643) $ (54,290) $ 3,607,331 
Equity 1,637,181  (16,810) (61,355) 183,497  (130,407) 191,809  54,290  1,858,205 
Equity Warrant 17,123  —  (600) —  600  14,046  —  31,169 
$ 4,932,669  $ (16,810) $ (969,637) $ 1,448,771  $ (62,500) $ 164,212  $ —  $ 5,496,705 
___________________________
(1)Includes the impact of non-cash conversions. These transactions represent non-cash investing activities. See additional cash flow information in the Consolidated Statements of Cash Flows.
Type of Investment
Fair Value as of December 31, 2023
 Transfers Into Level 3 Hierarchy Redemptions/ Repayments New Investments Net Changes from Unrealized to Realized Net Unrealized Appreciation (Depreciation) Other (1)
Fair Value as of December 31, 2024
Debt $ 2,883,917  $ —  $ (919,626) $ 1,368,567  $ 15,815  $ (58,807) $ (11,501) $ 3,278,365 
Equity 1,395,744  —  (75,972) 133,870  (66,994) 239,032  11,501  1,637,181 
Equity Warrant 6,610  —  —  4,514  (110) 6,109  —  17,123 
$ 4,286,271  $ —  $ (995,598) $ 1,506,951  $ (51,289) $ 186,334  $ —  $ 4,932,669 
___________________________
(1)Includes the impact of non-cash conversions. These transactions represent non-cash investing activities. See additional cash flow information in the Consolidated Statements of Cash Flows.
Schedule of Portfolio Investments by Level in the Fair Value Hierarchy
As of December 31, 2025 and 2024, Main Street’s investments at fair value were categorized as follows in the fair value hierarchy for ASC 820 purposes:
Fair Value Measurements
(in thousands)
December 31, 2025
 Fair Value Quoted Prices in
Active Markets for
Identical Assets
(Level 1)		 Significant Other
Observable Inputs
(Level 2)		 Significant
Unobservable
Inputs
(Level 3)
LMM portfolio investments $ 3,057,023  $ —  $ —  $ 3,057,023 
Private Loan portfolio investments 1,988,438  —  —  1,988,438 
Middle Market portfolio investments 83,498  —  —  83,498 
Other Portfolio investments 134,138  21,412  —  112,726 
External Investment Manager 255,020  —  —  255,020 
Total investments $ 5,518,117  $ 21,412  $ —  $ 5,496,705 
Fair Value Measurements
(in thousands)
December 31, 2024
 Fair Value Quoted Prices in
Active Markets for
Identical Assets
(Level 1)		 Significant Other
Observable Inputs
(Level 2)		 Significant
Unobservable
Inputs
(Level 3)
LMM portfolio investments $ 2,502,872  $ —  $ —  $ 2,502,872 
Private Loan portfolio investments 1,904,324  —  —  1,904,324 
Middle Market portfolio investments 155,329  —  —  155,329 
Other Portfolio investments 124,144  —  —  124,144 
External Investment Manager 246,000  —  —  246,000 
Total investments $ 4,932,669  $ —  $ —  $ 4,932,669 
Schedule of Investment Holdings
A summary of Main Street’s LMM and Private Loan portfolio investments as of December 31, 2025 and 2024 is as follows (this information excludes Middle Market, Other Portfolio investments and the External Investment Manager, which are discussed further below):
December 31, 2025
LMM (a) Private Loan
(dollars in millions)
Number of portfolio companies 92  86 
Fair value $ 3,057.0  $ 1,988.4 
Cost $ 2,419.3  $ 2,014.1 
Debt investments as a % of portfolio (at cost) 71.2  % 93.5  %
Equity investments as a % of portfolio (at cost) 28.8  % 6.5  %
% of debt investments at cost secured by first priority lien 99.4  % 99.9  %
Weighted-average annual effective yield (b) 12.5  % 10.5  %
Average EBITDA (c) $ 11.1  $ 33.9 
___________________________
(a)As of December 31, 2025, Main Street had equity ownership in all of its LMM portfolio companies, and the average fully diluted equity ownership in those portfolio companies was 37%.
(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 Main Street’s debt portfolio as of December 31, 2025, including debt investments on non-accrual status, was 12.0% for its LMM portfolio investments and 10.1% for its Private Loan portfolio investments. The weighted-average annual effective yield is not reflective of what an investor in shares of Main Street’s common stock will realize on its investment because it does not reflect changes in the market value of Main Street’s stock, Main Street’s utilization of debt capital in its capital structure, Main Street’s expenses or any sales load paid by an investor.
(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 Main Street’s 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.
December 31, 2024
LMM (a) Private Loan
(dollars in millions)
Number of portfolio companies 84  91 
Fair value $ 2,502.9  $ 1,904.3 
Cost $ 1,937.8  $ 1,952.5 
Debt investments as a % of portfolio (at cost) 70.8  % 95.4  %
Equity investments as a % of portfolio (at cost) 29.2  % 4.6  %
% of debt investments at cost secured by first priority lien 99.2  % 99.9  %
Weighted-average annual effective yield (b) 12.8  % 11.8  %
Average EBITDA (c) $ 10.2  $ 30.5 
___________________________
(a)As of December 31, 2024, Main Street had equity ownership in all of its LMM portfolio companies, and the average fully diluted equity ownership in those portfolio companies was 38%.
(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 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, 2024. The weighted-average annual effective yield on Main Street’s debt portfolio as of December 31, 2024, including debt investments on non-accrual status, was 12.3% for its LMM portfolio investments and 11.5% for its Private Loan portfolio investments. The weighted-average annual effective yield is not reflective of what an investor in shares of Main Street’s common stock will realize on its investment because it does not reflect changes in the market value of Main Street’s stock, Main Street’s utilization of debt capital in its capital structure, Main Street’s expenses or any sales load paid by an investor.
(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 five Private Loan portfolio companies, as EBITDA is not a meaningful valuation metric for Main Street’s 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.
The composition of Main Street’s 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 December 31, 2025 and 2024, is as follows (this information excludes Other Portfolio investments and the External Investment Manager, which are discussed above):
Cost: December 31, 2025 December 31, 2024
First lien debt 80.9  % 82.9  %
Equity 18.6  16.4 
Second lien debt 0.1  0.2 
Equity warrants 0.2  0.3 
Other 0.2  0.2 
100.0  % 100.0  %
Fair Value: December 31, 2025 December 31, 2024
First lien debt 69.8  % 71.4  %
Equity 29.4  27.8 
Second lien debt —  0.2 
Equity warrants 0.6  0.4 
Other 0.2  0.2 
100.0  % 100.0  %
Main Street’s LMM, Private Loan and Middle Market portfolio companies are located primarily in the U.S. The geographic composition is determined by the location of the corporate headquarters of the portfolio company. The composition of Main Street’s total combined LMM, Private Loan and Middle Market portfolio investments by geographic region of the U.S. and other countries at cost and fair value as a percentage of the total combined LMM, Private Loan and Middle Market portfolio investments, as of December 31, 2025 and 2024, is as follows (this information excludes Other Portfolio investments and the External Investment Manager):
Cost: December 31, 2025 December 31, 2024
West 25.3  % 25.1  %
Midwest 19.2  22.7 
Southwest 19.0  16.7 
Southeast 17.5  11.6 
Northeast 15.4  21.2 
Canada 2.2  1.3 
Other Non-U.S. 1.4  1.4 
100.0  % 100.0  %
Fair Value: December 31, 2025 December 31, 2024
West 24.8  % 24.1  %
Southwest 23.0  20.1 
Midwest 20.1  24.2 
Southeast 15.8  9.7 
Northeast 13.1  19.4 
Canada 1.9  1.2 
Other Non-U.S. 1.3  1.3 
100.0  % 100.0  %
Main Street’s LMM, Private Loan and Middle Market portfolio investments are in companies conducting business in a variety of industries. The composition of Main Street’s total combined LMM, Private Loan and Middle Market portfolio investments by industry at cost and fair value, as of December 31, 2025 and 2024, is as follows (this information excludes Other Portfolio investments and the External Investment Manager):
Cost: December 31, 2025 December 31, 2024
Machinery 8.3  % 9.2  %
Commercial Services & Supplies 6.8  5.5 
Construction & Engineering 6.1  3.8 
Electrical Equipment 5.9  3.9 
Professional Services 5.3  5.4 
Distributors 5.0  4.0 
Diversified Consumer Services 4.7  4.3 
Health Care Providers & Services 4.2  4.3 
Internet Software & Services 4.2  7.1 
IT Services 3.7  4.1 
Containers & Packaging 3.3  3.8 
Auto Components 3.2  4.0 
Textiles, Apparel & Luxury Goods 2.5  2.8 
Tobacco 2.5  2.8 
Energy Equipment & Services 2.4  2.8 
Aerospace & Defense 2.3  1.6 
Leisure Equipment & Products 2.1  2.4 
Software 2.1  2.2 
Computers & Peripherals 2.0  2.8 
Specialty Retail 2.0  2.0 
Communications Equipment 1.9  2.1 
Trading Companies & Distributors 1.8  0.8 
Media 1.6  1.7 
Air Freight & Logistics 1.5  0.5 
Chemicals 1.4  1.3 
Food & Staples Retailing 1.4  1.6 
Food Products 1.4  1.6 
Beverages 1.2  — 
Hotels, Restaurants & Leisure 1.1  1.3 
Oil, Gas & Consumable Fuels 1.1  — 
Internet & Catalog Retail 1.0  1.1 
Health Care Equipment & Supplies 0.8  1.1 
Diversified Financial Services 0.7  1.4 
Building Products 0.4  1.5 
Other (1) 4.1  5.2 
100.0  % 100.0  %
___________________________
(1)Includes various industries with each industry individually less than 1.0% of the total combined LMM, Private Loan and Middle Market portfolio investments at each date.
Fair Value: December 31, 2025 December 31, 2024
Machinery 10.2  % 11.0  %
Construction & Engineering 6.5  4.3 
Diversified Consumer Services 6.1  6.0 
Commercial Services & Supplies 5.9  4.8 
Electrical Equipment 5.9  3.7 
Distributors 5.5  4.2 
Professional Services 5.2  5.2 
Health Care Providers & Services 3.8  4.5 
IT Services 3.8  3.7 
Computers & Peripherals 3.6  4.6 
Containers & Packaging 3.4  3.8 
Internet Software & Services 3.4  5.9 
Auto Components 3.0  3.6 
Tobacco 2.6  2.9 
Energy Equipment & Services 2.5  2.9 
Specialty Retail 2.4  2.5 
Software 2.2  2.3 
Aerospace & Defense 2.0  1.6 
Textiles, Apparel & Luxury Goods 1.9  1.9 
Communications Equipment 1.7  1.4 
Media 1.6  1.9 
Trading Companies & Distributors 1.6  0.7 
Leisure Equipment & Products 1.4  1.7 
Air Freight & Logistics 1.3  0.9 
Chemicals 1.3  1.2 
Beverages 1.1  — 
Food & Staples Retailing 1.1  1.2 
Food Products 1.1  1.5 
Oil, Gas & Consumable Fuels 1.0  — 
Diversified Financial Services 0.7  1.3 
Internet & Catalog Retail 0.7  1.0 
Building Products 0.5  1.4 
Other (1) 5.0  6.4 
100.0  % 100.0  %
___________________________
(1)Includes various industries with each industry individually less than 1.0% of the total combined LMM, Private Loan and Middle Market portfolio investments at each date.