FAIR VALUE HIERARCHY FOR INVESTMENTS—PORTFOLIO COMPOSITION (Tables)

6 Months Ended

Jun. 30, 2025

Schedule of Fair Value Measurement Inputs and Valuation Techniques

The following tables provide a summary of the significant unobservable inputs used to fair value Main Street’s Level 3 portfolio investments as of June 30, 2025 and December 31, 2024:


Type of Investment	Fair Value as of June 30, 2025 (in thousands)		Valuation Technique	Significant Unobservable Inputs	Range (4)	Weighted-Average (4)(5)		Median (4)
Equity investments	$	1,744,101	Discounted cash flow	WACC	9.7% - 22.7%	14.5	%	15.1	%
			Market comparable / Enterprise value	EBITDA multiple (1) (3)	5.0x - 9.0x (2)	7.2x		6.5x
Debt investments	$	3,301,875	Discounted cash flow	Risk adjusted discount rate (6)	8.3% - 18.6% (2)	12.3	%	12.1	%
				Expected principal recovery percentage	0.0% - 500.0%	98.8	%	100.0	%
Debt investments	$	25,537	Market approach	Third-party quote	14.5 - 99.7	81.2		55.0
Total Level 3 investments	$	5,071,513

___________________________

(1)EBITDA may include proforma 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 - 16.0x and the range for risk adjusted discount rate is 5.0% - 36.0%.

(3)The fair value of the equity investment in the External Investment Manager is based on a fee multiple of 8.7x. 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 proforma 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

The following tables provide a summary of changes in fair value of Main Street’s Level 3 portfolio investments for the six months ended June 30, 2025 and 2024 (amounts 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 June 30, 2025
Debt	$	3,278,365	$	—	$	(514,216)	$	575,433	$	38,415	$	(19,812)	$	(30,773)	$	3,327,412
Equity	1,637,181		(16,810)		(30,679)		80,309		(65,185)		83,449		30,773		1,719,038
Equity Warrant	17,123		—		—		—		—		7,940		—		25,063
	$	4,932,669	$	(16,810)	$	(544,895)	$	655,742	$	(26,770)	$	71,577	$	—	$	5,071,513

___________________________

(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 June 30, 2024
Debt	$	2,883,917	$	—	$	(406,233)	$	753,750	$	7,468	$	(19,162)	$	18,859	$	3,238,599
Equity	1,395,744		—		(28,445)		65,122		(960)		75,391		(18,859)		1,487,993
Equity Warrant	6,610		—		—		3,920		—		389		—		10,919
	$	4,286,271	$	—	$	(434,678)	$	822,792	$	6,508	$	56,618	$	—	$	4,737,511

___________________________

(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 June 30, 2025 and December 31, 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)
As of June 30, 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	$	2,668,844	$	—	$	—	$	2,668,844
Private Loan portfolio investments	1,920,257		—		—		1,920,257
Middle Market portfolio investments	108,705		—		—		108,705
Other Portfolio investments	122,664		21,557		—		101,107
External Investment Manager	272,600		—		—		272,600

Total investments	$	5,093,070	$	21,557	$	—	$	5,071,513


			Fair Value Measurements
			(in thousands)
As of 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

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


	As of June 30, 2025
	LMM (a)			Private Loan
	(dollars in millions)
Number of portfolio companies	88			87
Fair value	$	2,668.8		$	1,920.3
Cost	$	2,105.0		$	1,958.0
Debt investments as a % of portfolio (at cost)	70.1		%	94.7		%
Equity investments as a % of portfolio (at cost)	29.9		%	5.3		%
% of debt investments at cost secured by first priority lien	99.3		%	99.9		%
Weighted-average annual effective yield (b)	12.8		%	11.4		%
Average EBITDA (c)	$	10.4		$	32.5

___________________________

(a)As of June 30, 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 38%.

(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 Main Street’s debt portfolio as of June 30, 2025, including debt investments on non-accrual status, was 12.1% for its LMM portfolio and 10.0% for its Private Loan portfolio. 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 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 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.


	As of 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 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 Main Street’s debt portfolio as of December 31, 2024, including debt investments on non-accrual status, was 12.3% for its LMM portfolio and 11.5% for its Private Loan portfolio. 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 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 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 following tables summarize 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 June 30, 2025 and December 31, 2024 (this information excludes Other Portfolio investments and the External Investment Manager, which are discussed above).


Cost:	June 30, 2025		December 31, 2024
First lien debt	81.5	%	82.9	%
Equity	17.9		16.4
Second lien debt	0.1		0.2
Equity warrants	0.3		0.3
Other	0.2		0.2
	100.0	%	100.0	%


Fair Value:	June 30, 2025		December 31, 2024
First lien debt	70.5	%	71.4	%
Equity	28.7		27.8
Second lien debt	0.1		0.2
Equity warrants	0.5		0.4
Other	0.2		0.2
	100.0	%	100.0	%

The following tables summarize the composition of Main Street’s total combined LMM, Private Loan and Middle Market portfolio investments by geographic region of the United States 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 June 30, 2025 and December 31, 2024 (this information excludes Other Portfolio investments and the External Investment Manager). The geographic composition is determined by the location of the corporate headquarters of the portfolio company.


Cost:	June 30, 2025		December 31, 2024
West	26.0	%	25.1	%
Midwest	21.2		22.7
Northeast	19.6		21.2
Southwest	19.5		16.7
Southeast	11.1		11.6
Canada	1.2		1.3
Other Non-United States	1.4		1.4
	100.0	%	100.0	%


Fair Value:	June 30, 2025		December 31, 2024
West	25.2	%	24.1	%
Southwest	23.1		20.1
Midwest	22.4		24.2
Northeast	17.0		19.4
Southeast	9.9		9.7
Canada	1.1		1.2
Other Non-United States	1.3		1.3
	100.0	%	100.0	%

The following tables summarize 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 June 30, 2025 and December 31, 2024 (this information excludes Other Portfolio investments and the External Investment Manager).


Cost:	June 30, 2025		December 31, 2024
Machinery	8.9	%	9.2	%
Internet Software & Services	6.7		7.1
Commercial Services & Supplies	6.5		5.5
Electrical Equipment	6.0		3.9
Distributors	5.7		4.0
Professional Services	5.3		5.4
Construction & Engineering	4.4		3.8
Diversified Consumer Services	4.0		4.3
IT Services	4.0		4.1
Auto Components	3.7		4.0
Containers & Packaging	3.7		3.8
Health Care Providers & Services	3.3		4.3
Textiles, Apparel & Luxury Goods	2.7		2.8
Tobacco	2.7		2.8
Energy Equipment & Services	2.6		2.8
Leisure Equipment & Products	2.3		2.4
Software	2.3		2.2
Computers & Peripherals	2.2		2.8
Communications Equipment	2.0		2.1
Specialty Retail	2.0		2.0
Media	1.6		1.7
Food Products	1.5		1.6
Chemicals	1.3		1.3
Food & Staples Retailing	1.3		1.6
Hotels, Restaurants & Leisure	1.3		1.3
Oil, Gas & Consumable Fuels	1.3		—
Aerospace & Defense	1.2		1.6
Internet & Catalog Retail	1.1		1.1
Health Care Equipment & Supplies	0.9		1.1
Diversified Financial Services	0.8		1.4
Building Products	0.4		1.5
Other (1)	6.3		6.5
	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:	June 30, 2025		December 31, 2024
Machinery	11.0	%	11.0	%
Commercial Services & Supplies	5.9		4.8
Distributors	5.8		4.2
Diversified Consumer Services	5.8		6.0
Electrical Equipment	5.6		3.7
Internet Software & Services	5.4		5.9
Professional Services	5.3		5.2
Construction & Engineering	4.7		4.3
Computers & Peripherals	4.0		4.6
Containers & Packaging	3.7		3.8
IT Services	3.4		3.7
Auto Components	3.3		3.6
Health Care Providers & Services	3.1		4.5
Tobacco	2.8		2.9
Energy Equipment & Services	2.7		2.9
Specialty Retail	2.5		2.5
Software	2.4		2.3
Textiles, Apparel & Luxury Goods	1.9		1.9
Communications Equipment	1.8		1.4
Leisure Equipment & Products	1.7		1.7
Media	1.7		1.9
Chemicals	1.2		1.2
Food Products	1.2		1.5
Oil, Gas & Consumable Fuels	1.2		—
Aerospace & Defense	1.1		1.6
Food & Staples Retailing	1.1		1.2
Internet & Catalog Retail	0.9		1.0
Diversified Financial Services	0.7		1.3
Building Products	0.4		1.4
Other (1)	7.7		8.0
	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.

- Definition

Tabular disclosure of the fair value measurement of assets using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes during the period attributable to the following: (1) total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings (or changes in net assets) and gains or losses recognized in other comprehensive income (loss), and a description of where those gains or losses included in earnings (or changes in net assets) are reported in the statement of income (or activities); (2) purchases, sales, issues, and settlements (each type disclosed separately); and (3) transfers in and transfers out of Level 3 (for example, transfers due to changes in the observability of significant inputs), by class of asset.

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