FAIR VALUE HIERARCHY FOR INVESTMENTS—PORTFOLIO COMPOSITION (Tables)

3 Months Ended

Mar. 31, 2026

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 March 31, 2026 and December 31, 2025 is as follows:


Type of Investment	Fair Value as of March 31, 2026 (in thousands)		Valuation Technique	Significant Unobservable Inputs	Range (4)	Weighted-Average (4)(5)	Median (4)
Equity investments	$	1,886,842	Discounted cash flow	WACC	9.3% - 23.3%	14.6%	15.1%
			Market comparable / Enterprise value	EBITDA multiple (1) (3)	4.3x - 9.0x (2)	7.4x	6.6x
Debt investments	$	3,753,011	Discounted cash flow	Risk adjusted discount rate (6)	7.6% - 18.7% (2)	11.8%	11.4%
				Expected principal recovery percentage	0.0% - 500.0%	99.3%	100.0%
Debt investments	$	10,231	Market approach	Third-party quote	14.5 - 61.4	51.2	41.2
Total Level 3 investments	$	5,650,084

___________________________

(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 - 16.0x and the range for risk adjusted discount rate is 5.4% - 34.6%.

(3)The fair value determination of the equity investment in the External Investment Manager is based on a fee multiple of 7.7x, which represents a discounted, blended multiple based on (i) the multiples for similar businesses in active markets and (ii) 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, 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 determination of the equity investment in the External Investment Manager is based on a fee multiple of 7.8x, which represents a discounted, blended multiple based on (i) the multiples for similar businesses in active markets and (ii) 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 three months ended March 31, 2026 and 2025 is as follows (in thousands):


Type of Investment	Fair Value as of December 31, 2025		Transfers Into (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 March 31, 2026
Debt	$	3,607,331	$	—	$	(164,734)	$	360,021	$	(1,820)	$	(37,485)	$	(71)	$	3,763,242
Equity	1,858,205		—		(25,196)		33,933		(17,607)		6,677		71		1,856,083
Equity Warrant	31,169		—		—		—		—		(410)		—		30,759
	$	5,496,705	$	—	$	(189,930)	$	393,954	$	(19,427)	$	(31,218)	$	—	$	5,650,084

___________________________

(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, 2024		Transfers Into (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 March 31, 2025
Debt	$	3,278,365	$	—	$	(179,192)	$	222,305	$	30,440	$	(8,711)	$	(27,250)	$	3,315,957
Equity	1,637,181		(16,810)		(12,868)		23,679		(1,532)		37,887		27,250		1,694,787
Equity Warrant	17,123		—		—		—		—		4,760		—		21,883
	$	4,932,669	$	(16,810)	$	(192,060)	$	245,984	$	28,908	$	33,936	$	—	$	5,032,627

___________________________

(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 March 31, 2026 and December 31, 2025, 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)
March 31, 2026	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	$	3,227,396	$	—	$	—	$	3,227,396
Private Loan portfolio investments	1,993,902		—		—		1,993,902
Middle Market portfolio investments	81,886		—		—		81,886
Other Portfolio investments	138,507		24,667		—		113,840
External Investment Manager	233,060		—		—		233,060

Total investments	$	5,674,751	$	24,667	$	—	$	5,650,084


			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

Schedule of Investment Holdings

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


	March 31, 2026
	LMM (a)			Private Loan

	(dollars in millions)
Number of portfolio companies	93			85
Fair value	$	3,227.4		$	1,993.9
Cost	$	2,577.0		$	2,057.0
Debt investments as a % of portfolio (at cost)	72.0		%	94.5		%
Equity investments as a % of portfolio (at cost)	28.0		%	5.5		%
% of debt investments at cost secured by first priority lien	99.4		%	99.3		%
Weighted-average annual effective yield (b)	12.6		%	10.3		%
Average EBITDA (c)	$	11.2		$	34.2

___________________________

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

(b)The weighted-average annual effective yields were computed using the effective interest rates for all debt investments as of March 31, 2026, including amortization of deferred debt origination fees and accretion of original issue discount but excluding fees payable upon repayment of the debt investments and any debt investments on non-accrual status, and are weighted based upon the principal amount of each applicable debt investment as of March 31, 2026. The weighted-average annual effective yield on Main Street’s debt portfolio as of March 31, 2026, including debt investments on non-accrual status, was 12.1% for its LMM portfolio investments and 9.7% 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 their 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, 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 their 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.

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 March 31, 2026 and December 31, 2025, is as follows (this information excludes Other Portfolio investments and the External Investment Manager, which are discussed above):


Cost:	March 31, 2026		December 31, 2025
First lien debt	81.2	%	80.9	%
Equity	18.0		18.6
Second lien debt	0.4		0.1
Equity warrants	0.2		0.2
Other	0.2		0.2
	100.0	%	100.0	%


Fair Value:	March 31, 2026		December 31, 2025
First lien debt	70.2	%	69.8	%
Equity	28.7		29.4
Second lien debt	0.3		—
Equity warrants	0.6		0.6
Other	0.2		0.2
	100.0	%	100.0	%

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 March 31, 2026 and December 31, 2025, is as follows (this information excludes Other Portfolio investments and the External Investment Manager):


Cost:	March 31, 2026		December 31, 2025
West	25.3	%	25.3	%
Southwest	19.5		19.0
Midwest	18.8		19.2
Southeast	18.6		17.5
Northeast	14.5		15.4
Canada	2.1		2.2
Other Non-U.S.	1.2		1.4
	100.0	%	100.0	%


Fair Value:	March 31, 2026		December 31, 2025
West	24.5	%	24.8	%
Southwest	23.3		23.0
Midwest	19.8		20.1
Southeast	16.9		15.8
Northeast	12.5		13.1
Canada	1.9		1.9
Other Non-U.S.	1.1		1.3
	100.0	%	100.0	%

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 March 31, 2026 and December 31, 2025, is as follows (this information excludes Other Portfolio investments and the External Investment Manager):


Cost:	March 31, 2026		December 31, 2025
Machinery	8.3	%	8.3	%
Construction & Engineering	7.6		6.1
Electrical Equipment	6.4		5.9
Commercial Services & Supplies	5.4		6.8
Professional Services	5.1		5.3
Distributors	4.8		5.0
Diversified Consumer Services	4.5		4.7
Health Care Providers & Services	4.1		4.2
Internet Software & Services	3.8		4.2
Aerospace & Defense	3.8		2.3
IT Services	3.6		3.7
Containers & Packaging	3.2		3.3
Auto Components	3.1		3.2
Tobacco	2.4		2.5
Textiles, Apparel & Luxury Goods	2.3		2.5
Leisure Equipment & Products	2.1		2.1
Computers & Peripherals	2.0		2.0
Software	2.0		2.1
Media	2.0		1.6
Energy Equipment & Services	1.9		2.4
Specialty Retail	1.9		2.0
Communications Equipment	1.8		1.9
Air Freight & Logistics	1.6		1.5
Trading Companies & Distributors	1.6		1.8
Food Products	1.4		1.4
Chemicals	1.4		1.4
Food & Staples Retailing	1.3		1.4
Beverages	1.3		1.2
Oil, Gas & Consumable Fuels	1.0		1.1
Hotels, Restaurants & Leisure	1.0		1.1
Internet & Catalog Retail	0.9		1.0
Other (1)	6.4		6.0
	100.0	%	100.0	%

___________________________

(1)Includes various industries with each industry individually representing less than 1.0% of the total combined LMM, Private Loan and Middle Market portfolio investments at each date.


Fair Value:	March 31, 2026		December 31, 2025
Machinery	10.2	%	10.2	%
Construction & Engineering	7.6		6.5
Electrical Equipment	6.8		5.9
Diversified Consumer Services	5.8		6.1
Distributors	5.4		5.5
Professional Services	5.1		5.2
Commercial Services & Supplies	4.5		5.9
IT Services	3.8		3.8
Computers & Peripherals	3.7		3.6
Health Care Providers & Services	3.7		3.8
Aerospace & Defense	3.4		2.0
Containers & Packaging	3.3		3.4
Internet Software & Services	3.1		3.4
Auto Components	3.0		3.0
Tobacco	2.5		2.6
Specialty Retail	2.3		2.4
Software	2.2		2.2
Media	2.0		1.6
Energy Equipment & Services	1.9		2.5
Textiles, Apparel & Luxury Goods	1.8		1.9
Communications Equipment	1.6		1.7
Air Freight & Logistics	1.5		1.3
Leisure Equipment & Products	1.4		1.4
Trading Companies & Distributors	1.4		1.6
Chemicals	1.2		1.3
Beverages	1.1		1.1
Food & Staples Retailing	1.0		1.1
Food Products	1.0		1.1
Oil, Gas & Consumable Fuels	0.9		1.0
Other (1)	6.8		6.9
	100.0	%	100.0	%

___________________________

(1)Includes various industries with each industry individually representing 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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