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CONSOLIDATED SCHEDULE OF INVESTMENTS IN AND ADVANCES TO AFFILIATES - Summary of Schedule of Investment (Details) - USD ($) $ in Thousands | Sep. 30, 2025 | Dec. 31, 2024 | Sep. 30, 2024 | Dec. 31, 2023
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Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Investment owned, percent of net assets | 196.64% | [1] | 0.03% | [2] |  |
Investment cost | $ 4,290,863 | [3] | $ 3,708,877 |  |  |
Investments, at fair value: | $ 4,306,154 |  | $ 3,659,978 |  |  |
Control investments |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Investment owned, percent of net assets | 5.13% |  | 5.69% |  |  |
Investment cost | $ 105,460 |  | $ 104,916 |  |  |
Investments, at fair value: | $ 112,323 |  | $ 113,179 |  | $ 113,097 | $ 115,004
Control investments | Majority Owned Control Investments |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Investment owned, percent of net assets | 4.75% |  | 5.10% |  |  |
Investment cost | $ 83,047 |  | $ 82,503 |  |  |
Investments, at fair value: | $ 104,047 |  | $ 101,522 |  | 101,054 | 103,487
Control investments | Other Control Investments |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Investment owned, percent of net assets | 0.37% |  | 0.59% |  |  |
Investment cost | $ 22,413 |  | $ 22,413 |  |  |
Investments, at fair value: | 8,276 |  | 11,657 |  | 12,043 | 11,517
Control investments | Coronado Aesthetics, LLC |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Investments, at fair value: | 344 |  |  |  | 319 |
Control investments | Coronado Aesthetics, LLC | Majority Owned Control Investments | Preferred Stock |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Investments, at fair value: | 343 |  | 69 |  | 318 | 260
Control investments | Coronado Aesthetics, LLC | Majority Owned Control Investments | Common Stock |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Investments, at fair value: | 1 |  | 0 |  | 1 | 2
Control investments | Coronado Aesthetics, LLC | Medical Devices & Equipment | Majority Owned Control Investments |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Investment cost | 250 |  | 250 |  |  |
Investments, at fair value: | $ 344 |  | $ 69 |  |  |
Control investments | Coronado Aesthetics, LLC | Medical Devices & Equipment | Majority Owned Control Investments | Common Stock |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Shares (in shares) | 180,000 |  | 180,000 |  |  |
Investment cost | $ 0 |  | $ 0 |  |  |
Investments, at fair value: | $ 1 |  | $ 0 |  |  |
Control investments | Coronado Aesthetics, LLC | Medical Devices & Equipment | Preferred Series A | Majority Owned Control Investments | Preferred Stock |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Shares (in shares) | 5,000,000 |  | 5,000,000 |  |  |
Investment cost | $ 250 |  | $ 250 |  |  |
Investments, at fair value: | 343 |  | 69 |  |  |
Control investments | Gibraltar Business Capital, LLC |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Investments, at fair value: | 60,193 |  |  |  | 57,302 |
Control investments | Gibraltar Business Capital, LLC | Majority Owned Control Investments | Unsecured Debt |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Investments, at fair value: | 38,006 |  | 36,212 |  | 35,633 | 34,478
Control investments | Gibraltar Business Capital, LLC | Majority Owned Control Investments | Member Units |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Investments, at fair value: | 22,187 |  | 23,051 |  | 21,669 | 28,034
Control investments | Gibraltar Business Capital, LLC | Diversified Financial Services | Majority Owned Control Investments |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Investment cost | 70,762 |  | 70,218 |  |  |
Investments, at fair value: | $ 60,193 |  | $ 59,263 |  |  |
Control investments | Gibraltar Business Capital, LLC | Diversified Financial Services | Majority Owned Control Investments | Unsecured Debt One |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Maturity Date | 2026-09 |  | 2026-09 |  |  |
Interest rate and floor, fixed | 3.45% |  | 3.45% |  |  |
Investment, interest rate, paid in kind | 8.05% |  | 8.05% |  |  |
Principal amount | $ 28,224 |  | $ 26,569 |  |  |
Investment cost | 28,081 |  | 26,337 |  |  |
Investments, at fair value: | $ 28,081 |  | $ 26,337 |  |  |
Control investments | Gibraltar Business Capital, LLC | Diversified Financial Services | Majority Owned Control Investments | Unsecured Debt Two |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Maturity Date | 2026-09 |  | 2026-09 |  |  |
Interest rate and floor, fixed | 11.95% |  | 11.95% |  |  |
Principal amount | $ 10,000 |  | $ 10,000 |  |  |
Investment cost | 9,925 |  | 9,875 |  |  |
Investments, at fair value: | $ 9,925 |  | $ 9,875 |  |  |
Control investments | Gibraltar Business Capital, LLC | Diversified Financial Services | Majority Owned Control Investments | Member Units |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Shares (in shares) | 1 |  | 1 |  |  |
Investment cost | $ 32,756 |  | $ 34,006 |  |  |
Investments, at fair value: | 22,187 |  | 23,051 |  |  |
Control investments | Hercules Adviser LLC |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Investments, at fair value: | 43,510 |  |  |  | 43,433 |
Control investments | Hercules Adviser LLC | Majority Owned Control Investments | Unsecured Debt |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Investments, at fair value: | 0 |  | 12,000 |  | 12,000 | 12,000
Control investments | Hercules Adviser LLC | Majority Owned Control Investments | Member Units |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Investments, at fair value: | 43,510 |  | 30,190 |  | 31,433 | 28,713
Control investments | Hercules Adviser LLC | Diversified Financial Services | Majority Owned Control Investments |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Investment cost | 12,035 |  | 12,035 |  |  |
Investments, at fair value: | $ 43,510 |  | $ 42,190 |  |  |
Control investments | Hercules Adviser LLC | Diversified Financial Services | Majority Owned Control Investments | Unsecured Debt |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Maturity Date |  |  | 2025-06 |  |  |
Interest rate and floor, fixed |  |  | 5.00% |  |  |
Principal amount |  |  | $ 12,000 |  |  |
Investment cost |  |  | 12,000 |  |  |
Investments, at fair value: |  |  | $ 12,000 |  |  |
Control investments | Hercules Adviser LLC | Diversified Financial Services | Majority Owned Control Investments | Member Units |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Shares (in shares) | 1 |  | 1 |  |  |
Investment cost | $ 12,035 |  | $ 35 |  |  |
Investments, at fair value: | 43,510 |  | 30,190 |  |  |
Control investments | Tectura Corporation |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Investments, at fair value: | 8,276 |  |  |  | 12,043 |
Control investments | Tectura Corporation | Other Control Investments | Preferred Stock |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Investments, at fair value: | 209 |  | 3,623 |  | 3,787 | 3,263
Control investments | Tectura Corporation | Other Control Investments | Common Stock |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Investments, at fair value: | 0 |  | 7 |  | 6 | 4
Control investments | Tectura Corporation | Other Control Investments | Senior Secured Debt |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Investments, at fair value: | 8,067 |  | 8,027 |  | $ 8,250 | $ 8,250
Control investments | Tectura Corporation | Consumer & Business Services | Other Control Investments |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Investment cost | 22,413 |  | 22,413 |  |  |
Investments, at fair value: | $ 8,276 |  | $ 11,657 |  |  |
Control investments | Tectura Corporation | Consumer & Business Services | Other Control Investments | Common Stock |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Shares (in shares) | 414,994,863 |  | 414,994,863 |  |  |
Investment cost | $ 900 |  | $ 900 |  |  |
Investments, at fair value: | $ 0 |  | $ 7 |  |  |
Control investments | Tectura Corporation | Consumer & Business Services | Other Control Investments | Senior Secured Debt |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Maturity Date | 2027-01 |  | 2027-01 |  |  |
Interest rate and floor, fixed | 8.25% |  | 8.25% |  |  |
Principal amount | $ 8,250 |  | $ 8,250 |  |  |
Investment cost | 8,250 |  | 8,250 |  |  |
Investments, at fair value: | $ 8,067 |  | $ 8,027 |  |  |
Control investments | Tectura Corporation | Consumer & Business Services | Preferred Series BB | Other Control Investments | Preferred Stock |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Shares (in shares) | 1,000,000 |  | 1,000,000 |  |  |
Investment cost | $ 0 |  | $ 0 |  |  |
Investments, at fair value: | $ 0 |  | $ 17 |  |  |
Control investments | Tectura Corporation | Consumer & Business Services | Series C Preferred Stock | Other Control Investments | Preferred Stock |  |  |  |  |  |
Investments in and Advances to Affiliates [Line Items] |  |  |  |  |  |
Shares (in shares) | 3,235,298 |  | 3,235,298 |  |  |
Investment cost | $ 13,263 |  | $ 13,263 |  |  |
Investments, at fair value: | $ 209 |  | $ 3,606 |  |  |
[1] | Value as a percent of net assets. All amounts are stated in U.S. Dollars unless otherwise noted. The Company uses the Standard Industrial Code for classifying the industry grouping of its portfolio companies.
[2] | Value as a percent of net assets. All amounts are stated in U.S. Dollars unless otherwise noted. The Company uses the Standard Industrial Code for classifying the industry grouping of its portfolio companies.
[3] | Gross unrealized appreciation, gross unrealized depreciation, and net unrealized appreciation for federal income tax purposes totaled $123.1 million, $108.1 million and $15.0 million, respectively. The tax cost of investments is $4.3 billion

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