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INVESTMENTS - Schedule of Contractual Principal Repayment and Maturity (Details) - USD ($) $ in Thousands | Jun. 30, 2025 | Sep. 30, 2024 | [1]
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Investments, Debt and Equity Securities [Abstract] |  |
2025 | $ 4,951 |
2026 | 71,503 |
2027 | 160,622 |
2028 | 204,797 |
2029 | 105,614 |
Thereafter | 153,214 |
Total contractual repayments | 700,701 |
Adjustments to cost basis of debt investments | (580) |
Investments in equity securities | 77,730 |
Investment owned, at cost | 777,851 | $ 771,011
Debt investments with maturity dates prior to period end | $ 500 |
[1] | Cumulative gross unrealized depreciation for federal income tax purposes is $66.1 million; cumulative gross unrealized appreciation for federal income tax purposes is $85.8 million. Cumulative net unrealized appreciation is $19.7 million, based on a tax cost of $776.5 million.

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