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N-2 - $ / shares | 9 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Dec. 31, 2023 | Sep. 30, 2023 | Mar. 31, 2023 | Dec. 31, 2022 | Sep. 30, 2022 | Mar. 31, 2022
Cover [Abstract] |  |  |  |  |  |
Entity Central Index Key | 0001321741 |  |  |  |  |
Amendment Flag | false |  |  |  |  |
Securities Act File Number | 814-00704 |  |  |  |  |
Document Type | 10-Q |  |  |  |  |
Entity Registrant Name | GLADSTONE INVESTMENT CORPORATION\DE |  |  |  |  |
Entity Address, Address Line One | 1521 WESTBRANCH DRIVE |  |  |  |  |
Entity Address, Address Line Two | SUITE 100 |  |  |  |  |
Entity Address, City or Town | MCLEAN |  |  |  |  |
Entity Address, State or Province | VA |  |  |  |  |
Entity Address, Postal Zip Code | 22102 |  |  |  |  |
City Area Code | 703 |  |  |  |  |
Local Phone Number | 287-5800 |  |  |  |  |
Entity Emerging Growth Company | false |  |  |  |  |
Financial Highlights [Abstract] |  |  |  |  |  |
Senior Securities, Note [Text Block] | As of December 31, 2023, our asset coverage ratio on our senior securities representing indebtedness was 206.9%. |  |  |  |  |
General Description of Registrant [Abstract] |  |  |  |  |  |
Investment Objectives and Practices [Text Block] | We were established for the purpose of investing in debt and equity securities of established private businesses operating in the United States (“U.S.”). Our investment objectives are to: (i) achieve and grow current income by investing in debt securities of established businesses that we believe will provide stable earnings and cash flow to pay expenses, make principal and interest payments on our outstanding indebtedness, and make distributions to our stockholders that grow over time; and (ii) provide our stockholders with long-term capital appreciation in the value of our assets by investing in equity securities of established businesses, generally in combination with the aforementioned debt securities, that we believe can grow over time to permit us to sell our equity investments for capital gains. To achieve our objectives, our investment strategy is to invest in several categories of debt and equity securities, with individual investments generally totaling up to $75 million, although investment size may vary depending upon our total assets or available capital at the time of investment. We expect that our investment portfolio over time will consist of approximately 75% in debt investments and 25% in equity investments, at cost. We focus on investing in lower middle market private businesses (which we generally define as companies with annual earnings before interest, taxes, depreciation and amortization (“EBITDA”) of $4 million to $15 million) (“Lower Middle Market”) in the U.S. that meet certain criteria, including: the sustainability of the business’ free cash flow and its ability to grow it over time, adequate assets for loan collateral, experienced management teams with a significant ownership interest in the portfolio company, reasonable capitalization of the portfolio company, including an ample equity contribution or cushion based on prevailing enterprise valuation multiples, and the potential to realize appreciation and gain liquidity in our equity position, if any. We anticipate that liquidity in our equity position will be achieved through a merger or acquisition of the portfolio company, a public offering of the portfolio company’s stock, or, to a lesser extent, by exercising our right to require the portfolio company to repurchase our warrants, though there can be no assurance that we will always have these rights. We invest in portfolio companies that seek funds for management buyouts and/or growth capital to finance acquisitions, recapitalize or, to a lesser extent, refinance their existing debt facilities. We seek to avoid investing in high-risk, early-stage enterprises. |  |  |  |  |
Risk [Text Block] | RISK FACTORS. Our business is subject to certain risks and events that, if they occur, could adversely affect our financial condition and results of operations and the trading price of our securities. For a discussion of these risks, please refer to the section captioned “Item 1A. Risk Factors” in Part I of our Annual Report on Form 10-K for the fiscal year ended March 31, 2023, as filed with the SEC on May 10, 2023. The risks described in our Annual Report are not the only risks we face. Additional risks and uncertainties not currently known to us or that we currently deem to be immaterial also may materially and adversely affect our business, financial condition and/or operating results. |  |  |  |  |
Share Price | $ 14.15 |  |  |  |  |
NAV Per Share | $ 13.01 | $ 14.03 | $ 13.09 | $ 13.43 | $ 13.31 | $ 13.43
Latest Premium (Discount) to NAV [Percent] | 8.80% |  |  |  |  |
Capital Stock, Long-Term Debt, and Other Securities [Abstract] |  |  |  |  |  |
Long Term Debt [Table Text Block] | Notes Payable |  |  |  |  |
Revolving Line Of Credit [Member] |  |  |  |  |  |
Capital Stock, Long-Term Debt, and Other Securities [Abstract] |  |  |  |  |  |
Long Term Debt [Table Text Block] | Revolving Line of Credit On October 30, 2023, we, through our wholly-owned subsidiary, Business Investment, entered into Amendment No. 8 to the Credit Facility with KeyBank as administrative agent, lead arranger, managing agent and lender, the Adviser, as servicer, and certain other lenders party thereto. Among other things, the revolving period was extended to October 30, 2026, and if not renewed or extended by such date, all principal and interest will be due and payable by October 30, 2028 (two years after the revolving period end date). Advances under the Credit Facility generally bear interest at 30-day Term SOFR, subject to a floor of 0.35%, plus 3.15% per annum until October 30, 2026, with the margin then increasing to 3.40% for the period from October 30, 2026 to October 30, 2027, and increasing further to 3.65% thereafter with a SOFR credit spread adjustment of 10 basis points. The Credit Facility has an unused commitment fee on the daily unused commitment amount of 0.50% per annum if the daily unused commitment amount is less than or equal to 50% of the total commitment amount, 0.75% per annum if the daily unused commitment amount is greater than 50% but less than or equal to 65% of the total commitment amount, and 1.00% per annum if the daily unused commitment amount is greater than 65% of the total commitment amount. The size of the Credit Facility was reduced from $180.0 million to $135.0 million. Previously, on April 10, 2023, we, through our wholly-owned subsidiary, Business Investment, entered into Amendment No. 7 to the Credit Facility with KeyBank as administrative agent, lead arranger, managing agent and lender, the Adviser, as servicer, and certain other lenders party thereto. The reference rate was updated from LIBOR to Term SOFR plus an 11 basis point credit spread adjustment. Previously, on March 8, 2021, we, through our wholly-owned subsidiary, Business Investment, entered into Amendment No. 6 to the Credit Facility with KeyBank as administrative agent, lead arranger, managing agent and lender, the Adviser, as servicer, and certain other lenders party thereto. The revolving period was extended to February 29, 2024, and if not renewed or extended by such date, all principal and interest will be due and payable on February 28, 2026 (two years after the revolving period end date). |  |  |  |  |
Long Term Debt, Structuring [Text Block] | Revolving Line of Credit On October 30, 2023, we, through our wholly-owned subsidiary, Business Investment, entered into Amendment No. 8 to the Credit Facility with KeyBank as administrative agent, lead arranger, managing agent and lender, the Adviser, as servicer, and certain other lenders party thereto. Among other things, the revolving period was extended to October 30, 2026, and if not renewed or extended by such date, all principal and interest will be due and payable by October 30, 2028 (two years after the revolving period end date). Advances under the Credit Facility generally bear interest at 30-day Term SOFR, subject to a floor of 0.35%, plus 3.15% per annum until October 30, 2026, with the margin then increasing to 3.40% for the period from October 30, 2026 to October 30, 2027, and increasing further to 3.65% thereafter with a SOFR credit spread adjustment of 10 basis points. The Credit Facility has an unused commitment fee on the daily unused commitment amount of 0.50% per annum if the daily unused commitment amount is less than or equal to 50% of the total commitment amount, 0.75% per annum if the daily unused commitment amount is greater than 50% but less than or equal to 65% of the total commitment amount, and 1.00% per annum if the daily unused commitment amount is greater than 65% of the total commitment amount. The size of the Credit Facility was reduced from $180.0 million to $135.0 million. Previously, on April 10, 2023, we, through our wholly-owned subsidiary, Business Investment, entered into Amendment No. 7 to the Credit Facility with KeyBank as administrative agent, lead arranger, managing agent and lender, the Adviser, as servicer, and certain other lenders party thereto. The reference rate was updated from LIBOR to Term SOFR plus an 11 basis point credit spread adjustment. Previously, on March 8, 2021, we, through our wholly-owned subsidiary, Business Investment, entered into Amendment No. 6 to the Credit Facility with KeyBank as administrative agent, lead arranger, managing agent and lender, the Adviser, as servicer, and certain other lenders party thereto. The revolving period was extended to February 29, 2024, and if not renewed or extended by such date, all principal and interest will be due and payable on February 28, 2026 (two years after the revolving period end date). |  |  |  |  |
5.00% Notes Due 2026 [Member] |  |  |  |  |  |
Capital Stock, Long-Term Debt, and Other Securities [Abstract] |  |  |  |  |  |
Long Term Debt [Table Text Block] | 5.00% Notes due 2026 In March 2021, we completed a public offering of the 5.00% 2026 Notes with an aggregate principal amount of $127.9 million, which resulted in net proceeds of approximately $123.8 million after deducting underwriting discounts, commissions and offering costs borne by us. The 5.00% 2026 Notes are traded under the ticker symbol “GAINN” on Nasdaq. The 5.00% 2026 Notes will mature on May 1, 2026 and may be redeemed in whole or in part at any time or from time to time at the Company’s option. The 5.00% 2026 Notes bear interest at a rate of 5.00% per year (which equates to $6.4 million per year), payable quarterly in arrears. The indenture relating to the 5.00% 2026 Notes contains certain covenants, including (i) an inability to incur additional debt or issue additional debt or preferred securities unless the Company’s asset coverage meets the threshold specified in the 1940 Act after such borrowing, (ii) an inability to declare any dividend or distribution (except a dividend payable in our stock) on a class of our capital stock or to purchase shares of our capital stock unless the Company’s asset coverage meets the threshold specified in the 1940 Act at the time of (and giving effect to) such declaration or purchase, and (iii) if, at any time, we are not subject to the reporting requirements of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), we will provide the holders of the 5.00% 2026 Notes and the trustee with audited annual consolidated financial statements and unaudited interim consolidated financial statements. The 5.00% 2026 Notes are recorded at the aggregate principal amount, less underwriting discounts, commissions, and offering costs, on our accompanying Consolidated Statements of Assets and Liabilities. Total underwriting discounts, commissions, and offering costs related to this offering were $4.1 million, which have been recorded as discounts to the aggregate principal amount on our accompanying Consolidated Statements of Assets and Liabilities and are being amortized over the period ending May 1, 2026, the maturity date. |  |  |  |  |
Long Term Debt, Title [Text Block] | 5.00% Notes due 2026 |  |  |  |  |
Long Term Debt, Structuring [Text Block] | In March 2021, we completed a public offering of the 5.00% 2026 Notes with an aggregate principal amount of $127.9 million, which resulted in net proceeds of approximately $123.8 million after deducting underwriting discounts, commissions and offering costs borne by us. The 5.00% 2026 Notes are traded under the ticker symbol “GAINN” on Nasdaq. The 5.00% 2026 Notes will mature on May 1, 2026 and may be redeemed in whole or in part at any time or from time to time at the Company’s option. The 5.00% 2026 Notes bear interest at a rate of 5.00% per year (which equates to $6.4 million per year), payable quarterly in arrears. |  |  |  |  |
Long Term Debt, Dividends and Covenants [Text Block] | The indenture relating to the 5.00% 2026 Notes contains certain covenants, including (i) an inability to incur additional debt or issue additional debt or preferred securities unless the Company’s asset coverage meets the threshold specified in the 1940 Act after such borrowing, (ii) an inability to declare any dividend or distribution (except a dividend payable in our stock) on a class of our capital stock or to purchase shares of our capital stock unless the Company’s asset coverage meets the threshold specified in the 1940 Act at the time of (and giving effect to) such declaration or purchase, and (iii) if, at any time, we are not subject to the reporting requirements of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), we will provide the holders of the 5.00% 2026 Notes and the trustee with audited annual consolidated financial statements and unaudited interim consolidated financial statements. |  |  |  |  |
4.875% Notes Due 2028 [Member] |  |  |  |  |  |
Capital Stock, Long-Term Debt, and Other Securities [Abstract] |  |  |  |  |  |
Long Term Debt [Table Text Block] | 4.875% Notes due 2028 In August 2021, we completed a public offering of the 4.875% 2028 Notes with an aggregate principal amount of $134.6 million, which resulted in net proceeds of approximately $131.3 million after deducting underwriting discounts, commissions and offering costs borne by us. The 4.875% 2028 Notes are traded under the ticker symbol “GAINZ” on Nasdaq. The 4.875% 2028 Notes will mature on November 1, 2028 and may be redeemed in whole or in part at any time or from time to time at the Company’s option. The 4.875% 2028 Notes bear interest at a rate of 4.875% per year (which equates to $6.6 million per year), payable quarterly in arrears. The indenture relating to the 4.875% 2028 Notes contains certain covenants, including (i) an inability to incur additional debt or issue additional debt or preferred securities unless the Company’s asset coverage meets the threshold specified in the 1940 Act after such borrowing, (ii) an inability to declare any dividend or distribution (except a dividend payable in our stock) on a class of our capital stock or to purchase shares of our capital stock unless the Company’s asset coverage meets the threshold specified in the 1940 Act at the time of (and giving effect to) such declaration or purchase, and (iii) if, at any time, we are not subject to the reporting requirements of the Exchange Act, we will provide the holders of the 4.875% 2028 Notes and the trustee with audited annual consolidated financial statements and unaudited interim consolidated financial statements. The 4.875% 2028 Notes are recorded at the aggregate principal amount, less underwriting discounts, commissions, and offering costs, on our accompanying Consolidated Statements of Assets and Liabilities. Total underwriting discounts, commissions, and offering costs related to this offering were $3.3 million, which have been recorded as discounts to the aggregate principal amount on our accompanying Consolidated Statements of Assets and Liabilities and are being amortized over the period ending November 1, 2028, the maturity date. |  |  |  |  |
Long Term Debt, Title [Text Block] | 4.875% Notes due 2028 |  |  |  |  |
Long Term Debt, Structuring [Text Block] | In August 2021, we completed a public offering of the 4.875% 2028 Notes with an aggregate principal amount of $134.6 million, which resulted in net proceeds of approximately $131.3 million after deducting underwriting discounts, commissions and offering costs borne by us. The 4.875% 2028 Notes are traded under the ticker symbol “GAINZ” on Nasdaq. The 4.875% 2028 Notes will mature on November 1, 2028 and may be redeemed in whole or in part at any time or from time to time at the Company’s option. The 4.875% 2028 Notes bear interest at a rate of 4.875% per year (which equates to $6.6 million per year), payable quarterly in arrears. |  |  |  |  |
Long Term Debt, Dividends and Covenants [Text Block] | The indenture relating to the 4.875% 2028 Notes contains certain covenants, including (i) an inability to incur additional debt or issue additional debt or preferred securities unless the Company’s asset coverage meets the threshold specified in the 1940 Act after such borrowing, (ii) an inability to declare any dividend or distribution (except a dividend payable in our stock) on a class of our capital stock or to purchase shares of our capital stock unless the Company’s asset coverage meets the threshold specified in the 1940 Act at the time of (and giving effect to) such declaration or purchase, and (iii) if, at any time, we are not subject to the reporting requirements of the Exchange Act, we will provide the holders of the 4.875% 2028 Notes and the trustee with audited annual consolidated financial statements and unaudited interim consolidated financial statements. |  |  |  |  |
8.00% Notes Due 2028 [Member] |  |  |  |  |  |
Capital Stock, Long-Term Debt, and Other Securities [Abstract] |  |  |  |  |  |
Long Term Debt [Table Text Block] | 8.00% Notes due 2028 In May 2023, we completed a public offering of the 8.00% 2028 Notes with an aggregate principal amount of $74.8 million, which resulted in net proceeds of approximately $72.3 million after deducting underwriting discounts, commissions and offering costs borne by us. The 8.00% 2028 Notes are traded under the ticker symbol “GAINL” on Nasdaq. The 8.00% 2028 Notes will mature on August 1, 2028 and may be redeemed in whole or in part at any time or from time to time at the Company’s option on or after August 1, 2025. The 8.00% 2028 Notes bear interest at a rate of 8.00% per year (which equates to $6.0 million per year), payable quarterly in arrears. The indenture relating to the 8.00% 2028 Notes contains certain covenants, including (i) an inability to incur additional debt or issue additional debt or preferred securities unless the Company’s asset coverage meets the threshold specified in the 1940 Act after such borrowing, (ii) an inability to declare any dividend or distribution (except a dividend payable in our stock) on a class of our capital stock or to purchase shares of our capital stock unless the Company’s asset coverage meets the threshold specified in the 1940 Act at the time of (and giving effect to) such declaration or purchase, and (iii) if, at any time, we are not subject to the reporting requirements of the Exchange Act, we will provide the holders of the 8.00% 2028 Notes and the trustee with audited annual consolidated financial statements and unaudited interim consolidated financial statements. The 8.00% 2028 Notes are recorded at the aggregate principal amount, less underwriting discounts, commissions, and offering costs, on our accompanying Consolidated Statements of Assets and Liabilities. Total underwriting discounts, commissions, and offering costs related to this offering were $2.5 million, which have been recorded as discounts to the aggregate principal amount on our accompanying Consolidated Statements of Assets and Liabilities and are being amortized over the period ending August 1, 2028, the maturity date. |  |  |  |  |
Long Term Debt, Title [Text Block] | 8.00% Notes due 2028 |  |  |  |  |
Long Term Debt, Structuring [Text Block] | In May 2023, we completed a public offering of the 8.00% 2028 Notes with an aggregate principal amount of $74.8 million, which resulted in net proceeds of approximately $72.3 million after deducting underwriting discounts, commissions and offering costs borne by us. The 8.00% 2028 Notes are traded under the ticker symbol “GAINL” on Nasdaq. The 8.00% 2028 Notes will mature on August 1, 2028 and may be redeemed in whole or in part at any time or from time to time at the Company’s option on or after August 1, 2025. The 8.00% 2028 Notes bear interest at a rate of 8.00% per year (which equates to $6.0 million per year), payable quarterly in arrears. |  |  |  |  |
Long Term Debt, Dividends and Covenants [Text Block] | The indenture relating to the 8.00% 2028 Notes contains certain covenants, including (i) an inability to incur additional debt or issue additional debt or preferred securities unless the Company’s asset coverage meets the threshold specified in the 1940 Act after such borrowing, (ii) an inability to declare any dividend or distribution (except a dividend payable in our stock) on a class of our capital stock or to purchase shares of our capital stock unless the Company’s asset coverage meets the threshold specified in the 1940 Act at the time of (and giving effect to) such declaration or purchase, and (iii) if, at any time, we are not subject to the reporting requirements of the Exchange Act, we will provide the holders of the 8.00% 2028 Notes and the trustee with audited annual consolidated financial statements and unaudited interim consolidated financial statements. |  |  |  |  |

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