Company: GAINI
Filing Date: 2025-11-06
Form Type: 424B2
Source: 0001193125-25-269767
Chunk: 118

Company: GLADSTONE INVESTMENT CORPORATION\DE
Filing Date: 2025-11-06
Form: 424B2
Chunk 118
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 reports filed by us with the SEC after the date of this prospectus and before the date that the offering of the securities by means of this prospectus is terminated will automatically update and, where applicable, supersede any information contained in this prospectus or incorporated by reference in this prospectus. We previously filed the following documents with the SEC, and such filings are incorporated by reference into this prospectus.

| • |     | The description of our common stock contained in our Amendment No. 1 to our Registration Statement on Form 8-A (File No. 814-00704), filed with the SEC on June 21, 2005, including any amendment or report filed for the purpose of updating such description. |

We also incorporate by reference into this prospectus additional documents that we may file with the SEC under Section 13(a), 13(c), 14 or 15(d) of the Exchange Act, from the filing of this prospectus until all of the securities offered by this prospectus have been sold or we otherwise terminate the offering of these securities, including all filings made after the date of the initial filing of the registration statement of which this prospectus is a part and prior to the effectiveness of the registration statement; provided, however, that information “furnished” under Item 2.02 or Item 7.01 of Form 8-Kor other information “furnished” to the SEC which is not deemed filed is not incorporated by reference in this prospectus and any accompanying prospectus supplement. Information that we subsequently file with the SEC will automatically update and may supersede information in this prospectus, any accompanying prospectus supplement and information previously filed with the SEC. These filings may also be accessed on the investors section of our website at www.gladstoneinvestment.com. Information contained on our website is not incorporated by reference into this prospectus. You may also request a copy of these filings (other than exhibits, unless the exhibits are specifically incorporated by reference into these documents) at no cost by writing, emailing or calling Investor Relations at the following address and telephone number: Investor Relations Gladstone Investment Corporation 1521 Westbranch Drive, Suite 100 McLean, Virginia 22102 (703) 287-5893 investment@gladstonecompanies.com 44

<div align='center'>**$60,000,000**</div>

#### 6.875% Notes due 2028

### PROSPECTUS SUPPLEMENT

#### Sole Book-Running Manager

#### B. Riley Securities