Free Writing Prospectus (Form FWP)

Filed Pursuant to Rule 433

Issuer Free Writing Prospectus dated November 6, 2025

Relating to Prospectus dated April 18, 2024

Registration No. 333-277452

Pricing Terms

GLADSTONE INVESTMENT CORPORATION

$60,000,000

6.875% Notes Due 2028

Pricing Term Sheet

November 6, 2025

The following sets forth the final terms of the 6.875% Notes due 2028 (the "Notes") and should only be read together with the prospectus dated April 18, 2024, relating to these securities. All references to dollar amounts are references to U.S. dollars. 

Investors are advised to carefully consider the investment objective, risks, charges and expenses of the Company before investing.

This pricing term sheet is not an offer to sell or the solicitation of offers to buy, nor will there be any sale of the Notes referred to in this pricing term sheet, in any jurisdiction where such offer, solicitation or sale would be unlawful prior to the registration or qualification under the securities laws of such jurisdiction.

A shelf registration statement relating to these securities is on file with, and has been declared effective by, the SEC. Before you invest, you should read the prospectus in that registration statement and other documents the issuer has filed with the SEC for more complete information about the issuer and this offering. You may obtain these documents for free by visiting EDGAR on the SEC Web site at www.sec.gov. Alternatively, the issuer, the underwriter or any dealer participating in the offering will arrange to send you the prospectus if you request it by contacting: B. Riley Securities, Inc., Attention: Syndicate Prospectus Department, 1300 17th Street North, Suite 1300, Arlington, Virginia 22209, by telephone at (703) 312-9580, or by email at [email protected].

Exhibit A

Description of the Notes

The Notes will be issued under a base indenture dated as of May 22, 2020 and a sixth supplemental indenture thereto to be dated November 10, 2025, between us and UMB Bank, National Association, as trustee. We refer to the indenture and the sixth supplemental indenture collectively as the "indenture" and to UMB Bank, National Association as the "trustee." This section includes a summary description of the material terms of the Notes and the indenture. Because this section is a summary, however, it does not describe every aspect of the Notes and the indenture. For certain risks relating to an investment in the Notes, please see "Risk Factors" in our most recent annual report on Form 10-K.

General

The indenture does not limit the amount of debt (including secured debt) that may be issued by us or our subsidiaries under the indenture or otherwise, but does contain a covenant regarding our asset coverage that would have to be satisfied at the time of our incurrence of additional indebtedness. See "Covenants" and "Events of Default." Other than as described under "Covenants" below, the indenture does not restrict us from paying dividends or issuing or repurchasing our other securities. Other than restrictions described under "Merger or Consolidation" below, the indenture does not contain any covenants or other provisions designed to afford holders of the Notes protection in the event of a highly leveraged transaction involving us or if our credit rating declines as the result of a takeover, recapitalization, highly leveraged transaction or similar restructuring involving us that could adversely affect your investment in the Notes.

We may, without the consent of the holders of the Notes, issue additional notes under the indenture with the same terms (except for the issue date, public offering price, and if applicable, the initial interest payment date) and with the same CUSIP numbers as the Notes offered hereby in an unlimited aggregate principal amount; provided that such additional notes must be treated as part of the same issue as the Notes offered hereby for federal income tax purposes.

Global Securities

Each Note will be issued in book-entry form and represented by a global security that we deposit with and register in the name of DTC or its nominee. A global security may not be transferred to or registered in the name of anyone other than the depositary or its nominee, unless special termination situations arise. As a result of these arrangements, the depositary, or its nominee, will be the sole registered owner and holder of all the Notes represented by a global security, and investors will be permitted to own only beneficial interests in a global security.

Termination of a Global Security

If a global security is terminated for any reason, interests in it will be exchanged for certificates in non-book-entry form (certificated securities). After that exchange, the choice of whether to hold the certificated Notes directly or in street name will be up to the investor. Investors must consult their own banks or brokers to find out how to have their interests in a global security transferred on termination to their own names, so that they will be holders.

Conversion and Exchange

The Notes are not convertible into or exchangeable for other securities.

Payment and Paying Agents

We will pay interest to the person listed in the trustee's records as the owner of the Notes at the close of business on a particular day in advance of each due date for interest, even if that person no longer owns the Note on the interest due date (the "record date"). Because we will pay all the interest for an interest period to the holders on the record date, holders buying and selling the Notes must work out between themselves the appropriate purchase price. The most common manner is to adjust the sales price of the Notes to prorate interest fairly between buyer and seller based on their respective ownership periods within the particular interest period. This prorated interest amount is called "accrued interest."

Payments on Global Securities

We will make payments on the Notes so long as they are represented by a global security in accordance with the applicable policies of the depositary as in effect from time to time. Under those policies, we will make payments directly to the depositary, or its nominee, and not to any indirect holders who own beneficial interests in the global security.

Payments on Certificated Securities

In the event the Notes become represented by certificated securities, we will make payments on the Notes as follows. We will pay interest that is due on an interest payment date to the holder of the Notes as shown on the trustee's records as of the close of business on the regular record date. We will make all payments of principal and premium, if any, by check at the office of the applicable trustee in Kansas City, Missouri and/or at other offices that may be specified in the indenture or a notice to holders against surrender of the Note.

Alternatively, if the holder asks us to do so, we will pay any amount that becomes due on the debt security by wire transfer of immediately available funds to an account at a bank in Kansas City, Missouri, on the due date. To request payment by wire, the holder must give the applicable trustee or other paying agent appropriate transfer instructions at least 15 business days before the requested wire payment is due. In the case of any interest payment due on an interest payment date, the instructions must be given by the person who is the holder on the relevant regular record date. Any wire instructions, once properly given, will remain in effect unless and until new instructions are given in the manner described above.

Payment When Offices Are Closed

If any payment is due on the Notes on a day that is not a business day, we will make the payment on the next day that is a business day. Payments made on the next business day in this situation will be treated under the indenture as if they were made on the original due date. Such payment will not result in a default under the Notes or the indenture, and no interest will accrue on the payment amount from the original due date to the next day that is a business day.

Events of Default

You will have rights if an Event of Default occurs in respect of the Notes and the Event of Default is not cured, as described later in this subsection.

The term "Event of Default" in respect of the Notes means any of the following:

An Event of Default for the Notes may, but does not necessarily, constitute an Event of Default for any other series of debt securities issued under the same or any other indenture. The trustee may withhold notice to the holders of the Notes of any default, except in the payment of principal or interest, if it in good faith considers the withholding of notice to be in the best interests of the holders.

Remedies if an Event of Default Occurs

If an Event of Default has occurred and is continuing, the trustee or the holders of not less than 25% in principal amount of the Notes may declare the entire principal amount of all the Notes to be due and immediately payable, but this does not entitle any holder of Notes to any redemption payout or redemption premium. This is called a declaration of acceleration of maturity. In certain circumstances, a declaration of acceleration of maturity may be canceled by the holders of a majority in principal amount of the Notes if (1) we have deposited with the trustee all amounts due and owing with respect to the Notes (other than principal or any payment that has become due solely by reason of such acceleration) and certain other amounts, and (2) any other Events of Default have been cured or waived.

Except in cases of default, where the trustee has some special duties, the trustee is not required to take any action under the indenture at the request of any holders unless the holders offer the trustee indemnity, security or both against costs, expenses and liability reasonably satisfactory to it (called an "indemnity"). If indemnity reasonably satisfactory to the trustee is provided, the holders of a majority in principal amount of the Notes may direct the time, method and place of conducting any lawsuit or other formal legal action seeking any remedy available to the trustee. The trustee may refuse to follow those directions in certain circumstances. No delay or omission in exercising any right or remedy will be treated as a waiver of that right, remedy or Event of Default.

Before you are allowed to bypass the trustee and bring your own lawsuit or other formal legal action or take other steps to enforce your rights or protect your interests relating to the Notes, the following must occur:

However, you are entitled at any time to bring a lawsuit for the payment of money due on your Notes on or after the due date.

Book-entry and other indirect holders should consult their banks or brokers for information on how to give notice or direction to or make a request of the trustee and how to declare or cancel an acceleration of maturity.

Each year, we will furnish to the trustee a written statement of certain of our officers certifying that to their knowledge we are in compliance with the indenture and the Notes, or else specifying any default.

Waiver of Default

The holders of a majority in principal amount of the Notes may waive any past defaults other than a default:

Merger or Consolidation

Under the terms of the indenture, we are generally permitted to consolidate or merge with another entity. We are also permitted to sell all or substantially all of our assets to another entity. However, we may not take any of these actions unless all the following conditions are met:

An assumption by any person of obligations under the Notes and the indenture might be deemed for federal income tax purposes to be an exchange of the Notes for new Notes by the holders thereof, resulting in recognition of gain or loss for such purposes and possibly other adverse tax consequences to the holders. Holders are urged to consult their tax advisors regarding the tax consequences of such an assumption.

Modification or Waiver

There are three types of changes we can make to the indenture and the Notes issued thereunder.

Changes Requiring Your Approval

First, there are changes that we cannot make to your Notes without your specific approval. The following is a list of those types of changes:

Changes Not Requiring Approval

The second type of change does not require any vote by the holders of the Notes. This type is limited to clarifications and certain other changes that would not adversely affect holders of the Notes in any material respect.

Changes Requiring Majority Approval

Any other change to the indenture and the Notes would require the following approval:

In each case, the required approval must be given by written consent. The holders of a majority in principal amount of all of the series of debt securities issued under the indenture, voting together as one class for this purpose, may waive our compliance with some of our covenants in that indenture. However, we cannot obtain a waiver of a payment default or of any of the matters covered by the bullet points included above under "- Changes Requiring Your Approval."

Further Details Concerning Voting

When taking a vote, we will use the following rules to decide how much principal to attribute to the Notes:

The Notes will not be considered outstanding, and therefore not eligible to vote, if we have deposited or set aside in trust money for their payment or redemption or if we or any affiliate of ours own any Notes. The Notes will also not be eligible to vote if they have been fully defeased.

We will generally be entitled to set any day as a record date for the purpose of determining the holders of the Notes that are entitled to vote or take other action under the indenture. However, the record date may not be earlier than 30 days before the date of the first solicitation of holders to vote on or take such action and not later than the date such solicitation is completed. If we set a record date for a vote or other action to be taken by holders of the Notes, that vote or action may be taken only by persons who are holders of the Notes on the record date and must be taken within eleven months following the record date.

Satisfaction and Discharge

The indenture will be discharged and will cease to be of further effect with respect to the Notes when:

Covenants

In addition to standard covenants relating to payment of principal and interest, maintaining an office where payments may be made or securities can be surrendered for payment and related matters, the following covenants will apply to the Notes:

Form, Exchange and Transfer of Certificated Registered Securities

If registered Notes cease to be issued in book-entry form, they will be issued:

Holders may exchange their certificated securities for Notes of smaller denominations or combined into fewer Notes of larger denominations, as long as the total principal amount is not changed and as long as the denomination is equal to or greater than $1,000.

Holders may exchange or transfer their certificated securities at the office of the trustee. We have appointed the trustee to act as our agent for registering Notes in the names of holders transferring Notes. We may appoint another entity to perform these functions or perform them ourselves.

Holders will not be required to pay a service charge to transfer or exchange their certificated securities, but they may be required to pay any tax (including a withholding tax) or other governmental charge associated with the transfer or exchange. The transfer or exchange will be made only if our transfer agent is satisfied with the holder's proof of legal ownership.

We may appoint additional transfer agents or cancel the appointment of any particular transfer agent. We may also approve a change in the office through which any transfer agent acts.

If any certificated securities of a particular series are redeemable and we redeem less than all the Notes, we may block the transfer or exchange of those Notes selected for redemption during the period beginning 15 days before the day we mail the notice of redemption and ending on the day of that mailing, in order to freeze the list of holders to prepare the mailing. We may also refuse to register transfers or exchanges of any certificated Notes selected for redemption, except that we will continue to permit transfers and exchanges of the unredeemed portion of any Note that will be partially redeemed.

If registered Notes are issued in book-entry form, only the depositary will be entitled to transfer and exchange the Notes as described in this subsection, since it will be the sole holder of the Notes.

Resignation of Trustee

The trustee may resign or be removed with respect to the Notes provided that a successor trustee is appointed to act with respect to the Notes. In the event that two or more persons are acting as trustee with respect to different series of indenture securities under the indenture, each of the trustees will be a trustee of a trust separate and apart from the trust administered by any other trustee.

Governing Law

The indenture and the Notes will be governed by and construed in accordance with the laws of the State of New York.

Indenture Provisions-Ranking

The Notes will be our direct unsecured obligations and will rank: