ImageneBio (IMA) updates prospectus for resale of 2.5M registered shares

Rhea-AI Filing Summary

ImageneBio, Inc. provides an updated prospectus supplement for the resale of up to 2,508,337 shares of common stock under its Form S-1 registration statement (No. 333-290108). The shares may be offered and sold from time to time by identified selling stockholders.

The supplement incorporates information from ImageneBio’s Quarterly Report on Form 10-Q filed on August 5, 2026, which is attached in relevant part. The company’s common stock trades on the Nasdaq Capital Market under the symbol IMA, and the last reported sale price was $5.71 per share on August 4, 2026.

The document emphasizes that investing in these securities involves a high degree of risk and directs readers to the “Risk Factors” section in the base prospectus and any amendments or supplements.

Key Figures

Shares registered for resale: 2,508,337 shares of common stock Par value per share: $0.001 per share Last reported sales price: $5.71 per share +3 more

6 metrics

Shares registered for resale 2,508,337 shares of common stock Shares covered by the prospectus and prospectus supplement for selling stockholders

Par value per share $0.001 per share Par value of ImageneBio common stock registered for resale

Last reported sales price $5.71 per share Nasdaq Capital Market closing price on August 4, 2026

Registration statement number 333-290108 Form S-1 registration statement referenced by the prospectus

Prospectus date April 2, 2026 Date of the base prospectus supplemented by this document

Prospectus supplement date August 5, 2026 Date of the prospectus supplement incorporating Form 10-Q information

Key Terms

prospectus supplement, selling stockholders, Registration Statement on Form S-1, Nasdaq Capital Market, +1 more

5 terms

prospectus supplement regulatory

"This prospectus supplement supplements the prospectus dated April 2, 2026"

A prospectus supplement is an additional document provided alongside a company's main offering details, offering updated or extra information about a specific financial product being sold. It helps investors understand the latest terms, risks, and details of the investment, similar to how an update or revision clarifies or expands on original instructions, ensuring they have current and complete information before making a decision.

selling stockholders financial

"resale or other disposition from time to time by the selling stockholders identified"

Selling stockholders are existing owners of a company's shares who are offering some or all of their holdings for sale, often as part of a public offering or secondary transaction. For investors this matters because such sales increase the number of shares available to buy, can signal how confident current owners are about future prospects, and may put short-term pressure on the stock price similar to more tickets being released for a popular event.

Registration Statement on Form S-1 regulatory

"forms a part of our registration statement on Form S-1 (No. 333-290108)"

A registration statement on Form S-1 is a detailed filing a company submits to the U.S. securities regulator to register new shares for public sale; it includes a plain-language prospectus, financial statements, business description and risk factors. For investors it matters because it provides the official, comprehensive blueprint of the offering — like an owner’s manual — allowing buyers to assess risks, inspect financial health and compare valuation before deciding to invest.

Nasdaq Capital Market market

"Our Common Stock is listed on the Nasdaq Capital Market under the ticker symbol"

The Nasdaq Capital Market is a platform where smaller, emerging companies can list their shares for trading by investors. It provides these companies with access to funding and visibility, helping them grow, much like a local marketplace where new vendors can introduce their products to potential customers. For investors, it offers opportunities to discover early-stage companies with growth potential.

Risk Factors financial

"risks and uncertainties described in the section titled “Risk Factors” beginning on page 6"

Risk factors are elements or conditions that could cause an investment's value to decrease or lead to potential losses. They are like warning signs or obstacles that can affect the success of an investment, making it uncertain or more unpredictable. Recognizing risk factors helps investors understand the possible challenges and make more informed decisions.

Offering Details

secondary

Offering

Offering Type secondary

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Available on EDGAR 08/05/2026 - 04:52 PM Accepted by SEC EDGAR 08/05/2026 - 04:18 PM Learn about SEC filing dates

FAQ

What is ImageneBio, Inc. (IMA) registering in this prospectus supplement?

ImageneBio’s prospectus supplement covers the potential resale of 2,508,337 shares of common stock by selling stockholders. These shares are registered under Form S-1 and may be offered or disposed of from time to time as described in the base prospectus.

Who is selling the 2,508,337 shares of ImageneBio (IMA) common stock?

The selling stockholders identified in the prospectus may offer and resell up to 2,508,337 shares of ImageneBio common stock. The company itself is not described as the seller in this supplement; it facilitates registration for those holders’ potential dispositions.

How does this ImageneBio (IMA) prospectus supplement relate to the company’s Form 10-Q?

The supplement updates and supplements the base prospectus with information from ImageneBio’s Quarterly Report on Form 10-Q filed August 5, 2026. Relevant portions of that Form 10-Q are attached to provide investors with more current company disclosure.

On which exchange does ImageneBio (IMA) trade and what was the last price mentioned?

ImageneBio’s common stock trades on the Nasdaq Capital Market under the ticker IMA. The supplement notes a last reported sales price of $5.71 per share on August 4, 2026, providing a recent trading reference for the registered shares.

What risks does ImageneBio (IMA) highlight in connection with this resale offering?

The company states that investing in its securities involves a high degree of risk. Investors are directed to review the “Risk Factors” section beginning on page 6 of the base prospectus and similar sections in any prospectus amendments or supplements.

Is this ImageneBio (IMA) prospectus supplement standalone, or must it be read with the base prospectus?

The document is not complete on its own and must be read together with the April 2, 2026 base prospectus and any amendments or supplements. Where information conflicts, the prospectus supplement supersedes the corresponding disclosure in the base prospectus.

Filed Pursuant to Rule 424(b)(3)

Registration No. 333-290108

PROSPECTUS SUPPLEMENT

(To Prospectus dated April 2, 2026)

ImageneBio, Inc.

2,508,337 Shares of Common Stock

This prospectus supplement supplements the prospectus dated April 2, 2026 (the “Prospectus”), which forms a part of our registration statement on Form S-1 (No. 333-290108), as amended. This prospectus supplement is being filed to update and supplement the information in the Prospectus with certain information contained in our Quarterly Report on Form 10-Q, filed with the Securities and Exchange Commission on August 5, 2026 (the “Quarterly Report”). Accordingly, we have attached the Quarterly Report in relevant part to this prospectus supplement.

The Prospectus and this prospectus supplement relate to the proposed offer and resale or other disposition from time to time by the selling stockholders identified in this prospectus of 2,508,337 shares of common stock, par value $0.001 per share, (the “Common Stock”) of ImageneBio, Inc.

Our Common Stock is listed on the Nasdaq Capital Market under the ticker symbol “IMA.” On August 4, 2026, the last reported sales price of our Common Stock was $5.71 per share.

This prospectus supplement should be read in conjunction with the Prospectus, including any amendments or supplements to it, which is to be delivered with this prospectus supplement. This prospectus supplement is qualified by reference to the Prospectus, including any amendments or supplements thereto, except to the extent that the information provided by this prospectus supplement supersedes information contained in the Prospectus.

This prospectus supplement is not complete without, and may not be delivered or used except in conjunction with, the Prospectus, including any amendments or supplements to it.

Investing in our securities involves a high degree of risk. You should review carefully the risks and uncertainties described in the section titled “Risk Factors” beginning on page 6 of the Prospectus, and under similar headings in any amendments or supplements to the Prospectus.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities, or passed upon the accuracy or adequacy of this prospectus supplement. Any representation to the contrary is a criminal offense.

The date of this prospectus supplement is August 5, 2026