[8-K] Gossamer Bio, Inc. Reports Material Event

Rhea-AI Filing Summary

Gossamer Bio, Inc. issued 2,500,000 shares of common stock to Prana on September 24, 2025 as consideration for a Company Merger Option. The Company agreed that, upon exercise of the Merger Option at closing, it would issue up to an additional 1,500,000 shares. The agreement also provides for cash and stock milestone payments following achievement of specified regulatory and sales milestones, including potential issuance of up to approximately 6,688,964 additional shares of common stock. The number of milestone shares to be issued will be calculated by dividing the applicable milestone obligation value by the average closing price on the Nasdaq Global Select Market for the thirty consecutive trading days ending two trading days before achievement of the milestone. The transactions are being made in reliance on Section 4(a)(2) of the Securities Act of 1933.

Positive

• Upfront consideration was delivered: 2,500,000 shares were issued to Prana on September 24, 2025.
• Contingent payments tied to milestones: Milestone payments are structured as cash and/or stock with a defined pricing formula for stock payments.
• Transparent pricing mechanism: Milestone stock amounts are calculated using a 30-day Nasdaq average ending two trading days prior to achievement.

Negative

• Potential dilution: The company agreed to issue up to an additional 1,500,000 shares at closing following exercise of the Merger Option.
• Further contingent dilution: The agreement allows issuance of up to approximately 6,688,964 additional shares upon achievement of milestones.
• Private placement reliance: Issuances are in reliance on Section 4(a)(2) of the Securities Act, indicating non-registered share issuance to counterparty stockholders.

Insights

M&A Specialist

TL;DR: Transaction grants Prana a merger option funded by an upfront equity issuance and contingent share and cash milestones.

The agreement documents a structured consideration package: a 2,500,000 share upfront issuance, up to 1,500,000 shares at closing following option exercise, and additional contingent payments tied to regulatory and sales milestones, including up to ~6,688,964 shares determined by a 30-day Nasdaq average price formula. These terms allocate risk between upfront equity and contingent payouts, tying future dilution to measurable outcomes and market price. The reliance on Section 4(a)(2) indicates private placement treatment for the issued shares.

Corporate Governance Expert

TL;DR: Agreement creates potential for material share issuance subject to objective milestone and pricing mechanics.

The filing discloses explicit issuance amounts and a defined mechanics for calculating milestone-share issuances using a 30-day Nasdaq average ending two trading days before achievement. This provides transparent share-issuance mechanics but also establishes a clear path to material dilution if milestones are achieved. The filing cites reliance on Section 4(a)(2), reflecting a non-registered securities issuance to the counterparty and related stockholders.

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): September 24, 2025

GOSSAMER BIO, INC.

(Exact name of Registrant as Specified in Its Charter)

Delaware			001-38796			47-5461709
(State or Other Jurisdiction of Incorporation)			(Commission File Number)			(IRS Employer Identification No.)

3115 Merryfield Row, Suite 120

San Diego, California, 92121

(Address of Principal Executive Offices) (Zip Code)

(858) 684-1300

(Registrant’s Telephone Number, Including Area Code)

N/A

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instructions A.2. below):

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class

Trading Symbol(s)

Name of each exchange on which registered

Common Stock, $0.0001 par value per share

GOSS

Nasdaq Global Select Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☐

Item 3.02. Unregistered Sales of Equity Securities.

On September 24, 2025, Gossamer Bio, Inc. (the “Company”) entered into that certain Option Agreement and Plan of Merger and Reorganization (the “Agreement”) pursuant to which the Company was granted the right, but in no circumstances the obligation, to acquire Respira Therapeutics, Inc. (“Respira”) via a merger (the “Company Merger Option”) with Prana Bio, Inc. (“Prana”), the 100% owner of Respira. The Company Merger Option will remain exercisable until the earlier of December 31, 2027 and the completion of certain development activities by Respira, unless earlier terminated in accordance with the terms of the Agreement.

Subject to certain terms and conditions set forth in the Agreement, the Company (i) issued 2,500,000 shares of the Company’s common stock, par value $0.0001 per share (the “Common Stock”) to Prana on September 24, 2025 as consideration for the grant of the Company Merger Option and (ii) agreed to (a) issue up to an additional 1,500,000 shares of Common Stock following the exercise of the Company Merger Option at the closing of the transaction and (b) upon the achievement of specified regulatory and sales milestones following the closing of the transaction, make cash and stock milestone payments, including the issuance of up to approximately 6,688,964 additional shares of Common Stock (provided that the number shares to be actually issued shall be calculated at the time of issuance by dividing the value of the applicable milestone obligation to be paid in stock by the average closing price of the Common Stock as reported on the Nasdaq Global Select Market for the thirty consecutive trading days ending on the second trading day prior to the date of achievement of the applicable milestone), in each case, to the current stockholders of Prana and the former stockholders of Respira in reliance upon Section 4(a)(2) of the Securities Act of 1933, as amended.

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

						GOSSAMER BIO, INC.
Date: September 25, 2025						By:			/s/ Bryan Giraudo
									Bryan Giraudo
									Chief Financial Officer and Chief Operating Officer

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FAQ

What shares were issued to Prana under the agreement?

The company issued 2,500,000 shares of common stock to Prana on September 24, 2025.

Are there additional shares payable upon closing or milestones?

Yes. Up to an additional 1,500,000 shares may be issued at closing following exercise of the Merger Option, and up to approximately 6,688,964 additional shares may be issued upon achievement of specified regulatory and sales milestones.

How is the number of milestone shares determined?

The milestone-share amount is calculated by dividing the value of the milestone obligation to be paid in stock by the average closing price of the common stock on the Nasdaq Global Select Market for the thirty consecutive trading days ending on the second trading day prior to achievement of the milestone.

Under what authority are the shares being issued?

The issuances to current stockholders of Prana and former stockholders of Respira are made in reliance on Section 4(a)(2) of the Securities Act of 1933.

When was the upfront issuance to Prana completed?

The upfront issuance of 2,500,000 shares to Prana was completed on September 24, 2025.