GOSS 8-K: Q3 2025 results press release furnished, Exhibit 99.1

Rhea-AI Filing Summary

Gossamer Bio (GOSS) furnished a Form 8-K announcing it issued a press release reporting financial results for the quarter ended September 30, 2025. The press release is included as Exhibit 99.1.

The company noted that the information in this item, including Exhibit 99.1, is being furnished and not filed under the Exchange Act and is not subject to Section 18 liabilities, nor incorporated by reference except as specifically stated. The report was signed by Bryan Giraudo, Chief Financial Officer and Chief Operating Officer.

8-K Event Classification

2 items: 2.02, 9.01

2 items

Item 2.02 Results of Operations and Financial Condition Financial

Disclosure of earnings results, typically an earnings press release or preliminary financials.

Item 9.01 Financial Statements and Exhibits Exhibits

Financial statements, pro forma financial information, and exhibit attachments filed with this report.

Understanding 8-K Material Events →

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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): November 5, 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 2.02 Results of Operations and Financial Condition.

On November 5, 2025, Gossamer Bio, Inc. (the “Company”) issued a press release reporting its financial results for the quarter ended September 30, 2025. The full text of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K.

In accordance with General Instruction B.2 of Form 8-K, the information contained or incorporated herein, including the press release attached as Exhibit 99.1, shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed to be incorporated by reference into any filing under the Securities Act of 1933, as amended (the “Securities Act”), or the Exchange Act, whether made before or after the date hereof, except as expressly set forth by specific reference in such filing to this Current Report on Form 8-K.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits.

Exhibit Number						Description
99.1						Press Release dated November 5, 2025
101						Cover Page Interactive Data File (embedded within the Inline XBRL document)

1

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: November 5, 2025						By:			/s/ Bryan Giraudo
									Bryan Giraudo
									Chief Financial Officer and Chief Operating Officer

2

FAQ

What did GOSS announce in this 8-K?

Gossamer Bio furnished a press release reporting financial results, attached as Exhibit 99.1.

Which period do the results cover for GOSS?

The results cover the quarter ended September 30, 2025.

Where can I read GOSS’s detailed quarterly results?

They are in the press release furnished as Exhibit 99.1 to the 8-K.

Is the GOSS press release considered 'filed' with the SEC?

No. It is furnished, not filed, and not subject to Section 18 of the Exchange Act.

Who signed the GOSS 8-K?

It was signed by Bryan Giraudo, Chief Financial Officer and Chief Operating Officer.

What is GOSS’s trading symbol and exchange?

The common stock trades as GOSS on the Nasdaq Global Select Market.