Gossamer Bio creates Series A-1 convertible preferred

Gossamer Bio, Inc. (GOSS) reported that on August 24, 2026 it amended its amended and restated certificate of incorporation in connection with the closing of a previously announced private placement.

Rhea-AI Filing Summary

Gossamer Bio, Inc. (GOSS) reported that on August 24, 2026 it amended its amended and restated certificate of incorporation in connection with the closing of a previously announced private placement. The company filed a Certificate of Designation of Preferences, Rights and Limitations of Series A-1 Convertible Preferred Stock with the Delaware Secretary of State, formally creating this preferred stock series.

The rights and preferences of the Series A-1 Convertible Preferred Stock are described in a prior report under Item 1.01 filed on August 21, 2026 and are further detailed in the Certificate of Designation attached as Exhibit 3.1 to this report.

8-K Event Classification

3 items: 1.01, 5.03, 9.01

3 items

Item 1.01 Entry into a Material Definitive Agreement Business

The company signed a significant contract such as a merger agreement, credit facility, or major partnership.

Item 5.03 Amendments to Articles of Incorporation or Bylaws; Change in Fiscal Year Governance

The company amended its charter documents, bylaws, or changed its fiscal year.

Item 9.01 Financial Statements and Exhibits Exhibits

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

Key Terms

Certificate of Designation, Series A-1 Convertible Preferred Stock, amended and restated certificate of incorporation

3 terms

Certificate of Designation regulatory

"the previously disclosed Certificate of Designation of Preferences, Rights and Limitations"

A certificate of designation is a formal document that spells out the specific rights and rules attached to a particular class or series of stock, usually preferred shares. Think of it as a rulebook or menu that lists dividend terms, liquidation priority, conversion or redemption rights and any special voting protections; investors use it to judge how much income, control or downside protection those shares will provide compared with other securities.

Series A-1 Convertible Preferred Stock financial

"Series A-1 Convertible Preferred Stock of the Company (the “Series A-1 Certificate"

A Series A-1 convertible preferred stock is a specific class of ownership that gives its holders priority over common shareholders for payments if a company is sold or shuts down, and typically pays a set dividend or return. It can be exchanged for ordinary shares under agreed terms, which can change ownership percentages and voting power. Investors watch these terms because they affect how much protection, income, and potential upside or dilution their stake carries—think of it as a special ticket that gets paid first and can be swapped for regular tickets.

amended and restated certificate of incorporation regulatory

"amended its amended and restated certificate of incorporation by filing"

A company’s amended and restated certificate of incorporation is an updated version of its foundational legal charter that replaces the older document and folds in all changes into one clear copy; it spells out corporate structure, classes of stock, shareholder rights and key governance rules. Investors care because it can change who controls the company, how votes are counted, what claims shareholders have on assets or dividends, and can introduce or remove protections against takeovers—like updating a house title after a major renovation to show who owns what and under what rules.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What did GOSS (Gossamer Bio, Inc.) change in its corporate documents?

Gossamer Bio, Inc. amended its amended and restated certificate of incorporation on August 24, 2026, by filing a Certificate of Designation that establishes the terms of its Series A-1 Convertible Preferred Stock with the Delaware Secretary of State.

Why did GOSS amend its certificate of incorporation on August 24, 2026?

The amendment was made in connection with the closing of a previously announced private placement. To support that transaction, Gossamer Bio filed a Certificate of Designation setting out the preferences, rights, and limitations of its Series A-1 Convertible Preferred Stock.

What new security did GOSS establish in this 8-K filing?

Gossamer Bio established a series of preferred stock called Series A-1 Convertible Preferred Stock. Its preferences, rights, and limitations are defined in the Certificate of Designation filed as Exhibit 3.1 and described in a prior report filed on August 21, 2026.

Where can investors find the detailed rights of the GOSS Series A-1 Convertible Preferred Stock?

The detailed rights are described in Item 1.01 of a report filed on August 21, 2026 and are qualified in their entirety by the Certificate of Designation, which is attached to this report as Exhibit 3.1.

Does this GOSS 8-K include financial statements or earnings data?

No. This report focuses on the amendment to the certificate of incorporation and the filing of the Series A-1 Convertible Preferred Stock Certificate of Designation. It lists no financial statements or earnings figures.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 08/26/2026 - 04:02 PM EDT Accepted by SEC EDGAR 08/26/2026 - 04:01 PM EDT Learn about SEC filing dates

0001728117FALSE12/3100017281172026-08-242026-08-2400017281172026-01-012026-12-31

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): August 24, 2026

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 5.03 Amendments to Articles of Incorporation or Bylaws; Change in Fiscal Year.

On August 24, 2026, in connection with the closing of its previously announced private placement, Gossamer Bio, Inc. (the “Company”) amended its amended and restated certificate of incorporation by filing with the Secretary of State of the State of Delaware the previously disclosed Certificate of Designation of Preferences, Rights and Limitations of Series A-1 Convertible Preferred Stock of the Company (the “Series A-1 Certificate of Designation”). The description of the rights and preferences of the Series A-1 Convertible Preferred Stock in Item 1.01 of the Current Report on Form 8-K filed by the Company with the Securities and Exchange Commission on August 21, 2026 is incorporated herein by reference, and such description is qualified in its entirety by reference to the Series A-1 Certificate of Designation, which is filed hereto as Exhibit 3.1.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits

Exhibit No						Description
3.1						Certificate of Designation of Preferences, Rights and Limitations of Series A-1 Preferred Stock
104						Cover Page Interactive Data File (embedded within the Inline XBRL document)

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: August 26, 2026						By:			/s/ Christian Waage
									Christian Waage
									Executive Vice President and General Counsel

Filing Exhibits & Attachments

4 documents

Other Documents

• EX-3.1 EX-3.1 93.4 KB
• EX-101 XBRL TAXONOMY EXTENSION SCHEMA DOCUMENT 1.8 KB
• EX-101 XBRL TAXONOMY EXTENSION LABEL LINKBASE DOCUMENT 22.0 KB
• EX-101 XBRL TAXONOMY EXTENSION PRESENTATION LINKBASE DOCUMENT 12.7 KB