The Gossamer Bio, Inc. class action lawsuit was filed on behalf of those who purchased or otherwise acquired Gossamer Bio, Inc. (“Gossamer”) (NASDAQ: GOSS) securities between June 16, 2025 and February 20, 2026, inclusive (the “Class Period”). Captioned Daniel Kinnamon v. Gossamer Bio, Inc., No. 26-cv-02016 (S.D. Cal.), the Gossamer class action lawsuit alleges that Gossamer and/or certain of its officers and/or directors violated federal securities laws by making false or misleading statements and/or omitted to disclose material information.
If you lost money as a result of your Gossamer investment and want to find out more about this action and your rights, fill out the form on this page or contact attorney Jonathan Naji, Esq. of KTMC by calling (484) 270-1453 or via e-mail at info@ktmc.com.
COMPLAINT ALLEGATION SUMMARY:
Gossamer is a biopharmaceutical company focused on treatments for pulmonary hypertension (“PH”) associated with interstitial lung disease. One of its clinical stage drugs is called seralutinib, and Gossamer was evaluating its effectiveness in treating PH through the Phase 3 PROSERA study.
The complaint alleges that, throughout the Class Period, Defendants made materially false and/or misleading statements, as well as failed to disclose material facts about the company’s business, operations, and prospects. Specifically, Defendants misrepresented and/or failed to disclose that: (1) the Phase 3 PROSERA study suffered from design issues and failed to disclose that certain patients were already treated and low-risk; and (2) as a result of the foregoing, Defendants’ statements about the company’s business, operations, and prospects were materially false and misleading and/or lacked a reasonable basis at all relevant times.
WHY DID GOSSAMER’S STOCK DROP?
On February 23, 2026, Gossamer announced topline results for its Phase 3 PROSERA study, which shoed that it failed to meet its primary end point. On this news, Gossamer’s stock price fell more than 80% in a single day.
THE LEAD PLAINTIFF PROCESS:
The Private Securities Litigation Reform Act of 1995 permits any investor who purchased or acquired Gossamer securities during the Class Period to seek appointment as lead plaintiff in the Gossamer class action lawsuit. A lead plaintiff is a representative party that acts on behalf of other class members in directing the litigation. In order to be appointed lead plaintiff, the Court must determine that the class member’s claim is typical of the claims of other class members, and that the class member will adequately represent the class. Your ability to share in any recovery is not, however, affected by the decision whether or not to serve as a lead plaintiff. Filling out the online form above or communicating with any counsel is not necessary to participate or share in any recovery achieved in this case. Any member of the purported class may move the court to serve as a lead plaintiff through counsel of his/her choice, or may choose to do nothing and remain an inactive class member.
ABOUT KESSLER TOPAZ MELTZER & CHECK, LLP:
Kessler Topaz Meltzer & Check, LLP (KTMC) is a leading U.S. plaintiff-side law firm focused on securities-fraud class actions and global investor protection. The firm represents individual investors as well as institutions, such as major pension funds, asset managers, and international investors. KTMC has led some of the largest recoveries in securities litigation and has been recognized by peers and the legal media with numerous accolades, including The National Law Journal’s Plaintiff’s Hot List and Trailblazers in Plaintiffs' Law, BTI Consulting Group’s Honor Roll of Most Feared Law Firms, The Legal Intelligencer’s Class Action Firm of the Year, Lawdragon’s Leading Plaintiff Financial Lawyers, and Law360’s Titans of the Plaintiffs Bar. The firm operates globally with offices in Pennsylvania and California. KTMC has recovered over $25 billion for our clients and the classes they represent.