Gossamer Bio's Phase 3 Trial Results Disappoint
Written by Emily J. Thompson, Senior Investment Analyst
Updated: Feb 23 2026
0mins
Should l Buy GOSS?
Source: Benzinga
Gossamer Bio's shares fell sharply, hitting a 52-week low, following disappointing results from its Phase 3 PROSERA trial for seralutinib, which showed significant but insufficient improvement in patient mobility.
The trial revealed that seralutinib led to a median change of +28.2 meters in Six-Minute Walk Distance (6MWD) at Week 24, failing to meet the predefined efficacy threshold. However, in a subgroup of patients with connective tissue disease-associated pulmonary arterial hypertension, the drug achieved a placebo-adjusted gain of +37.0 meters, indicating potential effectiveness. Gossamer plans to meet with the U.S. FDA to discuss future development for seralutinib while pausing enrollment in the SERANATA study to evaluate the impact of these results.
The market reacted negatively, with Gossamer Bio's shares plummeting by 77.12% to $0.59, reflecting investor disappointment and prompting analysts to lower their earnings expectations.
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Analyst Views on GOSS
Wall Street analysts forecast GOSS stock price to rise
4 Analyst Rating
3 Buy
1 Hold
0 Sell
Strong Buy
Current: 0.372
Low
10.00
Averages
12.33
High
15.00
Current: 0.372
Low
10.00
Averages
12.33
High
15.00
About GOSS
Gossamer Bio, Inc. is a late-stage, clinical biopharmaceutical company, which is focused on the development and commercialization of seralutinib for the treatment of pulmonary arterial hypertension and pulmonary hypertension associated with interstitial lung disease (PH-ILD). Seralutinib, also known as GB002, is an investigational inhaled, small-molecule, platelet-derived growth factor receptor (PDGFR), colony-stimulating factor 1 receptor (CSF1R), and c-KIT inhibitor, being evaluated in a Phase III clinical trial for the treatment of PAH. Seralutinib is designed to target the mechanisms that underlie pulmonary hypertension and to be delivered to the site of disease, via dry powder inhaler. Seralutinib is being evaluated in a Phase III clinical trial for the treatment of pulmonary arterial hypertension (PAH). Inhaled seralutinib, which is designed to act on both isoforms of the PDGFR, α and β, as well as the CSF1R and c-KIT pathways.
About the author
Emily J. Thompson
Emily J. Thompson, a Chartered Financial Analyst (CFA) with 12 years in investment research, graduated with honors from the Wharton School. Specializing in industrial and technology stocks, she provides in-depth analysis for Intellectia’s earnings and market brief reports.
Class Action Lawsuits Filed for Multiple Companies
- Gossamer Bio Lawsuit: Shareholders of Gossamer Bio have filed a class action lawsuit due to the company's failure to disclose critical clinical trial results from June 2025 to February 2026, with a lead plaintiff deadline of June 1, 2026, potentially impacting the company's reputation and stock price.
- New Era Energy Lawsuit: New Era Energy shareholders have initiated a class action lawsuit alleging that the company overstated project progress and engaged in fraudulent activities from November 2024 to December 2025, with the same deadline of June 1, 2026, which may lead to decreased investor confidence.
- Medpace Holdings Lawsuit: Shareholders of Medpace have filed a class action lawsuit due to the company's inaccurate business projections from April 2025 to February 2026, with a lead plaintiff deadline of June 5, 2026, potentially negatively affecting the company's future financing capabilities.
- Stellantis Lawsuit: Stellantis shareholders have initiated a class action lawsuit alleging that the company failed to accurately disclose the realities of the electric vehicle market from February 2025 to February 2026, with a lead plaintiff deadline of June 8, 2026, which may impact the company's competitiveness in the EV sector.
See More
Class Action Lawsuit Filed Against Gossamer Bio by Shareholders
- Class Action Initiation: Wolf Haldenstein Adler Freeman & Herz LLP has announced a class action lawsuit on behalf of shareholders who purchased Gossamer Bio (NASDAQ:GOSS) securities between June 16, 2025, and February 20, 2026, with a deadline for lead plaintiff applications set for June 1, 2026, highlighting significant concerns over the company's financial transparency.
- Allegations of Misrepresentation: The filed complaint alleges that throughout the class period, defendants made materially false and misleading statements and failed to disclose adverse facts regarding the company's business, operations, and prospects, indicating severe deficiencies in corporate governance and information disclosure.
- Clinical Trial Failure: On February 23, 2026, Gossamer disclosed that its Phase 3 PROSERA study of seralutinib for pulmonary arterial hypertension failed to meet its primary endpoint, resulting in an 80.3% stock price drop, which triggered a crisis of confidence among investors regarding the company's future.
- Law Firm's Background: Founded in 1888, Wolf Haldenstein Adler Freeman & Herz LLP boasts over 125 years of legal expertise in securities litigation, dedicated to pursuing justice for investors harmed by misrepresentations, showcasing its professionalism and reliability in protecting investor rights.
See More
Class Action Filed Against Gossamer Bio for Securities Violations
- Class Action Initiated: Bronstein, Gewirtz & Grossman, LLC has announced a class action lawsuit against Gossamer Bio, seeking damages for investors who purchased securities between June 16, 2025, and February 20, 2026, highlighting potential violations of federal securities laws.
- False Statements Allegations: The complaint alleges that Gossamer Bio made materially false and misleading statements during the class period, failing to disclose significant flaws in the design of its Phase 3 PROSERA study, which led investors to buy shares at artificially inflated prices.
- Investor Losses: The lawsuit claims that due to the failure to adequately control for placebo response at Latin American testing sites, Gossamer's securities traded at inflated levels, resulting in losses for investors, with the lawsuit aiming to recover these damages.
- Legal Fee Arrangement: The law firm operates on a contingency fee basis, meaning they will only seek reimbursement for expenses and attorney fees from the court if they are successful, thereby reducing the financial burden on investors pursuing the lawsuit.
See More
Gossamer Bio Investors Reminder for Upcoming Lawsuit Deadline
- Lawsuit Deadline: Investors must file a lead plaintiff motion by June 1, 2026, to participate in the class action regarding losses incurred from Gossamer Bio (NASDAQ:GOSS) securities purchased between June 16, 2025, and February 20, 2026.
- Stock Price Plunge: On February 23, 2026, Gossamer's stock plummeted by $1.71, or 80.3%, closing at $0.42 per share after the company disclosed that its Phase 3 PROSERA study failed to meet its primary endpoint, significantly harming investors.
- False Statements Allegation: The lawsuit alleges that throughout the class period, the company made materially false and misleading statements and failed to disclose critical information about the treatment of patients in Latin America, leading to misleading assessments of the company's prospects.
- Legal Consultation Channels: Investors can contact the Law Offices of Howard G. Smith via email or phone to learn about their rights and the process for participating in the lawsuit, ensuring their legal interests are protected.
See More
Class Action Reminder for New Era Energy and Gossamer Bio
- New Era Energy Lawsuit: A class action lawsuit against New Era Energy (NUAI) alleges that the company failed to disclose material facts regarding its Texas Critical Data Centers project from November 6, 2024, to December 29, 2025, resulting in significant investor losses, with a deadline of June 1, 2026, to apply as lead plaintiff.
- Gossamer Bio Lawsuit: A class action lawsuit against Gossamer Bio (GOSS) claims that the company made misleading statements regarding its Phase 3 PROSERA study between June 16, 2025, and February 20, 2026, with the same June 1, 2026, deadline for investors to seek lead plaintiff status.
- Law Firm Credentials: Holzer & Holzer, LLC, recognized as an ISS top-rated securities litigation firm from 2021 to 2025, is dedicated to vigorously representing shareholders and investors, having recovered hundreds of millions of dollars for victims of corporate misconduct since its inception in 2000.
- Investor Rights Advocacy: The firm encourages investors who purchased shares during the specified periods and suffered losses to contact their attorneys to understand their legal rights, ensuring they receive the necessary protection and support in the litigation process.
See More
Gossamer Bio Accused of Misleading Investors in Class Action
- Class Action Filed: Robbins LLP reminds shareholders that a class action has been initiated on behalf of investors who purchased Gossamer Bio (NASDAQ: GOSS) securities between June 16, 2025, and February 20, 2026, alleging the company misled investors regarding its PROSERA study, causing shareholders to buy securities at artificially inflated prices.
- Study Results Fail: On February 23, 2026, Gossamer announced that its Phase 3 PROSERA study failed to meet its primary endpoint, achieving only a +13.3 meter placebo-adjusted gain in six-minute walk distance (6MWD), which did not meet the required 0.025 alpha threshold, leading to a stock price drop of over 80% in a single day.
- Investor Confidence Eroded: The concealment of issues related to placebo response control in the study design severely undermined investor confidence, with the stock price plummeting from $2.13 per share on February 20, 2026, to $0.42 per share on February 23, reflecting a pessimistic outlook on the company's future prospects.
- Shareholder Action Guidance: Shareholders wishing to serve as lead plaintiffs in the class action must submit their papers by June 1, 2026, with Robbins LLP offering contingency fee representation, ensuring shareholders can potentially recover losses without upfront costs.
See More
Class Action Lawsuits Filed for Multiple Companies
- Gossamer Bio Lawsuit: Shareholders of Gossamer Bio have filed a class action lawsuit due to the company's failure to disclose critical clinical trial results from June 2025 to February 2026, with a lead plaintiff deadline of June 1, 2026, potentially impacting the company's reputation and stock price.
- New Era Energy Lawsuit: New Era Energy shareholders have initiated a class action lawsuit alleging that the company overstated project progress and engaged in fraudulent activities from November 2024 to December 2025, with the same deadline of June 1, 2026, which may lead to decreased investor confidence.
- Medpace Holdings Lawsuit: Shareholders of Medpace have filed a class action lawsuit due to the company's inaccurate business projections from April 2025 to February 2026, with a lead plaintiff deadline of June 5, 2026, potentially negatively affecting the company's future financing capabilities.
- Stellantis Lawsuit: Stellantis shareholders have initiated a class action lawsuit alleging that the company failed to accurately disclose the realities of the electric vehicle market from February 2025 to February 2026, with a lead plaintiff deadline of June 8, 2026, which may impact the company's competitiveness in the EV sector.
See More
Class Action Lawsuit Filed Against Gossamer Bio by Shareholders
- Class Action Initiation: Wolf Haldenstein Adler Freeman & Herz LLP has announced a class action lawsuit on behalf of shareholders who purchased Gossamer Bio (NASDAQ:GOSS) securities between June 16, 2025, and February 20, 2026, with a deadline for lead plaintiff applications set for June 1, 2026, highlighting significant concerns over the company's financial transparency.
- Allegations of Misrepresentation: The filed complaint alleges that throughout the class period, defendants made materially false and misleading statements and failed to disclose adverse facts regarding the company's business, operations, and prospects, indicating severe deficiencies in corporate governance and information disclosure.
- Clinical Trial Failure: On February 23, 2026, Gossamer disclosed that its Phase 3 PROSERA study of seralutinib for pulmonary arterial hypertension failed to meet its primary endpoint, resulting in an 80.3% stock price drop, which triggered a crisis of confidence among investors regarding the company's future.
- Law Firm's Background: Founded in 1888, Wolf Haldenstein Adler Freeman & Herz LLP boasts over 125 years of legal expertise in securities litigation, dedicated to pursuing justice for investors harmed by misrepresentations, showcasing its professionalism and reliability in protecting investor rights.
See More
Class Action Filed Against Gossamer Bio for Securities Violations
- Class Action Initiated: Bronstein, Gewirtz & Grossman, LLC has announced a class action lawsuit against Gossamer Bio, seeking damages for investors who purchased securities between June 16, 2025, and February 20, 2026, highlighting potential violations of federal securities laws.
- False Statements Allegations: The complaint alleges that Gossamer Bio made materially false and misleading statements during the class period, failing to disclose significant flaws in the design of its Phase 3 PROSERA study, which led investors to buy shares at artificially inflated prices.
- Investor Losses: The lawsuit claims that due to the failure to adequately control for placebo response at Latin American testing sites, Gossamer's securities traded at inflated levels, resulting in losses for investors, with the lawsuit aiming to recover these damages.
- Legal Fee Arrangement: The law firm operates on a contingency fee basis, meaning they will only seek reimbursement for expenses and attorney fees from the court if they are successful, thereby reducing the financial burden on investors pursuing the lawsuit.
See More
Gossamer Bio Investors Reminder for Upcoming Lawsuit Deadline
- Lawsuit Deadline: Investors must file a lead plaintiff motion by June 1, 2026, to participate in the class action regarding losses incurred from Gossamer Bio (NASDAQ:GOSS) securities purchased between June 16, 2025, and February 20, 2026.
- Stock Price Plunge: On February 23, 2026, Gossamer's stock plummeted by $1.71, or 80.3%, closing at $0.42 per share after the company disclosed that its Phase 3 PROSERA study failed to meet its primary endpoint, significantly harming investors.
- False Statements Allegation: The lawsuit alleges that throughout the class period, the company made materially false and misleading statements and failed to disclose critical information about the treatment of patients in Latin America, leading to misleading assessments of the company's prospects.
- Legal Consultation Channels: Investors can contact the Law Offices of Howard G. Smith via email or phone to learn about their rights and the process for participating in the lawsuit, ensuring their legal interests are protected.
See More
Class Action Reminder for New Era Energy and Gossamer Bio
- New Era Energy Lawsuit: A class action lawsuit against New Era Energy (NUAI) alleges that the company failed to disclose material facts regarding its Texas Critical Data Centers project from November 6, 2024, to December 29, 2025, resulting in significant investor losses, with a deadline of June 1, 2026, to apply as lead plaintiff.
- Gossamer Bio Lawsuit: A class action lawsuit against Gossamer Bio (GOSS) claims that the company made misleading statements regarding its Phase 3 PROSERA study between June 16, 2025, and February 20, 2026, with the same June 1, 2026, deadline for investors to seek lead plaintiff status.
- Law Firm Credentials: Holzer & Holzer, LLC, recognized as an ISS top-rated securities litigation firm from 2021 to 2025, is dedicated to vigorously representing shareholders and investors, having recovered hundreds of millions of dollars for victims of corporate misconduct since its inception in 2000.
- Investor Rights Advocacy: The firm encourages investors who purchased shares during the specified periods and suffered losses to contact their attorneys to understand their legal rights, ensuring they receive the necessary protection and support in the litigation process.
See More
Gossamer Bio Accused of Misleading Investors in Class Action
- Class Action Filed: Robbins LLP reminds shareholders that a class action has been initiated on behalf of investors who purchased Gossamer Bio (NASDAQ: GOSS) securities between June 16, 2025, and February 20, 2026, alleging the company misled investors regarding its PROSERA study, causing shareholders to buy securities at artificially inflated prices.
- Study Results Fail: On February 23, 2026, Gossamer announced that its Phase 3 PROSERA study failed to meet its primary endpoint, achieving only a +13.3 meter placebo-adjusted gain in six-minute walk distance (6MWD), which did not meet the required 0.025 alpha threshold, leading to a stock price drop of over 80% in a single day.
- Investor Confidence Eroded: The concealment of issues related to placebo response control in the study design severely undermined investor confidence, with the stock price plummeting from $2.13 per share on February 20, 2026, to $0.42 per share on February 23, reflecting a pessimistic outlook on the company's future prospects.
- Shareholder Action Guidance: Shareholders wishing to serve as lead plaintiffs in the class action must submit their papers by June 1, 2026, with Robbins LLP offering contingency fee representation, ensuring shareholders can potentially recover losses without upfront costs.
See More
