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SAN DIEGO--(BUSINESS WIRE)--Gossamer Bio, Inc. (NASDAQ: GOSS) (the “Company” or “Gossamer”), a biopharmaceutical company focused on the development and commercialization of seralutinib for the treatment of pulmonary arterial hypertension (PAH) and pulmonary hypertension associated with interstitial lung disease (PH-ILD), today announced that the initial conversion rate for its 7.50% Convertible Senior Secured First Lien Notes due 2030 (the “2030 Convertible Notes”) will be 5,347.5936 shares of t.

NEW YORK, May 30, 2026 (GLOBE NEWSWIRE) --

WHY: Rosen Law Firm, a global investor rights law firm, reminds purchasers of securities of Gossamer Bio, Inc. (NASDAQ: GOSS) between June 16, 2025 and February 20, 2026, inclusive (the “Class Period”), of the important June 1, 2026 lead plaintiff deadline.

SO WHAT: If you purchased Gossamer securities during the Class Period you may be entitled to compensation without payment of any out of pocket fees or costs through a contingency fee arrangement.

WHAT TO DO NEXT: To join the Gossamer class action, go to https://rosenlegal.com/submit-form/?case_id=61894 or call Phillip Kim, Esq. toll-free at 866-767-3653 or email [email protected] for information on the class action. A class action lawsuit has already been filed. If you wish to serve as lead plaintiff, you must move the Court no later than June 1, 2026. A lead plaintiff is a representative party acting on behalf of other class members in directing the litigation.

WHY ROSEN LAW: We encourage investors to select qualified counsel with a track record of success in leadership roles. Often, firms issuing notices do not have comparable experience, resources, or any meaningful peer recognition. Many of these firms do not actually handle securities class actions, but are merely middlemen that refer clients or partner with law firms that actually litigate the cases. Be wise in selecting counsel. The Rosen Law Firm represents investors throughout the globe, concentrating its practice in securities class actions and shareholder derivative litigation. Rosen Law Firm has achieved, at that time, the largest ever securities class action settlement against a Chinese Company. Rosen Law Firm was Ranked No. 1 by ISS Securities Class Action Services for number of securities class action settlements in 2017. The firm has been ranked in the top 4 each year since 2013 and has recovered hundreds of millions of dollars for investors. In 2019 alone the firm secured over $438 million for investors. In 2020, founding partner Laurence Rosen was named by law360 as a Titan of Plaintiffs’ Bar. Many of the firm’s attorneys have been recognized by Lawdragon and Super Lawyers.

DETAILS OF THE CASE: According to the lawsuit, defendants provided overwhelmingly positive statements to investors while, at the same time, disseminating false and misleading statements and/or concealing material adverse facts concerning the study design for Gossamer’s Phase 3 PROSERA study, particularly, controlling for the placebo response at the Latin American testing sites. When the true details entered the market, the lawsuit claims that investors suffered damages.

To join the Gossamer class action, go to https://rosenlegal.com/submit-form/?case_id=61894 or call Phillip Kim, Esq. toll-free at 866-767-3653 or email [email protected] for information on the class action.

No Class Has Been Certified. Until a class is certified, you are not represented by counsel unless you retain one. You may select counsel of your choice. You may also remain an absent class member and do nothing at this point. An investor’s ability to share in any potential future recovery is not dependent upon serving as lead plaintiff.

Follow us for updates on LinkedIn: https://www.linkedin.com/company/the-rosen-law-firm, on Twitter: https://twitter.com/rosen_firm or on Facebook: https://www.facebook.com/rosenlawfirm/.

Attorney Advertising. Prior results do not guarantee a similar outcome.

-------------------------------

Contact Information:

        Laurence Rosen, Esq.
        Phillip Kim, Esq.
        The Rosen Law Firm, P.A.
        275 Madison Avenue, 40th Floor
        New York, NY 10016
        Tel: (212) 686-1060
        Toll Free: (866) 767-3653
        Fax: (212) 202-3827
        [email protected]
        www.rosenlegal.com

New York, New York--(Newsfile Corp. - May 31, 2026) - WHY: Rosen Law Firm, a global investor rights law firm, reminds purchasers of securities of Gossamer Bio, Inc. (NASDAQ: GOSS) between June 16, 2025 and February 20, 2026, inclusive (the "Class Period"), of the important June 1, 2026 lead plaintiff deadline.

SO WHAT: If you purchased Gossamer securities during the Class Period you may be entitled to compensation without payment of any out of pocket fees or costs through a contingency fee arrangement.

WHAT TO DO NEXT: To join the Gossamer class action, go to https://rosenlegal.com/submit-form/?case_id=61894 or call Phillip Kim, Esq. toll-free at 866-767-3653 or email [email protected] for information on the class action. A class action lawsuit has already been filed. If you wish to serve as lead plaintiff, you must move the Court no later than June 1, 2026. A lead plaintiff is a representative party acting on behalf of other class members in directing the litigation.

WHY ROSEN LAW: We encourage investors to select qualified counsel with a track record of success in leadership roles. Often, firms issuing notices do not have comparable experience, resources, or any meaningful peer recognition. Many of these firms do not actually handle securities class actions, but are merely middlemen that refer clients or partner with law firms that actually litigate the cases. Be wise in selecting counsel. The Rosen Law Firm represents investors throughout the globe, concentrating its practice in securities class actions and shareholder derivative litigation. Rosen Law Firm has achieved, at that time, the largest ever securities class action settlement against a Chinese Company. Rosen Law Firm was Ranked No. 1 by ISS Securities Class Action Services for number of securities class action settlements in 2017. The firm has been ranked in the top 4 each year since 2013 and has recovered hundreds of millions of dollars for investors. In 2019 alone the firm secured over $438 million for investors. In 2020, founding partner Laurence Rosen was named by law360 as a Titan of Plaintiffs' Bar. Many of the firm's attorneys have been recognized by Lawdragon and Super Lawyers.

DETAILS OF THE CASE: According to the lawsuit, defendants provided overwhelmingly positive statements to investors while, at the same time, disseminating false and misleading statements and/or concealing material adverse facts concerning the study design for Gossamer's Phase 3 PROSERA study, particularly, controlling for the placebo response at the Latin American testing sites. When the true details entered the market, the lawsuit claims that investors suffered damages.

To join the Gossamer class action, go to https://rosenlegal.com/submit-form/?case_id=61894 or call Phillip Kim, Esq. toll-free at 866-767-3653 or email [email protected] for information on the class action.

No Class Has Been Certified. Until a class is certified, you are not represented by counsel unless you retain one. You may select counsel of your choice. You may also remain an absent class member and do nothing at this point. An investor's ability to share in any potential future recovery is not dependent upon serving as lead plaintiff.

Follow us for updates on LinkedIn: https://www.linkedin.com/company/the-rosen-law-firm, on Twitter: https://twitter.com/rosen_firm or on Facebook: https://www.facebook.com/rosenlawfirm/.

Attorney Advertising. Prior results do not guarantee a similar outcome.

-------------------------------

To view the source version of this press release, please visit https://www.newsfilecorp.com/release/299388

Source: The Rosen Law Firm PA

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LOS ANGELES, May 31, 2026 (GLOBE NEWSWIRE) -- The Schall Law Firm, a national shareholder rights litigation firm, reminds investors of a class action lawsuit against Gossamer Bio, Inc. (“Gossamer” or “the Company”) (NASDAQ: GOSS) for violations of §§10(b) and 20(a) of the Securities Exchange Act of 1934 and Rule 10b-5 promulgated thereunder by the U.S. Securities and Exchange Commission.

Investors who purchased the Company’s securities between June 16, 2025 and February 20, 2026, inclusive (the “Class Period”), are encouraged to contact the firm before June 1, 2026.

If you are a shareholder who suffered a loss, click here to participate.

We also encourage you to contact Brian Schall of the Schall Law Firm, 2049 Century Park East, Suite 2460, Los Angeles, CA 90067, at 310-301-3335, to discuss your rights free of charge. You can also reach us through the firm's website at www.schallfirm.com, or by email at [email protected].

The class, in this case, has not yet been certified, and until certification occurs, you are not represented by an attorney. If you choose to take no action, you can remain an absent class member.

According to the Complaint, the Company made false and misleading statements to the market. Gossamer concealed adverse facts about the design of its Phase 3 PROSERA study, especially regarding controls for placebo response at certain testing sites. Based on these facts, the Company’s public statements were false and materially misleading throughout the class period. When the market learned the truth about Gossamer, investors suffered damages.

Join the case to recover your losses

The Schall Law Firm represents investors around the world and specializes in securities class action lawsuits and shareholder rights litigation.

This press release may be considered Attorney Advertising in some jurisdictions under the applicable law and rules of ethics.        

CONTACT:

The Schall Law Firm
Brian Schall, Esq.,
www.schallfirm.com
Office: 310-301-3335
[email protected]

SOURCE:

 The Schall Law Firm

Gossamer Bio, Inc. Sued for Securities Law Violations - Contact the DJS Law Group to Discuss Your Rights - GOSS PR Newswire

LOS ANGELES, June 1, 2026

, /PRNewswire/ -- The DJS Law Group reminds investors of a class action lawsuit against Gossamer Bio, Inc. ("Gossamer" or "the Company") (NASDAQ: GOSS) violations of §§10(b) and 20(a) of the Securities Exchange Act of 1934 and Rule 10b-5 promulgated thereunder by the U.S. Securities and Exchange Commission.

Shareholders who purchased shares of GOSS during the class period listed are encouraged to contact the firm regarding possible lead plaintiff appointments. Appointment as lead plaintiff is not required to partake in any recovery.

CLASS PERIOD: June 16, 2025 to February 20, 2026
DEADLINE: June 1, 2026

CASE DETAILS: According to the Complaint, the Company made false and misleading statements to the market. Gossamer misled investors by concealing facts about issues with its Phase 3 PROSERA study. Based on these facts, Gossamer's public statements were false and materially misleading throughout the class period.

If you are a shareholder who suffered a loss, contact us to participate.

WHY DJS LAW GROUP? DJS Law Group's primary focus is to enhance investor return through balanced counseling and aggressive advocacy. We specialize in securities class actions, corporate governance litigation, and domestic/international M&A appraisals. Our clients are some of the largest and most sophisticated hedge funds and alternative asset managers in the world. The litigation claims of our clients are extraordinarily valuable assets that demand respect, focus, and results.

Join the case to recover your losses.

This press release may be considered Attorney Advertising in some jurisdictions under the applicable law and rules of ethics.

CONTACT:
David J. Schwartz
DJS Law Group
274 White Plains Road, Suite 1
Eastchester, NY 10709
Phone: 914-206-9742
Email: [email protected]

View original content:https://www.prnewswire.com/news-releases/gossamer-bio-inc-sued-for-securities-law-violations---contact-the-djs-law-group-to-discuss-your-rights--goss-302786661.html

SOURCE DJS Law Group LLP

, /PRNewswire/ -- A securities class action lawsuit has been filed against Gossamer Bio, Inc. (NASDAQ: GOSS) and an executive, seeking to represent investors who purchased or otherwise acquired Gossamer securities between June 16, 2025 and February 20, 2026.

The lawsuit follows Gossamer's bombshell announcement on February 23, 2026 that top-line results for its Phase 3 PROSERA study did not meet the primary endpoint (the change from baseline in six-minute-walk distance at week 24). The study evaluated seralutinib for the treatment of pulmonary arterial hypertension ("PAH").

The developments, including the trial failure and 80% stock drop, prompted national shareholder rights firm Hagens Berman to commence an investigation into the alleged pending claims that Gossamer violated federal securities laws. The firm encourages Gossamer investors who suffered substantial losses on Class Period GOSS investments to submit your losses now.

The firm also encourages persons with knowledge who may be able to assist the investigation to contact its attorneys.

View our latest video summary of the allegations: youtu.be/TOr_OsDdBXY

Class Period: June 16, 2025 – Feb. 20, 2026
Lead Plaintiff Deadline: June 1, 2026
Visit: www.hbsslaw.com/investor-fraud/goss
Contact the Firm Now: [email protected]
844-916-0895

Gossamer Bio, Inc. (GOSS) Securities Class Action:

The litigation is focused on the propriety of Gossamer's disclosures about the Phase 3 PROSERA trial design, including its patient recruitment protocol and site-level monitoring.

In the past, Gossamer has emphasized that serlutinib is a "potential first-in-class therapeutic[,]" which "represents the possibility of a multi-billion-dollar opportunity across multiple indications[.]"

As recently as mid-November 2025, the company's management cited the highly successful Merck Phase 3 STELLAR study of sotatercept for treating PAH. Gossamer's management said, "if you look at their data, the best performing region was Latin America, and we have actually more patients coming from those same geographies and same sites." Management also assured investors that "we have gone to the places where precedent studies have shown the greatest amount of efficacy, as well as having an entry criteria that is ensuring that we have patients who, we believe, will really show an improvement based upon, again background disease at week 24."

The complaint alleges that, unknown to investors, Gossamer knew of or recklessly disregarded the trial design issues with the Phase 3 PROSERA study and, instead, crafted a narrative assuring investors that it would meet its primary endpoint. Also unknown to investors, patients at the study's Latin America sites were largely heavily-treated and performing particularly well on placebo.

Investors' expectations were dashed on February 23, 2026. That day, Gossamer announced that PROSERA did not meet its primary endpoint and therefore efficacy was not statistically significant.

Management said during the conference call that day, "[t]he overall treatment effect and statistical parameters were materially diluted by an outsize placebo response and meaningful regional heterogeneity, which compressed the pool placebo-adjusted difference." More specifically, management revealed that in "Latin America, outsized placebo improvements materially compressed the pool treatment difference."

The market swiftly reacted, sending the price of Gossamer shares down by 80%.

After the Class Period, on April 9, 2026, the company revealed that since February 24, 2026 it has not met the minimum share bid price ($1) required for continued listing on the Nasdaq Global Select Market.

"We're focused on whether Gossamer may have misled investors about the PROSERA trial design, including patient entry criteria, as alleged in the pending lawsuit," said Reed Kathrein, the Hagens Berman partner leading the firm's investigation.

If you invested in Gossamer Bio and have substantial losses, or have knowledge that will assist the firm's investigation, submit your losses now.

If you'd like more information and answers to additional frequently asked questions about the Gossamer case and the firm's investigation, read more »

Whistleblowers: Persons with non-public information regarding Gossamer Bio should consider their options to help in the investigation or take advantage of the SEC Whistleblower program. Under the new program, whistleblowers who provide original information may receive rewards totaling up to 30 percent of any successful recovery made by the SEC. For more information, call Reed Kathrein at 844-916-0895 or email [email protected].

About Hagens Berman
Hagens Berman is a global plaintiffs' rights complex litigation firm focusing on corporate accountability. The firm is home to a robust practice and represents investors as well as whistleblowers, workers, consumers and others in cases achieving real results for those harmed by corporate negligence and other wrongdoings. Hagens Berman's team has secured more than $2.9 billion in this area of law. More about the firm and its successes can be found at hbsslaw.com. Follow the firm for updates and news at @ClassActionLaw.

View original content to download multimedia:https://www.prnewswire.com/news-releases/goss-deadline-alert-hagens-berman-alerts-gossamer-bio-goss-investors-to-todays-lead-plaintiff-deadline-in-securities-class-action-302786572.html

SOURCE Hagens Berman Sobol Shapiro LLP

LOS ANGELES--(BUSINESS WIRE)---- $GOSS--GOSS Investors Have Opportunity to Lead Gossamer Bio, Inc. Securities Fraud Lawsuit with the Schall Law Firm.

NEW YORK, June 01, 2026 (GLOBE NEWSWIRE) -- Bronstein, Gewirtz & Grossman, LLC, a nationally recognized investor-rights law firm, announces that a class action lawsuit has been filed against Gossamer Bio, Inc. (NASDAQ: GOSS) and certain of its officers.

This lawsuit seeks to recover damages against Defendants for alleged violations of the federal securities laws on behalf of all persons and entities that purchased or otherwise acquired Gossamer securities between June 16, 2025 and February 20, 2026, both dates inclusive (the “Class Period”). Such investors are encouraged to join this case by visiting the firm’s site: bgandg.com/GOSS.

Gossamer Case Details

The Complaint alleges that, throughout the Class Period, Defendants made materially false and misleading statements and/or failed to disclose that:

while publicly touting overwhelmingly positive results to investors, Defendants concealed material adverse facts regarding the design of the Company’s Phase 3 PROSERA study, including their failure to adequately control for placebo response at the Latin American testing sites; and 
as a result of the foregoing, Gossamer’s securities traded at artificially inflated prices, causing Plaintiff and other Class members to purchase shares at inflated levels. What's Next for Gossamer Investors?

A class action lawsuit has already been filed. If you wish to review a copy of the Complaint, you can visit the firm’s site: bgandg.com/GOSS. or you may contact Peretz Bronstein, Esq. or his Client Relations Manager, Nathan Miller, of Bronstein, Gewirtz & Grossman, LLC at 917-590-0911. If you suffered a loss in Gossamer you have until June 1, 2026, to request that the Court appoint you as lead plaintiff. Your ability to share in any recovery doesn't require that you serve as lead plaintiff.

No Cost to Gossamer Investors

We, Bronstein, Gewirtz & Grossman LLC, represent investors in class actions on a contingency fee basis. That means we will ask the court to reimburse us for out-of-pocket expenses and attorneys’ fees, usually a percentage of the total recovery, only if we are successful.

Why Bronstein, Gewirtz & Grossman, LLC for Gossamer Securities Class Action?

Bronstein, Gewirtz & Grossman, LLC is a nationally recognized firm that represents investors in securities fraud class actions and shareholder derivative suits. Our firm has recovered hundreds of millions of dollars for investors nationwide. More at www.bgandg.com

"Our practice centers on restoring investor capital and ensuring corporate accountability, which serves to uphold the essential integrity of the marketplace," said Peretz Bronstein, Founding Partner of Bronstein, Gewirtz & Grossman, LLC.

Follow us for updates on LinkedIn, X, Facebook, or Instagram.

Contact Info

Peretz Bronstein, Esq. or Nathan Miller
Bronstein, Gewirtz & Grossman, LLC
917-590-0911 | [email protected]

Attorney advertising.
Prior results do not guarantee similar outcomes.

NEW YORK--(BUSINESS WIRE)---- $GOSS #Bio--Faruqi & Faruqi, LLP, a leading national securities law firm, is investigating potential claims against Gossamer Bio, Inc. (“Gossamer” or the “Company”) (NASDAQ: GOSS) and reminds investors of the June 1, 2026 deadline to seek the role of lead plaintiff in a federal securities class action that has been filed against the Company.Faruqi & Faruqi is a leading national securities law firm with offices in New York, Pennsylvania, California and Georgia. The firm has.

SAN DIEGO--(BUSINESS WIRE)--Gossamer Bio, Inc. (NASDAQ: GOSS) (the “Company” or “Gossamer”), a biopharmaceutical company focused on the development and commercialization of seralutinib for the treatment of pulmonary arterial hypertension (PAH) and pulmonary hypertension associated with interstitial lung disease (PH-ILD), today announced that it has extended the early tender date (as extended, the “Extended Early Tender Date”) until 5:00 p.m., New York City time, on June 2, 2026 with respect to.