Welcome to our dedicated page for Gossamer Bio SEC filings (Ticker: GOSS), a comprehensive resource for investors and traders seeking official regulatory documents including 10-K annual reports, 10-Q quarterly earnings, 8-K material events, and insider trading forms.
The Gossamer Bio, Inc. (GOSS) SEC filings page on Stock Titan provides access to the company’s regulatory disclosures as a Nasdaq-listed issuer. Gossamer Bio is a late-stage, clinical biopharmaceutical company focused on developing and commercializing seralutinib for pulmonary arterial hypertension (PAH) and pulmonary hypertension associated with interstitial lung disease (PH‑ILD), and its filings offer detailed insight into this strategy.
Through current reports on Form 8‑K, Gossamer Bio reports material events such as quarterly financial results, stockholder meeting outcomes, and significant transactions. Recent 8‑K filings have described results of operations and financial condition, approval of amendments to its 2019 Incentive Award Plan, and the option agreement and plan of merger that grant Gossamer Bio the right to acquire Respira Therapeutics and its pulmonary hypertension candidate RT234. These documents outline share issuances, potential milestone payments, and other key terms.
Investors can also use this page to locate references to the company’s incentive equity plans, employment inducement awards, and stockholder voting results, which appear in filings related to annual meetings and compensation arrangements. While Forms 10‑K and 10‑Q are not reproduced here, they are accessible through EDGAR and provide comprehensive information on research and development expenses, collaboration revenue, cash resources, and risk factors tied to seralutinib and the broader pipeline.
Stock Titan enhances these filings with AI-powered summaries that explain the significance of each document in clear language. Users can quickly understand the main points of lengthy reports, track how new equity issuances affect capital structure, and see how clinical and business milestones are reflected in Gossamer Bio’s regulatory record. Real-time updates ensure that new 8‑K, 10‑Q, 10‑K, and Form 4 insider transaction filings for GOSS are surfaced as they are posted to EDGAR, helping users follow the company’s evolving disclosure history.
Gossamer Bio EVP Christian Waage reported a one-time stock option repricing and related option grants and cancellations. Effective as of March 19, 2026, the company approved an option repricing that reduced the exercise price of certain outstanding options to $0.45 per share under its 2019 Incentive Award Plan.
On that date, Waage received multiple new stock option awards with an exercise price of $0.45 covering an aggregate of 2,065,584 shares of common stock, while an equal number of higher-priced options with exercise prices ranging from $0.838 to $2.88 per share were surrendered to the issuer.
All other terms of the repriced options, including vesting schedules and expiration dates through 2036, remain in effect and continue to be tied to Waage’s ongoing service with Gossamer Bio.
Gossamer Bio, Inc. filed a Post-Effective Amendment (POS AM) converting its shelf registration to a non-automatic Form S-3 and provides a prospectus for the offering of up to $200.0 million of common stock, preferred stock, debt securities, warrants and units, to be sold from time to time after the effective date. The prospectus states that specific terms and amounts will be set in prospectus supplements and that offerings may be made through underwriters, dealers, agents or directly. The prospectus also discloses clinical updates: Phase 3 PROSERA topline showed a placebo-adjusted improvement in 6MWD of 13.3 meters (p = 0.0320), which missed the prespecified alpha of 0.025; the company plans to engage the FDA, including requesting a Type C meeting. Enrollment in the Phase 3 SERANATA study for PH-ILD was paused in February 2026.
Gossamer Bio reported widening losses and a setback in its lead pulmonary hypertension program. For 2025, total revenue was $48.5 million, down from $114.7 million in 2024, while net loss increased to $170.4 million, or $0.75 per share.
The Phase 3 PROSERA trial of seralutinib in pulmonary arterial hypertension narrowly missed its prespecified statistical threshold on the primary endpoint, though several subgroup and secondary measures favored seralutinib. The company paused enrollment in the Phase 3 SERANATA study and implemented a workforce reduction to align spending.
Cash, cash equivalents and marketable securities were $136.9 million at December 31, 2025, and Gossamer expects this to fund operations into the first quarter of 2027. The balance sheet showed total stockholders’ equity turning negative, at -$122.8 million, reflecting accumulated losses.
Gossamer Bio is a clinical-stage biopharma focused on seralutinib, an inhaled kinase inhibitor for pulmonary arterial hypertension (PAH) and pulmonary hypertension associated with interstitial lung disease (PH‑ILD). The company aims to become a leader in pulmonary hypertension treatments.
In the Phase 3 PROSERA study in PAH, seralutinib achieved a placebo‑adjusted six‑minute walk distance gain of 13.3 meters at Week 24 (p = 0.0320), missing the prespecified alpha threshold, but showed stronger effects in intermediate‑ and high‑risk patients and in connective tissue disease‑associated PAH. Gossamer is analyzing the dataset, engaging the FDA on potential regulatory paths, and advancing NDA‑readiness, with a potential approval action date anticipated by year end 2027 if an NDA is submitted and accepted.
The company entered a global collaboration with Chiesi, from which it will receive $160 million and share U.S. development and commercialization for PAH and PH‑ILD, while Chiesi leads outside the United States and in additional indications. Gossamer has paused enrollment in the SERANATA Phase 3 PH‑ILD trial to reassess strategy and continues open‑label extension studies. It also holds an option on RT234, an inhaled, on‑demand PDE5 inhibitor that could re‑enter clinical development as early as 2027, and is evaluating options to strengthen its capital structure, including its outstanding convertible notes and potential additional financings.
Gossamer Bio, Inc. filed a Post-Effective Amendment No. 1 to its Form S-3 to register up to $200.0 million of securities in the aggregate, including common stock, preferred stock, debt securities, warrants and units. The amendment states it is being filed because the company expects it will no longer be a "well-known seasoned issuer." The prospectus permits offers "from time to time after the effective date" and requires a prospectus supplement for terms and amounts of each offering. The filing also discloses the company’s Nasdaq symbol (GOSS) and a March 16, 2026 last reported sale price of $0.456 per share.
683 Capital Management, LLC and related reporting persons reported beneficial ownership in Gossamer Bio. As of March 2, 2026, the reporting persons beneficially owned 8,000,000 shares of common stock plus warrants exercisable for 4,331,304 shares, totaling 12,331,304 shares, or 5.23% of common stock on the basis described in the filing. The filing states the 4,331,304 warrants are currently exercisable and that voting and dispositive power over these securities is shared among the reporting persons.
The percentage uses an outstanding share base of 231,456,247 common shares as of October 31, 2025, plus the 4,331,304 exercisable-warrant shares, per the disclosure.
Gossamer Bio, Inc. received an amended Schedule 13D from New Enterprise Associates–affiliated entities led by Growth Equity Opportunities 18 VGE, LLC, updating their ownership in the company’s common stock.
On February 23, 2026, GEO completed open‑market public sales totaling 17,093,034 shares of Gossamer Bio common stock at a weighted average price of $0.3906 per share, with trade prices ranging from $0.3320 to $0.6363 per share.
After these transactions, as of February 23, 2026 GEO is the record owner of 1,000,000 shares and may be deemed to beneficially hold an additional 3,065,134 shares underlying GEO warrants, for total GEO‑related beneficial ownership of 4,065,134 shares, or 1.7% of Gossamer Bio’s outstanding common stock. That percentage is based on 234,521,381 shares, including 231,456,247 shares outstanding as of October 31, 2025 plus the GEO warrants. Voting and dispositive power over these shares is reported as shared among GEO, affiliated NEA entities, and several individual managers, each of whom disclaims beneficial ownership beyond shares held of record.
Gossamer Bio reported topline Phase 3 PROSERA results for seralutinib in pulmonary arterial hypertension. The trial did not meet its primary endpoint, with a Hodges‑Lehmann placebo‑adjusted improvement in six‑minute walk distance of 13.3 meters at Week 24 and a p‑value of 0.0320 versus a prespecified α of 0.025.
All four key secondary endpoints, including NT‑proBNP reduction, clinical improvement, time‑to‑clinical worsening and REVEAL Lite 2 risk score, numerically favored seralutinib, with especially strong effects in prespecified intermediate‑ and high‑risk patients and in connective tissue disease–associated PAH. Seralutinib was generally well tolerated, though liver enzyme elevations and cough were more frequent than with placebo.
The company plans to meet with the U.S. FDA to discuss a potential development path and is pausing enrollment in the SERANATA Phase 3 study while it assesses PROSERA, including regional differences in placebo response and forthcoming CT functional respiratory imaging substudy data.
Gossamer Bio, Inc. received an updated large-holder disclosure from Octagon Capital. Octagon Capital Advisors LP, Octagon Investments Master Fund LP, and Ting Jia jointly report beneficial ownership of 15,141,425 Gossamer Bio common shares, representing 6.5% of the outstanding stock.
This stake includes 13,915,371 common shares held by the Master Fund and warrants to purchase up to 1,226,054 additional shares at an exercise price of $2.04 per share, expiring on July 24, 2028. The ownership percentage is based on 231,456,247 shares outstanding as of October 31, 2025, plus the warrant shares.
The reporting persons state that the securities were acquired and are held in the ordinary course of business, and not for the purpose of changing or influencing control of Gossamer Bio.