GOSS

Business Context and Reporting Period

Company: Gossamer Bio, Inc. (GOSS)
Filing Type: Form 8-K (Current Report)
Date of Report: May 18, 2026
Principal Event: Commencement of an exchange offer and consent solicitation to restructure existing debt, alongside the announcement of clinical trial data and regulatory milestones for its lead candidate, seralutinib.

Key Financial Metrics and Capital Structure

Debt Restructuring (Exchange Offer):

• Existing Debt: 5.00% Convertible Senior Notes due 2027.
• New Debt: Up to $72.0 million in aggregate principal amount of 7.50% Convertible Senior Secured First Lien Notes due 2030 (New Convertible Notes).
• Equity Consideration: Up to 317,647,058 shares of Common Stock (or Prefunded Warrants) and up to 150,000,000 Purchase Warrants.
• Exchange Ratio (Early Tender): For each $1,000 of Existing Notes: $360 of New Notes, 1,588.2353 shares (or warrants), and 750 Purchase Warrants.
• Exchange Ratio (Late Tender): For each $1,000 of Existing Notes: $360 of New Notes and 1,588.2353 shares (or warrants); no Purchase Warrants.

Liquidity Covenants (New Notes):

• Initial Requirement: Maintain minimum liquidity of $40 million (tested monthly starting June 30, 2026).
• Reduction Triggers:
  • To $20 million upon completion of equity raises totaling at least $100 million.
  • To $10 million upon FDA acceptance of a New Drug Application (NDA) by December 1, 2026 (subject to the $100M raise).
  • To $0 upon completion of equity raises totaling at least $150 million (subject to the NDA filing).

Transaction Costs: Estimated fees and expenses of approximately $7.2 million (assuming 100% participation); $0.3 million paid as of March 31, 2026.

Financial Results: The filing references a press release for the quarter ended March 31, 2026, but does not provide specific revenue, profit, or cash flow figures within the text of this 8-K.

Material Changes and Corporate Actions

Debt Restructuring: The Company is replacing unsecured 5.00% notes with secured 7.50% notes and significant equity/warrant issuance. This includes a "springing maturity" date of March 2, 2027, if more than $4.0 million of the old notes remain outstanding.

Stockholder Proposals: The Company will seek approval for:

• Issuance of shares upon conversion of New Notes and exercise of warrants (exceeding 20% of current outstanding shares).
• Amendment to the Restated Certificate of Incorporation to increase authorized shares from 700 million to 4 billion.
• A reverse stock split (ratio between 1-for-10 and 1-for-150).
• Restatement of the 2019 Incentive Award Plan to increase share reserve by approximately 77 million shares (assuming 100% participation).

Transaction Support: Holders representing approximately 75.2% of the Existing Convertible Notes have entered into a Transaction Support Agreement to tender their notes and vote in favor of the proposals.

Outlook, Management Commentary, and Risks

Clinical and Regulatory Outlook:

• Pre-NDA Meeting: Confirmed in-person Type B meeting with the FDA scheduled for mid-June 2026 regarding seralutinib for Pulmonary Arterial Hypertension (PAH).
• NDA Submission: Expected in September 2026, contingent on the Pre-NDA meeting outcome.
• Approval Timeline: Potential FDA approval in Q3 2027 if the NDA is accepted for filing.

Clinical Data (PROSERA CT FRI Substudy):

• Reported statistically significant exploratory treatment effects in arterial, venous, and fibrosis-related parameters.
• Findings include reduced blood volume in larger arterial vessels and increased venous blood volume.
• Imaging changes correlated with favorable clinical outcomes (hemodynamics, NT-proBNP, 6-minute walk distance).

Risks and Contingencies:

• Transaction Completion: The Exchange Offer requires a minimum of 98% participation to close. Failure to meet this threshold could result in the transaction not occurring.
• Liquidity: The Company must meet strict liquidity covenants ($40M initially) or risk default on the new notes.
• Regulatory Uncertainty: FDA feedback may alter the development path or require additional capital.
• Dilution: Significant dilution is expected from the issuance of New Shares, Prefunded Warrants, and Purchase Warrants.

Investor Verification Checklist

• Participation Rate: Monitor the percentage of Existing Convertible Notes tendered to ensure the 98% minimum condition is met.
• Stockholder Approval: Verify the outcome of the Special Meeting regarding the reverse stock split, charter amendment, and equity plan restatement.
• Liquidity Position: Assess the Company's ability to maintain the $40 million minimum liquidity covenant starting June 30, 2026, and the likelihood of raising the required $100M-$150M in equity.
• FDA Interaction: Review the outcomes of the mid-June 2026 Pre-NDA Type B meeting for any changes to the NDA submission timeline or requirements.
• Financial Impact: Review the full Q1 2026 financial results (referenced in Exhibit 99.1) to understand current cash burn and runway.