Gossamer Bio completes exchange of 2027 convertible notes into secured notes

The exchange and what it changed

Gossamer Bio, Inc. (Nasdaq: GOSS) announced the final tender results of its exchange offer for its 5.00% Convertible Senior Notes due 2027. The company offered to exchange those notes for a pro rata share of up to $72.0 million of new 7.50% Convertible Senior Secured First Lien Notes due 2030. Eligible holders could also receive common stock or prefunded warrants, of which up to 317,647,058 shares were available, and holders who tendered early could also receive purchase warrants.

Holders of $181,052,000 of principal tendered their notes by 5:00 p.m. on June 2, 2026, the Extended Early Tender Date. The company and the Required Supporting Noteholders then cut the minimum tender condition from 98% of the principal to 90.5%. Early settlement occurred on June 4, 2026.

With that settlement, the company signed a supplemental indenture that removes substantially all restrictive covenants from the 2027 indenture, along with certain events of default and related provisions. That change applies to every note still outstanding under the indenture, not only to the notes that were exchanged. No additional notes were tendered by June 16, 2026, so $18,948,000 of principal remains outstanding.

Who is named

D.F. King & Co., Inc. is the exchange agent and information agent for the offer. The release names no other advisor, and it does not describe any new cash proceeds from the exchange. It also does not describe the collateral securing the new first-lien notes.

The seralutinib program

Gossamer is a clinical-stage company developing seralutinib for pulmonary arterial hypertension and for pulmonary hypertension associated with interstitial lung disease. The company's annual report, filed March 17, 2026, says that topline results from the Phase 3 PROSERA study were announced in February 2026. The company says it is completing in-depth analyses of that dataset, seeking FDA feedback on regulatory paths, and evaluating its strategic options while it strengthens its capital structure.

The annual report says the company believes seralutinib shows a risk-benefit profile that supports continued regulatory dialogue, based on PROSERA and the Phase 2 TORREY study. The annual report passage cited here does not say whether PROSERA met its primary endpoint. Whether to file a new drug application is still open, and the company says that decision depends on the PROSERA analyses and FDA feedback. If an NDA is submitted and accepted for substantive review, the company anticipates a potential approval action by the end of 2027, but it calls that timing subject to FDA feedback and other variables.

Revenue, losses and cash

Revenue was $48.5 million in 2025, against $114.7 million in 2024. Research and development expense rose to $174.1 million from $138.5 million. The net loss was $170.4 million in 2025, compared with $56.5 million in 2024. Cash used in operations was $171.3 million in 2025, compared with $3.5 million in 2024.

The filings cited here do not explain the jump in cash use. At the end of 2024 the company held $46.1 million in cash and cash equivalents and $248.4 million in short-term investments.

What the exchange leaves behind

Holders who did not tender still hold 2027 notes, and those notes no longer carry most of the covenants they had before the supplemental indenture. The new notes total up to $72.0 million, against $181,052,000 of tendered principal. Up to 317,647,058 shares of common stock were available under the offer, so existing shareholders face potential dilution if those equity securities are issued.

The annual report also says the company has paused SERANATA enrollment while it weighs the implications of PROSERA, and that it is evaluating alternatives for its outstanding convertible notes.

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