Gossamer Bio secures up to $250 million private placement tied to seralutinib milestones

Gossamer Bio announced on August 21, 2026 that it signed a securities purchase agreement with new and existing institutional investors for a private placement structured to deliver aggregate gross proceeds of up to approximately $250 million, before deducting placement agent fees and estimated offering expenses¹. The company said the financing follows its recent reacquisition of worldwide rights to seralutinib and comes ahead of a planned NDA submission in September 2026.¹

The placement is built in stages. It includes $150 million of committed capital, made up of about $25 million funded at the initial closing and roughly $125 million funded at a second closing tied to FDA acceptance of the seralutinib NDA in PAH.¹ That second tranche depends on the investors' obligations to fund the second closing remaining subject to the NDA acceptance milestone occurring in 2026 and the satisfaction of other customary closing conditions.¹

Beyond the committed capital, at the second closing investors will also receive warrants exercisable upon FDA approval of seralutinib in PAH, which if exercised in full for cash at $0.187 per share would provide up to approximately $100 million in additional gross proceeds.¹

Investors named include EcoR1 Capital, 683 Capital Partners, LP, RA Capital Management, Coastlands Capital, Samsara BioCapital and Rock Springs Capital, among others.¹ Leerink Partners and Cantor are acting as joint placement agents.¹

On use of proceeds, the company said it expects net proceeds from the initial closing plus the committed second-closing capital, combined with existing cash resources, to fund operations into 2028.¹ The company must also seek shareholder sign-off: Gossamer will seek stockholder approval required under Nasdaq listing rules for share issuance tied to the warrants and preferred stock conversion at a special meeting to be held after the initial closing.¹ The initial closing is expected around August 24, 2026.