Italian drugmaker Chiesi Farmaceutici SpA has agreed to buy U.S. biotech KalVista Pharmaceuticals for roughly $1.9 billion, its largest deal ever. The deal will see Chiesi launch a tender offer at $27 per share, representing a 40 % premium to KalVista’s Tuesday close. The transaction follows board approvals from both sides.

KalVista specializes in rare‑immune‑disease therapies, a fit that Chiesi’s EVP for Global Rare Diseases, Giacomo Chiesi, says will strengthen its rare‑disease portfolio. The $27 cash price translates into a 36 % premium over the company’s 30‑day volume‑weighted average, underscoring the premium investors are willing to pay for niche biologics.

Lazard will advise Chiesi, while Ropes & Gray LLP handles legal matters. KalVista’s counsel includes Centerview Partners, Jefferies, Kirkland & Ellis, and Fenwick & West. The deal is slated for completion in the third quarter, potentially reshaping the rare‑disease market and expanding Chiesi’s reach into high‑margin biologic therapies.

Investors will watch how the $1.9 billion purchase affects Chiesi’s earnings and cash flow, given the premium paid and the integration costs of a U.S. biopharma. Analysts expect the acquisition to lift Chiesi’s rare‑disease revenue base by roughly 20 % once the new products reach the market, boosting long‑term profitability.