The biotech company, with a market capitalization of about $18 billion, is in talks with Amgen Inc, Sanofi and Johnson & Johnson unit Janssen Global Services.

Horizon, which makes drugs for rare, autoimmune and severe inflammatory diseases, however, added there can be no certainty that any offer will be made.

The three firms have been active in deal-making this year.

Amgen acquired ChemoCentryx in a $4 billion deal in October, while J&J earlier this month announced a $16.6 billion bid for Abiomed.

Sanofi earlier this year completed the buyout of immuno-oncology company Amunix Pharmaceuticals for around $1 billion.

Amgen declined to comment on the talks, while Sanofi and Janssen Global were not immediately available.

Horizon expects over $4 billion in global annual peak sales for its biggest drug Tepezza, which is used to treat thyroid eye disease.

It has also estimated more than $1.5 billion in peak U.S. annual sales of its second largest drug Krystexxa, used for the treatment of gout that is not controlled by other medicines.

Tepezza had generated nearly $1.5 billion in the nine months ended Sept. 30, a growth of 37% from last year, while Krystexxa garnered $500 million, up 27% from the prior year.

(Reporting by Leroy Leo in Bengaluru; Editing by Sriraj Kalluvila)