French drugmaker Sanofi fell 2.3% on saying that if it bid for Dublin-headquartered biotech company Horizon Therapeutics, it would do so in cash.

Horizon, with a market capitalization of about $18 billion, is also in talks with Amgen Inc and Johnson & Johnson unit Janssen Global Services over potential takeover offers.

The biotech company, which makes drugs for rare, auto immune 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 Chemo Centryx 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 $1billion.

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 US 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 September 30, a growth of 37% from last year, while Krystexxa garnered $500 million, up 27% from the prior year.