Pfizer has become Ireland's biggest foreign direct investment employer, with more than 5,000 employees, after it completed a $68 billion takeover of another pharmaceuticals giant, Wyeth.
The deal was announced nine months ago but closed yesterday following regulatory approval from competition authorities.
Both companies are major employers in Ireland and between them have operations at 13 separate locations.
Pfizer employs 2,100 people in Cork and Dublin and is best known for making Viagra.
Wyeth, which specialises in animal as well as human health, employs more than 3,000 people at locations in Dublin, Sligo Limerick and Kildare.
The merger is expected to lead to up to 20,000 job losses around the world. The combined entity will have annual sales of close to $70 billion. It has yet to be determined whether there will be job losses in Ireland as a result of the deal.
