The Merck Group, branded and commonly known as Merck, is a German multinational pharmaceutical, chemical and life sciences company headquartered in Darmstadt, with about 56,000 employees and present in 66 countries.

The group includes around 250 companies; the main company is Merck KGaA in Germany. Merck was founded in 1668 and is the world's oldest operating chemical and pharmaceutical company, as well as one of the largest pharmaceutical companies in the world.

 

Merck operates in Europe, Africa, Asia, Oceania and the Americas. It has major research and development centres in Darmstadt, Boston, Tokyo and Beijing. 

According to en.wikipedia