Merck & Co., Inc., d.b.a. Merck Sharp & Dohme (MSD) outside the United States and Canada, is an American multinational pharmaceutical company and one of the largest pharmaceutical companies in the world. Merck is incorporated in New Jersey.
The company was established in 1891 as the United States subsidiary of the German company Merck, which was founded in 1668 by the Merck family. Merck & Co. was expropriated by the US government during World War I and subsequently established as an independent American company in 1917. While it operates as Merck & Co. in the United States and Canada, the original Merck based in Darmstadt holds the rights to the Merck name everywhere else. Merck & Co. is the world's seventh largest pharmaceutical company by market capitalization and revenue. Its headquarters is located in Kenilworth, New Jersey. The company ranked No. 78 in the 2018 Fortune 500 list of the largest United States corporations by total revenue.
Merck & Co. publishes The Merck Manuals, a series of medical reference books for physicians, nurses, technicians, and veterinarians. These include the Merck Manual of Diagnosis and Therapy, the world's best-selling medical reference. The Merck Index, a compendium of chemical compounds, was formerly published by Merck & Co. before being acquired by the Royal Society of Chemistry in 2012.