<P> The Merck Group's US subsidiary Merck & Co. was nationalized by the US government in 1917 and re-established as an independent American company . Until the end of World War II, the company was led by George W. Merck . Merck & Co. hold the trademark rights to the "Merck" name in North America, while its former parent company retains the rights in the rest of the world . </P> <P> In 1929, H.K. Mulford Company merged with Sharp and Dohme, Inc . This company brought to the future Merck & Co, Inc vaccine technology, including immunization of cavalry horses in World War I and delivery of a diphtheria antitoxin in 1925 . </P> <P> In 1953, Merck & Co. merged with Philadelphia - based Sharp & Dohme, Inc., founded by Alpheus Phineas Sharp and Carl Friedrich Louis Dohme in 1845, becoming the largest US drugmaker . The merger combined Merck & Co.'s strength in scientific research and chemical manufacturing with Sharp & Dohme's sales and distribution system and its marketing expertise . The combined company kept the trade name Merck in the United States and Canada, and as Merck Sharp & Dohme (MSD) outside North America . In 1965 Merck & Co. acquired Charles E. Frosst Ltd. of Montreal, Canada (founded 1899) and created Merck - Frosst Canada, Inc., as its Canadian subsidiary and pharmaceutical research facility . Merck & Co. closed this facility in July 2010, and the company was renamed Merck Canada in 2011 . </P> <P> The company was incorporated in New Jersey in 1970 . It has an operating subsidiary, KBI Inc., which was originally formed as a joint venture with AstraZeneca . In November 1993, Merck & Co. completed a $6 billion purchase of Medco Containment Services Inc., one of the largest mail - order pharmacy and managed - care drug companies . Merck & Co. spun Medco off ten years later, and on August 20, 2003, Medco Health Solutions began trading on the New York Stock Exchange . (In 2012, Medco merged with, and became a wholly owned subsidiary of, Express Scripts Holding Co .) </P>

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