NYMEX stands for the New York Mercantile Exchange, according to Investopedia. As of 2015, the NYMEX is the largest physical commodity futures exchange in the world.
The New York Mercantile Exchange began in 1872 when a group of dairy merchants founded The Butter and Cheese Exchange of New York, explains Investopedia. In 1994, the NYMEX merged with the commodity exchange known as the COMEX. As a result of the merger, traders conduct business through two divisions: the NYMEX Division and the COMEX Division. The energy, platinum and palladium markets are within the NYMEX Division, and the markets for gold, silver, copper and other metals are within the COMEX Division.