PCX was one of the four United States exchanges to trade equity options and also the first to implement an electronic trading system. This exchange network organizes the trading of stock options between both individual and institutional investors. PCX had operations in San Francisco and Los Angeles, but these both closed in the early 2000 when it partnered with the Archipelago Exchange. The latter later merged with the New York Stock Exchange, and PCX transactions are now conducted on the NYSE Arca platform.