NYSE Holdings (formerly NYSE Euronext Holdings) is one of the world's largest exchange groups, with five regulated markets. It operates esteemed US exchanges such as the New York Stock Exchange (NYSE), NYSE Arca, NYSE MKT, NYSE Arca Options, and NYSE Amex Options. The network of exchanges trade more US equity volume than any other exchange group, with the NYSE specifically including some 90% of the Dow Jones Industrial Average companies and nearly 80% of the S&P 500 companies. The former NYSE Euronext was acquired in late 2013 by Intercontinental Exchange, which spun Euronext off into a separate entity and sold most of its shares in an IPO.