The New York Stock Exchange (NYSE), nicknamed the "Big Board", is a stock exchange based in New York City. It is the largest stock exchange in the world by dollar volume and, with 2,764 listed securities, has the second most securities of all stock exchanges. It was the second biggest stock exchange in the world in terms of company listings, second only to NASDAQ with 3,200 companies, before the Bombay Stock Exchange (BSE) of India consolidated to become the biggest stock exchange in the world with 4,800 company listings as of August 2007. As of December 31, 2006, the combined capitalization of all New York Stock Exchange listed companies was $25.0 trillion. The NYSE is operated by NYSE Euronext, which was formed by the NYSE's merger with the fully electronic stock exchange Euronext. The New York Stock Exchange trading floor is located at 11 Wall Street, and is composed of four rooms used for the facilitation of trading. A fifth trading room, located at 30 Broad Street, was closed in February 2007. The main building, located at 18 Broad Street between the corners of Wall Street and Exchange Place, was designated a National Historic Landmark in 1978.