After 220 years, a stock-trading concern that started under a buttonwood tree in lower Manhattan is getting taken over by a high-tech futures trader from the Deep South.

The merger of Atlanta's InterContinental Exchange with the Big Board's parent company NYSE Euronext, comes after the NYSE has spent decades working to modernise its offerings. The rise of electronic trading and alternate venues like "dark pools" for swapping shares has thinned the ranks of floor traders, making the physical location of the New York Stock Exchange more of a symbol of stock trading than a hub of it.