If you’ve watched CNBC’s Bob Pisani reporting from the floor of the New York Stock Exchange (NYSE) recently, you’ve probably noticed he has a lot more elbow room than in years past. In 2006, the NYSE had 3,000 traders and support staff on its floor, a number that had dwindled to just 1,500 by August 2008. Floor traders now account for just six percent of NYSE’s volume; the majority of the exchange’s trades are executed electronically.

The shift from trading floor to screen isn’t unique to the NYSE, and it is hardly a new phenomenon. Only a handful of trading floors still survive today, as electronic trading has come to dominate stock, futures, option, and currency trading worldwide.

The shift has, however, intensified in the past couple of years.