(The Wall Street Journal) -- John Thain led the New York Stock Exchange into the electronic age. Now it is up to his successor, Duncan Niederauer, to figure out what role the Big Board's old-fashioned floor trader will have.

Last week, as Big Board parent NYSE Euronext tapped Niederauer to succeed Thain as chief executive, two of the exchange's elite floor-trading "specialist" firms decided they were leaving, potentially throwing dozens of people out of work and raising the possibility of increased volatility on the exchange.