NEW YORK — Stock exchange operator BATS Global Markets is buying Direct Edge to create the nation’s second-biggest stock exchange.
The new company will account for about 21 percent of the approximately 6.5 billion shares that are traded daily on exchanges, according to BATS. It would leapfrog over the Nasdaq and rank behind the New York Stock Exchange.
The combination is ‘‘an important milestone for the US equities market,’’ said BATS CEO Joe Ratterman, who will serve as CEO of the merged company.
The deal is part of a trend of consolidation among global stock exchanges. Technology has increased the speed at which trades are processed, but reduced the profit margins that exchanges can make on shares traded. Full story for BostonGlobe.com subscribers.