The New York Times report that the chief executive of the Nasdaq stock exchange, Robert Greifeld, on Friday shot back at criticism of how his exchange handled a three-hour halt in trading on Thursday afternoon.
Mr. Greifeld said in an interview on Friday morning that the breakdown on Thursday had been set off by another participant in the market, not something inside Nasdaq.
“We had an external environment happen,” he said. That problem, which Mr. Greifeld declined to describe more fully, caused issues with the data system that provides prices for recent trades in Nasdaq stocks. Nasdaq operates that system.
Mr. Greifeld, a longtime Nasdaq executive, said that the exchange needed to work on its “defensive driving” to deal better with mistakes by others.