The CEO of the New York Stock Exchange told CNBC Thursday that some of Thursday's trades in Procter & Gamble "will get taken off the table."
P&G , which dropped about $20 in a minute, traded as low as $39.37 at one point. "That $39 trade will not stand," said Duncan Niederauer. "I think it was just a few offers and there weren't many bids."
"This is the market structure we all signed up for," Niedermayer said. "Today we had to slow the market down. We also have the right to slow down the market as appropriate," he added.
"I don't think you are looking for one bank that traded the wrong number of shares," Niederauer said. "Electronic markets have a different business model."
The chief executive also had a prediction for Friday's market open: It's going to be "fairly ugly tomorow morning."