Finance professor Robert Battalio was interviewed for a Wall Street Journal story about an SEC economist's study indicating that brief delays in stock trading such as those offered by IEX’s exchange help protect ordinary investors from ultrafast traders. Read the full story here.
Other factors could explain why trading costs declined over the period that Mr. Hu examined, including the fact that stock prices were going up. Stock prices are a part of the ratio for calculating trading costs, and as they rise, that ratio would fall, said Robert Battalio, a finance professor at the University of Notre Dame.
"It's an interesting study, but there are other factors that need to be ruled out," Mr. Battalio said.