We examine the impact on stock prices of a major upgrade to the New York Stock Exchange's trading environment. The upgrade improved information dissemination on the trading floor and reduced the latency in reporting trades and quotes. The portion of the upgrade that reduced latency for...

Andersen and Bondarenko's paper “VPIN and the Flash Crash” is essentially a comment on our 2011 Journal of Portfolio Management paper using our measure of order toxicity, VPIN. Andersen and Bondarenko dispute our empirical findings and argue that VPIN essentially does not work. This is...