We analyse the intraday behaviour of high-frequency traders (HFTs) and its impact on aspects of market quality such as liquidity, price discovery and excess volatility. For that, we use a unique transactions data set for four UK stocks, over the period of a randomly selected week. Our data...

Using unique transactions data for individual high-frequency trading (HFT) firms in the UK equity market, we examine if the trading activity of individual HFT firms is contemporaneously and dynamically correlated with each other, and what impact this has on price efficiency. We find that HFT...