The Activity of High Frequency Traders

Abstract

We examine the role of high-frequency traders (HFT) in price discovery and price efficiency. Overall HFT facilitate price efficiency by trading in the direction of permanent price changes and in the opposite direction of transitory pricing errors on average days and the highest volatility days. This is done through their marketable orders. In contrast, HFT liquidity-supplying non-marketable orders are adversely selected in terms of the permanent and transitory components as these trades are in the direction opposite to permanent price changes and in the same direction as transitory pricing errors. HFT predicts price changes in the overall market over short horizons measured in seconds. HFT is correlated with public information, such as macro news announcements, market-wide price movements, and limit order book imbalances.