Slow and fast markets

Informed traders need liquidity in order to profit from their private information. Markets provide liquidity and are compensated by the information released through trading. Fast markets provide access to a limit order book. Slow markets provide execution in an auction-based trading floor. Hybrid markets combine both execution venues. It is shown here that the overall efficiency of a hybrid market is determined by its fast component. The introduction of a trading floor does not generate more informed trading, only takes trading away from the fast market. Trading floors are thus inherently competitive to the fast market. We provide conditions that determine the competitiveness of a trading floor with respect to a fast market.