Floor versus Screen Trading: Evidence from the German Stock Market

The last decade has witnessed a dramatic increase in both the number and the market share of screen-based trading systems. Electronic trading systems do offer lower operating costs and the possibility of remote access to the market. On the other hand, arguments based on the anonymity of electronic trading systems suggest that adverse selection may be a more severe problem and that, therefore, bid-ask spreads may be higher. The present paper addresses the issue of transaction costs in floor and computerized trading systems empirically. In Germany, floor and screen trading for the same stocks exist in parallel. Both markets are liquid and operate simultaneously for several hours each day. An analysis of the bid-ask spreads reveals that the electronic trading system is relatively less attractive for less liquid stocks. The market shares of the competing systems reveal a similar pattern. The market share of the electronic trading system is negatively related to the total trading volume of the stock, is positively related to the difference between spreads on the floor and in the screen trading system and is at least partially negatively related to return volatility. We further document that spreads in the electronic trading system respond more heavily to changes in return volatility and that the adverse selection component of the spread is larger. We discuss implications our results have for the design of electronic trading systems. JEL classification: G 10