Abstract: | Dual trading can have opposite effects: although competition between markets should induce dealers to offer cheaper transactions, market fragmentation could reduce market activity, liquidity, and exchange efficiency. This paper shows that for French stocks traded on the London Stock Exchange's SEAQ International (SEAQ–I), market activity decreases significantly in the Paris Bourse during UK bank holidays. Thus, SEAQ–I market makers seem to divert a new clientele to the Paris Bourse, increasing both market activity and the breadth of the Bourse's order book. Also, contrary to the fragmentation hypothesis, dual trading does not seem to increase information asymmetry. |