Competition on the Nasdaq and the growth of electronic communication networks

This paper examines the growth of electronic communication networks (ECNs) and their competitive impact on the Nasdaq. We find that the development of these alternative trading platforms is associated with tighter quoted, effective, and relative bid-ask spreads, greater depths, and less concentrated markets. Further, our results show that an increase in ECN trading may have caused some traditional market makers (wholesaler and national retail dealers) to exit the market for market making. Overall, our results suggest that ECNs provide a source of competition to traditional Nasdaq dealers.