The differences between ECNs and Nasdaq market makers are used to formulate and test several hypotheses about the choice of trading venue and the importance of ECN trades in the price discovery process. Trades are more likely to occur on ECNs when spreads are narrow and when trading volume and...

We compare the execution quality of trades with market makers to trades executed on Electronic Communications Networks (ECNs). Average quoted, realized, and effective spreads are smaller for ECN trades than for market-maker trades even though ECN trades are more informative than trades with...

This paper examines the trading process outside of normal trading hours. Although after-hours trading volume is small, after-hours trades are more informative than trades during the day, and are associated with significant price discovery. Spread-related trading costs are also more than twice as...

We show that the consolidation of orders is important for producing efficient prices, especially during times of high liquidity demand. The NYSE's centralized opening call market performs better than Nasdaq's decentralized opening process on typical trading days. The NYSE is much better than...