The authors examine forty-seven stocks that voluntarily left the American Stock Exchange from 1992 through 1995 and listed on the NASDAQ . They find that both effective and quoted spreads increase by about 100 percent after listing on the NASDAQ. These spread changes are consistent across stocks. In contrast, excess returns are positive when firms announce a switch from the American Stock Exchange to the NASDAQ. The authors are unable to explain this apparent contradiction.

We examine 47 stocks that voluntarily left the American Stock Exchange from 1992 through 1995 and listed on the Nasdaq. We find that both effective and quoted spreads increase by about 100 percent after listing on the Nasdaq. These spread changes are consistent across stocks. In contrast, excess returns are positive when firms announce a switch from The American Stock Exchange to the Nasdaq. We are unable to explain this apparent contradiction.

We examine 47 stocks that voluntarily left the American Stock Exchange from 1992 through 1995 and listed on the Nasdaq. We find that both effective and quoted spreads increase by about 100 percent after listing on the Nasdaq. These spread changes are consistent across stocks. In contrast, excess returns are positive when firms announce a switch from The American Stock Exchange to the Nasdaq. We are unable to explain this apparent contradiction.

Nasdaq's Small Order Execution System (SOES) allows orders to be submitted by computer, thereby assuring rapid execution at quoted prices. We examine trading in the 20 largest Nasdaq stocks around the time of a rule change that reduced the largest SOES trades from 1000 to 500 shares. We show that SOES trades contain information about short-term price movements and that SOES trading declined dramatically with the rule change. However, quoted and effective spreads were unaffected by the rule change.