“…Arnold, Hersch, Mulherin, and Netter (1999),Domowitz and Steil (1999), andPirrong (1999) stress the importance of assuming that exchanges are actually operative firms and argue that the industrial structure of market places cannot be explained by focusing on the demand side alone, as in financial market microstructure studies that concentrate on the characteristics of trading systems and the demand side of trading services, that is, the traders. It is equally important to know more about the provision of alternative technologies for trading services.4 The concept of network externalities is developed in the New Theory of Industrial Organization and represents an important field in economics, as it applies to a variety of industries, such as telecommunications, airlines, railroads, etc (Shy, 2001…”