Purpose– The purpose of this paper is to consider competition’s issues between European market firms, such as Euronext, and multilateral trading facilities, following Markets in Financial Instruments Directive’s enforcement. This new domestic competition is adding to the existing international competition among financial centers. While diversification of local trading services can improve the international competitiveness of a financial center, the fragmentation of order flows can harm its attractiveness.Design/methodology/approach– The theoretical setting analyzes the interaction between heterogeneous who experiment network externalities, and heterogeneous local trading services providers (alternative platforms and incumbent) in an international context. The authors compare two forms of organizations of the market: a consolidated market, and a fragmented market with alternative platforms – in both cases, in competition with a foreign universe.Findings– The results of this study point out the importance of the trade-off between diversification and externalities. With alternative platforms entry, enhanced competition decreases fees and redistributes informed investors between the foreign market and the domestic one. The increase of domestic platforms’ number then has more complex effects on externalities (of information and liquidity). When the liquidity externalities are low, the diversification of financial platforms increases the number of investors on domestic centers. When liquidity externalities are not negligible, despite the decrease of fees, this same diversification orientates more informed investors to the foreign center.