The theories of the microstructure en able us to analyze the way an equity market is working to give us the right directions to be taken and answer the following questions: According to which criteria can we evaluate the performance of a an exchange structure, in this case, the continuous electronic system? What are its effects on the quality of a young emerging market in terms of liquidity and informational efficiency? The objective of this research is the empirical analysis of the role of the continuous electronic exchange system on an emerging market. This research is elaborated around a microstructural analysis of an equity market, which are studied in a continuous exchange system driven by orders. We continue then with an event study applied to the Tunis Stock Exchange in order to check the effects on the performance of the market of the microstructural changes carried out by introducing the new continuous system NCS. This event was associated with a short-term negative market liquidity appreciation at the announcement of the transition to the electronic system, while the impact was positive in the medium and long term.