Les interruptions de cotation sur les marchés financiers : le cas du marché français

The aim of this work consists of a panoramic study of trading halts (trading reservations and suspensions) in the different world stock Exchanges. We draw up an inventory of the regulatory environments. We then compare the practices on the international financial markets. We show that the trading suspensions are the most common form. We observe that whatever the market, there is less than a suspension by equity per year and that most of them are information pending driven. We complete this panorama by offering a thorough analysis of the trading suspensions in Paris particularly in terms of frequency and duration. Our study on intraday data relates to the marketable securities members of the CAC40 over the period January 1998-December 2001. We show that the trading reservations outnumbered the suspensions and that there is a parallel between the frequency of the reservations and the high magnitude of the crises. From that angle, the 9Th 11 events caused the most significant crisis over the last years on the French financial markets. The purpose of the regulated halts on stock exchange markets is to spread out the information on the market and to protect the small shareholders interests. Thus, the main objective of trading halts is to reduce asymmetries of information and volatility. But empirically, it appears that those measures are anticipated by the investors. We show that that the trading suspensions in Euronext Bruxels and the reservations in Euronext Paris can decrease the volatility and the volume.