Informed and uninformed traders at work: evidence from the French market

The impact that informed and uninformed agents have on market prices is crucial for informational issues in financial markets. Informed trades are associated with institutional operators while uninformed trades are executed on behalf of retail investors. Using high-frequency data from Euronext Paris, I estimate a model where I take into account traders' identities at transaction level. The results show that when the identities of the traders are different on the two sides of the market, stock prices follow the direction indicated by institutional agents. This means that when the buyer is an informed operator and the seller is a retail one, the former transmits a positive pressure to the market. Conversely, when the seller is an institutional agent and the buyer is an uninformed one market prices depress. There is no significant effect when the agent types are the same on both market sides. Since traders' identities are concealed in Euronext Paris, the last part of the paper discusses the informational content implicitly provided by observed market variables. Institutional trading is found to increase throughout the day, whereas no evidence of informed trading is found during specific time periods of the continuous auction, except for the first thirty minutes of the day where there are more uninformed trades. Institutional trading is more common during periods of low price changes and high frequency of transactions. Price variations show that informed agents are usually able to trade at better price conditions. Finally, the tick-test algorithm strongly confirms that informed traders always act as initiators of market transactions