We empirically investigate the effect of option listing on the underlying stock market quality by examining the stock price duration dynamic, the liquidity and the informed trading activity around option listing. We use trade-to-trade data accounting for intraday seasonality and find evidence of less frequent trades and higher intraday seasonal liquidity after option listing. Our Log-ACD models, jointly with the informed trading activity results indicate no permanent change in the underlying market quality and reject the hypothesis of a permanent move of informed traders. Our findings suggest that a new arrival of informed traders could occur during the trading day as a seasonal feature. Robustness check tests confirm these results except for the low-volume stocks for which we find evidence of informed traders’ migration. Further tests show that the Euronext and Liffe merger in 2002 had an impact on the duration process and on its informational content.