The Internet is widely used by listed companies to manage investor relations. Since January 2007, the French Financial Authority has required companies listed on Euronext-Paris to disclose all mandatory financial information via the Internet in order to enhance information transparency. This paper examines the impact of Internet-based disclosure on the French stock market by analyzing the relationship between information asymmetry and Internet disclosure practices. Extending previous studies on Web-based disclosure, a checklist of 40 items is developed to evaluate the level of Internet-based voluntary disclosure. Measuring information asymmetry by the spread and the probability of informed trading, we show that greater Web-based disclosure lowers information asymmetry in the French financial market.