中文摘要：

发布澄清公告是上市公司应对市场传闻的重要途径。澄清公告能否有效应对市场传闻呢？本文针对这一主题展开研究，并进一步探讨了如何提高澄清效力。结论表明，有效市场假说在传闻澄清问题上没有得到支持，投资者对澄清公告反应不足。研究还发现，内容详细的澄清公告有助于消除传闻影响，股价在公告后30日内得以恢复；内容简略的澄清公告则可能造成无法挽回的后果，公告后60日内股价下跌幅度依然保持在4％的水平。本文研究是对行为金融理论的拓展，其结论一方面提示企业面对市场传闻应进行详细澄清，另一方面也为投资者提供了获得超额利润的投资策略。

英文摘要：

Clarification announcements are often used to rebut market rumors. Can clarificationseffectively cope with rumors？ The paper carries out a study on this issue and discusses how to improve the efficacy of clarification announcements. It arrives the following findings, the results do not support EMH for clarification announcements are undervalued by market. In addition, the author find that detailed clarifications will help to cope with rumors, and the prices will completely revert in 30 trading days. However, brief clarifications may cause severe consequences, and the fall of prices remains --4% after 60 trading days. This research expands theories of behavioral finance and the conclusion has important applications. On the one hand, it prompts public companies to clarify in detail when facing market rumors; on the other hand, it provides a profitable investment strategy for investors.