中文摘要：

基于2006年至2012年A股证券市场的澄清公告，运用内容分析法收集澄清传闻样本，应用事件研究法和Heckman两阶段模型对上市公司发布公告澄清正面和负面传闻的效果以及传闻来源和澄清公告特征对其影响进行实证分析，探索澄清公告的辟谣效果及其影响因素。研究结果表明，对于正面传闻，澄清公告具有辟谣的效果；对于负面传闻，澄清公告不仅无法辟谣，反而起反作用。相对于非权威媒体发布的正面传闻而言，通过权威媒体发布的正面传闻更难以辟谣；相对于发布名义性澄清公告而言，通过发布技术性澄清公告能更有效地对正面传闻进行辟谣；但就负面传闻而言，没有得到显著的结果。研究结果为系统评价上市公司澄清公告的作用提供经验证据，并为上市公司如何发布澄清公告提供新思路。

英文摘要：

Based on the clarification announcements of Chinese A-share stock market from 2006 to 2012, we collect rumor clarifi- cation samples by the method of content analysis. We employ the Event Study and Hockman Two-stagn Model to empirically ana- lyze the effectiveness of clarification announcements for denying positive and negative rumors and explore the effects of rumor sources and clarification announcements＇ characteristics on the effectiveness. The results show that, for the positive rumors, clar- ification announcements play a denying role; hut for the negative rumors, clarification announcements exert an adverse effect in- stead of playing a denying role. In addition, it is more difficult to deny the positive rumors that are announced by authoritative media than by inanthoritative media. Compared with ceremonial clarification announcements, technical clarification announce- ments are more effective in denying the positive rumors, while for the negative rumors, there is no significant result. The empiri- cal results provide anecdotal evidence for systematically evaluating the effectiveness of listed companies＇ clarification announce- ments and new ideas to listed companies on how to release clarification announcements.