完全涵盖了那些对市场造成明显影响或具有重要性的公司传闻。但是，我们认为这不会对研究结论造成较大影响。因为如果公司传闻不能造成明显的市场影响，说明市场并不关注它或它对市场不重要，既然是一个没有引起足够市场关注的不重要的公司传闻，也就说明其信息含量少。而且，在学术研究中，所选择的研究样本应是有重要影响的对象。所以，本研究中也没有必要包括那些影响小且不重要的传闻；（2）在研究股价同步性时，我们无法区分公司传闻和澄清公告对股价同步性的影响，也就是说，股价同步性的降低，很可能是公司传闻和澄清公告共同的结果。但是，本文样本中的公司传闻都对应着一个澄清公告，而且没有公司传闻就没有澄清公告，澄清公告是因公司传闻所致。也可以说，在一定程度上，澄清公告对股价同步性的影响也是公司传闻所致。因此，是否作此区分更大程度上是表述上的问题，而并不影响本文的结论；（3）指标的衡量。管理者和投资者之间的信息不对称衡量是一个十分困难的问题，因此，本文参照Agarwal and O’Hara（2007）的衡量方法，同时使用公司分析师跟踪的人数衡量管理者和投资者之间的信息不对称程度，以期降低这种指标衡量上的不足。
参考文献
Affleck-Graves, J., Callahan, C.M., and Chipalkatt, N., 2002, Earnings predictability, information asymmetry, and market liquidity, Journal of Accounting Research, 40 (3): 561-583.
Akerlof, G., 1970. The market for ‘lemons’: quality uncertainty and the market mechanism.Quarterly Journal of Economics 90, 629–650.
Agarwal,P and O’Hara., 2007, Information Risk and Capital Structuree. Working paper, SSRN.
Ali, A. and Hwang, L., 2000. Country-specific factors related to financial reporting and the value relevance of accounting data. Journal of Accounting Research 38, pp. 1–22.
Ball, R., A. Robin, and J. Wu, 2003. Incentives Versus Standards: Properties of Accounting Income in Four East Asian Countries. Journal of Accounting and Economics 36, 235-270.
Barth, M., Kasznik, R., McNichols, M., 2001. Analyst coverage and intangible assets. Journal of Accounting Research 39, 1–34.
Berle, A. A., & Means, G. C. The modern corporation and private property. New York: Harcourt, Brace, & World, 1968. (Original-ly published, 1932.)
Beaver, W., 1998. Financial reporting: an accounting revolution (3rd Edition ed.), Prentice-Hall, Englewood Cliffs, NJ.
Bushman, R., J. Piotroski, and A. Smith, 2004. What Determines Corporate Transparency? Journal of Accounting Research 42, 207-252.
Campbell J , M Lettau, B GMalkiel, Y Xu., 2001. Have Individual Stocks become more Volatile? An Emp irical Exp loration of Idiosyncratic Risk [ J ]. Journal of Finance, 56 (1) : 1- 43.
Chan K., Hameed A , 2006. Stock price synchronicity and analyst coverage in emerging markets. Journal of Financial Economics, 80 (1), pp. 115-147.
Chen Q, I Goldstein, W Jiang., 2007. Price Informativeness and Investment Sensitivity to Stock Price[J]. Review of Financial Studies, 20(3): 619-650.
Dasgupta, D., Gan, J., and Gao, N., 2008, Does lower R2 mean more informative stock prices? theory and evidence. Working paper, Hong Kong University of Science and Technology.
Dechow, P., Sloan, R., and Sweeney, A., 1995, Detecting earnings management. The Accounting Review 70:2-42.
Dierkens, Nathalie, 1991, Information asymmetry and equity issues, Journal of Financial and Quantitative Analysis, 26: 181–99.
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Durnev, A., Morck, R., Yeung, B., and Zarowin, P., 2003, Does greater firm-specific return variation mean more or less informed stock pricing? Journal of Accounting Research 41:797-836.
Fan, J., T. Wong, 2001. Corporate Ownership Structure and the Informativeness of Accounting Earnings in East Asia. Journal of Accounting and Economics 33, 401-426.
Frankle, R., and Li, Xu, , W., 2004, Characteristics of a firm's information environment and the information asymmetry between insiders and outsiders. Journal of Accounting and Economics 37, 229-259.
Grossman, S. and J. Stiglitz, 1980. On the Impossibility of Informationally Efficient Markets. American Economic Review 70, 393-408.
Hayek F A. , 1945. The Use of Knowledge in Society[J]. American Economic Review, 35(4): 519-530. Healy, P., and K. Palepu, 2001. Information Asymmetry, Corporate Disclosure, and the Capital Markets: A Review.
Ho, S. S. M. , and K. S. Wong. 2001. A Study of the Relationship between Corporate Governance Structures and the Extent of Voluntary Disclosure. Journal of InternationalAccounting, Auditing & Taxation 10 (2) : 139-156.
Hutton, A. P., Marcus, A. J., and Tehranian, H., 2009, Opaque financial report, R-square, and crash risk. Journal of Financial Economics. Forthcoming.
Jin, L., and Myers, S., 2006, R2around the world: new theory and new tests. Journal of Financial Economics 79: 257-292.
Lang, M., and R. Lundholm, 1993. Cross-Sectional Determinants of Analyst Ratings of Corporate Disclosures. Journal of Accounting Research 31, 246-271.
Lee, D. W., and Liu, M. H., 2007, Does more information in stock price lead to greater or smaller idiosyncratic return volatility? Working paper, University of Kentucky.
Marquardt, C.A, Wiedman C.I, 1998. Disclosure Policy, Information Asymmetry, and Liquidity in Equity Markets. contemporary Accounting Research 15, 505-537.
Morck, R., Yeung, B., and Yu, W., 2000, The information content of stock markets: why do emerging markets have synchronous stock price movements? Journal of Financial Economics 58:215-260.
Roll, R., 1988, R. Journal of Finance 43: 541-566.
Verrecchia, R., 1983. Discretionary Disclosure. Journal of Accounting and Economics 5, 179-194.
Welker, M., 1995. Disclosure Policy, Information Asymmetry, and Liquidity in Equity Markets. contemporary Accounting Research 11, 801-827.
Yohn Teri Lombardi, (1998), Information Asymmetry Around Earnings Announcements, Review of Quantitative Finance and Accounting, 11 (2): 165-182.
侯宇、叶冬艳，2008，“机构投资者、知情人交易和市场效率”，《金融研究》第4期。 李增泉，2005，“所有权结构与股票价格的同步性”，《中国会计与财务研究》第3期。
王亚平、刘慧龙、吴联生，2009，“中国证券分析师能提高资本市场效率吗？”《金融研究》第12期。 朱红军、何贤杰、陶林，2007，“中国证券分析师能提高资本市场效率吗？”《金融研究》第2期。
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Information Asymmetry, Rumors and Synchronicity of Stock Prices
Abstracts: This paper stutdys the relationship between the rumors and information asymmetry of manager-investors,and how the rumors influence the synchronicity of stock prices. structure．The empirical results indicate that the rumors are also directly related to the information asymmetry of manager-investors, and that the rumors as informal dislcosure information have significantly influenced the synchronicity of stock prices. The existing literature of dislcosure information always focus on the research of the formal disclosure informatio(eg. financial report),but neglects the research on the informal disclosure information. However, this result of this paper reveal the internal logic and the market consequence.
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Keywords: The Rumors, Synchronicity of Stock Prices, Information Asymmetry, Informal Disclosure Information
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