Risk Aversion,Uncertain Information,and Market Efficiency

Abstract. We reexamine and extend tests of the uncertain information hypothesis (UIH) proposed by Brown, Harlow, and Tinic (1988, 1993). We find that their empirical results are sensitive to the sampling procedure employed and that their particular methodology does not sufficiently distinguish between event and nonevent periods. When the sampling procedure is modified to identify only relatively large, isolated events, the test results generally do not support the UIH. Instead, significant price shocks are consistently followed by short-lived price reversals. We observe this behavior following positive and negative events regardless of whether the event is classified as risk increasing or risk decreasing.     

Return and risk in initial public offerings of both shares and warrants

In the past few years there has been an increasing number of new issues of shares of common stock together with warrants intended to raise interest in initial public offerings of relatively young, growing firms. In this study we examine the pricing efficiency of stocks and warrants offered simultaneously to the public as a single unit. We present a model for evaluating the warrants in such offerings and test it empirically against data from the Tel-Aviv Stock Exchange, where such offerings have become standard. We find that the issued units are usually undervalued, allowing for significant abnormal positive returns. But, while the warrants are usually underpriced, the stocks are overpriced. Largely consistent with the evidence from other financial markets around the world, we also find abnormal negative rates of return in the long run.     

Dynamic analysis of stock return volatility in an integrated international capital market

This paper examines the dynamic behavior of the stock return volatility for Canada, Japan, Germany, and the United Kingdom. The evidence indicates that international stock return volatility is mainly influenced by the U.S. stock return volatility and the exchange rate volatility, supporting the international capital market integration hypothesis. There seems to be some correlation between stock return volatility and macroeconomic volatility, but the effect is relatively weaker. In addition to the economic fundamentals, the noise component is found to be time varying, confirming the AR(MA)CH specifications in the stock return models.     

股票价格均值回归理论研究综述

随机漫步理论认为股票的价格是不能预测的,许多实证检验的结果也支持了这一结论。但是,近年来均值回归理论对随机漫步理论提出了挑战。从长期来看,股票价格呈均值回归是必然的;均值回归具有不对称性;政府行为对股票的均值回归具有一定的影响。     

股权结构影响下的上市公司融资倾向研究

本文选取深沪两市的900家上市公司为样本,以2001-2004年的财务及相关数据为基础,从我国上市公司特殊的股权结构出发,运用一般描述性统计分析、偏相关分析、独立样本T检验等方法,分析我国上市公司股权结构与融资倾向之间的关系,以探究在相同市场环境中,不同的股权结构安排是否会导致其融资倾向的差异性。研究结果表明,股权结构对上市公司融资倾向具有显著的影响,不同股权结构安排下的公司有不同的融资倾向,特殊的股权结构是造成我国上市公司融资结构不合理的主要因素。     

我国股市与货币需求的相互影响分析及政策涵义

运用协整、弱外生性和因果关系检验对我国股票市场与货币需求的关系进行的实证研究发现,股市不影响M2的总量但影响其结构;M1对股市不产生直接影响,而M2对股市的直接影响处于有与无的临界状态;M1、M2均通过GDP对股市产生间接影响,但没有形成利率传导机制,我国股市是关于协整向量的弱外生变量.基于以上结论提出了相应的政策建议.     

R&D Progress, stock price volatility, and post-announcement drift: An empirical investigation into biotech firms

I investigate the effects of R&D progress on the dynamics of stock price volatility and the post announcement drift to provide insights into whether or not and how capital markets react to corporate R&D progress in the context of the biotech industry. I find both stock price volatility and the post announcement drift decrease in R&D progress. More importantly, the decrease is proportional to the increase in the drug development success rate driven by R&D progress. Findings suggest that R&D progress conveys useful risk-relevant information, and plays an important role in explaining stock price volatility change and market anomalies.     

Dynamic volatility and external security related shocks: The case of the Athens Stock Exchange

This paper analyses the impact of exogenous national security related shocks on the time-varying volatility structure of the Greek stock market. Alternative autoregressive conditional heteroscedastic models are estimated, in order to identify the best fit that adequately describes return volatility behavior, testing symmetric as well as asymmetric innovation responses. An external national security related shock factor is included as well as a military crisis dummy, in order to depict possible implications for the conditional variance. The empirical findings appear to support a statistically significant impact of both national security related factors on the Athens stock market returns.     

基于资本配置效率的资本市场发展与经济增长——以汽车制造业上市公司为例的实证研究

研究资本市场发展与经济增长的关系,是揭示资本市场对资本配置效率的一个重要研究视角。以汽车制造业上市公司为例,对投资增长与资本回报率之间关系的实证检验,发现我国股票市场的资本配置效率低下,并导致其促进经济增长的功能微弱。造成我国资本市场资本配置效率低下的直接原因是上市公司绩效的非稳定性和经营非持续性。因此,要实现我国资本市场引导资金流向、优化资源配置,促进经济增长作用的功能,必须提高上市公司业绩稳定性和经营持续性。     

Board Members and Company Value

This essay surveys research about the value of individual members of boards of directors. When directors join or exit corporate boards, company stock prices respond, often in magnitudes of 1% of firm value or more. Related research shows that when a significant event impacts the stock price of one company, the effects are transmitted to other companies that share board members in common with the primary company. Share price reactions are sensitive to variables such as a director’s occupation, independence, and professional qualifications. Together, this evidence suggests that a well-functioning market for directors might already exist, making direct regulation unnecessary and possibly counter-productive.