An Examination of Alternative Factor Models in UK Stock Returns

This paper examines the mean-variance efficiency of a number offactor models in UK stock returns. The paper also explores, using theapproach of MacKinlay (1995), whether missing risk factors ornonrisk-based explanations best explain the pricing errors of thedifferent factor models. The evidence in the paper suggests that themean-variance efficiency of each factor model is rejected and missing riskfactors are unable to explain the pricing errors of any of the models.Some nonrisk-based explanations, which posit a wide spread in abnormalreturns, may be a more plausible source of explaining the pricing errorsof the factor models.     

Predictability of stock markets with disequilibrium trading

This paper analyses the predictability of a hypothetical market with freely negotiated prices on which exists a censoring of one-period returns which are in excess of an arbitrary level (‘floor’ and ‘ceiling’). It is shown that the expected value of returns (adjusted for drift) conditional on last period information regarding the censoring are equal to zero (and therefore the market is not predictable in mean) if there is no intertemporal spillover on the market. A simple simulation model is proposed and applied for the analysis of the effects of intertemporal and cross-spillovers resulting from quantity constraints. Statistical predictability tests are proposed, based on the corrected Student-t statistic of a regression of returns of some information concerning the previous censoring. An illustrative empirical analysis of six main time series of returns on the Warsaw Stock Exchange confirms their ex-ante, but not ex-post, predictability.     

Stock Price Adjustment to the Information in Dividend Changes

This paper examines abnormal stock returns in the three years surrounding relatively large changes in dividends announced during the 1971 to 1990 period. The main results are that statistically and economically significant negative post-announcement abnormal returns of 11% and 17% over the post-announcement year are found for firms which decrease dividends and those which omit their dividends. Firms resuming and firms increasing dividends do not exhibit significant abnormal returns, on average, over the post-announcement year. The pattern of lagged price adjustment to negative dividend change information differs from that reported for 'earnings surprise' firms in important respects. While the dividend change firms do exhibit returns behavior consistent with year-to-year returns momentum, differences in prior year returns do not explain the differences in returns over the post-announcement period.     

Do Stock Market Investors Overreact?

This paper investigates the evidence on the stock market overreaction hypothesis (ORH), which holds that, if stock prices systematically overshoot as a consequence of excessive investor optimism or pessimism, price reversals should be predictable from past price performance. The ORH stands in contradiction to the efficient markets hypothesis which is a cornerstone of financial economics. This study is unique in the overreaction literature because it is restricted to larger and better-known listed companies, whose shares are more frequently traded. This restriction more or less eliminates two alternative explanations to the overreaction hypothesis: it minimises the influence of bid-ask biases and infrequent trading, and reduces the possibility that reversals are primarily a small-firm phenomenon. The paper also investigates a third alternative explanation, namely that time-varying risk explains the reversal effect. The study employs unbiased methods of return computation and uses data from 1975 to 1991 for nearly 1,000 UK companies. Overall, the evidence appears to be consistent with the overreaction hypothesis, subject to certain qualifications.     

Does the Conditional CAPM Work? Evidence from the Istanbul Stock Exchange

Using a sample of common stocks traded on the Istanbul Stock Exchange from February 1997 to April 2008, we test whether the conditional capital asset pricing model (CAPM) accurately prices assets. In our empirical analysis, we closely follow the methodology introduced in Lewellen and Nagel (2006). Our results show that the conditional CAPM fares no better than the static counterpart in pricing assets. Although market betas do vary significantly over time, the intertemporal variation is not large enough to drive average conditional alphas to zero.     

Una medida de eficiencia de mercado. Un enfoque de teoría de la información

In this paper, based on the concept of Shannon entropy, we propose a measure of market efficiency by using the empirical density function of returns. Under certain conditions of ergodicity and stationarity, it is shown that the sample entropy converges to the entropy of the dominant state. It is also shown that the proposed measure is consistent with some of the axioms from Artzner et al. (1999) of a coherent risk measure. Bounds on the behavior of entropy as a measure of efficiency on the basis of extreme cases are also established; going from deterministic processes to pure white noise stochastic processes. Finally, for illustrative purposes, we carry out several applications of the proposed efficiency measure of capital to different markets: DJIA, S&P500, FTSE100 and IPC.     

Spanning and efficiency in an economy with collective and individual risks

Much of the literature on incomplete markets emphasizes the study of conditions under which security market returns, either with or without derivative securities, span some exogenous set of cash flows. It is argued here that the only set of exogenous cash flows to which this literature is applicable are those that are contingent on existing assets' returns. The reason for this is that cash flows created by firms' production decisions are likely to be influenced by individual (unique) risk that is not incorporated into the market's existing information structure. The results of this article show that, if individual risk is pervasive, efficient allocation is likely to be achieved only in a large asset market which allows for the diversification of individual risk. The conditions for such diversification are derived and their implications discussed.     

Monotonicity in asset returns: New tests with applications to the term structure,the CAPM,and portfolio sorts

Many theories in finance imply monotonic patterns in expected returns and other financial variables. The liquidity preference hypothesis predicts higher expected returns for bonds with longer times to maturity; the Capital Asset Pricing Model (CAPM) implies higher expected returns for stocks with higher betas; and standard asset pricing models imply that the pricing kernel is declining in market returns. The full set of implications of monotonicity is generally not exploited in empirical work, however. This paper proposes new and simple ways to test for monotonicity in financial variables and compares the proposed tests with extant alternatives such as t-tests, Bonferroni bounds, and multivariate inequality tests through empirical applications and simulations.     

西方资产定价理论中的实体经济因素考察——以CAPM模型与B-S期权定价模型为例

本文根据马克思主义经济学有关实体经济因素决定虚拟资本价格的基本原理,分析和评价了CAPM与B-S模型;认为CAPM模型的建模思路存在重大错误;同时还发现,利息率是虚拟资本价格决定中与实体经济连接的重要桥梁,但在虚拟资本价格决定中,仅有利息率一个指标并不能充分反映实体经济的决定作用;本文还因B-S模型建模思路充分考虑了实体经济因素,而从马克思主义经济学角度给予客观评价。     

国际黄金市场发展状况及其趋势分析

在新的国际货币体系下，黄金的货币性虽然被取消，但由于黄金本身所拥有的保值性、安全性、流动性等属性，使其最根本的金融属性并没有降低。全世界40多个大小不一的黄金市场作为金融市场的构成部分，近10年来有了更快的发展。分析各主要黄金市场发展的现状，研究其发展趋势，对于研究其未来的发展路径以及对金融市场的作用具有相当重要的意义。     

The Halloween Effect and Japanese Equity Prices: Myth or Exploitable Anomaly

Bouman and Jacobsen (American Economic Review 92(5), 1618–1635, 2002) examine monthly stock returns for major world stock markets and conclude that returns are significantly lower during the May–October periods versus the November–April periods in 36 of 37 markets examined. They argue that, in general, the Halloween strategy outperforms the buy and hold strategy thereby casting doubt on the validity of the efficient market paradigm. More recently, Maberly and Pierce (Econ Journal Watch 1(1), 29–46, 2004) re-examine the evidence for U.S. equity prices and conclude that Bouman and Jacobsen’s results are not robust to alternative model specifications. Extending prior research, this paper examines the robustness of the Halloween strategy to alternative model specifications for Japanese equity prices. The Halloween effect is concentrated in the period prior to the introduction of Nikkei 225 index futures in September 1986. After the internationalization of Japanese financial markets in the mid-1980s, the Halloween effect disappears.JEL classification: G14, G15