Efficient Market Hypothesis and Behavioural Finance
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Published: Mon, 26 Feb 2018
1.1 Aim of Chapter
This chapter aims to give an overview of the dissertation. To start with, general backgrounds concerning the efficient market hypothesis (EMH), behavioral finance and market anomalies are mentioned briefly in order to provide better understanding about the modern area of financial study. Then, two opposed concepts of investment strategies, Contrarian Strategies and Momentum Strategies, are addressed leading to the next section which mention the main purpose and summary of findings of this research. Lastly, the structure of the dissertation has been outlined at the end of the chapter.
1.2 Background of knowledge about efficient market hypothesis (EMH)
The theory of market hypothesis (EMH) is one of the most crucial theories in standard finance that have been revised and tested over the past few decades to uncover its imperfection. This theory was introduced by Professor Eugene Fama in 1970. As defined in his article, the efficient market is the market where securities are priced, at any point of time, by accessible information. It is believed that the markets are extremely efficient that individual stocks and stock markets as a whole are fully reflected by all available information. When new information enters the market, stock prices incorporates the news and responds very quickly with our any delays; therefore security prices are the accurate source of data which can be used as signals in trading investment process. By examining the level of how relevant information reflects in security prices, Fama (1970) categorizes the market efficiency into three forms: weak, semi-strong and strong forms of EMH. However, this theory relies on certain assumptions, for example, there is no transaction cost paid in trading securities and it is costless for all participants to gather information available in the markets.
The weak form of EMH is the condition that exists when share prices are fully reflected by trading data such as past price (or return) histories. For that reason, investors cannot exploit mispriced securities and earn excess returns by using historical stock quotations or charts.
Semi-strong form of EMH is the condition that exists when share prices incorporates market trading data and publicly available information. The examples of this type of information are announcements of annual earnings, stock splits, annual reports, analyst forecasts, etc. As a consequence, investors cannot exhibit gains by rely only on fundamental and macro-economics data.
Strong form of EMH is the condition that exists when market prices of stocks adjusted according to every kind of accessible information. This includes hidden inside information which are known among specific group in the company (e.g. the top executives and group of operational managers) or some individuals that have monopolistic access to information (e.g. managements of mutual funds). Thus, abnormal profits cannot be generated by either using internal or external information of the company. In other words, both individual and professional investors cannot beat the market and earn excess returns in every way due to the perfect efficiency of the stock markets.
As claimed by efficient market hypothesis, market will be efficient in weak form if the past and future returns are not correlated, in other words, they are independently and identically distributed. Thus this refers to the idea of the random walk model. However, Fama (1970) affirms in his literature that the test of random walk model leads to the evidence of weak-form EMH, but not vice versa.
Burton (2003) identifies the definition of ‘random walk’ in his paper that it is the state where the flow of information on specific day is incorporated in stock prices on that day only, not for the subsequent period. The news announced in the market is unpredictable, thus stock prices changes are displayed in a random pattern. As a consequence, uninformed investors are able to earn equal rate of returns as what achieved by professional investors if they long position in well-diversified portfolios. In his paper, Burton tries to examine the criticism of the efficient market hypothesis and the idea that stock prices can be predicted based on initial valuation parameters (e.g. price-earnings multiple or dividend yield). He uses time-series analyses of accounting numbers and multiples and comes up with the results revealing that the stocks market are efficient enough, but it is difficult to predict the share prices. Moreover, the findings also reveal that anomalous behavior of stock prices may exist, but investors cannot create portfolio trading opportunity and gains excess risk adjusted returns.
Fama (1997) states in his study that there are many literatures concerning behavioral finance and market anomalies challenge the hypothesis of efficient market. The opposed idea suggests that stock prices slowly absorb information available, which can be denoted as the market inefficiency.
1.3 Behavioral Finance and Market Anomalies
Behavioral finance is the new area of financial study concentrating on the psychology of market and its participants. This field of study has started to appear in many academic journals from 1990s. Shefrin (2002) publish a book regarding the behavioral finance trying to find and explain reason behind the behavior of investors, both professional and individual. The author suggests that investors, who are sometimes prone to commend mistakes and errors, tend to rely on their emotional and psychological forces, thus this causes many market anomalies, the state where there is inefficiency in stock markets, to take place.
Two well-known papers of Berberis, Shleifer, and Vishny (1998) and Daniel, Hirshleifer, and Subramanyam (1997) proposed behavioral models to explain the conflicting theory of efficient market hypothesis. They reject the previous belief with the proposition that the behavioral biases (i.e. judgment bias) of investors cause the anomalies and knock down the old theory behind. They present the concepts of over-reaction and under-reaction which accommodates the existence of long-term excess returns.
Berberis, Shleifer, and Vishny (1996) create a model based on cognitive psychology of two judgment biases: the representativeness bias and conservatism. In their study, the empirical findings of investors’ behaviors are divided into two main groups: one perceives that earnings are mean-reverting. Thus, stock prices show a delayed short-term response and under-react to change in earnings. Another group believes that firms’ earnings are trending which leads to the overreaction in stock prices. The earnings follow the random walk process; hence, this leads to reversal of long-term returns.
Daniel, Hirshleifer, and Subramanyam (1997) have different views in conducting the behavioral models. They split the sample group of investors into two categories: informed and uninformed investors. They find that judgment biases are not found among the uninformed investors, but detected among the informed ones. Informed investors are the group of people that determine the stock prices. They are exposed to two kinds of behavioral biases: overconfidence and self-attribution biases. Overconfidence causes the overstatement in investors perception of their private stock prices signals, while self-attribution bias causes investors to underweight the public signals about the value of companies. Therefore, the circumstance of overreaction to private information and under-reaction to public information generates continuation of stock returns in the short run. Overreaction leads to the concept of contrarian investing, whereas underreaction induces the theory of momentum investing.
1.4 Investment Strategies
1.4.1 Contrarian Investing
Contrarian investing is the strategy that aims to generate profits by investing in the direction that goes against the conventional investors. In normal condition, short-sighted investors, who overweight the recent trends of past stocks prices and use this information to predict future prices, engage in buying stocks with good performance in the past hoping that it will continue to perform well in the near future. However, contrarian investing focuses on the opposite direction. People who employ this strategy tend to buy the shares that others have given up on due to either their poor past performance or their miserable and unclear future prospect. They expect the market to react to the behavior of the crowd, so that they can exploit the mispricing of securities and earn abnormal returns.
1.4.2 Momentum Investing
Momentum investing is the strategy that is the opposite of contrarian investing. People who employ this strategy seek for making profits by relying on the continuance of the past stock prices and trends in the market in an attempt to predict prospective prices in the future. It is believed that the good stocks with price increases and strong performance in the past will keep on outperforming and generate gains in the future, and vice versa for the poor stocks. Thus, momentum investing suggests investors to hold stocks that had high returns and sell those that had low returns (buy winners and sell losers).
The detailed of these two investment strategies will be discussed in the next chapter which both strategies will be supported by existing empirical evidences from several renowned academic papers.
1.5 Purpose and Findings of the Research
The purpose of this research is to examine the profitability of momentum strategies, which is one of the most debated investment strategies in financial study, in the UK stock market. This paper employs the prices and returns data of FTSE 100 composites – the top 100 biggest companies in London Stock Exchange – as a proxy of the whole UK stocks. The observation period lies between July 21, 2000 to July 21, 2010, which gives a total of 10 years period.
Thus, the main contribution of this study is to comprehensively revise existing literatures and employ the more up-to-date the data set with the well-known procedure to test the existence of momentum investing and its profitability in the UK market.
However, the findings reveal no evidence of momentum profitability in the observed time for UK stock market, which are inconsistent with the prior research conducted using the different sample periods.
1.6 Structure of the Dissertation
The rest of the dissertation is organized as follows: Chapter two comments on the review of the literature regarding the momentum strategies and its criticism, including the opposed theory of contrarian investing. Academic papers concerning the momentum strategies are divided into categories regarding the region of data employed. We carefully asserted and analyzed each paper to find the gaps which are necessary to be concerned for further researches in the future. Then, chapter three gives an overview of data and methodology used in this research. Chapter four shows the summary statistics of data, empirical results and interpretations. Finally, last chapter provides a summary of the results, as well as the limitations of the study.
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