Inefficient Markets: An Introduction to Behavioral Finance

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Summary: Arguments Against the Efficient Market Hypothesis
Review: Inefficient Markets by Harvard economist Andrei Schleifer provides a strong argument against the Efficient Market Hypothesis (EMH) in its various forms and an introduction to Behavioral Finance. Schleifer's main points are summarized below.

1. The EMH comes in three forms. The Weak Form states that an investor can not achieve returns above the market averages based on the analysis of historical stock price patterns (Technical Analysis). The Semi-Strong Form states that all publicly available news is reflected in stock prices almost instantaneously and that an investor can not beat the market averages by diligently tracking company earnings and other events (Fundamental Analysis). Finally, the Strong Form says that an investor can not beat the market even by using information that is not available to the public (Insider Trading). The Strong Form can be dismissed by considering the number of corporate executives currently under indictment or serving time for insider trading. Evidence against the Semi-Strong and Weak Forms can be found in the Small Stock Effect (small stocks outperform the market) and January Effect (the market does best in January) which seemed to hold until they were widely publicized but have presumably been negated since then by arbitrage. Additional evidence against the EMH can be found in the less than perfect correlation between the price movements of Royal Dutch and Shell Transport and Trading shares which jointly own the Royal Dutch Shell enterprise in a fixed 60%/40% ratio. Furthermore, the prevalence of a 10% to 20% discount in the share price of closed end funds relative to their net asset values suggests that the market is less than efficient.
2. In Chapters 2-4, Schleifer demonstrates the limits of arbitrage in maintaining efficient markets. He develops a mathematical model for predicting the returns of arbitrageurs (who accurately perceive the values of stocks) and noise traders (who incorrectly perceive the same values). His Noise Trader Model explains how noise traders can sometimes achieve higher returns than arbitrageurs based on the "hold more" and "create space" effects. The "hold more" effect is based on the community of noise traders egging each other on as was seen in the technology bubble that burst in 2000. The "create space" effect says that the wider the range of incorrect perceptions held by noise traders, the less effective arbitrageurs will be in bring stock prices back to their correct values. Schleifer uses the Noise Trader Model to make additional predictions about the market behavior of closed end funds and shows that, unlike the EMH, it accurately models such phenomena as the rise in share price to the underlying net asset value upon liquidation or reorganization as an open end fund. Finally, he shows that professional arbitrageurs, such as hedge fund operators, are forced to adopt more conservative tactics than individual arbitrageurs by their need to retain clients and funding.
3. In Chapters 5 and 6, Schleifer develops a model of Investor Sentiment based on investors' patterns of psychological underreaction and overreaction. Investors tend to underreact to new information (such as reported earnings) by modifying their perception of a stock's value by less that the new information would suggest and continuing to extrapolate the old stock price trend. If confronted with repeated inputs of new information that consistently points in the same direction, investors tend to overreact by discarding the old model, accepting the recent trend as the new model, and extrapolating it into the future. Finally, he shows how investor sentiments can form a positive feedback trading environment in which arbitrage can actually destabilize the market.

This is a book for serious students of finance. It's not a "Behavioral Finance for Dummies". However, the math does not require more than a year of calculus and a good understanding of calculus-based probability and statistics. Schleifer's writing style is remarkably clear for an academic economist (many of whom I find able to obfuscate the simplest concepts). Overall, Inefficient Markets is a long-overdue reexamination of the theoretical underpinnings of modern finance theory.


Rating:
Summary: A good intro to Behavioral Finance
Review: Markets are not efficient in part because Investor Sentiment is a strong factor creating momentum (either upward or downward trend, whether sentiment is positive or negative). Also, arbitrage is very weak, as there are no proper securities substitutes, shorting the indexes is too risky. The "Noise Trader Risk" is too great. Meaning equity values may continue to diverge long enough for the arbitrageurs to loose their shirt betting on convergence. The investor type is a very important characteristic to factor. This explains the close end fund puzzle. The discount on closed end fund tracks the fate of small cap stocks. When small cap stocks do poorly, the discount on closed end funds deepens. This is because both investments are dominated by the same type of investors: individuals - small investors. Thus, both investment types are subject to small investors' sentiments.

Rating:
Summary: A good intro to Behavioral Finance
Review: Markets are not efficient in part because Investor Sentiment is a strong factor creating momentum (either upward or downward trend, whether sentiment is positive or negative). Also, arbitrage is very weak, as there are no proper securities substitutes, shorting the indexes is too risky. The "Noise Trader Risk" is too great. Meaning equity values may continue to diverge long enough for the arbitrageurs to loose their shirt betting on convergence. The investor type is a very important characteristic to factor. This explains the close end fund puzzle. The discount on closed end fund tracks the fate of small cap stocks. When small cap stocks do poorly, the discount on closed end funds deepens. This is because both investments are dominated by the same type of investors: individuals - small investors. Thus, both investment types are subject to small investors' sentiments.

Rating:
Summary: Necessary Book for Finance
Review: The material in this book is necessary for anyone who is responsible for managing money or involved with a business entity doing trading in financial markets. Increasingly this is "everyone."

The good news is that the conclusions and punchlines are presented clearly and simply. A person who does not want to follow the math (there is a lot of it) can skip to the arguments and conclusions and get an enormous amount of valuable information. The bad news is that little effort has been expended to make the math attractive. A person wishing to slog through the math will have to be prepared to sit down with pencil & paper & patience. Some editing by someone who cared would have made this book much more attractive to the average student. Martin Baxter & Andrew Rennie's "Financial Calculus" gives a good example of how this can be done.

Rating:
Summary: Too much maths but interesting interpretation
Review: There is too much maths in the book. However, the comments and interpretation on various models are very interesting. The authour distinguish between arbitrageurs and noise traders. He also give us a theory of substituability which is interesting but inapplicable in reality. Too much theory also with a lot of hypothesis that are not respected in real markets.
I was looking more for a book on investment psychology and I was disappointed.