Download Behavioral Finance: Understanding the Influence of Psychology on Financial Markets and more Study notes Investment Management and Portfolio Theory in PDF only on Docsity! y g ( ) Lesson # 24 MARKET EFFICIENCY Contd… Behavioral Finance: Behavioral finance is the study of the influence of psychology on the behavior of financial practitioners and the subsequent effect on markets. Sewell says "I think of behavioral finance as simply "open-minded finance". Thaler says 'This area of enquiry is sometimes referred to as "behavioral finance," but we call it "behavioral economics." Behavioral economics combines the twin disciplines of psychology and economics to explain why and how people make seemingly irrational or illogical decisions when they spend, invest, save, and borrow money.” This paper examines the case for major changes in the behavioral assumptions underlying economic models, based on apparent anomalies in financial economics. Arguments for such changes based on claims of "excess volatility" in stock prices appear flawed for two main reasons: there are serious questions whether the phenomenon exists in the first place and, even if it did exist, whether radical change in behavioral assumptions is the best avenue for current research. The paper also examines other apparent anomalies and suggests conditions under which such behavioral changes are more or less likely to be adopted. Because psychology systematically explores human judgment, behavior, and well-being, it can teach us important facts about how humans differ from traditional economic assumptions. In this essay I discuss a selection of psychological findings relevant to economics. Standard economics assumes that each person has stable, well-defined preferences, and that she rationally maximizes those preferences. Section 2 considers what psychological research teaches us about the true form of preferences, allowing us to make economics more realistic within the rational choice framework. Section 3 reviews research on biases in judgment under uncertainty; because those biases lead people to make systematic errors in their attempts to maximize their preferences, this research poses a more radical challenge to the economics model. The array of psychological findings reviewed in Section 4 points to an even more radical critique of the economics model: Even if we are willing to modify our familiar assumptions about preferences, or allow that people make systematic errors in their attempts to maximize those preferences, it is sometimes misleading to conceptualize people as attempting to maximize well-defined, coherent, or stable preferences. Market efficiency survives the challenge from the literature on long-term return anomalies. Consistent with the market efficiency hypothesis that the anomalies are chance results, apparent overreaction to information is about as common as under reaction and post-event continuation of pre-event abnormal returns is about as frequent as post-event reversal. Most important, consistent with the market efficiency prediction that apparent anomalies can be due to methodology, most long-term return anomalies tend to disappear with reasonable changes in technique. The field of modern financial economics assumes that people behave with extreme rationality, but they do not. Furthermore, people’s deviations from rationality are often systematic. Behavioral finance relaxes the traditional assumptions of financial economics by incorporating these observable, systematic, and very human departures from rationality into standard models of financial markets. We highlight two common mistakes investors make: excessive trading and the tendency to disproportionately hold on to losing investments while selling winners. We argue that these systematic biases have their origins in human psychology. The tendency for human beings to be overconfident causes the first bias in investors, and the human desire to avoid regret prompts the second. docsity.com
