Hersh Shefrin

Behavioral Portfolio Theory

We develop a positive behavioral portfolio theory (BPT) and explore its implications for portfolio constrution and security design. The optimal portfolios of BPT investors resemble combinations of bonds and lotterly tickets consistent with Friedman and Savages (1948) observation. We compare the BPT efficient frontier with the mean-variance efficient frontier and show that, in general, the two frontiers do not coincide. Optimal BPT portfolios are also different from optimal CAPM portfolios. In particular, the CAPM two-fund separation does not hold in BPT. We present BPT in a single mental account version (BPT-SA) and a multiple mental account version (BPT-SA). BPT-SA investors integrate their portfolios into a single mental account, while BPT-SA investors segregate their portfolios into several mental accounts. BPT-SA portfolios resemble layered pyramids, where layers are associated with aspirations. We explore a two-layer portfolio where the low aspiration layer is designed to avoid poverth while the high aspiration layer is designed for a shot at riches.

Explaining investor preference for cash dividends

Abstract The well-known tendency of investors to favor cash dividends emerges quite naturally in two new theories of choice behavior [the theory of self-control due to Thaler and Shefrin (1981), and the version of prospect theory set out by Kahneman and Tversky (1979)]. Although our treatment is novel when viewed from the perspective of standard financial theory, it provides explanations for a phenomenon that has long been described as perplexing.

Behavioral Capital Asset Pricing Theory

This paper develops a capital asset pricing theory in a market where noise traders interact with information traders. Noise traders are traders who commit cognitive errors while information traders are free of cognitive errors. The theory includes the determination of the mean-variance efficient frontier, the return on the market portfolio, the term structure, and option prices. The paper derives a necessary and sufficient condition for the existence of price efficiency in the presence of noise traders and analyzes the effects of noise traders on price efficiency, volatility, return anomalies, volume, and noise trader survival.

Optimal Investment in Schooling When Incomes Are Risky

This study demonstrates a tractable method for analyzing schooling investment with risky incomes. Constant relative risk aversion is assumed, and borrowing in a rudimentary capital market is allowed. A linear, variance-components model on log (real income) is estimated. Only unexplained variation is treated as a source of risk. Illustrative empirical results indicate that students should take either 4 years of college or none at all, depending on time preference, loan availability, and degree of risk aversion. Estimate risk-adjusted rates of return to college exceed 10 percent for some parameter values. Risk adjustments for college rates are small but positive.

Information and securities: A note on pareto dominance and the second best

A unified analysis is provided of two related problems: the first concerns the welfare impact of changing the set of tradeable securities in an incomplete market economy. The second concerns the welfare implications of changing the common information structure faced by all agents. Both problems arise from a common second-best framework in which expanding the set of trading opportunities can lead to a Pareto worsening. Journal of Economic Literature Classification Number: 026. ,rl 1987 Academic Press. Inc. In this note we provide a unified analysis of two related problems: The first concerns the welfare impact of changing the set of tradeable securities in an incomplete market economy. The second concerns the welfare implifications of changing the common information structure faced by all agents. We will discuss apparent paradoxial results that arise in both problems, using a single geometric example. The example provides a clear illustration of the source of the apparent paradoxes; both problems arise from a common second-best framework. (By second-best we mean the Lipsey-Lancaster [20] idea of additional constraints on allocations, over and above resource availability constraints.) Our discussion brings together two related but distinct literatures. The * We are greatly indebted to James Ohlson for many constructive comments; and to David Kreps and N. V. Long for comments on a previous draft.

Behavioral decision making, forecasting, game theory, and role-play

Abstract Green’s finding that the outcome of role-play provides forecasts that are superior to those of game theorists highlights some of the unrealistic assumptions used in traditional game theory. In this commentary I discuss how elements studied in the behavioral decision literature impact the manner in which people behave in conflict situations studied by Green, and in the spectrum auction conducted in the United States. The main behavioral elements discussed are loss aversion, myopia, and the winner’s curse.

Behavioral Portfolio Analysis of Individual Investors

Existing studies on individual investors’ decision-making often rely on observable socio-demographic variables to proxy for underlying psychological processes that drive investment choices. Doing so implicitly ignores the latent heterogeneity amongst investors in terms of their preferences and beliefs that form the underlying drivers of their behavior. To gain a better understanding of the relations among individual investors’ decision-making, the processes leading to these decisions, and investment performance, this paper analyzes how systematic differences in investors’ investment objectives and strategies impact the portfolios they select and the returns they earn. Based on recent findings from behavioral finance we develop hypotheses which are tested using a combination of transaction and survey data involving a large sample of online brokerage clients. In line with our expectations, we find that investors driven by objectives related to speculation have higher aspirations and turnover, take more risk, judge themselves to be more advanced, and underperform relative to investors driven by the need to build a financial buffer or save for retirement. Somewhat to our surprise, we find that investors who rely on fundamental analysis have higher aspirations and turnover, take more risks, are more overconfident, and outperform investors who rely on technical analysis. Our findings provide support for the behavioral approach to portfolio theory and shed new light on the traditional approach to portfolio theory.

Credit card behavior, financial styles, and heuristics

The paper makes four contributions. First, the paper provides new data and findings about credit card usage segmentation in respect to spending and borrowing behavior. Second, it sets the new findings against the backdrop of the newly emerging literature on financial literacy. A great variability occurs in financial literacy across American consumers. Third, the paper describes fast and frugal heuristics aimed to help consumers make effective, and in some cases better, budgeting decisions when they use credit cards. Fourth, the paper describes the introduction of a new set of online financial tools, offered by a large credit card company, which consumers are now using to make decisions about their spending and borrowing, and links these tools to the heuristics under discussion. Fast and frugal heuristics are likely to be especially valuable to consumers with low confidence in their online skills. Notably, 25% of credit cardholders report that they have low confidence using online technology to manage their finances, with the corresponding figure being 44% for those most at risk.

A Tale of Two Investors: Estimating Optimism and Overconfidence

We estimate investors’ sentiment from option and stock prices by anchoring objective beliefs to a neoclassical pricing kernel. Our estimates of sentiment correlate well with other sentiment measures such as the Baker–Wurgler index, the Yale/Shiller crash confidence index and the Duke/CFO survey responses, and yet contain additional information. Our analysis points out three significant issues related to overconfidence. First, the Baker–Wurgler index strongly reflects excessive optimism but not overconfidence. Second, overconfidence drives the pricing kernel puzzle. Third, the dynamics of optimism and overconfidence generate a perceived negative risk-return relationship, while objectively the relationship is positive. Optimism and overconfidence about market returns co-move together, inflating asset prices in good times and exacerbating market crashes in bad times.

Exact Aggregation and the Finite Basis Property

The authors address the following two fundamental questions in the theory of exact aggregation: (1) What restrictions, if any, need to be imposed on the vector of aggregates in order that the aggregate demand functional representation be nontrivial and economically interesting? (2) What economic restrictions, if any, does exact aggregation impose on demand functions, both at the ind ividual and aggregate levels? The answer to the first question involv es the information censored or masked by the aggregates. The answer t o the second question involves a condition known as the finite basis property, and its implications for Engel curve similarity across pric es, commodities, and consumers. Copyright 1988 by Economics Department of the University of Pennsylvania and the Osaka University Institute of Social and Economic Research Association.