Best Selling Books by Richard H. Thaler

We argue that narrow framing, whereby an agent who is offered a new gamble evaluates that gamble in isolation, separately from other risks she already faces, may be a more important feature of decision-making under risk than previously realized. To demonstrate this, we present evidence on typical attitudes to independent monetary gambles with both large and small stakes and show that across a wide range of utility functions, including all expected utility and many non-expected utility specifications, the only ones that can easily capture these attitudes are precisely those exhibiting narrow framing. Our analysis also makes predictions about the kinds of preferences that might be able to address the stock market participation and equity premium puzzles. We illustrate these predictions in simple portfolio choice and equilibrium settings

The equity premium puzzle, first documented by Mehra and Prescott, refers to the empirical fact that stocks have greatly outperformed bonds over the last century. As Mehra and Prescott point out, it appears difficult to explain the magnitude of the equity premium within the usual economics paradigm because the level of risk aversion necessary to justify such a large premium is implausibly large. We offer a new explanation based on Kahneman and Tversky''s ''prospect theory''. The explanation has two components. First, investors are assumed to be ''loss averse'' meaning they are distinctly more sensitive to losses than to gains. Second, investors are assumed to evaluate their portfolios frequently, even if they have long-term investment goals such as saving for retirement or managing a pension plan. We dub this combination ''myopic loss aversion''. Using simulations we find that the size of the equity premium is consistent with the previously estimated parameters of prospect theory if investors evaluate their portfolios annually. That is, investors appear to choose portfolios as if they were operating with a time horizon of about one year. The same approach is then used to study the size effect. Preliminary results suggest that myopic loss aversion may also have some explanatory power for this anomaly.

Some eleven million 401(k) plan participants take a concentrated equity position in their retirement savings account, investing more than 20% of the balance in their employer''s common stock. Yet investing in the stock of one''s employer is a risky investment on two counts: single securities are riskier than diversified portfolios (such as mutual funds), and the employee''s human capital is typically positively correlated with the performance of the company. In the worst-case scenario, illustrated by the Enron bankruptcy, workers can lose their jobs and much of their retirement wealth simultaneously. For workers who expect to work for the company for many years, a dollar of company stock can be valued at less than 50 cents to the worker after accounting for the risks. But employees still invest voluntarily in their employers'' stock, and many employers insist on making matching contributions in stock, despite the fact that a dollar of investment or contribution may be worth only 50 cents on the dollar. How can competitive labor markets sustain a situation in which employers and employees make such a fundamental miscalculation? We provide evidence that employees underestimate the risk of owning company stock, while employers overestimate the benefits associated with employee stock ownership relative to its costs. This evidence provides strong reasons to consider legal reforms in this domain. We make suggestions that would increase employees'' freedom of choice and improve their welfare, but without imposing significant costs on well-meaning but ill-informed employers.

A question of increasing interest to researchers in a variety of fields is whether the incentives and experience present in many "real world" settings mitigate judgment and decision-making biases. To investigate this question, we analyze the decision making of National Football League teams during their annual player draft. This is a domain in which incentives are exceedingly high and the opportunities for learning rich. It is also a domain in which multiple psychological factors suggest teams may overvalue the "right to choose" in the draft -- non-regressive predictions, overconfidence, the winner''s curse and false consensus all suggest a bias in this direction. Using archival data on draft-day trades, player performance and compensation, we compare the market value of draft picks with the historical value of drafted players. We find that top draft picks are overvalued in a manner that is inconsistent with rational expectations and efficient markets and consistent with psychological research.