There is a worldwide trend toward defined contribution saving plans and growing interest in privatized Social Security plans. In both environments, individuals are given some responsibility to make their own asset-allocation decisions, raising concerns about how well they do at this task. This paper investigates one aspect of the task, namely diversification. We show that some investors follow the “1/n strategy”: they divide their contributions evenly across the funds offered in the plan. Consistent with this naive notion of diversification, we find that the proportion invested in stocks depends strongly on the proportion of stock funds in the plan.

There is a worldwide trend towards defined contribution savings plans, where investors are often able to select their own portfolios. How much is this freedom of choice worth? We present retirement investors with information about the distribution of outcomes they could expect to obtain from the portfolios they picked for themselves, and the same information for the median portfolio selected by their peers. A majority of our survey participants actually prefer the median portfolio to the one they picked for themselves. We investigate various explanations for these findings and offer some evidence that the results are partly attributable to the fact that investors do not have well‐defined preferences.

Preface xi Richard H. Thaler Acknowledgments xix List of Abbreviations xxiii Chapter 1: A Survey of Behavioral Finance by Nicholas Barberis and Richard H. Thaler 1 Part I: Limits to Arbitrage Chapter 2: The Limits of Arbitrage by Andrei Shleifer and Robert W. Vishny 79 Chapter 3: How Are Stock Prices Affected by the Location of Trade? by Kenneth A. Froot and Emil M. Dabora 102 Chapter 4: Can the Market Add and Subtract? Mispricing in Tech Stock Carve-outs by Owen A. Lamont and Richard H. Thaler 130 Part II: I Stock Returns and the Equity Premium Chapter 5: Valuation Ratios and the Long-run Stock Market Outlook: An Update by John Y. Campbell and Robert J. Shiller 173 Chapter 6: Myopic Loss Aversion and the Equity Premium Puzzle by Shlomo Benartzi and Richard H. Thaler 202 Chapter 7: Prospect Theory and Asset Prices by Nicholas Barberis, Ming Huang, and Tano Santos 224 Part III: Empirical Studies of Overreaction and Underreaction Chapter 8: Contrarian Investment, Extrapolation, and Risk by Josef Lakonishok, Andrei Shleifer, and Robert W. Vishny 273 Chapter 9: Evidence on the Characteristics of Cross-sectional Variation in Stock Returns by Kent Daniel and Sheridan Titman 317 Chapter 10: Momentum by Narasimhan Jegadeesh and Sheridan Titman 353 Chapter 11: Market Efficiency and Biases in Brokerage Recommendations by Roni Michaely and Kent L. Womack 389 Part IV: Theories of Overreaction and Underreaction Chapter 12: A Model of Investor Sentiment by Nicholas Barberis, Andrei Shleifer, and Robert W. Vishny 423 Chapter 13: Investor Psychology and Security Market Under- and Overreaction by Kent Daniel, David Hirshleifer, and Avanidhar Subrahmanyam 460 Chapter 14: A Unified Theory of Underreaction, Momentum Trading, and Overreaction in Asset Markets by Harrison Hong and Jeremy C. Stein 502 Part V: Investor Behavior Chapter 15: Individual Investors by Brad M. Barber and Terrance Odean 543 Chapter 16: Naive Diversification Strategies in Defined Contribution Savings Plans by Shlomo Benartzi and Richard H. Thaler 570 Part VI: Corporate Finance Chapter 17: Rational Capital Budgeting in an Irrational World by Jeremy C. Stein 605 Chapter 18: Earnings Management to Exceed Thresholds by Francois Degeorge, Jayendu Patel, and Richard Zeckhauser 633 Chapter 19: Managerial Optimism and Corporate Finance by J. B. Heaton 667 List of Contributors 685 Index 695

This paper examines the proposition that fluctuations in discounts of closed-end funds are driven by changes in individual investor sentiment. The theory implies that discounts on various funds move together, that new funds get started when seasoned funds sell at a premium or a small discount, and that discounts are correlated with prices of other securities affected by the same investor sentiment. The evidence supports these predictions. In particular, the authors find that both closed-end funds and small stocks tend to be held by individual investors, and that the discounts on closed-end funds narrow when small stocks do well.

As firms switch from defined-benefit plans to defined-contribution plans, employees bear more responsibility for making decisions about how much to save. The employees who fail to join the plan or who participate at a very low level appear to be saving at less than the predicted life cycle savings rates. Behavioral explanations for this be-havior stress bounded rationality and self-control and suggest that at least some of the low-saving households are making a mistake and would welcome aid in making decisions about their saving. In this paper, we propose such a prescriptive savings program, called Save More Tomorrow (hereafter, the SMarT program). The essence of the program is straightforward: people commit in advance to allocat-ing a portion of their future salary increases toward retirement savings. We report evidence on the first three implementations of the SMarT program. Our key findings, from the first implementation, which has We are grateful to Brian Tarbox for implementing the Save More Tomorrow plan and for sharing the data with us. We would also like to thank many people at the following

Recent equity carve-outs in U.S. technology stocks appear to violate a basic premise of financial theory: identical assets have identical prices. In our 19982000 sample, holders of a share of company A are expected to receive x shares of company B, but the price of A is less than x times the price of B. A prominent example involves 3Com and Palm. Arbitrage does not eliminate this blatant mispricing due to short-sale constraints, so that B is overpriced but expensive or impossible to sell short. Evidence from options prices shows that shorting costs are extremely high, eliminating exploitable arbitrage opportunities.

We argue that “narrow framing,” whereby an agent who is offered a new gamble evaluates that gamble in isolation, may be a more important feature of decision-making than previously realized. Our starting point is the evidence that people are often averse to a small, independent gamble, even when the gamble is actuarially favorable. We find that a surprisingly wide range of utility functions, including many nonexpected utility specifications, have trouble explaining this evidence, but that this difficulty can be overcome by allowing for narrow framing. Our analysis makes predictions as to what kinds of preferences can most easily address the stock market participation puzzle.

Research in experimental psychology suggests that, in violation of Bayes' rule, most people tend to “overreact” to unexpected and dramatic news events. This study of market efficiency investigates whether such behavior affects stock prices. The empirical evidence, based on CRSP monthly return data, is consistent with the overreaction hypothesis. Substantial weak form market inefficiencies are discovered. The results also shed new light on the January returns earned by prior “winners” and “losers.” Portfolios of losers experience exceptionally large January returns as late as five years after portfolio formation.