In traditional models, arbitrage in a given security is performed by a large number of diversified investors taking small positions against its mispricing. In reality, however, arbitrage is conducted by a relatively small number of highly specialized investors who take large positions using other people's money. Such professional arbitrage has a number of interesting implications for security pricing, including the possibility that arbitrage becomes ineffective in extreme circumstances, when prices diverge far from fundamental values. The model also suggests where anomalies in financial markets are likely to appear, and why arbitrage fails to eliminate them.

https://papers.ssrn.com/sol3/Delivery.cfm/nber_w5167.pdf?abstractid=225230&mirid=1&type=2

The Limits of Arbitrage

Theoretical models of financial markets built on the assumption that some investors are overconfident yield one central prediction: overconfident investors will trade too much. We test this prediction by partitioning investors on the basis of a variable that provides a natural proxy for overconfidence--gender. Psychological research has established that men are more prone to overconfidence than women. Thus, models of investor overconfidence predict that men will trade more and perform worse than women. Using account data for over 35,000 households from a large discount brokerage firm, we analyze the common stock investments of men and women from February 1991 through January 1997. Consistent with the predictions of the overconfidence models, we document that men trade 45 percent more than women and earn annual risk-adjusted net returns that are 1.4 percent less than those earned by women. These differences are more pronounced between single men and single women; single men trade 67 percent more than single women and earn annual risk-adjusted net returns that are 2.3 percent less than those earned by single women.

https://papers.ssrn.com/sol3/Delivery.cfm/98110615.pdf?abstractid=139415&rulid=175370&mirid=3

Boys Will Be Boys: Gender, Overconfidence, and Common Stock Investment

Textbook arbitrage in financial markets requires no capital and entails no risk. In reality, almost all arbitrage requires capital, and is typically risky. Moreover, professional arbitrage is conducted by a relatively small number of highly specialized investors using other people's capital. Such professional arbitrage has a number of interesting implications for security pricing, including the possibility that arbitrage becomes ineffective in extreme circumstances, when prices diverge far from fundamental values. The model also suggests where anomalies in financial markets are likely to appear, and why arbitrage fails to eliminate them. ONE OF THE FUNDAMENTAL concepts in finance is arbitrage, defined as "the simultaneous purchase and sale of the same, or essentially similar, security in two different markets for advantageously different prices" (Sharpe and Alexander (1990)). Theoretically speaking, such arbitrage requires no capital and entails no risk. When an arbitrageur buys a cheaper security and sells a more expensive one, his net future cash flows are zero for sure, and he gets his profits up front. Arbitrage plays a critical role in the analysis of securities markets, because its effect is to bring prices to fundamental values and to keep markets efficient. For this reason, it is extremely important to understand how well this textbook description of arbitrage approximates reality. This article argues that the textbook description does not describe realistic arbitrage trades, and, moreover, the discrepancies become particularly important when arbitrageurs manage other people's money. Even the simplest realistic arbitrages are more complex than the textbook definition suggests. Consider the simple case of two Bund futures contracts to deliver DM250,000 in face value of German bonds at time T, one traded in London on LIFFE and the other in Frankfurt on DTB. Suppose for the moment, counter factually, that these contracts are exactly the same. Suppose finally that at some point in time t the first contract sells for DM240,000 and the second for DM245,000. An arbitrageur in this situation would sell a futures contract in Frankfurt and buy one in London, recognizing that at time T he is perfectly hedged. To do so, at time t, he would have to put up some good faith money, namely DM3,000 in London and DM3,500 in Frankfurt, leading to a

https://pages.stern.nyu.edu/~cedmond/phd/Shleifer%20Vishny%20JF%201997.pdf

Theoretical models predict that overconedent investors trade excessively We test this prediction by partitioning investors on gender Psychological research demonstrates that, in areas such as enance, men are more overconedent than women Thus, theory predicts that men will trade more excessively than women Using account data for over 35,000 households from a large discount brokerage, we analyze the common stock investments of men and women from February 1991 through January 1997 We document that men trade 45 percent more than women Trading reduces men’s net returns by 265 percentage points a year as opposed to 172 percentage points for women It’s not what a man don’t know that makes him a fool, but what he does know that ain’t so Josh Billings, nineteenth century American humorist It is difecult to reconcile the volume of trading observed in equity markets with the trading needs of rational investors Rational investors make periodic contributions and withdrawals from their investment portfolios, rebalance their portfolios, and trade to minimize their taxes Those possessed of superior information may trade speculatively, although rational speculative traders will generally not choose to trade with each other It is unlikely that rational trading needs account for a turnover rate of

/pdf/boys-will-be-boys-gender-overconfidence-and-common-stock-2ctwfizezu.pdf

Boys will be Boys: Gender, Overconfidence, and Common Stock Investment

UNTVERSITY OF CALIFORNIA AT BERKELEY Department of Economics Berkeley, CaHfornia 94720-3880 Working Paper No. 97-251 Psychology and Economics Matthew Rabin Department of Economics University of California, Berkeley January 1997 Key words: bounded rationality, decision making, fairness, framing effects, heuristics and biases, preferences, psychology, reciprocity, reference-dependent utility JEL Classification: A12, B49, D i l , D60, D81, D83, D91 This is a longer version of an essay under preparation for possible publication in the Journal of Economic Literature. I thank John Pencavel and anonymous referees for earlier comments on its structure and content. For comments on this draft, I thank Steven Blatt, Colin Camerer, Peter Diamond, Erik Eyster, Ernst Fehr, Danny Kahneman, George Loewenstein, Ted O'Donoghue, and John Pencavel. For helpful conversations over the past several years on topics covered in this essay, I thank George Akerlof, Gary Chamess, Eddie Dekel, Peter Diamond, David Laibson, David I. Levine, George Loewenstein, Rob MacCoun, James Montgomery, Vai-Lam Mui, Drazen Prelec, and especially Colin Camerer, Danny Kahneman, and Richard Thaler. Co-authors on research related to the topics of this essay include David Bowman, Deborah Minehart, Ted O'Donoghue, and Joel Schrag. Helpful research assistance was provided by Gadi Barlevy, Nikki Blasberg, Gail Brennan, Paul Ellickson, April Franco, Marcus Heng, Bruce Hsu, Jin Woo Jung, and especially Steven Blatt, Jimmy Chan, Erik Eyster, and Clara Wang. I am extremely grateful for financial support from the Russell Sage and Alfred P. Sloan Foundations.

https://www.jstor.org/stable/pdfplus/2564950.pdf

Psychology and Economics

Uncertainty Aversion, Risk Aversion, and the Optimal Choice of Portfolio

In a capitalist economy, prices serve to equilibrate supply and demand for goods and services, continually changing to reallocate resources to their most efficient uses. However, secondary stock market prices, often viewed as the most "informationally efficient" prices in the economy, have no direct role in the allocation of equity capital since managers have discretion in determining the level of investment. What is the link between stock price informational efficiency and economic efficiency? We present a model of the stock market in which: (i) managers have discretion in making investments and must be given the right incentives; and (ii) stock market traders may have important information that managers do not have about the value of prospective investment opportunities. In equilibrium, information in stock prices will guide investment decisions because managers will be compensated based on informative stock prices in the future. The stock market indirectly guides investment by transferring two kinds of information: information about investment opportunities and information about managers' past decisions. However, because this role is only indirect, the link between price efficiency and economic efficiency is tenuous. We show that stock price efficiency is not sufficient for economic efficiency by showing that the model may have another equilibrium in which prices are strong-form efficient, but investment decisions are suboptimal. We also suggest that stock market efficiency is not necessary for investment efficiency by considering a banking system that can serve as an alternative institution for the efficient allocation of investment resources. IN A CAPITALIST SOCIETY, prices for goods and service play the central role in resource allocation. The strength of capitalism lies in its ability to make these prices reflect essential information so that resources are deployed efficiently. Consider a fishmonger whose prices for different kinds of fish change every day in response to availability. These prices have a direct effect on the behavior of customers entering the shop: if the price is high they may choose to eat beef for dinner instead. In other words, the allocation of fish to the most efficient uses (in this case, to the people with the highest marginal utility of fish consumption) is accomplished by price changes. These price changes directly regulate the use of the fish. Now consider the equity capital market and its relation to the allocation of funds for capital investment. If a company's share price goes

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Stock Market Efficiency and Economic Efficiency: Is There a Connection?

We consider a model of the stock market with delegated portfolio management. All agents are rational: some trade for hedging reasons, some investors optimally contract with portfolio managers who may have stock-picking abilities, and portfolio managers trade optimally given the incentives provided by this contract. Managers try, but sometimes fail, to discover profitable trading opportunities. Although it is best not to trade in this case, their clients cannot distinguish 'actively doing nothing,' in this sense, from 'simply doing nothing.' Because of this problem: (i) some portfolio managers trade even though they have no reason to prefer one asset to another (noise trade). We also show that, (ii), the amount of such noise trade can be large compared to the amount of hedging volume. Perhaps surprisingly, (iii), noise trade may be Pareto-improving. Noise trade may be viewed as a public good. Results (i) and (ii) are compatible with observed high levels of turnover in securities markets. Result (iii) illustrates some of the possible subtleties of the welfare economics of financial markets.

Noise Trading, Delegated Portfolio Management, and Economic Welfare

Nash Equilibrium under Knightian Uncertainty: Breaking Down Backward Induction

This paper develops a simple model of sovereign debt in which defaulting nations are excluded from capital markets and regain access by making partial repayments. This implication of the model is consistent with the historical evidence that defaulting countries return to international loan markets soon after a settlement but after varying periods of exclusion. Copyright 1995 by Economics Department of the University of Pennsylvania and the Osaka University Institute of Social and Economic Research Association.

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James Dow

Papers

Uncertainty Aversion, Risk Aversion, and the Optimal Choice of Portfolio

Stock Market Efficiency and Economic Efficiency: Is There a Connection?

Noise Trading, Delegated Portfolio Management, and Economic Welfare

Nash Equilibrium under Knightian Uncertainty: Breaking Down Backward Induction

Default, Settlement, and Signalling--Lending Resumption in a Reputational Model of Sovereign Debt