Overconfidence and Bubbles in Experimental Asset Markets

This paper investigates the relationship between market overconfidence and occurrence of stock-price bubbles. Sixty participants traded stocks in 10 experimental asset markets. Markets were constructed on the basis of subjects' overconfidence: The most overconfident subjects form high overconfidence markets and the least overconfident subjects low overconfidence markets. Prices in low overconfidence markets tend to track the fundamental asset value more accurately than prices in high overconfidence markets and are significantly lower and less volatile. Additionally, we observe significantly higher bubble measures and trading volume in high overconfidence markets. Two possible explanations for these differences are analyzed: While price expectations are significantly higher in high overconfidence markets, no differences in the average degree of risk aversion were detected.     

Determinants of stock price bubbles

In this paper we propose a cross-sectional model of the determinants of asset price bubbles. Using 589 firms listed on the NYSE, we find conclusive evidence that trading volume and share price volatility have statistically significant effects on asset price bubbles. However, evidence from sector-based stocks is mixed. We find that for firms belonging to electricity, energy, financial, and banking sectors, and for the smallest size firms, trading volume has a statistically significant and positive effect on bubbles. We do not discover any robust evidence of a statistically significant effect of share price volatility on bubbles at the sector-level.     

Direct sale of information when precision is unobservable

Abstract.  This paper studies the incentives of an information seller to provide precise information when precision is not observable and investors with rational expectations can extract information from the equilibrium asset price. I show that the seller can verify her precision by employing a non‐linear contract. I derive the equilibrium fee for information as a function of the seller's incentives, the sales volume, and buyers' trading intensity. I also analyse the implications of allowing the seller to trade on her own account for truthfulness and precision choice. JEL Classification: G11, G14, D42     

自我归因偏差、学习与股民的过度自信

本文利用中国股民交易记录数据考察了自我归因偏差带来的反馈效应和投资经验带来的学习效应对股民的过度自信的影响。研究发现，股民的历史投资收益对其过度交易存在正向影响，即股民历史投资收益越高，则过度交易程度就越大。这表明良好的历史投资收益会通过自我归因偏差心理加剧投资者过度自信程度。而在控制了历史投资表现之后，笔者发现股民的投资经验对其过度交易的影响并不显著。过度交易或者过度自信并没有随着股民投资经验的积累而得到减弱。     

Overconfidence and Market Efficiency with Heterogeneous Agents

We study financial markets in which both rational and overconfident agents coexist and make endogenous information acquisition decisions. We demonstrate the following irrelevance result when a positive fraction of rational agents (endogenously) decides to become informed in equilibrium, prices are set as if all investors were rational, and as a consequence the overconfidence bias does not affect informational efficiency, price volatility, rational traders’ expected profits or their welfare. Intuitively, as overconfidence goes up, so does price informativeness, which makes rational agents cut their information acquisition activities, effectively undoing the standard effect of more aggressive trading by the overconfident. The main intuition of the paper, if not the irrelevance result, is shown to be robust to different model specifications.We would like to thank Alberto Bisin, Xavier Freixas, Ken French, Moshe Kim, Jose Marín, and Terrance Odean for comments on an early draft, as well as an anonymous referee and seminar participants at HEC Geneva, the 2004 EFA meetings, the 2004 European Econometric Society meetings and the 2005 SAET conference. Diego García and Branko Urošević gratefully acknowledge financial support by SECCF (Belgrade).     

Asset price volatility and trading volume with rational beliefs

Summary. This paper develops a model of speculative trading in a large economy with a continuum of investors. In our model the investors are assumed to have diverse beliefs which are rational in the sense of being compatible with observed data. We demonstrate the existence of price amplification effects and show that the equilibrium prices can be higher or lower than the rational expectation equilibrium price. It is also shown that trading volume is positively related to the directions of price changes. Moreover, we study how asset price volatility and trading volume are influenced by belief structures, short selling constraints and the amount of fund available for investment.Received: 23 January 2003, Revised: 30 April 2003, JEL Classification Numbers: D84, G12.We are grateful to Professors Mordecai Kurz, Kenneth Arrow, Kenneth Judd, Carsten Nielsen, Maurizio Motolese, Mark Garmaise, Jean-Michel Grandmont, Peter Hammond, Karl Shell, Jan Werner and participants of the Society for the Advancement of Economic Theory (SAET) Conference and Stanford Institute of Theoretical Economics (SITE) Conference for many helpful suggestions. Correspondence to: H.-M. Wu     

Informed trade,uninformed trade and stock price delay

The probability of informed trading (PIN), a measure of information-based trading risk, has been broadly applied to empirical studies on asset pricing. However, it is still controversial whether PIN measures exclusively the risk of firm-specific private information or it also captures the private interpretation of market wide public information. This article examines the relevance of PIN to the delayed response of stock prices to market-wide information. We find that PIN significantly explains individual stock price delay even controlling for size, liquidity and risk, and low-PIN stock prices adjust to market information more rapidly not only because of a notably high level of informed trading but also an even much higher level of uninformed trading. Our findings support the notion that PIN also captures the private skilled interpretation of public common factor information by sophisticated investors, and provide new empirical evidence on how information-based trading affects the speed at which stock prices adjust to information.     

Market reaction to second-hand news: inside the attention-grabbing hypothesis

This article investigates whether the market reaction to second-hand information is due to price pressure or information dissemination. We use the perspective of attention grabbing to analyse the market reaction to the dissemination of analysts’ recommendations published in print media. This perspective is able to explain the asymmetric market reaction to ‘buy’ and ‘sell’ advice, which is difficult to rationalize within the price pressure hypothesis. We base our empirical analysis on the content of a weekly column in the most important Italian financial newspaper, which publishes past information and analysts’ recommendations on listed companies. Our findings show asymmetric price and volume reactions on the publication day. Contrary to previous evidence, we document a positive relationship between the number of analysts quoted in the column and the price (volume) increase associated with positive recommendations. Because the weekly columns seem to simply attract investors’ attention, with no additional new information, observing a reaction positively related to the column’s salience (proxied by the number of quoted analysts) is natural. In addition, we find that the market reaction is higher when the order size is lower, i.e., when individual investors’ trades constitute a higher fraction of the total trading activity in the market.     

Investor sentiment,information and asset pricing model

We present an asset pricing model with investor sentiment and information, which shows that the investor sentiment has a systematic and significant impact on the asset price. The equilibrium price's rational term drives the asset price to the rational, and the sentiment term leads to the asset price deviating from it. In our model, the proportion of sentiment investors and the information quality could amplify the sentiment shock on the asset price. Finally, the information is fully incorporated into prices when sentiment investors learn from prices. The model could offer a partial explanation of some financial anomalies: price bubbles, high volatility, asset prices' momentum effect and reversal effect.     

融券约束和市场定价效率*——基于我国股票市场转融通的准自然实验证据

本文从融券约束的视角出发，研究我国股票市场融券机制对标的股票价格发现效率的影响。相比于融券交易量，融券约束可以更好地识别融券机制的作用。因为它可以从交易渠道、信息渠道、外部监管渠道对股价产生影响。笔者利用转融通的实施作为准自然实验，识别出了融券约束放松后标的股票价格发现效率的变化。实证结果显示融券约束放松后：（1）在市场下跌的情况下股价的共同趋势增强，意味着此时股价中包含的个股特质性信息含量降低，而市场上涨时则不存在这种效应；（2）股价对市场信息的反应速度增快；（3）股价更加接近随机游走，即股价的可预测性降低。本文的政策启示是，适当降低融券约束、扩大机构投资者比例、保持较高的融券交易准入门槛以及加强投资者教育可以促进融券机制发挥积极作用。     

TRADER TYPE EFFECTS ON THE VOLATILITY‐VOLUME RELATIONSHIP EVIDENCE FROM THE KOSPI 200 INDEX FUTURES MARKET

We investigate whether the trading activity generated by investors with different access to information and trading motives has positive or negative impact on index futures volatility. Surprises in non‐member institutional, individual and foreign investors' trading volume are positively associated with volatility in most of the cases. For member institutional investors, unexpected trading volume is positively related to volatility. Long‐run changes in the trading activity also affect volatility differently across trader types. Finally, allowing for time‐to‐maturity effects, surprises in open interest are associated with more volatility towards contract expiration, contrary to the negative effect we find during normal times.     

Investor sentiment,trading behavior and stock returns

This article examines how investor sentiment and trading behaviour affect asset returns. By analysing the unique stock trading dataset of the Korean market, we find that high investor sentiment induces higher stock market returns. We also find that institutional (individual) trades are positively (negatively) associated with stock returns, suggesting the information superiority (inferiority) of institutional (individual) investors. Investor sentiment generally plays a more important role in explaining stock market returns than investor trading behaviour.     

TRADING AMBIGUITY: A TALE OF TWO HETEROGENEITIES

We consider markets with heterogeneously ambiguous assets and heterogeneously ambiguity-averse investors whose preferences are a parsimonious extension of the mean–variance framework. We study portfolio choice and trade upon arrival of public information, and show systematic departures from the predictions of standard theory, that occur in the direction of empirical regularities. In particular, our theory speaks to several phenomena in a unified fashion: the asset allocation puzzle, the observation that earnings announcements are followed by significant trading volume with small price change, and that increases in uncertainty are positively associated with increased trading activity and portfolio rebalancing toward safer assets.     

Relationship between the trading behavior of three institutional investors and Taiwan Stock Index futures returns

The relations between institutional investors' behavior and futures returns are examined in this study. Evidence suggests that net trading volume by foreign investors and investment trust have forecasting power for futures returns. In addition, the study applies a time-varying parameter vector autoregressive (TVP-VAR) approach to estimate the relative effects of trading behavior by institutional investors on futures returns over time. The impact of open interest by three institutional investors is decreasing over the recent years. This implies that the value for open interest information from three major institutional investors is gradually declining in Taiwan.     

Information Markets and the Comovement of Asset Prices

Traditional asset pricing models predict that covariance between prices of different assets should be lower than what we observe in the data. This paper introduces markets for information that generate high price covariance within a rational expectations framework. When information is costly, rational investors only buy information about a subset of the assets. Because information production has high fixed costs, competitive producers charge more for low-demand information than for high-demand information. The low price of high-demand information makes investors want to purchase the same information that others are purchasing. When investors price assets using a common subset of information, news about one asset affects the other assets' prices; asset prices comove. The cross-sectional and time-series properties of comovement are consistent with this explanation.     

Price Limits, Information Acquisition, and Bid–ask Spreads: Theory and Evidence

A number of futures markets use price limits which, in effect, preclude trade from occurring at prices outside certain exogenous bounds. Noting that such markets are characterized by heterogeneously informed traders, whereas previous work on price limits assumes symmetrically informed traders, we examine the effects of price limits in a setting where market participants are asymmetrically informed. We find that imposing price limits generally lowers the quality of information acquired in equilibrium, but lowers bid–ask spreads as well. Thus, depending on the relative weights placed by society on liquidity versus price efficiency, there may exist a set of price limits that are most efficient in achieving a trade-off between liquidity and informational efficiency. We perform empirical tests of some implications of the model using cross-sectional data on price limits. We find that price limits are strongly negatively related to both price volatility and trading volume. Though other explanations for our empirical findings cannot be ruled out, these results are not inconsistent with the model's implication that price limits should be tighter for contracts which offer greater profit potential for informed traders.     

The Neural Inhibition of Learning Increases Asset Market Bubbles: Experimental Evidence

The authors tested a leading theory of bubble formation, insufficient learning, in a laboratory asset market using a drug, Naltrexone, which inhibits reinforcement learning. We found that asset price bubbles in Naltrexone sessions were larger compared with placebo sessions, averaging 60% higher in amplitude and 77% larger in the deviation from fundamental value in the final 12-period trading round. There was no difference between conditions in understanding of the trading rules, overconfidence, or confusion. Participants on Naltrexone appeared unable to determine appropriate trading strategies as prices changed. The findings indicate that specific neural mechanism of reinforcement learning is involved in the formation of asset market bubbles.     

Search and endogenous concentration of liquidity in asset markets

We develop a search-based model of asset trading, in which investors of different horizons can invest in two assets with identical payoffs. The asset markets are partially segmented: buyers can search for only one asset, but can decide which one. We show the existence of a “clientele’’ equilibrium where all short-horizon investors search for the same asset. This asset has more buyers and sellers, lower search times, and trades at a higher price relative to its identical-payoff counterpart. The clientele equilibrium dominates the one where all investor types split equally across assets, implying that the concentration of liquidity is socially desirable.     

THE DYNAMIC RELATION BETWEEN RETURNS,TRADING VOLUME,AND VOLATILITY: LESSONS FROM SPILLOVERS BETWEEN ASIA AND THE UNITED STATES

This paper investigates the dynamic relationship between index returns, return volatility, and trading volume for eight Asian markets and the US. We find cross‐border spillovers in returns to be non‐existent, spillovers in absolute returns between Asia and the US to be strong in both directions, and spillovers in volatility to run from Asia to the US. Trading volume, especially on the Asian markets, depends on shocks in domestic and foreign returns as well as on volatility, especially those shocks originating in the US. However, only weak evidence is found for trading volume influencing other variables. In the light of the theoretical models, these results suggest sequential information arrivals, with investors being overconfident and applying positive feedback strategy. Furthermore, new information causes price volatility to rise due to differences in its interpretation among traders, but the subsequent market reaction takes the form of adjustment in price level, not volatility. Lastly, the intensity of cross‐border spillovers seems to have increased following the 1997 crisis, which we interpret as evidence of increased noisiness in prices and diversity in opinions about news originating abroad. Our findings might also help to understand the nature of financial crises, to predict their further developments and consequences.     

WHY DO PRICE SPREADS BETWEEN DOMESTIC SHARES AND THEIR ADRS VARY OVER TIME?

Abstract. The exchange translated price spreads between domestic stocks and their American depositary receipts (ADRs) are conventionally ascribed to market friction. However, price spreads vary over time and sometimes fluctuate dramatically, which is hardly explainable by friction costs and implies the existence of arbitrage opportunities. This study hypothesizes that changes in trading volume and macro events generate heterogeneous expectations between two markets, which augments price spreads. Using a sample of 37 dual‐listing firms of six Far Eastern countries, we confirm this hypothesis by showing that domestic volume and macro events shift price spreads. We also find that: (i) the liberalization of capital control in Korea and Taiwan slashed price spreads; and (ii) investors can profit by trading Hong Kong stocks and ADRs.