Temporary bubbles

This article studies the dynamics of an overlapping generations model with capital, money and cash-in-advance constraints. The economy can exhibit two different regimes. In the first one, the cash-in-advance constraint is binding and money is a dominated asset. In the second one, the constraint is strictly satisfied and money has the same return as capital. When the second regime holds on a finite number of periods, we say that the economy experiences a temporary bubble. We prove that temporary bubbles can exist in an economy, which would experience under-accumulation without money. We also show that cyclical bubbles may occur.     

Intrinsic bubbles and asset price volatility

Summary Under what conditions is the price of a bubbly asset more (less) volatile than the asset's market fundamental? The answer depends on agents' attitudes towards risk. If higher current consumption makes agents more (less) risk averse in the future, then the bubbly asset price fluctuates less (more) than the fundamental. This result shows that the interaction between intrinsic bubbles and asset fundamentals critically depends on a feature of the utility function that does not appear in standard models with time-separable utility.Financial support from the Department of Economics at Texas A&M University, the Office for International Coordination at Texas A&M University, and the Deutsche Forschungsgemeinschaft, Sonderforschungsbereich 303 at the University of Bonn, is gratefully acknowledged. The views expressed are those of the authors and do not necessarily represent those of the International Monetary Fund.     

Bubbles as payoffs at infinity

Summary We define rational bubbles to be securities with payoffs occurring in the infinitely distant future and investigate the behavior of bubbles values. We extend our analysis to a setting of uncertainty. In an infinite horizon arbitrage-free model of asset prices, we interpret the money market account as the value of a particular bubble; a similar interpretation holds for other assets related to the state-price deflator and to payoffs on bonds maturing in the distant future. We present three applications of this characterization of bubbles.This paper was circulated under the title Stochastic bubbles in Markov economies. We acknowledge with gratitude numerous conversations with Mark Fisher, the editorial advice of David Levine and the useful comments of anonymous referees. This paper should not be interpreted as reflecting the views of the Board of Governors of the Federal Reserve System or its staff.     

Asset Bubbles,Unemployment, and a Financial Crisis

A tractable growth model with asset bubbles is presented to demonstrate that a financial crisis caused by a bubble bursting increases unemployment rates. A bubbly asset, which is intrinsically useless, has a positive market value because purchasing the asset is a sole saving method for agents who draw insufficiently low productivity, whereas selling the asset is a fund-raising method for agents who draw high productivity to initiate an investment project. The presence of asset bubbles corrects allocative inefficiency regarding production resources, relocating investment resources from low-productivity agents to high-productivity agents. Accordingly, the presence of asset bubbles can promote capital accumulation. As capital accumulates and output increases, the number of vacant positions increases because firms acquire more funds to cover a search cost. As a result, firms are incentivized to increase employment. However, extrinsic uncertainty may burst asset bubbles and cause a self-fulfilling financial crisis, which is followed by increased unemployment.     

What determines simultaneous asset bubbles? An empirical analysis

The recent global financial crisis demonstrated that the simultaneous collapse of asset bubbles in different countries is a major challenge for monetary policy. In order to evaluate determinants of these simultaneous asset bubbles, we detect rational asset bubbles in corporate equity and real estate markets worldwide using forward recursive right-sided ADF tests. Then we create dummy variables for simultaneous asset bubbles and analyse potential determinants using gravity models and spatial economics. Our empirical analysis suggests that simultaneous asset bubbles depend positively upon potential asset demand, capital account openness, monetary conditions, cultural similarities and negatively upon informational frictions and exchange rate flexibility. These findings imply that monetary policy can impede the probability of simultaneous asset bubbles by ensuring sound monetary conditions and choosing a flexible exchange regime.     

资产价格泡沫与货币政策应对——事先行动还是事后反应

资产价格泡沫的产生原因是多方面的,早期的研究更多地认为资产泡沫来自于投资者的非理性因素,但是随着金融自由化进程的推进,与经济金融发展水平不相适应的金融自由化也成为资产泡沫产生的一个重要原因。而对于资产价格泡沫的货币政策应对一直存在争议,一些学者主张货币政策应该忽略资产价格,而另一些学者则主张货币政策应该对资产价格作出反应。本文基于后一种观点,来探讨当预期资产价格将出现泡沫时,货币政策是该事先行动还是事后反应,为此,本文引入产出跨期配置的理论,来阐述货币政策应对资产价格泡沫的决策模型。     

GROWTH AND BUBBLES WITH CONSUMPTION EXTERNALITIES*

This paper explores the role of consumption externalities in an overlapping generations economy with capital accumulation. If consumers in each generation are concerned with other agents’ consumption behaviours, there exist intergenerational as well as intragenerational consumption externalities. It is the presence of intergenreational consumption externalities that may produce fundamental effects both on equilibrium dynamics and on steady‐state characterization of the economy. This paper demonstrates this fact in the context of a simple model of endogenously growing, overlapping‐generations economy with or without asset bubbles.     

预算软约束与资产价格理性泡沫

文章将预算软约束引入资产价格理性泡沫的分析之中,在给出一个预算软约束情形下资产均衡价格决定模型的基础上,得出了资产价格理性泡沫的表达式.模型分析表明,当存在预算软约束时风险资产的理性泡沫为正;同时,风险资产对应企业面临的预算软约束越大,该风险资产价格中的理性泡沫越大.     

PRODUCE OR SPECULATE? ASSET BUBBLES,OCCUPATIONAL CHOICE,AND EFFICIENCY*

We study the effects of rational asset bubbles in an overlapping‐generations economy where asset trading requires specialized intermediaries and agents freely choose between working in the production or the financial sector. Frictions in the market for deposits create rents in the financial sector that affect agents’ occupational choices. When rents are large, the private gains associated with trading bubbles lead too many agents to become speculators, causing bubbles to lose their efficiency properties. Moreover, if speculation can be carried out by skilled labor only, then bubbles displace skilled workers away from the productive sector and raise income inequalities.     

Growth Effects of Bubbles in an Endogenous Growth Model

This paper examines the possibility of the existence of bubbles and their effects on the growth rate by using an endogenous growth model. A necessary and sufficient condition for the existence of steady-state equilibrium with bubbles is provided. If non-zero rates of the useless asset supply are allowed, a steady-state equilibrium with bubbles exists even if the growth rate of the bubbleless equilibrium is lower than the market interest rate. The growth rate in the steady state with bubbles depends positively on the supply rate of the useless asset. Dynamic properties of bubbles are also analysed.
JEL Classification Numbers: E52, O41, O42.     

Welfare effects of bubbles in an endogenous growth model

This paper examines welfare effects of asset bubbles in an endogenous growth model with overlapping generations. In our model, a steady-state equilibrium with bubbles exists only if the presence of bubbles raises the welfare level of the initial generation. Bubbles can be beneficial to generations born at relatively early dates, whereas they reduce the welfare level of sufficiently distant future generations. Increasing the rate of supply of the useless asset improves the lifetime utilities of future generations.     

资产价格泡沫研究述评:实验金融学视角

本文从实验金融学的视角介绍了资产泡沫最新的定义和分类,阐述了投机性泡沫、理性泡沫与非理性泡沫之间的区别和联系,着重从信息对称、信息不对称、有限套利泡沫、异质信念和实验金融五个方面系统评述了资产价格泡沫理论的发展历程和新进展,指出该领域进一步的研究方向和中国开展资产价格泡沫研究的重要意义。研究表明,随着现代金融学的高速发展,学界对资产泡沫的研究日益深入。特别是非理性和实验金融学视角的引入,突破了传统金融框架的束缚,为这一课题研究带来了新的认知和理解。即便如此,目前仍无法根除资产泡沫产生的可能性。很多相关问题,如资产泡沫产生的时间和根本原因,仍然等待着学者们去探索和研究。     

Uniqueness of asset prices in an exchange economy with unbounded utility

Summary. This paper studies conditions under which the price of an asset is uniquely determined by its fundamental value – i.e., no bubbles can arise – in Lucas-type asset pricing models with unbounded utility. After discussing Gilles and LeRoy's (1992) example, we construct an example of a two-period, representative agent economy to demonstrate that bubbles can arise in a standard model if utility is unbounded below, in which case the stochastic Euler equation may be violated. In an infinite horizon framework, we show that bubbles cannot arise if the optimal sequence of asset holdings can be lowered uniformly without incurring an infinite utility loss. Using this result, we develop conditions for the nonexistence of bubbles. The conditions depend exclusively on the asymptotic behavior of marginal utility at zero and infinity. They are satisfied by many unbounded utility functions, including the entire CRRA (constant relative risk aversion) class. The Appendix provides a complete market version of our two-period example. Received: January 22, 1996; revised version: February 18, 1997     

中国股市的理性泡沫

传统理论通常把证券市场的泡沫与投资者的非理性行为混为一谈。近期的研究却表明在一个完全理性的市场中 ,泡沫依然可以出现。本文首先对我国证券市场存在理性泡沫的可能性提出多种理论解释 ,认为下列原因导致了我国证券市场泡沫的存在 :( 1 )上市审批制 ;( 2 )可供投资的证券种类少 ;( 3 )政府的托市行为 ;( 4)卖空机制的缺乏 ;( 5)套利机制缺乏有效性 ;( 6)上市公司很少分红 ,投资者买卖股票只是为了获得买卖差价。其次 ,我们通过分析所得的结果 ,提出应对理性泡沫的政策措施。     

FUTURES MARKETS AND BUBBLE FORMATION IN EXPERIMENTAL ASSET MARKETS*

Abstract. We construct asset markets of the type studied in Smith et al. (1988) , in which price bubbles and crashes are widely observed. In addition to a spot market, there are futures markets in operation, one maturing at the beginning of each period of the life of the asset. We find that when futures markets are present, bubbles do not occur in the spot markets. The futures markets seem to reduce the speculation and the decision errors that appear to give rise to price bubbles in experimental asset markets.     

Compensation schemes,liquidity provision,and asset prices: an experimental analysis

In an experimental setting in which investors can entrust their money to traders, we investigate how compensation schemes affect liquidity provision and asset prices, two outcomes that are important for financial stability. Compensation schemes can drive a wedge between how investors and traders value the asset. Limited liability makes traders value the asset more than investors. To limit losses, investors should thus restrict liquidity provision to force traders to trade at a lower price. By contrast, bonus caps make traders value the asset less than investors. This should encourage liquidity provision and increase prices. In contrast to these predictions, we find that under limited liability investors increase liquidity provision and asset price bubbles are larger. Bonus caps have no clear effect on liquidity provision and they fail to tame bubbles. Overall, giving traders skin in the game fosters financial stability.     

Quantitative easing and asset bubbles

Expansionary monetary policy is necessary to respond to financial crises. However, if Central Bank asset purchase initiatives are too large or last too long, they can lead to explosive increases in asset prices which add to the risk of a future crisis. This article employs two models including the Campbell–Shiller and Generalized Supremum Augmented Dickey Fuller techniques to search for bubbles in the US equity, housing and bond markets over the past eight years. Although, we find that prices in equities and housing have risen following Federal Reserve intervention, there is little indication of asset price bubbles. There is evidence of explosive bond price increases from September of 2011 to February of 2013.     

Bubbles and capital flows

This paper presents a stylized model of international trade and asset price bubbles. Its central insight is that bubbles tend to appear and expand in countries where productivity is low relative to the rest of the world. These bubbles absorb local savings, eliminating inefficient investments and liberating resources that are in part used to invest in high-productivity countries. Through this channel, bubbles act as a substitute for international capital flows, improving the international allocation of investment and reducing rate-of-return differentials across countries. This view of asset price bubbles could eventually provide a simple account of some real world phenomena that have been difficult to model before, such as the recurrence and depth of financial crises or their puzzling tendency to propagate across countries.     

房地产市场理性泡沫分析

在目前我国居民消费平淡、投资渠道有限的情况下 ,发展房地产业 ,拉动内需 ,带动经济整体增长显然有着重要的意义 ,但促进地产市场健康发展的同时也要防止房地产过热 ,尤其是要防止出现严重的地产泡沫。本文以这一迫切的现实问题为导向 ,在回顾和借鉴有关经济“泡沫”的基本理论的基础上 ,构造了一个房地产市场的局部均衡模型 ,给出了地产均衡价格中理性泡沫产生和存在的条件 ,以及导致泡沫破灭的相应条件。在理论上我们的模型为行为人预期、银行信贷以及政府政策在地产泡沫形成中的重要作用提供了一个简明、统一的分析框架。模型的基本结论对历史上几次著名的房地产泡沫也有较强的解释力。在理论和实例分析的基础上 ,文章的最后给出了目前我国房地产市场是否存在泡沫的基本判断 ,以及如何进行宏观调控的几点建议。     

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.