ECONOMETRIC TESTS OF ASSET PRICE BUBBLES: TAKING STOCK*

Abstract Can asset price bubbles be detected? This survey of econometric tests of asset price bubbles shows that, despite recent advances, econometric detection of asset price bubbles cannot be achieved with a satisfactory degree of certainty. For each paper that finds evidence of bubbles, there is another one that fits the data equally well without allowing for a bubble. We are still unable to distinguish bubbles from time‐varying or regime‐switching fundamentals, while many small sample econometrics problems of bubble tests remain unresolved.     

Rational asset pricing bubbles and debt constraints

Rational price bubble arises when the price of an asset exceeds the asset’s fundamental value, that is, the present value of future dividend payments. The important result of Santos and Woodford (1997) says that price bubbles cannot exist in equilibrium in the standard dynamic asset pricing model with rational agents facing borrowing constraints as long as assets are in strictly positive supply and the present value of total future resources is finite. This paper explores the possibility of asset price bubbles under endogenous debt constraints induced by limited enforcement of debt repayment. Equilibria with endogenous debt constraints are prone to have infinite present value of total resources. We show that asset price bubbles are likely to exist in such equilibria. Further, we demonstrate that there always exist equilibria with price bubbles on assets in zero supply.     

THE DEBATE ABOUT THE REVIVED BRETTON‐WOODS REGIME: A SURVEY AND EXTENSION OF THE LITERATURE

This paper surveys the literature dealing with the thesis put forward by Dooley, Folkerts‐Landau and Garber (DFG) that the present constellation of global exchange‐rate arrangements constitutes a revived Bretton‐Woods regime. DFG also argue that the revived regime will be sustainable, despite its large global imbalances. While much of the literature generated by DFG's thesis points to specific differences between the earlier regime and revived regime that render the latter unstable, we argue that an underlying similarity between the two regimes renders the revived regime unstable. Specifically, to the extent that the present system constitutes a revived Bretton‐Woods system, it is vulnerable to the same set of destabilizing forces – including asset‐price bubbles and global financial crises – that marked the latter years of the earlier regime, leading to its breakdown. We extend the Markov switching model to examine the relation between global liquidity and commodity prices. We find an evidence of commodity‐price bubbles in both the latter stages of the earlier Bretton‐Woods regime and the revived regime.     

Adverse effects of leverage and short-selling constraints in a financial market model with heterogeneous agents

This paper investigates the impact of leverage and short-selling constraints on financial market stability. Investors׳ demand is modelled in a well-known asset pricing model with heterogeneous beliefs. In particular, I generalise the heterogeneous agents model of Brock and Hommes (1998) and Anufriev and Tuinstra (2013) to allow for leverage constraints as well as a short-selling tax. I consider two examples of adaptive belief systems describing the coevolution of prices and investors׳ beliefs. First, if the market is inhabited by fundamentalist and chartist traders, demand constraints have potential adverse effects and may restrict the stabilising fundamentalist strategy such that mispricing and price volatility increase. Second, if the market is inhabited by fundamentalists, optimists and pessimists with fixed beliefs, demand constraints drive down price volatility, but mispricing remains. The results suggest the stabilising effects of demand constraints in financial markets are limited. Only if asset prices are too high compared to fundamentals, policy makers should consider constraining leverage ratios in order to deflate financial bubbles.     

A remark on the fiscal theory of price determination

The fiscal theory of price determination asserts that the price level is determined by the ratio of nominal public debt to the present value of real primary surpluses. To show its fragility, we describe a simple monetary economy with an infinitely lived real productive asset. Under the hypotheses of the fiscal theory, speculative bubbles occur at equilibrium, thus leading to an indeterminate price level.     

资产泡沫与经济增长之间关系的实证研究

将资产泡沫分为生产性资产泡沫和非生产性资产泡沫,前者是促进经济增长的,而后者是抑制经济增长的。在现实中,生产性资产泡沫表现为股市泡沫,非生产性资产泡沫表现为房地产泡沫。分别以美国和日本为例进行了实证研究,并得到了支持其结论的结果。     

Duration dependence testing for speculative bubbles

Prior research has employed a number of methods to test for speculative bubbles in asset prices, including a method based on the concept of duration dependence. This study explores whether duration dependence tests for speculative bubbles are sensitive to specification decisions. Our results question the efficacy of using measures of duration dependence to test for speculative bubbles. In particular, we find that evidence of duration dependence is sensitive to the method of correcting for discrete observation of continuous duration, the use of value-weighted versus equally weighted portfolios, and the use of monthly versus weekly runs of abnormal returns. (JEL C41, G12)     

A remark on the fiscal theory of price determination

The fiscal theory of price determination asserts that the price level is determined by the ratio of nominal public debt to the present value of real primary surpluses. To show its fragility, we describe a simple monetary economy with an infinitely lived real productive asset. Under the hypotheses of the fiscal theory, speculative bubbles occur at equilibrium, thus leading to an indeterminate price level.     

Systemic risk of Chinese financial institutions and asset price bubbles

Although there has not been a large-scale systemic crisis in China, high-risk financial events have occurred continuously in recent years. This research thus creatively analyzes the determinants of systemic risk for Chinese financial institutions from the view of asset price bubbles. First, we identify bubbles in the China stock and real estate markets on the basis of the generalized sup Augmented Dickey-Fuller (GSADF) model and explain the reasons for bubble formations according to the stage of China's economic development and policies implementation. At this stage, considering the differences in economic development levels of different cities, the real estate bubbles in the first, second and third tier cities and the whole country were innovatively identified. Second, on the basis of the DCG-GARCH-CoVaR model to measure the systemic risk of listed financial institutions in China and to classify institutions, the results show that the main source of such risk is the banking sector. Furthermore, by constructing regression models, stock market bubbles and real estate bubbles both positively correlate with systemic risk throughout the sample period. Meanwhile, the impact of bubbles on the systemic risk of different types of financial institutions was taken into account so that regulators prioritized different types of institutions with different characteristics when faced with decisions. Finally, we provide macro-prudential policy advice to regulators in order to weaken the impact of bubbles on financial stability to avoid systemic crises.     

Monetary policy and asset prices in an open economy

This paper examines whether central banks should respond to asset price fluctuations in a two-country sticky price model. We compare a monetary policy rule that targets both domestic asset prices and foreign asset prices with several alternative monetary policy rules. This paper shows that this policy rule can produce preferable outcomes because the domestic central bank incorporates important information that both domestic and foreign asset prices possess into its monetary policy. Our model suggests that central banks should consider both domestic and foreign asset prices in a two country framework with asset price fluctuations.     

Diagnosing housing fever with an econometric thermometer

Housing fever is a popular term to describe an overheated housing market or housing price bubble. Like other financial asset bubbles, housing fever can inflict harm on the real economy, as indeed the U.S. housing bubble did in the period following 2006 leading up to the general financial crisis and great recession. One contribution that econometricians can make to minimize the harm created by a housing bubble is to provide a quantitative “thermometer” for diagnosing ongoing housing fever. Early diagnosis can enable prompt and effective policy action that reduces long-term damage to the real economy. This paper provides a selective review of the relevant literature on econometric methods for identifying housing bubbles together with some new methods of research and an empirical application. We first present a technical definition of a housing bubble that facilitates empirical work and discuss significant difficulties encountered in practical work and the solutions that have been proposed in the past literature. A major challenge in all econometric identification procedures is to assess prices in relation to fundamentals, which requires measurement of fundamentals. One solution to address this challenge is to estimate the fundamental component from an underlying structural relationship involving measurable variables. A second aim of the paper is to improve the estimation accuracy of fundamentals by means of an easy-to-implement reduced-form approach. Since many of the relevant variables that determine fundamentals are nonstationary and interdependent we use the endogenous instrumental variable based method (IVX) to estimate the reduced-form model to reduce the finite sample bias which arises from highly persistent regressors and endogeneity. The recursive evolving test proposed by Phillips, Shi, and Yu (PSY) is applied to the estimated nonfundamental component for the identification of speculative bubbles. The new bubble test developed here is referred to as PSY-IVX. An empirical application to the eight Australian capital city housing markets over the period 1999–2017 shows that bubble testing results are sensitive to different ways of controlling for fundamentals and highlights the importance of accurate estimation of these housing market fundamentals.     

股票价格低于每股净资产的影响因素分析——来自中国A股上市公司的经验证据

破净指股票价格跌破每股净资产,是股票价格与每股净资产关系的一种极端表现。本文以1 059家A股上市公司为样本,采用修正的Ohlson模型,分组对股价破净的影响因素进行研究。结果发现:对于业绩为正的非ST企业而言,公司规模大、上市时间早、机构投资者持股比例低的国有企业容易破净;ST企业的股票价格虽下跌,但其重组捷径和壳资源改变了投资者的预期,使ST企业不破净或较少破净。     

Asset price volatility and banks

This paper examines the operation of Diamond–Dybvig banks when depositors have access to the asset market. Previous studies have shown that banks are redundant in this environment since it is impossible to prevent the strategic withdrawals. This paper shows that the strategic withdrawals can be prevented if the market risk, due to asset price volatility, is considered. Banks provide deterministic returns to the depositors since the aggregate withdrawals are predictable, and therefore, banks can choose the portfolio such that no asset liquidation is involved. However, an individual consumer with stochastic liquidity need is vulnerable to the price volatility if he holds the asset directly. Therefore, banks improve the consumers’ welfare by providing the insurance against not only the liquidity shock but also the market risk. Banks are not redundant.     

Contagion testing in frontier markets under alternative stressful S&P 500 market scenarios

We use alternative approaches to identify stable and stressful scenarios in the S&P 500 market, to offer a new perspective for constructing contagion tests in recipient frontier markets vulnerable to disturbances from this source market. The S&P 500 market is decomposed into discrete conditions of: (1) tranquil versus turbulent volatility; (2) bull versus bear market phases; (3) normal periods versus asset bubbles and crashes. Based on these identified scenarios, we use various co-moment contagion tests to analyse the changing relationship between the S&P 500 market and major frontier markets in the Caribbean region that have prominent trade related exposure to the US. Our findings show that, outside of the events of the Great Recession, the Caribbean stock exchanges are largely independent of the S&P 500 market.     

Sectoral bubbles,misallocation, and endogenous growth

Stock price bubbles are often on productive assets and occur in a sector of the economy. In addition, their occurrence is often accompanied by credit booms. Incorporating these features, we provide a two-sector endogenous growth model with credit-driven stock price bubbles. Bubbles have a credit easing effect in that they relax collateral constraints and improve investment efficiency. Sectoral bubbles also have a capital reallocation effect in the sense that bubbles in a sector attract more capital to be reallocated to that sector. Their impact on economic growth depends on the interplay between these two effects. Bubbles may misallocate resources across sectors and reduce welfare.     

On the ingredients for bubble formation: Informed traders and communication

Bubbles in asset markets have been documented in numerous experiments. Most experiments in which bubbles occur feature a declining fundamental value. This feature has been criticized for being atypical of real financial markets. Here, we experimentally study other ingredients for bubble formation that are common in such markets, namely the existence of inside information and communication among traders. We find that bubbles and mirages can occur if these additional ingredients are present. In particular, the mere possibility that some traders are better informed than others can create bubbles. Surprisingly, communication turns out to be counterproductive for bubble formation.     

Asset price and wealth dynamics in a financial market with heterogeneous agents

This paper considers a discrete-time model of a financial market with one risky asset and one risk-free asset, where the asset price and wealth dynamics are determined by the interaction of two groups of agents, fundamentalists and chartists. In each period each group allocates its wealth between the risky asset and the safe asset according to myopic expected utility maximization, but the two groups have heterogeneous beliefs about the price change over the next period: the chartists are trend extrapolators, while the fundamentalists expect that the price will return to the fundamental. We assume that investors’ optimal demand for the risky asset depends on wealth, as a result of CRRA utility. A market maker is assumed to adjust the market price at the end of each trading period, based on excess demand and on changes of the underlying reference price. The model results in a nonlinear discrete-time dynamical system, with growing price and wealth processes, but it is reduced to a stationary system in terms of asset returns and wealth shares of the two groups. It is shown that the long-run market dynamics are highly dependent on the parameters which characterize agents’ behaviour as well as on the initial condition. Moreover, for wide ranges of the parameters a (locally) stable fundamental steady state coexists with a stable ‘non-fundamental’ steady state, or with a stable closed orbit, where only chartists survive in the long run: such cases require the numerical and graphical investigation of the basins of attraction. Other dynamic scenarios include periodic orbits and more complex attractors, where in general both types of agents survive in the long run, with time-varying wealth fractions.     

Maritime businesses: volatile stock prices and market valuation inefficiencies

This paper examines 12 maritime equity price series for behavioral stability and efficient market pricing for the 1989–2002 period. Five self-affine fractal analysis techniques for estimating the Hurst exponent, Mandelbrot–Lévy characteristic exponent, and fractal dimension are employed to explore the price series fractal properties. Techniques employed are rescaled-range analysis, power-spectral density analysis, roughness–length analysis, the variogram or structure function method, and wavelet analysis. Formal hypothesis tests provide evidence of a change in market behavior between the 1989–1994 and 1995–2002 periods. Hypothesis tests also provide evidence against efficient valuation of the maritime businesses sampled, supporting the multifractal model of asset returns (MMAR), and disconfirming the weak form of the Efficient Market Hypothesis (EMH). Strong evidence is presented for antipersistence of some maritime equities in the sample, suggesting market participants habitually overreact to new information, and never learn not to. An important implication of this finding is that financial derivatives based on the sampled equities cannot be efficiently priced.     

中国十大宜居城市房地产价格泡沫度的实证研究

本文通过单位根ADF检验,对我国十大宜居城市中的九个城市（剔除桂林,数据不可得）的房地产价格泡沫进行了初步检验,结果显示除青岛外其他城市房地产价格都面临着不同程度的泡沫。然后通过建立时变风险溢价模型和三变量VAR模型,对除青岛以外的剩余城市的房地产价格泡沫进行了度量,结果显示：上海、大连、北京、广州、成都、杭州、珠海和厦门的房地产市场都存在着不同程度的泡沫,其中北京、杭州和珠海的房地产市场泡沫已经达到了30％以上,而上海、大连和厦门的房地产市场泡沫在20％以上,成都和广州的房地产市场泡沫也在10％以上。使用该方法可以度量任何一个地区、省份、市区的房地产价格泡沫度,可以为房地产商、购房人和中央及地方政府提供相应的决策依据。     

Impact of volatility jumps in a mean-reverting model: Derivative pricing and empirical evidence

This paper investigates the critical role of volatility jumps under mean reversion models. Based on the empirical tests conducted on the historical prices of commodities, we demonstrate that allowing for the presence of jumps in volatility in addition to price jumps is a crucial factor when confronting non-Gaussian return distributions. By employing the particle filtering method, a comparison of results drawn among several mean-reverting models suggests that incorporating volatility jumps ensures an improved fit to the data. We infer further empirical evidence for the existence of volatility jumps from the possible paths of filtered state variables. Our numerical results indicate that volatility jumps significantly affect the level and shape of implied volatility smiles. Finally, we consider the pricing of options under the mean reversion model, where the underlying asset price and its volatility both have jump components.