Feedback effects between credit ratings and financial markets

Credit rating agencies often make sharp adjustments in their pronouncements during times of stress in financial markets. These adjustments typically happen with a delay relative to shocks in market prices. Since prices convey information about what market participants are doing and thinking, it is likely that rating agencies take into account market prices when issuing their pronouncements.In order to understand the relationship between credit ratings and financial prices, we develop a model of debt roll-over in which rating agencies incorporate information publicly available in financial markets. We find that (1) rating agencies respond to market prices, i.e. nonfundamental price volatility can shift financing conditions from a low risk spread and high credit rating equilibrium to an equilibrium with high spread and low rating, and (2) rating agencies can anchor expectations about the equilibrium in financial markets, thus serving as an antidote to nonfundamental price volatility.     

Internal rationality, imperfect market knowledge and asset prices

We present a decision theoretic framework in which agents are learning about market behavior and that provides microfoundations for models of adaptive learning. Agents are ‘internally rational’, i.e., maximize discounted expected utility under uncertainty given dynamically consistent subjective beliefs about the future, but agents may not be ‘externally rational’, i.e., may not know the true stochastic process for payoff relevant variables beyond their control. This includes future market outcomes and fundamentals. We apply this approach to a simple asset pricing model and show that the equilibrium stock price is then determined by investors? expectations of the price and dividend in the next period, rather than by expectations of the discounted sum of dividends. As a result, learning about price behavior affects market outcomes, while learning about the discounted sum of dividends is irrelevant for equilibrium prices. Stock prices equal the discounted sum of dividends only after making very strong assumptions about agents? market knowledge.     

When is market incompleteness irrelevant for the price of aggregate risk (and when is it not)?

In a standard incomplete markets model with a continuum of households that have constant relative risk aversion (CRRA) preferences, the absence of insurance markets for idiosyncratic labor income risk has no effect on the premium for aggregate risk if the distribution of idiosyncratic risk is independent of aggregate shocks and aggregate consumption growth is independent over time. In equilibrium, households only use the stock market to smooth consumption; the bond market is inoperative. Furthermore, the cross-sectional distributions of wealth and consumption are not affected by aggregate shocks. These results hold regardless of the persistence of idiosyncratic shocks, even when households face tight solvency constraints. A weaker irrelevance result survives when we allow for predictability in aggregate consumption growth.     

Price Adjustments by a Gasoline Retail Chain

We use daily data to examine price responses in the Swedish gasoline market to changes in the Rotterdam spot price, exchange rates and taxes. The distribution of price adjustments by a leading retail chain, for the period January 1980 to December 1996, is symmetric with no small adjustments. An error correction model shows that, in the short run, prices gradually move towards the long-run equilibrium in response to cost shocks. There is some evidence that, also in the short run, prices are stickier downwards than upwards. Prices respond more rapidly to exchange rate movements than to the spot market price. Our analysis emphasizes that to fully understand price adjustments it is necessary to examine data sets where the sample frequency at least matches that of price adjustments.
JEL classification: C 22; E 31; F 14; L 71     

Land collateral and labor market dynamics in France

The value of land in the balance sheet of French firms correlates positively with their hiring and investment flows. To explore the relationship between these variables, we develop a macroeconomic model with firms that are subject to both credit and labor market frictions. The value of collateral is driven by the forward-looking dynamics of the land price, which reacts endogenously to fundamental and non-fundamental (sunspot) shocks. We calibrate the model to French data and find that land price shocks give rise to significant amplification and hump-shaped responses of investment, vacancies and unemployment that are in line with the data. We show that both the endogenous movements in the firms׳ discount factor and the sluggish response of the land price are key elements that drive the results.     

A behavioral cobweb-like commodity market model with heterogeneous speculators

According to empirical studies, speculators place significant orders in commodity markets and may cause bubbles and crashes. This paper develops a cobweb-like commodity market model that takes into account the behavior of technical and fundamental speculators. We show that interactions between consumers, producers and heterogeneous speculators may produce price dynamics which mimics the cyclical price motion of actual commodity markets, i.e., irregular switches between bullish and bearish price developments. Moreover, we find that the impact of speculators on price dynamics is non-trivial: depending on the market structure, speculative transactions may either be beneficial or harmful for market stability.     

Portfolio choice, attention allocation, and price comovement

This paper models the attention allocation of portfolio investors. Investors choose the composition of their information subject to an information flow constraint. Given their expected investment strategy in the next period, which is to hold a diversified portfolio, in equilibrium investors choose to observe one linear combination of asset payoffs as a private signal. When investors use this private signal to update information about two assets, changes in one asset affect both asset prices and may lead to asset price comovement. The model also has implications for the transmission of volatility shocks between two assets.     

Mini flash crashes: Review,taxonomy and policy responses

We focus on extreme price movements known as mini flash crashes (MFCs). After reviewing the literature, we provide a taxonomy based on a sample of MFCs identified by Nanex on the U.S. financial markets over a three-year period. We detect significant differences between crashes and exchanges. In comparison to ‘up crashes’, we find that ‘down crashes’ exhibit lower absolute returns but have longer duration. We also show that the dynamics of MCFs varies across exchanges. For example, the MFCs on ARCA are on average both less severe and shorter in duration than those on the NASDAQ. We finally review all the key implications of MCFs in terms of public policy.     

Monetary Shocks and Real Exchange Rate Dynamics: a Reappraisal

This paper proposes a two‐country general‐equilibrium model incorporating a tradable sector with pricing‐to‐market as well as a nontradable sector. In that case, real exchange rate fluctuations arise from two sources: changes in the relative price of traded goods, that exemplify deviations from the law of one price, and movements in the relative price of traded to nontraded goods across countries. Our framework sheds light on the propagation mechanisms through which monetary shocks affect the real exchange rate. More specifically, the two components respond in opposite directions to monetary disturbances, which is consistent with data. Besides, the introduction of nontraded goods does not alter the predictive power of monetary shocks because the presence of nontraded goods magnifies the response of the deviation from the law of one price.     

Oil price shocks and stock market activities: Evidence from oil-importing and oil-exporting countries

While the relationship between oil prices and stock markets is of great interest to economists, previous studies do not differentiate oil-exporting countries from oil-importing countries when they investigate the effects of oil price shocks on stock market returns. In this paper, we address this limitation using a structural VAR analysis. Our main findings can be summarized as follows: First, the magnitude, duration, and even direction of response by stock market in a country to oil price shocks highly depend on whether the country is a net importer or exporter in the world oil market, and whether changes in oil price are driven by supply or aggregate demand. Second, the relative contribution of each type of oil price shocks depends on the level of importance of oil to national economy, as well as the net position in oil market and the driving forces of oil price changes. Third, the effects of aggregate demand uncertainty on stock markets in oil-exporting countries are much stronger and more persistent than in oil-importing countries. Finally, positive aggregate and precautionary demand shocks are shown to result in a higher degree of co-movement among the stock markets in oil-exporting countries, but not among those in oil-importing countries.     

Price and quantity regulation in general equilibrium

We consider a general equilibrium model with a production externality (e.g. pollution), where the regulator does not observe firm productivity shocks. We examine quantity (permit) regulation and price (tax) regulation. The quantity of permits issued by the regulator are independent of the productivity shock, since shocks are unobserved. Price regulation implies use of the regulated input is an increasing function of the productivity shock because firms take advantage of a good productivity shock by increasing input use. Thus price regulation generates higher average, but more variable, production. Therefore, we show that in general equilibrium the relative advantage of quantity versus price regulation depends not only on the slopes of marginal benefits and costs, but on general equilibrium effects such as risk aversion. The general equilibrium effects are often more important than the slopes of the marginal benefits and cost curves. In the simplest model, a reasonable risk aversion coefficient implies quantity regulation generates higher welfare regardless of the benefit function.     

THE INFORMATION TECHNOLOGY REVOLUTION AND THE PUZZLING TRENDS IN TOBIN'S AVERAGE q*

The market value of U.S. corporations declined by 50% during 1973–74 and stagnated for the following 15 years. This abrupt decline in market valuations coincided with two technology shocks: (1) the start of the information technology revolution and (2) a sudden slowdown in productivity growth. I use general equilibrium theory to quantify the macroeconomic and asset price implications of these two shocks. The information technology revolution and the productivity slowdown make the theory consistent with the trends of key macroeconomic aggregates from the mid‐1970s to the 1990s, and can also account for most of the drop in market values.     

The possibility of informationally efficient markets

A rational expectations equilibrium with positive demand for financial information does exist under fully revealing asset price—contrary to a wide-held conjecture. Whereas a continuum of investors is inconsistent with fully revealing equilibrium, finitely many investors with average portfolios demand information in equilibrium if they can adjust portfolio size in an additive signal-return model. More information diminishes the expected excess return of a risky asset so that investors who only have a choice of portfolio composition or whose asset endowments strongly differ from the average portfolio are worse off. Under fully revealing price, information market equilibria both with and without information acquisition are Pareto efficient.     

Market power under income polarization

We study the reaction of a monopolistic firm to distributive shocks which lead to income polarization. We show that the movements in the set price and in the sold quantity depend on the served market share. In particular, we identify a region of parameters where the optimal markup moves in the opposite direction of market demand: in this respect, distributive shocks can provide an explanation for countercyclical movements of the markup.     

Front-running dynamics

We integrate a monopolist dual trader into a dynamic model of speculation. In static settings, [J.-C. Rochet, J.-L. Vila, Insider trading without normality, Rev. Econ. Stud. 61 (1994), 131-152] establish an irrelevance result—expected equilibrium outcomes are the same whether the monopolist speculator sees liquidity trade or not; and Roell [Dual-capacity trading and market quality, J. Finan. Intermediation (1990), 105-124] shows that with multiple speculators, dual trading benefits liquidity traders. In dynamic settings, these results are reversed: a front-running speculator exploits knowledge of future liquidity trade, extracting greater profits by smoothing profit extraction intertemporally. Front running introduces positive serial correlation to order flow. Accordingly, market makers discount past order flow in prices, but prices retain the martingale property.     

Choosing price or quantity? The role of delegation and network externalities

We consider a differentiated duopoly and endogenise the firm choice of the strategy variable (price or quantity) to play on the product market in the presence of network externalities. We model this choice by assuming both competition between entrepreneurial (owner-managed) firms and competition between managerial firms in which market decisions are delegated from owners to revenue-concerned managers. While network externalities are shown not to alter the symmetric equilibrium quantity choice arising in the no-delegation case, sufficiently strong network effects allow us to eliminate the multiplicity of equilibria under delegation and lead to a unique equilibrium in which both firms choose price.     

Asset pricing and institutional investors with disagreements

We develop a dynamic asset pricing model with two institutional investors who have benchmark incentives and who disagree about the underlying economy. We derive semi-closed form expressions for all equilibrium quantities. We find that the benchmark stock price increases and the non-benchmark stock price decreases with the benchmark incentives. Furthermore, each stock price decreases with its own disagreement and increases with the other stock disagreement. We also show that there is a positive relationship between the co-movement of the stocks and the benchmark incentives, but that this co-movement is negative with the disagreements, owing to the endogenous risk-sharing mechanisms. Moreover, we find that, when one stock disagreement increases, the optimistic institutional investor always takes positions on this stock by shorting the other stock and the bond in order to hedge against the risk of market changes, in line with the pessimistic investor's beliefs.     

Asset prices, exchange rates and the current account

This paper analyses the role of asset prices in comparison to other factors, in particular exchange rates, as a driver of the US trade balance. It employs a Bayesian structural VAR model that requires imposing only a minimum of economically meaningful sign restrictions. We find that equity market shocks and housing price shocks have been major determinants of the US current account in the past, accounting for up to 30% of the movements of the US trade balance at a horizon of 20 quarters. By contrast, shocks to the real exchange rate have been less relevant, explaining about 9% and exerting a more temporary effect on the US trade balance. Our findings suggest that large exchange rate movements may not necessarily be the key element of an adjustment of today's large current account imbalances, and that in particular relative global asset price changes could be a potent source of adjustment.     

How equilibrium prices reveal information in a time series model with disparately informed, competitive traders

Accommodating asymmetric information in a dynamic asset pricing model is technically challenging due to the problems associated with higher-order expectations. That is, rational investors are forced into a situation where they must forecast the forecasts of other agents. In a dynamic setting, this problem telescopes into the infinite future and the dimension of the relevant state space approaches infinity. By using the frequency domain approach of Whiteman [Linear Rational Expectations Models: A User's Guide, University of Minnesota Press, Minneapolis, 1983] and Kasa [Forecasting the forecasts of others in the frequency domain, Rev. Econ. Dynam. 3 (2000) 726-756], this paper demonstrates how information structures previously believed to preserve asymmetric information in equilibrium, converge to a symmetric information, rational expectations equilibrium. The revealing aspect of the price process lies in the invertibility of the observed state space, which makes it possible for agents to infer the economically fundamental shocks and thus eliminating the need to forecast the forecasts of others.     

Dynamic Equilibrium with Overpriced Put Options

It is a well-known anomaly that prices of put options are too high when options are out-of-the-money. This paper presents a simple general equilibrium model of the market where European put options become substantially overpriced when they are out-of-the-money. Overpricing is due to the presence of short-sale constraints on trading stocks and derivatives, as well as the heterogeneity between investors. We confirm the predicting power of the model by comparing its implications with existing empirical results.