Moral Hazard and Private Monitoring

We clarify the role of mixed strategies and public randomization (sunspots) in sustaining near-efficient outcomes in repeated games with private monitoring. We study a finitely repeated game, where the stage game has multiple equilibria and show that mixed strategies can support partial cooperation, but cannot approximate full cooperation even if monitoring is “almost perfect.” Efficiency requires extensive form correlation, where strategies can condition upon a sunspot at the end of each period. For any finite number of repetitions, we approximate the best equilibrium payoff under perfect monitoring, assuming that monitoring is sufficiently accurate and sunspots are available. Journal of Economic Literature Classification Numbers: C73, D82.     

Correlated equilibria and sunspots

We examine when “sunspots” (uncertainty that has no influence on endowments, preferences, or technology) can affect equilibrium in a simple two-period, two-commodity, two-class economy. We find that such an effect is possibly only if the signals (random variables) that different agents observe are imperfectly correlated (neither perfectly correlated nor independent) and at least one commodity is a Giffen good. For two special cases we characterize the set of equilibria due to sunspots. We conclude by showing the intimate connection between the sunspot equilibria of our finite horizon model and those of the overlapping generations literature.     

Comparative dynamics in a productive asset oligopoly

We build a subgame perfect Nash equilibrium of a common property productive asset oligopoly and analyze separately the impact of a change in the implicit growth rate of the asset and a change in the number of firms exploiting the asset. We show that the steady state level of asset can be a decreasing function of the asset's implicit growth rate. This phenomenon arises when the initial stock of asset is below a certain threshold. In the short-run we show that firms’ exploitation rate can be a decreasing function of the implicit growth rate. We study the impact of a change in the number of firms that share access to the asset. Reducing the number of firms can result, in the long-run, in higher industry production. In the short-run, it can result in an increase of the industry's exploitation and a decrease of the level of the asset's stock.     

The Structure of Sunspot Equilibria: The Role of Multiplicity

This paper examines the structure of sunspot equilibria in a standard two period exchange economy with real assets. We show that for a generic choice of utility functions and endowments, there exists an open set of real asset structures whose payoffs are independent of sunspots such that the economy with this asset structure has a regular sunspot equilibrium. An important implication of our result is that the multiplicity of non-sunspot equilibria is not necessary for the existence of sunspot equilibria. Our technique is general and can be applied to show the existence of sunspot equilibria in other frameworks.     

Price manipulation in an experimental asset market

We analyze in the laboratory whether an uninformed trader is able to manipulate the price of a financial asset by comparing the results of two experimental treatments. In the benchmark treatment, 12 subjects trade a common value asset that takes either a high or a low value. Only three subjects know the actual value of the asset while the market is open for trading. The manipulation treatment is identical to the benchmark treatment apart from the fact that we introduce a computer program as an additional uninformed trader. This robot buys a fixed number of shares in the beginning of a trading period and sells them again afterwards. Our main result shows that the last contract price is significantly higher in the manipulation treatment if the asset takes a low value and that private information is very well disseminated by both markets if the value of the asset is high. Finally, even though this simple manipulation program loses money on average, it is profitable in some instances.     

Remarks on an investor's ‘paradox’

A decreasing absolute risk averse investor invests λW in a safe asset with return s, and (1?λ)W in a risky asset with fixed distribution. An explicit example shows that λ and sλ can decrease as s increases over part of its domain. The existence of such examples has been suggested in earlier articles.     

General equilibrium with nonconvexities and money

In a general-equilibrium economy with nonconvexities, there are sunspot equilibria with good welfare properties; sunspots can ameliorate the effects of the nonconvexities. For these economies, we show that agents act as if they have quasi-linear utility functions. We use this result to construct a new model of monetary exchange along the lines of Lagos and Wright, where trade occurs in both centralized and decentralized markets, but instead of quasi-linear preferences we assume general preferences but with indivisible labor. This suggests that modern monetary theory is more robust than one might have thought. It also constitutes progress on the classic problem of integrating monetary economics and general-equilibrium theory.     

A characterization of the distributions that imply mean—Variance utility functions

If there is a riskless asset, then the distribution of every portfolio is determined by its mean and variance if and only if the random returns are a linear transformation of a spherically distributed random vector. If there is no riskless asset, then the spherically distributed random vector is replaced by a random vector in which the last n ? 1 components are spherically distributed conditional on the first component, which has an arbitrary distribution. If the number of assets is infinite, then there must exist random variables m, v, y, where the distribution of y conditional on m and v is standard normal, such that every portfolio is distributed as some linear combination of m and vy. If there is a riskless asset, then m has zero variance. These distributions exhibit two-fund separability even if the utility function is not concave.     

How do central banks react to wealth composition and asset prices?

We assess the response of monetary policy to developments in asset markets in the euro area, the US and the UK. We estimate the reaction of monetary policy to wealth composition and asset prices using: (i) a linear framework based on a fully simultaneous system approach in a Bayesian environment; and (ii) a nonlinear specification that relies on a smooth transition regression model.     

Unilateral production restrictions in a dynamic duopoly

This paper examines a dynamic game of exploitation of a productive asset by a duopoly. A closed-loop Nash equilibrium of the game is constructed and used to analyze the effects of a unilateral production restriction. Surprisingly, such unilateral action may result in a decrease of the long-run asset's stock. We also exhibit production restrictions that can result simultaneously in an increase of the asset's stock and the long-run profits of the firm that is being imposed the production restriction. Moreover, a unilateral decrease of the production of one firm can induce its rival to also decrease its production.     

When sunspots don't matter

Summary We show that a finite, competitive economy isimmune to sunspots if (i) preferences are strictly convex, (ii) the set of feasible allocations is convex, and (iii) the contingent-claims market is perfect. The conditions (i)–(ii) cover some, but not all, economies with nonconvex technologies. Based on an indivisible-good example, we show that even economies with strictly convex preferences and full insurance arenot in general immune from sunspots. We also show that (1) the sufficient conditions (i)–(iii) are not necessary for sunspot immunity and (2)ex-ante efficiency is not necessary for immunity from sunspots.This paper is based on an earlier paper, Indivisibilities in Production, and Sunspot Equilibrium, presented at the 1990 S.E.D.C. Meetings, Minneapolis-St. Paul, June 1990. The research support of NSF Grant SES-9012780, the Center for Analytic Economics, and the Thorne Fund is gratefully acknowledged.     

“Overreaction” of Asset Prices in General Equilibrium

We attempt to explain the overreaction of asset prices to movements in short-term interest rates, dividends, and asset supplies. The key element of our explanation is a margin constraint that traders face which limits their leverage to a fraction of the value of their assets. Traders may lever themselves, furthermore, either directly by borrowing short term or indirectly by engaging in futures and options trading, so that the scenario is relevant to contemporary financial markets. When some shock pushes asset prices to a low enough level at which the margin constraint binds, traders are forced to liquidate assets. This drives asset prices below what they would be with frictionless markets. Also, a shock which simply increases the likelihood that the margin constraint will bind can have a very similar effect on asset prices. We construct a general equilibrium model with margin constrained traders and derive some qualitative properties of asset prices. We present an analytical solution for a deterministic version of the model and a simple numerical computation of the stochastic version.Journal of Economic LiteratureClassification Numbers: G1, E0.     

Conditional volatility and correlations of weekly returns and the VaR analysis of 2008 stock market crash

Modelling of conditional volatilities and correlations across asset returns is an integral part of portfolio decision making and risk management. Over the past three decades there has been a trend towards increased asset return correlations across markets, a trend which has been accentuated during the recent financial crisis. We shall examine the nature of asset return correlations using weekly returns on futures markets and investigate the extent to which multivariate volatility models proposed in the literature can be used to formally characterize and quantify market risk. In particular, we ask how adequate these models are for modelling market risk at times of financial crisis. In doing so we consider a multivariate t version of the Gaussian dynamic conditional correlation (DCC) model proposed by Engle (2002), and show that the t-DCC model passes the usual diagnostic tests based on probability integral transforms, but fails the value at risk (VaR) based diagnostics when applied to the post 2007 period that includes the recent financial crisis.     

The Power of the Euro–Sterling Rates in Explaining Asset Market Rates: A High‐frequency Analysis

This article makes use of high‐frequency asset market data to explain unexpected changes in interest rates using the methodology proposed by Cochrane and Piazzesi (2002) . This work departs from the existing literature because it uses UK market expectations to capture unexpected movements in the base rate, and explores its effect on a large number of asset market variables. Results indicate that the relation between asset market data and unexpected base rate changes is stronger and more consistent than the relation between asset market data and raw base rate changes. Results appear to be robust to extreme value changes.     

Balance sheet identity and Walras' Law

The balance sheet identity is interpreted to imply that if n ? 1 of n assets are in stock equilibrium, so is the remaining asset. Under the notion of the end-of-period equilibrium, the following are shown. (1) This interpretation leads to the contradiction that the system does not allow enough independent equilibrium relations to determine uniquely the equilibrium values of its endogenous variables. (2) The balance sheet identity is equivalent to Walras' Law in flow form. Thus, Foley's methodological precept is verified; transforming a period model into its continuous time analogue does not lead to different outcomes from period analysis.     

Arbitrage and equilibrium with portfolio constraints

We consider a multiperiod financial exchange economy with nominal assets and restricted participation, where each agent’s portfolio choice is restricted to a closed, convex set containing zero, as in Siconolfi (Non-linear Dynamics in Economics and Social Sciences, 1989). Using an approach that dates back to Cass (CARESS Working Paper, 1984; J Math Econ 42:384–405, 2006) in the unconstrained case, we seek to isolate arbitrage-free asset prices that are also quasi-equilibrium or equilibrium asset prices. In the presence of such portfolio restrictions, we need to confine our attention to aggregate arbitrage-free asset prices, i.e., for which there is no arbitrage in the space of marketed portfolios. Our main result states that such asset prices are quasi-equilibrium prices under standard assumptions and then deduces that they are equilibrium prices under a suitable condition on the accessibility of payoffs by agents, i.e., every payoff that is attainable in the aggregate can be marketed through some agent’s portfolio set. This latter result extends previous work by Martins-da-Rocha and Triki (Working Paper, University of Paris 1, 2005).     

Multinational involvement and risk

This study reveals that foreign sales, profit and asset percentage data all relate to the same underlying multinational involvement phenomena, and finds no inverse relation between two common measures of risk and multinational involvement. These results suggest the multinational phenomena must be rationalized on the basis of imperfections in input and output markets, rather than on the basis of imperfections in international capital markets.     

Author index for volume 32

A way of establishing the stationary Pareto optimality of asset equilibria in stochastic settings with age diversity among the agents is suggested. Difficulties in obtaining such results arise because agents' behavior is affected by random future state variables while Pareto optimality, defined in terms of expected lifetime utility of representative agents conditioned on their first period state, involves redistributions of consumption among agents with different histories of realized states. Frobenius' theorem is used to establish the existence of weights for which the so-weighted sum of representative agents' (conditional) expected utilities is maximized at the asset equilibrium allocation.     

A new ICEEMDAN-based transfer entropy quantifying information flow between real estate and policy uncertainty

We quantify the dependence between real estate indices and global economic policy uncertainty for 12 top-advanced countries. Generally, real estate investments are found to be highly risky to information flow from global economic policy uncertainty. amidst policy uncertainty, we find diversification, safe haven, and hedging prospects – based on the market conditions – at short term frequencies only, for the pairs between (a) Japan and the US; (b) Singapore and the US; (c) China and Canada; (d) China and Hong Kong. Our findings underscore market efficiency (inefficiency) at mid-and long-term (short-term) frequencies. In the presence of policy uncertainty, our findings underscore the operability of ingrained market dynamics between real estate investments in the mid-and long-term horizons. It is prudent for investors to combine real estate investments with other asset classes that are less risky to (or are positive recipients of) information flow from global EPU to hedge against adverse market shocks from any asset in the portfolio based on market conditions. Practically, not only should legislations be flexible to the changing market trends in the short term, but they should also be strategically crafted to retain the fundamental market dynamics between real estate investments in the mid-and long-term economic horizons.     

Does Intrinsic Habit Formation Actually Resolve the Equity Premium Puzzle?

G. M. Constantinides (1990, Journal of Political Economy98, 519–543) describes a simple model of intrinsic habit formation that appears to resolve the “equity premium puzzle” of R. Mehra and E. C. Prescott (1985, Journal of Monetary Economics15, 145–161). This finding is particularly important, since it has motivated a broader consideration of the implications of habit formation preferences in dynamic equilibrium models. However, consumption growth actually behaves very differently pre- and post-1948, and the explanatory power of the habit formation model is driven by the pre-1948 data. Using data from 1949 to 2000, constructed in a manner comparable to R. Mehra and E. C. Prescott, I demonstrate that intrinsic habit cannot rationalize the unconditional moments of discrete consumption and real asset returns with values of the risk aversion coefficient that are less than four times larger than the values found by G. M. Constantinides for any feasible calibration of the model. Journal of Economic Literature Classification Numbers: E21, G12.