Optimal risk sharing and borrowing constraints in a continuous-time model with limited commitment

We study a continuous-time version of the optimal risk-sharing problem with one-sided commitment. In the optimal contract, the agent?s consumption is a time-invariant, strictly increasing function of a single state variable: the maximal level of the agent?s income realized to date. We characterize this function in terms of the agent?s outside option value function and the discounted amount of time in which the agent?s income process is expected to reach a new to-date maximum. Under constant relative risk aversion we solve the model in closed-form: optimal consumption of the agent equals a constant fraction of his maximal income realized to date. In the complete-markets implementation of the optimal contract, the Alvarez–Jermann solvency constraints take the form of a simple borrowing constraint familiar from the Bewley–Aiyagari incomplete-markets models.     

EMS exchange rate expectations and time-varying risk premia

In this paper we examine exchange risk premia employing a survey dataset of EMS exchange rates. We are able to test a risk premium model directly, i.e. without having to rely on the rational expectations assumption. Our results indicate that time-varying risk premia are present in almost all cases and that a GARCH-in-mean specification for the premium is often appropriate.     

Diverse beliefs and time variability of risk premia

Why do risk premia vary over time? We examine this problem theoretically and empirically by studying the effect of market belief on risk premia. Individual belief is taken as a fundamental primitive state variable. Market belief is observable; it is central to the empirical evaluation and we show how to measure it. Our asset pricing model is familiar from the noisy REE literature but we adapt it to an economy with diverse beliefs. We derive equilibrium asset prices and implied risk premium. Our approach permits a closed form solution of prices; hence we trace the exact effect of market belief on the time variability of asset prices and risk premia. We test empirically the theoretical conclusions. Our main result is that, above the effect of business cycles on risk premia, fluctuations in market belief have significant independent effect on the time variability of risk premia. We study the premia on long positions in Federal Funds Futures, 3- and 6-month Treasury Bills (T-Bills). The annual mean risk premium on holding such assets for 1?C12?months is about 40?C60 basis points and we find that, on average, the component of market belief in the risk premium exceeds 50% of the mean. Since time variability of market belief is large, this component frequently exceeds 50% of the mean premium. This component is larger the shorter is the holding period of an asset and it dominates the premium for very short holding returns of less than 2?months. As to the structure of the premium we show that when the market holds abnormally favorable belief about the future payoff of an asset the market views the long position as less risky hence the risk premium on that asset declines. More generally, periods of market optimism (i.e. ??bull?? markets) are shown to be periods when the market risk premium is low while in periods of pessimism (i.e. ??bear?? markets) the market??s risk premium is high. Fluctuations in risk premia are thus inversely related to the degree of market optimism about future prospects of asset payoffs. This effect is strong and economically very significant.     

Money and credit with limited commitment and theft

We study the interplay among imperfect memory, limited commitment, and theft, in an environment that can support monetary exchange and credit. Imperfect memory makes money useful, but it also permits theft to go undetected, and therefore provides lucrative opportunities for thieves. Limited commitment constrains credit arrangements, and the constraints tend to tighten with imperfect memory, as this mitigates punishment for bad behavior in the credit market. Theft matters for optimal monetary policy, but at the optimum theft will not be observed in the model. The Friedman rule is in general not optimal with theft, and the optimal money growth rate tends to rise as the cost of theft falls.     

Fiber investment and access under uncertainty: long-term contracts,risk premia,and access options

Journal of Regulatory Economics - Regulated access schemes shape incentives for both investment and entry in next-generation networks. We study in a general duopoly setting whether and how risk...     

Financial amplification of foreign exchange risk premia

Theories of financial frictions in international capital markets suggest that financial intermediaries' balance sheet constraints amplify fundamental shocks. We present empirical evidence for such theories by decomposing the U.S. dollar risk premium into components associated with macroeconomic fundamentals, and a component associated with financial intermediary balance sheets. Relative to the benchmark model with only macroeconomic state variables, balance sheets amplify the U.S. dollar risk premium. We discuss applications to financial stability monitoring.     

Foreign currency debt, risk premia and macroeconomic volatility

This paper studies the relationships between foreign currency debt, macroeconomic volatility, and risk premia in a model of a small open emerging market economy. The external value of the local currency is counter-cyclical, so that foreign currency debt requires larger repayments than local currency debt in bad states of nature. The level of foreign currency-denominated debts, therefore, affects the volatility of aggregate demand and by extension of the exchange rate. Exchange rate volatility is in turn an important determinant of the risk premium on local currency debt. Finally, this risk premium is a major factor in the choice of local versus foreign currency for emerging market borrowers. The mutual endogeneity of foreign currency debt, risk premia, and macroeconomic volatility creates important feedback effects in the economy: small increases in international risk aversion may entail large amplification effects on macroeconomic volatility since domestic borrowers substitute towards cheaper but riskier foreign currency debt finance.     

Bond risk premia, macroeconomic fundamentals and the exchange rate

We propose a two-country no-arbitrage term-structure model to analyze the joint dynamics of bond yields, macroeconomic variables and the exchange rate. The model allows to understand how exogenous shocks to the exchange rate affect the yield curves, how bond yields co-move in different countries and how the exchange rate is influenced by interest rates, macro-economic variables and time-varying bond risk premia.Estimating the model with US and German data, we find that time-varying bond risk premia account for a significant portion of the variability of the exchange rate: apparently, a currency tends to appreciate when investors expect large capital gains on long-term bonds denominated in that currency. A number of other novel empirical findings emerge.     

The role of sentiment in global risk premia

This article examines the role of sentiment for global risk premia. We analyse whether the global risk premia on macroeconomic fundamentals can be estimated more thoroughly if sentiment is included as additional conditioning information. The analysis is performed in the framework of a conditional multiple beta pricing model. The focus of analysis is the asset excess returns of the G-7 stock markets in the period from February 1999 to February 2012. The obtained results indicate that sentiment as conditioning information is able to contribute to the explanation of the general macroeconomic risk premia.     

Imperfect credibility and risk premia in the European Monetary System

The paper deals with the estiamation of models for the expected rate of depreciation within the currency bands of the French franc and the Italian lira against the deutshmark, both unconditional and conditional upon no realignment, as well as the estimastion of models for risk premia. Using these estimates,estimates are constructed for the expected rate of depreciation, the expected rate of realignment and the expected rate of devaluation of these exchange rates during their EMS period by appropriate adjustment of interest rate differentials. It is found that these adjustments are of non-trivial magnitude.     

Bond risk premia,macroeconomic fundamentals and the exchange rate

We propose a two-country no-arbitrage term-structure model to analyze the joint dynamics of bond yields, macroeconomic variables and the exchange rate. The model allows to understand how exogenous shocks to the exchange rate affect the yield curves, how bond yields co-move in different countries and how the exchange rate is influenced by interest rates, macro-economic variables and time-varying bond risk premia.Estimating the model with US and German data, we find that time-varying bond risk premia account for a significant portion of the variability of the exchange rate: apparently, a currency tends to appreciate when investors expect large capital gains on long-term bonds denominated in that currency. A number of other novel empirical findings emerge.     

Strategy-proof risk sharing

We consider risk sharing problems with a single good and a finite number of states. Agents have a common prior and their preferences are represented in the expected utility form and are risk averse. We study efficient and individually rational risk sharing rules satisfying strategy-proofness, the requirement that no one can ever benefit by misrepresenting his preference. When aggregate certainty holds, we show that “fixed price selections” from Walrasian correspondence are the only rules satisfying efficiency, individual rationality, and strategy-proofness. However, when aggregate uncertainty holds, we show that there exists no rule satisfying the three requirements. Moreover, in the two agents case, we show that dictatorial rules are the only efficient and strategy-proof rules. Dropping the common prior assumption in the model, we show that this assumption is necessary and sufficient for the existence of rules satisfying the three main requirements in the two agents and aggregate certainty case.     

Competition, human capital and income inequality with limited commitment

We develop a dynamic model with two-sided limited commitment to study how barriers to competition, such as restrictions to business start-up and non-competitive covenants, affect the incentive to accumulate human capital. When contracts are not enforceable, high barriers lower the outside value of ‘skilled workers’ and reduce the incentive to accumulate human capital. In contrast, low barriers can result in over-accumulation of human capital. This can be socially optimal if there are positive spillovers. A calibration exercise shows that this mechanism can account for a sizable portion of cross-country income inequality.     

Optimal risk‐sharing under adverse selection and imperfect risk perception

Abstract.  The present paper thoroughly explores second‐best efficient allocations in an insurance economy with adverse selection. We start with a natural extension of the classical model, assuming less than perfect risk perception. We characterize the constraints on efficient redistribution, and we summarize the incidence of incentives on the economy with the notions of weak and strong adverse selection. Finally, we show in what sense improving risk perception enhances welfare.     

Efficiency and sharing of investment in specific human capital under risk aversion

This paper analyses the investment behavior of a risk-averse worker who searches for other jobs in a two-period model. It will be shown that given an appropriate investment technology, the worker will invest in specific human capital efficiently if his investment costs and return can be shared with some parties. The presence of sharing allows the worker to invest efficiently without being affected by his risk aversion since he can adjust his share of the investment in a way compatible with his attitude towards risk.     

Social security and risk sharing

In this paper we identify conditions under which the introduction of a pay-as-you-go social security system is ex ante Pareto-improving in a stochastic OLG economy with capital accumulation and land. We argue that these conditions are consistent with realistic specifications of the parameters of the economy. In our model financial markets are complete and competitive equilibria interim Pareto efficient. Therefore, a welfare improvement can only be obtained if agents? welfare is evaluated ex ante, and arises from an improvement in intergenerational risk sharing. We also examine the optimal size of a given social security system as well as its optimal reform.     

Trade integration and risk sharing

What are the effects of increased trade in goods and services on the trade balance? We study the effects of reducing transport costs in a Ricardian model with complete asset markets and find that this increases the volatility of the trade balance. This result applies regardless of whether supply or demand shocks are the main source of economic fluctuations. Both type of shocks generate fluctuations in the trade balance that are in part moderated by stabilizing movements in the terms of trade. Trade integration dampens these terms of trade movements and, for a given distribution of shocks, amplifies fluctuations in the trade balance. To overturn this result, one must assume that either trade integration is sufficiently biased towards goods with strong comparative advantage and/or risk aversion is sufficiently extreme. We calibrate the model to U.S. data and find that, for reasonable parameter values, increased trade in services could double the volatility of the trade balance.     

Sovereign default risk premia,fiscal limits,and fiscal policy

We develop a closed economy model to study the interactions among sovereign risk premia, fiscal limits, and fiscal policy. The fiscal limits, which measure the government's ability to service its debt, arise endogenously from dynamic Laffer curves. The state-dependent distributions of fiscal limits depend on the growth of lump-sum transfers, the size of the government, the degree of countercyclical policy responses, and economic diversity. The country-specific fiscal limits imply that the market perceives the riskiness of sovereign debt issued by different countries to be different, which is consistent with the observation that developed countries are downgraded at different levels of debt. A nonlinear relationship between sovereign risk premia and the level of government debt emerges in equilibrium, which is in line with the empirical evidence that once risk premia begin to rise, they do so rapidly. Nonlinear simulations show that fiscal austerity measures that aim to balance the government budget in the short run fail to contain the default risk premium, even with sizeable cuts in government purchases; but a long-term plan for fiscal reform, if it credibly changes the market's expectation about future fiscal policies, can alleviate the rising risk premium.     

Optimal risk sharing with background risk

This paper examines qualitative properties of efficient insurance contracts in the presence of background risk. In order to get results for all strictly risk-averse expected utility maximizers, the concept of “stochastic increasingness” is used. Different assumptions on the stochastic dependence between the insurable and uninsurable risk lead to different qualitative properties of the efficient contracts. The new results obtained under hypotheses of dependent risks are compared to classical results in the absence of background risk or to the case of independent risks. The theory is further generalized to nonexpected utility maximizers.     

Political intergenerational risk sharing

In a stochastic two-period OLG model, featuring an aggregate shock to the economy, ex-ante optimality requires intergenerational risk sharing. We compare the level of intergenerational risk sharing chosen by a benevolent government and by an office-seeking politician. In our political system, the transfer of resources across generations is determined as a Markov equilibrium of a probabilistic voting game. Low realized returns on the risky asset induce politicians to compensate the old through a PAYG system. This political system typically generates an intergenerational risk sharing scheme that is (i) larger, (ii) more persistent, and (iii) less responsive to the realization of the shock than the social optimum. This is because the current politician anticipates her transfers to the elderly to be compensated by future politicians through offsetting transfers, and hence overspends.