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.Efficient contracts; Stochastically increasing; Incomplete markets; Insurance;

Robust Optimal Risk Sharing and Risk Premia in Expanding Pools

We consider the problem of optimal risk sharing in a pool of cooperative agents. We analyze the asymptotic behavior of the certainty equivalents and risk premia associated with the Pareto optimal risk sharing contract as the pool expands. We first study this problem under expected utility preferences with an objectively or subjectively given probabilistic model. Next, we develop a robust approach by explicitly taking uncertainty about the probabilistic model (ambiguity) into account. The resulting robust certainty equivalents and risk premia compound risk and ambiguity aversion. We provide explicit results on their limits and rates of convergence, induced by Pareto optimal risk sharing in expanding pools

Optimal intergenerational risk sharing

This paper studies optimal intergenerational transfer policy under stochastic labor income and capital returns. It has implications for Social Security, government tax and debt policy, and DB pension funds. A stylized two-period overlapping-generations model is developed where a central planner implements pay-as-you-go transfers. I allow for autocorrelation in the labor income and skewness in the capital return and calibrate the model parameters to US data. I show that state-contingent transfers facilitate intergenerational risk sharing in a way that is similar to portfolio insurance using put options. That is, the working generation provides downside risk insurance to the old on their savings. In addition, when no riskfree asset is available, these transfers improve utility by substituting for this missing asset. I further find that imposing an incentive constraint for the working generation has little impact when transfers also have this substitution role, but it causes the transfer scheme to collapse to the zero-transfer scheme when a risk free asset is available

Exclusivity as Inefficient Insurance

It is well established that an incumbent firm may use exclusivity contracts so as to monopolize an industry or deter entry. Such an anticompetitive practice could be tolerated if it were associated with sufficiently large efficiency gains, e.g. insuring buyers against price volatility. In this paper we study the trade-off between positive effects (risk sharing) and negative effects (exclusion) of exclusivity contracts. We revisit the seminal model of Aghion and Bolton (1987) under risk-aversion and show that although exclusivity contracts induce optimal risk-sharing, they can be used not only to deter the entry of a more efficient rival on the product market but also to crowd out financial investors willing to insure the buyer at competitive rates. We further show that in a world without financial investors, purely financial bilateral instruments, such as forward contracts, achieve optimal risk sharing without distorting product market outcomes. Thus, there is no room for an insurance defense of exclusivity contracts.exclusivity;contracts;monopolization;risk-aversion;risk-sharing;damages

Risk-sharing or risk-taking? Counterparty risk, incentives and margins

We analyze optimal hedging contracts and show that although hedging aims at sharing risk, it can lead to more risk-taking. News implying that a hedge is likely to be loss-making undermines the risk-prevention incentives of the protection seller. This incentive problem limits the capacity to share risks and generates endogenous counterparty risk. Optimal hedging can therefore lead to contagion from news about insured risks to the balance sheet of insurers. Such endogenous risk is more likely to materialize ex post when the ex ante probability of counterparty default is low. Variation margins emerge as an optimal mechanism to enhance risk-sharing capacity. Paradoxically, they can also induce more risk-taking. Initial margins address the market failure caused by unregulated trading of hedging contracts among protection sellers. JEL Classification: G21, G22, D82.Insurance, moral hazard, counterparty risk, margin requirements, derivatives.

The role of financial market structure and the trade elasticity for monetary policy in open economies

The degree of international risk sharing matters for how monetary policy should optimally be conducted in an open economy. This is because risk sharing affects the way in which monetary policy is affected by terms of trade considerations. In a standard two-country model with monopolistic competition and nominal rigidities I consider different assumptions on international financial markets – complete markets, financial autarky and a bond economy – and a large region for the crucial parameter of the trade elasticity. There are three main results: one, the prescription of (producer) price stability as the optimal policy is obtained only as a special case, while in general it is optimal to deviate from a strictly zero inflation rate. Two, while gains from international policy coordination are generally small, they become potentially substantial when international risk sharing is poor and wealth effects from shocks across countries are large. And, three, when international financial markets are incomplete, there are also (sometimes considerable) gains over the flexible price allocation achievable.monetary policy, risk sharing, price stability, policy coordination, financial market structure, trade elasticity

Optimal Taxation and Risk-Sharing Arrangements in an Economic Federation

This paper analyzes optimal taxation and risk-sharing arrangements in an economy with two levels of government. Both levels provide public goods and finance their expenditures via labor income taxation, where the tax base is responsive to the private agents' labor supply decisions. The localities are assumed to experience different random productivity shocks, meaning hat the private labor supply decisions as well as the choices of income tax rates are carried out under uncertainty. Part of the central overnment's decision problem is then to provide ax revenue sharing between the local governments. The optimal degree of revenue sharing depends on whether or not the localities/regions differ with respect to labor supply incentives.Optimal taxation; multilevel government; fiscal externalities; uncertainty; risk-sharing

Financial globalization and monetary policy

Recent data show substantial increases in the size of gross external asset and liability positions. The implications of these developments for optimal conduct of monetary policy are analyzed in a standard open economy model which is augmented to allow for endogenous portfolio choice. The model shows that monetary policy takes on new importance due to its impact on nominal asset returns. Nevertheless, the case for price stability as an optimal monetary rule remains. In fact, it is reinforced. Even without nominal price rigidities, price stability is optimal because it enhances the risk sharing properties of nominal bonds. --Portfolio Choice,International Risk Sharing,Exchange Rate