Large economies with differential information but without free disposal

We consider exchange economies with a continuum of agents and differential information about finitely many states of nature. It was proved in Einy, Moreno and Shitovitz (2001) that if we allow for free disposal in the market clearing (feasibility) constraints then an irreducible economy has a competitive (or Walrasian expectations) equilibrium, and moreover, the set of competitive equilibrium allocations coincides with the private core. However when feasibility is defined with free disposal, competitive equilibrium allocations may not be incentive compatible and contracts may not be enforceable (see e.g. Glycopantis, Muir and Yannelis (2002)). This is the main motivation for considering equilibrium solutions with exact feasibility. We first prove that the results in Einy et al. (2001) are still valid without freedisposal. Then we define an incentive compatibility property motivated by the issue of contracts’ execution and we prove that every Pareto optimal exact feasible allocation is incentive compatible, implying that contracts of competitive or core allocations are enforceable.

An ordering of measures of the welfare cost of inflation in economies with interest-bearing deposits

This paper builds on Lucas (2000) and on Cysne (2003) to derive and order six alternative measures of the welfare costs of inflation (five of which already existing in the literature) for any vector of opportunity costs. The ordering of the functions is carried out for economies with or without interestbearing deposits. We provide examples and closed-form solutions for the log-log money demand both in the unidimensional and in the multidimensional setting (when interest-bearing monies are present). An estimate of the maximum relative error a researcher can incur when using any particular measure is also provided.

Monetary arrangements for emerging economies

In this paper we look at various alternatives for monetary regimes: dollarization, monetary union and local currency. We use an extension of the debt crisis model of Cole and Kehoe ([3], [4] and [5]), although we do not necessarily follow their sunspot interpretation. Our focus is to appraise the welfare of a country which is heavily dependent on international capital due to low savings, for example, and might suffer a speculative attack on its external public debt. We study the conditions under which countries will be better off adopting each one of the regimes described above. If it belongs to a monetary union or to a local currency regime, a default may be avoided by an ination tax on debt denominated in common or local currency, respectively. Under the former regime, the decision to inate depends on each member country's political inuence over the union's central bank, while, in the latter one, the country has full autonomy to decide about its monetary policy. The possibility that the government inuences the central bank to create ination tax for political reasons adversely affects the expected welfare of both regimes. Under dollarization, ination is ruled out and the country that is subject to an external debt crisis has no other option than to default. Accordingly, one of our main results is that shared ination control strengthens currencies and a common-currency regime is superior in terms of expected welfare to the local-currency one and to dollarization if external shocks that member countries suffer are strongly correlated to each other. On the other hand, dollarization is dominant if the room for political ination under the alternative regime is high. Finally, local currency is dominant if external shocks are uncorrelated and the room for political pressure is mild. We nish by comparing Brazil's and Argentina's recent experiences which resemble the dollarization and the local currency regimes, and appraising the incentives that member countries would have to unify their currencies in the following common markets: Southern Common Market, Andean Community of Nations and Central American Common Market.

Unbounded exchange economies with satiation: how far can we go?

We unify and generalize the existence results in Werner (1987), Dana, Le Van and Magnien (1999), Allouch, Le Van and Page (2006) and Allouch and Le Van (2008). We also show that, in terms of weakening the set of assumptions, we cannot go too far.

Contract enforcement and incentive compatibility in large economies with differential information: the role of exact feasibility

We consider exchange economies with a continuum of agents and differential information about finitely many states of nature. It was proved in Einy, Moreno and Shitovitz (2001) that if we allow for free disposal in the market clearing (feasibility) constraints then an irreducible economy has a competitive (or Walrasian expectations) equilibrium, and moreover, the set of competitive equilibrium allocations coincides with the private core. However when feasibility is defined with free disposal, competitive equilibrium allocations may not be incentive compatible and contracts may not be enforceable (see e.g. Glycopantis, Muir and Yannelis (2002)). This is the main motivation for considering equilibrium solutions with exact feasibility. We first prove that the results in Einy et al. (2001) are still valid without free-disposal. Then we define an incentive compatibility property motivated by the issue of contracts’ execution and we prove that every Pareto optimal exact feasible allocation is incentive compatible, implying that contracts of a competitive or core allocations are enforceable.

Simple calvo economies with heterogeneous pricing

A motivação para este trabalho vem dos principais resultados de Carvalho e Schwartzman (2008), onde a heterogeneidade surge a partir de diferentes regras de ajuste de preço entre os setores. Os momentos setoriais da duração da rigidez nominal são su cientes para explicar certos efeitos monetários. Uma vez que concordamos que a heterogeneidade é relevante para o estudo da rigidez de preços, como poderíamos escrever um modelo com o menor número possível de setores, embora com um mínimo de heterogeneidade su ciente para produzir qualquer impacto monetário desejado, ou ainda, qualquer três momentos da duração? Para responder a esta questão, este artigo se restringe a estudar modelos com hazard-constante e considera que o efeito acumulado e a dinâmica de curto-prazo da política monetária são boas formas de se resumir grandes economias heterogêneas. Mostramos que dois setores são su cientes para resumir os efeitos acumulados de choques monetários, e economias com 3 setores são boas aproximações para a dinâmica destes efeitos. Exercícios numéricos para a dinâmica de curto prazo de uma economia com rigidez de informação mostram que aproximar 500 setores usando apenas 3 produz erros inferiores a 3%. Ou seja, se um choque monetário reduz o produto em 5%, a economia aproximada produzirá um impacto entre 4,85% e 5,15%. O mesmo vale para a dinâmica produzida por choques de nível de moeda em uma economia com rigidez de preços. Para choques na taxa de crescimento da moeda, a erro máximo por conta da aproximação é de 2,4%.

A estrutura de regulação dos mercados futuros no Brasil e o uso de modelos estatísticos de precificação na atividade de supervisão dos órgãos reguladores

Esta dissertação procurou identificar as diretrizes de supervisão dos mercados futuros no Brasil frente às práticas de regulação utilizadas em outros países do mundo, basicamente aqueles cujas economias e mercados são maiores do que o brasileiro, em volume de contratos negociados. O desenvolvimento do tema se deu de maneira a estimular o uso de tais práticas na estrutura local de supervisão, com vistas a uma melhoria da atividade dos órgãos reguladores e ao crescimento do mercado de capitais brasileiro. Dentre as referidas práticas, destacou-se a utilização de modelos estatísticos de precificação dos contratos negociados no sentido de balizar a atuação dos departamentos de fiscalização na investigação de condições artificiais de mercado. A abordagem desses modelos abrangeu desde a definição de conceitos fundamentais até a apresentação de um estudo de caso com opções sobre ações, passando pela caracterização dos principais modelos e formas de calcular a volatilidade no preço desses títulos. Os resultados de pesquisa foram relacionados às origens legais e ao desenvolvimento econômico recente do Brasil, que levaram à sofisticação dos mecanismos de financiamento do mercado de capitais nacional, não se limitando ao simples apontamento dos pontos fracos da estrutura local de supervisão. Finalmente, a pesquisa evoluiu para as necessidades práticas da atividade de supervisão a serem atendidas pelo regulador, segundo as características operacionais dos principais mercados, a fim de que a bolsa de futuros brasileira reforce sua posição competitiva no cenário mundial.

A estrutura de regulação dos mercados futuros no Brasil e o uso de modelos estatísticos de precificação, na atividade de supervisão dos órgãos reguladores.

Esta dissertação procurou identificar as diretrizes de supervisão dos mercados futuros no Brasil frente às práticas de regulação utilizadas em outros países do mundo, basicamente aqueles cujas economias e mercados são maiores do que o brasileiro, em volume de contratos negociados. O desenvolvimento do tema se deu de maneira a estimular o uso de tais práticas na estrutura local de supervisão, com vistas a uma melhoria da atividade dos órgãos reguladores e ao crescimento do mercado de capitais brasileiro. Dentre as referidas práticas, destacou-se a utilização de modelos estatísticos de precificação dos contratos negociados no sentido de balizar a atuação dos departamentos de fiscalização na investigação de condições artificiais de mercado. A abordagem desses modelos abrangeu desde a definição de conceitos fundamentais até a apresentação de um estudo de caso com opções sobre ações, passando pela caracterização dos principais modelos e formas de calcular a volatilidade no preço desses títulos. Os resultados de pesquisa foram relacionados às origens legais e ao desenvolvimento econômico recente do Brasil, que levaram à sofisticação dos mecanismos de financiamento do mercado de capitais nacional, não se limitando ao simples apontamento dos pontos fracos da estrutura local de supervisão. Finalmente, a pesquisa evoluiu para as necessidades práticas da atividade de supervisão a serem atendidas pelo regulador, segundo as características operacionais dos principais mercados, a fim de que a bolsa de futuros brasileira reforce sua posição competitiva no cenário mundial.

Competitive equilibria in infinite-horizon collateralized economies with default penalties

Araújo, Páscoa and Torres-Martinez (2002) have shown that, without imposing either debt constraints or transversality conditions, Ponzi schemes are ruled out in infinite horizon economies with default when collateral is the only mechanism that partially secures loans. Páscoa and Seghir (2008) subsequently show that Ponzi schemes may reappear if, additionally to the seizure of the collateral, there are sufficiently harsh default penalties assessed (directly in terms of utility) against the defaulters. They also claim that if default penalties are moderate then Ponzi schemes are ruled out and existence of a competitive equilibrium is ensured. The objective of this paper is two fold. First, contrary to what is claimed by Páscoa and Seghir (2008), we show that moderate default penalties do not always prevent agents to run a Ponzi scheme. Second, we provide an alternative condition on default penalties that is sufficient to rule out Ponzi schemes and ensure the existence of a competitive equilibrium.

On Ponzi schemes in infinite horizon collateralized economies with default penalties

Araujo, Páscoa and Torres-Martínez (2002) showed that, without imposing any debt constraint, Ponzi schemes are ruled out in infinite horizon economies with limited commitment when collateral is the only mechanism that partially secures loans. Páscoa and Seghir (2009) presented two examples in which they argued that Ponzi schemes may reappear if, additionally to the seizure of the collateral, there are sufficiently harsh default penalties assessed (directly in terms of utility) against the defaulters. Moreover, they claimed that if default penalties are moderate then Ponzi schemes are ruled out and existence of a competitive equilibrium is restored. This paper questions the validity of the claims made in Páscoa and Seghir (2009). First, we show that it is not true that harsh default penalties lead to Ponzi schemes in the examples they have proposed. A competitive equilibrium with no trade can be supported due to unduly pessimistic expectations on asset deliveries. We subsequently refine the equilibrium concept in the spirit of Dubey, Geanakoplos and Shubik (2005) in order to rule out spurious inactivity on asset markets due to irrational expectations. Our second contribution is to provide a specific example of an economy with moderate default penalties in which Ponzi schemes reappear when overpessimistic beliefs on asset deliveries are ruled out. Our finding shows that, contrary to what is claimed by Páscoa and Seghir (2009), moderate default penalties do not always prevent agents to run a Ponzi scheme.

Endogenous debt constraints in collateralized economies with default penalties

In infinite horizon financial markets economies, competitive equilibria fail to exist if one does not impose restrictions on agents' trades that rule out Ponzi schemes. When there is limited commitment and collateral repossession is the unique default punishment, Araujo, Páscoa and Torres-Martínez (2002) proved that Ponzi schemes are ruled out without imposing any exogenous/endogenous debt constraints on agents' trades. Recently Páscoa and Seghir (2009) have shown that this positive result is not robust to the presence of additional default punishments. They provide several examples showing that, in the absence of debt constraints, harsh default penalties may induce agents to run Ponzi schemes that jeopardize equilibrium existence. The objective of this paper is to close a theoretical gap in the literature by identifying endogenous borrowing constraints that rule out Ponzi schemes and ensure existence of equilibria in a model with limited commitment and (possible) default. We appropriately modify the definition of finitely effective debt constraints, introduced by Levine and Zame (1996) (see also Levine and Zame (2002)), to encompass models with limited commitment, default penalties and collateral. Along this line, we introduce in the setting of Araujo, Páscoa and Torres-Martínez (2002), Kubler and Schmedders (2003) and Páscoa and Seghir (2009) the concept of actions with finite equivalent payoffs. We show that, independently of the level of default penalties, restricting plans to have finite equivalent payoffs rules out Ponzi schemes and guarantees the existence of an equilibrium that is compatible with the minimal ability to borrow and lend that we expect in our model. An interesting feature of our debt constraints is that they give rise to budget sets that coincide with the standard budget sets of economies having a collateral structure but no penalties (as defined in Araujo, Páscoa and Torres-Martínez (2002)). This illustrates the hidden relation between finitely effective debt constraints and collateral requirements.

Media piracy in emerging economies

Media Piracy in Emerging Economies is the first independent, large-scale study of music, film and software piracy in the developing world, with a focus on Brazil, India, Russia, South Africa, Mexico and Bolivia. Based on three years of work by some thirty-five researchers, the study tells two overarching stories: one tracing the explosive growth of piracy as digital technologies became cheap and ubiquitous around the world, and another following the growth of industry lobbies that have reshaped laws and law enforcement around copyright protection. The report argues that enforcement efforts have largely failed, and that the problem of piracy is better addressed as a failure of affordable access to media in legal markets.

US real interest rates and default risk in emerging economies

This paper empirically investigates the impact of changes in US real interest rates on sovereign default risk in emerging economies using the method of identification through heteroskedasticity. Policy-induced increases in US interest rates starkly raise default risk in emerging market economies. However, the overall correlation between US real interest rates and the risk of default is negative, demonstrating that the effects of other variables dominate the anterior relationship

DSGE model with banking sector for emerging economies : estimated using Bayesian methodology for Brazil

Economias emergentes sofrem importantes restrições de crédito quando comparadas com economias desenvolvidas, entretanto, modelos estocásticos de equilíbrio geral (DSGE) desenhados para economias emergentes ainda precisam avançar nessa discussão. Nós propomos um modelo DSGE que pretende representar uma economia emergente com setor bancário baseado em Gerali et al. (2010). Nossa contribuição é considerar uma parcela da renda esperada como colateral para empréstimos das famílias. Nós estimamos o modelo proposto para o Brasil utilizando estimação Bayesiana e encontramos que economias que sofrem restrição de colateral por parte das famílias tendem a sentir o impacto de choques monetários mais rapidamente devido a exposição do setor bancário a mudanças no salário esperado.