Inflation and debt indexation : the equivalence of two alternative schemes for the case of periodic payments

The presence of inflation has induced the financial institutions to implement procedures devised to protect the real values of theirs loans. Two of such procedurcs, the floaaing rale scheme and the monetary correction mechanism, tend to lead to very different streams of payments. However, whenever the floating rate scheme follows the rule of Strict adhercnce to lhe Fisher equation, lhe two procedures are financially equivalent.

Collateral avoids Ponzi schemes in incomplete markets

Without introducing neither debt constraints nor transversality conditions to avoid the possibility of Ponzi schemes, we show existence of equilibrium in an incomplete markets economy with a collateral structure.

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.

Financial disruption as a cost of sovereign default

This dissertation analyses quantitatively the costs of sovereign default for the economy, in a model where banks with long positions in government debt play a central role in the financial intermediation for private sector's investments and face financial frictions that limit their leverage ability. Calibration tries to resemble some features of the Eurozone, where discussions about bailout schemes and default risk have been central issues. Results show that the model captures one important cost of default pointed out by empirical and theoretical literature on debt crises, namely the fall in investment that follows haircut episodes, what can be explained by a worsening in banks' balance sheet conditions that limits credit for the private sector and raises their funding costs. The cost in terms of output decrease is though not significant enough to justify the existence of debt markets and the government incentives for debt repayment. Assuming that the government is able to alleviate its constrained budget by imposing a restructuring on debt repayment profile that allows it to cut taxes, our model generates an important difference for output path comparing lump-sum taxes and distortionary. For our calibration, quantitative results show that in terms of output and utility, it is possible that the effect on the labour supply response generated by tax cuts dominates investment drop caused by credit crunch on financial markets. We however abstract from default costs associated to the breaking of existing contracts, external sanctions and risk spillovers between countries, that might also be relevant in addition to financial disruption effects. Besides, there exist considerable trade-offs for short and long run path of economic variables related to government and banks' behaviour.

On the construction of explicit exponential based schemes for Stiff SDEs

Trabalho apresentado Numerical Solution of Differential and Differential-Algebraic Equations (NUMDIFF-14), Halle, 7-11 Sep 2015