Scenario Modeling of Selective Hedging Strategies

We study currency risk management in the context of scenario analysis. We develop scenario-based optimization models that jointly determine the portfolio composition and the hedging strategy within each currency. Thus the model prescribes optimal selective hedging policies. We then study empirically the performance of the models. The new elements of our empirical analysis are: various horizons (one month and one semester), various currency bases, explicit incorporation of realistic transaction costs. The results show that transaction costs are very important in determining the profitability of various currency risk management strategies for both stocks and bonds at the one month horizon.

Scenario Modeling for the Management of International Bond Portfolios

We address the problem of portfolio management in the international bond markets. Interest rate risk in the local market, exchange rate volatility across markets, and decisions for hedging currency risk are integral parts of this problem. The paper develops a stochastic programming optimization model for integrating these decisions in a common framework. Monte Carlo simulation procedures, calibrated using historical observations of volatility and correlation data, generate jointly scenarios of interest and exchange rates. The decision maker's risk tolerance is incorporated through a utility function, and additional views on market outlook can also be incorporated in the form of user specified scenarios. The model prescribes optimal asset allocation among the different markets and determines bond-picking decisions and appropriate hedging ratios. Therefore several interrelated decisions are cast in a common framework, while in the past these issues were addressed separately. Empirical results illustrate the efficacy of the simulation models in capturing the uncertainties of the Salomon Brothers international bond market index.

Microscopic understanding of heavy-tailed return distributions in an agent-based model

The distribution of returns in financial time series exhibits heavy tails. In empirical studies, it has been found that gaps between the orders in the order book lead to large price shifts and thereby to these heavy tails. We set up an agent based model to study this issue and, in particular, how the gaps in the order book emerge. The trading mechanism in our model is based on a double-auction order book, which is used on nearly all stock exchanges. In situations where the order book is densely occupied with limit orders we do not observe fat-tailed distributions. As soon as less liquidity is available, a gap structure forms which leads to return distributions with heavy tails. We show that return distributions with heavy tails are an order-book effect if the available liquidity is constrained. This is largely independent of the specific trading strategies

Tourism Specialization and Sustainability: A Long-Run Policy Analysis

This study focuses on the dynamic evolution of a small open economy specialized in tourism based on natural resources when tourist services are supplied to foreign tourists who are crowding-averse and give positive value to the environmental quality. We analyse the steady-state properties and run several policy exercises in two versions of our model: in the first, private agents income is spent entirely on consumption while, in the second, agents are allowed to invest part of their income in pollution abatement technology (PAT) which artificially increases the rate of regeneration of the environmental asset. A unique locally saddle point equilibrium is found in both versions and for both the market and the centralized solution. Our main findings are that: 1) a corrective income tax raises steady state utility in both versions but is capable of leading the economy in its first-best dynamic path only when agents cannot invest in the PAT; 2) when the PAT is available to the government but not to agents, an income tax which finances abatement expenditures may increase steady state utility with respect to the market solution when the natural regeneration rate of the environment and the degree of crowding-aversion are both low enough; 3) when PAT is available, the market chooses to devote a higher fraction of income to abatement than the central planner but in both cases this fraction is positive only if the natural rate of regeneration is not too large; 4) when PAT is available an income pollution tax does not affect the dynamic path of the market economy

The effect of asymmetries on stock index return value-at-risk estimates

It is widely accepted that equity return volatility increases more following negative shocks rather than positive shocks. However, much of value-at-risk (VaR) analysis relies on the assumption that returns are normally distributed (a symmetric distribution). This article considers the effect of asymmetries on the evaluation and accuracy of VaR by comparing estimates based on various models