Evaluating portfolio Value-at-Risk using semi-parametric GARCH models

In this paper we examine the usefulness of multivariate semi-parametric GARCH models for evaluating the Value-at-Risk (VaR) of a portfolio with arbitrary weights. We specify and estimate several alternative multivariate GARCH models for daily returns on the S&P 500 and Nasdaq indexes. Examining the within-sample VaRs of a set of given portfolios shows that the semi-parametric model performs uniformly well, while parametric models in several cases have unacceptable failure rates. Interestingly, distributional assumptions appear to have a much larger impact on the performance of the VaR estimates than the particular parametric specification chosen for the GARCH equations.     

Volatility forecasts and at-the-money implied volatility: a multi-component ARCH approach and its relation to market models

This article explores the relationships between several forecasts for the volatility built from multi-scale linear ARCH processes, and linear market models for the forward variance. This shows that the structures of the forecast equations are identical, but with different dependencies on the forecast horizon. The process equations for the forward variance are induced by the process equations for an ARCH model, but postulated in a market model. In the ARCH case, they are different from the usual diffusive type. The conceptual differences between both approaches and their implication for volatility forecasts are analysed. The volatility forecast is compared with the realized volatility (the volatility that will occur between date t and t + ΔT), and the implied volatility (corresponding to an at-the-money option with expiry at t + ΔT). For the ARCH forecasts, the parameters are set a priori. An empirical analysis across multiple time horizons ΔT shows that a forecast provided by an I-GARCH(1) process (one time scale) does not capture correctly the dynamics of the realized volatility. An I-GARCH(2) process (two time scales, similar to GARCH(1,1)) is better, while a long-memory LM-ARCH process (multiple time scales) replicates correctly the dynamics of the implied and realized volatilities and delivers consistently good forecasts for the realized volatility.     

Estimating correlation and covariance matrices by weighting of market similarity

We discuss a weighted estimation of correlation and covariance matrices from historical financial data. To this end, we introduce a weighting scheme that accounts for the similarity of previous market conditions to the present situation. The resulting estimators are less biased and show lower variance than either unweighted or exponentially weighted estimators. The weighting scheme is based on a similarity measure that compares the current correlation structure of the market to the structures at past times. Similarity is then measured by the matrix 2-norm of the difference of probe correlation matrices estimated for two different points in time. The method is validated in a simulation study and tested empirically in the context of mean–variance portfolio optimization. In the latter case we find an enhanced realized portfolio return as well as a reduced portfolio risk compared with alternative approaches based on different strategies and estimators.     

On the distribution of dividend payments and the discounted penalty function in a risk model with linear dividend barrier

In the framework of classical risk theory we investigate a model that allows for dividend payments according to a time-dependent linear barrier strategy. Partial integro-differential equations for Gerber and Shiu's discounted penalty function and for the moment generating function of the discounted sum of dividend payments are derived, which generalizes several recent results. Explicit expressions for the nth moment of the discounted sum of dividend payments and for the joint Laplace transform of the time to ruin and the surplus prior to ruin are derived for exponentially distributed claim amounts.     

Time inconsistency and delayed retirement decision: the French pension bonus

With the increase in life expectancy and demographic shocks, several public policies in the last decades aim to encourage individuals to postpone retirement. One of them, the pension bonus, gives an increased pension if individuals retire beyond their Full Retirement Age. Previous ex post analyses found that the responsiveness to this type of financial incentives, which encourage to postpone retirement, is heterogeneous among agents and that the global effect is rather limited. Deriving from previous research in Behavioural Economics, this article analyses the impact of time inconsistency in the decision to delay retirement to get the bonus. Using public national survey data, short-term and long-term impatience are measured with questions on retiring motivations. After controlling for the endogeneity of the bonus knowledge, econometric results show that time-inconsistent agents are less likely to retire with the bonus.     

Pushing speed? The marketing of fast and convenience food

The Menu: This paper explores the complex relationship between the marketing of fast and convenience food, and Western constructions and experiences of time in late Modernity, through a polemical analysis of a set of recent British television advertisements for a variety of brands in this sector. A cursory reading of these ads reveals some apparent contradictions in the deployment of time in fast/convenience food marketing: they seem to celebrate both speed (time as “sameness” and “continuity”) and nostalgia (time as “difference” and “discontinuity”). We go beyond a simple understanding of these alternative tropes as indices of competing brand strategies by interpreting their wider relations to the systemic and cultural vicissitudes of contemporary global capital. We conclude that the temporal articulation of fast and convenience foods presented in the ads is not in fact paradoxical, but dialectical. This dialectical relationship is an essential and continuing ideological structure of late Modernity.     

Tariffs,trade and unemployment in a disequilibrium model: issues and policies

This paper studies the disequilibrium transition process engaged by increased openness to trade, and the effect of institutions, market behaviors and economic policies on that transition. The issue is analyzed with a simple two country (north and south), two goods model, amended in order to take into account the time dimension of both the production and the decision processes. Investigating the consequences of a tariff decrease by means of numerical simulations, we show to what extent wage and price setting, and the degree of tightness of monetary policy affect the outcome of the disequilibrium process. The main result is that capturing the gains associated with international trade requires market behaviors and economic policies, which are rather different from what is usually prescribed.

论项目投资评价中的时间风险值效应及其选择

基于现行现金流折现的项目投资评价的有效性取决于对项目现金流量预测的正确性,而项目现金流量具有预测发生的时间越遥远,现金流量不确定性的程度越大但又趋于相对稳定的特征.从这一特征出发,本文引入时间风险值进行折现调整这种系统可循的方法来解决在投资评价时难以预计的项目现金流量未来的不确定性问题,从而使不确定性条件下的项目投资评价更具有客观性.