In this paper we review and generalize results on the derivation of tractable non-negativity (necessary and sufficient) conditions for N-dimensional asymmetric power GARCH/HEAVY models and MEM. We show that these non-negativity constraints are translated into simple matrix inequalities, which...

The OGARCH specification is the leading model for a class of multivariate GARCH (MGARCH) models that are based on linear combinations of univariate GARCH specifications. Most MGARCH models in this class adopt a spectral decomposition of the covariance matrix, allowing for heteroskedasticity on...

Recently, independent of each other, there has been interest in (i) time-variation in higher-order moments; (ii) idiosyncratic skewness and predictability of skewness in the asset pricing context; and (iii) robust measures of skewness and kurtosis. The second literature questions the usefulness...

We derive the multivariate moment generating function (mgf) for the stationary distribution of a discrete sample path of n observations of a square-root diffusion (CIR) process, X(t). The form of the mgf establishes that the stationary joint distribution of (X(t(1)),...,X(t(n))) for any fixed...

We introduce a smooth transition Generalized Pareto (GP) regression model to study the link between extreme losses and the economic context. The advantage of our approach consists in specifying a time-varying dependence structure between financial factors and the severity distribution of the...

The sample skewness and kurtosis of macroeconomic and financial time series are routinely scrutinized in the early stages of model-building and are often the central topic of studies in economics and finance. Notwithstanding the availability of several robust estimators, most scholars in...

The correlations among assets returns is one of the key components in the construction of a diversified portfolio. It has been observed though that in time of great distress, when a drop in financial markets occurs, correlations tend to increase. As a consequence, the diversification effect is...