Risks are usually represented and measured by volatility-covolatility matrices. Wishart processes are models for a dynamic analysis of multivariate risk and describe the evolution of stochastic volatility-covolatility matrices, constrained to be symmetric positive definite. The autoregressive...

This article considers large portfolios of assets submitted to both systematic and unsystematic (or idiosyncratic) risks. The idiosyncratic risks can be fully diversified if the portfolio size is infinite, but only partly diversified otherwise. The granularity adjustment measures the effect of...