Starting from the Merton framework for firm defaults, we provide the analytics and robustness of the relationship between default correlations. We show that loans with higher default probabilities will not only have higher variances but also higher correlations between loans. As a consequence,...

Portfolio diversification and hedging have become more complicated in large part due to adverse developments in the time-varying behavior of correlations, and consequently there is renewed appreciation for understanding how correlation dynamics affect the diversification and hedging properties...

We study the effects of correlation ambiguity on portfolio choice in a market with multiple risky assets. We find that the optimal portfolio contains only a fraction of risky assets under correlation ambiguity, and in particular, just one risky asset enters the optimal portfolio if the level of...

In the field of portfolio management, practitioners are focusing increasingly on risk-based portfolios rather than on mean-variance portfolios. Risk-based portfolios are constructed based solely on covariance matrices, and include methods such as minimum variance (MV), risk parity (RP), and...