When Safety Becomes a Trap: How Portfolio Diversification Collapses Under Market Stress
Diversification is the foundational promise of modern portfolio construction — spread your risk across uncorrelated assets and survive any storm. But history repeatedly demonstrates that the very moment diversification is needed most, correlations converge toward 1.0 and the protection evaporates. Understanding why this happens, and how to build around it, is one of the most consequential skills an active trader can develop.