Overlapping portfolio holdings and unique sources of emerging market risk

Momentum, size, and low volatility in emerging markets regularly exhibit increased correlations across factors and markets in periods of negative returns. I provide a framework to distinguish a unique source of risk from a set of factors in the stage of portfolio formation. The framework is based on discarding duplicate positions that exceed half the portfolios in periods of factor comovement. Unique factors eliminate rising correlation and factor crashes. The results are robust for the most recent financial shocks. For practitioners, the approach helps in distinguishing original investment strategies and provides opportunities for active management in emerging markets.