a1 firstname.lastname@example.org, ISCTE Business School-Lisbon, CEMAF/ISCTE, Complexo INDEG/ISCTE, Av. Prof. Anibal Bettencourt, 1600–189 Lisboa, Portugal
a2 email@example.com, ISCTE Business School-Lisbon, University of Coimbra, Faculdade de Economia, Avenida Dias da Silva, 165, 3004–512 Coimbra, Portugal.
This paper uses a volatility decomposition method to study the time-series behavior of equity volatility at the world, country, and local industry levels. Between 1974 and 2001, there is no noticeable long-term trend in any of the volatility measures. Then in the 1990s there is a sharp increase in local industry volatility compared to market and country volatility. Thus, correlations among local industries have declined. More assets are needed to achieve a given level of diversification, and there is more of a penalty for not being well diversified by industry. Local industry volatility leads the other volatility measures.