Voici un petit commentaire que j'ai mis en réponse sur un autre blog:
When the markets are falling as now, diversification does not work well. Why? Because of diversification of all the people on market: pension funds, mutual funds, associations, private investors, EVERYONE DIVERSIFIES. There is a very high correlation between market moves of good shares and bad shares when the stocks are moving down. So too much diversification just diminish your returns but doesn't contribute to diminish risk from the Modern portfolio theory point of view.
When the markets are falling as now, diversification does not work well. Why? Because of diversification of all the people on market: pension funds, mutual funds, associations, private investors, EVERYONE DIVERSIFIES. There is a very high correlation between market moves of good shares and bad shares when the stocks are moving down. So too much diversification just diminish your returns but doesn't contribute to diminish risk from the Modern portfolio theory point of view.
