In a recent contest a clairvoyant, a four year old little girl and a financial expert were asked to manage stock portfolios during a week. The little girl has outperformed the two other contestants. This should remind us that it's impossible to predict changes in the stock markets. It should also remind investors that index funds are better investing vehicles than actively managed ones.
AFTALION, F. (2001). La Bourse et les experts. Les Echos, pp. 69.