Most [Many] investment managers are uncomfortable when the construction of the portfolios strays much from the S&P 500. Stock selection is often a byproduct of whether to underweight or overweight this or that industry relative to its makeup in the index. Those decisions, in turn, are heavily influenced by the near-term outlook. Everyone wants to belong to those groups that are “acting well” (going up fast) and underweight those that are lagging.
Bill Miller, CFA