Hola, haciendo la ronda nocturna me he dado de bruces con otra comentario sobre el tema, esta vez son los chicos de Sequoia en el annual report de 2012
"Given the huge run up in equities since early 2009, we are no longer finding compelling valuations, either for our existing holdings or for new ideas we are researching. Our current portfolio seems fairly valued today. That said, anyone who has paid attention over the past 15 years knows equities can trade at extreme levels, both of overvaluation and undervaluation.
Valuations for stocks are heavily influenced by interest rates, and particularly by the risk-free rate of return on 10-year and 30-year United States Treasury bonds. Relative to the current return on Treasury Bonds, stocks continue to be quite attractive. However, the current risk-free rate of return is not a product of market forces. Rather,it is an instrument of Federal Reserve policy. As long as these policies remain in place, and stocks trade at higher levels of valuation, it will be more difficult for us to find individual stocks that meet our criteria for returns on a risk basis that incorporates substantially higher interest rates than exist currently. Just as we think it would be a mistake for investors to buy bonds at current levels, we believe it would be a mistake for us to buy stocks on the assumption that interest rates remain anywhere near current levels."