The relationship is observed for the S&P 500 index between ~1980 and ~2005 but data outside of this time window, or in different international markets do not show the same pattern.

http://en.wikipedia.org/wiki/Fed_model

Data selection and international markets

The Fed model equilibrium was only observed in one market, and for a limited time window. More specifically, the relationship is observed for the S&P 500 index between ~1980 and ~2005 but data outside of this time window, or in different international markets do not show the same pattern.