Productivity and stock prices

This study looks at the degree of correlation between stock prices and productivity at different levels, i.e. analysis of the correlations between certain components of the two variables and how correlations vary according to the different frequencies characterising these variables. It should be acknowledged that the approach used is only designed to isolate the stylised facts related to the cyclical components of the variables under review and not to explain them. In particular, the method chosen cannot be used to make forecasts or to provide a refi ned economic interpretation of these stylised facts. Nonetheless, this analysis, applied to the United States and the euro area over the period 1973(1)-1985(4), highlights the following points: • in the United States, an increase (or reduction) in the cyclical component of the rate of stock returns is positively correlated with current or future increases (or reductions) in that of the productivity growth rate; • in the euro area, this correlation is less strong. It appears, for example, that a sharp fall in stock prices precedes a marked decline in productivity (link between stock prices and future productivity) and, as a result, in profi ts. This fall could then be interpreted as a normal, even desirable, adjustment mechanism for asset prices. Correspondingly, a sharp rise in stock prices should not automatically be interpreted as the emergence of a future bubble given that such rises appear to foreshadow an increase in productivity and therefore in profi ts. Over the most recent period 1986(1)-2002(4), these correlations appear less pronounced, thus indicating a possible break. Our result is robust given that two complementary methods corroborate it and that it is similar to Estrella’s (2003) findings for the United States. This pattern appears to suggest that the cyclical component of stock prices is in phase with that of productivity.