A new model-based approach to measuring time-varying financial market integration

We investigate financial market integration by looking at the stock market linkages of five developed countries (France, Germany, Japan, the UK, and the US) over the period 1970:1- 2010:8. We measure the time-varying degree of world stock market integration of each country through the conditional variance of the country-specific premium in equity excess returns. The country-specific premiums are derived theoretically from an international CAPM with market imperfections. They are estimated from the latent factor decomposition implied by the theory through the use of state space methods that allow for GARCH errors. Our empirical results suggest that stock market integration has increased over the period 1970:1-2010:8 in all countries but Japan. And while there is a structural increase in stock market integration in four out of five countries, all countries also exhibit several shorter periods of disintegration (reversals), i.e. periods in which country-specific shocks play a more dominant role. Hence, stock market integration is measured as a dynamic process that is fluctuating in the short run while gradually increasing in the long run.