Testing the Weak Form of Efficient Market Hypothesis: Empirical Evidence from Equity Markets

The aim of this paper is to analyse integration and test the hypothesis of an efficient market, in its weak form, in sixteen international financial markets. The sample covers the period from January 2002 to July 2019 and is divided into three sub-periods. In order to achieve such an analysis, the aim is to provide answers to two questions. Has the global financial crisis intensified the financial integration of international markets? If there is a process of mean-reversion in the international stock markets, with arbitrage, the hypothesis of portfolio diversification will be feasible? The results suggest that the global financial crisis has intensified the integration level of international financial markets. Regarding random walk and market efficiency hypotheses, in its weak form, the results suggest the existence of a mean-reversion and the rejection of the hypothesis of information efficiency, in its weak form, in developed and emerging markets, European and non-European. In terms of portfolio diversification analysis, we see that levels of financial integration decreased significantly in the sub-period following the global financial crisis, namely with its respective benchmarks, such as the US market, Japan and Hong Kong. We can assess the existence of feasible diversification opportunities in the long term.