Overreaction Hypothesis and Reaction of Borsa Istanbul to Dow-Jones

Abstract

The aim of this study is to investigate whether or not there are any over-reactions to the positive and negative events of the Borsa Istanbul 100 index (BIST-100) in relation to the Dow Jones Industrial index (DJIA).  The daily stock indexes between January 2010 and June 2016 are used in this research. The research finding showed that BIST-100 reacts in the same way as DJIA up to 3.31% and the reaction decreases and was lost between 30 and 60 days against the positive changes. In case of adverse events the BIST 100 shows abnormal decline in protecting the efficient market hypothesis is valid for 30 days after the event, however, the decline is reversed until the 60’th days when all losses are compensated. This terminates the validity of the efficient market hypothesis. This study shows that the BIST 100 index does not comply with the efficient market hypothesis and demonstrate the validity of the overreaction hypothesis. Study results include stock investments, whose findings will have an impact on portfolio management decisions of investors.