The impact of institutional ownership and valuation on stock price around SET50 index inclusion and exclusion

Abstract

This study examines the impact of institutional ownership and valuation on stock price around the changes in index constituents. Specifically, this paper studies the significant SET50 index during the period of 2014 – 2021. According to the empirical result, there is an asymmetric price response between index additions and index deletions. The effects from exclusions are considerably stronger than from inclusions. The findings also show that percentage ownership of institutional investors and abnormal return are positively correlated in case of exclusions but not for inclusions (though insignificant). Companies deleted from the index result in lower institutional holdings and subsequently exhibit lower share prices. Moreover, stock valuation has no effect on stock price in response to the announcement of index inclusion and exclusion.