Stock return comovement and Korean business groups

This paper explores whether business group affiliations affect the covariance structure of stock returns in Korea. We find that the stock returns of firms belonging to the same business group show positive and significant comovement. The strong comovement between group returns and firm returns is explained by correlated fundamentals. We find strong comovement among business group affiliate earnings. Moreover, variance decomposition of returns shows that cash flow news plays a relatively more important role in explaining group comovement than discount rate news, suggesting a link between stock return comovement and the “tunneling” and “propping” behaviors of business groups. Finally, return comovement increases when a firm joins a business group.