The impact of insider ownership and institutional ownership on post-earnings-announcement-drift: Evidence from Vietnam

In this study, we first document the existence of post-earnings-announcement-drift (PEAD) in Vietnam, consistent with investors' under-reaction to earnings surprises. We then investigate whether and how institutional ownership and insider ownership affect PEAD. We find that the magnitude of PEAD effect is stronger among firms with higher insider ownership. We argue that higher insider ownership may increase information opacity and impede efficient processing of earnings news among investors. We provide supporting empirical evidence for this argument. Furthermore, in contrast to the conventional view that institutional investors exploit PEAD and accelerate the speed of price discovery, we find that institutional investors do not have significant impacts on PEAD. We argue that this result is consistent with recent findings in the US and China that some institutional investors may herd, hence, not necessarily help to mitigate PEAD. Our findings provide useful insights about the effect of insider investors and institutional investors on the delayed response to earnings news in the context of Vietnam.