Does information asymmetry vary between insiders in different industries

Abstract

In this master thesis, we examine the level of private information of insiders on the Oslo Stock Exchange. We contribute to the understanding of the issue by recognizing how the sector characteristics influence insider return. First, we allocate each firm into its adjoining sector before we divide the sectors into two groups, Exogenous and Endogenous. The first group contains insiders in sectors where exogenous factors steer much of the stock price, while the second group has insiders in sectors with low exposure towards these factors. By doing so we hope not only to isolate the sector characteristics, but also to get two groups that is well-constructed for testing against each other. We apply a long-term event study of one year, where we investigate the abnormal return of the two groups. A particular challenge in our long-term study is to measure the underlying risk between the two groups. This is critical, as even a small error in risk adjustment could accumulate to significant misrepresentation of the abnormal return. To control for estimation error, we use a factor model containing factors that Skjeltorp, Næs and Ødegaard (2011) have shown fits the Norwegian market. We conclude that sectors have a large impact on insider’s abnormal return. The insiders that we classify as Endogenous outperformed the Exogenous group with 5.85%, showing possession of superior predictability. Additionally, if outsiders where to follow buy trades of the Endogenous group, our results suggest that they can earn abnormal return. We therefore find support of the weak-form of efficiency.