Insider trading on the German capital market — Can insiders achieve excess returns through their information advantage?

Abstract

This study investigates whether corporate insiders can generate excess returns on the German capital market due to their information advantage. This is done with the help of an event study based on a market model that estimates the expected returns. Furthermore, the effect size of individual aspects is examined in a multiple regression. It is shown that insiders can achieve short-term excess returns of up to 2.1% after purchases and of up to -2.95% after sales. Moreover, these are strikingly high for, relative to market capitalization, transactions of smaller firms and transactions of other executives. The greatest influence on the excess return of a transaction is the market capitalization of the company in the case of buy transactions, while the excess return of sell transactions is largely determined by the share of trading volume in the outstanding shares. An imitation of insider transactions by outsiders may allow for excess returns, but this strongly depends on the share to be traded due to the bid-ask spread as well as the trading commissions. Despite the existence of regulation, it is evident that insiders can achieve significant excess returns, presumably on the basis of non-public information