Web searches made with Google are used more and more by financial investors. Therefore,such internet activities are expected to result in significant trading on stock exchanges. This thesis aims to analyze data on search behavior in Google as a measure for retail investor's attention. The main question investigated is whether an increase in retail attention affects trading on German exchanges Xetra, Börse Frankfurt and Tradegate. Empirical results confirm that increased Google search volume results in a higher trading activity on all exchanges. The impact seems to be higher on exchanges with a stronger retail investor presence.