In today's globalized business world, it has become easier to get information from both the market and the companies. This leads to the fact that, from the last decades, companies are continuously expanding through mergers & acquisitions through the need for constant development and optimization of asset value. But how does it look in reality? What conditions do we have in Sweden in relation to outside markets such as, for example, USA and the rest of Europe? As both institutional and cultural conditions differ from one country to another, it may result in mergers & acquisitions being different. Underlying variables that affect the excess return on mergers & acquisitions differ depending on where the mergers or acquisitions occurs. Hostile acquisitions in the United States clearly show that it gives a negative excess return, while in Europe it shows that it was the hostile acquisitions that generated a positive excess return. How is it in Sweden? To find out how the excess return looks like in Sweden and to find out what kind of underlying variables affect the excess return, we made a quantitative event study between 2003 and 2015. During this period, we found 64 Swedish companies that met the study criteria. In this study, we found that the excess return generated a more positive over return for target companies than bidding companies, which is consistent with previous research in the area. The underlying variables that affect the excess return in Sweden are as follows: Type of tender, method of payment and partial cross-border merger and acquisition (target companies).