This article investigates the post-merger performance effects resulting from mergers and acquisitions (M&As), drawing on a representative sample taken from all Swiss M&As occurring between 2006 and 2008, the majority of which took place between small and medium-sized firms (SMEs). Using this data, the study was able to investigate the impact of M&As on differing measures of economic performance, and also on innovation for the post-merger period of 2008–2010. The study found positive statistically significant performance effects arising from M&As for three of five critical performance indicators utilized. Furthermore, the evidence suggests that growth is a principal motive for external mergers, while efficiency is more influential on internal mergers.