The study looks at how mergers impact profits and market shares in markets where a few big companies are fighting for customers. By examining data from the European Commission, the researchers figure out how merging companies affect their competitors. They find that when a merger reduces competition from, say, five to four companies, the remaining firms tend to make more products and earn higher profits. Surprisingly, the companies joining forces in the merger actually see their earnings drop as a result. So, big mergers seem to give more market power to survivors than to those that merge.