For just the supermarkets, yes. But S-group and Kesko are huge. They own restaurants, banks, hotels, gas stations, home improvement stores, department stores, car dealerships, and a bunch of specialty stores.
Yeah, I used "retail sector" quite carefully there. The breadth of the conglomerates here is vast. It's sort of surreal to me, even by American standards, that this level of market capture is even allowed.