Yeah, it's a major consideration when determining if a merger should happen, e.g. Krogers. Just because its more efficient doesn't mean you get consumer benefit because you should expect them to profit maximize with monopoly rents. I mean definitely +1 on nationalize them rather than let capitalism go unfettered, but I'm making a general observation that large companies can only be large because they can extract monopoly rents, rather than just a barrier to entry to match efficiencies of scale thing.