‘There are the standard numbers people throw around but I think most people would say you have to decide whether search ad is a market for antitrust proposes. If it is, that’s a high enough share. But you also have to look at issues of entry and issues of fragility. How stable is that share and how intense is that market,’ Schmalensee said.
‘There’s no magic threshold but with high share levels, you get to be concerned,’ he continued. ‘On the other hand, monopolists are allowed to compete. The question is whether the arrangement would stifle competition.’