The Commissioner of Competition, Matthew Boswell said in a recent speech that “it’s not bad to be big” while outlining the noteworthy legislative changes to the monopolistic practices provisions of the Competition Act. He added that “companies that grow large by innovating and competing on the merits should not be punished”. While high levels of market concentration can indicate potential monopolistic practices, modern competition policy recognizes that high market share alone should not be a concern.  Instead, the competitive dynamics of the market, consumer welfare, and the behaviour of the firms within the market must be considered to accurately assess the implications of market concentration. That being said, the recent amendments to the merger provisions which repealed the efficiency defence, introduced U.S. style rebuttable market concentration presumptions and now permit mergers to be blocked on the basis of market shares alone suggest that proposed mergers in concentrated sectors could be in for a bumpy ride from the Competition Bureau.