use a novel database that identifies over 20,000 product/geographic antitrust markets affected by over2,000 mergers …

Worldwide, the overwhelming majority of large horizontal mergers are cleared by antitrust authorities unconditionally …. The presumption seems to be that efficiencies from these mergers are sizeable. We calculate the compensating efficiencies … that would prevent a merger from harming consumers for 1,014 mergers affecting 12,325 antitrust markets scrutinized by the …