Horizontal mergers are usually under the scrutiny of antitrust authorities due to their potential undesirable effects on prices and consumer surplus. Ex-post evidence, however, suggests that not always these effects take place and even relevant mergers may end up having negligible price effects....

When it examines the risk of coordinated effects, an antitrust authority will usually compare the situation where the merger is accepted with an attendant risk of collusion with the benchmark case in which competition is present ex-post. The main objective of this paper is to show that the...