In merger analysis, ease of entry, when present, trumps competitive concerns and allows market behavior, such as a merger, to proceed unchallenged. Thus, entry plays a key role in every antitrust study. That said, it is surprising that entry analysis is inconsistently defined, both in the courts...

Barriers to entry are a necessary, but not sufficient condition for a merger to adversely affect competition. As a barrier definition must be linked to the specific theory of competitive concern under review to be meaningful, a theoretical barrier definition is unlikely to be useful. Instead, an...