In some industries a monopoly can even be with a marketshare about 25%, but nevermind, 50% is widely regarded as the average threshold, as you can see on justic

In some industries a monopoly can even be with a marketshare about 25%, but nevermind, 50% is widely regarded as the average threshold, as you can see on justice.gov :( "Some courts have stated that it is possible for a defendant to possess monopoly power with a market share of less than fifty percent.(29) These courts provide for the possibility of establishing monopoly power through non-market-share evidence, such as direct evidence of an ability profitably to raise price or exclude competitors. The Department is not aware, however, of any court that has found that a defendant possessed monopoly power when its market share was less than fifty percent.(30) Thus, as a practical matter, a market share of greater than fifty percent has been necessary for courts to find the existence of monopoly power.(31)" https://www.justice.gov/atr/competition-and-monopoly-single-firm-conduct-under-section-2-sherman-act-chapter-2 https://www.justice.gov/atr/competition-and-monopoly-single-...