Well it depends on your definition of efficiency. In a perfectly competitive (and perfect information) marketplace there will be more goods sold than in a monop

Well it depends on your definition of efficiency. In a perfectly competitive (and perfect information) marketplace there will be more goods sold than in a monopolistic one. So in terms of resource allocations its inefficient. There's a graph on this page title "Perfect Competition, Monopoly, and Efficiency" [1] that shows how since the monopoly can price set they choose a higher price than where demand meets supply since it results in higher profits. This isn't achievable in a competitive marketplace as then somebody else would just undercut them. Interestingly you can correct this inefficiency by subsidizing a monopoly so that it offers the correct amount of supply. [1]: https://saylordotorg.github.io/text_principles-of-microeconomics-v2.0/s13-03-assessing-monopoly.html https://saylordotorg.github.io/text_principles-of-microecono...