What do we call an industry where only a few companies hold the majority of market power?

Explanation

A colluding industry involves companies working together to control prices, which is not necessarily the same as market dominance by few firms. A merged industry results from companies combining but does not always imply few dominant firms. A concentrated industry is characterized by a small number of firms controlling most of the market share. A natural monopoly occurs when a single firm can supply the market more efficiently than multiple firms. Therefore, the correct term for an industry dominated by a few firms is a concentrated industry.