Retail market structure refers to the number of companies that sell similar or identical products in the same geographical area. An oligopoly describes a small group of companies that collude to raise ...
Caves, R. E., and M. E. Porter. "Market Structure, Oligopoly and the Stability of Market Shares." Journal of Industrial Economics 26, no. 4 (June 1978): 289–313.
Three firms dominate the target date fund market, constituting an oligopoly. One firm – Vanguard – owns 72% of the passive TDF market, constituting a monopoly. Oligopolies and monopolies are bad. They ...