A market structure dominated by a small number of large buyers controlling the buying-side of a market. Oligopsony is the somewhat obscure and seldom discussed buying counterpart to an oligopoly seller that controls the selling side of a market. Whereas oligopoly is most relevant to product markets, oligopsony is most relevant to factor markets.
An oligopsony is a market form in which the number of buyers is small while the number of sellers in theory could be large. This typically happens in market for inputs where a small number of firms are competing to obtain factors of production. It resembles an Oligopoly, where there are many buyers but just a few sellers.