What Is Monopsony? One Buyer Rather Than One Seller

A monopolist restricts what it sells to raise the price, and a monopsonist restricts what it buys to lower it, which is the same logic applied from the other side. In a labour market, an employer with power over wages faces an upward-sloping supply of workers, meaning that hiring more requires offering more, and because raising the wage generally means raising it for existing workers too, the true cost of an additional hire exceeds the wage paid. That gap causes the employer to hire fewer workers than a competitive market would and to pay less than the value those workers produce. The result is lower wages and lower employment together, which is the crucial prediction and which distinguishes this situation from a competitive market in an important way.

Complete dominance is rare and partial power is common, arising from several sources:

• •Geographic concentration, where one employer dominates a local labour market and moving is costly
• •Specialised skills with few possible employers, which describes many professions
• •Search costs and imperfect information, which limit how readily workers move even where alternatives exist
• •Non-compete agreements and no-poach arrangements, which restrict movement directly and have attracted enforcement action
• •Licensing and immigration status tied to an employer, which removes the ability to leave
• •Buyer concentration in supply chains, where a small number of retailers or processors face many producers

The concept is central to a long-running dispute about minimum wages. Standard competitive analysis predicts that a wage floor above the market rate reduces employment, which was the received position for decades. Under buyer power the prediction reverses over a range, since a floor forces the employer to pay more and removes the incentive to restrict hiring, so a minimum wage can raise both wages and employment up to a point. Empirical work from the 1990s onward, particularly studies comparing neighbouring areas across a policy boundary, found employment effects far smaller than the competitive model predicted and sometimes positive, which was contested fiercely and has been substantially accepted. That evidence is a major reason buyer power moved from a footnote to a central concept, and it was recognised with a Nobel Prize in 2021.

Establishing how much buyer power exists in a market is an empirical problem with several approaches. Concentration measures count how much of the hiring in a local labour market is done by a few employers, and studies applying them find that many local markets are considerably more concentrated than national figures suggest, since a worker in a particular occupation in a particular town may face very few realistic employers. Estimating how responsive labour supply is to wages at the level of an individual firm is the more direct measure, since perfect competition implies that a firm cutting pay slightly loses all its workers, and the estimates consistently find far less responsiveness than that. Separation rates in response to pay differences give another measure. The general finding across methods is that labour markets are substantially less competitive than the textbook model assumes.

Taking the concept seriously changes what looks like a problem and what looks like a remedy. Competition enforcement has traditionally examined effects on consumers through prices, and buyer power harms workers and suppliers instead, which is invisible to that test, so several jurisdictions have begun examining labour market effects of mergers explicitly. Non-compete agreements have been restricted or banned in several places on exactly this reasoning. Collective bargaining is analysed as a countervailing power that offsets buyer power rather than as a distortion. Transparency about pay reduces the information asymmetry the arrangement depends on. And the argument extends beyond labour to agricultural supply chains and to platform markets, where many small suppliers face few buyers and the same analysis applies.

One dominant buyer restricts purchases to lower the price, which in a labour market means hiring fewer workers and paying less than they produce. Geographic concentration, specialised skills and restrictions on movement all create partial versions. Under buyer power a minimum wage can raise employment as well as wages, which is why empirical findings of small employment effects moved the concept to the centre.