Monopsony and market power in the labor market: We’ve all heard the term “monopoly,” even if it’s just in the context of the board game. But a related term, or even another face of monopoly, is monopsony. A monopsony is when a firm is the sole purchaser of a good or service whereas a monopoly is when one firm is the sole producer of a good or service. Most examples of monopsony have to do with the purchase of workers’ time in the labor market, where a firm is the sole purchaser of a certain kind of labor. Just as the United States is seeing increasing evidence of monopoly power and cartelization on the producer side, we also need to pay attention to the effects of monopsony power in the labor market.
The classic example of a monopsony is a company coal town, where the coal company acts the sole employer and therefore the sole purchaser of labor in the town. Now why should we care about this? The monopsony power of the coal company allows it to set wages below the productivity of their workers. In other words, employers gain the power to depress wages.
But employers don’t have to be sole employer for monopsonic behavior to arise. If there are a few powerful firms, collusion could drive down wages as well. ...
One of my job market papers -- it was long ago -- assumed monopsony power in labor markets as a way of flipping the correlation between real wages and employment/output from negative to positive (which is more consistent with the empirical evidence starting with Dunlop and Tarshis in the 1930's. For a nice discussion of this evidence, see Keynesian Controversies on Wages, by John Pencavel.