Monopoly Capital: An Essay on the American Economic and Social Order is an essay from 1966 by Paul Sweezy and Paul A. Baran. It made a major contribution to Marxist theory by shifting attention from the assumption of a competitive economy to monopolistic aspects of giant corporations that dominate market life.
Big business can maintain selling prices at high levels while still competing to cut costs, advertise and market their products. Competition is generally limited however with a few large capital formations sharing various markets, with the exception of a few actual monopolies (such as the Bell System at the time). The economic surpluses which result cannot be absorbed through consumers spending more. The concentration of the surplus in the hands of the business elite must therefore be geared towards imperialistic and militaristic government tendencies, which is the easiest and surest way to utilise surplus productive capacity.
Exploitation focuses on low wage workers and groups at home, especially minorities. Average earners see the pressures in drive for production destroy their human relationships, leading to wider alienation and hostility. The whole system is largely irrational, since though individuals may make rational decisions, the ultimate systemic goals are not. The system continues to function so long as Keynesian full employment policies are pursued, but there is the continued threat to stability from less-developed countries, throwing off the restraints of neo-colonial domination.