A monopoly is the sole producer in an industry. This means industry demand is demand for the
monopoly and that the marginal cost and average cost functions of the monopoly are the
marginal cost and average cost functions for the industry.
Since price is not constant, marginal revenue is not equal to price for a monopolist. Also, since
P is not constant and price is dependent upon the output of the monopoly, a monopoly can
determine commodity price by restricting output.
The marginal cost function of the monopoly is not the supply function for the industry because
quantity supplied is not simply determined by the marginal cost in response to a price but
depends upon the monopolist’s determination of price to maximize profit.
Profit Maximization for a Monopolist: MR = MC
Slope MR= 2*Slope Dor Linear Demand
MR for linear demand has the same intercept term as the Demand function and twice the slope
Elasticity is unit elastic at the midpoint of a Demand function, which means that MR is 0 at the
midpoint because Total Revenue doesn’t change. A monopoly will not produce in the inelastic
portion of a Demand function since a decrease in quantity will a) increase Total Revenue and b)
reduce Variable Costs. The monopolist reduces quantity in the elastic portion of the Demand
function so long as the decreased Variable Cost of one less unit is greater than the decreased
revenue from one less unit, i.e., until MR = MC.
Monopoly Equilibrium and Economic Profit
Monopoly Equilibrium = monopoly output (Q )Mwhere MR = MC
Monopoly Price (P M from Demand at Q M
Average Cost (AC )Mfrom Average Cost at Q M
Economic Profit = (PM- AC M*Q oM P *M - Motal Cost M
Types of Monopoly
1) Government Monopolies: governments perform functions that otherwise might be
monopolized, establish public corporations with monopoly power in an industry, or grant
monopoly power to private firms. The rationale for government monopolies is to prevent private
exploitation of a natural monopoly for revenue purposes.
2) Control of an Essential Input (‘Normal’ monopoly): control over an essential resource,
technology, or product establishes the barrier to entry for most monopolies. Since control over
an input or output eliminates the entry of other firms, the ‘Normal’ need only be large enough to
produce the output that maximizes profit. This means the