In the short run in perfectly competitive markets, a firm may
make negative, zero, or positive economic profits.Market prices get pushed up
or down by changing market conditions in the short run.If market price falls
below the firm's minimum Average Total Cost, the firm runs a loss.If market
price rises above the firm's Average Total Cost at the profit-maximizing output
level, the firm runs a profit,If market price equals Average Total Cost at the
firm's profit-maximizing output level, the firm earns zero profit.
Perfect competitors'short-run profit level