Efficient Market
In welfare economics, a market is efficient when it produces the largest possible total of consumer and producer surplus, known as social surplus.
What is Efficient Market?
At the efficient output, neither consumers nor producers can be made better off without making the other worse off. A competitive market reaches this at equilibrium, but market power, externalities and information problems can prevent it. (In finance, "efficient market" has a different meaning: prices reflect all available information.)