The competitive market model is a paradoxical. In perfect competition, agents cannot influence price: they only select an output quantity. Such passive behavior doesn’t conform to the intuitive notion of competition. This paper describes an experiment which demonstrates that near or even at a competitive equilibrium price, competition is undiminished. A substantial difference between the performance of sellers and buyers frequently results from this vigorous competition, even with low price variability and approximate efficiency. In double auction experiment sessions conducted with both automated and human agents, exogenous variation of the pace of asks and bids of automated agents demonstrates that the performance difference between sellers and buyers results primarily from a difference between the pace of asks and bids. If the buyers’ pace is slower than sellers’ pace, buyers make price concessions less frequently than sellers so that prices move below the equilibrium price. Then more buyers become active and fewer sellers remain active. Prices stabilize when changes to the numbers of active buyers and sellers offset the superior bargaining capability of one side or the other. In competitive equilibrium, to a first approximation agents are price takers, but that doesn’t preclude vigorous competition: competitive behavior moves to the dimension of bargaining pace.
