ZIC traders: ZIC stands for Zero Intelligence-Constrained. ZIC traders make stochastic bids and offers that are subject only to a budget constraint (thus the C in ZIC). That is, they are not permitted to engage in trades that result in a negative surplus (trades above a buyer's valuation of a good or below a seller's cost of production). The concept of the ZIC traders originated in ZI traders (Zero Intelligence), which bid stochastically and are allowed to lose money in their trades. It was found that ZI traders do poorly in auction simulations, but that by simply imposing a budget constraint their performance could be significantly improved. In fact, experiments showed that the ZIC algorithm was sufficient to produce almost 100% allocative efficiency in double auctions. These findings imply that market structure is the primary factor in achieving efficiency and equilibrium for continuous double auctions, whereas the cognitive abilities of human traders such as memory, learning, and rationality play only a secondary role. (Gode and Sunder, 1993)