Chapter 9 The Performance of Double Auction and Posted Offer Markets with Advance Production This chapter summarizes the price performance of double auction and posted offer markets generated in 120 laboratory sessions and more than 1800 trading periods. It shows that the mean contract price differences between double auction and posted offer institutions which are common in production to demand markets narrow with production in advance of sale. Furthermore the consideration of inventory carryover in advanceproduction markets results in a further reduction of contract prices. At this point price performance differences between the two trading institutions disappear. The efficiency of the posted offer institution is improved significantly however if sellers are permitted a second price posting in each trading period. Although this is very different from the continuous price posting and contract formation by both buyers and sellers characteristic of the double auction institution it ultimately leads to comparable efficiency levels in both double auction and posted offer markets when production is in advance of sale inventories may be carried from period to period and traders are experienced.