In a marketplace, offers are processed that are intended to be associated with other offers in a pool. The offers specify conditions for acceptance. Improvable offers are received that are capable of being associated with offers having more favorable specifications than initial offers associated with the improvable offers. Nonimprovable offers that have more favorable specifications than initial offers associated with improvable offers are identified. The identified nonimprovable offers are associated with corresponding improvable offers. Straddles, which comprise a set of offers and a limit on the associations, may span multiple pools. Information about the marketplace may be obtained from data generated by the operation of the marketplace.