In a number of observed procurements, the buyer has employed an auction format that allows for a split-award outcome. We focus on settings where the range of uncertainty regarding scale economies is large and, depending on cost realizations, the efficient allocations include split-award outcomes...

Collusive equilibria exist in open ascending auctions with multiple objects, if the number of the bidders is sufficiently small relative to the number of objects, even with large complementarities in the buyers' utility function. The bidders collude by dividing the objects among themselves,...