1 Ascending Prices and Package Bidding: Further Experimental Analysis*

We explore the performance of multi-round, price-guided combinatorial auctions for a previously untested class of auction profiles; one with synergies resulting from shared fixed costs. These new profiles indicate the importance of prior information in the form of bidders ’ “names ” (corresponding to packages holding positive value for them) in influencing auction efficiency. The experiments also reveal a new and surprising finding about aggressive bidding tactics by local bidders who bid on valueless items driving up another bidder’s payments, thereby mitigating the “threshold ” problem. Comparisons between a combinatorial clock auction (CCA) and a simultaneous ascending auction (SAA) are reported. Key words: Package auctions, SAA auctions, CCA auctions, threshold problem