We compare two commonly used mechanisms in public procurement: auctions and negotiations. The execution of the procurement mechanism is delegated to an agent of the buyer. The agent has private information about the buyer's preferences and may collude with one of the sellers. We provide a general characterization of both mechanisms based on public scrutiny requirements and show—contrary to conventional wisdom—that an intransparent negotiation always yields higher social surplus than a transparent auction. Moreover, there exists a lower bound on the number of sellers such that the negotiation also generates a higher buyer surplus.

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Die Dis cus si on Pape rs die nen einer mög lichst schnel len Ver brei tung von neue ren For schungs arbei ten des ZEW. Die Bei trä ge lie gen in allei ni ger Ver ant wor tung der Auto ren und stel len nicht not wen di ger wei se die Mei nung des ZEW dar.Dis cus si on Papers are inten ded to make results of ZEW research prompt ly avai la ble to other eco no mists in order to encou ra ge dis cus si on and sug gesti ons for revi si ons. The aut hors are sole ly respon si ble for the con tents which do not neces sa ri ly repre sent the opi ni on of the ZEW. CONTRACT (RE-)NEGOTIATION WITH PRIVATE AND COMMON VALUES VITALI GRETSCHKO AND ACHIM WAMBACH ZEW MANNHEIM AND UNIVERSITY OF MANNHEIMAbstract. We analyze the contracting problem of a principal who faces an agent with private information and cannot commit to not renegotiating a chosen contract. We model this by allowing the principal to propose new contracts any number of times after observing the contract choice of the agent. We propose a characterization of renegotiation-proof states of this (re-)negotiation and show that those states are supported by a perfect Bayesian equilibrium of an infinite horizon game. The characterization of renegotiation-proof states provides a tool, which is both powerful and simple to use, for finding such states in specific environments. We proceed by applying the results to adverse selection environments with private and common values. We show that with private values and common values of the 'Spence' type only, fully efficient and separating states can be renegotiation-proof. With common values of the "Rothschild-Stiglitz" type inefficient and (partial) pooling states may be renegotiation-proof.JEL classification: C73, C78, D82

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Standard-Nutzungsbedingungen:Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden.Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen.Sofern die Verfasser die Dokumente unter Open-Content-Lizenzen (insbesondere CC-Lizenzen) zur Verfügung gestellt haben sollten, gelten abweichend von diesen Nutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte. Terms of use: Documents in AbstractGermany was the first country in Europe that auctioned off spectrum in the valuable 700 MHz band for mobile telecommunication usage. The German regulator decided to auction off this spectrum together with spectrum in the 900 MHz and 1800 MHz legacy bands. With only the three incumbent operators bidding in the auction and a relatively transparent auction design, it was possible to get a very clear impression of the actual bidding behaviour. We show that in the beginning of the auction, bidders were actively searching for a way to allocate the available spectrum that all bidders could agree to at low prices. Bidders were teaching each other what they should bid and were providing carrots and sticks. When the excess demand was concentrated in one band only, bidders started to compete head on leading to a war of attrition. This competition only stopped when bidders started to raise prices in bands that were already cleared. We interpret this bidding behavior in terms of bidders expressing allocative externalities and conclude that the ability to do so may be regarded as a positive aspect of the transparent design.