A Comment on ‘Strange Bids: Bidding Behaviour in the United Kingdom's Third Generation Spectrum Auction’ by Tilman Borgers and Christian Dustmann
评论了Borgers和Dustmann关于英国3G拍卖中投标者行为的研究，作者作为BT的顾问，解释了BT在拍卖中对大牌照相对小牌照的支付意愿为何大幅上升，并讨论了简单投标策略在共同价值情境下的局限性。
Had the licences in the UK 3G auction all been identical, there would have been few interesting questions that we could now pose. However, as there were large and small licences, bidders could switch between different types of licence and observe how other bidders switched. By analysing this switching, Borgers and Dustmann have identified certain aspects of bidder behaviour that seem difficult to rationalise. One question they raise is that BT's apparent willingness to pay for a large licence relative to a small licence increased dramatically during the course of the auction. I assisted BT in the course of the UK 3G auction and can hopefully shed some light on this strange behaviour. Paul Klemperer (2002, 2004) has provided a somewhat similar analysis of the auction. The authors take straightforward bidding with private values as their benchmark hypothesis about bidder behaviour. This was also our starting point in formulating a strategy. Where other bidders have fixed valuations that do not change in the course of the auction and follow a straightforward bidding strategy, then straightforward bidding is a best response. Whilst theory clearly allows for many other equilibria, straightforward bidding is an attractive option for bidders in practice; it is simple, reasonably robust against a range of alternative strategies and easy to explain and rationalise to investors ex post. Nevertheless, there were additional considerations arising from common valuations and the presence of large and small licences that suggested that a simple straightforward bidding strategy for BT was not necessarily optimal.