Bid shading

Abstract: A method of conducting an on-line auction that permits individual bidders to pool bids during a bidding session. The auction is conducted over a computer network that includes a central computer, a number of remote computers, and communication lines connecting the remote computers to the central computer. A number of bidding groups are registered in the central computer, each bidding group having a total bid for the item being auctioned. Bids entered from the remote computers are received in the central computer, each bid including a bid amount and a bid designation. Each bid amount is contributed to the total bid of the bidding group indicated by the bid designation. The bidding group having the largest total bid at the end of the bidding session wins the item being auctioned.

Abstract: This paper examines bidding in auctions for state highway construction contracts on Long Island in the early 1980s, in order to determine whether bid rigging occurred. Detection of collusion is possible because of limited participation in the collusive scheme. The paper looks at differences in behavior between ring members and non-members. In these auctions, collusio did not take the form of a bid rotation scheme, in which only one ring member submits a bid. Instead, several ring members bid on most jobs. The apparent role of ring meetings prior to the auction was to designate a serious bidder, and its bid, and the other firms then frequently submitted phony higher bids. The bidding data indicate that the bids of non-cartel firms, as well as their rank distribution, were related to cost measures, such as how much backlog a firm was carrying. In contrast, the rank distribution of higher cartel bids was unrelated to similar cost measures, and differed from the distribution of the low cartel bid.

Abstract: Auctions often involve the sale of many related goods: Treasury, spectrum, and electricity auctions are examples. In multi-unit auctions, bids for marginal units may affect payments for inframarginal units, giving rise to “demand reduction” and furthermore to incentives for shading bids differently across units. We establish that such differential bid shading results generically in ex post inefficient allocations in the uniform-price and pay-as-bid auctions. We also show that, in general, the efficiency and revenue rankings of the two formats are ambiguous. However, in settings with symmetric bidders, the pay-as-bid auction often outperforms. In particular, with diminishing marginal utility, symmetric information and linearity, it yields greater expected revenues. We explain the rankings through multi-unit effects, which have no counterparts in auctions with unit demands. We attribute the new incentives separately to multi-unit (but constant) marginal utility and to diminishing marginal utility. We also provide comparisons with the Vickrey auction.