Proxy bid
Encyclopedia
Proxy bidding is an implementation of an English
second-price auction used on eBay
, in which the winning bidder pays the price of the second-highest bid
plus a defined increment. It differs from a Vickrey auction
in that bids are not sealed; the "current highest bid" (defined as second-highest bid plus bid increment) is always displayed. In a standard first-price English auction the winner pays the amount of their bid, regardless of competitors' bids, and it is therefore desirable to place a bid that exceeds the current highest bid by the smallest possible increment. Under proxy bidding, however, the price paid is determined only by competitors' bids and not by the amount of the new bid, and so there is no economically rational incentive to place a bid below the amount one is willing to pay, or to place multiple increasing bids. An "economically rational" bidder will therefore bid the maximum amount they are willing to pay on their first bid, and never raise their bid.
English auction
An English auction is a type of auction, whose most typical form is the "open outcry" auction. The auctioneer opens the auction by announcing a Suggested Opening Bid, a starting price or reserve for the item on sale and then accepts increasingly higher bids from the floor consisting of buyers with...
second-price auction used on eBay
EBay
eBay Inc. is an American internet consumer-to-consumer corporation that manages eBay.com, an online auction and shopping website in which people and businesses buy and sell a broad variety of goods and services worldwide...
, in which the winning bidder pays the price of the second-highest bid
BID
Bid may refer to:*Bidding, making a price offer in an auction, stock exchange, or card games*Bid , a British home shopping channel...
plus a defined increment. It differs from a Vickrey auction
Vickrey auction
A Vickrey auction is a type of sealed-bid auction, where bidders submit written bids without knowing the bid of the other people in the auction, and in which the highest bidder wins, but the price paid is the second-highest bid. The auction was created by William Vickrey...
in that bids are not sealed; the "current highest bid" (defined as second-highest bid plus bid increment) is always displayed. In a standard first-price English auction the winner pays the amount of their bid, regardless of competitors' bids, and it is therefore desirable to place a bid that exceeds the current highest bid by the smallest possible increment. Under proxy bidding, however, the price paid is determined only by competitors' bids and not by the amount of the new bid, and so there is no economically rational incentive to place a bid below the amount one is willing to pay, or to place multiple increasing bids. An "economically rational" bidder will therefore bid the maximum amount they are willing to pay on their first bid, and never raise their bid.