n. The practice of placing a low bid in an online auction, having a second person enter a bid that is high enough to discourage other bidders, and then withdrawing that high bid just before the auction closes.
Bid shielding is an unethical practice of trying to block others from bidding. Here's how it works: One person bids $10 for a book and a colleague quickly bids $500, assuming that no one will overbid the inflated price. The high bidder retracts the bid at the last minute, giving the first person a $10 deal.
While online bidders have long worried whether the item they're buying will arrive in the promised condition — and sellers have wondered about being paid — these days they may also have to contend with "sniping," "bid shielding" and other bid manipulations.
Other problems can arise from bid shielding, where a bidder and an associate make artificially high bids to discourage others from bidding, with the associate then dropping out to allow the bidder to win the auction with a lower offer.