Wiktionary
vendor bid
n. (context finance English) A type of bid at an auction which is made by the auctioneer on behalf of the vendor. This is used as a tactic to keep the bids moving, or to persuade buyers to pay more, or merely to have a higher price to report if the property is pass in (it's not that the vendor wants to buy what he or she is in fact selling). Such a bid is in essence a fiction, but so long as it's clearly announced genuine bidders can know what's going on. When that's not so it approaches the deliberate deception of a dummy bid.