An irrevocable bid is a binding commitment by a third party to buy a specific lot at an auction at or above a fixed minimum price, made before the sale begins. The arrangement underwrites the lot for the consignor: regardless of what happens in the saleroom, the lot will sell for at least the agreed minimum, and the consignor receives that price net of fees. The mechanism is widely used at the high end of fine art, jewellery, and gem auctions at Sotheby's, Christie's, Phillips, and Bonhams, and has reshaped the economics of major lots over the past two decades.

How the arrangement works

The auction house identifies a lot of sufficient value or sensitivity that a guaranteed sale is desirable, and approaches one or more potential bidders with a proposal. The third party, often a major collector, dealer, or institution, agrees in writing to bid the lot up to a confidential reserve and to buy it at that level if no one else does. The auction house then markets the lot in the normal way, and the irrevocable bidder participates in the saleroom or by phone bidding alongside other buyers.

If a higher bid is received, the irrevocable bidder may continue bidding or may drop out, in which case the lot sells to the higher bidder at the hammer price. In that scenario, the irrevocable bidder typically receives a financing fee, a share of the upside above the agreed minimum, or both. If no other bid is received above the minimum, the lot is hammered down to the irrevocable bidder, who pays the agreed price.

Disclosure

Major auction houses are required by salesroom regulation, in particular New York's Rule 23-700 and Department of Consumer Affairs licensing rules, to disclose in printed and online catalogues which lots are subject to a third-party guarantee or irrevocable bid. The catalogue typically marks such lots with a symbol explained on the disclosure page, and the auctioneer announces the existence of an interest before bidding opens. UK auction-house regulation imposes broadly similar disclosure obligations through the British Art Market Federation code and the Consumer Protection from Unfair Trading Regulations.

Disclosure does not, however, identify the irrevocable bidder. The identity remains confidential between the bidder and the house, and the bidder typically conducts saleroom bidding through a paddle or telephone like any other buyer.

Use in jewellery and gem auctions

Major coloured stone, signed jewellery, and important diamond lots are routinely placed under irrevocable bid at the top auction houses. The Wittelsbach-Graff blue diamond, the Princie pink diamond, the Pink Star, and the Oppenheimer Blue have all been backed by guarantees or third-party irrevocable bids in their successive auction sales. The arrangement gives consignors of significant gem lots assurance that the years-long preparation of a single-lot sale will result in a transaction at a defensible level, and it gives the auction house a reduced risk profile in marketing the lot.

Trade considerations

For an aspiring buyer, the existence of an irrevocable bid on a lot affects the bidding dynamic. The minimum sale price is anchored at the agreed level, so the lot will not sell below it, and the irrevocable bidder is committed to buying at that price unless someone else outbids them. Bidders who push above the minimum will need to continue past the irrevocable bidder's appetite to win the lot. The disclosure of an irrevocable bid in the catalogue is therefore a real piece of information, and serious buyers read the disclosure pages alongside the lot descriptions when planning saleroom strategy.