What is shill bidding?

How shill bidding works

eBay auctions use proxy bidding: you enter the most you’ll pay, and eBay bids for you, one increment at a time, only as far as needed to keep you in the lead. The winner pays one increment over the second-highest maximum, not their own maximum.

That gap between the price and your maximum is what a shill bidder goes after. Say you’re willing to pay $80 for a card and the bidding stands at $40. A second account linked to the seller bids $45, then $50, then $55, each time triggering your automatic bid one step higher, until it nears your maximum and stops. You still win, but at $76 instead of $41. The shill never meant to win; it found your ceiling.

If the shill overshoots and ends up winning, the seller doesn’t sell to themselves. Typical traces: the high bid is retracted, or the item is relisted a few days later, or the next bidder gets a Second Chance Offer.

Is shill bidding illegal?

Shill bidding is against eBay’s rules and, in the US, can be against the law. This is general information, not legal advice.

• Auction law. Section 2-328 of the Uniform Commercial Code, adopted in every state but Louisiana, says that when a seller bids, or has someone bid for them, without disclosing it, the buyer may void the sale or take the goods at the last good-faith bid. California’s version is Commercial Code section 2328.
• Criminal cases. Federal prosecutors have charged eBay shill bidding as mail and wire fraud. The first case, in Sacramento in 2001, involved more than 40 fake accounts and ended in guilty pleas and restitution.
• eBay policy. eBay bans bidding by the seller or by anyone with knowledge of the seller that raises the price or desirability of an item. Sellers can be permanently suspended, even for a first offence.

How to spot shill bidding on eBay

You can’t see who is behind a masked bidder. You can see patterns, and experienced buyers already check them by hand. The strongest live on each bidder’s detail page, which you reach by tapping a masked name in the bid history.

• Bids concentrated with this seller: A bidder whose recent bidding is almost all on this one seller’s items.
• Bid retractions: Bids taken back, especially by a bidder who was leading at the time.
• Small consecutive bids under the leader: Three or more small bids in a row that each fall just short of the leader’s maximum.

Some patterns only show up across many of a store’s auctions:

• Same bidder across the store’s auctions: The same masked bidder appearing in many of one store’s auctions.
• Pushes prices up but rarely wins: A bidder active in many of one store’s auctions who never wins any.
• Relisted soon after “selling”: An item that sold at auction reappearing for sale within two weeks.
• Final price above comparable sales: Auctions that end well above what comparable items sell for.

Susbid checks the single-listing signs for you from a screenshot of the bid history. It shows which are present and the evidence, and leaves the conclusion to you.

What isn’t shill bidding

Plenty of bidding that looks odd is perfectly ordinary:

• Proxy bidding. Your maximum bid jumping up automatically when someone bids is eBay working as designed.
• Sniping. Bids landing in the final seconds are usually other buyers using sniping tools.
• Zero-feedback bidders. Buyers often don’t receive feedback, so new and low-feedback accounts are common among genuine bidders.
• Bidding in small steps. Many cautious bidders raise one increment at a time.
• Loyal customers. Collectors often follow one seller who lists exactly what they collect.

That’s why every sign Susbid reports sits beside its innocent explanations.

What to do if you’re worried

1. Decide what the item is worth to you, and set a maximum bid you’d be happy to pay. Shill bidding only costs you money above that.
2. Check the bid history and the most active bidders’ detail pages, or run a check.
3. If you think it’s happening, report it to eBay: only eBay can see the accounts behind masked names. See eBay’s shill bidding policy.
4. Avoid naming sellers publicly. Patterns have innocent explanations, and eBay is the one that can check.

Common questions