ACM imposes fine on auction website for pushing up prices using automatic bids

The Netherlands Authority for Consumers and Markets (ACM) has imposed a fine on the company behind Dutch auction website Ticketveiling.nl. The company misled consumers by bidding along in auctions using a specially designed algorithm. Auction participants believed that they were bidding against other human bidders. In reality, they were bidding against a bidding bot, which placed bids under different names in order to raise the price unlawfully. In addition, consumers were misled about how the prices of auctioned lots came about. ACM considers these practices to be serious violations, and has therefore imposed a fine of 270,000 euros on House of Tickets B.V., which is the company behind the website.

Martijn Ridderbos, Member of the Board of ACM, explains: “At auctions, prices are determined as a result of supply and demand. Consumers must be able to rely on the fact that this happens in an honest manner. By using a bidding bot, the company behind Ticketveiling consciously disrupted this process. This harms the confidence people have in the online world.”

What was this case about?

On the online platform Ticketveiling.nl, individuals could bid in auctions on excursions, services, and products. In order to be able to ensure a minimum price for the auctioned lots, an algorithm was used, which took part in the auction under different names and using different bidding strategies. This so-called ‘bidding bot’ was used between August 1, 2024, and December 1, 2024, when over 70,000 lots were auctioned. As a result, auction participants believed they were bidding against other human bidders. In reality, they were bidding against a bidding bot used by the company itself. If the bidding bot had won the auction, the human bidders would subsequently still be able to accept the offer at that winning price. In that context, it was not disclosed that the bidding bot had won the auction. In this way, consumers were misled.

Fine for online deception with bidding bots

Due to the use of bidding bots in auctions, thousands of consumers accepted a misleading offer. They might not have agreed to this if they had had the correct information. With these practices, House of Tickets deliberately put its own commercial interests above those of consumers. The company has acknowledged the violations, and has ended them of its own accord, prior to ACM’s investigation. In addition, it has announced that it accepts the fine. In doing so, the company also waives any objections and appeals. For cooperating with this simplified procedure, the company received a discount of ten percent on the fine, resulting in a total of 270,000 euros.

Over the next few months, ACM will remain alert to the use of algorithms, so that consumers can participate in digital markets with confidence.

See also

28-05-2026 ACM imposes fine on House of Tickets for misleading practices in online auctions (in Dutch)