The Christie’s website has been shut down by hackers just days before three marquee sales are expected to bring in around $840 million.

As of May 10, a message shared on a page redirected from the auction house’s website reads: “Important Information: We apologize that our website is currently offline. We are working to resolve this as soon as possible and regret any inconvenience. To register your interest, or to bid, in an upcoming sale please use the contact details provided.”

The hack was first reported by the New York Times, citing a confirmation from spokesman Edward Lewine.

“We are taking all necessary steps to manage this matter, with the engagement of a team of additional technology experts,” he said in a statement. “We will provide further updates to our clients as appropriate.”

A screenshot shows the Christie’s website as of May 10. Photo: Screen grab.

According to the Times, some collectors and art advisers first noticed the problem on Thursday evening. That it was still out by Friday afternoon could pose challenges for the auction house ahead of next week’s sales. It was not immediately clear if the hackers had gained access to any sensitive information held by the company.

Last September, a data breach at Christie’s affected photographs of paintings and sculptures that collectors had uploaded to the site for review by the auction house. According to the cybersecurity company that unearthed the breach, about 10 percent of the images contained GPS coordinates pointing to the location of the artworks.

Christie’s big week is slated to begin with the May 14 sale of the Rosa de la Cruz collection, which is expected to achieve more than $30 million in sales, the auction house said.

The 21st Century Evening Sale, also on May 14, is expected to earn more than $100 million. That sale is anchored by Brice Marden’s Event (2004–7) with a high estimate of $50 million and Jean-Michel Basquiat’s The Italian Version Of Popeye Has No Pork In His Diet (1982) with an estimate in excess of $30 million.

The 20th Century Evening Sale, two days later, is expected to earn up to a high estimate of $500 million, featuring artists including Andy Warhol, Pablo Picasso, Alberto Giacometti, Georgia O’Keeffe, David Hockney, and Rene Magritte—though the top lot of the sale is Vincent van Gogh’s Coin de jardin avec papillons (1887), expected to realize up to $35 million.