In a related development, Rybolovev sued Sotheby's for $380 million in damages for this alleged collusion with Yves Bouvier in 2018, claiming the company "materially assisted the largest art fraud in history", due to Sotheby's vice chairman of private sales worldwide writing "bullish assessments, which Bouvier forwarded to Rybolovlev’s team, about some of the same artworks that Bouvier bought privately through Sotheby’s and flipped to the Russian at higher prices." Rybolovlev alleged that Yves Bouvier defrauded him out of $1 billion through this practice, over several years. Sotheby's dismissed these allegations as "entirely without merit" and stated it would seek to have the case thrown out.