There was a contract between the auction house and the artist.
However that’s not strictly required: “Wrongful interference in a business relationship occurs when there is no contract. The defendant attempts to disrupt the relationship, causing economic harm. If the defendant defames the business owner’s product, resulting in loss of business, that is tortious interference in the business.”
However that’s not strictly required: “Wrongful interference in a business relationship occurs when there is no contract. The defendant attempts to disrupt the relationship, causing economic harm. If the defendant defames the business owner’s product, resulting in loss of business, that is tortious interference in the business.”
https://www.findlaw.com/smallbusiness/liability-and-insuranc...