Sotheby’s has canceled this week’s scheduled auction in London of Russian artwork collected by the late cellist Mstislav Rostropovich and his wife, soprano Galina Vishnevskaya, after a buyer bought all 450 lots for more than $40 million this weekend, reports Bloomberg.

Sotheby’s has not released the name of the buyer, but there are reports that it’s the Russian billionaire Alisher Usmanov. The auction house did say that the buyer is expected to take the collection to Russia.