"Black Square", the fourth version of his magnum opus painted in the 1920s, was discovered in 1993 in Samara and purchased by Inkombank for US$250,000. In April 2002, the painting was auctioned for an equivalent of US$1 million. The purchase was financed by the Russian philanthropist Vladimir Potanin, who donated funds to the Russian Ministry of Culture, and ultimately, to the State Hermitage Museum collection. According to the Hermitage website, this was the largest private contribution to state art museums since the October Revolution.