Mark Rothko, 1961. Three luminous horizontal rectangles. Sold for $86.9M in 2012.
From Wikipedia
Orange, Red, Yellow is a 1961 Color Field painting by Mark Rothko. On May 8, 2012, it was sold at Christie's from the estate of David Pincus for $86,882,500, a record nominal price for post-war contemporary art at public auction.