 The building was once home to one of the world's largest private collections of Mark Rothko works.The former owner—alleged Bernie Madoff middleman and ex-financier J. Ezra Merkin—still lives there, but the paintings were sold during the Madoff scandal.Hedge fund billionaire Charles Stevenson paid $9 million for an apartment in the building and was the head of the 740 Park Avenue cooperative in December 2011.