Last month, Christie’s, Sotheby’s and Phillips sold a record $2.7 billion of art. Among the higher-priced works -- those fetching $1.5 million or more -- 13 had changed hands at least once before in the previous three years, according to New York-based Skate’s Art Market Research. That’s an increase of 54 percent from a year ago. In the two weeks of May auctions, 221 works overall sold for more than $1.5 million, Skate's said. In May 2007, the previous art market peak, only four such trades took place, according to Skate’s, which tracks auction results through a database of 10,000 works at prices starting at $1.5 ... (full story)