Sotheby 's is the world 's fourth oldest auction house in continuous operation , and the world 's largest art business with global sales in 2011 totaling $ 5.8 billion .
Sotheby 's is the world 's fourth oldest auction house in continuous operation , with 90 locations in 40 countries . 
 It is the world 's largest art business with global sales in 2011 totaling $ 5.8 billion .