Bill Ackman is a long term value investor, taking advantage of short term downward moves in prices. He is particularly successful at special situations investments. William Ackman’s Pershing Square has a very concentrated portfolio. Bill Ackman’s returns have displayed option-like characteristics in 2009 and 2010. His General Growth Properties investment is almost as big as John Paulson’s subprime shorts. In May 2009, he recommended GGP stock at the Ira Sohn Conference and the stock returned more than 1000% since then. As a result of that investment, Ackman had a great 2010, returning 29.7%. Bill Ackman's Pershing Square lost 1.1% in 2011 but gained 12.4% in 2012, 9.7% in 2013. Bill Ackman is displaying amazing returns so far in 2014. His flagship fund is up 22.1 through the end of May. Bill Ackman's net worth is north of $1.5 billion and Pershing Square had around $12 billion in AUM in early 2014.