The latest campaign for Wall Street hedge fund Elliott Management is a big one, taking on well-known American staple AT&T. The man in charge of pushing the massive company to make the changes the $38 billion fund sees fit is 39-year-old Jesse Cohn, billionaire Paul Singer's right-hand man. Other than Singer himself, Cohn is the person most responsible for the transformation of Elliott from a distressed situations specialist to the sprawling, institutional behemoth it is today, with a separate private equity arm and billions ready to be deployed for a new activist campaign.