Clearly, Billions is grounded in reality — that's what makes it a show that people in the industry enjoy so much, too. According to Damian Lewis' interview with Page Six, Wall Streeters frequently ask him if Bobby is based on billionaire and hedge fund manager Bill Ackman (they share the same initials). In Season 1 of Billions, Bobby gets in a fight with a rival investor that resembles Ackman's feud with Carl Icahn . Though Lewis maintained that Bobby isn't based on a single person, that doesn't mean people won't keep guessing. For insiders plugged into the world of Wall Street, Billions is an entertaining (and accurate) parade of allusions.