Hedge fund titan Steve Cohen is no longer trading stocks. Here’s why it’s an important milestone for the $4 trillion industry.

He’s the inspiration behind “Billions” protagonist Bobby Axelrod and was portrayed by Vincent D’Onofrio in “Dumb Money,” the movie loosely based on the GameStop saga. Among his $1 massive art collection, which was once valued at $1 billion, is a 14-foot shark preserved in formaldehyde. He paid celebrity chef Guy Fieri $100,000 to visit Connecticut mom-and-pop restaurants with him for a day, in a personalized version of Fieri’s long-running Food Network show.

For an industry that’s become more buttoned-up and less personality-driven, Cohen might be the last of his kind — and the overwhelming sentiment from those who have worked with him and competed against him is that this announcement was the end of an era.