The billionaire investor said in a Tuesday webcast: "Of course retail investor activity is downright terrifying. ": Hedge fund billionaire Jeffrey Gundlach is sounding the alarm on a "downright terrifying" boom in day-trading and retail investor activity. The so-called "bond king" and founder of DoubleLine Capital, was quoted by CNBC in a webcast Tuesday as saying: "of course, retail investor activity is downright terrifying." He said an increase in trades-per-account on online brokerage platforms was worrying. "We just see how much trading is going on in retail," Gundlach said.