He would fire an employee trading bitcoin for being "stupid," says JPMorgan Chase chief executive Jamie Dimon.
The cryptocurrency "won't end well," Dimon told an investor conference in New York, predicting it will eventually blow up. "It's a fraud" and "worse than tulip bulbs."
So if a JPMorgan trader was dealing in bitcoin "I'd fire them in a second. For two reasons: It's against our rules, and they're stupid.
"And both are dangerous."
Bitcoin has soared recently, spurred by greater acceptance of the blockchain technology that underpins the exchange method and optimism that faster transaction times will encourage broader use of the cryptocurrency.
Prices have climbed more than four- fold this year - a run that has drawn debate on whether it is a bubble.