Cryptocurrency Bitcoin has just reached its most expensive levels ever thanks to the world's richest man.
Elon Musk's Tesla car company has invested US$1.5 billion in Bitcoin and plans to accept it as payment.
It's seen by some as a vote of confidence in the volatile currency.
When a man worth US$140b - with a Twitter following of 45 million says something it moves the market. And Musk said two things - Tesla was investing US$1.5b in Bitcoin.
"And second, that they intend to start accepting Bitcoin for payment when they sell Tesla cars in the future," says Richard Lyons, Professor of Economics and Finance at the Haas School of Business.
It's brilliant for Bitcoin investors.
"I mean, not surprisingly, when Elon Musk announced that he has put a portion of his treasury, $1.5b into Bitcoin, the price spiked," Bitcoin trader Michael Venuto says.
It's now hit a record high - $45,000 - up 300 percent on this time last year.
Just as exciting for the Bitcoin crowd is Musk accepting Bitcoin for cars - they say it normalises digital currencies.
"I think that not just with Bitcoin, but other cryptocurrencies, stable coins, tether, things like that, that those will become transactional currencies increasingly over the next five years. It's not going to happen overnight," Prof Lyons says.
The cult of Musk has moved other markets. His tweets about a joke cryptocurrency DogeCoin saw its value jump 50 percent and his tweets about shares in the company GameStop had a similar effect.
But there's always a but. Our authorities and other financial experts warn cryptocurrencies are very volatile.
"My own recommendation to the individual investor that's investing a retirement account or something very serious is don't do it," Prof Lyons says.
And there's one small irony - the man who makes electric cars to help save the planet is investing in a digital currency that uses more power in a year than the entire country of Switzerland.
Still he is putting $100 million into carbon dioxide removal technology, a way perhaps to clear his carbon conscience.
