Bitcoin surpassed $10,000 for the first time, bringing this year’s price surge to more than 10-fold even as warnings multiply that the largest digital currency is an asset bubble.

The euphoria is bringing to the mainstream what was once considered the providence of computer developers, futurists and libertarians seeking to create an alternative to central bank-controlled monetary systems. While the actual volume of transactions conducted in cryptocurrencies is relatively small, the optimism surrounding the technology continues to drive it to new highs.

Bitcoin has risen by more than 50 percent since October alone, taking off after developers agreed to cancel a technology update that threatened to split the digital currency. Even as analysts disagree on whether the largest cryptocurrency by market capitalization is truly an asset, its $167 billion value already exceeds that of about 95 percent of the S&P 500 Index members.

“This is a bubble and there is a lot of froth. This is going to be the biggest bubble of our lifetimes,” hedge fund manager Mike Novogratz said at a cryptocurrency conference Tuesday in New York.

Novogratz, who’s says he began investing in bitcoin when it was at $90, is starting a $500 million fund because of the potential for the technology to eventually transform financial markets.

There’s no agreed authority for the price of bitcoin, and quotes can vary significantly across exchanges. In Zimbabwe, where there’s a lack of confidence in the local financial system, the cryptocurrency has traded at a persistent premium over $10,000. Volumes are also difficult to assess. Bloomberg publishes a price that draws on several large bitcoin trading venues.

From Wall Street executives to venture capitalists, observers have been weighing in, with some more skeptical than others as bitcoin’s rise has grown steeper, sweeping along individual investors. The number of accounts at Coinbase, one of the largest platforms for trading bitcoin and rival ethereum, has almost tripled to 13 million in the past year, according to Bespoke Investment Group LLC.

In a move toward mainstream investing, CME Group Inc. has said it plans to start offering futures contracts for bitcoin, which could begin trading in December. JPMorgan Chase & Co., the largest U.S. bank, was weighing last week whether to help clients bet on bitcoin via the proposed futures contracts, according to a person with knowledge of the situation.

“A sustained move above $10,000 will indicated people’s faith that further appreciations is expected,” Swissquote Bank SA head of market strategy Peter Rosenstreich said before the benchmark was reached. “Otherwise we should see significant profit-taking and decline as people sell.”

The total market cap of digital currencies now sits north of $300 billion, according to data on Coinmarketcap.com’s website.

Rosenstreich at online trading firm Swissquote said bitcoin’s surge harks to the surprises of the U.K. referendum on European Union membership and President Trump’s election.

“We have underestimated the populist movements,” he said. “There is growing unease on how central banks and governments are managing fiat currencies. Ordinary people globally understand why a decentralized asset is the ultimate safe haven.”