Peter Thiel and his venture capital firm, Founders Fund, are big believers in Bitcoin.
The PayPal co-founder and other Founders Fund partners bought $15 million to $20 million worth of the cryptocurrency that’s now worth hundreds of millions of dollars, according to a Wall Street Journal report on Tuesday that cites unnamed sources.
The report didn’t say exactly when Thiel or his VC firm first bought Bitcoin, whose value has fluctuated from record highs to dramatic declines in recent months. The volatility has alarmed some economists, who worry of a bubble.
Thiel and the Founders Fund, however, don’t appear to share those concerns, and are instead pitching Bitcoin to their investors as “a high-risk, high-reward wager similar to its other venture bets,” the report said.
Get Data Sheet, Fortune’s technology newsletter.
Shares of Bitcoin jumped over 13% on Tuesday from $13,412 to $15,216 after the report, according to Coindesk.
In October, Thiel reportedly said during an investment conference in Saudi Arabia that people are “underestimating” Bitcoin and he compared the cryptocurrency to gold.
“If bitcoin ends up being the cyber equivalent of gold it has a great potential left,” he said at the time. About other cryptocurrencies, however, Thiel said he was “skeptical of most of them.”
Other cryptocurrencies include Ripple, Ethereum, and Litecoin.
A Founders Fund spokesperson declined to comment on the report.
