Venture capitalist Peter Thiel is placing a new bet in the crypto space. The early Facebook investor was a part of Cayman Islands start-up Block.one’s most recent funding round announced Monday.

The company recently raised a record $4 billion to fund its blockchain platform EOSIO through a process known as an initial coin offering, or ICO. The fundraising more than doubled the next biggest offering of that type, and eclipsed the world’s biggest initial public offerings on stock exchanges this year before its flagship product even went live.

“As Block.one prepares to announce its future plans, we’re excited to welcome key strategic investors aligned with our values of creating a more secure and connected world,” Block.one CEO Brendan Blumer said in a press release. The company did not give a dollar amount in the announcement.

Well-known Chinese start-up Bitmain, which dominates the bitcoin “mining” industry, also participated in the funding round. According to a recent Bernstein analysis, the company likely made $3 billion to $4 billion in operating profit in 2017, as much as chipmaker Nvidia did in the same year.

Thiel co-founded PayPal in 1998, was one of the first outside investors in Facebook. Founders Fund, the venture-capital firm he co-founded, began amassing hundreds of millions of dollars in cryptocurrency including bitcoin in 2017, the Wall Street Journal reported in January, citing people familiar with the matter. In March, Thiel said he was “long bitcoin” and highlighted its possibility of becoming a gold-like safe-haven investment. The billionaire backed the idea of bitcoin becoming a store of value instead of a go-to currency for daily transactions.

Bitcoin prices have struggled since. The cryptocurrency has fallen by more than 50 percent this year, after climbing to almost $20,000 in December.

Block.one, was featured in a March episode of HBO’s “Last Week Tonight,” where host John Oliver warned viewers about the “speculative mania” and risks of investing in cryptocurrency.

“It can be incredibly hard to tell which companies are for real,” Oliver said during the episode, which has 5.98 million views on YouTube. “If you want a good example of this, look at Block.one, which has raised $1.5 billion.”

Oliver listed a number of concerns: An apparent lack of seriousness by advisor and noted early bitcoin investor Brock Pierce, the exponential pace of fundraising relative to established tech giants such as Facebook, and a Wall Street Journal report calling Block.one “a software startup that doesn’t plan to sell any software.”

The cryptocurrency eos is now the fifth biggest by market capitalization, worth roughly total $7.2 billion, according to data from CoinMarketCap.com. It has fared better than most cryptocurrencies this year, down only 8 percent year to date in what has been a volatile bear market. Eos was up about 10 percent as of Thursday evening, according to CoinMarketCap.com.

The system, according to its founders, will support more efficient operations for “decentralized applications” than existing platforms such as ethereum. If EOSIO is successful, advocates say it could bring on much greater adoption of cryptocurrency-related technology.