Bitcoin exchange Coinbase Inc. is believed to have booked $1 billion in revenue in 2017, arguably justifying the faith of investors who made it the first “bitcoin unicorn” back in August.

Recode, quoting “industry sources,” makes the claim in a report that also suggests that as recently as September, the company only expected to book $600 million in revenue for the year. But that figure apparently surged thanks to last year’s bitcoin mania.

As a result, the report said, Coinbase’s value likely doubled since its $100 million fundraising in August, which was on a $1.6 billion valuation. That made it a unicorn, or startup worth more than $1 billion.

What’s more, according to the report, wannabe investors are desperately trying to buy private stock in the company. Venture capitalists and brokers are asking existing investors whether they would consider selling their Coinbase shares, which the company doesn’t allow. Investors in Coinbase include Institutional Ventures Partners, Spark Capital, Greylock Partners, Battery Ventures, Section 32 and Draper Associates.

“As a private company, Coinbase does not allow trading of stock on secondary markets for a variety of reasons, including the fact that there is not full and equal information available to the market,” the company said in a statement. “We will take appropriate action if we find people have sold Coinbase shares in violation of our agreements not to do so.”

Although Coinbase has thrived as cryptocurrency trading has become more mainstream, the company is not without problems. Along with an ongoing dispute with the Internal Revenue Service over customer data disclosure, employees at the company were alleged to have been involved in insider trading of Bitcoin Cash, a bitcoin alternative, when it launched Dec. 19.

To its credit, Coinbase did launch an investigation into the insider trading allegations, although just over a month later the company has not yet disclosed results of the probe.

Coinbase has also suffered growing pains as it rapidly increased its user base, resulting in multiple downtime incidents in December.

Image: Coinbase