Coinbase, one of the world's largest cryptocurrency exchanges, brought in a fortune last year thanks to the exploding popularity of digital coins.

Industry sources told Recode that the six-year-old San Francisco-based company raked in $1 billion in revenue in 2017, enough to suggest that the bitcoin trading broker was the go-to platform for the scores of investors who bought and sold cryptocurrencies during the year.

Coinbase, which makes money from trading volumes, expected to generate just $600 million in annual sales at the end of September. However, soaring interest in bitcoin and other virtual currencies between Thanksgiving and Christmas saw demand for its service skyrocket toward the end of the year. (See also: Cryptocurrency Hedge Funds Gained More Than 1,000% In 2017.)

Since November, cryptocurrency trading volumes have reportedly held steady above $25 billion a day, according to Business Insider. Coinbase, which charges buyers and sellers a fee of between 0.25 percent and 1 percent to trade virtual currencies, emerged as a key beneficiary of the rising demand for digital coin investments.

Business Insider previously claimed that Coinbase added 100,000 users in just three days over the Thanksgiving holiday. Appetite to buy and sell cryptocurrencies was said to be so high during the period that some of Coinbase’s rival exchanges were forced to stop welcoming new customers. Others, such as Kraken, reportedly added around 50,000 new users a day at the end of 2017.

Coinbase has been using some of its newfound fortune to recruit experienced staff. Explosive user growth has made hiring fresh faces imperative as the company seeks to tackle complaints about outages and slow customer service response times. (See also: Should You Leave Coinbase? Some Bitcoiners Say Yes.)

On Monday, Coinbase continued its recruitment drive by bringing in Twitter executive Tina Bhatnagar as its new vice president of operations and technology. Bhatnagar helped Twitter’s customer service team to handle rapid user growth during her five and a half year tenure.

“Not only did [Bhatnager have] the depth of experience, but also the right temperament: assertive enough to take control, while patient and empathetic to our customers’ plights,” said Coinbase CEO Brian Armstrong in a blog post announcing the hire.

Coinbase has made a habit of hiring staff from big tech firms. Late last year, the company appointed Asiff Hirji, a former top executive at Hewlett-Packard and TD Ameritrade, as its new president and COO and David Marcus, vice president of messaging products at Facebook and a former president of PayPal, to its board.

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