U.K.-based Ruffer Investment Management has managed to quickly turn its recent bitcoin investment into a $750 million profit.

Having bought in November, Ruffer’s investment managers took profits in December and January as the cryptocurrency more than doubled to around $40,000, according to a Telegraph Money report Tuesday.

“We’ve been surprised by how well it has done and how quickly. We did not expect immediate fireworks,” Duncan MacInnes, co-manager of Ruffer Investment told the newspaper.

As CoinDesk reported, the investment firm invested 2.5% of its $27 billion portfolio into bitcoin back in November, making its purchase via One River Digital and Coinbase.

MacInnes said the 2.5% allocation was made across all Ruffer’s funds, costing around $600 million.

As prices soared, the firm opted to take out its original investment and make $650 million in profit. “We still have around $700 million left in and are currently up by $750 million overall,” said MacInnes.

The investor said Ruffer has been following bitcoin for a few years and was previously skeptical of the cryptocurrency. That’s all changed now, however, MacInnes said: “The economic environment for bitcoin right now could not be better.”

Read more: Ruffer Investment Confirms Massive Bitcoin Buy of $744M