A surge in bitcoin trades in recent weeks has also left the blockchain network that the cryptocurrency relies on to process and verify transactions struggling to keep up. We are constantly improving our systems to ensure that we re able to both accommodate the immense volume of trading that occurs on our platform while also fending off sustained DDoS attacks, he said. On the whole, they buy the cryptocurrency as a speculative investment, attracted by massive price gains, said Garrick Hileman, a research fellow at the University of Cambridge s Judge Business School. S dollar, for example, are extremely rare. authorities shut down the website of the BTC-e exchange, saying it had facilitated transactions involving ransomware, computer hacking, identity theft, tax refund fraud schemes, public corruption, and drug trafficking. 9 billion ($US100 billion) for the first time in its history. 10 and CME Group Inc will launch a rival contract a week later. Some bitcoin watchers, such as Swanson, also worry about the risk of one of the big exchanges being suddenly shut by authorities.