A major hack suffered by Bitfinex, one of the world's most popular cryptocurrency exchanges, led to a 20% drop in the value of Bitcoin. One Bitcoin currently buys $538 and €482.
While an official total has not been released by the site - TechCrunch reports that staff members have confirmed that 119,756 bitcoins have been stolen. These coins were worth some $65m (€58m).
While the blockchain technology which tracks and secures Bitcoin transfers could lead to a massive reduction in the cost of electronically transferring money - safety concerns have been a thorn in the side of the currency.
The site has not offered details regarding how the attack was carried out - other than confirming that funds had been lost and that it has suspended trading.
Its statement added: "The theft is being reported to - and we are co-operating with - law enforcement."
"We know that some of our users have had their bitcoins stolen," the Hong Kong-based company confirmed.
The site worked with BitGo, a bitcoin security company which allows users to closely monitor their balances in a number of wallets. Wallets act like online accounts to hold Bitcoins.
The mass-selling of Bitcoins is reflective of an increase in fear over the security of the currency.
In June DAO, another Bitcoin service, reported theft of a similar size. In 2014 Tokyo's Mt. Gox collapsed after Bitcoins worth $450m were stolen.
