An Italian cryptocurrency exchange called BitGrail said on Friday that it lost about 17 million tokens of a cryptocurrency called Nano, with a market value of about $170 million.

In a note on its website, the exchange said “internal checks revealed unauthorized transactions which led to a 17 million Nano shortfall, an amount forming part of the wallet managed by BitGrail.” It didn’t indicate exactly when the hack occurred.

The exchange said that it has informed authorities, and that it didn’t believe any other currencies it holds were affected. It did say, however, that it was suspending all withdrawals and deposits temporarily. A representative of BitGrail couldn’t be reached Friday evening in New York.

But a person with the Twitter username “Francesco the Bomber,” who appears to run the exchange, made several comments on the social-media site following the announcement. “We are transparent, funds are stolen,” said one. Another said “there is an ongoing investigation by police.”

The person posting also said that the exchange couldn’t pay its customers back. He also referenced “unfounded allegations” being made against him.


It was the second large hack of a cryptocurrency exchange this year. In January, Tokyo-based Coincheck reported that hackers vaulted its security measures and stole about $530 million worth of customer assets.

The firm said it would compensate those customers. In December, a South Korean exchange called Youbit shut down after its second hack in less than a year, and another exchange called NiceHash lost more than $70 million worth of bitcoin to hackers.

The most infamous hack in this sector was the $460 million theft from Japanese exchange Mt. Gox in 2014. While other famous hacks, like Equifax or the U.S. Office of Personnel Management, usually involve data, cryptocurrencies offer a very tempting target to hackers. Because they are designed to have inalterable histories, transactions in bitcoin and other cryptocurrencies can’t be erased. That means once a hacker moves bitcoin from a target’s online wallet to their own, it’s hard to get it back.

The price of a nano fell 6.5% to $10.21, according to coinmarketcap. Nano is a thinly traded currency, with only about $53 million changing hands daily. It trades on only about a dozen exchanges, including BitGrail.


The hack didn’t affect the prices of other cryptocurrencies. Bitcoin was up 11% at $9,001, Ethereum was up 12% at $902.

Nano was by far BitGrail’s largest currency by volume, with $2.7 million worth of bitcoin traded. The exchange handles trades for eight different cryptocurrencies.

Nano is a newer cryptocurrency, which launched in 2015 under the name raiblocks. The development team just last week announced it was rebranding the token. On Dec. 1 the currency, then called raiblocks, was trading at 20 cents. It surged to a high of $37.62 on Jan. 2, before dipping below $7 on Feb. 6, according to coinmarketcap.

Corrections & Amplifications

The cryptocurrency nano trades on only about a dozen exchanges, including BitGrail. An earlier version of this article incorrectly stated the cryptocurrency nano didn’t trade on major digital exchanges.


Write to Paul Vigna at paul.vigna@wsj.com