Coincheck, a digital currency exchange based in Japan, has restricted trading in NEM\'s XEM coin, following reports that deposits weren\'t showing up in users\' accounts.

The exchange firstly advised users not to make any XEM deposits in their accounts, and subsequently asked them to cease trading XEM altogether. This was around midday in Japan on January 26th, and minutes later a further warning was issued, advising exchange users to call a temporary halt to XEM withdrawals. Users are still awaiting further developments, but there is some suspicion that a hack may have occurred. As Japan\'s third largest exchange, in a country with the highest cryptocurrency trading volume in the world, there is cause for concern.

One expert commentator noted that only bitcoin was still trading on Coincheck, and that a rumour is circulating that the exchange has lost some US$600m of XEM and other altcoins, including Ripple\'s XRP.

NEM Foundation have been in contact with Coincheck to monitor the situation, but their President, Lon Wong, said that NEM technology was intact, and that Coincheck might have suffered from not using their \"multi-signature smart contract.\" He described the hack as the \"biggest theft in the history of the world.\"

NEM has dropped upwards of 20% in value since the announcement.