Coincheck said that around 523 million of the exchange’s NEM coins were sent to another account around 3 a.m. local time (1 p.m. ET Thursday), according to a Google translation of a Japanese transcript of the Friday press conference from Logmi. The exchange has about 6 percent of yen-bitcoin trading, ranking fourth by market share on CryptoCompare.

The stolen NEM coins were worth about 58 billion yen at the time of detection, or roughly $534.8 million, according to the exchange. Coincheck subsequently restricted withdrawals of all currencies, including yen, and trading of cryptocurrencies other than bitcoin.

Bloomberg first reported the hack. A CNBC email sent to Coincheck’s listed address bounced back.

Cryptocurrency NEM, which intends to help businesses handle data digitally, briefly fell more than 20 percent Friday before recovering to trade about 10 percent lower near 85 cents, according to CoinMarketCap. Most other major digital currencies, including bitcoin, traded little changed on the day.

Source: Japanese cryptocurrency exchange loses more than $500 million to hackers