One of Japan's largest Digital currency exchanges says it has lost some $534m (£380m) worth of virtual assets in a hacking attack on its network.
It may be unable to reimburse the funds lost on Friday, a representative told Japanese media.
If the theft is confirmed, it will be the largest involving digital currency.
Another Tokyo exchange, MtGox, collapsed in 2014 after admitting that $400m had been stolen from its network.
The stolen Coincheck assets were said to be kept in a "hot wallet" - a part of the exchange connected to the internet. That contrasts with a cold wallet, where funds are stored securely offline.
Coincheck says it has the digital address of where the assets were sent.