Coincheck, Inc.

Tokyo-based cryptocurrency exchange Coincheck was hacked and lost about ¥58 billion ($532 million) worth of its holdings, sending its clients into a panic about the fate of their virtual assets.

The heist would surpassed the ¥48 billion ($390 million) lost in the collapse of bitcoin exchange Mt. Gox in February 2014 and go down as the largest cryptocurrency theft since the advent of bitcoin.

Source: https://www.databreaches.net/coincheck-hacked-in-%c2%a558-billion-cryptocurrency-heist-four-years-after-mt-gox/

"id": "COI1736291222",
"linkid": "coincheck",
"type": "Breach",
"date": "01/2018",
"severity": "100",
"impact": "5",
"explanation": "Attack threatening the organization’s existence"