By John Detrixhe.

A South Korean bitcoin exchange called Youbit said (link in Korean) hackers had stolen 17% of its asset reserves and it now plans to file for bankruptcy.

For Yapian, the company that operates the Seoul-based exchange, it was the second breach (paywall) in less than eight months. The company said hackers broke into its so-called hot wallet, an account kept online for holding cryptoassets like bitcoin or ethereum. Youbit, which provides trading for a range of digital assets, said its offline, cold-storage holdings were still intact, and that all customers’ assets will be marked down to 75% of their value.

Youbit is a smaller exchange, but the breach underscores the difficulty such companies have had in protecting digital assets from hackers. The major platform in bitcoin’s early days, Mt. Gox, was originally designed for trading Magic: The Gathering cards. It was the leader until hackers stole from its customers, helping drive the exchange into bankruptcy. More than $70 million in bitcoin was stolen from NiceHash, a cryptocurrency-mining service in Slovenia, earlier this month.