South Korean cryptocurrency exchange Coinrail was hacked on Sunday, losing about 30 percent of the coins traded there.
The site has temporarily suspended trading as it works with investigators.
A statement on the exchange's site sought to reassure users -- saying that the remainder of the coins were "safely stored" -- but Reuters reports that the value of Bitcoin tumbled to two-month lows in the hack's aftermath.
It notes that Bitcoin was trading at $6,790.88 on Bitstamp, a drop of 10.8 percent from Friday and a massive dip from its December 2017 peak, when it hit an all-time high of almost $20,000.
On June 3, Brisbane Airport started allowing customers to use cryptocurrency as payment at all its retail outlets in an effort to build up its real-world use.