Now another major exchange may be putting its users through a small-scale replay of that crisis.

Early Monday, a UK- and Slovenia-based bitcoin exchange Bitstamp announced that it would be going offline while it investigated a security compromise of some portion of its stored currency that occurred over the weekend. In a statement to WIRED, the company said that "less than 19,000″ bitcoins were stolen in the attack—about $5.1 million dollars—and warned users to immediately stop making deposits to any addresses it issued before 4 a.m. ET Monday. Meanwhile, Bitstamp users' money remains frozen in the company's accounts.

"Bitstamp takes our security and soundness very seriously," reads a statement on the company's website. "In an excess of caution, we are suspending service as we continue to investigate. We will return to service and amend our security measures as appropriate."