The attack affected 42 of ION’s clients and was conducted by Russian ransomware gang, Lockbit, a spokesman confirmed to Bloomberg.

In a statement on its Website, ION says: "ION Cleared Derivatives, a division of ION Markets, experienced a cybersecurity event commencing on 31 January 2023 that has affected some of its services. The incident is contained to a specific environment, all the affected servers are disconnected, and remediation of services is ongoing."

Some brokers have resorted to manual workarounds to deal with the issue, which has the potential to impact margin calls, the valuation attached to portfolios and regulatory reporting of large market positions.