The securities watchdog says it proactively shut down some systems after spotting the threat on 11 August.Critical functions remained available and real-time equity market surveillance operations continue as normal.However, some personal information of member firms and their registered employees appears to have been affected by the breach, says Ciro."Given the high standard of security that Ciro expects of both itself and its members, we are deeply concerned about this, and know our members will be too," says a statement.An investigation is ongoing and the regulator is working with external cybersecurity and legal experts, and law enforcement.