Yes, the KOSPI hit circuit breakers but this is largely a catch-up move following Friday’s sell-off in the US .
The Korean market’s regular session runs from 09:00 to 15:30 KST (20:00 to 02:30 ET), with extended/off-hours trading from 07:30 to 18:00 KST (18:30 to 05:00 ET).
US equities trade from 09:30 to 16:00 ET in the regular session with extended trading running from 04:00 to 20:00 ET.
So today’s move is less the Korean market pricing in what happened in the US after its own market had closed...