South Korea's KOSPI triggered its market-wide circuit breaker three times in roughly three weeks this July — a rare burst of volatility that has traders and regulators watching closely. The first halt came on July 7 around 1:51 p.m. KST after the index fell more than 8%. A second followed on July 13, and a third about two weeks later.
How the circuit breakers work
The Korea Exchange operates a three-phase system. Phase 1 kicks in when the KOSPI drops more than 8% and stays there for one minute. That one-minute persistence rule is designed to filter out flash prints or accidental slips in index futures. Phase 2 triggers at a 15% decline, Phase 3 at 20%. Both also require a one-minute hold.
Phase 1 and 2 halts last 20 minutes. During that time, only order cancellations are allowed — no new orders can be entered. Phase 3 shuts down trading for the rest of the day. The circuit breakers can be applied only once per day and are not triggered in the final 40 minutes of the session.
The sidecar mechanism
Separate from the market-wide halt, Korea has a 'sidecar' that targets program trading tied to KOSPI200 futures. If those futures move 5%, program sell orders are suspended for five minutes. On July 13, a sell-side sidecar was triggered earlier in the morning, before the full circuit breaker arrived in the afternoon.
The sidecar affects ETF market makers by cooling the arbitrage flows between cash equities and futures. That can lead to wider spreads during volatile periods.
July 7: the first trigger
The July 7 circuit breaker was triggered around 1:51 p.m. KST. The KOSPI had fallen more than 8%, meeting the Phase 1 threshold. Trading stopped for 20 minutes. The exact cause of the sell-off wasn't specified in the available data, but the move was sharp enough to hit the one-minute persistence rule.
July 13 and the third event
Just six days later, on July 13, the KOSPI triggered another circuit breaker. That day also saw the sidecar activated in the morning, signaling stress in the futures market before the cash market halt hit in the afternoon. The third activation came roughly two weeks after July 13, meaning it likely occurred around the end of July or very start of August.
The back-to-back halts are unusual. The Korea Exchange's rules are designed to prevent exactly this kind of repeated shock, but the one-minute persistence rule is meant to avoid false starts. The fact that three genuine halts happened in such a short span suggests sustained selling pressure.
No official statement from the Korea Exchange or financial regulators has been released yet about the third event. Market participants are waiting to see whether any rule adjustments or emergency measures will follow.
