Korea Exchange activates sidecar to halt KOSPI program buying

The Korea Exchange (KRX) activated a buy-side sidecar mechanism on June 1, 2026, to temporarily halt program trading on the KOSPI following a sharp market rally. The sidecar was triggered after the KOSPI 200 Futures index surged more than 5% for at least one minute, prompting the KRX to pause algorithmic and basket trading for five minutes. During the incident, the KOSPI benchmark index rose 4.48%, reaching 8,855.68, driven largely by strong performance in technology stocks.

The sidecar mechanism is designed to stabilize market conditions by interrupting automated trading feedback loops that can exacerbate volatility. It does not halt broader market trading but targets systematic strategies that may contribute to rapid price movements. The move followed a global risk-on environment, with Wall Street’s gains and improved geopolitical sentiment spilling into Asian markets. Additionally, a last-minute wage agreement at Samsung Electronics helped lift investor sentiment, further fueling the rally.

This incident highlights the KRX’s proactive approach to managing market stability, ensuring orderly price discovery amid heightened momentum.