South Korea's bourse invoked a buy-side Sidecar mechanism for the country's benchmark KOSPI Tuesday after a sharp rally.

Shortly after the market opened, at 9:25 a.m. local time, the Korea Exchange triggered the measure, which will pause program buys for KOSPI-listed stocks for five minutes. The index, which opened 3.85% higher on Tuesday, had extended its gains to 4.53% by 9:27 a.m., fueled by optimism over a potential US-Iran agreement regarding the Strait of Hormuz and a waning of concerns over artificial intelligence investment.

The buy-side Sidecar is triggered when the KOSPI 200 futures index rises by 5% or more and maintains that level for at least one minute.