South Korea's KOSPI extended its early rise above the 6,600 level, triggering a buy sidecar in the main market. It was the first time in 3 trading sessions since July 31.

The Korea Exchange said a buy sidecar was triggered at 9:24:56 a.m., temporarily suspending the effectiveness of program buy orders in the main market.

At the time of activation, the nearest-month futures contract based on the KOSPI200 was at 1,049.28, up 51.20 points, or 5.12 percent, from the benchmark price of 998.08.

The sidecar conditions were met after the KOSPI200 futures price stayed more than 5 percent above the benchmark price for more than 1 minute.

As a result, the effectiveness of program buy orders in the main market was suspended for 5 minutes.

The KOSPI opened at 6,603.48, up more than 3 percent from the previous session, and extended gains early on above the 6,600 level. Buying flowed in, led by large semiconductor stocks such as Samsung Electronics and SK Hynix.

The move also reflected a more than 6 percent surge in the Philadelphia Semiconductor Index overnight in the United States, with major chip stocks such as Micron and AMD showing strength, which affected domestic investor sentiment.

A sidecar is a system that temporarily suspends the effectiveness of buy or sell orders to prevent program trading from amplifying volatility in the spot market when futures prices swing sharply beyond a certain level.