The KOSPI fell below the 6,000 level during trading, while sell-sidecar curbs were triggered on both the KOSPI and Kosdaq for a second straight session, following the previous day.

The Korea Exchange said a sell-sidecar, which temporarily halts the effectiveness of program sell orders, was triggered on the main KOSPI market at 10:55:07 a.m.

At the time of the trigger, the nearest-month futures contract based on the KOSPI 200 was at 903.80, down 49.16 points, or 5.15 percent, from the base price of 952.96.

The conditions were met after the KOSPI 200 futures price stayed down more than 5 percent from the base price for 1 minute. As a result, program sell orders on the main market were suspended for 5 minutes.

On the Kosdaq, a sell-sidecar was triggered 1 minute later at 10:56:07 a.m.

At the time of the trigger, Kosdaq 150 futures were at 1,121.20, down 74.30 points, or 6.21 percent, from the previous session's close of 1,195.50.

The Kosdaq 150 was also tallied at 1,115.32, down 75.05 points, or 6.30 percent, from the previous session. With both the futures and the cash index meeting the trigger conditions at the same time, program sell orders on the Kosdaq market were also suspended for 5 minutes.

Sell-sidecar curbs were triggered simultaneously on the KOSPI and Kosdaq for a second straight trading session, following the previous day.

On July 28, after sell-sidecar curbs were triggered on both markets, the KOSPI and Kosdaq each plunged more than 8 percent, prompting a stage 1 circuit breaker.