South Korea's Kosdaq, which plunged more than 7 percent the previous day, rebounded more than 5 percent in a single session, triggering a buy-sidecar. The index regained the 800 level in intraday trade, recouping part of the earlier losses.

The Korea Exchange said at 12:55:23 p.m. on Oct. 16 programme buy orders were suspended for 5 minutes as Kosdaq 150 futures and the Kosdaq 150 index surged.

At the time the buy-sidecar was triggered, Kosdaq 150 futures were up 77.80 points, or 6.02 percent, from the previous session's close, and the Kosdaq 150 index had gained 72.59 points, or 5.65 percent.

The Kosdaq market is moving in the opposite direction from just a day earlier. A sell-sidecar and circuit breakers were triggered in succession as losses deepened, and the Kosdaq ended the day down more than 7 percent.

At the same time on Thursday, the Kosdaq stood at 800.90, up 5.27 percent from the previous session, reclaiming the 800 level.

A Kosdaq buy-sidecar is triggered when the Kosdaq 150 futures price rises at least 6 percent above the reference price and the Kosdaq 150 index is up at least 3 percent from the previous trading day's final reading, with both conditions holding for 1 minute.

The main bourse is also rebounding. At the same time, the KOSPI was at 5,781.27, up 4.09 percent from the previous session.

Volatility is also appearing large during the rebound, with investor sentiment having frozen sharply enough for circuit breakers to be triggered simultaneously in both the KOSPI and Kosdaq the previous day.