SEOUL, May 21 (Xinhua) -- South Korean stocks surged over 8 percent Thursday amid a frenzy of buying throughout the session after triggering buy sidecars in the morning trading.
The benchmark KOSPI soared 606.64 points, or 8.42 percent, to close at 7,815.59, while the smaller KOSDAQ spiked 49.90 points, or 4.73 percent, to finish at 1,105.97.
The KOSPI opened 3.85 percent higher and extended early gains throughout the session, activating buy sidecars in both the KOSPI and the KOSDAQ markets.
The sidecar refers to a temporary halt of program trading orders for five minutes that is triggered when the KOSPI 200 futures rise or fall by more than 5 percent.
Institutional investors led the dramatic rally, while retail and foreign investors were net sellers to take profits.
The stock market rally was driven by the tentative agreement on performance bonuses between the management and the labor union of Samsung Electronics that averted a general strike originally set to begin on Thursday.
Concerns weakened about the Middle East tensions after reports that negotiations between the United States and Iran entered the final stages.
The South Korean won versus U.S. dollar exchange rate finished its daytime session at 1,506.1 won per dollar as of 3:30 p.m. local time (0630 GMT), down 0.7 won from the previous session's daytime close.
Market bellwether Samsung Electronics and memory chip giant SK Hynix jumped 8.51 percent and 11.17 percent.
The country's top automaker Hyundai Motor soared 12.50 percent, and the largest battery maker LG Energy Solution picked up 4.29 percent.
The No. 1 biopharmaceutical contract manufacturer Samsung Biologics rose 4.34 percent, but the leading aerospace and defense company Hanwha Aerospace lost 0.08 percent.
The biggest shipbuilder HD Hyundai Heavy Industries advanced 5.66 percent, and the energy infrastructure leader Doosan Enerbility was up 7.01 percent. ■