[DigitalToday reporter Sangyeob Oh (오상엽)] South Korea's KOSPI plunged more than 5 percent on Friday to retreat to the 8,160 level. The spillover from weakness in U.S. semiconductor shares stemming from Broadcom spread to local chip heavyweights, and investor sentiment shrank sharply after a sell-sidecar was triggered early in the session on the main board.

The KOSPI ended down 478.82 points, or 5.54 percent, at 8,160.59. It opened down 316.21 points, or 3.66 percent, at 8,323.20 and slid as far as the 8,000 level during the session.

The Korea Exchange triggered a sell-sidecar on the main board at 9:08:25 a.m. The move came after KOSPI 200 futures stayed down more than 5 percent from the benchmark price for more than 1 minute. Program sell orders on the main board were suspended for 5 minutes.

By investor category, retail investors were net buyers of 4.2242 trillion won. Foreigners and institutions were net sellers of 3.5210 trillion won and 943.5 billion won, respectively, driving the index lower. Downward pressure on the KOSPI grew as foreign selling concentrated in chip heavyweights.

Most of the top market-cap stocks fell. Samsung Electronics closed at 329,000 won, down 6.40 percent, and SK Hynix slid 9.92 percent to 2.07 million won.

Elsewhere, SK Square fell 7.57 percent, LG Energy Solution lost 1.90 percent, Samsung Life fell 5.82 percent and Samsung C&T dropped 13.93 percent. Hyundai Motor ended flat.

Samsung Electro-Mechanics rose 2.39 percent and HD Hyundai Heavy Industries gained 2.00 percent.

The market weakness was seen as the combined impact of sluggish U.S. semiconductor shares and the burden of the exchange rate. Disappointment tied to Broadcom led to broad weakness in U.S. chip stocks, and profit-taking selling hit semiconductor bellwethers such as Samsung Electronics and SK Hynix in the local market.

The won-dollar exchange rate climbed into the 1,540-won range, adding to the burden on foreign flows. The slide was also seen as amplified by short-term surge pressure, with the KOSPI having kept up a record-high trend recently.

The Kosdaq also sank. It ended down 47.29 points, or 4.50 percent, at 1,002.44. It pared losses at one point but widened declines again in afternoon trade to close in the low 1,000s.

A key feature of the session was that both the KOSPI and Kosdaq fell sharply as weakness in chip heavyweights shook the broader market. Some stocks, including Samsung Electro-Mechanics and HD Hyundai Heavy Industries, rose and showed differentiated moves.

In the Seoul foreign exchange market, the won ended at 1,540.40 per dollar, up 6.40 won from the previous session.