Kospi, Kosdaq Sink on Broadcom Shock; Won Ends at 1,539.1 per Dollar

South Korea’s Kospi and Kosdaq indexes closed sharply lower on June 5 after weak guidance from U.S. chipmaker Broadcom hit sentiment toward artificial intelligence-related semiconductor stocks. Selling centered on chip shares as investors locked in profits after Broadcom’s outlook missed market expectations.

The Kospi closed at 8,160.59, down 478.82 points, or 5.54%, from the previous session. The benchmark opened down more than 4% and extended its losses through the day, falling as low as 8,038.10 intraday.

The steep early slide triggered a sidecar, a temporary halt on program sell orders. The Korea Exchange imposed the five-minute curb at 9:08 a.m. after Kospi 200 futures tumbled. It was the 10th Kospi sell-side sidecar this year and the first in 12 trading days since May 18.

The selloff followed a deterioration in AI-related risk appetite tied to Broadcom.

On June 4, Broadcom Chief Executive Officer Hock Tan told a post-earnings conference call that third-quarter AI chip revenue would reach $16 billion. That was slightly below the market forecast of $16.36 billion. Broadcom shares fell 12.59% to close at $418.91 in regular Nasdaq trading the same day.

On the Kospi, foreign investors were net sellers of 3.5216 trillion won, while institutions sold a net 939.9 billion won. Retail investors were net buyers of 4.2212 trillion won.

Among the Kospi’s largest companies, semiconductor shares led the declines. Samsung Electronics fell 6.4% to 329,000 won, while SK Hynix dropped 9.92% to 2.07 million won. Samsung Electronics preferred shares lost 4.09%, SK Square fell 7.57%, Samsung Life Insurance dropped 5.82%, and Hyundai Mobis slid 6.82%. Samsung Electro-Mechanics rose 2.39%, HD Hyundai Heavy Industries gained 2%, and KB Financial Group advanced 4.51%.

The Kosdaq also came under pressure. The index closed at 1,002.44, down 47.29 points, or 4.5%, from the previous day. It briefly fell below the 1,000 mark in early trading and touched 992.80 during the session. Foreign investors were net sellers of 182 billion won on the Kosdaq, while institutions and retail investors bought a net 144.8 billion won and 33.9 billion won, respectively.

Most Kosdaq heavyweights also declined. Alteogen fell 4.04%, EcoPro BM dropped 8.76%, EcoPro lost 8%, Rainbow Robotics slid 6.44%, Jusung Engineering plunged 16.17%, and Kolon TissueGene tumbled 9.41%. Wonik IPS was an exception, rising 4.32%.

The won-dollar exchange rate also climbed during the session. In Seoul trading, the won opened at 1,529.0 per dollar, down 0.7 won from the previous session, then turned higher and rose above 1,540 won intraday. It finished the daytime session at 1,539.1 won per dollar, up 9.4 won from the prior close.

Kim Yeon-ji, Hankyung.com reporter kongzi@hankyung.com