South Korean stocks suffered a broad sell-off on October 30 as concern over the cost and near-term returns of artificial intelligence investment spread from US technology shares to Seoul. The Kospi closed at 5,730.74, down 206.92 points, or 3.48 percent, after falling as low as 5,599.42 during the session. The decline briefly pushed the index below 5,600 and triggered a sell-side program trading curb at about 10:05 a.m., the first such activation in 11 trading days.
Foreign investors intensified the pressure by selling a net 1.62 trillion won of shares on the main market. Individuals bought about 620 billion won and institutions purchased roughly 740 billion won, but those inflows did not offset the foreign selling. The imbalance showed how rapidly concern originating in US technology earnings moved into a Korean market with heavy exposure to semiconductor leaders.
Foreign selling deepens the retreat
Samsung Electronics fell 3.02 percent to 225,000 won, while SK Hynix dropped 7.08 percent to 1.418 million won. Selling also spread from the two chipmakers to semiconductor materials, components and equipment companies. The Kosdaq lost 3.83 percent to finish at 724.38 after touching an intraday low of 717.27, confirming that the retreat was not confined to the largest stocks.
The shock followed disappointing results and investment signals from major US technology companies. Alphabet was at the center of the concern after third-quarter revenue fell short of expectations and heavy AI infrastructure spending pushed free cash flow into negative territory, according to the supplied reports. Its shares fell 12.64 percent in the US market. Reports also cited weaker-than-expected results from Amazon and Intel as contributing to the broader reassessment of technology valuations.
The market reaction was driven less by a rejection of AI demand than by uncertainty over how quickly enormous infrastructure spending can produce cash returns. When a major platform company reports weaker revenue alongside negative free cash flow, investors have less room to treat capital expenditure as a distant concern. That reassessment affected Korean semiconductor shares because expectations for sustained AI infrastructure investment have supported demand assumptions and valuations across the chip supply chain.
AI spending returns come under scrutiny
The decline was substantial but not uniform. Samsung Biologics, LG Energy Solution, Celltrion and Samsung SDI were among the large companies that rose, indicating that investors were differentiating between sectors rather than abandoning the entire market at the same rate. Even so, simultaneous losses in the Kospi, Kosdaq and leading semiconductor stocks left technology-heavy portfolios facing the sharpest immediate impact.
- Kospi intraday low
- 5,599.42
- Kosdaq close
- 724.38, down 3.83%
- Foreign net selling
- About 1.62 trillion won on the main market
A quick rebound cannot be established from the available evidence. Analysts cited in the supplied reporting said expectations for strong semiconductor earnings had already been reflected considerably in share prices, leaving the market vulnerable to continued short-term volatility. The scale of foreign selling and the spread of losses into smaller suppliers suggest that stabilization will require more than a single resilient session from one or two large companies.
Attention now turns to whether US technology companies can demonstrate that AI investment is generating sufficient revenue and cash flow, and whether foreign investors reduce their selling in Seoul. Some analysts said policy uncertainty could ease after the November 3 US midterm elections, allowing Korean corporate earnings growth and relatively low valuations to regain attention. That view remains conditional because the election outcome could also affect the pace of US AI investment, while the evidence provides no firm timetable for a Korean market recovery.