Information verified at: 16:10 on November 5, 2026, Korea Standard Time (KST, UTC+09:00; 07:10 UTC on the same day). The figures below were verified based on the close of the Korean regular market on November 5.
On Thursday, November 5, 2026, the South Korean stock market plummeted, centered on large-cap semiconductor stocks. The KOSPI closed at 5,383.80, down 300.00 points (5.28%) from the previous trading day, and Samsung Electronics (005930) finished trading at 201,500 won, down 16,500 won (7.57%) . With the KOSPI breaking below the 5,400 mark and Samsung Electronics plunging, attention is now focused on foreign investor sentiment and the trends of US semiconductor stocks for the next trading day.
The directly confirmed facts are large-scale net selling by foreign investors, a simultaneous decline in semiconductor stocks, and the triggering of sell- side circuit breakers. The main background cited in the market is caution regarding the possibility of stricter licensing and regulations for artificial intelligence (AI) data centers following the U.S. midterm elections. However, this does not mean that the policy has already been implemented or that Samsung Electronics' semiconductor orders have actually decreased, nor can a single cause be proven based solely on the daily decline rate.
The regular trading hours of the Korea Exchange are from 09:00 to 15:30 KST (UTC+09:00) Seoul time, which is equivalent to 00:00 to 06:30 UTC. Below are the closing prices and changes compared to the previous trading day, aggregated after the close of the regular session on this day. Since real-time or delayed quote screens may display intraday figures depending on the update time, it is necessary to distinguish them from the closing prices of the regular session.
| Indices and stocks | November 5 closing price | Compared to the previous trading day |
|---|---|---|
| KOSPI | 5,383.80 | -300.00 points (-5.28%) |
| Samsung Electronics (005930) | 201,500 won | -16,500 won (-7.57%) |
| SK Hynix (000660) | 1,264,000 won | -9.46% |
| KOSDAQ | 678.41 | -36.54 points (-5.11%) |
The KOSPI opened lower at 5,580.09 and widened its losses; as selling volume increased during the session, a sell-side car was triggered, suspending the effectiveness of program sell orders for five minutes. A sell-side car was also triggered on the KOSDAQ. Since a sidecar is a different mechanism from a circuit breaker, which halts all spot market trading, it is inaccurate to say that "trading in the stock market has been completely suspended."
Just because the index plummeted does not mean all stocks declined. On the same day, Hyundai Motor rose 3.53%, KB Financial Group 3.63%, and Celltrion 7.50%. The impact was particularly severe on semiconductor and AI-related stocks, and sector differentiation emerged as buying interest dispersed to some stocks in the automotive, financial, and bio sectors.
Following the U.S. midterm elections on November 3, investors re-evaluated the potential impact of changes in the political landscape of the U.S. Congress on the construction of new AI data centers and licensing related to power and the environment. Market analysts argued that stricter regulations could delay data center construction or server investment schedules, potentially lowering future demand expectations for Korean companies supplying High Bandwidth Memory (HBM) and server DRAM.
This is the market's interpretation of risk factors , not to mean that new regulations have been implemented at all data centers or that order cancellations for Samsung Electronics have been confirmed as of November 5. Analysis suggests that the relative weakness of semiconductor-related stocks in the U.S. market on November 4 also weighed on investor sentiment toward major Korean semiconductor stocks. However, one should not conclude that the direction of the semiconductor sector aligned with the overall movement of U.S. stock indices.
On November 5, foreign investors net sold approximately 3.4 trillion won in the securities market based on preliminary figures . It was reported that individual investors net bought about 2.27 trillion won, and institutional investors net bought about 0.84 trillion won. Since the net selling amount by foreign investors can vary by tens of billions of won depending on the source and time of compilation immediately after trading, it is more accurate not to treat the figures down to the decimal point as final.
While foreign selling indicates that selling pressure actually existed, it does not prove that the selling itself was triggered by a single piece of news. It is possible that a combination of factors, such as reduced risk in global semiconductor stocks, portfolio weighting adjustments, spot and futures hedging, and automated trading driven by increased volatility, played a role. It is impossible to isolate which of these factors contributed the most based solely on these supply and demand figures.
As Samsung Electronics is a key semiconductor stock with a large market capitalization, its stock price may become more sensitive when expectations for U.S. AI infrastructure investment waver. However, one cannot conclude that semiconductor performance has deteriorated or that there is a definitive decrease in orders based solely on the magnitude of the stock price decline on this day.
Conversely, Samsung Electronics announced on October 29 that its consolidated results for the third quarter of 2026 showed revenue of 195.3 trillion won and an operating profit of 107.4 trillion won. The company cited increased demand for HBM4 and server memory and presented a positive outlook for semiconductor performance in the fourth quarter. Even if recently disclosed earnings and business outlooks remain robust, stock prices can plummet in the short term due to uncertainty regarding future demand or valuation adjustments. Furthermore, a company's official forecasts do not guarantee future performance.
The next regular trading day is Friday, November 6, 2026. It should be based on the Korea Exchange's standard regular trading hours in Seoul, 09:00–15:30 KST (UTC+09:00; UTC 00:00–06:30); however, if the Exchange announces a separate change in operations, that announcement must take precedence. The following are scenarios based on conditions to be observed, rather than directional predictions or target prices.
If semiconductor stocks stabilize during U.S. trading hours on November 5, and the resolution of policy uncertainty becomes more prominent than specific restrictions regarding data center regulations, and if the intensity of net selling by foreign investors eases in the Korean market on November 6, a technical rebound centered on large-cap semiconductor stocks is possible. However, a single day's rebound alone cannot confirm the end of the downtrend.
If there are no new policy announcements and U.S. tech stocks fail to show a clear direction, semiconductor stocks, which have suffered heavy declines, may continue to diverge from other sectors such as automobiles, finance, and biotechnology while fluctuating significantly. It is difficult to conclude that overall market sentiment has recovered based solely on a slight rebound or a flat decline in the composite index.
Volatility in the KOSPI and Samsung Electronics could increase further if U.S. semiconductor stocks fall additionally, specific data emerges regarding data center construction delays or tightening regulations, and foreign investors continue selling spot shares domestically. Rather than arbitrarily setting price floors or short-term targets, it is necessary to verify actual supply and demand and official announcements.
Basic data and operational information can be found in the Korea Exchange Information Data System and the Korea Exchange Regular Trading Hours Guide . The primary source regarding Samsung Electronics' performance and business outlook is the Samsung Electronics Q3 2026 earnings announcement . The closing figures for November 5 were cross-referenced with multiple market close reports citing data from the Korea Exchange, and supply and demand figures are provisional.
Selling pressure on semiconductor stocks due to concerns over U.S. AI data center regulations and net selling of approximately 3.4 trillion won by foreign investors are cited as the key background. However, it cannot be definitively concluded that any single factor explains the entire extent of the decline.
There is no basis to conclude so. The previous official quarterly earnings announcement was solid, and on that day, the market's reassessment of risks regarding AI investment prospects was interpreted as the main backdrop.
A rebound is possible but not guaranteed. It is necessary to monitor the trends of U.S. semiconductor stocks, actual policy changes, and foreign investor supply and demand; this article is not a recommendation to buy or sell any specific stock.
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