Samsung Electronics and SK hynix had lost about $118 billion of combined market value by midday in Seoul on 5 November, by our arithmetic on Korea Exchange data. At 12:10 to 12:11 Korea time SK hynix was down 8.4% and Samsung 5.7% from the 4 November close, and the KOSPI was down 4.0% after falling as much as 5.2%.
Yonhap reported that the fall followed the Democratic Party’s victory in the US midterm elections, which it said raised “concerns over tighter regulations on artificial intelligence (AI) data centers”. The Korea Exchange activated a sell-side sidecar on the KOSPI at 10:16 a.m., according to Yonhap.
Business Pill · Concentration
A short Business Engineer explainer on concentration: when a few big pieces make up most of a total. It teaches the general idea only and says nothing about Samsung, SK hynix or the KOSPI.
The key insight: By our arithmetic on Korea Exchange data, Samsung Electronics and SK hynix had lost about 158.5 trillion won, or about $118 billion, of combined market value by 12:11 Korea time on 5 November, more than the 126.4 trillion won they regained the day before. Yonhap tied the fall to concerns that the new US Congress would tighten regulations on AI data centres.
These are intraday prices read at 12:10 to 12:11 Korea time (03:10 to 03:11 UTC), about three and a half hours before the 15:30 close; they are not closing prices.
The KOSPI stood at 5,456.25, down 227.55 points from 5,683.80. It opened at 5,580.09 and touched 5,386.29 at 10:21, 5.2% below the previous close by our arithmetic, and below its 4 November intraday low of 5,421.72.
SK hynix traded at 1,279,000 won, down 117,000 won from its 4 November close of 1,396,000 won; its low of 1,261,000 won was 9.7% below that close. Samsung Electronics traded at 205,500 won, down 12,500 won from 218,000 won, after a low of 202,500 won, 7.1% below. Both lows also came at 10:21.
By our arithmetic, SK hynix had fallen about twice as far as the index, 8.4% against 4.0%.
Percentage change from the 4 November close for SK hynix, Samsung Electronics and the KOSPI at 12:10 to 12:11 Korea time on 5 November 2026, from Korea Exchange data on Naver Finance. Intraday prices, not the close. The intraday lows are our arithmetic from the Korea Exchange lows.
What Was Posted on X
Meritz Securities (South Korea):
Genuine demand reflected in orders received by memory chipmakers for 2027 and 2028 far exceeds their supply capacity. Even if the Democratsโ blue wave leads to some delays and adjustments, the supply shortage is unlikely to change materially.
This year, the memory order fulfillment rateโavailable supply capacity relative to order volumeโhas remained in the low-to-mid 80% range, driving sharp increases in selling prices. The shortage is expected to worsen in 2027, with the fulfillment rate falling to around 80%.
Meanwhile, during a recent visit to South Korea, OpenAI CEO Sam Altman asked SK hynix and Samsung Electronics to supply specialty memory, including HBM, for 2027โ2030 in volumes beyond what they can accommodate.
@jukan05 relays a Meritz Securities note on memory orders and supply for 2027 and 2028. The piece uses its order and fulfillment-rate figures as an attributed analyst view, as relayed; we have not read the note itself, and we have not verified the post’s line about OpenAI.
The Value Lost
Our arithmetic multiplies each fall from the 4 November close by the share count implied by Naver Finance’s market value figures: about 5.85 billion Samsung common shares and about 730 million SK hynix shares.
On that basis SK hynix had lost about 85.5 trillion won of market value and Samsung about 73.1 trillion won, 158.5 trillion won together. At 1,343.90 won to the dollar, the Hana Bank rate at 12:10, that is about $63.6 billion and $54.4 billion, or about $118 billion combined. At the 10:21 lows the combined figure was about 189 trillion won.
The two companies were worth about 2,294 trillion won together at the 4 November close, so the midday loss is about 6.9% of that, by our arithmetic. It is also more than the roughly 126.4 trillion won the two regained between their lows and the close the day before, as we reported in Samsung, SK Hynix Regain $94B From Midterm Results-Day Lows.
The Stated Cause
Yonhap’s late-morning report said investors “were worried about the future of U.S. artificial intelligence (AI) policies after the midterm elections”. It said the outcome “raised concerns that the new House and Senate would tighten regulations on AI data centers”.
Yonhap reported that major Wall Street indexes finished higher overnight, while the PHLX chip index fell 3.1% to a six-month low on concerns about stricter regulation of AI data centres by the new Democratic-led Congress.
Other chip-related shares fell too. At 11:20, Yonhap reported, Hanmi Semiconductor was down 7.58% and Samsung Electro-Mechanics 10.04%. Yonhap said the sidecar suspended program trading on the KOSPI for five minutes; it is triggered when the KOSPI 200 futures index falls 5% or more for at least one minute.
Who Was Selling
Naver Finance’s investor data at 12:10 showed foreign investors as net sellers of about 1.72 trillion won of KOSPI shares, while individuals were net buyers of about 1.31 trillion won and institutions about 0.25 trillion won. The fall was not uniform: 461 KOSPI stocks were down and 421 were up.
Analyst view, 5 Nov, 03:20Z: Meritz Securities says memory orders far exceed supply. A Meritz Securities note, as relayed on X by @jukan05 at 02:59 UTC, says orders received by memory chipmakers for 2027 and 2028 far exceed their supply capacity, and that “Even if the Democrats’ blue wave leads to some delays and adjustments, the supply shortage is unlikely to change materially.”
The note, as relayed, puts this year’s memory order fulfillment rate, available supply capacity relative to order volume, in the low-to-mid 80% range and expects it to fall to around 80% in 2027.
We have not read the Meritz note itself; the figures are as relayed. The post also relays a claim about requests from OpenAI’s chief executive to the two companies, which we have not verified and do not use.
As we read the two sessions together, the 4 November rebound came before the full result, and the 5 November fall priced the result Yonhap describes: a Democratic-led Congress and concerns over tighter data-centre rules.
As we read the prices, SK hynix falling about twice as far as the KOSPI puts the most pressure, of the two, on the company more focused on memory chips.
As we read the investor data, foreign investors were the net sellers and Korean individuals the net buyers by midday, the same split our 4 November piece recorded.
Yonhap, 5 November 2026, on the KRX sidecar
“The index came under downward pressure following the Democratic Party’s victory in the U.S. midterm elections, raising concerns over tighter regulations on artificial intelligence (AI) data centers.”
Three Implications
FOR MEMORY MAKERS The midday loss of about $118 billion is our arithmetic on intraday prices; the day’s figure depends on the 15:30 Korea time close.
FOR KOREA Chips made up 49% of Korea’s exports in October, as we reported, so US data-centre demand matters to the country’s trade figures as well as its stock market.
FOR US DATA-CENTRE BUILDERS Yonhap ties the Seoul fall to US regulation concerns; we reported data center limits leading 40 of 41 votes, and Microsoft’s capex coming in about $5 billion short, as reported by The Information.
The analysis says: “HBM growth is outpacing accelerator demand, making memory the rate-limiting factor in the AI scaling equation.”
As we read it, the framework is about supply, and the Seoul session priced the demand side: Yonhap ties the fall to concerns over tighter rules on US AI data centres, the buildings where that memory ends up. The analysis predates the election and does not discuss it.
What Is Not Established
Yonhap attributes the fall to regulation concerns after the election; no regulation has been proposed or passed in what we read, and the reports do not say which rules investors expect. Prices moved on the day for reasons the reports may not capture.
All prices here are intraday, not closing prices. We read Yonhap’s reports in full, but not Reuters, Bloomberg or the Korea Herald, and we did not see the Korea Exchange notice itself. The share counts are implied by Naver Finance’s market values, and Samsung’s covers common shares only.
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By 12:11 in Seoul, SK hynix was down 8.4% and Samsung 5.7%, and the KOSPI 4.0% after falling as much as 5.2%, according to Korea Exchange data; the Korea Exchange activated a sell-side sidecar at 10:16, according to Yonhap. By our arithmetic the two chipmakers had lost about $118 billion of market value, more than they regained the day before.
A note on sourcing. Prices, lows, investor flows and the exchange rate are Korea Exchange and Hana Bank data read on Naver Finance at 12:10 to 12:11 Korea time (03:10 to 03:11 UTC) on 5 November 2026; they are intraday, not closing, prices. The stated cause and the sidecar are as reported by Yonhap. Market value losses, share counts and percentages of lows are our arithmetic; Samsung’s share count covers common shares only. We did not contact either company.
Gennaro Cuofano is a CRO and tech executive who has worked in AI since late 2015, starting with bringing NLP, natural-language generation, voice and chatbot products to the marketing industry. His background is in law and finance: he holds a Master's degree in Law and an International MBA with an emphasis on corporate finance (LUISS Business School and the University of San Diego, 2012), and worked as a financial analyst at a real-estate investment firm in San Diego and as an assistant controller. His work focuses on business model strategy, business engineering and, more broadly, structural analysis: how companies make money, read from their own filings. He created FourWeekMBA and leads research there and at The Business Engineer, his newsletter on AI and business strategy, with over 95,000 subscribers and more than 1,000 published analyses. His writing has also appeared on Entrepreneur (for example, How to Digitize a Family Business in Europe) and HackerNoon. Find him on LinkedIn and Substack. See how we source.
