Samsung Electronics and SK hynix had added about $73 billion of market value by 01:40 UTC on Tuesday, 10 November, by our arithmetic, as Seoul’s chip stocks rebounded. Samsung traded at 198,600 won, up 4.58% from Monday’s close, and SK hynix at 1,201,000 won, up 5.72%, according to Korea Exchange prices via Naver Finance.
The rally tripped a buy-side “sidecar” six minutes into the session. The Korea Exchange suspended program buy orders on the KOSPI for five minutes from 9:06 a.m. Seoul time (00:06 UTC), after KOSPI 200 futures rose 5.76%, Daily Hankook and DigitalToday reported. The session was still open when these figures were read; it closes at 06:30 UTC.
Business Pill · Concentration Explained
A short explainer on market concentration, when a few large companies drive an index. It teaches the general idea only and does not discuss the KOSPI or these companies.
The key insight: By our arithmetic, Samsung Electronics and SK hynix had added about $73 billion of market value by 01:40 UTC, against about $117 billion at their session highs so far: the KOSPI rally that tripped a buy sidecar at 00:06 UTC had given back about 31% of its peak index gain by then.
The Korea Exchange said buy sidecars were triggered on both the KOSPI and the KOSDAQ, Daily Hankook reported. On the KOSPI, mini KOSPI 200 futures rose 5.76% to 821.04 from a base price of 776.26 and held for one minute, triggering the five-minute halt on program buy orders. At that moment, the report says, program trading stood at 79.3 billion won of net buying and the KOSPI was at 5,264.94, up 4.9%.
The KOSDAQ followed at 9:10 a.m., with KOSDAQ 150 futures up 6.29%, according to the same report. DigitalToday puts the KOSPI trigger at 9:06:02 a.m. and reads the rebound as buying centred on semiconductors after last week’s consecutive plunges. A sidecar pauses only program buy orders; ordinary trading continues.
% change from the previous close: Seoul (KRX via Naver Finance, 01:40 UTC) and Tokyo (Yahoo Finance, 01:26 UTC, delayed) intraday on 10 November, not closing prices; Micron and Nvidia are 9 November U.S. closes (Nasdaq).
The Index Gave Some of It Back
The KOSPI opened at 5,247.22 and reached 5,300.92, up 282.07 points or 5.62% from Monday’s 5,018.85 close, by our arithmetic. At 10:40 a.m. Seoul time (01:40 UTC) it stood at 5,214.13, up 195.28 points or 3.89%. By our arithmetic, it had given back about 31% of its peak gain by then.
The two chipmakers followed the same path. At their session highs so far, Samsung at 203,500 won and SK hynix at 1,242,000 won, the pair were up about $117 billion, by our arithmetic. Advancers outnumbered decliners 689 to 194 on the KOSPI, Naver Finance data show.
By investor type, Naver Finance shows foreign investors as net buyers of about 165.5 billion won on the KOSPI so far and institutions of about 221.2 billion won, while individuals were net sellers of about 526.4 billion won.
Our Arithmetic
We multiplied each stock’s gain since Monday’s close by the share count implied by Naver Finance’s market value figure, the same basis as our earlier Korea pieces: about 5.85 billion Samsung common shares and about 730 million SK hynix shares. That gives about 50.9 trillion won for Samsung and 47.5 trillion won for SK hynix, about 98.3 trillion won together. At 1,345.60 won to the dollar, the Hana Bank rate shown by Naver Finance at 10:38 a.m., that is about $73 billion.
On 6 November, the same two stocks were about 225.6 trillion won below their 5 November close when the KOSPI was halted after an 8.6% plunge. Tuesday’s gain so far is a fraction of that.
Tokyo Rallied, Nvidia Did Not
Tokyo moved the same way. SoftBank Group traded at 3,798 yen at 01:26 UTC, up 11.71% from its previous close of 3,400, and Tokyo Electron was up 5.48%, by our arithmetic from Yahoo Finance quotes, which are delayed. The Nikkei 225 was up 2.56%. SoftBank Group’s investor calendar lists its second-quarter results for 10 November.
On Wall Street on Monday, chip stocks rose while Nvidia fell. Nasdaq data show Nvidia closed at $178.67, down 4.27%, while Micron rose 6.25%, AMD 13.26% and Broadcom 8.78%. We tracked that split during Monday’s session in Nvidia’s $184 billion early loss as four rivals added $376 billion, after a 5.1% premarket fall. Daily Hankook’s report on the sidecar notes that New York stocks rose broadly overnight, including Micron and SanDisk.
As we read the cross-market prices, the overnight split in New York carried into Asia: memory and chip peers such as Micron (up 6.25%) rose on Monday while Nvidia fell 4.27%, and on Tuesday morning Seoul’s two memory makers and Tokyo Electron were up about 4.6% to 5.7%.
As we read the flow data, the buying on the KOSPI came from foreign investors and institutions while individuals were net sellers, according to Naver Finance’s running totals at 01:40 UTC.
Daily Hankook, 10 November 2026 (our translation)
“The Korea Exchange said buy sidecars were triggered on the KOSPI and KOSDAQ markets on the 10th”
Three Implications
FOR MEMORY MAKERS Samsung was up 4.58% and SK hynix 5.72% at 01:40 UTC, about $73 billion together by our arithmetic.
FOR KOREA’S MARKET PLUMBING The KOSPI buy sidecar halted program buy orders for five minutes from 00:06 UTC, the KOSDAQ’s followed at 00:10 UTC.
FOR TOKYO SoftBank Group was up 11.71% at 01:26 UTC, on the day its investor calendar lists second-quarter results.
The framework says: “While attention remains fixed on GPU shortages and frontier model capabilities, the binding constraint on AI scaling has quietly shifted to High Bandwidth Memory (HBM).”
As we read it, Monday and Tuesday’s prices put memory makers ahead of Nvidia: Micron rose 6.25% in New York as Nvidia fell 4.27%, and SK hynix and Samsung led Seoul’s rebound. The framework was published in December 2025 and does not discuss these market moves.
What Is Not Established
These are intraday figures, not closing prices: the Seoul and Tokyo sessions were still open when they were read, and the gains can grow or shrink before the close. The investor-flow figures are Naver Finance’s running totals and change through the day. The dollar values depend on the exchange rate used. We did not reach the Korea Exchange’s own notice; the sidecar details are as the exchange described them to Daily Hankook and as DigitalToday reported.
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A buy sidecar paused program buying on the KOSPI at 00:06 UTC as the index rose as much as 5.62%. By 01:40 UTC, Samsung and SK hynix had added about $73 billion together by our arithmetic, after Monday’s U.S. session in which memory and chip peers rose and Nvidia fell 4.27%.
A note on sourcing. Seoul prices are Korea Exchange data via Naver Finance, read at 01:40 UTC on 10 November 2026, and Tokyo prices are delayed Yahoo Finance quotes read at 01:41 UTC; both sessions were open, so these are intraday figures, not closes. The sidecar details are from Daily Hankook and DigitalToday; the English renderings are our translation. U.S. figures are 9 November closes from Nasdaq. The market-value gains, the dollar conversions and the percentage changes not stated by the sources are our arithmetic.
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.
