Sector Atlas 第4号｜寄りの緑、その後の選別——光接続とAI投資の資本負担
Market event: Korea and Taiwan closes; U.S. premarket on 3 Nov 2026 Verified: 3 Nov 2026, 20:21 JST What changed. The 12:18 JST update treated Korea's decline as an
Market event: Korea and Taiwan closes; U.S. premarket on 3 Nov 2026
Verified: 3 Nov 2026, 20:21 JST
What changed. The 12:18 JST update treated Korea's decline as an intraday warning and Taiwan's loss as materially smaller. The closing data strengthened the signal. Reuters reported that both South Korea's KOSPI and Taiwan's benchmark closed about 3.6% lower. Taiwan recorded its steepest one-day decline since late July. A local closing report put the KOSPI at 5,648.79, down 3.59%, with Samsung Electronics down 3.93% and SK hynix down 5.10%. Foreign investors sold a net 1.5 trillion won of Korean shares for a third consecutive selling session.
Memory demand and customer margins. Apple reported fiscal fourth-quarter revenue of US\$114.5 billion and gross margin of 47.9%. Management subsequently guided December-quarter gross margin to 45%–46%, citing higher memory costs and Siri AI expenses. Reuters reported that Apple's purchasing commitments increased by US\$33 billion during the quarter. Apple shares were down 4.5% in U.S. premarket trading. The evidence supports memory suppliers' pricing power, but it also shows that the same price cycle is becoming a margin problem for device makers and memory customers.
Rates, FX and U.S. premarket. The U.S. 10-year yield was 4.9064%, up only 1.2 basis points, and USD/JPY was near 157.8. This was not a new rate shock. U.S. premarket trading also provided counterevidence: Nasdaq-100 futures were up 0.46%, Nvidia 1.6% and AMD 2.8% before AMD's earnings, even as Apple fell. No new BOJ, Federal Reserve or Japan Ministry of Finance policy decision was identified after the previous check.
Tokyo transmission. The 4 November Tokyo open now faces a confirmed regional semiconductor shock rather than an unfinished Korean session. Memory and HBM demand can remain structurally strong while equity prices fall on positioning, valuation and customer financing concerns. Kioxia and high-beta equipment names therefore face opening-gap risk. Apple suppliers and consumer-electronics component makers face a different question: whether higher memory and AI service costs can be passed through without damaging demand or margins.
Counterevidence and next checks. U.S. figures are premarket, not closing prices. AMD reports after the U.S. close, U.S. midterm results are pending, and one complete U.S. cash session will occur before Tokyo reopens. A sustained rebound in Nvidia, AMD, Micron and the SOX, together with stable yields and USD/JPY, would weaken the regional contagion signal. A weak AMD outlook or renewed selling in memory and equipment would reinforce it.
Sources: Reuters — global markets, 3 Nov · Yonhap Infomax — Korea close · Apple — fiscal Q4 results · Reuters — Apple results and memory costs · Reuters — U.S. premarket · Reuters — FX
Market event: Korea and Taiwan cash sessions on 3 Nov 2026
Observed: 09:00–11:20 JST
Verified: 3 Nov 2026, 12:18 JST
What changed. The previous update concluded that U.S. technology weakness was selective rather than a market-wide liquidation. Asian price discovery added a more defensive signal. Reuters reported that the MSCI Asia-Pacific index excluding Japan fell 0.9%, led by a decline of as much as 3.8% in South Korea, while Taiwan fell 1.3%. Japanese cash equities were closed for Culture Day.
Korea's semiconductor leaders carried the decline. Korea Exchange opening data cited by Seoul Economic Daily showed the KOSPI opening 2.46% lower at 5,715.19. At 09:47 JST, Samsung Electronics was down 4.59% and SK hynix 5.10%. Foreign and institutional investors were net sellers at the open, while retail investors bought. These are intraday observations, not closing prices.
Old thesis and reason for revision. The earlier thesis emphasized differentiation inside the U.S. chip complex and noted that the SOX reading itself was unresolved because source displays conflicted. That caution remains. What changes is the geographic transmission: weakness moved beyond U.S. individual names into Korea's two dominant memory and HBM suppliers. The previous day's 2.24% KOSPI rebound did not survive the next opening.
Rates and FX. The U.S. 10-year yield rose only 2.1 basis points to 4.913% in Asian trading, while S&P 500 futures were up 0.1%. The move therefore cannot be attributed to a fresh broad risk-off shock or a large rate spike alone. Separately, the People's Bank of China said it would raise the foreign-exchange deposit reserve ratio to 6% from 4% on 15 November. Reuters estimated that the measure would absorb roughly \$24 billion of foreign-currency liquidity and was intended to slow recent yuan appreciation. The direct effect on USD/JPY is not yet established.
Tokyo transmission. Korea and Taiwan are functioning as the available Asian price-discovery markets while Tokyo is closed. For the 4 November Tokyo open, the probability of an opening gap in memory, semiconductor equipment and high-valuation AI infrastructure has increased. The evidence does not erase company-specific positives such as Ferrotec's upward revision or Tokyo Electron's buyback; it raises the bar for those positives to overcome sector beta.
Counterevidence and next checks. The Korean session had not closed at verification time. U.S. futures were slightly positive, Taiwan's decline was smaller than Korea's, and another U.S. cash session, AMD earnings and the U.S. midterm election will occur before Tokyo reopens. A Korean afternoon recovery, improving breadth in the next U.S. session or a strong AMD report would weaken this signal.
Sources: Reuters — Asian markets, 3 Nov · Seoul Economic Daily — Korea open and chip leaders · Reuters — PBOC FX reserve requirement · JPX — market holidays
