Key Highlights

  • Kospi plunged about 4.6% to near 5,662 intraday on Friday, October 30, 2026 in Seoul while the Hang Seng rose 1.6%, a single-source figure; the Kospi close was not found.
  • Samsung Electronics had fallen about 4% on Thursday as US tech and memory shares sold off, and the Roundhill Memory ETF dropped 4% on the day.
  • Sandisk was down about 8% in premarket and SK hynix ADRs fell more than 7%, while Philadelphia Semiconductor index lost 1.42% on October 29, 2026.
  • iShares Semiconductor ETF (NASDAQ:SOXX) is a US chip proxy for this read-through; no move for the fund was verified and Korean chip exposure was not measured here.

The Seoul Sell-Off

Kospi plunged about 4.6% to near 5,662 on Friday morning in Seoul, while the Hang Seng rose 1.6%. The figure is an intraday level from a single source, the Kospi close was not found, and one page that mixed 2026 dates showed inconsistent Kospi levels, so the index level should be read with caution. Samsung Electronics had already fallen about 4% on Thursday as US technology and memory shares sold off, with the Roundhill Memory ETF down 4%. Korea's index is heavily weighted toward large memory-chip makers, which is general market context rather than a figure from the recaps, so a US chip rout can hit it hard. Memory makers' shares often move together because they sell similar products into the same cycle.

Why Memory Stocks Move Together

Memory prices are cyclical, and investors worry pricing may be nearing a peak. Sandisk fell about 8% in premarket despite Revenue of USD 11.0 billion and a Q2 guide of USD 12.2 billion to USD 12.6 billion, according to one recap. SK hynix ADRs fell more than 7%, and Kioxia's Q3 operating profit guide of 2 trillion yen was below the 2.35 trillion yen consensus, a gap of 0.35 trillion yen, simple arithmetic. For iShares Semiconductor ETF (NASDAQ:SOXX), the read-through is sector-wide: memory weakness can pull on a chip basket. The Philadelphia Semiconductor Index fell 1.42% on October 29, 2026. Memory makers' shares often move together because they sell similar products into the same cycle.

Risks and What to Watch

The key risk is that a single intraday figure misstates the day: the Kospi close, not the morning low, is what matters, and it was not found. Rebounds from sharp one-day drops are also common. For iShares Semiconductor ETF (NASDAQ:SOXX), the wider drivers include the AI capex worry after Alphabet's miss, with Nasdaq-100 futures down about 2.5%, and Fed hike pricing of about 80% for December. Watch the Seoul close, the 9:30 a.m. ET open in New York, Intel's reaction to its guide and next week's earnings. Overseas moves can be exaggerated by thin early trading, and a recovery by the close would shrink the story. These are premarket and overseas snapshots that can change.

Where Things Stand

Kospi plunged about 4.6% because Seoul's chip-heavy market followed the US tech and memory sell-off, while Hong Kong rose 1.6%, which shows the move was sector-driven rather than a broad Asia sell-off. The evidence is a single intraday figure and the close was not found. For iShares Semiconductor ETF (NASDAQ:SOXX), memory pricing worries and AI capex concerns are the link. The next catalysts are the Seoul close, today's New York open and memory-sector updates.