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Bank display board in Seoul showing the Kospi at 6,838.04, down 0.48%
Photo: Seoul Economic Daily / Yonhap

Kospi Falls 18.8% in Q3 After Memory-Chip Selloff

Seoul Economic Daily2 min read5 sources

Why did the Kospi fall 18.8% in Q3?

Kospi (KS11) fell 18.8% in the third quarter to close at 6,838.04 on Wednesday, the worst of any major market, after memory-chip selloffs and forced liquidations of leveraged Samsung and SK Hynix bets.

Key numbers

Kospi Q3 change-18.8%worst major market
Kospi close, Sept 306,838.04-0.48% on the day
Kospi 2026 so far+62.3%trails Taiwan's Taiex at +66.3%
Samsung + SK Hynix index weight~50%from ~25% at end of 2025 (per [4])
Foreign net selling, last 3 sessions₩8.97Tretail net bought ₩1.17T on Sept 30
Q3 drop, alternate calculation-19.05%Investing.com figure; others show -18.8%

What happened

Kospi (KS11) fell 18.8% in the third quarter to close at 6,838.04 on Wednesday, the worst of any major market, after memory-chip selloffs and forced liquidations of leveraged Samsung and SK Hynix bets. Samsung Electronics and SK Hynix now make up about half the index, up from a quarter at the end of last year, so their fall dragged it down. Funds that make double-sized bets on single stocks added fuel: when prices fell, borrowed money had to be repaid, forcing more selling. The index is still up about 62% for 2026.

Why it matters

The Kospi shows how fast a stock market can fall when a few AI-linked chip companies make up half of it and many investors are borrowing to own them. Even after the quarterly drop, the index is still up about 62% this year. Samsung and SK Hynix now trade at only 4 to 5 times their expected yearly profits, a low price tag by most standards.

Who this affects

Marketbearish
High impact
Korean stock investors, especially leveraged retail traders, took heavy losses.
Companybearish
High impact
Samsung and SK Hynix shares fell as foreign investors kept selling.
Competitorsmixed
Low impact
Taiwan's market held up better, gaining 4.5% in the quarter.
Industrybearish
Medium impact
Memory-chip makers now trade at low profit multiples.

Kospi vs Nikkei 225, Taiex, S&P 500

KospiKS11-18.8%+62.3%
Nikkei 225N225-4.6%—
TaiexTWII+4.5%+66.3%
S&P 500SPX+2%—

As of 2026-09-30

How we got here

  1. Kospi drops 2.7% to 6,889.74; Samsung and SK Hynix each fall about 5%.

  2. Kospi closes at 6,838.04, down 0.48%, its third straight daily decline.

  3. Third quarter ends with Kospi down 18.8%, worst among major markets.

What to watch

  • Whether foreign investors keep selling Samsung and SK Hynix after ₩8.97T net sold in three sessions.Q4 2026
  • US 30-year Treasury yield, at 5.519% on Sept 28, its highest since 2004, and oil near $100.Q4 2026
  • Reported US IPO preparations at SK Hynix subsidiary Solidigm, which weighed on the stock.Q4 2026

Educational content only. Not investment advice.

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