KOSPI, dramatic rebound after market sidecar — 2026-05-18
The KOSPI index saw a turbulent day on the 18th, briefly plunging over 5% and triggering a sell-side sidecar. However, a massive V-shaped recovery driven by aggressive buying from retail and institutional investors led the market to close at 7,510. The sell-off was fueled by soaring U.S. Treasury yields and a slump in AI tech stocks, compounded by heavy foreign selling. In contrast, the KOSDAQ remained weak, closing down for the second consecutive day at 1,111.
KOSPI Emergency Briefing — 2026-05-18
Market Snapshot
- KOSPI: Closed at 7,510 (+22p; recovered from an intraday plunge of over 5%)
- KOSDAQ: 1,111.09 (-1.66% from previous day, second consecutive day of decline)
- KRW/USD Exchange Rate: 1,500.8 KRW (+9.8 KRW, reclaiming the 1,500 level for the first time in a month)
- Market Sentiment: Extreme volatility led to a sell-side sidecar, followed by a dramatic rebound as retail and institutional investors sought bargain opportunities. The day was marked by a mix of risk-aversion and recovery expectations.
Trading Activity (KOSPI)
- Foreign Investors: Net selling — Large-scale exits early in the day due to inflation concerns and rising Treasury yields. Mixed signals in KOSDAQ with a net purchase of 237.2 billion KRW.
- Institutional Investors: Net buying — Entered the market for bargain hunting during the sharp KOSPI decline, focusing on semiconductors and large-cap stocks.
- Retail Investors: Net buying — Led the recovery after the sidecar was triggered by actively buying the dip.
Top 5 News of the Day
1. KOSPI Stages Dramatic V-Shaped Rebound Post-Sidecar
- What happened?: On the 18th, the KOSPI triggered a sell-side sidecar after falling nearly 5% early in the session due to U.S. Treasury yield spikes and a tech stock rout. It subsequently recovered to close positive at 7,510, thanks to strong retail and institutional support.
- Market Impact: Broad recovery across all sectors, particularly in semiconductors and large-caps; KOSDAQ, however, failed to regain momentum.
2. KRW/USD Rate Reclaims 1,500 Level
- What happened?: The exchange rate closed at 1,500.8 KRW, up 9.8 KRW. Woori Bank researcher Min Kyung-won noted that inflation fears and rising global yields are increasing valuation pressures, potentially heightening profit-taking risks for foreign investors in the KOSPI.
- Market Impact: While a weaker won is a short-term boon for major exporters, it heightens volatility and concerns over foreign capital flight.
3. U.S. AI Tech and Chip Rout Hits Domestic Stocks
- What happened?: U.S. semiconductor stocks tumbled 4%, creating a ripple effect. Samsung Electronics faced additional pressure from strike concerns but managed to rebound 4.25% (11,500 KRW) to close at 282,000 KRW.
- Market Impact: Extreme volatility for semiconductor heavyweights like Samsung Electronics and SK Hynix.
4. KOSDAQ Closes Down 1.66% Despite Foreign Buying
- What happened?: The KOSDAQ index fell to 1,111.09 despite 237.2 billion KRW in net buying by foreign investors. Retail and institutional investors turned to selling. Declining stocks (1,209) vastly outnumbered gainers (432).
- Market Impact: Overall weakness in KOSDAQ, though semiconductor equipment and aerospace sectors showed relative strength.
5. Warning on High-Flying Tech Stocks
- What happened?: With AI tech stocks dominating recent market trends, an analysis shows that 1 in 5 high-performing tech stocks over the last 11 years has been delisted or faced trade suspension. There is a growing call to exercise caution in an overheated market.
- Market Impact: Increased wariness regarding overvalued AI/tech themes and risks associated with small-cap thematic stocks.
Sector & Theme Focus
- Semiconductor/AI: Extreme volatility; Samsung Electronics plunged but rebounded 4.25%.
- Aerospace: Remained relatively strong compared to the broader KOSDAQ.
- Semiconductor Equipment: Selective buying in the KOSDAQ market.
- Robot/Electric/Construction: Experienced heavy selling pressure alongside the KOSPI plunge.
Top Movers
- Gainers: Samsung Electronics (+4.25%), Aerospace thematic stocks, Semiconductor equipment stocks.
- Losers: KOSDAQ large-caps (-1.66%), Robot and Construction stocks, AI small-cap tech stocks.
Global Market Links
- U.S. Treasury Yields & AI Tech: Global yield spikes are increasing valuation risks for stocks.
- Global Dollar Strength: Continued pressure on the KRW/USD exchange rate amidst geopolitical risks in the Middle East.
Tomorrow’s Checklist
- Nvidia Earnings: A crucial pivot point for semiconductor/AI sentiment that will influence domestic chip majors.
- Foreign Flow Patterns: Monitoring whether foreign investors continue their exit or switch to buying the dip.
- KRW/USD Stabilization: If the exchange rate hardens above 1,500, expect further volatility.
Action Items
- Monitor Foreign Flows: Check 9:00 AM – 9:30 AM data for clues on foreign investor sentiment.
- Review Portfolios: Adjust Samsung Electronics and SK Hynix positions ahead of the Nvidia earnings report.
- Rebalance Tech Themes: Review exposure to small-cap AI stocks given recent warnings on delistings and overheating.
This content was collected, curated, and summarized entirely by AI — including how and what to gather. It may contain inaccuracies. Crew does not guarantee the accuracy of any information presented here. Always verify facts on your own before acting on them. Crew assumes no legal liability for any consequences arising from reliance on this content.
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