How much will the Korean KOSPI fall if the United States launches a war attack on Iran?
**Predicted Impact on KOSPI in Case of US Resuming War Attacks on Iran (Full Resumption) (As of April 13, 2026, Current KOSPI 5,793)**
**Short-term (within 1-2 weeks) Expected Decline: 5-12% (KOSPI 5,200-5,500 level)**
**Mid-term (within 1 month) Expected Decline: 8-20% (KOSPI 4,600-5,300 level, Worst-case scenario up to 30%)**
This is a **realistic estimate** based on **the KOSPI reaction at the time of an actual war outbreak in February-March 2026** and securities firm scenarios (Daishin Securities, Shinhan Investment & Securities, Kiwoom Securities, etc.). The KOSPI (5,793) has currently rebounded from its March low (threatening the 5,000 mark), so **the decline could be relatively large in the event of another shock**. However, the impact varies significantly depending on whether the situation is a “short-term, limited attack” versus “prolonged conflict and a renewed blockade of Hormuz.”
### 1. Impact Based on Past and Recent Cases (Actual Data for 2026)
- **Immediately after the outbreak of war in early March 2026**:
- KOSPI **plunges by up to 12% in a single day** (circuit breaker triggered), **cumulative drop of 18% over two days** → threatens the 5,100 mark. (Largest drop since the 2008 financial crisis)
- Reason: Blockade of the Strait of Hormuz + surge in oil prices to $100–$115 → concerns over inflation, a weak won, and rising corporate costs.
- Among Asian stock markets, **South Korea took the biggest hit** (Japan's Nikkei down 5% vs. KOSPI down 12%). This is due to South Korea's 70% dependence on the Middle East for crude oil and the 90% or higher transit rate of the Strait of Hormuz.
- **If a ceasefire agreement is reached (early April)**: A sharp rebound of +5–9% (sharp drop in oil prices + easing of risk-off sentiment).
- **Negotiations collapsed on April 12 (current situation)**: Already down 0.8–1.5%, but not yet at the level of a **full-scale renewed attack**.
→ **A renewed war (US renewed attack)** is highly likely to replicate the ‘initial shock’ seen in March. While geopolitical risks have already been partially priced in, the impact could be greater if the Strait of Hormuz is re-blocked and oil prices re-enter the $110–$120 range.
### 2. Securities Firm & Analyst Predictions by Scenario (Based on March-April 2026 Reports)
Scenario
Expected Decline
Expected KOSPI Level (Based on current 5,793)
Conditions
Short-term Limited Attack (Ends within 1 week)
Around 5%
5,500~5,503
Trump ‘Taco’ style limited impact, Hormuz impact limited
Long-term for 1 month
8~10%
5,214~5,300
Oil prices maintain $100~$110, inflation concerns intensify
Prolonged (6 months+)
15~20%
4,634~4,900
Hormuz complete blockade, supply chain collapse
Worst-case scenario (1 year+)
20~30%+
4,055~4,600
Global stagflation, economy Recession
**Daishin Securities**: “1-week closing → 5%, 1-month → 10%, 1-year+ → 30%+ correction” (most specific).
**Shinhan, Kiwoom, etc.**: “Real economy hit hard if oil prices surge to $120 → additional downside risk.”
**Goldman Sachs**: Global growth ↓ and inflation ↑ due to energy shock; energy-dependent countries like Korea are more sensitive. Further stock declines expected in a stagflation environment.
### 3. Key Variables Amplifying the Decline (Korea Characteristics)
- **Oil Prices & Inflation**: Re-blockade of Hormuz → WTI $110~$130 possible. Costs for Korean companies (automotive, chemical, semiconductor) skyrocket → deterioration of earnings.
- **Exchange Rate**: Won/Dollar re-enters the 1,500 KRW range → acceleration of foreign selling.
** - **Supply and Demand**: Simultaneous selling by foreign and institutional investors (large-scale outflows continued in March).
- **Positive Buffer**: Semiconductor and AI sectors are relatively strong, while **Energy, Defense, and Refining Stocks** (SK Innovation, S-OIL, Hanwha Aerospace) may actually rise.
### 4. Realistic Outlook and Investment Reference
- **Most Probable Scenario**: **Rebound following a short-term 5–8% correction** (Trump does not want a prolonged conflict + recovery within one month based on past patterns). Possibility of transitioning into earnings season after testing the support level of 5,300–5,500 on the KOSPI.
- **Worst-case scenario difficult to avoid**: Actual re-blockade of Hormuz + deployment of US ground forces → 15%+ decline (4,900 level).
- **Speed of Recovery**: All six past instances of Middle East risks **turned upward within one month**. There are also many views that this presents a buying opportunity at the bottom following a short-term shock.
**Caution**: This is a **hypothetical scenario**, and actual conditions fluctuate in real-time depending on the scale of the attack, Iran's reaction, oil price movements, and Trump's remarks. Please monitor Hormuz news and oil prices (currently around $98–$100) in real-time during trading on Monday, April 13. Expected to be highly volatile → Focus on short-term trading; consider increasing exposure to energy and defense sectors. (Investment decisions are at your own risk; refer to the latest brokerage reports is recommended.)
Additionally, please let me know if you have further questions regarding specific scenarios (e.g., when oil prices reach $120) or the impact on specific themes!
