Both Markets Halted at Once: 5 Warnings the Simultaneous KOSPI & KOSDAQ Circuit Breakers Triggered by the Iran War Send to Korea's Financial System

🔴 Hook

This morning (March 4), Korea's stock market stopped — twice. KOSPI and KOSDAQ both plunged simultaneously, triggering a full 20-minute trading halt — the 7th circuit breaker in KOSPI's history. The Iran War is now stress-testing Korea's financial system.

TL;DR

• At 11:22 AM KST on March 4, 2026, the KOSDAQ circuit breaker was triggered → KOSPI followed at 11:25 AM
• KOSPI threatened to break below 5,400; KOSDAQ approached 1,100 — back-to-back record-breaking declines
• The previous trigger was August 5, 2024, during the U.S.-driven 'Black Monday' — the first recurrence in ~19 months
• Iran War → 50% oil price surge → massive foreign sell-off → simultaneous KRW/USD shock at ₩1,480
• The financial authorities' '₩100 trillion+ market stabilization program' is active, but market confidence remains fragile

1. The Facts: What Happened

On the morning of March 4, both KOSPI and KOSDAQ entered a sharp decline from the opening bell. The previous session (March 3) had already delivered a shock — KOSPI –7.24%, KOSDAQ –4.62% — but overnight news of Iran War escalation (President Trump's remarks not ruling out ground troops, and expanded strikes targeting 1,000 Iranian sites) intensified selling pressure.

Timeline of Events:

A circuit breaker is triggered when KOSPI or KOSDAQ falls 8% or more from the previous close for at least 1 minute, halting all trading for 20 minutes.

2. The Cascade: Why Both Markets Fell Together

① Iran War → Crude Oil & LNG Price Explosion

U.S. and Israeli airstrikes on Iran entered their fifth day, making the threat of a Strait of Hormuz blockade feel increasingly real. International crude surpassed $108/barrel, and spot LNG prices surged 30%. Korea relies on the Middle East for ~70% of its crude oil and significant LNG supply, making the jump in import prices a direct blow to corporate earnings expectations.

② Foreigners Net-Selling for Two Consecutive Days at Scale

After ₩5.16 trillion in foreign net selling on March 3, over ₩3 trillion more poured out on March 4. Against a backdrop of extreme dollar strength, capital outflows from emerging markets accelerated, with KRW/USD hovering around ₩1,480 — fueling fears of further outflows.

③ Retail Investors Are Buying, But It's Not Enough

Retail investors net-bought ₩4.5 trillion on March 3, partially cushioning the drop — but analysts warn that 'averaging down' capacity is being depleted after two consecutive days of heavy losses.

④ Confidence in the '₩100 Trillion Response' Fading

The government, Korea Exchange, and financial regulators have announced a ₩100+ trillion market stabilization program, but without a clear timeline for deployment, the market has yet to be fully reassured.

3. Context: Today in Circuit Breaker History

Simultaneous circuit breaker triggers in both KOSPI and KOSDAQ are extremely rare in Korean market history. Notable precedents:

• March 13, 2020: COVID-19 pandemic global panic
• August 5, 2024: U.S. recession fears — 'Black Monday'
• March 4, 2026: Iran War escalation shock ← today

The common thread across all cases is external shocks (pandemic, war, foreign-driven recession fears) hitting all at once. This episode combines an energy shock with geopolitical risk — structurally similar to the 2020 COVID crisis, but with a different origin.

KOSPI has already fallen more than 20% from its January 2026 peak (estimated ~7,000), officially meeting the definition of a technical bear market.

4. Outlook: How Long Will This Last?

Short-term (1–2 weeks): The trajectory of the Iran War is the key variable. If Trump's '4–5 week war' scenario materializes, weekly shock episodes are possible. If crude exceeds $120/barrel, further foreign outflows are likely.

Medium-term (1–3 months): Key variables include the timing and scale of the Financial Services Commission's stabilization program deployment, the Bank of Korea's rate decision (current hold vs. emergency cut debate), and the U.S. Federal Reserve's response.

Risk Scenarios:

• 🔴 Worst case: Hormuz blockade persists → crude breaks $150 → stagflation materializes → KOSPI breaks below 5,000
• 🟡 Base case: Iran moves toward negotiations within 4–5 weeks → oil stabilizes → KOSPI recovers to 5,500–6,000
• 🟢 Best case: Early ceasefire → sharp oil price reversal → foreigners turn net buyers → all-time high challenge within the year

5. Checklist: What Investors Should Do Now

Reference Links

• KOSPI & KOSDAQ Circuit Breakers Triggered (Donga Ilbo, 2026.03.04)
• First KOSPI Circuit Breaker Since August 2024 (Nate News, 2026.03.04)
• KOSPI Closes at 5,791 with Sell-Side Sidecar (MBC News, 2026.03.03)
• Korea Exchange Issues Sell-Side Circuit Breaker (Korea Times, 2026.03.04)
• Iran War Energy Crisis Analysis (Korea Economic Daily)

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