Crash 12% as Iran War and Oil Prices Hit Korea

South Korea’s Kospi, until days ago one of the world’s hottest stock markets, has just suffered a brutal reversal as the widening war with Iran and spiking oil prices trigger a wave of panic selling. The benchmark plunged as much as 11-12% intraday on Wednesday, with one print showing it down 11.5% to 5,805 and another reading 12.1% to around 5,791 before dip‑buyers trimmed a portion of the losses.

TradingEconomics data show the index closing near 5,2 points, down 7.24% from the previous session, its worst day in years and a collapse that wiped out a big chunk of 2026’s spectacular gains.

The Korea Exchange was forced to temporarily halt trading after a sell‑side circuit breaker was triggered, while the tech‑heavy Kosdaq also saw trading paused after dropping more than 8% and later finishing down around 12%. This is a swing for a market that had rallied roughly 50% year‑to‑date through the end of February, driven by semiconductor and AI‑related names, and was up more than 100% versus a year earlier.

Oil Shock and Hormuz Fears Slam an Import‑Heavy Economy

The immediate driver is the energy shock. Brent crude has jumped to about 82-83 USD per barrel, up more than 13% since the Iran war began, while U.S. benchmark WTI is trading around 75-76 USD. Investors fear that Iran’s moves around the Strait of Hormuz, the narrow gateway through which roughly a fifth of globally traded oil passes could squeeze fuel‑import‑dependent economies like South Korea, Japan and Taiwan.

Mizuho Bank estimates that higher insurance and shipping costs could add an extra 5-15 USD per barrel to effective crude costs, further pressuring margins and inflation.

Chipmakers and exporters, the heart of the Kospi story, bore the brunt of the selloff. Samsung Electronics fell between 9% and nearly 12% in different sessions, while SK Hynix dropped about 6-10% as investors took profits after a massive AI‑driven rally. Airline and tourism names also slid as higher jet fuel prices and war‑related travel jitters hit sentiment across Asia.

From “World’s Hottest Market” to Volatility Epicenter

Just last week, the Kospi was being hailed as the world’s top‑performing index in 2026, with global funds pouring more than 7 billion USD into Korean equities over two sessions and program trading circuit breakers tripped on the upside. Now, that same leverage and crowded positioning are amplifying the downside as geopolitical risk forces a rapid de‑risking.

The index is still up over 100% versus a year ago and about 37% year‑to‑date even after the pullback, but the message is clear: what rallies hardest can also fall fastest.

For Korea, the stakes go beyond a single bad day. A prolonged Iran conflict and sustained disruption around Hormuz would hit an export‑driven, fuel‑import‑dependent economy right where it hurts: energy costs, shipping, and global demand raising the risk that the Kospi’s AI‑powered boom turns into a much choppier ride.